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Optics Express

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https://www.readbyqxmd.com/read/29609415/modulation-format-identification-enabled-by-the-digital-frequency-offset-loading-technique-for-hitless-coherent-transceiver
#1
Songnian Fu, Zuying Xu, Jianing Lu, Hexun Jiang, Qiong Wu, Zhouyi Hu, Ming Tang, Deming Liu, Calvin Chun-Kit Chan
We propose a blind and fast modulation format identification (MFI) enabled by the digital frequency-offset (FO) loading technique for hitless coherent transceiver. Since modulation format information is encoded to the FO distribution during digital signal processing (DSP) at the transmitter side (Tx), we can use the fast Fourier transformation based FO estimation (FFT-FOE) method to obtain the FO distribution of individual data block after constant modulus algorithm (CMA) pre-equalization at the receiver side, in order to realize non-data-aided (NDA) and fast MFI...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609414/optical-amplification-of-airy-beams-by-photorefractive-two-wave-mixing
#2
Xu Yang, Meirong Wang, Cibo Lou, Peng Zhang
We propose and demonstrate nonlinear amplifications of self-accelerating Airy beams by two-wave mixing in photorefractive crystals both numerically and experimentally. By employing a broad Gaussian beam as the pump beam, we show that weak signal Airy beams can be significantly amplified under both diffusion and drift mechanisms. It is revealed that not only higher optical gains but also faster response time can be achieved in the presence of an external electric field, where the drift mechanism dominates. We verify that the self-accelerating and self-healing characteristics of the Airy beams are well preserved during the nonlinear amplification...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609413/point-spread-function-manipulation-of-the-swept-source-optical-coherence-tomography-through-temporal-phase-modulation
#3
Chi Zhang, Rui Zhu, Kenneth K Y Wong
Recent breakthroughs in microscopy have surpassed Abbe's spatial diffraction limit, especially in the regime of fluorescence imaging. Microcopy's depth-imaging relative tomography is, however, still confined to basic imaging quality, which is limited by the Fourier bandwidth. In this paper, we explore the analogy between spatial microscopy and temporal tomography based on the space-time duality, and hence enlighten the advancement of tomography. As a proof-of-principle demonstration, an all-optical manipulation of the point-spread function (PSF) of a swept-source optical coherence tomography (OCT) is performed based on temporal phase modulation...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609412/characterization-of-spectral-domain-oct-with-autocorrelation-interference-response-for-axial-resolution-performance
#4
Sucbei Moon, Yueqiao Qu, Zhongping Chen
We present a class of novel system characterization methods for spectral-domain optical coherence tomography (SD-OCT) particularly on getting optimized axial resolution performance. Our schemes uniquely utilize the autocorrelation interference response, also known as the self-interference product, which is generated by the optical fields from the imaging sample in automatic interferences. In our methods, an autocorrelation-inducing calibration sample was prepared which was made by sandwiching glass plates. OCT images of the calibration sample were captured by an SD-OCT system under testing...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609411/theoretical-study-of-pyramid-sizes-and-scattering-effects-in-silicon-photovoltaic-module-stacks
#5
Oliver Höhn, Nico Tucher, Benedikt Bläsi
Front side pyramids are the industrial standard for wafer based monocrystalline silicon solar cells. These pyramids fulfill two tasks: They act as anti-reflective structure on the one hand and as a light-trapping structure on the other hand. In recent development smaller pyramids with sizes below 1 µm attract more and more interest. In this paper an optical analysis of periodically arranged front side pyramids is performed. The impact on the reflectance as well as on the useful absorption within the solar cell is investigated depending on the pyramids size, the amount of additional scattering in the system and the quality of the rear side reflector...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609410/physical-model-for-multiple-scattered-space-borne-lidar-returns-from-clouds
#6
Kaori Sato, Hajime Okamoto, Hiroshi Ishimoto
A practical model for determining the time-dependent lidar attenuated backscattering coefficient β was developed for application to global lidar data. An analytical expression for the high-order phase function was introduced to reduce computational cost for simulating the angular distribution of the multiple scattering irradiance. The decay rate of the multiple scattering backscattered irradiance was expressed by incorporating the dependence on the scattering angle and the scattering order based on the path integral approach...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609409/polarization-management-based-on-dipolar-interferences-and-lattice-couplings
#7
M Q Liu, C Y Zhao, B X Wang
We have achieved efficient polarization manipulations based on dipolar interferences and lattice couplings in one-dimensional cylindrical metalattices. First, we employ the scattering asymmetry factor g to quantify the directional scattering ability and find the maximum |g|max =1/2 for a cylinder with effective excitations of electric and magnetic dipoles simultaneously. Further, the strong negative-g (gp = -0.38) for p-polarization and positive-g (gs = 0.68) for s-polarization are obtained within a narrow visible band using c-Si with experimental data...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609408/integration-of-an-insb-photodetector-on-si-via-heteroepitaxy-for-the-mid-infrared-wavelength-region
#8
Bo Wen Jia, Kian Hua Tan, Wan Khai Loke, Satrio Wicaksono, Soon Fatt Yoon
In this study, InSb p-i-n photodetectors with In0.82 Al0.18 Sb barrier layers were grown on a (100) 6° offcut Si substrate by heteroepitaxy via an AlSb/GaSb buffer. Based on an interfacial misfit array growth mode, the dislocations at the GaSb/Si and InSb/AlSb interfaces accommodated the lattice mismatch. The In0.82 Al0.18 Sb barrier layer increased the 77 K R0 A of the detector. From 180 K to 300 K, the generation-recombination mechanism dominated the dark current generation in the detector and surface leakage became dominant below 120 K...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609407/window-split-structured-frequency-domain-kalman-equalization-scheme-for-large-pmd-and-ultra-fast-rsop-in-an-optical-coherent-pdm-qpsk-system
#9
Zibo Zheng, Nan Cui, Hengying Xu, Xiaoguang Zhang, Wenbo Zhang, Lixia Xi, Yuanyuan Fang, Liangchuan Li
A window-split frequency domain Kalman scheme is proposed in this paper for the equalization of large polarization mode dispersion (PMD) and ultra-fast rotation of state-of-polarization (RSOP) which is an extreme environment due to the Kerr effect and the Faraday effect under the lightning strike near the fiber cables. In order to carry out the proposed Kalman scheme, we give a simplified and equivalent fiber channel model as a replacement for the general model of the polarization effect of the co-existence of PMD and RSOP...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609406/ultraviolet-light-induced-terahertz-modulation-of-an-indium-oxide-film
#10
Hongyu Ji, Bo Zhang, Wei Wang, Longfeng Lv, Jingling Shen
Active ultraviolet light-induced terahertz modulation of an indium oxide film is investigated. A large absorption modulation of ~66% is achieved upon illumination with a low intensity UV laser (11 mW/cm2 ). The interaction between indium oxide and a flexible metamaterial structure is investigated owing to the large UV-induced enhancement of photo carriers observed in an indium oxide film. We are able to realize absorption peak shifts of 37 GHz by changing the UV excitation light intensity. We also propose a multi-frequency switch by building a circular metallic split ring resonator whose gaps are filled with silicon, germanium, and indium oxide...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609405/velocimetry-of-fast-microscopic-liquid-jets-by-nanosecond-dual-pulse-laser-illumination-for-megahertz-x-ray-free-electron-lasers
#11
Marie Luise Grünbein, Robert L Shoeman, R Bruce Doak
To conduct X-ray Free-Electron Laser (XFEL) measurements at megahertz (MHz) repetition rates, sample solution must be delivered in a micron-sized liquid free-jet moving at up to 100 m/s. This exceeds by over a factor of two the jet speeds measurable with current high-speed camera techniques. Accordingly we have developed and describe herein an alternative jet velocimetry based on dual-pulse nanosecond laser illumination. Three separate implementations are described, including a small laser-diode system that is inexpensive and highly portable...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609404/dynamics-characteristics-of-highly-charged-ions-in-laser-produced-sic-plasmas
#12
Qi Min, Maogen Su, Shiquan Cao, Duixiong Sun, Gerry O'Sullivan, Chenzhong Dong
The radiation and dynamic properties of C VI, C V, Si VI and Si V ions from laser-produced SiC plasmas in a vacuum are studied both experimentally and theoretically. The EUV emission spectra of SiC plasmas are measured using the spatio-temporally resolved laser-produced plasma spectroscopy technique. To explore the dynamic evolution of highly-charged ions in such plasmas, an extended radiation hydrodynamics model is developed. The comparison of theoretical and experimental time-space evolved spectral profiles provides the temporal evolution of plasma temperature and electron density, the distribution of various transient ions and their velocities...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609403/single-chip-source-free-terahertz-spectroscope-across-0-04-0-99-thz-combining-sub-wavelength-near-field-sensing-and-regression-analysis
#13
Xue Wu, Kaushik Sengupta
This paper demonstrates a methodology to miniaturize THz spectroscopes into a single silicon chip by eliminating traditional solid-state architectural components such as complex tunable THz and optical sources, nonlinear mixing and amplifiers. The proposed method achieves this by extracting incident THz spectral signatures from the surface of an on-chip antenna itself. The information is sensed through the spectrally-sensitive 2D distribution of the impressed current surface under the THz incident field. By converting the antenna from a single-port to a massively multi-port architecture with integrated electronics and deep subwavelength sensing, THz spectral estimation is converted into a linear estimation problem...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609402/1-6-%C3%AE-m-dissipative-soliton-fiber-laser-mode-locked-by-cesium-lead-halide-perovskite-quantum-dots
#14
Bang Liu, Lei Gao, Wei Wei Cheng, Xiao Sheng Tang, Chao Gao, Yu Long Cao, Yu Jia Li, Tao Zhu
We demonstrate a stable, picosecond fiber laser mode-locked by cesium lead halide perovskite quantum dots (CsPbBr3 -QDs). The saturable absorber is produced by depositing the CsPbBr3-QDs nanocrystals onto the endface of a fiber ferrule through light pressure. A balanced two-detector measurement shows that it has a modulation depth of 2.5% and a saturation power of 17.29 MW/cm2 . After incorporating the fabricated device into an Er3+ -doped fiber ring cavity with a net normal dispersion of 0.238 ps2 , we obtain stable dissipative soliton with a pulse duration of 14...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609401/broadband-tunable-terahertz-absorber-based-on-vanadium-dioxide-metamaterials
#15
Zhengyong Song, Kai Wang, Jiawen Li, Qing Huo Liu
An active absorption device is proposed based on vanadium dioxide metamaterials. By controlling the conductivity of vanadium dioxide, resonant absorbers are designed to work at wide range of terahertz frequencies. Numerical results show that a broadband terahertz absorber with nearly 100% absorptance can be achieved, and its normalized bandwidth of 90% absorptance is 60% under normal incidence for both transverse-electric and transverse-magnetic polarizations when the conductivity of vanadium dioxide is equal to 2000 Ω-1 cm-1 ...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609400/organic-inorganic-hybrid-microdisk-laser-with-dye-and-silica-mixed-doping-prepared-by-ink-jet-printing-method
#16
Yuya Mikami, Hiroaki Yoshioka, Soichiro Ryu, Naoya Nishimura, Yuji Oki
We developed an ink-jet printing method for fabricating inorganic microdisks at room temperature, which is much lower than the melting point of solid-state inorganic oxide, and have fabricated an organic-inorganic hybrid microdisk laser. Silica was used as the inorganic disk material, and microdisk-shaped aggregates were formed by the ink-jet printing method using a solution in which nanosilica particles were dispersed in propylene glycol monomethylether (PGME) solvent. Then, a microdisk capable of laser oscillation was also prepared by preliminarily adding the laser dye rhodamine 6G to the ink to form a mixed organic material...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609399/size-and-edge-dependence-of-two-photon-absorption-in-rectangular-graphene-quantum-dots
#17
Xiaobo Feng, Yonggang Qin, Yu Liu
The size and edge-dependence of two-photon absorption (TPA) for rectangular graphene quantum dots (GQDs) is investigated theoretically in the framework of Dirac equation under hard wall boundary conditions. The TPA cross section associated with interband transitions around K point is derived and the transition selection rules are obtained. Results reveal that when the size of zigzag-edge M = 3M0 ± 1 (M0 is an integer), the GQD exhibits a semiconductor while for M = 3M0 it is metallic. For semiconducting rectangular GQDs, TPA is tuned by the sizes of both edges in GQDs and the armchair-edge dimension contributes more to TPA...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609398/3d-shape-measurement-in-the-presence-of-strong-interreflections-by-epipolar-imaging-and-regional-fringe-projection
#18
Huijie Zhao, Yang Xu, Hongzhi Jiang, Xudong Li
A 3D shape measurement method in the presence of strong interreflections is presented. Traditional optical 3D shape measurement methods such as fringe projection profilometry (FPP) cannot measure regions that contain strong interreflections, which result in 3D shape measurement failure. In the proposed method, epipolar imaging with speckle patterns is utilized to eliminate the effects of interreflections and obtain the initial 3D shape measurement result. Regional fringe projection based on the initial measurement result is further applied to achieve high-accuracy measurement...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609397/highly-efficient-generation-of-0-2-mj-terahertz-pulses-in-lithium-niobate-at-room-temperature-with-sub-50-fs-chirped-ti-sapphire-laser-pulses
#19
Xiao-Jun Wu, Jing-Long Ma, Bao-Long Zhang, Shu-Su Chai, Zhao-Ji Fang, Chen-Yi Xia, De-Yin Kong, Jin-Guang Wang, Hao Liu, Chang-Qing Zhu, Xuan Wang, Cun-Jun Ruan, Yu-Tong Li
We demonstrate generation of 0.2 mJ terahertz (THz) pulses in lithium niobate driven by Ti:sapphire laser pulses at room temperature. Employing tilted pulse front technique, the 800 nm-to-THz energy conversion efficiency has been optimized to 0.3% through chirping the sub-50 fs pump laser pulses to overcome multi-photon absorption and to extend effective interaction length for phase matching. Our approach paves the way for mJ-level THz generation via optical rectification using existing Ti:sapphire laser systems which can deliver Joule-level pulse energy with sub-50 fs pulse duration...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609396/control-of-the-coherence-behavior-in-a-sfg-interferometer-through-the-multipump-phases-command
#20
P Darré, L Lehmann, L Grossard, L Delage, F Reynaud
In this paper, we report on a novel method to control the coherence behavior in a sum frequency generation interferometer powered by two independent pump lines. At the output of the interferometer, the two incoherent fringe patterns must be superimposed to maximize the contrast. The first step consists in canceling the differential group delay. The second one uses the phase control on one pump to synchronize the fringe patterns. This innovative method is experimentally demonstrated with a setup involving a 1544 nm signal and two pump lines around 1064 nm leading to a converted signal around 630 nm...
March 19, 2018: Optics Express
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