2022

• Record 349 of
  
  Title:Orbital angular momentum in optical manipulations
  
  Author(s):Li, Manman(1); Yan, Shaohui(1); Zhang, Yanan(1); Zhou, Yuan(1); Yao, Baoli(1,2)
  Source: Journal of Optics (United Kingdom)  Volume: 24  Issue: 11  DOI: 10.1088/2040-8986/ac9192  Published: November 2022  
  Abstract:Since Allen et al recognized that light beams possessing a helical phase structure can carry orbital angular momentum (OAM), OAM of light has witnessed groundbreaking developments and has founded tremendous applications in a broad range of fields. In this article, beginning with a general introduction to OAM, basic theories, and computational approaches, we provide an overview on recent advances in optical manipulation with OAM. Owing to the distinct characteristics of OAM beams feature, i.e. helical wave front, doughnut intensity profile and certain OAM per photon. Optical manipulation using OAM has demonstrated innovative landscapes, realized the manipulation of particles with different functions ranging from optical spanner, manipulating of low-refractive-index particles, optical sorting and guiding, up to optical spin-orbit interaction and chiral discrimination. This review will be helpful for understanding the mechanisms behind light-matter interaction. © 2022 IOP Publishing Ltd.
  Accession Number: 20224212975942
• Record 350 of
  
  Title:A Compact 2D Polarization Splitting Grating Coupler with Lens Tapers
  
  Author(s):Xue, Jintao(1); Wang, Binhao(1)
  Source: Progress in Electromagnetics Research Symposium  Volume: 2022-April  Issue:   DOI: 10.1109/PIERS55526.2022.9792658  Published: 2022  
  Abstract:We present a highly-efficient and ultra-compact polarization splitting grating coupler based on apodized designs of blazed gratings and lens tapers. Within the overall footprint 60 times 60 mu mathrm{m}{2}, the simulated transmission of -2.2 dB at 1308nm and the crosstalk between two polarizations of -16 dB are achieved. © 2022 IEEE.
  Accession Number: 20222612274702
• Record 351 of
  
  Title:A porous core Zeonex THz fiber with low loss and small dispersion
  
  Author(s):Mei, Sen(1,2); Kong, Depeng(1); Mu, Qiyuan(1,2); Li, Wenlong(1,2,3); He, Zhengquan(1); Wang, Lili(1); Zhang, Yani(4)
  Source: Optical Fiber Technology  Volume: 69  Issue:   DOI: 10.1016/j.yofte.2022.102834  Published: March 2022  
  Abstract:A fabricated microstructured polymer optical fiber (MPOF), with porous core and porous cladding consisting of a hexagonal array of circular air-holes, is experimentally investigated via a terahertz (THz) time-domain spectroscopy (TDS) setup. The fiber features a low propagation loss ranged from 0.0180 to 0.0345 cm−1, in the frequency regime of 0.3–0.5 THz with diameter of 3 mm. Meanwhile, the dispersion and fabrication deformation are also discussed. Experimental results show there is a flat and near-zero dispersion band in the range of 0.39 to 0.45 THz with a value of −0.285 ± 0.02 ps/THz/cm The simulation and experimental results of transmission loss and dispersion are in good agreement within 0.3–0.5 THz. There are a few deviations regarding air porosity between theoretical and actual structure, and the absolute variation of air hole fraction in core and cladding is 0.485% and 1.657%, respectively. The proposed MPOF is potentially useful for efficient and convenient transmission of broadband THz radiation. © 2022 Elsevier Inc.
  Accession Number: 20220711620666
• Record 352 of
  
  Title:Numerical Study of Broadband Wavelength Conversion Based on InP/In1-xGaxAsyP1-y Strip-loaded Waveguide
  
  Author(s):Wen, Jin(1,2); He, Chenyao(1); Qin, Weijun(1); Sun, Wei(1); Liang, Bozhi(1); Xiong, Keyu(1); Zhang, Hui(1); Wu, Zhengwei(1); Yu, Huimin(1); Wang, Qian(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 51  Issue: 10  DOI: 10.3788/gzxb20225110.1019003  Published: October 2022  
  Abstract:In recent years， nonlinear integrated optical devices have shown great potential in all-optical signal processing， and a lot of research work has been done on them. The nonlinear integrated optical devices usually use silicon， Ⅲ-Ⅴ， chalcogenide glass and other materials platform. Silicon has very sophisticated low-cost manufacturing platforms， but silicon is an indirect band-gap list of semiconductor materials with very low luminous efficiency， and silicon needs to be integrated with other materials， for example， the integration of Ⅲ-Ⅴ lasers and amplifiers on a silicon substrate to achieve integrated optical path， which makes the integrated optical path complex and expensive， and has compatibility problems. As2Se3 chalcogenide glasses stand out among many materials because of their low linear and nonlinear loss， but their refractive index can not be adjusted within a certain range， which is not conducive to the flexibility of all-optical signal processing. The As2Se3 chalcogenide glass platform is not compatible with the Complementary Metal-oxide Semiconductor （COMS） process， and the fabrication process is complex. Various ternary and quaternary Ⅲ-Ⅴ compounds with different bandgap wavelengths can form a group of nonlinear photonic materials that can cover the whole spectrum window from ultraviolet to infrared. Ⅲ-Ⅴmaterials can improve the flexibility of custom-made integrated optical devices by changing the components of different materials， within a certain range. Ⅲ-Ⅴ semiconductor platforms enable active and passive integrated optical devices to be combined on the same material platform， which can be achieved by careful design and advanced manufacturing methods， for example， multilayer epitaxy and vertical coning. Ⅲ-Ⅴ semiconductor waveguides have high nonlinear coefficients， and minimal nonlinear absorption can be achieved by selecting the appropriate material composition and operating wavelength. Recent studies have shown that the carrier lifetime of Ⅲ-Ⅴ list of semiconductor materials can be reduced to 0.42 ps， which can reduce the nonlinear loss in the communication band and has the potential for efficient wavelength conversion. In this paper， an InP/In1-xGaxAsyP1-y strip-loaded waveguide is optimized and designed. The high efficiency broadband wavelength conversion is realized by zero phase mismatch of the waveguide from 1.53 μm to 1.59 μm. The waveguide has good nonlinear optics characteristics with a high Kerr coefficient of 2.2×10-17 m2/W. The wavelength conversion with 35 nm bandwidth and peak conversion efficiency of -26.7 dB is realized in the optimized waveguide structure. The influence of the doping coefficient y of In1-xGaxAsyP1-y on the wavelength conversion is discussed. The numerical results show that when the pump power and the pump wavelength are constant， with the doping coefficient y decreasing， the effect of the doping coefficient y on the wavelength conversion of In1-xGaxAsyP1-y on the wavelength conversion of In1-xGaxAsyP1-y is obvious， the conversion bandwidth is increased. In addition， the peak conversion efficiency of the waveguide is increased by increasing the pump power while the pump power is kept constant， and the band of the Idle Light is redshifted with the redshift of the pump wavelength. At the same time， the optimum length of InP/In1-xGaxAsyP1-y strip-loaded waveguide is 5 mm by analysis and numerical simulation. Wavelength converter based on InP/In1-xGaxAsyP1-y waveguide platform has important application value in optical communication， optical sensing and other fields. © 2022 Chinese Optical Society. All rights reserved.
  Accession Number: 20225213303318
• Record 353 of
  
  Title:Single underwater image restoration based on descattering and color correction
  
  Author(s):Ke, Ke(1,2,3); Zhang, Chunmin(1,2); Tang, Qian(1,2); He, Yifan(1,2); Yao, Baoli(3)
  Source: Optik  Volume: 259  Issue:   DOI: 10.1016/j.ijleo.2022.169009  Published: June 2022  
  Abstract:Underwater images typically exhibit color distortion and low contrast due to the absorption and scattering of the non-uniform medium during the propagation of light underwater. To address these problems, an effective underwater image restoration method is presented in this paper. Firstly, we adopted an adaptive dark channel prior that can be applied to underwater images with different color tones. Then, the local water light with strong robustness is obtained by utilizing maximum filtering and Gaussian low-pass filtering. Additionally, a linear relationship between blurred and clear images in the dark channel was introduced combining with the attenuation coefficient compensation to estimate the transmission of r, g and b channels. Ultimately, we designed a new adaptive color compensation method by taking into account the attenuation difference of the three color channels. Simulation and experimental results show that the proposed method can effectively improve the clarity and contrast of the image and eliminate color distortion. © 2022 Elsevier GmbH
  Accession Number: 20221511946265
• Record 354 of
  
  Title:A large dispersion-managed monolithic all-fiber chirped pulse amplification system for high-energy femtosecond laser generation
  
  Author(s):Li, Feng(1); Zhao, Wei(1); Wang, Yishan(1); Wang, Na(1); Li, Qianglong(1); Yang, Yang(1); Wen, Wenlong(1)
  Source: Optics and Laser Technology  Volume: 147  Issue:   DOI: 10.1016/j.optlastec.2021.107684  Published: March 2022  
  Abstract:A high energy monolithic all fiber chirped pulse amplification (CPA) system composed of fiber-silicate glass fiber is demonstrated in this work. In this compact system, the optical stretcher consists of two large dispersion chirped fiber Bragg gratings that offer a high stretch ratio to lower the nonlinearity that accumulates in the fiber amplifier. By employing high gain silicate glass fiber with a length of 20 cm as the main amplifier, an optimal balance of pulse energy and the B-integral is achieved. An amplified power of 42.6 W, corresponding to a pulse energy of 213 µJ, is obtained with an injection power of 100 mW. After compression, the laser pulses are compressed by a novel polarization-controlled double-pass configuration of a chirped volume Bragg grating (CVBG) to match the dispersion of the fiber stretcher. A total compression efficiency of 79.8% is obtained. The dispersion between the stretcher and the compressor is matched with the self-made temperature tuning device of the fiber grating. An optimized pulse width of 781 fs and a pulse energy of 170 µJ are obtained with the single-mode beam profile. To the best of our knowledge, this is the highest energy ever obtained with a single-mode beam profile for a spliced monolithic all-fiber CPA system. This compact high-energy fiber system will be useful in scientific research and industrial applications. © 2021 Elsevier Ltd
  Accession Number: 20214711184110
• Record 355 of
  
  Title:Complete and robust energy conversion by sum frequency generation based on Invariant Engineering
  
  Author(s):Zhang, Cong-Fu(1,3); Wang, Zhao-Lu(1); Liu, Hong-Jun(1,2)
  Source: arXiv  Volume:   Issue:   DOI: 10.48550/arXiv.2206.12207  Published: June 24, 2022  
  Abstract:We propose an analytical method to achieve complete energy conversion in sum frequency generation based on Lewis-Riesenfeld invariants theory. This technique, derived from a two-level atom transition in quantum mechanics, is more efficient and robust than conventional methods. In our scheme, the quasi-adiabatic single control parameter model is established, and the value of single control parameter is selected to make the initial eigenstate perfectly converted to the final eigenstate we need. Corresponds to the nonlinear frequency conversion process, the nonlinear crystal structure is designed with the inverse engineering of optimal control theory, which is robust against the perturbations in the coupling coefficient and phase mismatch, including pump intensity and crystal polarization period variations, and results in almost 100% conversion efficiency at any crystal length. It is demonstrated that the frequency conversion can be achieved in the wavelength range of 2.6 μm -3.6 μm with a spectral bandwidth of the conversion efficiency over 50% approaching to 400 nm when the crystal length L=1 mm. Copyright © 2022, The Authors. All rights reserved.
  Accession Number: 20220257031
• Record 356 of
  
  Title:Ultrafast Terahertz Characteristic Spectroscopy Based on Femtosecond Laser and Its Application（Invited）
  
  Author(s):Fan, Wenhui(1); Yan, Hui(1); Jiang, Xiaoqiang(1); Chen, Longchao(1); Zheng, Zhuanping(1); Liu, Jia(1); Li, Hui(1); Ding, Ling(1); Song, Chao(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 51  Issue: 7  DOI: 10.3788/gzxb20225107.0751403  Published: July 2022  
  Abstract:Terahertz（THz）waves（0.1 THz ~ 10 THz，1 THz = 1012 Hz）locate in the transitional region of the electromagnetic spectrum，between the classical electronics（radio，microwave and millimeter wave）and the photonics（infrared，visible，ultraviolet and x-ray）. As a kind of coherent measurement technology in THz frequency range，THz characteristic spectroscopy，with high sensitivity，rapidness and nondestructive testing as well as other unique advantages，has shown an attractive promising application prospect in detection，analysis and identification of biochemical molecules and materials. As the widely used broadband THz wave source，THz Photoconductive Antenna（THz-PCA）can emit broadband THz radiation. Therefore，as one of the promising THz emitters and detectors，THz-PCA has the advantages to overcome the defects confronted by other devices （e. g.，low operation frequency，strict working condition and bulk size）and these unique advantages have made THz-PCA become the most commonly utilized THz sources in THz Time-Domain Spectroscopy（THz-TDS）. Although a variety of THz-PCAs are commercially available and become indispensable in many practical applications currently， the insufficient radiation THz power still hinder the further development of THz technologies based on THz-PCA. In order to further promote the research interests of THz-PCA，the working mechanism and some new research progress，technical challenges in the process of practical application and strategies of THz-PCA have to be discussed and analyzed. The underlying physical mechanism of the transient response in THz-PCA emitter and detector are investigated，as well as the influence of several parameters including the power intensity of femtosecond pump laser，the laser pulse duration and the carrier lifetime of the substrate material，are also analyzed based on theoretical models，which provide the technical foundation for designing the efficient THz-PCA. Moreover，a plenty of valuable research schemes have been proposed to develop the THz technologies based on THz-PCA in the past decades，including photoconductive materials and structure design of THz-PCA. To be specific，the sub-picosecond carrier life time of photoconductor can be realized by creating a massive density of defects，dislocations and scattering centers in the substrate material. As for structure design of THz-PCA，the previous researches on THz-PCA was mainly focused on the saturation effect at high pump power and the large aperture dipoles，dipole arrays and interdigitated electrodes structures have been investigated during the early stage. In the recent years，as the quick development of micro-nano fabrication technologies，the THz-PCA incorporated with plasmonic nanostructures and all-dielectric nanostructures have also been widely investigated for improving its performances. In this paper，the working principle and development status of THz-PCAs based on ultrashort pulsed laser are introduced， including theoretical models， substrate materials and different structures of photoconductive antennas. Furthermore， with the dramatic development of source and detector components，THz spectroscopy technology has been utilized in various fields such as chemical detection and substance identification，biomedical application and pharmaceutical industry. THz-TDS is the most commonly used technique in current commercial THz spectroscopy，which has attracted wide attention for its spectral fingerprint，high temporal-spatial resolution，noninvasive and nonionizing properties. Various important biomolecules，such as amino acids，nucleobases and saccharides reveal rich absorption features in THz range. It is verified that THz spectral features originate from the collective molecules of low frequency vibration，rotation and weak interaction with the surrounding molecules（hydrogen bonding，van der Waals force，etc.），so they are very sensitive to the molecular structure and surrounding environment. It is a powerful tool to investigate molecular conformation， positional isomerism of functional groups，intermolecular interactions of organic acids and their salts，optical isomerism，etc. However，it is worth noting that the investigated targets are usually in the form of multi-component mixtures in actual scenario. When the spectral features became more complicated，the much broader THz features would be severely overlapped and accompanied by baseline drift in THz spectra. Identification and quantitative analysis of complex multi-component mixtures will become a great challenge for THz spectral analysis. To overcome such problem，a practical strategy has been proposed by combining machine learning methods with THz-TDS for implementation of practical applications. Moreover，another issue worth noting is conventional free-standing spectroscopy measurement devices are hardly adequate for the detection of microgram level or trace substance. Combination of metamaterials and conventional free-standing THz spectroscopy to enhance the sensing signal is a feasible and effective method，which is crucial for the practicability of clinical adoption. Furthermore，some recent progress we have achieved in THz characteristic spectral technology and its applications are also summarized and discussed. © 2022 Chinese Optical Society. All rights reserved.
  Accession Number: 20223612693702
• Record 357 of
  
  Title:Preparation of Gd 3+-Doped LiYF4: Yb3+/Ho3+Micro-Crystal and the Application Research in Anti-Counterfeiting
  
  Author(s):Wang, Chong(1); Wang, Jing-Hua(1,2); Li, Dong-Dong(1); She, Jiang-Bo(2)
  Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis  Volume: 42  Issue: 11  DOI: 10.3964/j.issn.1000-0593(2022)11-3581-07  Published: November 2022  
  Abstract:The purpose of this paper is to study a rare earth doped luminescence material with good up-conversion luminescence performance, which is of great significance in anti-counterfeiting technology. In order to improve the up-conversion luminescence performance of LiYF 4 : Yb3+/Ho3+micron crystals, a series of Gd 3+-doped LiYF 4 : Yb 3+ /Ho 3+ micron crystals were successfully prepared by hydrothermal synthesis method. XRD and Scanning electron microscope (SEM) were used to characterize the samples' phase purity and crystal morphology. Fluorescence spectrum analyzed the upconversion luminescence properties of LiGd x Y 1- x F 4 : Yb3+/Ho3+micron crystals under 980nm laser excitation. Firstly, the crystal structure, size, morphology and upconversion luminescence properties of LiGd x Y 1- x F 4 : Yb3+/Ho3+micron crystals were investigated. The results show that the XRD diffraction peaks of LiGd x Y 1- x F 4 : Yb 3+ /Ho 3+ micron crystal samples are exactly corresponding to the characteristic peaks of the tetragonal LiYF 4 standard card (PDF#17-0874) without other peaks. The SEM characterization results show that the crystal morphology is octahedral. It shows that LiGd xY1-xF4: Yb3+/Ho3+micron crystal with pure tetragonal phase was successfully synthesized. Fluorescence spectrum test results showed that the up-conversion luminescence intensity of the samples increased first and then decreased with the increase of Gd 3+ion doping concentration and reached the maximum when Gd 3+ion doping concentration was 30 mol%. Secondly, the relationship between the up-conversion luminescence performance and the excitation power of Gd 3+doping concentration of 30 mol% was further studied, and the excitation power was 0.5~1.5 W. The red and green upconversion luminescence intensity ( R/G ) ratio of LiGd 0.3 Y 0.49 F 4 : Yb3+/Ho3+micron crystal only changes about 12% with the increase of excitation power. The upconversion luminescence of LiGd 0.3 Y 0.49 F 4 : Yb3+/Ho3+micron crystal does not change obviously with the increase of excitation power, but still emits stable and bright green light. This phenomenon shows that incorporating Gd 3+ions greatly improves the up-conversion luminescence performance of the samples, and this stable and efficient luminescence performance guarantees its good anti-counterfeiting performance. Finally, LiYF 4 : Yb3+/Ho3+micron crystal powder with Gd 3+ion doping concentration of 30 mol% was mixed with screen metal ink in a certain proportion to produce screen anti-counterfeiting ink, and then the anti-counterfeiting logo pattern of "Xi'an" was printed on the glass base by screen printing technology. After drying treatment, under the excitation of 980 nm laser, it emits bright and stable green visible light, and the anti-counterfeiting logo made has the characteristics of high luminous intensity, easy to identify and not easy to fall off, which can be widely used in the field of anti-counterfeiting. © 2022 Science Press. All rights reserved.
  Accession Number: 20225013227116
• Record 358 of
  
  Title:Polarization-multiplexing achromatic metasurfaces for manipulation of terahertz waves
  
  Author(s):Qin, Chong(1,2); Fan, Wenhui(1,2,3); Wu, Qi(1,2); Jiang, Xiaoqiang(1,2); Yan, Hui(1,2)
  Source: Journal of the Optical Society of America B: Optical Physics  Volume: 39  Issue: 9  DOI: 10.1364/JOSAB.462959  Published: September 2022  
  Abstract:Metasurfaces that can effectively manipulate electromagnetic waves provide a novel solution to realize efficient terahertz functional devices. However, the chromatic aberration of metasurfaces is a remarkable challenge for their extensive applications. Multi-functional metasurfaces are highly desirable in practical applications. Here, we demonstrate polarization-multiplexing achromatic metasurfaces working in the terahertz regime based on anisotropic meta-atoms which exhibit the formbirefringence. Specifically, a polarization-multiplexing achromatic metalens working in the frequency range from 0.8 THz to 1.2 THz is proposed and verified numerically, which can focus terahertz waves within the working bandwidth to different focal planes by varying the polarization state of an incident terahertz wave; the deviation of focal length is less than 8.88% across the whole working bandwidth. In addition, a polarization-multiplexing achromatic deflector working in the frequency range from 0.8 THz to 1.2 THz is also designed and simulated, which can deflect a terahertz wave within the working bandwidth to different directions by manipulating the polarization state of an incident terahertz wave. The metasurfaces demonstrated here are of great significance for the development of ultra-compact, flexible, and multi-functional terahertz devices based on metasurfaces. © 2022 Optica Publishing Group.
  Accession Number: 20223412623257
• Record 359 of
  
  Title:Spirally rotating particles with structured beams generated by phase-shifted zone plates
  
  Author(s):Rafighdoost, Jila(1); Li, Xing(1,2); Zhou, Yuan(1,2); Zhou, Meiling(1); Li, Manman(1); Yan, Shaohui(1); Yao, Baoli(1,2,3)
  Source: Applied Optics  Volume: 61  Issue: 5  DOI: 10.1364/AO.449324  Published: February 10, 2022  
  Abstract:The emerging field of structured beams has led to optical manipulation with tremendous progress. Beyond various methods for structured beams, we use phase-shifted zone plates known as beam-shaping diffractive optical elements to generate beams whose phase exclusively or both phase and intensity are twisted along a curve. These beams can trap and guide particles on open curved trajectories for continuous motion, not necessarily requiring a closed symmetric intensity distribution. We show the feasibility and versatility of the proposed method as a promising technique in optical manipulation in which the trajectory of the spiral rotation and the rate of rotation of trapped particles can be controlled. ©2022 Optica Publishing Group
  Accession Number: 20220711619779
• Record 360 of
  
  Title:Efficient mid-infrared wavelength converter based on plasmon-enhanced nonlinear response in graphene nanoribbons
  
  Author(s):Chi, Jiao(1,3); Liu, Hongjun(1,2); Wang, Zhaolu(1); Huang, Nan(1)
  Source: Journal of Physics D: Applied Physics  Volume: 55  Issue: 11  DOI: 10.1088/1361-6463/ac3e92  Published: March 17, 2022  
  Abstract:Graphene plasmons with enhanced localized electric field have been used for boosting the light-matter interaction in linear optical nano-devices. Meanwhile, graphene is an excellent nonlinear material for several third-order nonlinear processes. We present a theoretical investigation of the mechanism of plasmon-enhanced third-order nonlinearity susceptibility of graphene nanoribbons. It is demonstrated that the third-order nonlinearity susceptibility of graphene nanoribbons with excited graphene surface plasmon polaritons can be an order of magnitude larger than the intrinsic susceptibility of a continuous graphene sheet. Combining these properties with the relaxed phase matching condition due to the ultrathin graphene, we propose a novel plasmon-enhanced mid-infrared (MIR) wavelength converter with arrays of graphene nanoribbons. The wavelength of signal light is in the MIR range, which can excite the tunable surface plasmons polaritons in arrays of graphene nanoribbons. The efficiency of the converter from MIR to near-infrared wavelength can be remarkably improved by 60 times compared with a graphene sheet without graphene plasmons. This work provides a novel idea for the efficient application of graphene in nonlinear optical nano-devices. The proposed MIR wavelength converter is compact, tunable and has promising potential in graphene-based MIR detectors with high detection efficiency. © 2021 IOP Publishing Ltd.
  Accession Number: 20220311461529