Expand this Topic clickable element to expand a topic
OSA Publishing

Early Posting

Accepted papers to appear in an upcoming issue

OSA now posts prepublication articles as soon as they are accepted and cleared for production. See the FAQ for additional information.

Gas Refractometer Based on Side Open Fiber Optic Fabry-Perot Interferometer

Ruohui Wang, Pingchao Huang, Jiawei He, and Xue-Guang Qiao

Doc ID: 275180 Received 06 Sep 2016; Accepted 28 Nov 2016; Posted 28 Nov 2016  View: PDF

Abstract: In this paper, we present a gas refractometer based on an open cavity optical fiber Fabry-Perot interferometer. TheFabry-Perot cavity is fabricated by sandwiching a short section of preprocessed side hole fiber between two singlemode fibers. Chemical etching process creates a side open cavity through which gas can enter and leave freely. Bytracking the wavelength shift of the fringe pattern, the measurement of refractive index change of nitrogen can berealized. The experiment results show the gas RI sensitivity is up to 1290 nm/RIU.

Pixel Super-Resolution in digital holography by regularized reconstruction.

Corinne Fournier, Frederic Jolivet, Loïc Denis, Nicolas Verrier, Eric Thiebaut, Cédric ALLIER, and Thierry Fournel

Doc ID: 272280 Received 25 Jul 2016; Accepted 28 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: In-line digital holography (DH) and lensless microscopy are 3D imaging techniques used in many fields to reconstruct volume of micro-objects. Their performances are however limited by the pixel size of the sensor. Recently, various pixel super-resolution algorithms for digital holography have been proposed. An hologram with an improved resolution is produced from a stack of laterally shifted holograms, thus leading to a better resolved reconstruction compared to a single low-resolution hologram. Algorithms for super-resolved reconstructions based on inverse problems approaches have already shown an improvement in the 3D reconstruction of opaque spheres. Furthermore, maximum a posteriori (MAP) approaches have also shown their efficiency to reconstruct the object field more accurately and to extend the classical field-of-view. We propose an inverse problems formulation for DH pixel super-resolution. The method is detailed and applied to reconstruct synthetic and experimental holograms of sparse 2D objects. We show that our approach improves the shift estimation and the reconstruction quality. Moreover, the reconstructed field-of-view can be expanded up to a factor 3, thus making it possible to multiply by 9 the analyzed area.

Spectral bidirectional texture function (BTF) reconstruction by fusing RGB and spectral images

Hui-Liang Shen, Wei Dong, Xin Du, Si-Jie Shao, and John H. Xin

Doc ID: 273959 Received 16 Aug 2016; Accepted 27 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: Spectral bidirectional texture function (BTF) is essential for accurate reproduction of material appearance due to its nature of conveying both spatial and spectral information. A practical issue is that the acquisition of raw spectral BTFs is very time consuming. To resolve the limitation, this paper proposes a novel framework for efficient spectral BTF acquisition and reconstruction. The framework acquires multiple color (RGB) BTF images and just one spectral image. The full spectral BTFs are reconstructed by fusing the RGB and spectral images based on nonnegative matrix factorization (NMF). Experimental results indicate that the accuracy of spectral reflectance reconstruction is higher than existing algorithms. With the reconstructed spectral BTFs, the material appearance can be reproduced with high fidelity under various illumination conditions.

The Influence of coating thickness on laser-induced damage characteristics of anti-reflection coatings irradiated by 1064nm nanosecond laser pulses

Xinbin Cheng, Zhi Song, Hongping Ma, Jinlong Zhang, Bin Ma, Hongfei Jiao, and Zhanshan Wang

Doc ID: 274857 Received 30 Aug 2016; Accepted 27 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: The influence of coating thickness on laser-induced damage (LID) characteristics of anti-reflection (AR) coatings irradiated by 1064nm nanosecond laser pulses was investigated. Two HfO2/SiO2 AR coatings with different physical thickness, 0.7μm and 2.7μm, were prepared and tested. To study the effect of coating thickness on laser-induced damage threshold (LIDT) in isolation, electric field intensities (EFIs) at the substrate-coating interface were kept the same by using proper AR designs. Moreover, 2 nm artificial gold particles with a density of 10 mm-2 were implanted into the substrate-coating interface to achieve reliable experimental results. Optical microscope (OM) and scanning electron microscope (SEM) were used for online LIDT test and offline LID morphology observation respectively. The typical LID morphology of thicker AR coatings were flat bottom craters with diameter of 20~50 μm, which can be easily observed by online OM. For thinner AR coatings, hemispherical craters with diameter down to 1 μm were found as typical LID morphology by SEM. However, these tiny craters could not be observed by online OM. Moreover, such tiny craters did not grow with subsequent pulses, so they did not degrade the practical laser damage resistance of thin AR coatings. When identified with online OM, LIDT of thinner AR coatings is found about 2 times higher than the thicker ones, and large delamination was mainly found as the LID morphology of AR coatings with high fluence. When observed with SEM, LIDT of thin AR coatings with tiny craters was over 60% lower than the LIDT of thick AR coatings, which agrees with the model that fewer energy is required to form smaller LID craters of thinner coatings.

Simple ray-tracing model for a rough surface including multiple scattering effects

Yoshifumi Sekiguchi and Hiroki Kaneko

Doc ID: 276432 Received 27 Sep 2016; Accepted 25 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: For simulating lighting systems, we have developed a rough surface ray-tracing (RSRT) model on the basis of the facet model. The model needs to conserve energy to analyze how much light is lost in each component in the lighting system. Though a single-scattering rough surface model with a shadowing/masking function successfully describes the scattering distribution, masking output light violates the energy conservation law because it lacks multiple scattering. We thus developed an advanced RSRT (A-RSRT) model satisfying the energy conservation law and including a shadowing/masking effect as a consequence of multiple-scattering. To determine its accuracy, we set up a real shape (RS) model that outputs rigorous simulation results, although this RS model was impractical. The comparisons between the calculated results of the A-RSRT and RS models revealed that the A-RSRT model satisfied the energy conservation law and reproduced the scattering distribution precisely.

Active target based calibration of relative poses of mirrors in intra-oral scanners

Hongzhi Jiang, huijie zhao, Xiaoyue Liang, and Xudong Li

Doc ID: 277648 Received 27 Sep 2016; Accepted 25 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: This paper describes a practical method using active target to calibrate relative poses of mirrors in intra-oral scanners. Intra-oral scanning is a fast-growing technology. Mirrors are widely used in intra-oral scanners to increase the measuring area of a single view. The relative poses of these mirrors must be calibrated for accurate three-dimensional profiling. We present and analyze the geometric model of multi-view mirrors. A calibration method for relative poses of mirrors is developed based on fringe projection. Horizontal and vertical fringes are displayed on active target and every pixel can be viewed as a calibration marker. This calibration method allows the mirrors to have narrow common field of view. A cell phone display is chosen as active target, and experimental results demonstrate the effectiveness of the proposed method compared with traditional methods.

Detection of Huanglongbing in Florida using fluorescence imaging spectroscopy and machine learning methods

Caio Bruno Wetterich, Ruan Neves, José Belasque, Reza Ehsani, and Luis Marcassa

Doc ID: 270483 Received 13 Jul 2016; Accepted 25 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: In this study, we combine a fluorescence imaging technique and two machine learning methods to discriminate Huanglongbing (HLB) disease from zinc deficiency stress on samples from Florida, USA. Two classification methods, support vector machine (SVM) and artificial neural network (ANN) are used. Our classification results present high accuracy for both classification methods, 92.8% for SVM and 92.2% for ANN. The results from Florida are also compared to results from São Paulo state, Brazil. This comparison indicates that the present technique can be applied to discriminate HLB from zinc deficiency in both states.

Highly efficient omnidirectional structural color tuning method based on dielectric-metal-dielectric structure

Chenying Yang, Bo Fang, Weidong Shen, Xing Zhang, Yueguang Zhang, and Xu Liu

Doc ID: 272466 Received 28 Jul 2016; Accepted 25 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: A novel and convenient scheme is proposed to achieve the angle insensitive color filtering across a large color gamut by simply altering the thickness of the dielectric layer of Dielectric-Metal-Dielectric grating structure. The plasmonic filter presents a great feature of angle resolved spectrum response up to 60° and is independent of the azimuthal angle and the polarization state as well so as to construct an omnidirectional filter for its practical applications. The color tuning feature of the proposed filter with varied dielectric thickness is attributed to the modulation of condition for the localized surface plasmon resonance, which bears responsibility for omnidirectional property of this plasmonic filter. This color-tuning method with single mold size required can have wide applications in fields of display, colorful decoration, printing and so forth.

Phase-ratio imaging as applied to desert sands for tracking human presence

Alex Yuffa, Vadym Kaydash, Viktor Korokhin, Yuriy Shkuratov, Evgenij Zubko, and Gorden Videen

Doc ID: 272187 Received 22 Jul 2016; Accepted 25 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: Phase-ratio imaging exploits the fact that surfaces having different topographies have different phase curves. By taking the ratio of two images acquired at different illumination or observation conditions, regions having different topographies can be distinguished. We produce phase-ratio images from intensity images acquired at different observation times and locations in the desert environment of White Sands National Monument. Because of the lack of surface features, co-registration of the images is challenging, especially for images acquired from different observation locations. However, we do demonstrate that phase-ratio images can be used to identify disturbed sands. We also produce polarimetric and color-ratio images. These latter images do not suggest the possibility of identifying topographical differences due to human presence.

Determination of heavy metal Cr in pork by laser induced breakdown spectroscopy

Lin Huang, tianbing chen, Xiuwen He, hui yang, caihong wang, Muhua Liu, and Mingyin Yao

Doc ID: 270640 Received 19 Jul 2016; Accepted 24 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: Meat can be polluted by heavy metals during feeding of livestock and logistics .It is necessary to monitor theconcentration of toxic metals in meat .The element Cr (chromium) in pork was selected as determination target inthis work. Fresh pork was polluted in Cr solution to make different content level. And the polluted ones were driedand pressed to pellets to eliminate the effect of water and improve the stability and sensitivity of LIBS. The spectra ofpressed pellets were collected at optimized LIBS experimental parameters. After that, the real content of sampleswas obtained by AAS. Characteristic lines Cr I 425.43,Cr I 427.48 and Cr I 428.97 were verified and the modelbetween LIBS intensity of line peak and actual concentration of Cr was constructed. The results displayed that themodel has better predicted precision and accuracy, especially applying line Cr I 425.43 for calibration. This work isobvious that LIBS has the potential in detecting the heavy metals residue in meat and food safety.

Further investigations of modal wavefront reconstruction based on Zernike polynomials for lateral shearing interferometry

Fengzhao Dai, Yazhong Zheng, Yang Bu, and Xiangzhao Wang

Doc ID: 278796 Received 14 Oct 2016; Accepted 24 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: The Zernike-polynomials-based modal reconstruction method is an important wavefront reconstruction method for lateral shearing interferometry. There are four typical Zernike-polynomial-based modal reconstruction methods: the Rimmer-Wyant method (R-W), the elliptical orthogonal transformation method (EOT), the numerical orthogonal transformation method (NOT), and the difference Zernike polynomial fitting method (DZF). In a previous paper [Appl. Opt. 51, 5028 (2012)], the overall performances of these four methods were comprehensively compared with each other. The conclusions showed that NOT and DZF have the highest reconstruction accuracies among these four methods. In addition, it was shown that the performance of NOT is identical to that of DZF; however, the reason behind this was not known, until now. In the present paper, we present a strictly mathematical proof for this highly significant result.

Closure and uncertainty assessment for ocean color reflectance using measured volume scattering functions and reflective tube absorption coefficients with novel correction for scattering

Alberto Tonizzo, Michael Twardowski, Scott McLean, Kenneth Voss, Marlon Lewis, and Charles Trees

Doc ID: 274965 Received 06 Sep 2016; Accepted 23 Nov 2016; Posted 30 Nov 2016  View: PDF

Abstract: Optical closure is assessed between measured and simulated Rrs using Hydrolight radiative transfer code for five datasets that included a broad range of both Case I and Case II water types. Model-input IOPs were the absorption coefficient determined with a WET Labs ac9 and the volume scattering function (VSF) determined with a custom in situ device called MASCOT. Optimal match ups were observed using measured phase functions and reflective tube absorption measurements corrected using a scattering error independently derived from VSF measurements. Absolute bias for simulations compared to measured Rrs was 20% for the entire data set, and 17% if a relatively shallow station with optical patchiness is removed from the analysis. The latter is about twice the bias observed in direct radiometric comparisons from a previous study (Voss et al. 2010). For exercises where such bias can be tolerated, IOPs have the potential to aid in ocean color validation. Overall bias was roughly consistent with the sum of bias uncertainties derived from associated measurements, although larger deviations were observed in several cases. Applying Fournier-Forand phase functions derived from particulate backscattering ratios according to Mobley et al. (2002) resulted in overall bias that was almost as good ( %) as results from simulations using measured phase functions when using the independently derived scattering correction for absorption. Possibilities for improving closure assessments in future studies, including addressing full polarization in modeling radiative transfer, are discussed.

Numerical Analysis of Computational Cannula Microscopy

Rajesh Menon and Ganghun Kim

Doc ID: 275238 Received 07 Sep 2016; Accepted 23 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: Microscopy in hard-to-reach parts of a sample such as the deep brain can be enabled by computational cannula microscopy (CCM), where light is transported from one end to the other end of a solid-glass cannula. Computational methods are applied to unscramble the recorded signal to obtain the object details. Since the cannula itself can be microscopic (~250μm in diameter), CCM can enable minimally invasive imaging. Here, we describe a full-scale simulation model for CCM and apply it to not only explore the limits of the technology, but also use it to improve the imaging performance. Specifically, we show that the complexity of the inverse problem to recover CCM images increases with the aspect ratio (length/diameter) of the cannula geometry. We also perform noise tolerance simulations, which indicate that the smaller aspect ratio cannula tolerate noise better than the longer ones. Analysis on noise tolerance using the proposed simulation model showed 2-3x improvement in noise tolerance when the aspect ratio is reduced in half. We can utilize these simulation tools to further improve the performance of CCM and extend the reach of computational microscopy.

Local polynomial approximation based phase unwrapping using state space analysis

Pramod Rastogi and Rishikesh Kulkarni

Doc ID: 275836 Received 13 Sep 2016; Accepted 23 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: A new method of phase unwrapping is proposed for the absolute phase estimation based on the first order polynomial phase approximation within a symmetric window generated around each pixel. The accurate estimation of polynomial coefficients is performed by formulating them as the elements of a state vector in a state space model. The extended Kalman filter offers a robust approach for the state estimation with the capability of handling high noise power. The polynomial coefficients estimates obtained at a given pixel are used as the initial conditions of the Kalman filter for its neighboring pixel which results in the unwrapped phase estimation. The simulation and experimental results validate the performance of the proposed phase unwrapping method along with its ability of handling the masked phase fringe patterns with the help of a pre-defined binary mask and a pixel selection strategy.

Determination of the optical constants of a dielectric layer by processing in situ spectral transmittance measurements along the time dimension

Michel Lequime, Severin NADJI, Dragan Stojcevski, Cihan Koc, Catherine GREZES-BESSET, and Julien Lumeau

Doc ID: 275839 Received 13 Sep 2016; Accepted 23 Nov 2016; Posted 29 Nov 2016  View: PDF

Abstract: This paper describes a new method based on the use of a broadband monitoring system to determine the spectral dependence of the optical constants of a layer without using a dispersion model.

Stability transfer at 1.5 µm for metrological applications using a commercial optical cavity

frédéric Du Burck, AMINE CHAOUCHE RAMDANE, PIERRE GRUNING, and Vincent Roncin

Doc ID: 274713 Received 29 Aug 2016; Accepted 23 Nov 2016; Posted 23 Nov 2016  View: PDF

Abstract: A compact device for optical frequency stability transfer based on a cavity referenced to a molecular transition at 1.5 µm is described. The setup is essentially fibred and uses commercial components: a tunable confocal cavity, extended cavity laser diodes, a DFB laser and a H13C14N cell. Phenomena which limit the stability are carefully studied. It is shown that the short-term stability is limited by the spectral purity of sources and the long-term stability by the residual amplitude modulation inherent to our current setup. The stability transfer of the molecular reference over 7 nm is demonstrated at a level of 10-10 in relative value, limited by the detected molecular linewidth. Improvements to the device are studied and it is shown that a stability transfer at 10-12 level could be achieved.

SLM based adaptive optical system for the use of multiple phase retrieval methods

Christian Lingel, Tobias Haist, and Wolfgang Osten

Doc ID: 278265 Received 06 Oct 2016; Accepted 23 Nov 2016; Posted 23 Nov 2016  View: PDF

Abstract: We propose an adaptive optical setup using a spatial light modulator (SLM), which is suitable to perform different phase retrieval methods with varying optical features and without mechanical movement. By this approach, it is possible to test many different phase retrieval methods and their parameters (optical and algorithmic) using one stable setup and without hardware adaption. We show exemplary results for the well known transport of intensity equation (TIE) method and a new iterative adaptive phase retrieval method, where the object phase is canceled by an inverse phase written into part of the SLM. The measurement results are compared with white light interferometric measurements.

Multifocus Image Fusion Using Superpixel Segmentation and Superpixel-based Mean Filtering

Long Chen, philip Chen, and Junwei Duan

Doc ID: 277591 Received 27 Sep 2016; Accepted 22 Nov 2016; Posted 22 Nov 2016  View: PDF

Abstract: To achieve better performance in multifocus image fusion problems, a new regional approach based on superpixels and superpixel-based mean filtering is proposed in this paper. First, a fast and effective seg- mentation method is adopted to generate the superpixels over clarity-enhanced average images. Due to the application of clarity enhanced images, we derive segments that are more consistent with the clarity information in source images. The superpixel partition’s flexibility in selecting segment number also pro- vides us the chance to get more homogeneous segmentation. By averaging the clarity information in each superpixel, we make the decision map of fusion by regionally selecting sharper superpixels in different source images. Finally, a novel superpixel-based mean filtering technique is introduced to make full use of spatial consistency in images and the filtered final decision map is produced. The final fused image is constructed by pixels from different source images according to the final decision map. Experimen- tal results demonstrate that the proposed method can obtain state-of-the-art performance for multi-focus image fusion problem.

Variations of spherical aberration and central coma of conceptual thin lenses

Chaohsien Chen

Doc ID: 278807 Received 14 Oct 2016; Accepted 21 Nov 2016; Posted 22 Nov 2016  View: PDF

Abstract: Based on our earlier matrix algorithms (Chen, J. Mod. Opt., 55, 105, 2008) for evaluating the variations of Seidel aberrations, new concise equations are derived to directly evaluate the variations of spherical aberration and central coma of conceptual thin lenses when the incident marginal and chief rays are arbitrarily changed. In the earlier algorithms, four cases with distinct translation factors and matrix equations are required according to the relationships of the object and pupil positions, otherwise, division-by-zero errors or insufficient numerical accuracy will be encountered. Conversely, the new versatile equations are always accurate for all kinds of object and pupil positions, one example verifying this property is illustrated. Another example is given to explain why a symmetrical thin lens can provide only one, rather than two, degree of freedom for correcting Seidel aberrations.

Investigation Of Phase Object Trace Duplication In Moiré Deflectometry

Khosro Madanipour and Mohammad Ahmadi

Doc ID: 278582 Received 17 Oct 2016; Accepted 21 Nov 2016; Posted 23 Nov 2016  View: PDF

Abstract: In deflectometry experiment for finding the temperature distribution around a hot wire as a phase object, the trace of the wire in moiré pattern is duplicated and it is observed that, the separation of the wire traces varies when the distance between two gratings of moiré deflectometry setup is changed. By investigation of moiré deflectometry, it is found, the object trace duplication cannot be interpreted by ray deflection theory which is based on geometric optics, so by using diffraction theory, the effect of a phase object on moiré pattern is studied and some generalized formulations are presented. It is demonstrated that, the deformation of moiré fringes does not originate from the wave front derivative, but superposition of two separated wave fronts causes fringes deformation, by this approach the accuracy of ray deflection analysis is improved. Finally the results of this model are simulated, it has a good agreement with the experimented one.

Optical, Structural and Mechanical Properties of Silicon Oxynitride Films Prepared by Pulsed Magnetron Sputtering

Chien-Jen Tang, Cheng-Chung Jaing, Cheun-Lin Tien, Wei-Chiang Sun, and Shih-Chin Lin

Doc ID: 270753 Received 29 Jul 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: Silicon oxynitride films were deposited by reactive pulsed magnetron sputtering. The optical, structural and mechanical properties of silicon oxynitride films with different nitrogen proportions were analyzed via spectroscopy, atomic force microscopy, Twyman-Green interferometer and nanoindentation. The refractive indices of the silicon oxynitride films were adjusted from 1.487 to 1.956 with the increase in nitrogen proportions. The surface roughness decreased from 1.33 to 0.97 nm with the increase in nitrogen proportions. The residual stress of the silicon oxynitride films was higher than for pure silicon nitride and silica films. The hardness and Young’s modulus increased from 13.51 to 19.74 GPa and 110.41 to 140.49 GPa with the increase in nitrogen proportions, respectively. The hardness and Young’s modulus of antireflection coatings using silicon oxynitride film were 13.64 GPa and 102.11 GPa, respectively. Silicon oxynitride film could be used to improve the hardness of antireflection coatings.

Single photon counting polarization ghost imaging

Jianhong Shi, Guihua Zeng, and Yuxin Liu

Doc ID: 274572 Received 26 Aug 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: We proposed a method for polarization ghost imaging based on single photon counting. With time-correlated single-photon-counting technique, we can construct photons time distribution histograms and select a distance gate to accurately estimate the light intensity. Experiment are performed to realize the scheme of discriminating the object from the different material background in weak illumination. In the situation that ambient noise is significantly stronger than the signal, our method still can retrieve image as ambient noise is mostly filtered out through distance gate selection. We suppose that our method may facilitate applications in remote target discrimination and biological imaging.

The Theory and Experiment of Phasing Detection by use of Two Wavelengths

Li Bin, Wenhao yu, Hao Xian, and Jinlong tang

Doc ID: 275502 Received 07 Sep 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: Wavefront sensing in monochromatic light has ambiguity.To resolve this ambiguity, the wavefront sensing is performed in two wavelengths. And a new algorithm is proposed to find the correct phase, also the algorithm is verified by simulation. Using the algorithm, the capture range of a wavefront sensor can be extended from on the order of in segmented mirror piston to several waves. Lastly, a co-phasing experiment system of segmented mirror is built to verity the algorithm.In the experiment, one wavelength is 0.65um, the others is 0.636um.After the co-phasing fine-tuning of the segmented mirror,the piston error of segmented mirror is better than λ/20.

One-dimensional searches for finding new lens design solutions efficiently

Zhe Hou, Florian Bociort, and Irina Livshits

Doc ID: 275790 Received 13 Sep 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: A special structure is present in the lens design landscape that makes it different from a general global optimization problem: many local minima are closely related to minima of simpler problems and can therefore be found by decomposing the search for them in simple steps. We show here that in the design landscape of a wide-angle pinhole lens and in closely related optimization landscapes, all good local minima found by other methods can be obtained easily with a succession of one-dimensional searches starting from simpler systems. By replacing high-dimensional searches with a succession of one-dimensional searches the design efficiency can be increased significantly. By combining this method with conventional design methods the wide angle pinhole lens can be designed starting from a single lens.

General Optical Discrete Z Transform: Design and Application

Nam Ngo

Doc ID: 276273 Received 21 Sep 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: This paper presents a generalization of the discrete z transform (GOD-ZT) algorithm. It is shown that the GOD-ZT algorithm is a generalization of several important conventional discrete transforms. Based on the GOD-ZT algorithm, a tunable general optical discrete z transform (GOD-ZT) processor is synthesized using the silica-based finite impulse response (FIR) transversal filter. To demonstrate the effectiveness of the method, the design and simulation of a tunable optical discrete Fourier transform (ODFT) processor as a special case of the synthesized GOD-ZT processor is presented. It is also shown that the ODFT processor can function as a real-time optical spectrum analyzer. The tunable ODFT has an important potential application as a tunable optical demultiplexer at the receiver end of an optical orthogonal frequency-division multiplexing (OFDM) transmission system.

Generation of twisted light waves by use of vector beam recorded functionalized liquid crystals

Moritsugu Sakamoto, Tomoyuki Sasaki, Tran Tien, Kohei Noda, Nobuhiro Kawatsuki, and Hiroshi Ono

Doc ID: 276341 Received 22 Sep 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: Twisted light beams, or optical vortices (OVs), have unique properties, including dark holes and orbital angular momentum of light, and hence many OV generation approaches have been proposed. In this study, we demonstrate a polarization-addressed OV generator consisting of functionalized polymer liquid crystal composites. Uniaxially aligned azo dye-doped liquid crystals can form three-dimensional twisted anisotropic structures under vector beam illumination, which has a space-variant polarization distribution. Photo-induced anisotropic structures have spatial light modulation properties that can convert polarized Gaussian beams into OVs. These properties can be controlled by varying the illuminating vector-polarized fields and their intensity distributions. Simulations showed that the generator has achromatic wavefront modulation properties for broadband spectra. The induced anisotropic structure can be re-initialized by turning it off and changing the vector beam polarization distribution. The OV generator thus has optical switching properties that enable generation of various OV topologies.

High Definition Optical Coherence Tomography Imaging for Non-Invasive Examination of Heritage Works

farzana zaki, ISABELLA HOU, DENVER COOPER, DIVYA PATEL, Yi Yang, and Xuan Liu

Doc ID: 277568 Received 26 Sep 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: Cultural heritage works such as ancient murals and historical paintings, are examined routinely for the purpose of conservation. Previous works have applied OCT, which is a three-dimensional (3D), microscopic imaging modality, in the field of heritage works conservation. The data acquired by OCT provides both 3D surface information of the object and structure information underneath the surface. Therefore, cross-sectional information of the object can be utilized to study layer structure of the painting and brush stork techniques used by the artist. However, as demonstrated in previous studies, OCT has limited capability in high definition (HD) examination of paintings or murals which are in macroscopic scale. HD examination of heritage works needs to scan large areas and process huge amount of data, while OCT imaging has limited field of view and processing power. To further advance the application of OCT in the conservation of heritage works, we demonstrate a novel high-speed, large field-of-view (FOV) OCT imaging platform. Our results suggest that this OCT platform has the potential to become a nondestructive alternative for the analysis and conservation of paintings and murals.

Optimization of lightweight structure and supportingbipod flexure for a space mirror

Yi-Cheng Chen, BO-KAI HUANG, ZHEN-TING YOU, CHIA-YEN CHAN, and Ting-Ming Huang

Doc ID: 277744 Received 27 Sep 2016; Accepted 21 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: This article presents an optimization process for integrated optomechanical design. The proposed optimizationprocess for integrated optomechanical design comprises computer aided drafting, finite element analysis (FEA),optomechanical transfer codes, and an optimization solver. The FEA was conducted to determine mirror surfacedeformation; then, deformed surface nodal data were transferred into Zernike polynomials through Matlaboptomechanical transfer codes to calculate the resulting optical path difference (OPD) and optical aberrations. Toachieve an optimum design, the optimization iterations of the FEA, optomechanical transfer codes, andoptimization solver were automatically connected through a self-developed Tcl script. Two examples ofoptimization design were illustrated in this research, namely an optimum lightweight design of a Zerodur primarymirror with an outer diameter of 566 mm that is used in a space-borne telescope and an optimum bipod flexuredesign that supports the optimum lightweight primary mirror. Finally, optimum designs were successfullyaccomplished in both examples, achieving a minimum peak-to-valley (PV) value for the OPD of the deformedoptical surface. The simulated optimization results showed that (1) the lightweight ratio of the primary mirrorincreased from 56% to 66%; and (2) the PV value of the mirror supported by optimum bipod flexures in the horizontalposition effectively decreased from 228 nm to 61 nm.

Automatic full compensation of quantitative phase imaging in off-axis digital holographic microscopy

Carlos Trujillo, Jorge Garcia-Sucerquia, Juan Piedrahita-quintero, and Raul Castañeda

Doc ID: 278850 Received 17 Oct 2016; Accepted 20 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: An automatic method that fully compensates the quantitative phase measurements in off-axis digital holographic microscopy (DHM) is presented. The two main perturbations of the quantitative phase measurements in off-axis DHM are automatically removed. While the curvature phase flaw introduced by the microscope objective is avoided by the use of an optimized telecentric imaging system for the recording of the holograms, the remaining phase perturbation due to the tilt of the reference wave is removed by the automatic computation of a digital compensating reference wave. The method has been tested on both non- and -biological samples with and improving on the quality of the recovered phase maps.

Wavelength tunable ultrafast fiber laser via reflective mirror with taper structure

Li FANG, chuyun huang, Ting Liu, Noelle Gogneau, Eric Bourhis, Jacques Gierak, and Jean-Louis Oudar

Doc ID: 275699 Received 19 Sep 2016; Accepted 20 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: Lasers source with controllable flexible wavelength have find widespread applications in the fields of optical fiber communication, optical sensing, and microscopy. Here, we report a tunable mode-locked fiber laser using graphene based saturable absorber and a tapered mirror as end mirror in the cavity. The phase layer in the mirror is precisely etched by focused ion beam (FIB) milling technology, and the resonant wavelength of the mirror shifts corresponding to the different etch depths. By scanning the tapered mirror mechanically, the center wavelength of mode-locked fiber laser can be continuously tuned from 1562nm to 1532nm, with pulse width in sub-ps level and repetition rate of 27 MHz.

Energy feedback freeform lenses for uniform illumination of extended light source LEDs

Xinrui Ding, Zongtao li, Shudong Yu, Liwei Lin, Yong Tang, Wei Yuan, and Binhai Yu

Doc ID: 274786 Received 30 Aug 2016; Accepted 20 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: Using freeform lenses to construct uniform illumination systems is important in light-emitting diode (LED) devices. In this paper, the energy feedback design is used for freeform lens (EFFL) constructions by solving a set of partial differential equations that describe the mapping relationships between the source and the illumination pattern. The simulation results show that the method can overcome the illumination deviation caused by the extended light source (ELS) problem. Furthermore, a uniformity of 95.6% is obtained for chip-on-board (COB) compact LED devices. As such, prototype LEDs manufactured with the proposed freeform lenses demonstrate significant improvements in luminous efficiency and emission uniformity.

Lossless and lossy compression of quantitative phase images of red blood cells obtained by digital holographic imaging

Inkyu Moon, KEYVAN JAFERJADEH, and SAMANEH GHOLAMI

Doc ID: 273623 Received 11 Aug 2016; Accepted 20 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: In this paper, we evaluate lossless and lossy compression techniques to compress quantitative phase images of redblood cells (RBCs) obtained by off-axis digital holographic microscopy (DHM). The RBC phase images arenumerically reconstructed from their digital holograms and are stored in 16-bit unsigned integer format. In thecase of lossless compression, predictive coding of JPEG lossless (JPEG-LS), JPEG2000 and JP3D are evaluated, andcompression ratio (CR) and complexity (compression time) are compared against each other. It turns out thatJPEG2000 can outperform other methods by having the best CR. In the lossy case, JPEG2000 and JP3D with differentCRs are examined. Because some data is lost in a lossy way, the degradation level is measured by comparingdifferent morphological and biochemical parameters of RBC before and after compression. Morphologicalparameters are volume, surface area, RBC diameter, sphericity index, and the biochemical cell parameter is meancorpuscular hemoglobin (MCH). Experimental results show that JPEG2000 outperforms JP3D not only in term ofmean square error (MSE) when CR increases, but also in compression time in the lossy compression way. Inaddition, our compression results with both algorithms demonstrate that with high CR values the 3D profile of RBCcan be preserved and morphological and biochemical parameters can be still within the range of reported values.

Dispersion relations of refractive indices suitable for KBBF crystal deep UV applications

Rukang Li, Lirong Wang, Xiao Wang, Guiling Wang, and Chuangtian Chen

Doc ID: 276272 Received 21 Sep 2016; Accepted 20 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: KBe2BO3F2 (KBBF) is the only nonlinear optical crystal available to generate deep ultraviolet (DUV) laser output by direct harmonic generations. High precision refractive indices including the DUV region were measured and starting from a double resonance model of polarizability, new dispersion relations of the refractive indices were deduced from the measured data. The predicted phase matching angles for second harmonic generation down to 170nm from the new relations agree well to the previous reported values. Moreover, the new dispersion relations show superior results in even shorter wavelength range giving perfect calculated phase matching angles for the fifth harmonic generation down to as short as 149.8nm.

Coplanar waveguide wideband band-stop filter based on localized spoof surface plasmons

Zhuo Li, Jia Xu, Chen Chen, Yunhe Sun, Bingzheng Xu, Liangliang Liu, and Changqing Gu

Doc ID: 278579 Received 14 Oct 2016; Accepted 20 Nov 2016; Posted 23 Nov 2016  View: PDF

Abstract: In this work, a wideband band-stop plasmonic filter based on localized spoof surface plasmons (LSSPs) is reported, which consists of a coplanar waveguide(CPW) and an ultra-thin periodic corrugated metallic strip with defect units at the back of the substrate. Defect units are used to localize the transmission energy along the CPW. Each defect unit can introduce a narrow stop band and a series of defect units are judiciously designed to form a broadband CPW band-stop filter. The center frequency and bandwidth of the filter can be tuned by the heights and numbers of the defect units. In addition, a T-shaped unit is designed to increase the equivalent height of the lateral branch so as to realize the miniaturization of the vertical geometric dimension. Theoretical analysis of the filter has been conducted and a sample at microwave frequency has been fabricated and measured to validate our design. This simple band-stop plasmonic filter can find potential applications in plasmonic circuits and antennas at microwave and THz frequencies.

Hybrid Plasmonic Waveguide with Centimeter Scale Propagation Length for Nanoscale Optical Confinement

Sandeep Dahiya, Suresh Kumar, and Brajesh Kaushik

Doc ID: 274256 Received 22 Aug 2016; Accepted 19 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: The centimeter scale Hybrid Plasmonic Waveguide (HPW) structure based on grating is proposed at telecom wavelengths. High contrast grating is formed by Si and Air placed in the air slot created in the high index region for attaining the nano-scale optical confinement. High contrast grating helps in enhancement of the propagation length up to 3.6 cm with very low loss 0.11dB/mm. Further, the extremely large figure of merit (FoM) 11296 (> 10^7) with nanoscale confinement 0.00081/μm2 is introduced. In present work, Finite Element Method (FEM) based COMSOL Multiphysics software have applied to simulate and analyze the properties of HPW structure. The proposed HPW device can be used for the applications of next generation of nanolaser and modulators.

Photoelastic properties of lithium tetraborate crystals

Rostyslav Vlokh, Oleh Krupych, Oksana Mys, Taras Kryvyy, Volodymyr Adamiv, and Yaroslav Burak

Doc ID: 276212 Received 20 Sep 2016; Accepted 19 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: We report the results of comprehensive studies of the piezooptic and elastooptic effects in lithium tetraborate crystals, Li2B4O7. The full matrices of piezooptic and elastooptic coefficients are obtained using a recently devel-oped method based on four-point bending. On this basis, we have estimated the acoustooptic figure of merit for Li2B4O7.

Graphene Based Side-polished Optical Fiber Amplifier

Mohammad Karimi, Vahid Ahmadi, and Masoud Ghezelsefloo

Doc ID: 273631 Received 24 Aug 2016; Accepted 18 Nov 2016; Posted 21 Nov 2016  View: PDF

Abstract: We demonstrate a novel design for optical fiber amplifiers, utilizing side-polished fibers with single layer graphene overlay as active medium and carrier injection in the graphene layer to provide required inversion. We study effects of an electrically induced graphene p-i-n hertojunction in forward bias regime on optical modes of side-polished fibers and show gain values of 0.51 dB/cm, 1.81 dB/cm and 1.79 dB/cm for wavelengths 1064 nm, 1330 nm and 1550 nm can be obtained for single mode side polished fibers. Our results show that in multi-mode side polished fibers, higher order modes experience higher values of gain and gain can be increased by increasing polished depth. The proposed system is a tunable wideband optical amplifier which can operate for wavelengths larger than 1000 nm.

An effective star tracking method based on optical flow analysis for star trackers

Ting Sun, Fei Xing, Xiaochu Wang, li jin, Minsong Wei, and Zheng You

Doc ID: 273400 Received 09 Aug 2016; Accepted 18 Nov 2016; Posted 18 Nov 2016  View: PDF

Abstract: Benefiting from rapid development of imaging sensor technology, modern optical technology, and high-speed computing chip, the accuracy, dynamic performance and update rate of the star tracker have been greatly improved with low power consumption and miniature size. It is currently one of the most competitive attitude measurement sensors. However, due to restrictions of optical imaging system, difficulties still exist in moving star spot detection and fast star tracking when in special motion conditions. An effective star tracking method based on optical flow analysis for star trackers is proposed in this manuscript. Spot-based optical flow, based on gray gradient between two adjacent star images, is analyzed to distinguish the star spot region and obtain accurate star spot position so that the star tracking can keep continuous under high dynamic conditions. The obtained star vectors and extended Kalman filter (EKF) are then combined to conduct angular velocity estimation to ensure region prediction of the star spot, which can be combined with the optical flow analysis result. Experiment results show that the method proposed in this manuscript has advantages in conditions of large angular velocity and large angular acceleration, despite the presence of noise. Higher functional density and better performance can be achieved, thus the star tracker can be more widely applied in small satellites, remote sensing and other complex space missions.

Biaxial stress and optoelectronic properties of AZOthin films deposited on flexible substrates by radiofrequency magnetron sputtering

Hsi-Chao Chen, Po-Wei Cheng, and Kuo-Ting Huang

Doc ID: 274647 Received 29 Aug 2016; Accepted 18 Nov 2016; Posted 18 Nov 2016  View: PDF

Abstract: Transparent conductive Al-doped ZnO (AZO) thin films were deposited on polyethylene terephthalate (PET) andpolycarbonate (PC) substrates using radio frequency (RF) magnetron sputtering. The biaxial stress was measuredwith a double beam shadow moiré interferometer, and an X-ray diffraction (XRD) was used to investigate thecrystal orientation of ZnO. The substrate temperature was varied from room temperature to 150°C in steps of 25°C.The experimental results showed that the residual and shearing stresses increased with the increase in substratetemperature. The residual stress can be separated into principle and shearing stresses by Mohr’s circle rule, andthe shearing stress, tensile stress, was different from the compressive stress of the residual stress. However, theoptimal substrate temperatures for PET and PC were 75°C and 100°C, and the shearing stresses were 424.82 MPaand 543.68 MPa, respectively. The AZO/PET and AZO/PC thin films cracked at substrate temperatures of 75°C and100°C, respectively. AZO/PET thin film at a substrate temperature of 100°C had a resistivity low to the order of 10-3Ω-cm.

Bilateral fitting subtracting confocal microscopy

Weiqian Zhao, Zhong Sheng, Lirong Qiu, Yun Wang, and Rongjun Shao

Doc ID: 275591 Received 09 Sep 2016; Accepted 18 Nov 2016; Posted 18 Nov 2016  View: PDF

Abstract: This paper proposes a bilateral fitting subtracting confocal microscopy (BFSCM) bases on the optical arrangement of conventional confocal microscopy (CM). BFSCM first uses the data in both sides of confocal axial response curve, which are very sensitive to the axial position of the sample, for respective linear fitting to obtain two fitting straight lines, and then obtains a difference confocal line by subtraction of the two fitting lines. Finally, it calculates the zero position of the difference confocal line to precisely capture the focus position of confocal system, and thereby achieving a high precision measurement of 3D structure of the sample. The theoretical analyses and experiments indicate that BFSCM can improve the axial resolution, and have the anti-interference capability and focusing ability with bipolar absolute zero point tracking, while it does not change the structure and lateral resolution of CM. BFSCM provides a novel method for the improvement of CM axial resolution.

Tomographic Optical Emission Spectroscopy of a High Enthalpy Air Plasma Flow

Tobias Hermann, Stefan Löhle, Stefanos Fasoulas, and Andreas Andrianatos

Doc ID: 275642 Received 13 Sep 2016; Accepted 17 Nov 2016; Posted 18 Nov 2016  View: PDF

Abstract: A method is presented allowing for locally resolved emission spectroscopy using a tomographic setup. The approach is presented in this work applied to a high enthalpy air plasma flow. The resulting data sets allow for a three-dimensional representation of the non-symmetric flowfield using photographs of the test section and two-dimensional representation of the spectrally resolved radiance of the flow field. An analysis of different exposure times shows that transient fluctuations of the plasma can result in substantial asymmetry which approaches symmetry only for longer exposure times when the temporal averaging of the emission is significant. The spectral data allows the analysis of species selective exciation and emission. A non-equilibrium between atomic and molecular excitation temperatures is concluded for the investigated air plasma flow field. The spatial distribution of atomic electronic excitation temperatures are close to rotational symmetry while molecular rotational and vibrational temperatures exhibit an asymmetric behavior.

Characterization of coherence-or-power selectable operation of an external-cavity semiconductor diode laser

Masaharu Hyodo, Masayoshi Watanabe, Akira Kawakami, Shingo Saito, and Masaaki Adachi

Doc ID: 276392 Received 22 Sep 2016; Accepted 17 Nov 2016; Posted 18 Nov 2016  View: PDF

Abstract: The properties of the coherence-or-power selectable operation of an external-cavity semiconductor diode laser through the control of intracavity polarization states have been characterized in detail. In our technique, a diffraction grating and a reflector functioned as a polarization-dependent output coupler, such that the portion of light fed back to the gain medium was readily controlled by rotating the intracavity polarization axis, which resulted in the selectable operation of either high degree of coherence or high power for the laser output. We could continuously sweep the correlation widths over a range of approximately one order of magnitude, as well as four-folded output powers by simply rotating the intracavity half-wave plate. We also demonstrated experiments on optical phase locking using two independent coherence-or-power selectable lasers.

Hybrid integrated optical waveguides in glass forenhanced visible photoluminescence of nano-emitters

Josslyn Beltran Madrigal, Ricardo Tellez Limon, Florent Gardillou, Denis Barbier, Wei Geng, Christophe Couteau, Rafael Salas-Montiel, and Sylvain Blaize

Doc ID: 274916 Received 13 Sep 2016; Accepted 17 Nov 2016; Posted 18 Nov 2016  View: PDF

Abstract: Integrated optical devices able to control light-matter interaction at the nanoscale had attracted theattention of the scientific community in recent years. However, most of these devices are based onsilicon waveguides, limiting their use for telecommunication wavelengths. In this contribution, wepropose an integrated device that operates with light in the visible spectrum. The proposed deviceis a hybrid structure consisting of a high refractive index layer placed on top of an ion-exchangedglass waveguide. We demonstrate that this hybrid structure serves as an efficient light coupler for theexcitation of nanoemitters. The numerical and experimental results show that the device can enhancethe electromagnetic field confinement up to 11 times, allowing a higher photoluminescence signal fromnanocrystals placed on its surface. The designed device opens new perspectives in the generation of newoptical devices suitable for quantum information or for optical sensing.

Development and characterization of high suppressionand high etendue narrowband spectral filters

Adam Kinos, Qian Li, Lars Rippe, and Stefan Kröll

Doc ID: 278344 Received 11 Oct 2016; Accepted 16 Nov 2016; Posted 18 Nov 2016  View: PDF

Abstract: The present work addresses some critical issues in constructing high suppression, narrowband spectral filters in rare-earth-ion-doped crystals, mainly targeting the application of ultrasound optical tomography, but also applicable for areas such as quantum memories, self-filtering of laser frequencies, and other applications relying on high absorption in rare-earth-ion-doped crystals. The polarization of light transmitted through a highly absorbing crystal is experimentally analyzed. Additionally, an existing wave propagation method is used to simulate beam propagation through a spectral hole to study the high etendue requirements of ultrasound optical tomography.

Non-contact detection of delaminational defects in glass fiber reinforced polymer composites using terahertz imaging

Hong-Liang Cui, JIN ZHANG, JINBO ZHANG, YAN SHEN, Xiaohui Han, JIE WANG, and Changcheng Shi

Doc ID: 274790 Received 30 Aug 2016; Accepted 16 Nov 2016; Posted 16 Nov 2016  View: PDF

Abstract: We employed terahertz (THz) time domain spectroscopy (TDS) imaging technology, a new nondestructive testing(NDT) method, to detect the inclusions of glass fiber reinforced polymer (GFRP) composites. The refractive indexand absorption coefficient of two types of GFRP composites (epoxy GFRP composites and polyester GFRPcomposites) were first extracted, and GFRP composites with Teflon inclusions were examined, including an epoxyGFRP solid panel with a smaller Teflon inclusion hidden behind a larger Teflon inclusion, and polyester GFRP solidpanels with Teflon inclusions of various sizes, at different depths. It was experimentally demonstrated that THzTDS imaging technology could clearly detect a smaller inclusion hidden behind a larger inclusion. When thereflected THz pulse from the inclusion did not overlap with that from the front surface of the sample, removal ofthe latter before Fourier transform was shown to be helpful in imaging the inclusions. With sufficiently strongincident THz radiation, inclusion insertion depth had little impact on the ability of THz wave to detect inclusions.However, as the thickness of the inclusion became thinner, the inclusion detection ability of THz wavedeteriorated. In addition, with a combination of reflected C-scan imaging and B-scan imaging using the reflectedtime domain waveform, both the lateral sizes and locations of the inclusions, and the depths and thicknesses of theinclusions were clearly ascertained.

Laguerre-Gauss and Bessel-Gauss Beams Propagation Through Turbulence: Analysis of Channel Efficiency

Timothy Doster and Abbie Watnik

Doc ID: 274426 Received 02 Sep 2016; Accepted 16 Nov 2016; Posted 17 Nov 2016  View: PDF

Abstract: As a means of increasing the channel capacity in free-space optical communication systems, two OAM carrying beams, Bessel-Gauss and Laguerre-Gauss, are studied. In a series of numerical experiments, we show that Bessel-Gauss beams, a pseudo non-diffracting beam, outperform Laguerre-Gauss beams of various orders in channel efficiency and bit-error-rates.

Forward scattering of polarized light from a turbid slab: Theory and Monte Carlo simulations

Soichi Otsuki

Doc ID: 277828 Received 29 Sep 2016; Accepted 16 Nov 2016; Posted 17 Nov 2016  View: PDF

Abstract: It is proved that if reciprocity and mirror symmetry hold for single scattering by a particle, they also hold for multiple scattering in turbid slab media. Monte Carlo simulations generate a reduced effective Mueller matrix for the forward scattering, which satisfies reciprocity and mirror symmetry, but satisfies only reciprocity if the medium contains chiral components. The scattering matrix was factorized by using the Lu–Chipman polar decomposition, which affords the polarization parameters as a function of the radial distance from the center. The depolarization coefficients decrease with increasing distance, whereas the scattering induced linear diattenuation and retardance become larger in the middle to long distance range. The optical rotation for a chiral medium increases with increasing distance.

Structure and EUV performance of Si/C multilayers deposited underdifferent working pressure

Zhanshan Wang, qiang yi, Qiushi Huang, xiangmei wang, Yang Yang, Xiaowei Yang, Zhong Zhang, Rongkun Xu, Taiping Peng, Hongjun Zhou, and Tonglin Huh

Doc ID: 274854 Received 30 Aug 2016; Accepted 15 Nov 2016; Posted 16 Nov 2016  View: PDF

Abstract: Narrow bandwidth Si/C multilayer mirrors are fabricated and characterized for the Z-pinch plasma diagnostic at the wavelength of 16.5 nm. To reduce the large stress of the multilayer and maintain a practical reflectivity, differentworking pressures, from 0.13 Pa to 0.52 Pa, are optimized during the deposition. The grazing incidence X-ray reflectometry (GIXR) measurement and the fitting results indicate that an interlayer was formed at the interfaces whileboth the interlayer thickness and interface widths increase with larger working pressure. The surface roughness of the multilayers also increases from 0.13 nm at 0.13 Pa to 0.29 nm at 0.52 Pa, as revealed by the atomic force microscope(AFM) measurements. The multilayer stress decreases from -682 MPa to -384 MPa, as the working pressure increases from 0.13 Pa to 0.52 Pa, respectively. The experimental EUV reflectivity of the samples with 20 bilayers graduallydecreased from 26.3% to 18.9% with increased working pressure. The bandwidth of the reflection peak remains similar for the different samples with a full width half maximum (FWHM) value of around 0.87 nm. A maximum EUVreflectivity of 33.2% and a bandwidth of 0.64 nm were achieved by the sample with 50 bilayers fabricated under a working pressure of 0.13 Pa.

Nonmechanical scanning laser Doppler velocimetry for distribution measurements of two-dimensional velocity vectors based on optical quadrature detection

Koichi Maru

Doc ID: 275892 Received 14 Sep 2016; Accepted 15 Nov 2016; Posted 16 Nov 2016  View: PDF

Abstract: This paper proposes a nonmechanical scanning laser Doppler velocimeter (LDV) for measuring the distribution of two-dimensional velocity vectors. In the proposed LDV, an optical quadrature detection technique and a nonmechanical axial scanning technique are introduced into a reference-type LDV. Consequently, the LDV has a simple optical system without multiple light sources or frequency shifting and does not have any moving mechanism in its probe. The experimental results obtained using a sensor probe setup indicate that the function of measuring two-dimensional velocity vectors and the scanning function are successfully demonstrated.

Remote Raman Measurements of Minerals, Organics and Inorganics at 430 Meter Range

Tayro Acosta-Maeda, Anupam Misra, Lloyd Muzangwa, Genesis Berlanga, Shiv Sharma, John Porter, and Dalton Muchow

Doc ID: 273184 Received 04 Aug 2016; Accepted 15 Nov 2016; Posted 15 Nov 2016  View: PDF

Abstract: Raman spectroscopy is a characterization technique that is able to analyze and detect water or water bearing minerals, minerals, and organic materials that are of special interest for planetary science. Using a portable pulsed remote Raman system with a commercial 8” telescope a frequency doubled Nd-YAG pulsed laser and a spectrometer equipped with an intensified CCD camera, we acquired good quality Raman spectra of various materials from a 430 m standoff distance during daylight with detection times of 1-10 s, in a realistic context in which both the exciting source and the detector are part of the same measurement system. Remote Raman spectra at this distance provided unambiguous detection of compounds such as water and water ice, dry ice, sulfur, sulfates, various minerals and organics, and atmospheric gases. This research work demonstrates significant improvement in the remote Raman technique as well as its suitability for Solar System exploration.

Performance of a two detector camera for real-time video

Benjamin Lochocki, Adrian Gambin, and Pablo Artal

Doc ID: 270914 Received 22 Jul 2016; Accepted 15 Nov 2016; Posted 16 Nov 2016  View: PDF

Abstract: Single Pixel Imaging can be the preferred method over traditional 2D-array imaging in spectral ranges whereconventional cameras are not available. However, when it comes to real-time video imaging, single pixel imagingcannot compete with the framerates of conventional cameras, especially when high-resolution images are desired.Here we evaluate the performance of an imaging approach using two detectors simultaneously. First, we presenttheoretical results on how low SNR affects final image quality followed by experimentally performed results.Obtained video framerates are doubled compared to state of the art systems, resulting in a frame-rate from 22Hzfor a 32 x 32 resolution through to 0.75Hz for a 128 x 128 resolution image. Additionally, the two detector imagingtechnique allows the acquisition of images with a resolution of 256 x 256 in less than 3 seconds.

Binary coded identification of industrial chemical vapors with an optofluidic nose

Mehmet Bayindir, ABUBAKAR ISA ADAMU, and FAHRI EMRE OZTURK

Doc ID: 273337 Received 08 Aug 2016; Accepted 15 Nov 2016; Posted 16 Nov 2016  View: PDF

Abstract: An artificial nose system for the recognition and classification of gas phase analytes and its application in identifying common industrial gases is reported. The sensing mechanism of the device comprises the measurement of infrared absorption of volatile analytes inside the hollow cores of optofluidic Bragg fibers. An array of six fibers is used, where each fiber targets a different region of the midinfrared in the range of 2-14 µm with transmission bandwidths of about 1-3 µm. The quenching in the transmission of each fiber due to the presence of analyte molecules in the hollow core is measured separately and the cross response of the array allows the identification of virtually any volatile organic compound (VOC). The device was used for the identification of seven industrial VOC vapors with high selectivity using a standard blackbody source and an infrared detector. The array response is registered as a unique six digit binary code for each analyte by assigning a threshold value to the fiber transmissions. The developed prototype is a comprehensive and versatile artificial nose that is applicable to a wide range of analytes.

Research on uplink CSMA algorithm of large Indoor VLC networks based on a modified hard core point process

xuefen chi and Zhufen Nan

Doc ID: 273675 Received 11 Aug 2016; Accepted 15 Nov 2016; Posted 16 Nov 2016  View: PDF

Abstract: IEEE 802.15.7 suggests that it could coordinate channel access process based on the competitive way of carrier-sensing. However, the direction of light and randomness of diffuse reflection would give rise to serious imperfect carrier sense case (ICS) problem (e.g.hidden node problem), which brings great challenges in realizing the optical carrier sense multiple access (CSMA) mechanism. It is necessary to characterize the CSMA process in visible light communication (VLC) networks. This paper abstracts indoor nodes using diffuse reflection light to complete the carrier sense process into the choice problem of independent sets based on hard core point process (HCPP). Considering the node intensity underestimation flaw of the traditional HCPP, we model the CSMA process for multi-point to multi-point VLC uplink communication systems based on a modified HCPP (MHCPP) which considers the freezing property of back-off counter. We obtain the intensity of simultaneously active light emitting diode (LED) transmitters based on the MHCPP and propose an interference model in ICS case for the VLC networks. Further we obtain the closed-form expression for approximating the outage probability and the transmission capacity of VLC networks. Simulation results validate the analysis and also show the existence of an optimal physical carrier-sensing threshold (PCST) which maximizes the transmission capacity for a given emission angle of LED

Optical receiving system based on compound parabolic concentrator and hemispherical lens for visible light communication

Yun Wang, Tian Lan, and guoqiang ni

Doc ID: 274197 Received 24 Aug 2016; Accepted 14 Nov 2016; Posted 15 Nov 2016  View: PDF

Abstract: We propose a scheme for designing a new optical receiving system that can reduce the received-energy spot-sizevia integration of a compound parabolic concentrator with a hemispherical lens. SolidWorks is used to model thereceiving system while TracePro is employed for simulations. The field of view is set to 30° and the radius of thecompound parabolic concentrator outlet is 5 mm, which is also the radius of the hemispherical lens. Ray-tracingresults show that under the given simulation conditions, the radius of the spot area is reduced from 5 to 3 mm atthe receiving system and the gain is 5.2. As regards the relations between received power and the radius of thehemispherical lens R, and the received power and the distance d between the compound parabolic concentratorand hemispherical lens, our detailed analysis yields the following characteristics:(1) the received powerincreases as R increases, but decreases as d increases; (2) as R increases, the spot area increases and the receivedflux is dispersed over the receiving plane, which dispersion is disadvantageous for high-speed communication; (3)the gain of the receiving system also varies with R and d; (4) an increase in d leads to decrease in the received fluxand gain when d > -2 mm. Based on these characteristics, we set R = 5 mm and calculate the energy efficiency. Weobtain maximum energy efficiencies for different detection areas.

Effect of spatial distribution of partial information on the accurate recovery of optical wavefields using the fractional Fourier transform

Figen Oktem and Haldun Ozaktas

Doc ID: 275197 Received 06 Sep 2016; Accepted 14 Nov 2016; Posted 15 Nov 2016  View: PDF

Abstract: We consider the problem of recovering a signal from partial and redundant information distributed over two fractional Fourier domains. This corresponds to recovering a wavefield from two planes perpendicular to the direction of propagation in a quadratic-phase multilens system. The distribution of the known information over the two planes has a significant affect on our ability to accurately recover the field. We observe that distributing the known samples more equally between the two planes, or increasing the distance between the planes, generally makes the recovery more difficult. Spreading the known information uniformly over the planes, or acquiring additional samples to compensate for the redundant information, helps to improve the accuracy of the recovery. These results shed light onto redundancy and information relations among the given data, and provides a deeper insight into the underlying mathematical problem.

Temporal resolution beyond the average pulse duration in shaped noisy-pulse transient absorption spectroscopy

Thomas Pfeifer, Kristina Meyer, Niklas Müller, and Zuoye Liu

Doc ID: 275490 Received 07 Sep 2016; Accepted 14 Nov 2016; Posted 15 Nov 2016  View: PDF

Abstract: In time-resolved spectroscopy, it is a widespread belief that the temporal resolution is determined by the laser pulse duration. Recently, it was observed and shown that partially coherent laser pulses as they are provided by Free-Electron-Laser (FEL) sources offer an alternative route to reach a temporal resolution below the average pulse duration. Here, we demonstrate the generation of partially coherent light in the laboratory like we observe it at FELs. We present the successful implementation of such statistically fluctuating pulses by using the pulse-shaping technique. These pulses exhibit an average pulse duration about ten times larger than their bandwidth limit. The shaped pulses are then applied to transient-absorption measurements in the dye IR144. Despite the noisy characteristics of the laser pulses, features in the measured absorption spectra occurring on time scales much faster than the average pulse duration are resolved, thus, proving the universality of the described noisy-pulse concept.

Fiber Bragg grating-based measurement of randomrotationparameters

Lianqing Zhu, Lidan Lu, Wei Zhuang, Hong Li, and xiaoping lou

Doc ID: 277658 Received 27 Sep 2016; Accepted 14 Nov 2016; Posted 15 Nov 2016  View: PDF

Abstract: A pre-loaded rotational sensor featuring a spring packaged within the magnetic head has been proposed andexperimentally demonstrated. The aforementioned FBG-based system can convert the strain information intorotation angles without rotation-angle limitation by a proposed angle transfer mathematical model. The randomangulardisplacements were well fitted by the model with the maximum deviation of 0.5°. The linearity of thecalculated rotational velocity reaches up to 0.998 in the range 0 to 2021.4 rpm. This sensor can also be applied inthe angular acceleration measurement.

Ge0.975Sn0.025 320 x 256 imager chip for 1.6 to 1.9 μm infrared vision

Chiao Chang, Hui Li, Chien-Te Ku, Shih-Guo Yang, Henry Cheng, Joshua Hendrickson, Richard Soref, and Gregory Sun

Doc ID: 277929 Received 06 Oct 2016; Accepted 14 Nov 2016; Posted 15 Nov 2016  View: PDF

Abstract: We report the experimental fabrication and testing of a GeSn-based 320 x 256 image sensor focal-plane array operating at -15°C in the 1.6 to 1.9 μm spectral range. For image readout, the 2D pixel array of Ge/GeSn/Ge p-i-n hetero photodiodes was flip-chip bonded to a customized silicon CMOS readout integrated circuit. The resulting camera chip was operated using back-side illumination. Successful imaging of a tungsten-filament light bulb was attained with observation of grey-scale “hot spot” infrared features not seen using a visible light camera. The Ge wafer used in the present imaging array will be replaced in future tests by a Germanium on Silicon wafer offering thin film Ge upon Si or on SiO2/Si. This is expected to increase the infrared responsivity obtained in back-side illumination, and it will allow manufacture of the imager in a Si-based foundry. Our experiments are a significant step towards realization of group-IV near-mid infrared imaging systems, such as those for night vision.

Giant Nonlinear Absorption and Excited Carrier Dynamics of Black Phosphorus Few-Layer Nanosheets in Broadband Spectra

Tian Jiang, Runze Chen, Tang Yuhua, and Xin Zheng

Doc ID: 275704 Received 13 Sep 2016; Accepted 12 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: Layered black phosphorus nanosheets (BPNs) offer potential uses in nanoelectronic and photonics applications. This work demonstrates giant saturable absorption (SA) and two-photon absorption (TPA) of BPNs under femtosecond visible-to-mid-infrared laser-pulse excitation. Meanwhile the excited carrier dynamics of BPNs were also studied through ultrafast pump probe technology. Measurements demonstrate that the nonlinear absorption properties of BPNs strongly depend on excitation wavelength and intensity. BPNs moved from SA to TPA under increasing laser intensities at 800 nm, 1160 nm, 1300 nm, and 1550 nm but showed a purely TPA response at 2000 nm, as gauged by measured BPN nonlinear absorption coefficients. The BPNs showed broadband pump-probe signal under the wavelength from 470 nm to 700 nm and the excited carrier recombination time was extracted to be 150 ± 10 ps. The excitation intensity dependence of excited carrier dynamics were also studied.

Calculation of Temperature Profiles in Solid State Laser Disks mounted on Multi-Layered Heat Spreaders using Hankel Transforms

Norman Hodgson and Andrea Caprara

Doc ID: 275810 Received 15 Sep 2016; Accepted 12 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: The main challenge in disk laser design is the realization of efficient heat removal from the pumped area by optimizing the heat spreader design and the water impingement cooling. This generally requires the calculation of the temperature distribution in the disk by numerically solving the heat conduction equation using finite element algorithms. We have developed a simple method to calculate disk temperature profiles that is based on analytically solving the heat conduction equation in Hankel Transform Space. This method can be applied to disks that are mounted on multi-layered, water-cooled heat spreaders, which may include glue or solder layers and dielectric coating layers. The temperature and heat fluxes at the interfaces of the layers are connected via a heat transfer matrix, which allows for straight-forward incorporation of additional heat sink layers or an un-doped cap into the model. This generalized model allows for the parametric optimization of the heat distribution in pumped solid state laser and semiconductor laser disks.

Modeling of edge effect in sub-aperture tool influence functions of computer controlled optical surfacing

xiangchao zhang, Songlin Wan, Xiaoying He, and Min Xu

Doc ID: 276365 Received 23 Sep 2016; Accepted 12 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: Computer controlled optical surfacing requires accurate tool influence function (TIF) for reliable path planningand deterministic fabrication. Near the edge of the workpieces, the TIF has a nonlinear removal behavior, whichwill cause severe edge-roll phenomenon. In the present paper a new edge pressure model is developed based onthe finite element analysis results. The model is represented as the product of a basic pressure function and acorrecting function. The basic pressure distribution is calculated according to the surface shape of the polishingpad and the correcting function is used to compensate the errors caused by the edge effect. Practical experimentalresults demonstrate that the new model can accurately predict the edge TIFs with different overhang ratios. Therelative error of the new edge model can be reduced down to 15%.

Ultra Broadband mid-IR Supercontinuum Generation in Ge11.5As24Se64.5 based Chalcogenide Graded-Index Photonic Crystal Fiber: Design and Analysis

Ajeet Kumar, A G N CHAITANYA, Than Singh Saini, and Ravindra Sinha

Doc ID: 272426 Received 26 Jul 2016; Accepted 12 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: In this paper, we report design and numerical analysis of Ge11.5As24Se64.5 based chalcogenide glass graded index photonic crystal fiber structure for mid-IR ultra broadband supercontinuum generation. The proposed dispersion engineered photonic crystal fiber offers zero dispersion wavelength at pump wavelength of 2.8 μm. To simulate the supercontinuum generation spectrum, the orders of dispersion coefficient upto the ninth order are considered. Simulated results indicate that an ultra broadband supercontinuum spectrum spanning 1 – 16 μm has been achieved using 10 mm long photonic crystal fiber structure pumped with 50 fs secant hyperbolic pulses of 3 kW at -30 dB spectral intensity level. To the best of our knowledge such broad supercontinuum spectrum has been reported first time. Such ultra broadband mid-IR supercontinuum spectrum is vastly applicable in different diverse fields such as medical, defense, metrology and spectroscopy.

Terahertz generation based on difference frequency generation by rotating fan-out poled LiNbO3

zhongyang li, Degang Xu, and Jian-Quan Yao

Doc ID: 273106 Received 03 Aug 2016; Accepted 12 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: Theoretical analysis of terahertz (THz) generation based on difference frequency generation (DFG) by rotating fan-out poled LiNbO3 is presented. The uncertainty of poling vectors during clockwise and counter-clockwise rotation of the fan-out poled LiNbO3 at the center of the crystal input face is investigated. Poling period along the propagation direction of the input pump and signal waves during clockwise and counter-clockwise rotation is calculated. The dependence of THz vectors on rotation angles is numerical simulated. The relative intensities of THz wave during clockwise rotation of the fan-out poled LiNbO3 are calculated.

Spectral phase effects and control requirements of coherent beam combining for ultrashort ultrahigh intensity laser systems

YAN-QI Gao, Yong Cui, Zexi Zhao, Zhongyang Xu, Ning An, D Li, Jianwei Yu, TAO WANG, Guang Xu, WEI-XIN MA, and Yaping Dai

Doc ID: 274830 Received 02 Sep 2016; Accepted 12 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: Based on the premise that further improvements of the size and damage threshold of large-aperture optical components are limited severely, coherent beam combining (CBC) is a most promising way to scale up the available peak-power of pulses for ultrashort ultrahigh intensity laser systems. Spectral phase effects are important issues and have significant impact on the performance of CBC. In this work, we analyze systematically the factors including spectral dispersions and longitudinal chromatism, and get the general spectral phase control requirements of CBC for ultrashort ultrahigh intensity laser systems. It is demonstrated that different orders of dispersion influence intensity shape of the combined beam, and high order dispersions affect the temporal contrast of the combined beam, while the number of the channels to be combined has little impact on the temporal Strehl ratio (SR) of the combined beam. In addition, longitudinal chromatism should be controlled effectively since it has detrimental effect on the combined beam at the focal plane both temporally and spatially.

Guide to quickly build high-quality 3D models with a structured light range scanner

Bao-Quan Shi and jin liang

Doc ID: 275277 Received 06 Sep 2016; Accepted 11 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: In literature, there are many reports about how to build high-precision, high-speed and/or flexible structured light range scanners. Whereas, there are few papers reported about how to implement the scanning to reach the full potential of the scanners when digitizing various objects. In this paper, some scanning strategies adopted by the structured light range scanner XJTUOM are introduced. In order to build high-quality 3D models for various applications such as 3D inspection, if necessary, the object surface is prepared by application of coating spray in advance. Then, a precise 3D coordinate control network (CNN) is established to control the overall measurement accuracy. When the sensor is adjusted to face the object, a visual measuring volume which can guide the scanning is automatically aligned to the established CNN. Meanwhile, to maintain the local region scanning accuracy, simple rules are developed to check the low-quality regions in each scanning. Finally, the advantages and limitations of these scanning strategies are discussed in detail. And we hope our work will be helpful for others to make their own scanning plans with similar optical devices at hand.

Transient features and growth behavior of the artificial cracks during the initial damage period

Bin Ma, Ke Wang, Menglei Lu, Li Zhang, lei zhang, Jinlong Zhang, Xinbin Cheng, and Zhanshan Wang

Doc ID: 274676 Received 29 Aug 2016; Accepted 11 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: The laser damage of transmission elements contains a series of complex processes and physical phenomena. The final morphology is a crater structure with different sizes and shapes. The formation and development of the crater are also accompanied by the generation, extension, and submersion of cracks. The growth characteristics of craters and cracks are important in the thermal–mechanism damage research. By using pump–probe detection and imaging technique with nanosecond pulse width probe laser, we obtained the formation time of crack structure in radial and circumferential direction. We carried out statistical analysis in angle, number, and crack length. We further analyzed the relationship between cracks and stress intensity or laser irradiation energy as well as the crack evolution process and the inner link between cracks and pit growth. We used artificial indentation defect to investigate the time-domain evolution of crack growth, growth speed, transient morphology, and characteristics of crater expansion. Results can be used to elucidate thermal stress effects on cracks, time-domain evolution of damage structure, and damage growth mechanism.

Liquid crystal grating-based optical displacement sensors

Michinori Honma, Tatsuya Miura, and Toshiaki Nose

Doc ID: 272588 Received 28 Jul 2016; Accepted 11 Nov 2016; Posted 11 Nov 2016  View: PDF

Abstract: Optical properties of liquid crystal (LC) gratings with a mobile glass substrate, which can be used for optical displacement applications, were investigated. The LC gratings are composed of homogeneous and twisted nematic domains. The displacement measurement principle is based on the diffraction efficiency change induced by varying the mixing ratio of two orientation domains in response to the lateral shift of the mobile substrate. Improved conditions for the polarization of incident light direction as well as the application of a voltage for achieving higher sensitivities were explored. A simple demonstration of an LC-grating-based displacement sensor was also conducted.

Nonlinear Optical Characterization of Multinuclear Iridium Compounds Containing Tricycloquinazoline

William Shensky, Michael Ferry, Jianmin Shi, Trenton Ensley, and Ryan O'Donnell

Doc ID: 272730 Received 05 Aug 2016; Accepted 11 Nov 2016; Posted 11 Nov 2016  View: PDF

Abstract: Nonlinear optical properties were characterized for a series of multinuclear iridium compounds of the form TCQ[Ir(ppz)₂]n , where n = 1, 2, or 3, TCQ is tricycloquinazoline and ppz is 1-phenylpyrazole. Transient absorption (TA) spectroscopy indicated that the triplet metal-to-ligand charge transfer (³MLCT) excited state was formed on the sub-ps timescale and decayed back to the ground state on the μs timescale, consistent with literature precedent. TA bands were observed for all three compounds from 475-900 nm, implying the potential for reverse-saturable absorption (RSA) at those wavelengths. Z-scan measurements using ps and ns pulses were obtained at 532 nm and confirmed the presence of RSA behavior for all three compounds. The triplet excited state cross sections and the RSA figure of merit were found to decrease with increasing n: 1 > 2 ~ 3.

Multi-exposure imaging and parameter optimization for intensified star trackers

Jie Jiang, Wenbo Yu, and Guangjun Zhang

Doc ID: 270696 Received 18 Jul 2016; Accepted 11 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: Due to the introduction of the intensified image detector, the dynamic performance of the intensified star tracker is effectively improved. However, its attitude update rate is still seriously restricted by the transmission and processing of pixel data. In order to break through the above limitation, a multi-exposure imaging approach for intensified star trackers is proposed in this paper. One star image formed by this approach actually records N different groups of star positions, and then N corresponding groups of attitude information can be acquired. Compared with the existing exposure imaging approach, the proposed approach improves the attitude update rate by N times. Furthermore, for a dim star, the proposed approach can also accumulate the energy of its N positions and then effectively improve its signal to noise ratio (SNR). Subsequently, in order to obtain the optimal performance of the proposed approach, parameter optimization is carried out in this paper. Firstly the motion model of the star spot in the image plane is established, and then based on it, all the key parameters are optimized. Experimental results demonstrate the feasibility and effectiveness of the proposed approach and parameter optimization.

Multi-Octave Metamaterial Reflective Half-Wave Plate for Millimetre and Sub-Millimetre wave Applications

Giampaolo Pisano, Bruno Maffei, Peter Ade, Paolo de Bernardis, Peter de Maagt, Brian Ellison, Manju Henry, Ming Wah Ng, Brian Schortt, and Carole Tucker

Doc ID: 276306 Received 21 Sep 2016; Accepted 11 Nov 2016; Posted 14 Nov 2016  View: PDF

Abstract: The quasi-optical modulation of linear polarization at millimeter and sub-millimeter wavelengths can be achievedby using rotating half-wave plates (HWPs) in front of polarization sensitive detectors. Large operationalbandwidths are required when the same device is meant to work simultaneously across different frequency bands.Previous realizations of half-wave plates, ranging from birefringent multi-plates to mesh-based devices, haveachieved bandwidths of the order of 100%. Here we present the design and experimental characterization of areflective HWP able to work across bandwidths of the order of 150%. The working principle of the novel device iscompletely different from any previous realization and it is based on the different phase-shift experienced by twoorthogonal polarizations reflecting respectively off an electric conductor and an artificial magnetic conductor.

Ultra-broad band and low dispersion engineered slow light using liquid infiltration of modified photonic crystal waveguide

Arash Karimkhani, Mohammad Pourmand, and Fakhroddin Nazari

Doc ID: 275500 Received 07 Sep 2016; Accepted 10 Nov 2016; Posted 11 Nov 2016  View: PDF

Abstract: We present an ultra-broad band and low dispersion slow light photonic crystal waveguide with large normalized delay−bandwidth product that can be exploited in many ultra-compact all optical devices such as modulators and switches. The new proposal approach is based on infiltrating optical fluid into the first and second rows of shifted air holes adjacent to the waveguide which is made as line defect in a hexagonal lattice of photonic crystal. The simulation results show that the normalized delay−bandwidth product can enhance to a large value of 0.469 with wide bandwidth operation of 36.8 nm in the C band frequency optical communication window. Furthermore, by means of the finite-difference time-domain calculations, the low dispersion slow light propagation is approved by simulating the temporal Gaussian pulse width broadening.

Stress Control in Optical Thin Films by Sputtering andElectron Beam Evaporation

Naoya Tajima, Hiroshi Murotani, Shigeharu Matumoto, and Hiromitsu Honda

Doc ID: 274859 Received 30 Aug 2016; Accepted 10 Nov 2016; Posted 10 Nov 2016  View: PDF

Abstract: It is necessary to control the internal stress of optical thin films in order to address problems such as peeling andcracking. Internal stress differs among films prepared by different deposition methods. We investigated theinternal stress of films prepared by sputtering, electron beam (EB) evaporation, and a combination depositionmethod that we developed. The internal stress was successfully controlled, showing a value between that of EBevaporation and sputtering.

Measurement of surface form error of an optical surface with reduced interferometric spatial coherence artifacts using a ring source and polarization phase shifting interferometry.

Pavan Y, sarvendra singh, M Kamath, Sanjib Chatterjee, and S Sharma

Doc ID: 268161 Received 13 Jun 2016; Accepted 09 Nov 2016; Posted 10 Nov 2016  View: PDF

Abstract: We present a technique for the measurement of surface form error of an optical surface using a ring source and polarization phase shifting interferometry (PPSI). The ring source, generated using a refracting axicon, is projected onto a rotating diffuser (RD) to reduce the spatial coherence noise generated by the spatially coherent He-Ne laser and to enhance the interference fringe contrast. PPSI is applied to extract the phase (and hence the optical path difference (OPD)) from the interference fringes formed by a Fizeau cavity using the ring source. The OPD values are least-square fitted to a plane and the surface form errors are evaluated from the deviations of the OPD values from the fitted reference plane. The main advantage of the technique is that the perturbations in the Fizeau cavity are negligible during the phase shifts as the phase shifts between the interfering beams are introduced outside the cavity.

First mesospheric wind images using the Michelson Interferometer for Airglow Dynamics Imaging (MIADI)

Jeffery Langille, William Ward, and Takuji Nakamura

Doc ID: 274122 Received 30 Aug 2016; Accepted 09 Nov 2016; Posted 09 Nov 2016  View: PDF

Abstract: The Michelson Interferometer for Airglow Dynamics Imaging (MIADI) is a ground based instrument that combines an imaging capability with Doppler Michelson Interferometry in order to remotely detect motions in the mesopause region using spectrally isolated airglow emissions: the O(1S) emission at 557.73 nm and the and OH (6, 2) P1 (2) at 839.918 nm. A measurement and analysis approach has been developed that allows simultaneous images of the line of sight Doppler wind field and irradiance field to be obtained. A working field instrument was installed and tested at a field site outside Fredericton, NB (45.96 N, 66.65 W) during the summer of 2014. Successful measurements over a six hour period were obtained on July 31, 2014. This paper describes the MIADI measurement and analysis approach and presents the work that has been done to extract images of the line of sight Doppler wind field and irradiances from these observations. The imaging capability is validated by identifying the presence of large scale and small scale geophysical perturbations in the images.

Research on the mechanical stability of high laser resistant coatings on Lithium triborate crystal

Jinlong Zhang, xiaoqing bu, Bin Ma, Hongfei Jiao, Xinbin Cheng, and Zhanshan Wang

Doc ID: 274868 Received 30 Aug 2016; Accepted 09 Nov 2016; Posted 09 Nov 2016  View: PDF

Abstract: The thermo-mechanical property of the hafnia/silica anti-reflection(AR) coatings on Lithium triborate(LBO) crystal was investigated by simulation and experiment. From the analysis of the stress and fracture toughness, it was found that the crack originated due to the high tensile stress in hafnia coating. Then we proposed the approaches of decreasing the deposition temperature and substituting the hafnia layers with alumina to improve the mechanical stability of AR coatings on LBO crystals, and cracks were effectively suppressed. The laser damage threshold of different coatings on LBO crystal was tested, and it illustrated that the alumina/silica coating possess better laser resistance than hafnia/silica AR coatings deposited in low deposition temperature.

Polarimetric characteristics of a class of hyperspectral radiometers

Marco Talone and Giuseppe Zibordi

Doc ID: 275371 Received 07 Sep 2016; Accepted 08 Nov 2016; Posted 09 Nov 2016  View: PDF

Abstract: The polarimetric characteristics of a class of hyperspectral radiometers commonly applied for above-water radiometry have been investigated by analyzing a sample of sensors. Results indicate polarization sensitivity increasing with wavelength and exhibiting values varying from sensor to sensor. In the case of irradiance sensors, the maximum differences between horizontal and vertical polarization sensitivities vary from approximately 0.3% at 400 nm to 0.6% at 750 nm. In the case of radiance sensors, the maximum differences increase from approximately 0.4% at 400 nm to 1.3% at 750 nm. Application of the previous results to above-water radiometry measurements performed in different water types indicates that neglecting polarization effects may lead to uncertainties not exceeding a few tenths of percent in remote sensing reflectance RRS determined in the 400-570 nm spectral interval. Conversely, uncertainties spectrally increase toward the near infrared, reaching several percent at 750 nm in the case of oligotrophic waters.

Highly nonlinear polarization-maintaining photonic crystal fiber with nanoscale GaP strips

Mohammad Faisal and Md Nafiz Amin

Doc ID: 277543 Received 27 Sep 2016; Accepted 08 Nov 2016; Posted 09 Nov 2016  View: PDF

Abstract: A highly birefringent silica photonic crystal fiber is proposed with nano-scale gallium phosphide strips at the core and modified spiral cladding air hole distribution. Optical properties of the PCF are simulated using finite element method. Significant influences of low refractive index slot region confinement and high index strips confinement are observed for two different modes. This introduces a high birefringence of ~0.58 at 1.55 µm wavelength. Moreover, high nonlinearity coefficient of the order ~10⁴ W¨¹km¨¹ is achieved in the wavelength range from 1.4 to 1.7 µm. The proposed fiber will find promising applications in coherent optical communications and sensing applications.

Multi-stage Classification Method Oriented to AerialImage Based on Low Rank Recovery and Multi-featureFusion Sparse Representation

Hao Shuai, Ma Xu, and Cheng Yongmei

Doc ID: 274340 Received 23 Aug 2016; Accepted 08 Nov 2016; Posted 09 Nov 2016  View: PDF

Abstract: Automatic classification of terrain surfaces from aerial image is essential for an Unmanned Aerial Vehicle (UAV)landing at an unprepared site autonomously by using vision. Diverse terrain surfaces may show similarspectral properties due to the illumination variations and noises, which easily causes poor classificationperformance. To address this issue, a multi-stage classification algorithm based on low rank recovery andmulti-feature fusion sparse representation is proposed. Firstly, color moments and Gabor texture feature areextracted from training data and stacked as column vectors of a dictionary. Then we perform low rank matrixrecovery for the dictionary by using augmented Lagrange multipliers (ALM) and construct a multi-stageterrain classifier. Experimental results on an aerial map database prepared by our own verify the classificationaccuracy and robustness of the proposed method.

Complex amplitude reconstruction for dynamic beam quality M2 factor measurement with self-referencing interferometer wavefront sensor

Yongzhao Du, Yuqing Fu, and Lixin Zheng

Doc ID: 272628 Received 27 Jul 2016; Accepted 08 Nov 2016; Posted 09 Nov 2016  View: PDF

Abstract: A real-time complex amplitude reconstruction method for determining dynamic beam quality M2 factor based on aMach-Zehnder self-referencing interferometer wavefront sensor is developed. By using the proposed complexamplitude reconstruction method, full characterization of laser beam, that is both amplitude (intensity profile) andphase information can be reconstructed from a single interference pattern with Fourier fringe pattern analysismethod in one-shot measurement. With the reconstructed complex amplitude, the beam fields at any position zalong its propagation direction can be obtained firstly by utilizing the diffraction integral theory. Then the beamquality M2 factor of the dynamic beam is calculated according to the specified method of the Standard ISO11146.The feasibility of the proposed method is demonstrated with the theoretical analysis and experiment including thestatic and dynamic beam process. The experimental method is simple, fast and operates without movable parts,which is allowed to investigate laser beam in conditions inaccessible which using existing methods.

Accurate Testing of Aspheric Surfaces Using the Transport of Intensity Equation by Properly Selecting the Defocusing Distance

Ahmad Darudi, Peyman Soltani, George Nehmetallah, Ali-Reza Moradi, and Javad Amiri

Doc ID: 272215 Received 22 Jul 2016; Accepted 08 Nov 2016; Posted 08 Nov 2016  View: PDF

Abstract: In the last decade, the transport of intensity has been increasingly used in microscopy, wavefront sensing, and metrology. In this study, we verify by simulation and experiment the use of the Transport of Intensity Equation (TIE) in the accurate testing of optical aspheric surfaces. Guided by simulation results and assuming that the experimental setup parameters and the conic constants are known, one can estimate an appropriate defocusing distance ∆z that leads to an accurate solution of the TIE. In this paper, this method is verified through the construction of an on-nulled experiment for testing the 2D profile of an aspheric surface. The theoretical method and experimental results are compared to validate the results. Finally, to validate the TIE methodology, the phase distribution obtained by TIE is compared with the phase distribution obtained by a Shack-Hartmann sensor.

Naturalness Index for Tone-mapped High Dynamic Range Image

Gangyi Jiang, Yang Song, Mei Yu, yun zhang, Feng Shao, and Zongju Peng

Doc ID: 273210 Received 05 Aug 2016; Accepted 08 Nov 2016; Posted 08 Nov 2016  View: PDF

Abstract: High dynamic range (HDR) images can only be backward-compatible with existing low dynamic range (LDR) imaging systems after being processed by tone-mapping operators (TMOs). Hence, the quality assessment (QA) of tone-mapped HDR images has become an important and challenging issue in HDR imaging research. In this paper, we propose a naturalness index for tone-mapped image to predict its quality. First, we extract the statistical features of the tone-mapped image’s luminance value and use it to evaluate the brightness naturalness with no reference information. Meanwhile, we use perceptive color, image contrast, and detail information to represent the image content and predict their naturalness qualities respectively. Then, four component of naturalness qualities are combined to yield the overall naturalness quality of the tone-mapped image. Experimental results on a publicly available database demonstrated that, in comparison with tradition LDR We conducted experiments using a publicly available tone-mapped image database to compare the proposed method with traditional LDR image QA methods and leading tone-mapped image QA methods, the proposed method achieves better consistency in alignment with subjective quality.

Design of Non-cooled Fiber Collimator for Compact High Efficiency Fiber Laser Arrays

Leonid Beresnev, R. Andrew Motes, Keith Townes, Patrick Marple, Kristan Gurton, Anthony Valenzuela, Chatt Williamson, Jony Liu, and Chris Washer

Doc ID: 273927 Received 16 Aug 2016; Accepted 08 Nov 2016; Posted 08 Nov 2016  View: PDF

Abstract: A high power fiber laser collimator and array of such collimators are described with optical architecture, allowing one to transmit almost 100% of the full power generated with fiber facets. In the case of coherent beam combining, more than 70% of the full power can be focused into a diffraction limited spot determined by the diameter of the conformal aperture. The aperture truncated beam tails of the periphery area of divergent (Gaussian) beams are not trapped inside of the array, but are re-directed through the output lenses and dispersed outside of the array along with the main collimated beam, thus terminating the necessity of cooling the array. Detailed analysis is presented for the beam tail propagation geometry’s dependence on parameters of the array optics including the interior re-directing lenses. The parasitic scattering from imperfections of the interior lenses is estimated to be as small as a few Watts at a power 1.5-2kW emitted by each fiber facet.

Single-mode large-mode-area laser fiber with ultra-low numerical aperture and high beam quality

Kun Peng, Huan Zhan, Li Ni, Long Wang, Yuying Wang, Cong Gao, Yuwei Li, Jian Wang, Feng Jing, and Aoxiang Lin

Doc ID: 275254 Received 06 Sep 2016; Accepted 07 Nov 2016; Posted 08 Nov 2016  View: PDF

Abstract: By using chelate precursor doping technique, we report on an ytterbium-doped aluminophosphosilicate large-mode-area fiber with ultra-low numerical aperture of 0.036 and effective fundamental mode area of ~550 m2. With a bend diameter of 600 mm, the bending loss of fundamental mode LP01 was measured to be ˂10-3dB/m in agreement with the corresponding simulation results, while that of higher order mode LP11 is >100dB/m at 1080 nm. Measured in an all-fiber oscillator laser cavity, 592 W single-mode laser output was obtained at 1079.64 nm with high beam quality M2 of 1.12. The results indicate that chelate precursor doping technique is a competitive method for ultra-low numerical aperture fiber fabrication which is very suitable to develop single-mode seed laser for high power laser system.

Higher-Q factor and higher extinction ratio with lower detection limit PhC-PISA for on-chip optical multiplexing sensing

Huiping Tian, jian zhou, Lijun Huang, Zhongyuan Fu, and Fujun Sun

Doc ID: 270896 Received 19 Jul 2016; Accepted 07 Nov 2016; Posted 08 Nov 2016  View: PDF

Abstract: We introduce an alternative method to establish nanoscale sensor array based on photonic crystal (PhC) slab, which is referred as a 1×4 monolithic PhC parallel integrated sensor array (PhC-PISA). In order to realize this functional architecture design, four lattice-shifted resonant cavities are butt-coupled to four output waveguide branches, respectively. By shifting the first to two closest neighbor holes around the defect, high-Q factor over 1.5×104 has been obtained. Owing to the slightly different cavity spacing, each PhC resonator shows an independent resonant peak shift as the refractive index changes surrounding the resonant cavity. The specific single peak with well-defined extinction ratio exceeds 25 dB. Applying finite-difference time-domain (FDTD) method, the simulations demonstrate that the sensitivity of each PhC-based sensor in PhC-PISA S1 = 60.500 nm/RIU, S2 = 59.6 nm/RIU, S3 = 62.500 nm/RIU, and S4 = 51.142 nm/RIU (refractive index unit) is achieved, respectively. In addition, the negligible crosstalk and detection limit as small as 1×10-4 have been observed. The proposed sensor array as a desirable platform has a great potential to realize optical multiplexing sensing and high-density monolithic integration.

Slow Light in Narrow Core Hollow Optical Waveguide with Low loss and Large Bandwidth

harpinder kang, Mukesh Kumar, and Varun Kumar

Doc ID: 278132 Received 05 Oct 2016; Accepted 06 Nov 2016; Posted 07 Nov 2016  View: PDF

Abstract: A narrow core hollow waveguide with low-loss is proposed which exhibits slow light characteristics. The slow light is guided in air between the top and bottom mirrors each based on high-index contrast gratings (HCGs) The proposed design shows a low propagation loss of 1.8 dB/cm at a 1-µm thick narrow air-core and the loss remains low for a broad range of wavelengths from 1200 to 1600 nm Also, the flatband slow light is realized at a grating period of 0.8 µm in 1-µm thick narrow air-core. Further design-analysis reveals a large fabrication tolerance of the proposed hollow structure with respect to grating period.

Talbot diffraction and Fourier filtering for phase locking an array of lasers

Chene Tradonsky, Nir Davidson, Asher Friesem, Ronen Chriki, and Vishwa Pal

Doc ID: 272698 Received 28 Jul 2016; Accepted 05 Nov 2016; Posted 07 Nov 2016  View: PDF

Abstract: Talbot diffraction together with Fourier filtering are incorporated into a degenerate laser cavity to demonstrateefficient and controlled phase locking of hundreds of coupled lasers, formed in different geometries and havingdifferent phase distributions. Such a combined approach leads to higher efficiency, better control and greatervariety of output phase distributions than would be possible with either separately. Simulated and experimentalresults for square, triangular and honeycomb laser array geometries are presented.

Multiplex Coherent Anti-Stokes Raman Scattering (MCARS) Spectroscopy for Trace Chemical Detection

Sherrie Pilkington, Stephen Roberson, and Paul Pellegrino

Doc ID: 272829 Received 01 Aug 2016; Accepted 05 Nov 2016; Posted 07 Nov 2016  View: PDF

Abstract: Trace chemical detection is a particularly challenging problem of significant Army interest. Optical diagnostic techniques offer rapid, accurate, sensitive, and highly selective detection of hazardous materials in a variety of systems. Multiplex Coherent Anti-Stokes Raman Scattering (MCARS) spectroscopy generates a complete Raman spectrum from the material of interest using a combination of a supercontinuum pulse which drives multiple molecular vibrations simultaneously and a narrowband probe pulse. In this study, we have demonstrated the ability of MCARS to detect trace amounts of both explosive materials and chemical warfare agent simulants at limits of detection below 0.2ng and 0.1nl, respectively. Integration times were on the order of 10ms, using a compact USB spectrometer. Characteristics of supercontinuum generation have been studied and compared to results in the literature. Finally, an algorithm which utilizes a combination of the maximum entropy method and advanced Fourier filtering to analytically remove the non-resonant background from the MCARS spectra without any a priori knowledge of the vibrational spectrum of the material of interest.

Angle tolerant hybrid plasmonic filters for visible light communications

Noha Anous, Mohamed Abdallah, Tarek Ramadan, Khalid Qaraqe, and Diaa Khalil

Doc ID: 274731 Received 30 Aug 2016; Accepted 04 Nov 2016; Posted 07 Nov 2016  View: PDF

Abstract: This work presents a novel design of a hybrid plasmonic transmission blue filter for visible light communication systems that employ yellow phosphor-coated blue light emitting diodes (LEDs). The proposed filter balances the trade-off between transmission performance and tolerance, to variation in angles of incidence (AOI), together while maintaining a low cost with limited complexity design. The designed filter operation is based upon quasi-plasmon mode excitation in a hybrid structure of alternating layers of silver (Ag) and titanium dioxide (TiO₂) over a silica substrate. A primary design approach for a hybrid plasmonic filter of five alternating layers is illustrated in detail. Needle optimization technique is further applied to achieve the required filter performance. The designed filter has an insertion loss of ~1dB over a spectral range of 400-485 nm for a wide range of AOI (slightly above 50°). The tolerance of the proposed design against fabrication errors is also tested. The performance of the proposed filters are tested for individual and simultaneous variations from the designed thicknesses, with a ±10% standard deviations from each layer’s thickness.

Long-term Time Dependence of Internal Stress in Lanthanum Titanium Oxide (H4) Optical Thin Films

Masashi Takegami, Hiroshi Murotani, and Ryota Nakano

Doc ID: 274858 Received 31 Aug 2016; Accepted 04 Nov 2016; Posted 07 Nov 2016  View: PDF

Abstract: The time variation in the internal stress of optical thin films composed of lanthanum titanium oxide (H4) deposited by ion-beam assisted deposition (IAD) and electron beam deposition was observed over a period of 10 years after deposition, and it was found that the internal stresses in the optical thin films can be controlled by optimizing the IAD conditions. Both tensile stress and compressive stress could be created by IAD, and the chemical bonding state of Ti may affect the stress behavior. The network size of the chemical bonds may affect the stress direction.

Fabrication of the broadband absorbing coatings for ASE suppression

Hongfei Jiao, Yu He, Ganghua Bao, Jinlong Zhang, Bin Ma, Xinbin Cheng, and Zhanshan Wang

Doc ID: 274861 Received 30 Aug 2016; Accepted 04 Nov 2016; Posted 07 Nov 2016  View: PDF

Abstract: Amplified spontaneous emission (ASE) is a critical factor which limits the output power of slab lasers. In order to suppress the ASE effect in slab lasers, this paper proposes an approach: a metal/dielectric broadband absorbing coating between the laser gain medium and the metal heat sink is adopted to suppress the ASE from 0 degree to 53 degree. Based on accurate characterization of Cr metal thin films, Cr/SiO2 broadband absorbing films for 1064nm YAG slab lasers are designed and fabricated to suppress ASE. The good agreement between experimental and design shows the reliability to suppress the ASE in slab lasers.

Strategies to increase laser damage performance of Ta₂O₂/SiO₂ Mirrors by Modifications of the Top Layer Design

Carmen Menoni, Drew Schiltz, Dinesh Patel, Cory Baumgarten, Brendan Reagan, and Jorge Rocca

Doc ID: 274983 Received 31 Aug 2016; Accepted 04 Nov 2016; Posted 04 Nov 2016  View: PDF

Abstract: Ta₂O₅/SiO₅ high reflection (HR) interference coatings for λ¨1 µm offer superior performance at high irradiance conditions. However, these coatings are not good candidates for high peak power conditions in comparison to HfO₂/SiO₂ multilayer stacks. Here we show that the modification of the top layers design of a quarter wave Ta₂O₅/SiO₅ high reflector leads to 4-5 fold increase in the laser damage fluence compared to a quarter wave (Ta₂O₂/SiO₂)¹⁵ when tested at λ=1.03 µm using pulse durations of 0.19 and 4 ns and peak power densities of 43.5 and 216 GW/cm². One of the designs, achieved a laser damage threshold fluence of 174 J/cm² at 4 ns which is 10% higher than that of a HfO₂/SiO₂ quarter-wave design.

Varying stress of SiOxCy thin films that are deposited by plasma polymerization

Wei-Bo Liao, Ya-Chen Chang, Cheng-Chung Jaing, CHING-LONG CHENG, Cheng-Chung Lee, Hung-Sen Wei, and Chien-Cheng Kuo

Doc ID: 274938 Received 31 Aug 2016; Accepted 04 Nov 2016; Posted 10 Nov 2016  View: PDF

Abstract: SiOxCy thin films were deposited by plasma polymerization. The stress of the deposited SiOxCy thin films can be modified by adjusting the beam current, the anode voltage and the flow rate of hexamethyldisiloxane(HMDSO) gas and oxygen. Reducing the beam current or increasing the flow rate of HMDSO gas increased the linear/cage structure ratio and turned the stress of the SiOxCy thin films from compressive to tensile. The linear/cage structure ratio can be adjusted by changing the composite parameter, W[FM]c/[FM]m to control the stress of the deposited plasma polymer films. Multilayers, TiO2/SiO2/TiO2 were coated on a SiOxCy plasma polymer film herein, reducing their stress by 70 % from 0.06 GPa to 0.018 GPa.

A new key based on tilted lenses for optical encryption

Vicente Mico, Ignacio Moreno, Zeev Zalevsky, and Carlos Ferreira

Doc ID: 272600 Received 29 Jul 2016; Accepted 03 Nov 2016; Posted 04 Nov 2016  View: PDF

Abstract: A novel concept based on tilted spherical lenses for optical encryption using Lohmann’s type I systems ispresented. The tilt angle of the spherical lenses is used as encrypted key and the decryption performance is studiedboth qualitatively (visual image degradation) and quantitatively (MSE analysis) by numerical simulations. Thepaper presents a general mathematical framework in virtue of the dioptric power matrix formalism and obliquecentral refraction used in optometry field. Computer simulations show that image information cannot be retrievedafter a few degrees of tilt on both spherical lenses in the encryption system. In addition, a preliminary experimentin presented considering a hybrid encryption/decryption process where the image is numerically encrypted butoptically decrypted. The tilt in the lenses should be understood as a complementary key to the classicalencryption/decryption process to increase the security.

Photo-sensitivity of Te-doped silicon photodiodes fabricated using femtosecond-laser irradiation

Zhiming Wu, Rui Li, Lingyan Du, Fei Tang, and Yadong Jiang

Doc ID: 274550 Received 26 Aug 2016; Accepted 02 Nov 2016; Posted 10 Nov 2016  View: PDF

Abstract: Micro-structured Te-doped silicon is prepared via femtosecond-laser irradiating Si coated with Si-Te bilayer films and photodiodes are successfully fabricated from this material. The samples are thermal annealed at 773K for three different time durations. The effects of annealing time on microstructures, infrared absorptance and photo-sensitivity of Te-doped silicon are investigated. From the scanning electronic microscope images and the optical absorptance spectra, the results show that the infrared absorptance decreases with the increase of annealing time durations, while the infrared photo-response follow an opposite tendency. At 1064 nm, the responsivity achieves 2.4836 A/W at −10 V reverse bias for the Te-doped silicon photodiode annealed at 775 K for 2 hours, which is higher than that of usual commercial Si photodiode. These results are important for the fabration of Te-doped silicon and facilitate its application in infrared detectors.

Effects of acute hypoxic exposure on oxygen affinity of human red blood cells

Raktim Dasgupta and Aniket Chowdhury

Doc ID: 268848 Received 20 Jun 2016; Accepted 01 Nov 2016; Posted 01 Nov 2016  View: PDF

Abstract: Adaptation of red blood cells (RBCs) subjected to acute hypoxia, crucial for managing high altitude syndrome and pulmonary diseases, has been investigated. For this RBCs were exposed to acute hypoxic condition by purging nitrogen over increasing time periods from 15 minutes to 60 minutes and thereafter equilibrated with atmospheric oxygen for 10 minutes. Raman spectra of these RBCs were then recorded and analysed to look for changes in the level of oxygenation compared to unexposed cells. A decreasing oxygen affinity for the cells was observed with increasing time of exposure to hypoxic condition. This change in oxygen affinity for the RBCs may result from metabolic adjustment of the cells under hypoxic condition to promote increased concentration of intracellular 2, 3-diphosphoglycerate.

Reactive Dynamics Analysis of Critical Nb2O5 Sputtering Rate for Drum Based Metal-like Deposition

Shigeng Song, CHENG LI, Hin On Chu, and Des Gibson

Doc ID: 274926 Received 30 Aug 2016; Accepted 11 Oct 2016; Posted 11 Oct 2016  View: PDF

Abstract: Drum based metal-like film deposition for oxide was investigated using single wavelength in-situ monitoring. The data was used to investigate oxidation mechanism using combined second order kinetic and parabolic models. A critical Nb2O5 deposition rate of 0.507nm/s was found at drum rotation 1rev/s. However, N2O5 samples prepared at varying deposition rates showed deposition rate must be much lower than critical deposition rate to achieve reasonable absorption. Thus simulation for volume-fraction of metal in oxide layer was done using EMA and distribution function. Simulation gave high agreement with experimental results, and allows prediction of extinction coefficients at various deposition rates.

Optical Interference Coating Design Contest 2016: A Dispersive Mirror and Coating Uniformity Challenge.

Jennifer Kruschwitz, Vladimir Pervak, Jason Keck, Ilya Bolshakov, Zachary Gerig, Fabien Lemarchand, Kageyuki Sato, William Southwell, Muneo Sugiura, Michael Trubetskov, and Wenjia Yuan

Doc ID: 274497 Received 25 Aug 2016; Accepted 07 Oct 2016; Posted 01 Nov 2016  View: PDF

Abstract: A dispersive mirror and a coating uniformity challenge were the topics of the design contest held in conjunction with the 2016 Optical Interference Coatings topical meting of the Optical Society of America. A total of 18 designers from China, France, Germany, Japan, and the United States submitted 38 total designs for problems A and B. Michael Trubetskov submitted the winning designs for all four design challenges. The design problems and the submitted solutions are described and evaluated.

Dependence of depth of focus on spherical aberration of optical systems

Antonin Miks and Jiri Novak

Doc ID: 267338 Received 31 May 2016; Accepted 05 Jul 2016; Posted 06 Jul 2016  View: PDF

Abstract: This paper presents a theoretical analysis and computation of aberration coefficients of the third and fifth order of transverse spherical aberration of an optical system, which generates a ray bundle with a diameter of a geometric-optical circle of confusion smaller than a predetermined limit value. Equations were derived for the calculation of aberration coefficients of an optical system, which satisfy given conditions, and for the determination of the maximum possible depth of focus for given conditions.

Select as filters


    Select Topics Cancel
    © Copyright 2016 | The Optical Society. All Rights Reserved