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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.

Chalcogenide-Based Optical Parametric Oscillator at 2 μm

lizhu Li, Martin Rochette, and Nurmemet Abdukerim

Doc ID: 269188 Received 28 Jun 2016; Accepted 26 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: We report the first chalcogenide-based optical parametric oscillator (OPO) relying on pure parametric gain. The all-fiber OPO operates in the wavelength range of 2 µm and is tunable over 290 nm from the combined Stokes and anti-Stokes contributions. The gain medium is a 10 cm long chalcogenide microwire made out of a high modal confinement As₂Se₃ core with COP polymer cladding, leading to optimized chromatic dispersion, high nonlinearity, and broadband transparency. With a power threshold of only a fraction of milliwatt, this design is promising for the fabrication of tunable, compact, and low-power consumption mid-infrared sources.

Single-shot multidirectional self-imaging free 3-beam grating interferometry for extended range wave front sensing

Maciej Trusiak, Lukasz Sluzewski, and Krzysztof Patorski

Doc ID: 270055 Received 07 Jul 2016; Accepted 26 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: Crossed grating three-beam lateral shearing interferometry for extended range wave front sensing is presented. A Fresnel diffraction pattern of two multiplicatively superimposed linear diffraction gratings each generating three diffraction orders is recorded. A simple solution employs common crossed binary amplitude Ronchi grating with spatial filtering. Digital processing of single-shot pattern includes separating multidirectional pairs of orthogonal lateral shear interferograms, retrieving second harmonics of their intensity distribution and calculating shearing phase distributions. Single frame automatic fringe pattern processing based on the Hilbert-Huang transform is used for this purpose. Using second harmonics extends the aberration measurement range since they encode self-imaging free two-beam interferograms without contrast modulations. Calculated shearing phases enable further reconstruction of the tested wave front. Experimental works corroborate the principle and capabilities of the proposed approach.

Ultra-thin Plasmonic Chiral Phase Plate

Yuri Gorodetski, Cyriaque Genet, and Thomas Ebbesen

Doc ID: 271979 Received 21 Jul 2016; Accepted 26 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: A thin free standing gold membrane with complex plasmonic structures engraved on its both sides is shown to perform as an ultra-thin phase plate. Specifically, we demonstrate the generation of a far-field vortex beam propagating at a desired angle. The angular momentum of the beam is generated by the groove helicity together with the geometric phase arising from a plasmonic spin-orbit interaction. The radial chirp of the back-side structure is used to modify the emission angle via specific momentum matching condition.

Highly-compact magneto-optical switches for metal-dielectric-metal plasmonic waveguides

Georgios Veronis, Ali Haddadpour, Vahid Foroughi Nezhad, and Zongfu Yu

Doc ID: 271995 Received 20 Jul 2016; Accepted 26 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: We introduce highly-compact magneto-optical switches for metal-dielectric-metal (MDM) plasmonic waveguides. We show that the field profile of the fundamental mode of a MDM waveguide in which the metal is subject to an externally applied static magnetic field is asymmetric. The static magnetic field induced asymmetry, which enhances or reduces the coupling between the waveguide and a side-coupled resonator, and the relatively large induced wave vector modulation are used to design a Fabry-Perot cavity magneto-optical switch, consisting of a MDM waveguide side-coupled to two MDM stub resonators. The on and off states correspond to either the presence or the absence of the externally applied static magnetic field.

Surface sensitive diamond photonic crystals for high performance gas detection

Xavier Checoury, Candice Blin, Zheng Han, Gerard Hugues, Philippe Bergonzo, Philippe Boucaud, Mustafa El-Kurdi, Samuel Saada, and Sébastien Sauvage

Doc ID: 272159 Received 22 Jul 2016; Accepted 25 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: Diamond slotted photonic crystal (PhC) cavities were fabricated and used for gas detection. They exhibit wavelength sensitivity reaching 350 nm per unit change of the refractive index of the gaseous environment of the PhC. With a simple oxidized surface termination, diamond PhCs display an ultra-high sensitivity to surface adsorption of polar molecules. Gaseous concentrations as low as 80 parts per million (ppm) of hexanol vapor in nitrogen are probed and a detection limit in the ppm range is inferred, demonstrating a high interest of such devices for trace sensing.

Ellipsometric characterization of doped Ge0.95Sn0.05 films in the infrared range for plasmonic applications

Lion Augel, Inga Fischer, Florian Hornung, Martin Dressel, Audrey Berrier, Michael Oehme, and Jorg Schulze

Doc ID: 272603 Received 28 Jul 2016; Accepted 25 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: GeSn as a group-IV material opens up new possibilities for realizing photonic device concepts in Si-compatible fabrication processes. Here we present results of the ellipsometric characterization of highly p-type and n-type doped Ge0.95Sn0.05 alloys deposited on Si substrates investigated in the wavelength range from 1 to 16 µm. We discuss the suitability of these films for integrated plasmonic applications in the infrared (IR) region.

Plasmonic Enhanced Two-Photon Absorption in Silicon Photodetectors for Optical Correlators in the Near-Infrared

Alexei Smolyaninov, Yeshaiahu Fainman, Mu-Han Yang, and Lin Pang

Doc ID: 273565 Received 11 Aug 2016; Accepted 25 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: A high density array of plasmonic coaxial nanoantennas is used to enhance the two photon absorption process in a conventional silicon photodetector from a mode locked 76-MHz Ti:sapphire laser over a spectral range from 1340 nm to 1550 nm. This enhanced two photon absorption was used to generate an interferometric autocorrelation trace of a 150 fs laser pulse. Unlike second harmonic generation, this technique doesn’t require phase matching, a bulky crystal, and can be used on a low-cost integrated silicon platform over a wide range of near-IR wavelengths compatible with modern commercial tunable femtosecond sources.

Nanophotonic Modal Dichroism: Mode-Multiplexed Modulators

Alessandro Salandrino, Susobhan Das, Shima Fardad, Rongqing Hui, Junsuk Rho, and Inki Kim

Doc ID: 273917 Received 17 Aug 2016; Accepted 25 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: As the diffraction limit is approached, device miniaturization to integrate more functionality per area becomes more and more challenging. Here we propose a novel strategy to increase the functionality-per-area by exploiting the modal properties of a waveguide system. With such approach the design of a mode-multiplexed nanophotonic modulator relying on the mode-selective absorption of a patterned Indium-Tin-Oxide is proposed. Full-wave simulations of a device operating at the telecom wavelength of 1550nm show that two modes can be independently modulated, while maintaining performances in line with conventional single-mode ITO modulators reported in the recent literature. The proposed design principles can pave the way to a novel class of mode-multiplexed compact photonic devices able to effectively multiply the functionality-per-area in integrated photonic systems.

Simultaneously photonic frequency down-conversion, multi-channel phase shifting and IQ demodulation for wideband microwave signals

aijun Wen, Zhaoyang Tu, Yongsheng Gao, Lin Lin, and Wu Zhang

Doc ID: 268620 Received 28 Jun 2016; Accepted 25 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: A single photonic system that can simultaneously perform frequency down-conversion, multi-channel phase shifting, and in-phase (I) and quadrature (Q) demodulation for microwave signals is proposed and experimentally demonstrated. Using an integrated polarization division multiplexing Mach-Zehnder modulator (PDM-MZM), radio frequency (RF) signals can be frequency down-converted to multi-channel intermediate frequency (IF) signals and the phase of each IF signal can be independently and arbitrarily tuned. Using two quadrature channels, the RF signal can be IQ demodulated. In the experiment, high and flat conversion gains from 8 to 40 GHz and continuously tunable phase shifts over 360-degree range are demonstrated. In addition, vector signals with various modulation formats at 40 GHz are frequency down-converted to baseband and the IQ data are successfully extracted.

Tapered Fiber Nanoprobes: Plasmonic Nanopillars on Tapered Optical Fiber Tips for Large EM Enhancement

Anuj Dhawan and Priten Savaliya

Doc ID: 267653 Received 03 Jun 2016; Accepted 25 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: Employing FDTD simulations, we demonstrate that electromagnetic (EM) field enhancement is substantially greater for tapered optical fibers with plasmonic nanostructures present on their tips as compared with non-tapered optical fibers having those plasmonic nanostructures, or with tapered optical fibers without the plasmonic nanostructures. We also carried out fabrication of plasmonic nanostructures on optical fiber tips.

Sapphire-Fiber-based Distributed High Temperature Sensing System

Bo Liu, Zhihao Yu, Cary Hill, Yujie Cheng, Daniel Homa, Gary Pickrell, and Anbo Wang

Doc ID: 268452 Received 23 Jun 2016; Accepted 24 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: We present, for the first time to our knowledge, a sapphire-fiber-based distributed high temperature sensing system based on Raman distributed sensing technique. High peak power laser pulses at 532 nm were coupled into the sapphire fiber to generate the Raman signal. The returned Raman Stokes and Anti-Stoke signals were measured in the time domain to determine the temperature distribution along the fiber. The sensor was demonstrated from room temperature up to 1200°C in which the averaged standard deviation is about 3.7°C and a spatial resolution of about 14 cm was achieved.

Single step sub-200 fs mid-infrared generation from an optical parametric oscillator synchronously pumped by an erbium fiber laser

Bernd Metzger, Benjamin Pollard, Ingo Rimke, Edlef Büttner, and Markus Raschke

Doc ID: 272826 Received 01 Aug 2016; Accepted 24 Aug 2016; Posted 25 Aug 2016  View: PDF

Abstract: We demonstrate single step generation of mid-infrared femtosecond laser pulses in a AgGaSe₂ optical parametric oscillator that is synchronously pumped by a 100 MHz repetition rate sub-90 fs erbium fiber laser. The tuning range of the idler beam theoretically covers ~ 3.5 to 17 µm only dependent on choice of cavity and mirror design. As an example we experimentally demonstrate idler pulse generation from 4.8 to 6.0 µm optimized for selective vibrational resonant molecular spectroscopy. We find the oscillation threshold as low as 150 mW of pump power. At 300 mW pump and a central wavelength of 5.0 µm we achieve an average infrared power of up to 17.5 mW, with a photon conversion efficiency of ~ 18 %. The pulse duration of ~ 180 fs is determined from a nonlinear cross-correlation with residual pump light. The single step nonlinear conversion leads to an excellent power stability of better than 0.5 % rms over 1 hour.

Simultaneous measurement of mass and rotation of trapped absorbingparticles in air

Ayan Banerjee, Sudipta Bera, Avinash Kumar, Souvik Sil, Tushar Kanti Saha, and Tanumoy Saha

Doc ID: 273325 Received 08 Aug 2016; Accepted 24 Aug 2016; Posted 25 Aug 2016  View: PDF

Abstract: We trap absorbing micro-particles in air by photophoretic forces generatedusing a single loosely focused Gaussian trapping beam.We measure a component of the radial Brownian motion of a trapped particle cluster and determine the power spectral density, mean squared displacement, and normalized position and velocity autocorrelation functions in order to characterize the photophoretic body force in a quantitative fashion for the first time. The trapped particles also undergo spontaneous rotation due to the action of this force. This is evident from the spectral density that displays clear peaks at the rotation and the particles' inertial resonance frequencies. We fit the spectral density to the well-known analytical function derived from the Langevin equation, measure the resonance and rotation frequencies and determine values for particle mass that we verify at different trapping laser powers with reasonable accuracy.

Resolution- and throughput-enhanced spectroscopy using high-throughput computational slit

Farnoud Kazemzadeh and Alexander Wong

Doc ID: 269417 Received 04 Jul 2016; Accepted 24 Aug 2016; Posted 25 Aug 2016  View: PDF

Abstract: There exists a fundamental tradeoff between spectral resolution and the efficiency or throughput for all optical spectrometers. The primary factors affecting the spectral resolution and throughput of an optical spectrometer are the size of the entrance aperture and the optical power of the focusing element. Thus far collective optimization of the above mentioned has proven difficult. Here, we introduce the concept of high-throughput computational slits (HTCS) for improving both the effective spectral resolution and efficiency of a spectrometer. The proposed HTCS approach was experimentally validated using an optical spectrometer configured with a 200 μm entrance aperture, test, and a 50 µm entrance aperture, control, demonstrating improvements in spectral resolution of the spectrum by ~20% over the control spectral resolution and improvements in efficiency of > 2 times the efficiency of the largest entrance aperture used in the study while producing highly accurate spectra.

Temperature-compensated distributed hydrostatic pressure sensor with a thin-diameter polarization-maintaining photonic crystal fiber based on Brillouin dynamic gratings

Lei Teng, Hongying Zhang, Yong Kang Dong, Dengwang Zhou, Taofei Jiang, Wei Gao, Zhiwei Lu, Liang Chen, and Xiaoyi Bao

Doc ID: 270886 Received 19 Jul 2016; Accepted 24 Aug 2016; Posted 26 Aug 2016  View: PDF

Abstract: A temperature-compensated distributed hydrostatic pressure sensor based on Brillouin dynamic gratings (BDGs) is proposed and demonstrated experimentally for the first time, to the best of our knowledge. The principle is to measure the hydrostatic-pressure-induced birefringence changes through exciting and probing the BDGs in a thin-diameter pure silica polarization-maintaining photonic crystal fiber. The temperature cross-talk to the hydrostatic pressure sensing can be compensated through measuring the temperature-induced Brillouin frequency shift changes using Brillouin optical time-domain analysis. A distributed measurement of hydrostatic pressure is demonstrated experimentally using a 4-m sensing fiber, which features a high sensitivity with a measurement accuracy as high as 0.025 MPa at a 20-cm spatial resolution.

Quantitative phase imaging by single-shot Hilbert-Huang phase microscopy

Maciej Trusiak, Krzysztof Patorski, Vicente Mico, and Javier Garcia-Monreal

Doc ID: 272258 Received 26 Jul 2016; Accepted 23 Aug 2016; Posted 24 Aug 2016  View: PDF

Abstract: Quantitative phase imaging (QPI) is a modern optical tool for biomedical phase-sample examination. In this contribution we propose a novel single-shot Hilbert-Huang Transform based algorithm applied to digital holographic microscopy (DHM) for robust, fast and accurate single-shot QPI in on-axis and off-axis configurations. Fringe pattern with possible defects and closed fringes is adaptively filtered and accurately phase demodulated using local fringe direction estimation. Experimental validation of the proposed techniques is presented as DHM study of micro-beads and red blood cells phase-samples. Obtained results compare very favorably with the Fourier approach (off-axis) and temporal phase shifting (on-axis).

Time multiplexing based geometrical aberrations correction

Asaf Ilovitsh, Gilad Rand, Shilo Levavi, and Zeev Zalevsky

Doc ID: 272344 Received 25 Jul 2016; Accepted 23 Aug 2016; Posted 24 Aug 2016  View: PDF

Abstract: The use of the time multiplexing super resolution method for extending the depth of focus of an imaging system was recently presented [Ilovitsh et al., Opt. Lett. 41(1), 183–186 (2016)]. It involved changing the encoding and decoding grating's frequency which determine the optical transfer function duplication positions, and by that obtaining an extended depth of focus. In this Letter we expand this method by showing its applicability for correcting geometrical aberrations of an imaging lens. The proposed method is presented analytically, and validated experimentally for chromatic aberration, spherical aberration, and astigmatism aberration.

2D grating coupler with a low polarization dependent loss of 0.25 dB covering the C-band

Xinliang Zhang, Yu Yu, and jinghui zou

Doc ID: 272446 Received 28 Jul 2016; Accepted 23 Aug 2016; Posted 24 Aug 2016  View: PDF

Abstract: We design and demonstrate a two dimensional grating coupler (2D GC) with a low polarization dependent loss (PDL) based on the silicon-on-insulator (SOI) platform. Using grating cell consisting of 5 cylinders and carefully optimizing the distances between the cylinders, a maximum PDL of 0.25 dB covering the C-band is realized, which is merely 1/5 of a conventional 2D GC fabricated on the same SOI wafer.

Boron carbon nitride based Metal-Insulator-Metal UV detectors for harsh environment applications

Adithya Prakash, Kalpathy Sundaram, and Shraddha Nehate

Doc ID: 268785 Received 22 Jun 2016; Accepted 22 Aug 2016; Posted 23 Aug 2016  View: PDF

Abstract: A metal-insulator-metal (MIM) structures using Boron carbon nitride (BCN) was tested for its UV detection capability. BCN being one of the hardest material and chemically robust, it is expected to be a potential choice for UV detector in extreme and harsh conditions. The BCN thin films were deposited using dual target RF magnetron sputtering process. The optoelectronic performance of the BCN MIM devices were examined through UV photocurrent measurements. A UV photocurrent two orders of magnitude higher with respect to dark current was achieved in the range of -3V to 3V.

Free-space spectro-temporal and spatio-temporal conversion for pulsed light

Eilon Poem, Thomas Hiemstra, Andreas Eckstein, Xianmin Jin, and Ian Walmsley

Doc ID: 269304 Received 29 Jun 2016; Accepted 22 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: We present an apparatus that converts every pulse of a pulsed light source to a pulse train in which the intensities of the different pulses are samples of the spatial or temporal frequency spectrum of the original pulse. In this way, the spectrum of the incident light can be measured by following the temporal response of a single detector. The apparatus is based on multiple round-trips inside a 2f-cavity-like mirror arrangement in which the spectrum is spread on the back focal plane, where after each round-trip a small sectionof the spectrum is allowed to escape. The apparatus is fibre-free, offers easy wavelength range tunability, and a prototype built achieves over 10% average efficiency in the near infra red. We demonstrate the application of the prototype for the efficient measurement of the joint spectrumof a non-degenerate bi-photon source in which one of the photons is in the near infra-red.

Digital holographic metrology based on multi-angle interferometry

jun dong, Chao Jiang, and Shuhai Jia

Doc ID: 269204 Received 24 Jun 2016; Accepted 21 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: We propose a multi-angle interferometry (MAI) method for digital holographic metrology. In an application of three-dimensional (3D) reconstruction, the hologram corresponding to different illumination angle is recorded as the illumination angle with a single wavelength is tilted at regular intervals by an electronically controlled, rotating stage. A Fourier-transform based axial depth scanning algorithm formed by the reconstructed phase is used to obtain the height point by point over the whole field of view. Hence the 3D reconstruction can be obtained effectively even the object has large depth discontinuities suffering from the difficulty of phase-unwrapping. Due to a monochrome source only used, the method is available for object with wavelength-dependent reflectivity and free of chromatic aberration caused by the different wavelengths.

Scanning Mueller polarimetric microscopy

Matthieu DUBREUIL, Aymeric Le Gratiet, Sylvain Rivet, and Yann LE GRAND

Doc ID: 269784 Received 05 Jul 2016; Accepted 21 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: A full Mueller polarimeter was implemented on a commercial laser scanning microscope. The new polarimetric microscope is based on high-speed polarization modulation by spectral coding using a wavelength swept laser as a source. Calibration as well as estimation of the measurement errors of the device are reported. The acquisition of Mueller images at the speed of a scanning microscope is demonstrated for the first time. Mueller images of mineral and biological samples illustrate this new polarimetric microscopy.

Coherence transfer of subhertz-linewidth laser light via an optical fiber noise-compensated by remote users

Yanyi Jiang, Lifei Wu, Chaoqun Ma, Hongfu Yu, Zhiyi Bi, and Long-Sheng Ma

Doc ID: 270315 Received 14 Jul 2016; Accepted 21 Aug 2016; Posted 25 Aug 2016  View: PDF

Abstract: We demonstrate coherence transfer of subhertz-linewidth laser light through a 25-km-long spooled fiber link, where the optical phase noise induced by environmental perturbation via the fiber link is compensated by remote users. When compensating the fiber-induced noise by remote users, the independent time base at the remote site from that at the local site does not destroy the performance of the fiber output light. After compensated, the relative linewidth between the fiber input and output light is 1 mHz, the relative frequency instability is 4 × 10^(−17) at 1 s averaging time and scales down to 2 × 10^(−19) at 800 s averaging time. The system is more suitable for simultaneous transfer of an optical signal to a number of end users within a city.

Supercontinuum generation in ZBLAN glass photonic crystal fiber with six nanobore cores

Xin Jiang, Nicolas Joly, Martin Finger, Fehim Babic, Meng Pang, Rafal Sopalla, Michael Frosz, Samuel Poulain, Marcel Poulain, Vincent Cardin, John Travers, and Philip Russell

Doc ID: 272462 Received 28 Jul 2016; Accepted 21 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: Photonic crystal fibers (PCFs) made from ZBLAN glass are of great interest for generating broadband supercontinua extending into the ultraviolet and mid-infrared regions. Precise sub-micron structuring makes it possible to adjust the modal dispersion over a wide range, making the generation of new frequencies more efficient. Here we report a novel ZBLAN PCF with six cores, each containing a central nanobore of diameter ~330 nm. Each nanobore core supports several guided modes, and the presence of the nanobore significantly modifies the dispersion, strongly influencing the dynamics and extent of supercontinuum generation. Spectral broadening is observed when a single core is pumped in the fundamental and first higher order core-modes with 200 fs-long pulses at a wavelength of 1042 nm. Frequency-resolved optical gating is used to characterize the output pulses when pumping in the lowest order mode. The results are verified by numerical simulations.

Angle-resolved conical emission spectra from filamentation in solid with Airy-pattern and Gaussian laser beam

Cheng Gong, Linqiang Hua, Zixi li, Xiaojun Liu, and Wei Quan

Doc ID: 269972 Received 19 Jul 2016; Accepted 20 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: Filamentation dynamics in fused silica are investigated using Airy-pattern and Gaussian laser beam. The angle-resolved conical emission spectra are measured and compared with the predictions of several models. Our experimental observations are well consistent with the X-waves model in both cases. This indicates that both laser beams are spontaneously evolved into nonlinear X waves and suggests a universal evolution of filaments in fused silica, irrespectively of the initial laser beam profile

Gain-Switching Injection-Locked Dual Optical Frequency Combs: Characterization and Optimization

Borja Jerez, Pedro Martín-Mateos, Estefania Prior, Cristina de Dios, and Pablo Acedo

Doc ID: 270626 Received 14 Jul 2016; Accepted 20 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: In this work, the generation of Dual-Optical Frequency Combs based on Gain-Switching and optical injection locking is experimentally examined. The experimental study reveals that an effective process of optical injection can lead to optimized RF combs regarding span and signal-to-noise ratio. The system also minimizes the overlapping of lines and reduces the number of optical components involved, effectively eliminating the need of any external modulator (electro-optic, acousto-optic). The validation of the system is performed as a dual-comb spectrometer, which has allowed to obtain the absorption and dispersion profile of the molecular transition of H13CN at 1538.5 nm.

Improving the signal-to-noise ratio of the beat note between a frequency comb and a tunable laser using a dynamically tracking optical filter

Hugo Bergeron, Jean-Daniel Deschênes, and Jérôme Genest

Doc ID: 270925 Received 20 Jul 2016; Accepted 19 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: An acousto-optic filter is locked to a tunable continuous wave (CW) laser so that a frequency comb can be dynamically filtered around the wavelength of the CW source. The signal-to-noise ratio (SNR) of the heterodyne beat note between the comb and the CW laser is improved by a factor of up to 19 dB. Furthermore, a SNR of more than 56 dB in 100 kHz is obtained over an 85-nm wavelength span. This technique could enable wideband, agile and cycle-slip-free phase tracking of a beat note accross a full comb spectrum.

Energetic sub-2-cycle laser with 220 W average power

Steffen Hadrich, Marco Kienel, Michael Müller, Arno Klenke, Jan Rothhardt, Robert Klas, Thomas Gottschall, Tino Eidam, András Drozdy, Péter Jójárt, Zoltan Várallyay, Eric Cormier, Karoly Osvay, Andreas Tünnermann, and Jens Limpert

Doc ID: 269598 Received 01 Jul 2016; Accepted 19 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: Few-cycle lasers are essential for many research areas such as attosecond physics that promises to address fundamental questions in science and technology. Therefore, further advancements are connected to significant progress in the underlying laser technology. Here, two-stage nonlinear compression of a 660 W femtosecond fiber laser system is utilized to achieve unprecedented average power levels of energetic ultrashort or even few-cycle laser pulses. In a first compression step 408 W, 320 µJ, 30fs pulses are achieved, which can be further compressed to 216 W, 170 µJ, 6.3 fs pulses in a second compression stage. This is the highest average power few-cycle laser system presented so far. It is expected to significantly advance the fields of high harmonic generation and attosecond science.

Optical polarizer based on the mechanical effect of light

Hao Xiong, Cui Kong, Xiaoxue Yang, and Ying Wu

Doc ID: 262291 Received 28 Jul 2016; Accepted 19 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: Based on the recent experimental progress on chip-scale silicon photonics, a nontrivial polarizing effect arising from the mechanical effect of light is present in an optomechanical crystal, which enables a new nanophotonic polarizer with excellent functionality. Unlike previously reported optical polarizer, the polarizer proposed here can be adjusted rapidly by tuning polarization and intensity of the control field, and may enable on-chip optical control of polarization management with remarkable applications due to the improvement of nano-fabrication techniques.

Stabilizing carrier-envelope offset frequency of a femtosecond laser using heterodyne interferometry

Guanhao Wu, Xiaosheng Zhang, Minghao Hu, and Shilin Xiong

Doc ID: 272497 Received 27 Jul 2016; Accepted 19 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: We propose a time domain fceo stabilization method of a femtosecond laser using heterodyne interferometry. A femtosecond pulse train which is delayed by a spatial delay line interferes with the original pulse train. Phase difference between heterodyne interference signals extracted from different spectral regions is used to stabilize the relative position of the two pulse trains, and then the heterodyne interference phase is used to stabilize the carrier-envelope offset frequency fceo. The experimental results show that the relative Allen deviations of fceo after being stabilized are 1.0×10-⁹ at 0.5s and 4.6×10-¹⁰ at 50s.

Topological surface plasmons in superlattices with changing sign of the average permittivity

Fangwei Ye, Hangying Deng, Xianfeng Chen, and Nicolae Panoiu

Doc ID: 273114 Received 04 Aug 2016; Accepted 19 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: We address the topological properties of one-dimensional plasmonic superlattices composed ofalternating metallic and dielectric layers. We reveal that the Zak phase of such plasmoniclattices is determined by the sign of the spatial average of their permittivity,$\bar{\varepsilon}$, and as such the topology and their associated interfacial (edge) states areextremely robust against structural disorder. Our study shows that the topologically protectedinterfacial modes occurring at the interface between two plasmonic lattices with opposite sign of$\bar{\varepsilon}$ can be viewed as the generalization of the conventional surface plasmonpolaritons existing at metallic-dielectric interfaces.

On the origin of the coherence of sunlight on Earth

Prasanta Panigrahi and Sriram Sundaram

Doc ID: 272974 Received 03 Aug 2016; Accepted 19 Aug 2016; Posted 23 Aug 2016  View: PDF

Abstract: It is shown that the observed far field behavior of sunlight on Earth’s surface, located in the near field region, is due to the small angular width it subtends at the center of the Sun. Investigation of the angular behavior of the cross spectral density function explicitly leads to Bessel like far-zone behavior for small angle, without any restriction on the value of l. Our general analysis for the spherical source, can be easily extended to other geometries.

Spatial Mode Selective Waveguide with Hyperbolic Cladding

Ying Tang, Zheng Xi, Man Xu, Stefan Baumer, Aurèle Adam, and H. Urbach

Doc ID: 268820 Received 29 Jun 2016; Accepted 19 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: Hyperbolic Meta-Materials (HMMs) are anisotropic materials with permittivity tensor that has both positive and negative eigenvalues. Here we report that by using a type II HMM as cladding material, a waveguide which only supports higher order modes can be achieved, while the lower order modes become leaky and are absorbed in the HMM cladding. This counter-intuitive property can lead to novel application in optical communication and photonic integrated circuit. The loss in our HMM-Insulator-HMM (HIH) waveguide is smaller than that of similar guided mode in a Metal-Insulator-Metal (MIM) waveguide.

Propagation of optical coherence lattices in the turbulent atmosphere

Sergey Ponomarenko, Xianglong Liu, Jiayi Yu, and Yangjian Cai

Doc ID: 268904 Received 22 Jun 2016; Accepted 18 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: We explore the propagation of recently introduced optical coherence lattices (OCL) in the turbulent atmosphere. We show that the lattice intensity profile and the spatial degree of coherence will display periodicity reciprocity over long propagation distances even though the lattices are affected by the turbulence. The lattice periodicity reciprocity has been previously conjectured to be advantageous for free-space information transfer and optical communications. We then show how one can increase the distance over which the lattice periodicity reciprocity is preserved in the turbulent atmosphere by engineering input lattice beam parameters. We also show that the OCLs have a lower scintillation index than do Gaussian Schell-model beams.

All-solid-state based laser system as a replacement for Ar+-lasers

Thomas Walther, Tobias Beck, Benjamin Rein, and Fabian Sörensen

Doc ID: 269165 Received 28 Jun 2016; Accepted 18 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: We report on an all-solid-state based laser system at $1028~\rm{nm}$. The light is generated by a diode laser seeded ytterbium fiber amplifier. In two build-up cavities it is frequency doubled and quadrupled to $514~\rm{nm}$ and $257~\rm{nm}$, respectively. At $514~\rm{nm}$ the system delivers up to $5~\rm{W}$ of optical power. In the fourth harmonic up to $180~\rm{mW}$ are available limited by the non-linear crystal. The frequency of the laser is mode-hop free tunable by $16~\rm{GHz}$ in $10~\rm{ms}$ in the UV. Therefore, the system is suited as a low maintenance, efficient, and tunable narrowband replacement for frequency doubled Ar$^+$ laser systems.

80 nJ ultrafast dissipative soliton generation in dumbbell shaped mode-locked fiber laser

Sheng-Ping Chen, He Chen, Zongfu Jiang, and Jing Hou

Doc ID: 269665 Received 14 Jul 2016; Accepted 18 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: A novel all-fiberized dumbbell-shaped mode-locked fiber laser was developed to directly generate 80 nJ dissipative solitons, which can be linearly compressed from 85 ps to 1.2 ps externally with a diffraction grating pair. The pulse peak power reached 42 kW after compression. With the most available pump power, stable dissipative soliton bundles with up to 628 nJ bundle energy were obtained. The corresponding average output power reached 2.2 W. The employment of dual-nonlinear-optical-loop-mirrors and large mode area fiber in the cavity played essential roles in improving structural compactness and producing high energy ultrafast pulses. To the best of our knowledge, it is the most energetic compressible dissipative solitons generated from a strictly all-fiber cavity.

Integrated high responsivity photodetectors based on graphene/glass hybrid waveguide

wang Gencheng, Tingge Dai, zhetao lvy, Yinlei Hao, hui Yu, Yuehai Wang, Yubo Li, Xiaoqing Jiang, and Jianyi Yang

Doc ID: 270198 Received 08 Jul 2016; Accepted 18 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: We propose and fabricate an integrated graphene/glass hybrid photodetector (PD) with high responsivity and broad spectral bandwidth. The glass straight waveguide enables high absorption of the evanescent light of transverse magnetic (TM) mode propagating parallel to the single layer graphene. It is based on the mechanism of light-induced change in conductance. As a result, a responsivity as high as 0.72 A/W at a low bias voltage of -0.1 V for a wide wavelength range from 1510 nm to 1630 nm is experimentally obtained. The proposed graphene/glass hybrid PD could find important applications in graphene based photonic integrated circuits.

Electron Energy Transfer Effect in Au NS/CH3NH3PbI3-xClx Heterostructures via Localized Surface Plasmon Resonance Coupling

Chunfeng Cai, Jizhi Zhai, Gang Bi, and Huizhen Wu

Doc ID: 272500 Received 28 Jul 2016; Accepted 18 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: Localized Surface Plasmon Resonance coupling effects (LSPR) have attracted much attention due to their interesting properties. This paper demonstrated significant PL enhancement in the AuNS/CH3NH3PbI3-xClx heterostructures via LSPR coupling. The observed PL emission enhancement is mainly attributed to the hot electron energy transfer effect related to LSPR coupling. For the energy transfer effect, photo-generated electrons will be directly extracted into Au SPs, rather than relaxed into exciton states. This energy transferring process is much faster than the diffusion and relaxation time of free electrons, and may provide new ideas on the design of high efficiency solar cells and ultrafast response photo detectors.

Time-domain ptychography of over octave spanning laser pulses in the single-cycle regime

Tobias Witting, John Tisch, Jonathan Marangos, Thomas Barillot, Paloma Matia-Hernando, Daniel Walke, and Daniel Greening

Doc ID: 270348 Received 12 Jul 2016; Accepted 18 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: We report the first application of time-domain ptychography for the characterization of few-cycle laser pulses. Our method enables zero additional phase measurements of over octave spanning laser pulses in the single cycle regime. The spectral phase is recovered using a robust ptychography algorithm that requires no input apart from the measured data trace. In addition to numerical tests we validate our new device experimentally by reconstructing the complex electric field of a 1.5 cycle laser pulse with a bandwidth spanning from 490nm to 1060nm. We further check the accuracy of our device by comparing the measured phases of octave spanning chirped pulses to the known dispersion of fused silica glass.

Low drive voltage electro-optic Bragg deflector using periodically poled lithium niobate planar waveguide

Imed Mhaouech, Virginie Coda, Germano Montemezzani, Mathieu Chauvet, and Laurent Guilbert

Doc ID: 268915 Received 28 Jun 2016; Accepted 17 Aug 2016; Posted 17 Aug 2016  View: PDF

Abstract: An electro-optic Bragg light deflector with a low drive voltage is realized in a periodically poled lithium niobate (PPLN) planar waveguide. More than 97% of diffraction efficiency is obtained for the two orthogonal light polarizations with a drive voltage of about 5 V. This is achieved using a 5-µm PPLN thin film confined between two silica layers. The temporal electric drift and the response time of the component are characterized.

Numerical and analytical models to study the laser-driven plasma perturbation in a dielectric gas-filled capillary waveguide

Alessandro Curcio, massimo petrarca, Danilo Giulietti, and Massimo Ferrario

Doc ID: 269964 Received 06 Jul 2016; Accepted 17 Aug 2016; Posted 17 Aug 2016  View: PDF

Abstract: An alternative fast approach to study the propagation of an intense laser pulse through a dielectric capillary waveguide filled with plasma is presented. The numerical model computes the evolution of the capillary mode coupling coefficients and from these parameters the properties of the laser and plasma response are retrieved. Moreover, an analytical description of the process is presented and compared to the numerical model.

Two-photon polymerization setup enables experimental mapping and correction of spherical aberrations for improved macroscopic structure fabrication

Thomas Stichel, Bert Hecht, Sönke Steenhusen, Ruth Houbertz, and Gerhard Sextl

Doc ID: 272629 Received 29 Jul 2016; Accepted 17 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: Two-photon photopolymerization of resins by focused laser light in principle enables the fabrication of structures with details below the diffraction limit. However, the method can be highly susceptible to aberrations, which hinders the fabrication of structures that are larger than e.g. the working distance of the microscope objective. Here, two-photon polymerization is extended to the fabrication of macroscopic structures by making use of medium numerical-aperture microscope objectives. By introducing a substrate holder movable in axial direction it is possible to keep the focusing conditions constant and to fabricate very large structures with heights that are not limited by the working distance of the objective. Moreover, the constant focusing conditions enable us to quantify spherical aberrations by experimental mapping of the optical point-spread function, which manifests itself in the shape of singe photo-polymerized voxels. By monitoring such shapes it is possible to minimize aberrations. Effective aberration control enables us to fabricate large but detailed biomedical scaffolds with interconnected pores, e.g. in the shape of a human stirrup bone.

10-GHz clock time-multiplexed degenerate optical parametric oscillators for a photonic Ising spin network

Hiroki Takesue and Takahiro Inagaki

Doc ID: 272741 Received 01 Aug 2016; Accepted 16 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: A coherent Ising machine based on degenerate optical parametric oscillators (DOPOs) is drawing attention as a way to find a solution to the ground-state-search problem of the Ising model. Here we report the generation of time-multiplexed DOPOs at a 10-GHz clock frequency. We successfully generated >50,000 DOPOs using dual-pump four-wave mixing in a highly nonlinear fiber that formed a 1-km cavity, and observed phase bifurcation of the DOPOs, which suggests that those DOPOs can be used as stable artificial spins. In addition, we demonstrated the generation more than one-million DOPOs by extending the cavity length to 21 km. We also confirmed that the binary numbers obtained from the DOPO phase-difference measurement passed the NIST random number test, which suggests that we can obtain unbiased artificial spins.

Quantum random number generator using a microresonator-based Kerr oscillator

Yoshitomo Okawachi, Mengjie Yu, Kevin Luke, Daniel Carvalho, Michal Lipson, and Alexander Gaeta

Doc ID: 270738 Received 18 Jul 2016; Accepted 16 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: We demonstrate an all-optical quantum random number generator using a dual-pumped degenerate optical parametric oscillator in a silicon nitride microresonator. The frequency-degenerate bi-phase state output is realized using parametric four-wave mixing in the normal group-velocity dispersion regime with two nondegenerate pumps. We achieve a random number generation rate of 2 MHz and verify the randomness of our output using the National Institute of Standards and Technology Statistical Test Suite. The scheme offers potential for a chip-scale random number generator with GHz generation rates and no post processing.

Dual-truncated-cone structure for quasi-distributed multichannel fiber SPR sensor

Yu Zhang, Zhihai Liu, Zongda Zhu, lu liu, yong wei, yushan wang, Yaxun Zhang, Enming Zhao, Jun Yang, Libo Yuan, and Xinghua Yang

Doc ID: 269428 Received 29 Jun 2016; Accepted 16 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: We propose and demonstrate an effective method to adjust the dynamic range of fiber SPR sensor by introducing a multimode fiber sensing probe with a Dual-Truncated-Cone (DTC) structure. When the grind angle of the DTC structure increases, the dynamic range redshifts. Based on this result, we fabricate a quasi-distributed two-channel multimode fiber SPR sensor by cascaded-connecting a DTC sensing probe of 14˚-grind-angle and a traditional Transmitted Multimode Fiber (TMF) sensing probe in the same fiber. The corres-ponding sensitivities of two sensing probes are 34 .08nm/ RIU and 2288.46nm/RIU. By using this quasi-distributed multichannel fiber SPR sensing approach, we may improve the detecting accuracy by extracting, calibrating and compensating for the signals caused by the nonspecific bindings, other physical absorptions, and temperature changes in detecting samples, truly achieving dynamic detection in real-time. The excellences of this multichannel fiber SPR sensor contain that the sensitivity of each sub-channel sensing probe keeps unreduced after they are cascaded-connected in the main-channel fiber; the sensor is based on the multimode fiber, which is inexpensive, accessible and convenient to be universalized in applications.

Molecular fingerprint-region spectroscopy from 5–12 μm using an orientation-patterned gallium phosphide optical parametric oscillator

Luke Maidment, Peter Schunemann, and Derryck Reid

Doc ID: 263907 Received 25 Apr 2016; Accepted 16 Aug 2016; Posted 23 Aug 2016  View: PDF

Abstract: We report a femtosecond optical parametric oscillator (OPO) based on the new semiconductor gain material orientation patterned gallium phosphide (OP-GaP), which enables the production of high-repetition-rate femtosecond pulses spanning 5–12 μm with average powers in the few to tens of milliwatts range. This is the first example of a broadband OPO operating across the molecular fingerprint region, and we demonstrate its potential by conducting broadband Fourier-transform spectroscopy using water vapor and a polystyrene reference standard.

Nano-plasmonic-based structures for DNA sequencing

Vahid Ahmadi, Bashir Fotouhi, and vahid faramarzi

Doc ID: 270797 Received 20 Jul 2016; Accepted 16 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: We propose novel nano-plasmonic-based structures for rapid sequencing of DNA molecules. Optical properties of DNA nu-cleotides have notable differences in the ultraviolet (UV) re-gion of light. Using nanopore, bowtie and bowtie-nanopore compound structures, probable application of the surface plasmon resonance (SPR) in DNA sequencing is investigated by employing discrete dipole approximation method. Effects of different materials like chromium (Cr), aluminum (Al), rhodium (Rh) and graphene (Gr) are studied. We show that for Cr/Al/Gr/Rh, the DNA nucleotide presented to the nanopore shifts SPR spectra /29/5/35 to 48/39/15/68 nm, bowtie 8/2/49/38 to 31/20/79/55 nm and bowtie- nanopore com-pound 25/77/5/16 to 80/80/22/39 nm. The Cr-based struc-tures show excellent sensitivity and selectivity that can be a promising methodology for DNA sequencing.

1.95 µm-pumped OPGaAs-OPO with 10.6 µm idler wavelength

Jochen Wueppen, Sebastian Nyga, Bernd Jungbluth, and Dieter Hoffmann

Doc ID: 267560 Received 06 Jun 2016; Accepted 16 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: We report on an optical parametric oscillator that generates output idler wavelengths around 10.6 µm. On the basis of orientation-patterned Gallium Arsenide (OPGaAs) as nonlinear medium and a 1.95 µm ns pulsed pump laser, a signal-resonant bow-tie resonator was designed in order to maximize the output power at moderate intensities well below the damage threshold of the optical components. With this setup the average idler output power at 50 kHz and 100 ns idler pulse length was more than 800 mW, which corresponds to a pulse energy of 16 µJ. The maximum quantum conversion efficiency of 36.7% is the highest value measured so far for comparable setups to the best of our knowledge.

Experimental demonstration of a light beam with superior aberration resilience

Bosanta Boruah, Mohd Gaffar, and RANJAN KALITA

Doc ID: 269759 Received 04 Jul 2016; Accepted 16 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: In this paper we present the experimental results of a focused light beam that exhibits superior resilience to various common monochromatic aberrations. The light beam, obtained by applying a helical phase mask on an azimuthally polarized beam, has an Airy pattern like circularly symmetric focal spot. Our results show that the beam in the presence of aberrations has better performance in terms of Strehl ratio and effect on the radius of the encircled energy relative to a normal linearly polarized or circularly polarized beam. Our experimental results agree well with the corresponding theoretical results.

Cylindrical Talbot effect for ultra-compact multimode interference couplers

parya samadian and Trevor Hall

Doc ID: 270332 Received 13 Jul 2016; Accepted 15 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: Tapered multimode interference (MMI) couplers have been broadly studied for applications in integrated photonic circuits due to their smaller footprint than conventional MMIs. The operation of an MMI is fundamentally related to the Talbot effect. In this paper Talbot effect is analyzed in cylindrical coordinates, rather than a conventional Cartesian coordinates is analyzed. A cylindrical geometry is found to result in a significant reduction of Talbot distance and hence more compact MMIs. Simulation results are compared to theoretical predictions and results in the literature to confirm the accuracy of the method.

Green high-power narrow-linewidth tunable external-cavity GaN diode laser at 515 nm

Mingjun Chi, Ole Jensen, and Paul Petersen

Doc ID: 270692 Received 15 Jul 2016; Accepted 15 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2,1 nm is obtained. This constitutes the highest output power from a tunable green diode laser system.

Localized waves supported by the rotating waveguide array

Fangwei Ye, Yaroslav Kartashov, Zhang Xiao, Xianfeng Chen, and Victor Vysloukh

Doc ID: 270790 Received 18 Jul 2016; Accepted 15 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: We show that truncated rotating square waveguide arrays support new types of localized modes that exist even in the linear case, in complete contrast to localized excitations in nonrotating arrays requiring nonlinearity for their existence and forming above the energy flow threshold. These new modes appear either around array center, since rotation leads to the emergence of the effective attractive potential with a minimum at the rotation axis, or in the array corners, in which case localization occurs due to competition between centrifugal force (in terms of quasi-particle analogy) and total internal reflection at the interface of truncated array. The degree of lo-calization of central and corner modes mediated by rotation increases with rotation frequency. Stable rotating soliton families bifurcating from linear modes are analyzed in both focusing and defocusing media. Such modes can form in arrays of different geometries and for different array terminations.

Quantum scattering theory of Fock states in three-dimensional spaces

jingfeng liu, Zongfu Yu, and Ming Zhou

Doc ID: 267662 Received 03 Jun 2016; Accepted 15 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: A quantum scattering theory is developed for Fock states scattered by two-level systems in three-dimensional free space. It is built upon the one-dimensional scattering theory developed in waveguide quantum electrodynamics. The theory fully quantizes the incident light as Fock states and uses a non-perturbative method to calculate the scattering matrix.

Single-sideband W-band photonic vector mm-wave signal generation by one single I/Q modulator

Xinying Li, Yuming Xu, and Jianjun Yu

Doc ID: 268817 Received 21 Jun 2016; Accepted 15 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: We propose one new scheme to generate single-sideband (SSB) photonic vector millimeter-wave (mm-wave) signal adopting asymmetrical SSB modulation enabled by one single in-phase/quadrature (I/Q) modulator. The driving signal for the I/Q modulator is generated by software-based digital signal processing (DSP) instead of a complicated transmitter electrical circuit, which significantly simplifies the system architecture and increases the system stability. One vector-modulated optical sideband and one unmodulated optical sideband, with different sideband frequencies, located at two sides of a significantly suppressed central optical carrier, are generated by the I/Q modulator and used for heterodyne beating to generate the electrical vector mm-wave signal. The two optical sidebands are robust to fiber dispersion and can be transmitted over relatively long-haul fiber. We experimentally demonstrate the generation and transmission of 4-Gbaud 80-GHz quadrature-phase-shift-keying-modulated (QPSK-modulated) SSB vector mm-wave signal over 80-km single-mode fiber-28 (SMF-28) without optical dispersion compensation.

A Guideline of Choosing Optical Delay Time to Optimize the Performance of Interferometry-based In-band OSNR Monitor

Zhuili Huang, Jifang Qiu, Sheng Wang, Xue Ji, tian ye, Deming Kong, Miao Yu, and Jian Wu

Doc ID: 269047 Received 24 Jun 2016; Accepted 15 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: We propose and experimentally demonstrate a guideline of choosing optical delay time in an interferometry-based optical signal-to-noise ratio (OSNR) monitor to achieve optimal monitoring performance by calculating normalized autocorrelation function of channel noise. According to the position of the first zero point of the calculated autocorrelation function, the delay time is determined, consequently OSNR monitoring range up to 29 dB (within error ≤±0.5 dB) is achieved for 112 Gb/s PM-QPSK signal with channel filter bandwidth of 100 GHz. Experimental results also show that the guideline is applicable to channel filters with different bandwidths and shapes. In simulation, the guideline is proven to be valid in OSNR monitoring for 28-Gbaud PM-16QAM signal and 50-Gbaud PM-QPSK signal.

Mid-infrared multimode fiber coupled quantum cascade laser for off-beam quartz-enhanced photoacoustic detection

Wei Ren, Zhili Li, and Chao Shi

Doc ID: 272040 Received 26 Jul 2016; Accepted 15 Aug 2016; Posted 16 Aug 2016  View: PDF

Abstract: A mid-infrared quartz-enhanced photoacoustic sensor was developed using a multimode fiber (MMF) coupled quantum cascade laser (QCL) and demonstrated for sensitive nitric oxide (NO) detection at the wavelength near 5.26 μm. The QCL radiation was readily coupled into a solid-core InF₃ MMF (100-μm core) with 97% coupling efficiency using an aspheric lens. Despite of the 25.5% transmission loss for the 1-m long MMF, the Gaussian-beam like fiber output of 5.72° divergence was almost completely focused through the micro-resonator tube (length: 8.0 mm, ID: 600 μm) designed for off-beam quartz-enhanced photoacoustic spectroscopy. The sensor exploiting the R6.5 (²Π₁/₂) doublet of NO at 1900.08 cm-¹ demonstrated a detection sensitivity of 24 ppbv at an averaging time of 130 sec. The sensor was found insensitive to the fiber bending noise for a bending radius >5 cm.

Reduction of residual excess noise in Class-A lasers using two-photon absorption

Kevin Audo, Abdelkrim El Amili, Ghaya Baili, Daniel Dolfi, and Mehdi Alouini

Doc ID: 268153 Received 13 Jun 2016; Accepted 15 Aug 2016; Posted 17 Aug 2016  View: PDF

Abstract: We demonstrate experimentally a significant reduction of the remaining excess intensity noise in a class-A semi-conductor laser. This is obtained by inserting, into the laser cavity, a buffer reservoir mechanism based on two-photon absorption in GaAs. The excess noise peak at the laser free spectral range, induced by the beating between the lasing mode and amplified spontaneous emission in the adjacent non-oscillating modes, is reduced by 20 dB while preserving the class-A dynamical behavior of the laser cavity.

Precise phase determination with the built-in spectral interferometry in two-dimensional electronic spectroscopy

Yizhu Zhang, T.-M. YAN, and Y. H. JIANG

Doc ID: 270172 Received 14 Jul 2016; Accepted 15 Aug 2016; Posted 15 Aug 2016  View: PDF

Abstract: A new method determining the precise phase of pulse sequences in two-dimensional electronic spectroscopy (2DES) is proposed merely using the already built-in spectral interferometry (SI). The approach is easily implemented without the supplementary instrumental construction, only at expense of few additional scanning and data-fitting process. This method effectively avoids the phase ambiguities of the beam propagation in samples, calibrates the absolute phase at the exact interaction region, and improves the phasing procedure in 2DES in a more convenient way.

Spectrally encoded common-path fiber-optic based parallel optical coherence tomography

Kye-Sung Lee, Hwan Hur, Ha-Young Sung, I Jong Kim, and Geon-Hee Kim

Doc ID: 270319 Received 12 Jul 2016; Accepted 15 Aug 2016; Posted 19 Aug 2016  View: PDF

Abstract: We demonstrate a fiber-optic based parallel OCT using spectrally encoded extended illumination with a common-path hand held probe where the flexibility and robustness of the system are significantly improved, which is critical in the clinical environment. To the best of our knowledge, we first present the parallel OCT based on fiber optics including a fiber coupler. We also investigated the effect of the phase stability of the fiber based interferometry on the parallel OCT system comparing the common-path OCT with two-arm OCT. Using the home-designed common-path hand held probe based on Mirau interferometer, the phase stability was 32 times better than that of the two-arm OCT. The axial resolution of the common-path OCT was measured 5.1 ± 0.3 μm. To demonstrate the in vivo imaging performance of the fiber-optic based parallel OCT, Human skin was imaged.

A compact cavity-dumped Q-switched Er:YAG laser

David Ottaway, Lachlan Harris, Myles Clark, and Peter Veitch

Doc ID: 267739 Received 13 Jun 2016; Accepted 15 Aug 2016; Posted 25 Aug 2016  View: PDF

Abstract: We report a compact cavity-dumped Q-switched Er:YAG laser that produces pulses with 4.5 ns full-width-half-maximum duration and 10 mJ energy. The resulting 2 MW peak power is the highest reported to date from a 1645 nm Er:YAG laser

Simulation of oxygen saturation measurement in a single blood vein

Dror Fixler, Hamootal Duadi, and Meir Nitzan

Doc ID: 270558 Received 14 Jul 2016; Accepted 15 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: The value of oxygen saturation in venous blood, SvO2, has important clinical significance since it is related to the tissue oxygen utilization, which is related to the blood flow to the tissue and to its metabolism rate. However existing pulse oximetry techniques are not suitable for blood in veins. In the current study we examine the feasibility of difference oximetry to assess SvO2 by using two near infra-red wavelengths and collecting the backscattered light from two photo-detectors located in different distance from the light-source.

Electro-optic dual-comb interferometry over40-nm bandwidth

Vicente Durán, Peter Andrekson, and Victor Torres-Company

Doc ID: 269671 Received 04 Jul 2016; Accepted 14 Aug 2016; Posted 15 Aug 2016  View: PDF

Abstract: Dual-comb interferometry is a measurement technique that uses two laser frequency combs to retrieve complex spectra in a line-by-line basis. This technique can be implemented with electro-optic frequency combs, offering intrinsic mutual coherence, high acquisition speed and flexible repetition-rate operation. A challenge with the operation of this kind of frequency comb in dual-comb interferometry is its limited optical bandwidth. Here, we use coherent spectral broadening and demonstrate electro-optic dual-comb interferometry over the entire telecommunications C band (200 lines covering ~ 40 nm, measured within 10 microseconds at 100 signal-to-noise ratio per spectral line). These results offer new prospects for electro-optic dual-comb interferometry as a suitable technology for high-speed broadband metrology, for example in optical coherence tomography or coherent Raman microscopy.

Ultra-low loss visible surface plasmon based waveguides formed in indium-tin-oxide coated Fe-doped LiNbO3 slabs

Jingwen Zhang, Hua Zhao, Tingyu Xue, and Liang Li

Doc ID: 269804 Received 12 Jul 2016; Accepted 14 Aug 2016; Posted 15 Aug 2016  View: PDF

Abstract: Visible reconfigurable waveguides were evidenced in a composite slab formed with an indium-tin-oxide (ITO) coated iron doped lithium noibate (LN). The surface plasmon polaritions excited were believed behind the observed light guiding along the ITO/LN interfaces, which is inherent with super-low loss for its sum-nm modified layer. The forward near surface normal scattering and accompanying reduction of the specular reflectivity in the front ITO/LN interface consistent with the SPP excitation.

Optical manipulation using optimal annular vortices

Ulises Ruiz, Victor Arrizon, Rafael Páez, and Ruben Ramos-Garcia

Doc ID: 270226 Received 14 Jul 2016; Accepted 13 Aug 2016; Posted 15 Aug 2016  View: PDF

Abstract: We discuss a simple method to generate a configurable annular vortex beam (AVB) with the maximum possible peak intensity, employing a phase hologram whose transmittance is the phase of a Bessel beam. Due to its maximum intensity, the AVB provides the optimal density of orbital angular moment (OAM). Another attribute of the generated AVB is the relatively high invariance of the intensity profile when the topological charge is changed. We demonstrate the advantages and flexibility of these AVBs for optical trapping applications.

Heterogeneous integration of III-V VCSEL light source for optical fibre sensing

Hongqiang Li, Xiangdong Ma, Danyang Yuan, zanyun zhang, Enbang Li, and Chunxiao Tang

Doc ID: 270499 Received 15 Jul 2016; Accepted 13 Aug 2016; Posted 15 Aug 2016  View: PDF

Abstract: We propose a fiber Bragg grating (FBG) sensor interrogation system utilizing a III-V vertical cavity surface emitting laser (VCSEL) as the on-chip light source. Binary blazed grating (BBG) for coupling between III-V VCSEL and silicon-on-insulator (SOI) waveguides is demonstrated for interrogation of the FBG sensor. The footprint size of the BBG is only 5.62 µm × 5.3 µm, and each BBG coupler period has two subperiods. The diameter of VCSEL's emitting window is 5 µm, which is slightly smaller than that of the BBG coupler, to be well-matched with the proposed structure. Results show that the coupling efficiency from vertical cavities of the III-V VCSEL to the in-plane waveguides reached as high as 32.6% when coupling the 1550.65 nm light. The heterogeneous integration of the III-V VCSEL and SOI waveguides by BBG play a fundamental role to induce a great breakthrough to the miniaturization of the on-chip light source for optical fiber sensing.

A compact and cost-effective temperature insensitive bio-sensor based on long period fiber gratings for accurate detection of E. coli bacteria in water

Saurabh Tripathi, KRISHNENDU DANDAPAT, Wojtek Bock, Predrag Mikulic, and Yasser Chiniforooshan

Doc ID: 268231 Received 14 Jun 2016; Accepted 13 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: We propose and demonstrate a novel temperature insensitive bio-sensor for accurate and quantitative detection of E. coli bacteria in water. Surface sensitivity is maximized by operating the long-period-fiber-grating (LPFG) closest to its turn-around wavelength and the temperature insensitivity is achieved by selectively exciting a pair of cladding modes with opposite dispersion characteristics. Our sensor shows a nominal temperature sensitivity of ∼1.25 pm/°C, which can be further reduced by properly adjusting the LPFG lengths, while maintaining high refractive index sensitivity of 1929 nm/RIU. The overall length of the sensor is ∼3.6 cm making it ideally suitable for bio-sensing applications. As an example we also show the sensors capability of reliable, quantitative detection of E. coli bacteria in water over a temperature fluctuations of room temperature to 40 ºC.

Germanium-on-silicon mid-infrared grating couplers with low-reflectivity inverse taper excitation

Carlos Alonso Ramos, Milos Nedeljkovic, Daniel Benedikovic, Jordi Soler Penades, Callum Littlejohns, Diego Pérez-Galacho, Laurent Vivien, Pavel Cheben, and Goran Mashanovich

Doc ID: 270520 Received 14 Jul 2016; Accepted 12 Aug 2016; Posted 22 Aug 2016  View: PDF

Abstract: A broad transparency range of its constituent materials and compatibility with standard fabrication processes make germanium-on-silicon (Ge-on-Si) an excellent platform for the realization of mid-infrared photoniccircuits. However, the comparatively large Ge waveguide thickness and its moderate refractive index contrast with the Si substrate hinder the implementation of efficient fiber-chip grating couplers. We report, for the first time, a single-etch Ge-on-Si grating coupler with an inversely tapered access stage, operating at 3.8 μm wavelength. Optimized grating excitation yields a coupling efficiency of -11 dB (7.9%), the highest value reported for a mid-infrared Ge-on-Si grating coupler, with reflectivity below -15 dB (3.2%). The large periodicity of our higher-order grating design substantially relaxesfabrication constraints. We also demonstrate that a focusing geometry allows a ten-fold reduction in inverse taper length, from 500 μm to 50 μm.

Phase change material based ultrafast tunable nanoantennas

Rasoul Alaee, Mohammad Albooyeh, Sergei Tretyakov, and Carsten Rockstuhl

Doc ID: 269595 Received 01 Jul 2016; Accepted 12 Aug 2016; Posted 12 Aug 2016  View: PDF

Abstract: We suggest a novel switchable plasmonic dipole nanoantenna operating at mid-infrared frequencies that exploits phase change materials. We show that the induced dipole moments of a nanoantenna, where a Ge₃Sb₂Te₆ (GST) nanopatch acts as a spacer between two coupled metallic nanopatches, can be controlled in a disruptive sense. By switching GST between its crystalline and amorphous phase, the nanoantenna can exhibit either an electric or a balanced magneto-electric dipole-like radiation. While the former radiation pattern is omnidirectional, the latter is directive. Based on this property, exciting switching devices can be perceived such as, e.g., a metasurface whose functionality can be switched between an absorber and a reflector. The switching between stable amorphous and crystalline phases occurs on timescales of nanoseconds and can be achieved by external laser pulses.

Surface, waveguide and substrate collection of Raman emission in waveguide-enhanced Raman spectroscopy

Zilong Wang, Michalis Zervas, philip bartlett, and James Wilkinson

Doc ID: 270113 Received 15 Jul 2016; Accepted 12 Aug 2016; Posted 12 Aug 2016  View: PDF

Abstract: We demonstrate Raman spectroscopy on a high index thin film tantalum pentoxide waveguide and compare collection of Raman emission from the waveguide end with that from the waveguide surface. Toluene was used as a convenient model analyte, and 40-fold greater signal was collected from the waveguide end. Simulations of angular and spatial Raman emission distributions showed good agreement with experiments, with the enhancement resulting from efficient collection of power from dipoles near the surface into the high-index waveguide film and substrate, combined with long interaction length. The waveguide employed was optimized at the excitation wavelength but not at emission wavelengths, and full optimization is expected to lead to enhancements comparable to SERS in robust low-cost metal and nanostructure-free chips.

Method for remotely measuring the spin damping time of mesospheric sodium

Hongyan Wang, Lihang Li, Weihong Hua, Yu Ning, and Xiaojun Xu

Doc ID: 270130 Received 13 Jul 2016; Accepted 12 Aug 2016; Posted 12 Aug 2016  View: PDF

Abstract: By using the return flux enhancement factor due to repumping, the spin damping time of mesospheric sodium can be estimated. Because the absolute return photon number does not need to be measured, this method is independent of sodium abundance. An example of how to find the spin damping time using this method is given. As a result, it is shown that this method is sensitive and has the potential to improve the precision of the spin damping time estimations of mesospheric sodium. Finally, the impact of the geomagnetic field on this method is analyzed.

The radiation pressure assist maneuver

Grover Swartzlander, Alexandra Artusio-Glimpse, and Jacob Wirth

Doc ID: 269182 Received 30 Jun 2016; Accepted 11 Aug 2016; Posted 12 Aug 2016  View: PDF

Abstract: We describe an energy transfer process whereby a moving particle loses (or gains) kinetic energy upon interacting with the moving optical potential of a swept beam of light. This optomechanical approach for slowing or speeding a particle is akin to a gravitational assist maneuver for interplanetary satellite propulsion. Special consideration is given to the stopping of a particle. For analytical convenience we examine the Rayleigh scattering regime, providing examples at both small and large scattering angles. A general stopping condition is expressed in terms of the particle scattering angle (measured in the reference frame of the moving beam) and a so-called approach angle of the particle. We find that a 5% uncertainty in the initial particle speed and position has negligible effect on the slowing / speeding ability when the beam size is much larger than the particle.

Direct-Detection Mode-Division Multiplexing in Modal Basis Using Phase Retrieval

Sercan Arik and Joseph Kahn

Doc ID: 265153 Received 13 May 2016; Accepted 10 Aug 2016; Posted 10 Aug 2016  View: PDF

Abstract: Mode-division multiplexing (MDM) can increase the capacity of direct-detection (DD) short-reach systems in proportion to the number of modes employed. MDM requires compensation of modal crosstalk at a transmitter or receiver by multi-input multi-output (MIMO) signal processing. We show that the channel estimation required for MIMO processing in a basis of modes can be expressed as a phase retrieval problem. We propose three techniques for estimation: sparse training sequences, convex optimization (CO) and alternating minimization. We demonstrate the superior performance of the CO technique.

Off-axis QEPAS using a pulsed nanosecond Mid-Infrared Optical Parametric Oscillator

Mikael Lassen, Laurent Lamard, Paul Feng, Andre Peremans, and Jan Petersen

Doc ID: 266888 Received 25 May 2016; Accepted 09 Aug 2016; Posted 10 Aug 2016  View: PDF

Abstract: A trace gas sensor, based on quartz-enhanced photoacoustic spectroscopy (QEPAS), consisting of two acoustically coupled micro-resonators (mR) with an off-axis 20 kHz quartz tuning fork (QTF) is demonstrated. The complete acoustically coupled mR system is optimized based on finite element simulations and experimentally verified. The QEPAS sensor is pumped resonantly by a nanosecond pulsed single-mode mid-infrared optical parametric oscillator (MIR OPO). The sensor is used for spectroscopic measurements on methane in the 3.1 μm to 3.5 μm wavelength region with a resolution bandwidth of 1 cm^-1 and a detection limit of 0.8 ppm. An Allan deviation analysis shows that the detection limit at optimum integration time for the QEPAS sensor is 32ppbv@190s and that the background noise is solely due to the thermal noise of the QTF.

Quantitative photoacoustic tomography by stochastic search: direct recovery of the optical absorption field

R. Vasu, Mamatha Venugopal, Peter van Es, Srirang Manohar, and Debasish Roy

Doc ID: 261637 Received 24 Mar 2016; Accepted 09 Aug 2016; Posted 10 Aug 2016  View: PDF

Abstract: We present, perhaps for the first time, a stochastic search algorithm in quantitative photoacoustic tomography (QPAT) for a one-step recovery of the optical absorption map from time-resolved photoacoustic signals. Such a direct recovery is free of the numerical inaccuracies inherent in conventional two-step approaches that depend on an accurate estimation of the absorbed energy distribution. The absorption profile parameterized as a vector stochastic process is additively updated over time recursions so as to drive the measurement-prediction misfit to a zero-mean white noise. The derivative-free additive update is a welcome departure from the conventional gradient-based methods requiring evaluation of Jacobians at every recursion. The quantitative accuracy of the recovered absorption map from both numerical and experimental data is good with an overall error of less than 10%.

56 Gb/s Multi-band CAP for Data Center Interconnects up to 80 km SMF

Jinlong Wei, Nicklas Eiselt, Christian Sánchez, Helmut Griesser, and Ruoyang Du

Doc ID: 269299 Received 29 Jun 2016; Accepted 08 Aug 2016; Posted 08 Aug 2016  View: PDF

Abstract: We present the first experimental demonstration of a 56 Gb/s multi-band CAP signal transmission over 80-km SMF link with zero overhead pre-FEC signal recovery and enhanced timing jitter tolerance for optical data center interconnects.

Structured Illumination Assisted Microdeflectometry with Optical Depth Scanning Capability

Hong Hua and SHENG-HUEI LU

Doc ID: 270220 Received 11 Jul 2016; Accepted 05 Aug 2016; Posted 08 Aug 2016  View: PDF

Abstract: Microdeflectometry is a powerful noncontact tool for measuring nanometer defects on a freeform surface. However, it requires a time-consuming process to take measurements at different depths for an extended depth of field and lacks surface information for integrating measured gradient data to height. We propose an optical depth scanning technique to speed up the measurement process and introduce structured illumination technique to efficiently determine the focused data among 3D observation and provide surface orientations for reconstructing an unknown surface shape. We demonstrated 3D measurements with an equivalent surface height sensitivity of 7.21 nm and an EDOF of at least 250 μm, which is 15 times of the diffraction limited depth range.

Inverse polarizing effect of elliptical-polarization recorded hologram at large cross angle

Guoguo Kang, Yiying Zhang, Jinliang Zang, Que Wang, Ying Liu, Xiaodi Tan, Tsutomu Shimura, and Kazuo Kuroda

Doc ID: 270311 Received 12 Jul 2016; Accepted 05 Aug 2016; Posted 10 Aug 2016  View: PDF

Abstract: we report on the inverse polarizing effect (IPE) of elliptical-polarization recorded hologram at a large recording angle. IPE is a polarizing phenomenon that the reconstructed signal switches major and minor axis and keeps the original polarization direction compared to that of the signal wave. In reviewing the case of linear-polarization and circular-polarization recorded hologram, we found that IPE is an unique phenomenon for elliptical polarization. IPE was observed at the cross angle of 38°experimentally, and was theoretically explained using the tensor theory.

Thulium-based fiber CPA system with 2 GW of peak power

Christian Gaida, Martin Gebhardt, Fabian Stutzki, Cesar Jauregui, Jens Limpert, and Andreas Tünnermann

Doc ID: 269164 Received 24 Jun 2016; Accepted 05 Aug 2016; Posted 12 Aug 2016  View: PDF

Abstract: Thulium-doped fibers with ultra large mode-field areas offer new opportunities for the power scaling of mid-IR ultrashort-pulse laser sources. Here, we present a laser system delivering a pulse-peak power of 2 GW and a nearly transform-limited pulse duration of 200 fs in combination with 28.7 W of average power. This performance level has been achieved by optimizing the pulse shape, by reducing the overlap with atmospheric absorption lines and by incorporating a climate chamber to reduce the humidity of the atmospheric environment.

Near-field diffraction of chirped gratings

Luis Miguel Sanchez-Brea, Francisco Jose Torcal-Milla, and Tomas Morlanes

Doc ID: 269534 Received 07 Jul 2016; Accepted 05 Aug 2016; Posted 12 Aug 2016  View: PDF

Abstract: In this work we analyze the near-field diffraction pattern produced by chirped gratings. Besides, an intuitive analytical interpretation of the generated diffraction orders is proposed. Several interesting properties of the near field diffraction pattern can be determined, such as the period of the fringes (pseudo-self-images) and its visibility. Diffraction orders present different widths and also, some of them present focusing properties. The width, location and depth of focus of the converging diffraction orders is also determined. The analytical expressions are compared to numerical and experimental results, showing a high agreement.

triSPIM: light sheet microscopy with isotropic super-resolution

James Manton and Eric Rees

Doc ID: 268634 Received 23 Jun 2016; Accepted 04 Aug 2016; Posted 04 Aug 2016  View: PDF

Abstract: We propose a three-objective light sheet microscopy geometry which, through a combination of skewed lattice light sheet excitation through two objectives and the computational fusion of images taken from two separate lens pairings, would allow for isotropic super-resolution in mesoscopic samples. We also show that simultaneous coherent excitation through two excitation objectives could further substantially increase resolution. Simulations demonstrate that our design could achieve a resolution of 120 nanometres for EGFP imaging while minimising photodamage.

THz radiation from bismuth surface induced by femtosecond laser pulses

Daniil Fadeev, Igor Ilyakov, Boris Shishkin, Ivan Oladyshkin, Valery Chernov, Andrey Okhapkin, Pavel Yunin, Vyacheslav Mironov, and Rinat Akhmedzhanov

Doc ID: 270128 Received 07 Jul 2016; Accepted 04 Aug 2016; Posted 04 Aug 2016  View: PDF

Abstract: We report on the first experimental observation of terahertz (THz) wave generation from bismuth mono- and polycrystalline samples irradiated by femtosecond laser pulses. Dependencies of the THz signal on the crystal orientation, on the optical pulse energy, incidence angle and polarization are presented and discussed together with features of the samples’ surfaces. The optical-to-THz conversion efficiency was up to two orders higher than for metal at moderate fluence of ~1mJ/cm2. We also found nonlinear effects not previously observed using other metal and semiconductor materials: a) asymmetry of THz response with respect to half-turn of a sample around its normal, b) THz polarization control by orientation of a samples’ surface, c) strong enhancement of optical-to-THz conversion after structuring of a sample with optically large-scale parallel strips pattern.

Complete snapshot Stokes polarimeter based on a single biaxial crystal

Irene Estévez, Víctor Sopo, Angel Lizana, Alex Turpin, and Juan Campos

Doc ID: 267274 Received 27 May 2016; Accepted 28 Jul 2016; Posted 28 Jul 2016  View: PDF

Abstract: We propose a new snapshot complete Stokes polarimeter based on a single biaxial crystal. The proposed optical scheme presents different strengths (snapshot, complete polarimetric measurements, large data redundancy and high sensitivity) in a simple and compact optical arrangement. The polarimeter is experimentally implemented and analyzed in terms of accuracy and repeatability.

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