2017

• Record 193 of
  
  Title:Fabrication of microtapered/helical long-period fiber gratings with a CO2 laser fusion splicer
  
  Author(s):Ren, Kaili(1,2,3); Ren, Liyong(1); Kong, Xudong(1,3); Liang, Jian(1); Wu, Zhaoxin(3)
  Source: ICOCN 2017 - 16th International Conference on Optical Communications and Networks  Volume: 2017-January  Issue:   DOI: 10.1109/ICOCN.2017.8121554  Published: November 27, 2017  
  Abstract:A new scheme for fabricating microtapered long-period fiber gratings (LPFGs) and helical LPFGs is proposed and demonstrated successfully by periodically tapering and twisting a standard single-mode fiber, respectively, using a CO2 laser fusion splicer as heater. In comparison to previous fabrication methods, our scheme can significantly improve the quality of the microtapered and helical LPFGs. Considering the simple and flexible fabrication process as well as the high quality of fabricated gratings, we believe that this may offer a simpler and alternative choice to current filters or sensing applications. © 2017 IEEE.
  Accession Number: 20181104903368
• Record 194 of
  
  Title:Optimization of micro channel heat sinks for high-power 9xx-nm laser diodes
  
  Author(s):Zhang, Hongyou(1); Liang, Xuejie(1); Cai, Wanshao(1); Zah, Chungen(1); Liu, Xingsheng(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 10098  Issue:   DOI: 10.1117/12.2256112  Published: 2017  
  Abstract:High power laser diodes have found a wide range of industrial, space, medical applications, characterized by high conversion efficiency, small size, light weight and a long lifetime. In this investigation, high power 940 nm laser bars were mounted on optimized micro-channel heat sinks (MCC) using AuSn/CuW and In Soldering schemes. The optimized MCC cooler has decreased pressure drop and increased heat-sinking capability. The improvements in thermal and strain characteristics will be reported through wavelength, thermal rollover, spatial spectrum, SMILE, and polarization. © 2017 SPIE.
  Accession Number: 20172003664451
• Record 195 of
  
  Title:Femtowatt incoherent image conversion from mid-infrared light to near-infrared light
  
  Author(s):Huang, Nan(1); Liu, Hongjun(1,2); Wang, Zhaolu(1); Han, Jing(1); Zhang, Shuan(1)
  Source: Laser Physics  Volume: 27  Issue: 3  DOI: 10.1088/1555-6611/aa57db  Published: March 2017  
  Abstract:We report on the experimental conversion imaging of an incoherent continuous-wave dim source from mid-infrared light to near-infrared light with a lowest input power of 31 femtowatt (fW). Incoherent mid-infrared images of light emission from a heat lamp bulb with an adjustable power supply at window wavelengths ranging from 2.9 μm to 3.5 μm are used for upconversion. The sum-frequency generation is realized in a laser cavity with the resonant wavelength of 1064 nm pumped by an LD at 806 nm built around a periodically poled lithium niobate (PPLN) crystal. The converted infrared image in the wavelength range ∼785 nm with a resolution of about 120 × 70 is low-noise detected using a silicon-based camera. By optimizing the system parameters, the upconversion quantum efficiency is predicted to be 28% for correctly polarized, on-axis and phase-matching light. © 2017 Astro Ltd.
  Accession Number: 20170803363283
• Record 196 of
  
  Title:Crystal structure and optical properties of a neodymium trifluoroacetate complex for liquid laser
  
  Author(s):She, Jiangbo(1); Nie, Rongzhi(1); Sun, Xin(2); Peng, Bo(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 10256  Issue:   DOI: 10.1117/12.2260699  Published: 2017  
  Abstract:The neodymium trifluoroacetate complex was synthesized and characterized by single-crystal X-ray diffraction, elemental and TG analysis, FT-IR spectra, and PL spectra. The optical properties of the liquid medium were studied. From the absorption and luminescence spectra, the Judd-Ofelt parameters of the Nd(CF3COO)3 dissovled in phosphorus oxychloride were obtained. Based on the crystal structure, the effects of crystal field and bond valance properties on three intensity parameters Ωt(t=2,4,6) and emission cross-section were analyzed in detail. The emission cross-section of 4F3/2→4I11/2 fluorescence transition (3.63×10-20cm2) of the new neodymium compound was higher than those of other Nd(III) complexes and even comparable with some laser glasses. © 2017 SPIE.
  Accession Number: 20171703607586
• Record 197 of
  
  Title:Design, fabrication, and optical gain performance of the gain-guided and index-antiguided Nd3+-doped phosphate glass fiber
  
  Author(s):Shen, Xiao(1,2); Zhang, Liaolin(1); Ding, Jianyong(3); Wei, Wei(1)
  Source: Journal of the Optical Society of America B: Optical Physics  Volume: 34  Issue: 5  DOI: 10.1364/JOSAB.34.000998  Published: May 1, 2017  
  Abstract:Design, fabrication, and optical gain performance of the gain-guided and index-antiguided (GG-IAG) fiber are studied systematically in this work. The main parameters of the GG-IAG fiber, i.e., a, Δn, g, and ν, are designed by single-mode operation theories, followed by a detailed study of the fabrication of the GG-IAG fiber, including preform design and fabrication, fiber-drawing conditions, and so on. GG-IAG fibers with different core diameters (100-380 μm) are obtained and their corresponding performance is measured. In order to verify whether the parameters of the fabricated GG-IAG fiber meet the theoretical design, the laser amplifier experiments of the GG-IAG fiber and the fabricated gain-guided and index-guided (GG-IG) fiber are both demonstrated. The experimental results show that the net optical gain coefficient of the GG-IG fiber is the sum of the net optical gain coefficient and the leakage loss coefficient of the GG-IAG fiber, which indicates that the fabricated GG-IAG fiber parameters and performance are consistent with the theoretical design. This work should help further exploration of the GG-IAG fiber. © 2017 Optical Society of America.
  Accession Number: 20171903639625
• Record 198 of
  
  Title:Hyperspectral Image Superresolution by Transfer Learning
  
  Author(s):Yuan, Yuan(1); Zheng, Xiangtao(1); Lu, Xiaoqiang(1)
  Source: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing  Volume: 10  Issue: 5  DOI: 10.1109/JSTARS.2017.2655112  Published: May 2017  
  Abstract:Hyperspectral image superresolution is a highly attractive topic in computer vision and has attracted many researchers' attention. However, nearly all the existing methods assume that multiple observations of the same scene are required with the observed low-resolution hyperspectral image. This limits the application of superresolution. In this paper, we propose a new framework to enhance the resolution of hyperspectral images by exploiting the knowledge from natural images: The relationship between low/high-resolution images is the same as that between low/high-resolution hyperspectral images. In the proposed framework, the mapping between low- A nd high-resolution images can be learned by deep convolutional neural network and be transferred to hyperspectral image by borrowing the idea of transfer learning. In addition, to study the spectral characteristic between low- A nd high-resolution hyperspectral image, collaborative nonnegative matrix factorization (CNMF) is proposed to enforce collaborations between the low- A nd high-resolution hyperspectral images, which encourages the estimated solution to extract the same endmembers with low-resolution hyperspectral image. The experimental results on ground based and remote sensing data suggest that the proposed method achieves comparable performance without requiring any auxiliary images of the same scene. © 2016 IEEE.
  Accession Number: 20170803365225
• Record 199 of
  
  Title:Temporal imaging based on four-wave mixing in slow-light photonic crystal waveguide
  
  Author(s):Zhou, Mingyang(1); Liu, Hongjun(1,2); Wang, Zhaolu(1); Huang, Nan(1); Han, Jing(1)
  Source: Journal of Optics (United Kingdom)  Volume: 19  Issue: 12  DOI: 10.1088/2040-8986/aa9138  Published: December 2017  
  Abstract:We have proposed a temporal imaging system based on four-wave mixing (FWM) in the dispersion engineered slow-light photonic crystal waveguide (PCW). Dispersion relations of the modified PCW are calculated through the 3D plane wave expansion method. Time lens is demonstrated by solving the couple-mode equations describing the FWM process inside the PCW directly. Intensity and phase evolutions of the signal, pump and idler waves during the FWM process are calculated to investigate temporal imaging. Meanwhile, temporal magnifications with different magnification factors are realized by tuning the total dispersion of the input signals. Furthermore, influences of dispersion and free-carrier effects inside PCW on the temporal imaging performance are analyzed. The simulation results show the capability to realize temporal imaging system based on the FWM process in slow-light engineered PCW. © 2017 IOP Publishing Ltd.
  Accession Number: 20180104607021
• Record 200 of
  
  Title:Learning Discriminative Binary Codes for Large-scale Cross-modal Retrieval
  
  Author(s):Xu, Xing(1); Shen, Fumin(1); Yang, Yang(1); Shen, Heng Tao(1); Li, Xuelong(2)
  Source: IEEE Transactions on Image Processing  Volume: 26  Issue: 5  DOI: 10.1109/TIP.2017.2676345  Published: May 2017  
  Abstract:Hashing based methods have attracted considerable attention for efficient cross-modal retrieval on large-scale multimedia data. The core problem of cross-modal hashing is how to learn compact binary codes that construct the underlying correlations between heterogeneous features from different modalities. A majority of recent approaches aim at learning hash functions to preserve the pairwise similarities defined by given class labels. However, these methods fail to explicitly explore the discriminative property of class labels during hash function learning. In addition, they usually discard the discrete constraints imposed on the to-be-learned binary codes, and compromise to solve a relaxed problem with quantization to obtain the approximate binary solution. Therefore, the binary codes generated by these methods are suboptimal and less discriminative to different classes. To overcome these drawbacks, we propose a novel cross-modal hashing method, termed discrete cross-modal hashing (DCH), which directly learns discriminative binary codes while retaining the discrete constraints. Specifically, DCH learns modality-specific hash functions for generating unified binary codes, and these binary codes are viewed as representative features for discriminative classification with class labels. An effective discrete optimization algorithm is developed for DCH to jointly learn the modality-specific hash function and the unified binary codes. Extensive experiments on three benchmark data sets highlight the superiority of DCH under various cross-modal scenarios and show its state-of-the-art performance. © 2016 IEEE.
  Accession Number: 20171703606835
• Record 201 of
  
  Title:Nanosecond pulse signals restoration via stochastic resonance in the Fabry-Perot cavity with graphene
  
  Author(s):Chang, Zheng(1,3); Liu, Hongjun(1,2); Huang, Nan(1); Wang, Zhaolu(1); Han, Jing(1)
  Source: EPJ Applied Physics  Volume: 79  Issue: 2  DOI: 10.1051/epjap/2017170145  Published: August 1, 2017  
  Abstract:We investigate a technology for reconstructing nanosecond pulse noise hidden signals via stochastic resonance, which is based on optical bistability in the Fabry-Perot (F-P) cavity with graphene. The bistable properties are analyzed with different initial wavelengths and Fermi energies. The system is tunable and the bistable behavior of the output intensity can be accurately controlled to obtain a cross-correlation gain larger than 10 in a wide range of input signal-to-noise (SNR) ratio from 1:8 to 1:45. Meanwhile, the distortion of the output signal and the pulse tailing caused by the phase delay can be reduced to a negligible level. This work provides a potential method for detecting low-level or hidden pulse signals in various communication fields. © 2017 EDP Sciences.
  Accession Number: 20173003982915
• Record 202 of
  
  Title:Enhancement of quantum-enhanced LADAR receiver in nonideal phase-sensitive amplification
  
  Author(s):Zhang, Shuan(1,2); Liu, Hongjun(1,3); Huang, Nan(1); Wang, Zhaolu(1); Han, Jing(1)
  Source: EPJ Applied Physics  Volume: 79  Issue: 2  DOI: 10.1051/epjap/2017170113  Published: August 1, 2017  
  Abstract:The phase-sensitive amplification (PSA) with an injected squeezed vacuum field is theoretically investigated in quantum-enhanced laser detection and ranging (LADAR) receiver. The theoretical model of the amplified process is derived to investigate the quantum fluctuations in detail. A new method of mitigating the unflat gain of nonideal PSA is proposed by adjusting the squeezed angle of the squeezed vacuum field. The simulation results indicate that signal-noise ratio (SNR) of system can be efficiently improved and close to the ideal case by this method. This research will provide an important potential in the applications of quantum-enhanced LADAR receiver. © 2017 EDP Sciences.
  Accession Number: 20172903953665
• Record 203 of
  
  Title:A Tunable Dispersion Waveguide Based on Graphene-Silicon Lateral Slot Geometric Structure
  
  Author(s):Li, Zhen(1); Liu, Hongjun(1,2); Huang, Nan(1); Wang, Zhaolu(1); Han, Jing(1)
  Source: IEEE Photonics Journal  Volume: 9  Issue: 1  DOI: 10.1109/JPHOT.2017.2654447  Published: February 2017  
  Abstract:The dispersion profiles of a hybrid graphene-silicon (HyGS) slot waveguide with trilayers of graphene are investigated in this paper. By tuning the bias voltage on graphene layer, the zero dispersion wavelengths (ZDW) of HyGS slot waveguide can be tailored dynamically and effectively. With small disturbed voltage (6 V), a large ZDW tuning amount (200 nm) is achieved, without the need for changing the geometric structure of the waveguide, which has been verified with numerical simulation. Moreover, the dispersion curve of HyGS slot waveguide is flat enough (group velocity dispersion slope less than 2 ps/nm2·km), in the vicinity of ZDW. This waveguide is highly beneficial to such applications as integrated optics and graphene-related active optical devices. © 2016 IEEE.
  Accession Number: 20171103440249
• Record 204 of
  
  Title:Ultrafast pulse generation with black phosphorus solution saturable absorber
  
  Author(s):Li, Lu(1,2); Wang, Yonggang(1); Wang, Xi(3)
  Source: Laser Physics  Volume: 27  Issue: 8  DOI: 10.1088/1555-6611/aa7486  Published: August 2017  
  Abstract:The study presents the mode-locked Er-doped fiber (EDF) laser with a black phosphorus (BP) solution saturable absorber (SSA). The saturable absorber (SA) is fabricated based on a D-shaped fiber (DF) embedded in BP nanosheets N-Methylpyrrolidone solution. Such a BP solution method has the virtues of good antioxidant capacity, high heat dissipation and high damage threshold. This kind of SA shows a modulation depth of 7.75% and a nonsaturable loss of 10%. By employing the EDF-BP SSA, a repetition rate of 15.2 MHz mode-locked fiber laser is achieved. The pulse duration is 580 fs and the signal-to-noise ratio is 65 dB. The results indicate that the DF-BP solution can work as a potential SA for ultrafast nonlinear optics. © 2017 Astro Ltd.
  Accession Number: 20173204017073