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2019

• Record 517 of
  
  Title:L-band mode-locked femtosecond fiber laser with gigahertz repetition rate
  
  Author(s):Song, Jiazheng(1,2); Liu, Yuanshan(1,3); Zhang, Jianguo(1,4)
  Source: Applied Optics  Volume: 58  Issue: 27  DOI: 10.1364/AO.58.007577  Published: September 20, 2019  
  Abstract:We demonstrate an L-band passively mode-locked femtosecond fiber laser with a fundamental repetition rate of 1.013 GHz based on a semiconductor saturable absorber mirror. Compared with other reported L-band fiber lasers that use overlong Er-doped fiber, the laser here consists of 10 cm heavily doped fiber to increase the fundamental pulse repetition rate to gigahertz level. An output ratio as low as 0.2% is used to make the central wavelength up to 1.6 μm. The laser operates at the soliton regime with a 3 dB spectral bandwidth of 13.6 nm and a pulse duration of 229 fs. ? 2019 Optical Society of America.
  Accession Number: 20193907463027
• Record 518 of
  
  Title:High temperature resistant ultra-short DBR Yb-doped fiber laser
  
  Author(s):Wang, Hushan(1,3); Xiong, Songsong(2); Song, Jiazheng(1,3); Zhao, Fengyan(1,3); Yan, Zhijun(4); Hong, Xiaohu(1); Zhang, Ting(1); Zhang, Wei(1); Zhou, Kaiming(1); Li, Cheng(2); Wang, Yishan(1)
  Source: Applied Optics  Volume: 58  Issue: 16  DOI: 10.1364/AO.58.004474  Published: June 1, 2019  
  Abstract:We present a distributed Bragg reflector (DBR) Yb-doped fiber laser based on a pair of type IA fiber Bragg gratings (FBGs). The high temperature resistant gratings are fabricated in high absorption hydrogen loaded Yb-doped silica fiber by use of a 244 nm argon laser and phase mask method. The DBR laser, with only 10 mm cavity length, exhibits high signal-noise ratio (SNR) of over 50 dB and can survive at 450°C in a long term with stable output power and central wavelength. Besides, the laser has a relatively low temperature sensitivity of 8.9 pm/°C, which contributes to cross-sensitization of stress and temperature. ? 2019 Optical Society of America
  Accession Number: 20192307009624
• Record 519 of
  
  Title:Purely Kerr nonlinear model admitting flat-top solitons
  
  Author(s):Zeng, Liangwei(1,2); Zeng, Jianhua(1,2); Kartashov, Yaroslav V.(3); Malomed, Boris A.(4,5)
  Source: Optics Letters  Volume: 44  Issue: 5  DOI: 10.1364/OL.44.001206  Published: March 1, 2019  
  Abstract:We elaborate one- and two-dimensional (1D and 2D) models of media with self-repulsive cubic nonlinearity, whose local strength is subject to spatial modulation that admits the existence of flat-top solitons of various types, including fundamental ones, 1D multipoles, and 2D vortices. Previously, solitons of this type were only produced by models with competing nonlinearities. The present setting may be implemented in optics and Bose–Einstein condensates. The 1D version gives rise to an exact analytical solution for stable flat-top solitons, and generic families may be predicted by means of the Thomas–Fermi approximation. Stability of the obtained flat-top solitons is analyzed by means of the linear-stability analysis and direct simulations. Fundamental solitons and 1D multipoles with k 1 and 2 nodes, as well as vortices with winding number m 1, are completely stable. For multipoles with k ≥ 3 and vortices with m ≥ 2, alternating stripes of stability and instability are identified in their parameter spaces. ? 2019 Optical Society of America
  Accession Number: 20191006584447
• Record 520 of
  
  Title:Chip-integrated metasurface for versatile and multi-wavelength control of light couplings with independent phase and arbitrary polarization
  
  Author(s):Meng, Yuan(1,2); Hu, Futai(1); Liu, Zhoutian(1); Xie, Peng(2,3); Shen, Yijie(1); Xiao, Qirong(1); Fu, Xing(1); Bae, Sang-Hoon(2); Gong, Mali(1,4)
  Source: Optics Express  Volume: 27  Issue: 12  DOI: 10.1364/OE.27.016425  Published: June 10, 2019  
  Abstract:While metasurfaces are now widely considered in free-space optics, their potential for coupling and tailoring guided waves is not fully explored. Here we transfer the Jones matrix method to target versatile on-chip coupling using metasurface-patterned photonic waveguides around the telecommunication wavelength of 1.55 μm, which can accommodate both propagation and Pancharatnam-Berry phase metasurfaces for guided waves. One can either encode two arbitrary and independent phase profiles to any pair of orthogonal polarizations or deploy complete control over both the phase and polarization of coupled modes. A set of design scenarios synergizing silicon nanoantennas and low-loss silicon-nitride waveguides are proposed, including directional couplers with mode-selectivity and polarization splitters with directionality ranging from 10 to 20 dB. Furthermore, our optimization method can be further extended to cover multiple working wavelengths. Exemplary on-chip color routers are also numerically demonstrated. This chip-integrated metasurface platform further translates the concept of a metasurface into photonic integrated circuits, serving as a positive paradigm for versatile and complete control over waveguide optical signals and motivating chip-scale applications such as polarization/wavelength demultiplexers, optical switches, and multifunctional mode converters. ? 2019 Optical Society of America.
  Accession Number: 20192407047822
• Record 521 of
  
  Title:Adaptive visual multi-object tracker based on multi-bernoulli filter and region feature covariance
  
  Author(s):Zhang, Guangnan(1,2); Yang, Jinlong(3); Wang, Weixing(1); Qiu, S.H.I.(4); Tang, Y.U.(3)
  Source: International Journal of Innovative Computing, Information and Control  Volume: 15  Issue: 3  DOI: 10.24507/ijicic.15.03.1131  Published: June 2019  
  Abstract:Multi-Bernoulli (MB) filter has been demonstrated as a promising algorithm for tracking multiple point targets with unknown and time-varying number of targets. However, for the visual multi-object tracking (VMOT), the tracking accuracy will decrease severely due to the problems of closely-spaced object, occlusion and scale variation. To solve these problems, an adaptive VMOT algorithm based on the framework of the MB filter is proposed in this paper. First, the region feature covariance (RFC) is employed to enhance the ability of anti-interference, and then the discrimination strategy for the closely-spaced objects and the adaptive estimate strategy for scale variation are developed according to the constraints of tracking boxes. Finally, the particle labeling technique is introduced to identify the track of each target. Experimental results validate superior performance of the proposed algorithm over the traditional MB-based VMOT algorithm in scenarios that include occlusion, background clutter, scale changes, and closely-spaced objects. ? 2019, ICIC International. All rights reserved.
  Accession Number: 20192407032636
• Record 522 of
  
  Title:Excessively tilted fiber grating-based vector magnetometer
  
  Author(s):Lu, Tean(1); Sun, Yuezhen(1); Moreno, Yarien(1,4); Sun, Qizhen(1); Zhou, Kaiming(2,3); Wang, Hushan(3); Yan, Zhijun(1,2,3); Liu, Deming(1); Zhang, Lin(2)
  Source: Optics Letters  Volume: 44  Issue: 10  DOI: 10.1364/OL.44.002494  Published: May 15, 2019  
  Abstract:A compact optic-fiber vector magnetometer is proposed and experimentally demonstrated, which is based on an excessively tilted fiber grating (Ex-TFG) assistant with the magnetic fluid (MF). Without any complicated processing, the cladding mode resonances of the bare Ex-TFG packaged by the MF show high sensitivity to slight perturbations by the magnetic field. Due to the excellent magneto-optical properties of the MF and the azimuth-dependent refractive index sensitivity of the Ex-TFG, such a magnetometer can achieve the magnetic field intensity sensitivity of 2.45 nm/mT and the orientation sensitivity of 0.41 nm/ deg. In addition, based on the spectral interrogation, the detection limit of the magnetic field intensity could reach around 8.1 μT at the minimum wavelength measurement accuracy of 0.02 nm. ? 2019 Optical Society of America
  Accession Number: 20192106968768
• Record 523 of
  
  Title:Artificial compound eye-tipped optical fiber for wide field illumination
  
  Author(s):Liu, Feng(1,3); Yang, Qing(2,3); Bian, Hao(1,3); Zhang, Fan(1,3); Hou, Xun(1); Kong, Depeng(4); Chen, Feng(1,3)
  Source: Optics Letters  Volume: 44  Issue: 24  DOI: 10.1364/OL.44.005961  Published: December 15, 2019  
  Abstract:In this Letter, we present a novel, to the best of our knowledge, component with beam delivering and wide field beam homogenizing functions by grafting an artificial compound eye (ACE) micro-structure onto the polymer optical fiber (POF) end face. The 3D ACE mold is fabricated by femtosecond laser-assisted micro machining, and the ACE micro-structure is transferred onto the end face through high accuracy nano-imprinting. The resultant POF end face integrates over 400 spherical micro-lenses, enabling a 40% enhancement in both the acceptance angle and the effective numerical aperture. Meanwhile, the integrated ommatidia array serves as an outstanding beam homogenizer, shaping the output beam into quasi flat-top distribution, which demonstrates promise in wide field homogeneous illumination, by reflection and transmission imaging experiments in both visible and near infrared bands. ? 2019 Optical Society of America.
  Accession Number: 20195107853889
• Record 524 of
  
  Title:A chiral long-period grating fabrication method based on axis-offset rotating optical fiber
  
  Author(s):Kong, Xudong(1,3); Ren, Liyong(1,2); Liang, Jian(1); Ren, Kaili(4); Ju, Haijuan(1,3); Xu, Yiping(5); Xu, Chengfang(1,3)
  Source: Optical and Quantum Electronics  Volume: 51  Issue: 4  DOI: 10.1007/s11082-019-1841-9  Published: April 1, 2019  
  Abstract:We propose a method to fabricate chiral long-period grating (CLPG) by rotating the standard single mode fiber which is fixed on two fiber holders but with an axis-offset. We show that, compared with traditional fabrication methods, this axis-offset method is capable of obtaining identical resonance wavelengths of the CLPGs for the same grating period. We investigate the performance of CLPGs by detecting the interference between the light emerging from CLPGs and a reference light. The achieved forklike and spiral interference patterns both confirm the generation of ± 1-order optical vortex through CLPG. Experimental results indicate that high-quality CLPGs can be easily and repeatedly fabricated by this method. ? 2019, Springer Science+Business Media, LLC, part of Springer Nature.
  Accession Number: 20191606798415
• Record 525 of
  
  Title:Ultrashort bessel beam photoinscription of bragg grating waveguides and their application as temperature sensors
  
  Author(s):Zhang, Guodong(1,2); Cheng, Guanghua(1,3); Bhuyan, Manoj K.(1,4,5); D’Amico, Ciro(1); Wang, Yishan(2); Stoian, Razvan(1)
  Source: Photonics Research  Volume: 7  Issue: 7  DOI: 10.1364/PRJ.7.000806  Published: July 2019  
  Abstract:Ultrashort pulsed Bessel beams with intrinsic nondiffractive character and potential strong excitation confinement down to 100 nm can show a series of advantages over Gaussian beams in fabricating efficient Bragg grating waveguides (BGWs). In this work, we focus on parameter management for the inscription of efficient BGWs using the point-by-point method employing Bessel beams. Due to their high aspect ratio, the resulting one-dimensional void-like structures can section the waveguides and interact efficiently with the optical modes. Effective first-order BGWs with low birefringence can then be fabricated in bulk fused silica. By controlling the size and the relative location of grating voids via the Bessel pulse energy and scan velocities, the resonant behaviors of BGWs can be well regulated. A high value of 34 dB for 8 mm length is achieved. A simple predictive model for BGWs is proposed for analyzing the influences of processing parameters on the performance of BGWs. The technique permits multiplexing several gratings in the same waveguide. Up to eight grating traces were straightforwardly inscribed into the waveguide in a parallel-serial combined mode, forming the multiplex BGWs. As an application, the multiplex BGW sensor with two resonant peaks is proposed and fabricated for improving the reliability of temperature detection. ? 2019 Chinese Laser Press.
  Accession Number: 20193407333797
• Record 526 of
  
  Title:Microfiber interferometer integrated with Au nanorods for an all-fiber phase shifter and switch
  
  Author(s):Yang, Xinghua(1); Long, Qunlong(1); Liu, Zhihai(1,3); Zhang, Yu(1); Yang, Jun(1); Kong, Depeng(2); Yuan, Libo(1,4); Oh, Kyunghwan(5)
  Source: Optics Letters  Volume: 44  Issue: 5  DOI: 10.1364/OL.44.001092  Published: March 1, 2019  
  Abstract:All-fiber integrated phase shifters and optical switches have important applications in photonic devices, such as optical controlling, optical fiber sensing, and signal processing. In this Letter, for the first time to the best of our knowledge, we integrated the photothermal effect of a nanomaterial based on gold nanorods (GNRs) and a microfiber interferometer to realize a compact all-optical fiber phase shifter. GNRs surrounding the microfiber were excited by near-infrared light via the evanescent interaction, subsequently releasing the heat through the photothermal effect. Then, the refractive index around the microfiber was varied to shift the interference dips in a reversible manner. Experimentally, a spectral shift efficiency of 0.16 nm/mW near the wavelength of 1550 nm was obtained using an excitation laser at the wavelength of 808 nm. The device also provided an all-optical switching with the modulation depth of 76.4%. The proposed GNR-based all-fiber device can provide high potentials in all-optical signal control applications. ? 2019 Optical Society of America.
  Accession Number: 20191006584451
• Record 527 of
  
  Title:Optical vortex shaping via a phase jump factor
  
  Author(s):Ma, Haixiang(1); Li, Xinzhong(1); Zhang, Hao(1); Tang, Jie(2); Li, Hehe(1); Tang, Miaomiao(1); Wang, Jingge(1); Cai, Yangjian(3,4)
  Source: Optics Letters  Volume: 44  Issue: 6  DOI: 10.1364/OL.44.001379  Published: 2019  
  Abstract:Topological charge (TC) of an optical vortex (OV) is a crucial parameter. We propose two factors, namely, the phase jump factor and the phase gradient factor, to replace the parameter of TC through unwrapping the TC definition integral. Based on these two factors, we report on a novel OV, referred to as the remainder-phase optical vortex (ROV). The properties of the ROV are studied in depth by adjusting these two factors. Results show that the phase gradient factor determines the total orbital angular momentum (OAM), whereas the phase jump factor decides the number of split unit vortices and reshapes the structure of the OAM distribution. This work provides a novel OV with controllable OAM distribution, which will open up new applications such as particle manipulation, beam shaping, and micro-fabrication. ? 2019 Optical Society of America.
  Accession Number: 20191206671512
• Record 528 of
  
  Title:Tunable photonic RF bandpass filters based on an 80 channel kerr micro-comb source
  
  Author(s):Tan, Mengxi(1); Xu, Xingyuan(1); Wu, Jiayang(1); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5,6,7); Mitchell, Arnan(2); Moss, David J.(1)
  Source: Optics InfoBase Conference Papers  Volume: Part F129-CLEO_SI 2019  Issue:   DOI: 10.1364/CLEO_SI.2019.SF2N.4  Published: 2019  
  Abstract:We demonstrate a tunable photonic RF bandpass filter based on a Kerr micro-comb source providing 80 taps in the C-band. We achieve a widely tunable centre frequency (0.05FSRRF ~ 0.40FSRRF) and 3-dB bandwidth (0.5 ~ 4.6 GHz). ? 2019 The Author(s)
  Accession Number: 20192707136999