2017
2017
-
Record 229 of
Title:Highly strain and bending sensitive microtapered long-period fiber gratings
Author(s):Ren, Kaili(1,2); Ren, Liyong(1); Liang, Jian(1); Kong, Xudong(1); Ju, Haijuan(1); Wu, Zhaoxin(2)Source: IEEE Photonics Technology Letters Volume: 29 Issue: 13 DOI: 10.1109/LPT.2017.2702573 Published: July 2017Abstract:A microtapered long-period fiber grating (MTLPFG) is fabricated successfully by periodically tapering a standard single-mode fiber with CO2 laser heating source. This can be done by taking advantage of that the effective index difference between the core mode and the cladding modes is changed periodically during microtapering. High fabrication reproducibility and MTLPFGs quality can be achieved by this CO2 laser-heater-based fabrication scheme. In addition, the strain, bending, and liquid-level sensing characteristics of the MTLPFGs are investigated experimentally. Compared with the conventional long-period fiber gratings, it is found that the strain and bending sensitivities of fabricated MTLPFGs are improved by factors of about 10 and 5, respectively. Considering the simple and flexible fabrication process as well as the high quality and sensitivity of fabricated MTLPFGs, we believe that this may offer a simpler and alternative choice to current filters or sensing applications. ? 2017 IEEE.Accession Number: 20173003982025 -
Record 230 of
Title:Evaluation of the un-eliminated laser phase noise induced by interferometer imbalance in self-homodyne coherent optical RF receivers
Author(s):Zhang, Huixing(1,2); Wen, Aijun(1); Gao, Yongsheng(1); Zhang, Song(1); Xiang, Shuiying(1); Lin, Lin(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10244 Issue: DOI: 10.1117/12.2264227 Published: 2017Abstract:Coherent optical RF receivers constructed in self-homodyne configurations have gained considerable attention due to its simplicity and cost-efficiency. Rigorous symmetry is required in such system to suppress the laser phase noise. A method for evaluation of the un-eliminated laser phase noise in self-homodyne coherent optical RF receivers has been presented in this paper. In our proposed scheme, the un-eliminated laser phase noise is acquired by simply inserting an FBG in the in-phase arm and is found to be dependent on the interferometer asymmetry, i.e., the path imbalance of the interferometer arms. With series of simulations, the variance of the un-eliminated laser phase noise obtained by our method becomes larger when the path imbalance is increasing. The simulation results show that, variance increases with the asymmetrical time delays of two interferometer arms. Therefore, this method is very helpful in obtaining further insight into the system symmetry and is also a good guidance for the adjustment of the interferometer architecture to achieve the optimized path equality. ? 2017 SPIE.Accession Number: 20171503546567 -
Record 231 of
Title:Transmitting volume Bragg gratings in PTR glass written with femtosecond Bessel beams
Author(s):Cheng, G.H.(1); Zhang, Y.J.(1); Liu, Q.(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10173 Issue: DOI: 10.1117/12.2268292 Published: 2017Abstract:Transmitting volume Bragg gratings were fabricated in photo-thermo-refractive glass using femtosecond laser Bessel beams and thermal treatment. The phase contrast images of gratings under different writing power were investigated before and after annealing. Microstructures composed of nano-sized crystals were observed in the exposed regions. Optimized writing power (100 mW) achieved dense nano-crystals distribution. A maximum diffraction efficiency of 92.36% was achieved with 1 mm grating thickness at period of 5 μm. ? 2017 SPIE.Accession Number: 20174904498308 -
Record 232 of
Title:Effects of Spatial Electrons on Signal-Noise-Ratio of a X-ray Communication System
Author(s):Li, Yao(1,2); Su, Tong(1,2); Sheng, Li-Zhi(1); Qiang, Peng-Fei(1,2); Xu, Neng(1,2,3); Li, Lin-Sen(1,2,4); Zhao, Bao-Sheng(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 11 DOI: 10.3788/gzxb20174611.1106002 Published: November 1, 2017Abstract:A model of electron interacting with nested X-ray focusing optics was designed firstly. Then the process of electrons interacting with coating material of X-ray focusing optics and the quantum efficiency of X-ray source by using a Monte Carlo N Particle transport code was analysized. Simulation results accord well with the analyze results. Finally, a silicon drift detector, which has an energy resolution of 125 eV was used to analysis the energy spectrum in the focal point. In the detecting part, X-ray photons are composed of two parts, signal photons generated by the X-ray source and noisy X-ray photons generated from nested X-ray focusing optics' coating material. According to different conditions of X-ray source and electron gun voltage, the number of signal photon, noisy photon and signal to noise ratio of the X-ray communication demonstration system then can be calculated. Experiment and calculate results show that nested X-ray focusing optics can effectively filter spatial particles, which will optimize the signal to noise ratio of X-ray communication system. When the number of incident electrons is about 1×108 counts per second with an energy distribution from 1~20 keV, signal to noise ratio of the X-ray communication demonstration system can reach at least 15.1 dB. These results will provide foundations for optimizing the core parameters of X-ray communication system in the future. ? 2017, Science Press. All right reserved.Accession Number: 20175104560097 -
Record 233 of
Title:Numerical investigation of a microfiberplane-grating composite optical waveguide for gas refractive index sensing
Author(s):Ma, Chengju(1); Ren, Liyong(2); Guo, Wenge(1); Fu, Haiwei(1); Xu, Yiping(3); Liu, Yinggang(1); Wen, Jin(1)Source: Applied Optics Volume: 56 Issue: 14 DOI: 10.1364/AO.56.003984 Published: May 10, 2017Abstract:In this paper, we propose a microfiber-plane-grating composite optical waveguide (MPGCOW), which is formed by immobilizing a tapered microfiber on the surface of a plane grating with one defect, for gas refractive index (RI) sensing. Its optical properties and gas RI sensing properties are investigated by the finite difference time domain method. Results show that the MPGCOW has a photonic stop band and is very sensitive to the ambient gas RI variation. The largest gas RI sensing sensitivity of 486.67 nm/RIU and detection limit of 2 × 10-6 are obtained by immersing the structure in the mixture gas of N2 and He with various mixture ratios. ? 2017 Optical Society of America.Accession Number: 20172003675753 -
Record 234 of
Title:Space X-ray Communication Link Modeling and Power Analysis
Author(s):Su, Tong(1,2); Li, Yao(1,2); Sheng, Li-Zhi(1); Qiang, Peng-Fei(1,2); Chen, Chen(1,2); Xu, Neng(1,2,3); Zhao, Bao-Sheng(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 10 DOI: 10.3788/gzxb20174610.1035001 Published: October 1, 2017Abstract:X-ray communication(Xcom) is a method which applying X-ray as carriers to transmit information in space. After the concept of Xcom was produced by Dr Keith, many institutions and scientists have conducted researches on Xcom and achieved fruitful results. However, most researches are focused on the key devices of Xcom, such as the X-ray emit source, the antenna and the detector, there is nearly no theoretical model for space X-ray communication. In this article, we focused on the power transmission process of space Xcom. To begin with, we analysised the signal channel and transmission model based on the additional gussian white noise(AWGN) model and free space attenuation, established the power transmission equation and link model. Then we analysised the error source of Xcom, established the noise model based on single photon detectors and also given the main noise sources. In other words, we can built mathematical relationship between the power of X-ray source, transmitting distance&speed and bit-error-ration (BER). Finally, we testified the signal photons of Micochannel Plate(MCP) detector output against various anode voltage and modulations. The results accord well with the theoretical analysis, and the power transmission equation and BER model can explain the Xcom process well too. Based on this transmission theory, we can calculate the emit X-ray power against various transmission distance and BER level respectively. As a result, three key parameters which judging a wireless optical communication system have been given as well as the theoretical model. Simulation results showed that with a constant photons flow, Pulse Position Modulation(PPM) has a better BER level than On-Off Keying(OOK) modulation. When the transmission distance is about 10 km, in order to achieve BER less than 10-6 level, the power consumption of X-ray is less than 1mW. According to the power transmission model, in order to improve the BER level of Xcom system, we need a lower dark current detector, an advanced modulation and more transmitting power. These theoretical and experiment results could provide foundations for optimizing the core parameters of XCOM system in our future works. ? 2017, Science Press. All right reserved.Accession Number: 20174504368412 -
Record 235 of
Title:High energy mode-locked Yb-doped fiber laser with Bi2Te3 deposited on tapered-fiber
Author(s):Li, Lu(1); Wang, Yonggang(2,3); Wang, Xi(3); Lin, Tao(4); Sun, Hang(4)Source: Optik Volume: 142 Issue: DOI: 10.1016/j.ijleo.2017.06.029 Published: August 2017Abstract:The report presents the high energy mode-locking operation in an all-normal-dispersion Yb-doped mode-locked fiber laser based on evanescent field interaction with tapered fiber deposited with Bi2Te3 topological insulator. Different from most of solution processing methods, Bi2Te3 film is deposited on the tapered fiber by pulsed laser deposition (PLD) technology. In this way, it can bring less non-saturable losses and contact to the fiber better. By incorporating this novel fiber-taper Bi2Te3 saturable absorber into Yb-doped fiber laser cavity, a repetition rate of 6.2?MHz mode-locked fiber laser is achieved. The maximum single pulse energy of 2?nJ is obtained. The results indicate that fiber-taper Bi2Te3 saturable absorber possesses potentiality for high power mode-locked fiber laser applications. ? 2017 Elsevier GmbHAccession Number: 20172403790375 -
Record 236 of
Title:Intrinsic reduction the depolarization loss in electro-optical Q-switched laser using a rectangular KD*P crystal
Author(s):Yin, Xingliang(1); Jiang, Menghua(1); Sun, Zhe(2); Hui, Yongling(1); Lei, Hong(1); Li, Qiang(1)Source: Optics Communications Volume: 398 Issue: DOI: 10.1016/j.optcom.2017.04.048 Published: September 1, 2017Abstract:We presented the first demonstration of a new structure KD*P crystal as electro-optic switch, in which the thermal depolarization loss was intrinsically reduced. The thermally induced birefringence and depolarization of both cylindrical and rectangular crystalline structure were simulated. The higher pulse energy or average power output was achieved in the diode pumped E-O Q-switched laser using a rectangular KD*P crystal. At the repetition rate of 100 Hz, the maximum average output power was 27.2 W at 145 A pump current, corresponding to the pulse energy was 272 mJ with pulse width of 65 ns and the beam quality of M2=20.4. Comparing the highest average power or corresponding single pulse energy, the laser with the rectangular KD*P crystal was two times of the laser with the traditional cylindrical KD*P crystal. ? 2017 Elsevier B.V.Accession Number: 20171703612462 -
Record 237 of
Title:Efficient wavelength-tunable gain-switching and gain-switched mode-locking operation of a heavily Er3+-doped ZBLAN mid-infrared fiber laser
Author(s):Shen, Yanlong(1,2,3,4,5); Wang, Yishan(1,5); Luan, Kunpeng(3); Chen, Hongwei(3); Tao, Mengmeng(3); Si, Jinhai(2)Source: IEEE Photonics Journal Volume: 9 Issue: 4 DOI: 10.1109/JPHOT.2017.2721998 Published: August 2017Abstract:We report on an efficient wavelength-tunable gain-switched and gain-switched mode-locked Er3+-doped double-clad fiber laser with a linear cavity. Stable gain-switching and gain-switched mode-locking were achieved with slope efficiencies of 28.6% and 34.5% with respect to launched pump power, respectively. The gain-switched laser pulses were generated with a maximum average output power of around 110 mW, pulse width of 661.2 ns, and calculated peak power of ～16.5 W at a repetition rate of 10 kHz. At the same repetition, the gain-switched mode-locked laser pulses were generated with a maximum average output power of around 514 mW, subpulse repetition rate of ～30.7 MHz, and peak power of higher than 154 W at a repetition rate of 10 kHz when the wavelength was tuned to 2.78 μm. This is, to the best of our knowledge, the first demonstration of a gain-switched self-started mode-locked fiber laser near 3 μm. ? 2017 IEEE.Accession Number: 20172803930754 -
Record 238 of
Title:SNR-based adaptive acquisition method for fast Fourier ptychographic microscopy
Author(s):Pan, An(1,2); Zhang, Yan(1,2); Li, Maosen(3); Zhou, Meiling(1,2); Min, Junwei(1); Lei, Ming(1); Yao, Baoli(1)Source: arXiv Volume: Issue: DOI: Published: September 19, 2017Abstract:Fourier ptychographic microscopy (FPM) is a computational imaging technique with both high resolution and large field-of-view. However, the effective numerical aperture (NA) achievable with a typical LED panel is ambiguous and usually relies on the repeated tests of different illumination NAs. The imaging quality of each raw image usually depends on the visual assessments, which is subjective and inaccurate especially for those dark field images. Moreover, the acquisition process is really time-consuming. In this paper, we propose a SNR-based adaptive acquisition method for quantitative evaluation and adaptive collection of each raw image according to the signal-to-noise ration (SNR) value, to improve the FPM's acquisition efficiency and automatically obtain the maximum achievable NA, reducing the time of collection, storage and subsequent calculation. The widely used EPRY-FPM algorithm is applied without adding any algorithm complexity and computational burden. The performance has been demonstrated in both USAF targets and biological samples with different imaging sensors respectively, which have either Poisson or Gaussian noises model. Further combined with the sparse LEDs strategy, the number of collection images can be shorten to around 25 frames while the former needs 361 images, the reduction ratio can reach over 90%. This method will make FPM more practical and automatic, and can also be used in different configurations of FPM. Copyright ? 2017, The Authors. All rights reserved.Accession Number: 20200445986 -
Record 239 of
Title:Two-dimensional matter-wave solitons and vortices in competing cubic-quintic nonlinear lattices
Author(s):Gao, Xuzhen(1,2); Zeng, Jianhua(1)Source: arXiv Volume: Issue: DOI: Published: June 8, 2017Abstract:The nonlinear lattice-a new and nonlinear class of periodic potentials-was recently introduced to generate various nonlinear localized modes. Several attempts failed to stabilize two-dimensional (2D) solitons against their intrinsic critical collapse in Kerr media. Here, we provide a possibility for supporting 2D matter-wave solitons and vortices in an extended setting-the cubic and quintic model-by introducing another nonlinear lattice whose period is controllable and can be different from its cubic counterpart, to its quintic nonlinearity, therefore making a fully 'nonlinear quasi-crystal'. A variational approximation based on Gaussian ansatz is developed for the fundamental solitons and in particular, their stability exactly follows the inverted Vakhitov-Kolokolov stability criterion, whereas the vortex solitons are only studied by means of numerical methods. Stability regions for two types of localized mode-the fundamental and vortex solitons-are provided. A noteworthy feature of the localized solutions is that the vortex solitons are stable only when the period of the quintic nonlinear lattice is the same as the cubic one or when the quintic nonlinearity is constant, while the stable fundamental solitons can be created under looser conditions. Our physical setting (cubic-quintic model) is in the framework of the Gross-Pitaevskii equation (GPE) or nonlinear Schr?dinger equation, the predicted localized modes thus may be implemented in Bose-Einstein condensates and nonlinear optical media with tunable cubic and quintic nonlinearities. Copyright ? 2017, The Authors. All rights reserved.Accession Number: 20200530121 -
Record 240 of
Title:Thermal Stress and Smile of Conduction-cooled High Power Semiconductor Laser Arrays
Author(s):Lu, Yao(1,2); Nie, Zhi-Qiang(1); Chen, Tian-Qi(1,2); Zhang, Pu(1); Xiong, Ling-Ling(1); Wu, Di-Hai(1,2); Li, Xiao-Ning(3); Wang, Zhen-Fu(1); Liu, Xing-Sheng(1,3)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 9 DOI: 10.3788/gzxb20174609.0914001 Published: September 1, 2017Abstract:Finite element analysis model of the conduction-cooled package high power semiconductor lasers were established respectively to analyze normal stress, shear stress and displacement in reflowing process and operating process independently. With the help of analytical solution model, the cause and the distribution of thermal stress and smile were analyzed. The results show that shear stress is the origin of other thermo-mechanical behavior in reflowing process due to coefficient thermal expansion mismatch, while both coefficient thermal expansion mismatch and temperature gradient affect the thermal stress and displacement in operating process. In order to obtain the accurate result, the residual stress and displacement of reflowing process were considered as the initial condition in operating finite element analysis simulation, and the thermal stress and smile were simulated. The influence of heat sink temperature on smile was studied with finite element analysis and experiment. The result shows operating process has great impact on smile and results in worse smile, and with the rising of temperature of heat sink, smile also becomes larger. ? 2017, Science Press. All right reserved.Accession Number: 20174304293745