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Accepted papers to appear in an upcoming issue

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Fiber Loop Ring-down Cavity Integrated U-bent Single-Mode-Fiber for Magnetic Field Sensing

Qun Han, Yaofei Chen, Wenchuan Yan, Lin Yu, and T. Liu

Doc ID: 273988 Received 24 Aug 2016; Accepted 20 Oct 2016; Posted 21 Oct 2016  View: PDF

Abstract: A novel magnetic field sensing system based on the fiber loop ring-down technique is proposed in this paper. In the fiber loop, a U-bent single-mode-fiber structure coated with magnetic fluid (MF) serves as the sensing head, and an erbium-doped fiber amplifier (EDFA) is introduced to compensate the intrinsic loss of the cavity. The ring-down time of the system varies with the change of applied magnetic field due to the tunable absorption coefficient and refractive index of the MF. Therefore, the measurement for magnetic field can be realized by monitoring the ring-down time. The experimental results show that the performance of the system is extremely dependent on the interrogation wavelength because both the gain of the EDFA and the loss of the sensing head are wavelength-dependent. We found that at the optimal wavelength the ratio of the gain to loss got its maximum. The sensing system was experimentally demonstrated and a sensitivity of -0.5951μs/Oe was achieved.

Photonic Band Gap Structure and Long-Range Periodicity of Cumulative Fibonacci Lattice

Hui Xiong and Chenhui Yu

Doc ID: 275105 Received 02 Sep 2016; Accepted 11 Oct 2016; Posted 13 Oct 2016  View: PDF

Abstract: In this work, we study the photonic band of cumulative Fibonacci lattices, of which the structure is composed of all generated units in a Fibonacci sequence. The results are compared with DBR structures of the same layers number. Photonic band gaps are found at two characteristic frequencies, symmetrically separated from the central band gap in the DBR counterpart. Field amplitude and phase distribution in the Fibonacci lattice indicates an interferential origin of the band gaps. Fourier transform on the refractive index profile is carried, and the result implies a determined long-range periodicity that agrees well with the photonic band structure.

Scalar-Matrix-Structured Ghost Imaging

Fengli Gao, chao yang, Chenglong Wang, Jian Guan, chi zhang, Xu Guo, and Wenlin Gong

Doc ID: 272680 Received 29 Jul 2016; Accepted 11 Oct 2016; Posted 13 Oct 2016  View: PDF

Abstract: We report a reconstruction method for ghost imaging, Scalar-Matrix-Structured Ghost Imaging (SMGI). In this method, characteristic matrix constructed by the speckle patterns is amended to approach a scalar matrix to weaken the noise caused by the off-diagonal part of the characteristic matrix, so that the Peak Signal Noise Ratio (PSNR) of the object reconstruction can be further improved. Compared to Differential Ghost Imaging (DGI), SMGI performs better on enhancing PSNR with the same measurement times. Meanwhile, the reconstructions keep good with the existence of two-arm longitudinal difference, which indicates promising application prospects. To our knowledge, this is the first time the ghost imaging object reconstruction is investigated from the perspective of scalar matrix.

Understanding localized surface plasmon resonance with propagative surface plasmon polaritons in optical nanogap antennas

Haitao Liu, Hongwei Jia, Fan Yang, and Ying Zhong

Doc ID: 273965 Received 17 Aug 2016; Accepted 09 Oct 2016; Posted 13 Oct 2016  View: PDF

Abstract: Plasmonic nanogap antenna is an efficient radiating or receiving optical device. The resonance behavior of optical antennas is commonly attributed to the excitation of a localized surface plasmon resonance (LSPR), which can be theoretically identified as the quasi normal mode (QNM). To clarify the physical origin of the LSPR, we build up an analytical model of the LSPR by considering a multiple scattering process of propagative surface plasmon polaritons (SPPs) on the antenna arms. The model can comprehensively reproduce the complex eigen-frequency and the field distribution of QNMs of the antenna, unveiling that the LSPR arises from a Fabry-Perot resonance of SPPs. By further applying the complex pole expansion theorem of meromorphic functions, the field of the antenna under illumination by a nearby dipole emitter can be analytically expanded with QNMs, which well predicts the frequency response of the enhancement factor of radiation. The present model bridges the gap between the concepts of the LSPR and the propagative SPP and integrates the advantages of the Fabry-Perot and QNM formalisms of nanogap antennas.

Power-scaled dissipative soliton using double cladding-pumped Yb-doped all-fiber amplifier

hussein kotb, Mohamed Abdealim, Hanan Anis, and Serguei Tchouragoulov

Doc ID: 272658 Received 28 Jul 2016; Accepted 07 Oct 2016; Posted 07 Oct 2016  View: PDF

Abstract: We report on an all-fiber oscillator followed by an all-fiber amplifier to produce as short as 382 femtosecond laser pulses with up to 0.9 watt average power. The oscillator is all-normal dispersion all-fiber dissipative soliton laser operating at 1030 nm, and operating in dissipative soliton mode. The amplifier stage is mainly based on a double cladding 20 µm radius Ytterbium-doped fiber pumped by up to 2.5 watts CW laser source. The optical-to-optical conversion amplifier efficiency was around 40 %. To our knowledge, this is the first time to report all-fiber mode-locked fiber laser oscillator amplified by the all-fiber amplifier.

Low cross-talk, deep subwavelength plasmonic metal/insulator/metal waveguide intersections with broadband tunability

Soon-Hong Kwon, Tae-Woo Lee, Da Eun Lee, and Young Jin Lee

Doc ID: 272935 Received 31 Jul 2016; Accepted 02 Oct 2016; Posted 04 Oct 2016  View: PDF

Abstract: We suggest a low cross-talk plasmonic cross-connector based on MIM cavity and waveguides. We separately investigate the isolated cavity mode, the waveguide mode, and the combination of cavity and waveguide modes using a finite-different time-domain method. Due to resonant tunneling and the cutoff frequency of the odd waveguide mode, our proposed structure achieves a high throughput transmission ratio and eliminates cross-talk. Furthermore, the proposed structure has a broadband tunability of 587 nm, which can be achieved by modulating the cavity air gap thickness. This structure enables the miniaturization of photonic integrated circuits and sensing applications.

Detection and upconversion of three-dimensional MMW/THz images to the visible

Avihai Aharon (Akram), Daniel Rozban, avi Klein, Amir Abramovich, Yitzhak Yitzhaky, and Natan Kopeika

Doc ID: 273711 Received 15 Aug 2016; Accepted 02 Oct 2016; Posted 04 Oct 2016  View: PDF

Abstract: We present a novel and inexpensive technique to obtain a three-dimensional (3D) millimeter wave (MMW) and terahertz (THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz radiation to the visual band using a very inexpensive miniature glow discharge detector (GDD), and a silicon photodetector. We present MMW/THz upconversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results show better response time and better sensitivity compared to the electronic detection performed previously. By using miniature plasma indicator lamps for upconversion instead of much larger plasma discharges, sensitivity is improved by about 9 orders of magnitude over that of the latter because very large internal signal amplification is obtained. Furthermore, in this work we perform also frequency modulation continuous wave (FMCW) radar detection based on this method using a GDD lamp, and a photodetector to measure GDD light emission. By using FMCW detection, the range in addition to the intensity at each pixel can be obtained, thus yielding the 3D image. The GDD acts as a heterodyne mixer not only electronically but also optically. This technique provides an MMW/THz 3D image upconverted to the visible, with much improved sensitivity and speed as compared to the pure electronic detection.

Ultrafast nonlinear absorption and nonlinear refraction in few-layer oxidized black phosphorus

Han Zhang, Shunbin Lu, Yanqi Ge, Zhengbo Sun, Zongyu Huang, Rui Cao, Chujun Zhao, Shuangchun Wen, Dianyuan Fan, and Jianqing Li

Doc ID: 273934 Received 17 Aug 2016; Accepted 29 Sep 2016; Posted 04 Oct 2016  View: PDF

Abstract: We experimentally investigated the nonlinear optical response in few-layer oxidized black phosphorus (OBP) by femto-second Z-scan measurement technique, and found that OBP not only possesses strong ultrafast saturable absorption but also nonlinear self-defocusing effect that is absent in BP. The saturable absorption property mainly origin from the direct band structure which is still maitained in OBP. The emergence of self-defocusing might originate from the combined consequences of the oxygen induced defects in BP. Our experimental findings might constitute the first experimental evidence on how to dynamically tune its nonlinear property, offering an inroad in tailoring its optical properties through chemical modification (oxidation, introducing defects, etc). The versatile ultrafast nonlinear optical properties (saturable absorption and self-defocusing) imply a significant potential of the layered OBP in the development of unprecedented optoelectronic devices, such as mode-lockers, optical switchers, laser beam shaper, wavelength converter etc.

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