2016

• Record 145 of
  
  Title:Optical waveguides fabricated by nitrogen ion implantation in fused silica
  
  Author(s):Liu, Chun-Xiao(1); Fu, Li-Li(2); Zheng, Rui-Lin(1); Guo, Hai-Tao(3); Zhou, Zhi-Guang(3); Li, Wei-Nan(3); Lin, She-Bao(4); Wei, Wei(1)
  Source: Optical Engineering  Volume: 55  Issue: 2  DOI: 10.1117/1.OE.55.2.027105  Published: February 1, 2016  
  Abstract:We report on the fabrication of waveguides in fused silica using 4.5-MeV nitrogen ion implantation with a fluence of 5.0×1014 ions/cm2. The prism-coupling method was employed to measure the effective refractive indices of guiding modes at the wavelengths of 632.8 and 1539 nm. The effective refractive indices of the first few modes were higher than that of the substrate. The refractive index profiles at 632.8 and 1539 nm were reconstructed by the reflectivity calculation method. Positive index changes were induced in the waveguide layers. The end-face coupling method was used to measure the near-field light intensity distributions at the wavelength of 632.8 nm and the finite-difference beam propagation method was applied to simulate the guided mode profile at the wavelength of 1539 nm. The waveguide structures emerge as candidates for integrated photonic devices. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).
  Accession Number: 20160902042183
• Record 146 of
  
  Title:Real-time static polarimetric image dehazing technique based on atmospheric scattering correction
  
  Author(s):Xia, Pu(1,2); Liu, Xue-Bin(1)
  Source: Beijing Youdian Daxue Xuebao/Journal of Beijing University of Posts and Telecommunications  Volume: 39  Issue: 6  DOI: 10.13190/j.jbupt.2016.06.006  Published: December 1, 2016  
  Abstract:In order to realize real-time static image recovery under hazy weather, a new theory of polarimetric dehazing was presented based on study of the atmospheric scattering model, analyzation on the effects of aerosols and the method of atmospheric scattering correction. The polarimetric information is obtained statically from the original images by Stokes equation and the Muller matrix. The sky region is extracted in real time based on the polarimetric measurement of the hole image. The influence of the range of polarization orientation angle and the threshold of air light intensity are analyzed based on the extraction result. The real time static polarimetric image dehazing method can be realized with fixed linear polarimetric images. No manual operation or subjective evaluation is needed which greatly simplifies the dehazing process. The accuracy of image recovery is increased by solving the problem of the estimation of the global parameters. The real time static polarimetric dehazing method provides a new theoretical and technical way for high-resolution, high stability and real-time image recovery under hazy weather. © 2016, Editorial Department of Journal of Beijing University of Posts and Telecommunications. All right reserved.
  Accession Number: 20170703354416
• Record 147 of
  
  Title:Analysis of dual-end-pumped Nd3+-doped index-crossover gain guided-index antiguided fiber laser
  
  Author(s):Shen, Xiao(1,2); Wei, Wei(1); Zou, Hui(1); Zhang, Liaolin(1)
  Source: Optics Communications  Volume: 366  Issue:   DOI: 10.1016/j.optcom.2015.12.063  Published: May 1, 2016  
  Abstract:A dual-end pumped Nd3+-doped index-crossover gain guided-index antiguided (IGG-IAG) fiber laser is analyzed in theory. Pump light propagation and output laser characteristics are both explored by solving the related rate equations. Simulation results show that pump power confined in the IGG-IAG fiber core is larger and more uniform than that of the gain-guided and index-antiguided(GG-IAG) fiber, and the optimum fiber length and the output power of the IGG-IAG fiber laser are both larger than that of GG-IAG fiber laser. The relationship between threshold pump power and doped concentration, fiber length, fiber radius is researched respectively. The analysis results give out a method for the optimal design of the IGG-IAG fiber laser. © 2015 Elsevier B.V. All rights reserved.
  Accession Number: 20160101763557
• Record 148 of
  
  Title:Gain guided and index alternate-guided fibers designed for large-mode-area and single-mode laser with higher output power and slope efficiency
  
  Author(s):Shen, Xiao(1,2); Wei, Wei(1)
  Source: Optics Express  Volume: 24  Issue: 2  DOI: 10.1364/OE.24.001089  Published: January 25, 2016  
  Abstract:A gain guided and index alternate-guided fiber (GGIA-GF) is proposed and numerically demonstrated. The conditions of single mode oscillation are analyzed based on the fiber laser parameters. The output laser power and slope efficiency of the GGIA-GF laser are derived from the improved rate equations. The results show that the output characteristics of the laser based on GGIA-GF can be greatly improved than that of the gain guided and index anti-guided fiber laser through the optimal design of the fiber laser parameters. GGIA-GF would be better applied in the field of large mode area and single mode fiber lasers. © 2016 Optical Society of America.
  Accession Number: 20161402179170
• Record 149 of
  
  Title:Measurement of excited layer thickness in highly photo-excited GaAs
  
  Author(s):Liang, Lingliang(1,2,3); Tian, Jinshou(1); Wang, Tao(1); Wu, Shengli(3); Li, Fuli(3); Gao, Guilong(1,2,3)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 10155  Issue:   DOI: 10.1117/12.2246652  Published: 2016  
  Abstract:Highly photo-excited layer thickness in GaAs is measured using a pump probe arrangement. A normally incident pump illumination spatially modulated by a mask will induce a corresponding refractive index change distribution in the depth direction due to edge scattering and attenuation absorption effect, which can deflect the probe beam passing through this excited region. Maximum deflection of the probe beam will be limited by the thickness of excited layer, and thus can also be employed to measure the thickness of the photo-excited layer of the material. Theoretical calculation confirms the experimental results. This method can find its application in measurements of photo-excited layer thickness of many kinds of materials and be significant to study the characteristics of materials in laser machining, grating and waveguide fabricating. © 2016 SPIE.
  Accession Number: 20170103223611
• Record 150 of
  
  Title:Image recombination transform algorithm for superresolution structured illumination microscopy
  
  Author(s):Zhou, Xing(1,2); Lei, Ming(1); Dan, Dan(1); Yao, Baoli(1); Yang, Yanlong(1); Qian, Jia(1); Chen, Guangde(2); Bianco, Piero R.(3)
  Source: Journal of Biomedical Optics  Volume: 21  Issue: 9  DOI: 10.1117/1.JBO.21.9.096009  Published: September 1, 2016  
  Abstract:Structured illumination microscopy (SIM) is an attractive choice for fast superresolution imaging. The generation of structured illumination patterns made by interference of laser beams is broadly employed to obtain high modulation depth of patterns, while the polarizations of the laser beams must be elaborately controlled to guarantee the high contrast of interference intensity, which brings a more complex configuration for the polarization control. The emerging pattern projection strategy is much more compact, but the modulation depth of patterns is deteriorated by the optical transfer function of the optical system, especially in high spatial frequency near the diffraction limit. Therefore, the traditional superresolution reconstruction algorithm for interference-based SIM will suffer from many artifacts in the case of projection-based SIM that possesses a low modulation depth. Here, we propose an alternative reconstruction algorithm based on image recombination transform, which provides an alternative solution to address this problem even in a weak modulation depth. We demonstrated the effectiveness of this algorithm in the multicolor superresolution imaging of bovine pulmonary arterial endothelial cells in our developed projection-based SIM system, which applies a computer controlled digital micromirror device for fast fringe generation and multicolor light-emitting diodes for illumination. The merit of the system incorporated with the proposed algorithm allows for a low excitation intensity fluorescence imaging even less than 1W/cm2, which is beneficial for the long-term, in vivo superresolved imaging of live cells and tissues. © 2016 The Authors.
  Accession Number: 20164002873467
• Record 151 of
  
  Title:A compact QCW conduction-cooled high power semiconductor laser array
  
  Author(s):Zhu, Qiwen(1,2); Zhang, Pu(1); Wang, Shuna(1); Wu, Dihai(1); Nie, Zhiqiang(1); Xiong, Lingling(1); Song, Yunfei(1); Liu, Xingsheng(1,3)
  Source: 2016 17th International Conference on Electronic Packaging Technology, ICEPT 2016  Volume:   Issue:   DOI: 10.1109/ICEPT.2016.7583125  Published: October 4, 2016  
  Abstract:With the improvement of performance and reliability, high power semiconductor lasers have been widely applied in more and more fields. Thermal management is one of the most important issues effecting the optical-electrical performance of high power semiconductor laser. Compared with liquid-cooled techniques, conduction-cooled techniques have many advantages in some special applications because it could be adaptable for extreme environments, such as high temperature and low temperature. In this paper, a compact quasi-continuous wave (QCW) conduction-cooled high power semiconductor laser array was studied. The thermal behavior of the conduction-cooled semiconductor laser array with different structure and operation parameters were carried out using finite element method (FEM). The structure parameters of G-Stack semiconductor laser array was presented and optimized. Finally, A high power semiconductor laser array with superior performance was fabricated and characterized. © 2016 IEEE.
  Accession Number: 20164502990977
• Record 152 of
  
  Title:Quasi-all-fiber high-efficiency divided chirp-pulse amplification system based on active controlling
  
  Author(s):Yu, J.(1,2); Feng, Y.(1,2,3); Duan, L.N.(1,2); Li, X.H.(4); Hu, X.H.(1,2); Zhang, T.(1); Zhang, W.(1); Wang, Y.S.(1); Yang, Z.(1); Zhao, W.(1)
  Source: IEEE Photonics Journal  Volume: 8  Issue: 1  DOI: 10.1109/JPHOT.2016.2524201  Published: February 2016  
  Abstract:We present a new high-efficiency divided chirp-pulse amplification (DCPA) system based on an actively controlled quasi-all-fiber structure. As a proof-of-principle experiment, a two-channel amplification system composed of single-mode ytterbium-doped fiber is constructed. The experimental results show that the degree of linear polarization of ∼93% is maintained after recombination and the system efficiency is up to ∼95%. In addition, the beam quality (M2 factor) is around 1.2. Moreover, the system can operate stably for a long time without performance degradation. Compared with the traditional spatial DCPA, this system exhibits some advantages, such as improved spatial adjustment, high stability, compact size, and low cost. It is demonstrated that this work paves the way to design a quasi-all-fiber high-performance pulsed laser system. © 2009-2012 IEEE.
  Accession Number: 20161502231619
• Record 153 of
  
  Title:Aberration correction for stimulated emission depletion microscopy with coherent optical adaptive technique
  
  Author(s):Yan, Wei(1,2); Yang, Yanlong(3); Li, Yang(2); Peng, Xiao(1); Lin, Danying(1); Qu, Junle(1); Ye, Tong(2)
  Source: Progress in Biomedical Optics and Imaging - Proceedings of SPIE  Volume: 9717  Issue:   DOI: 10.1117/12.2211907  Published: 2016  
  Abstract:Stimulated emission depletion microscopy (STED) has become one of the powerful research tools in the field of superresolution microscopy. As its spatial resolution is gained by phase modulation of the light field, the aberrations produced by optical systems and specimens may have negative impact on the focusing properties of two beams, especially the STED beam, resulting in reduced spatial resolution. In thick samples, the aberration effect may play an even more critical role in affecting spatial resolution. Here, we report our recent effort in correcting the aberration in STED microscopy by using coherent optical adaptive technique (COAT) so that the resolution can be improved. © 2016 SPIE.
  Accession Number: 20163302705656
• Record 154 of
  
  Title:34-fs, all-fiber all-polarization-maintaining single-mode pulse nonlinear amplifier
  
  Author(s):Yu, Jia(1,2,3); Feng, Ye(1,2,4); Cai, Yajun(1,2); Li, Xiaohui(5); Hu, Xiaohong(1,2); Zhang, Wei(1); Duan, Lina(1,2); Yang, Zhi(1); Wang, Yishan(1,3); Liu, Yuanshan(1); Zhao, Wei(1,3)
  Source: Optics Express  Volume: 24  Issue: 15  DOI: 10.1364/OE.24.016630  Published: July 25, 2016  
  Abstract:We present an all-fiber all-polarization-maintaining (PM) single mode (SM) fiber pulse nonlinear amplification system. The seed laser with a repetition rate of 200 MHz is amplified by two-section erbium-doped PM gain fibers with different peak-absorption rate. The amplified pulse duration can be compressed into 34-fs with 320-mW output power, which corresponds to 1.6-nJ pulse energy and approximate 23.5-kW peak power. In addition, the amplified and compressed pulse is further coupled into the high nonlinear fiber and an octave-spanning supercontinuum generation can be obtained. To the best of our knowledge, it is the highest peak power and the shortest pulse duration obtained in the field of all-fiber all-PM SM pulse-amplification systems. ©2016 Optical Society of America.
  Accession Number: 20163102656276
• Record 155 of
  
  Title:Threshold characteristics analysis of dual-end-pumped Nd3+-doped gain-guided and index-antiguided fiber lasers
  
  Author(s):Shen, Xiao(1,2); Wei, Wei(1)
  Source: MATEC Web of Conferences  Volume: 61  Issue:   DOI: 10.1051/matecconf/20166106011  Published: June 28, 2016  
  Abstract:An analytical model for dual-end-pumped Nd3+-doped gain-guided and index-antiguided (GG-IAG) fiber laser is established. The corresponding analytical expression of the threshold pump power is obtained by solving the improved rate equations. Pump light propagation and threshold characteristics are both researched. Simulation results show that there are optimum values of N, a and L for the lowest Pth. When a=50μm, L=9cm, N=1.8∗1020cm-3, R1s=1, R2s=0.75, the lowest threshold pump power Pth of the GG-IAG fiber laser is about 11.95W, the results of the work may be helpful for the later experiments. © 2016 The Authors, published by EDP Sciences.
  Accession Number: 20164302931451
• Record 156 of
  
  Title:In Situ Surface Assembly Derived Ultralow Refractive Index MgF2-SiO2 Hybrid Film for Tri-Layer Broadband Antireflective Coating
  
  Author(s):Cui, Xinmin(1); Ding, Ruimin(1); Wang, Mengchao(1); Zhang, Cong(1); Zhang, Ce(1); Zhang, Jing(1); Xu, Yao(2)
  Source: Advanced Optical Materials  Volume: 4  Issue: 5  DOI: 10.1002/adom.201500595  Published: May 1, 2016  
  Abstract:For the broadband antireflective (AR) coating working in specific wavelengths, the precise control over refractive index and film thickness of each layer is critical to guarantee the peak position locating at the targeted wavelengths. In this paper, a simple sol-gel procedure without post-treatment is used to prepare MgF2-SiO2 hybrid coating with tunable refractive index for the fabrication of tri-layer tri-wavelength broadband AR coating. The MgF2-SiO2 coating with ultralow refractive index of 1.12 is realized through in situ surface assembly of negatively charged silanol groups on vesicle-like MgF2 particles to obtain porous crosslinking structure. The electrostatic attraction between the negatively charged silanol groups and positively charged MgF2 colloidal particles plays a key role. Furthermore, the MgF2-SiO2 coating with a wide range of refractive index between 1.20 and 1.44 is achieved by adjusting the addition amount of acid-catalyzed silica sol into the vesicle-like MgF2 sol. According to the theoretical design, a tri-layer broadband AR coating with refractive index model of 1.12/1.26/1.36 is prepared, which can enhance the transmittance of quartz substrate to near 100% simultaneously at 351, 527, and 1053 nm. The MgF2-SiO2 coatings with ultralow refractive index of 1.12 and tunable refractive index of 1.20-1.44 are prepared by a facile sol-gel procedure without post-treatment. Then, a tri-layer broadband AR coating with refractive index model of 1.12/1.26/1.36 is realized with excellent transmittance of nearly 100% simultaneously at 351, 527, and 1053 nm. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  Accession Number: 20160601905406