2022

• Record 37 of
  
  Title:Tunable depth of focus with modified complex amplitude modulation of an optical field
  
  Author(s):Yin, Weiyu(1,2); Yang, Yanlong(1); Yang, Ruiwen(1); Yao, Baoli(1,2,3)
  Source: Applied Optics  Volume: 61  Issue: 12  DOI: 10.1364/AO.453313  Published: April 20, 2022  
  Abstract:Bessel beams have nondiffraction and self-healing properties in the propagation direction and are widely used in particle optical manipulation and optical microscopy. Bessel beams can be generated by axicons or spatial light modulators, which can produce a zero-order or high-order Bessel beam with different parameters depending on the specific application. The modulation of Bessel beams achieved in the spatial spectrum domain by optimization algorithms has a low light energy utilization rate due to the small effective modulation region. We propose a Bessel-like beam phase generation algorithm based on an improved iterative optimization algorithm directly in the spatial domain to achieve a tunable modulation of the beam’s length and the axial center position. The optimization time is reduced from minutes to seconds relative to the genetic algorithm, providing a new means of modulation for different applications in various fields. © 2022 Optica Publishing Group
  Accession Number: 20221712008609
• Record 38 of
  
  Title:Design of Passive Constant-Force End-Effector for Robotic Polishing of Optical Reflective Mirrors
  
  Author(s):Zhang, Jian(1,2); Zhao, Liangxiao(2,3); Li, Lingling(4); Ma, Fulei(1); Chen, Guimin(4)
  Source: Chinese Journal of Mechanical Engineering (English Edition)  Volume: 35  Issue: 1  DOI: 10.1186/s10033-022-00811-3  Published: December 2022  
  Abstract:Polishing plays an indispensable role in optical processing, especially for large-aperture optical reflective mirrors with freeform surfaces. Robotic polishing requires effective control of the contact force between the robot and the mirror during processing. In order to maintain a constant contact force during polishing, traditional polishing robots rely on closed-loop control of air cylinders, whose performances heavily rely on high-fidelity force sensing and real-time control. This paper proposes to employ a compliant constant-force mechanism in the end-effector of a polishing robot to passively maintain a constant force between the robot and the mirror, thus eliminating the requirement for force sensing and closed-loop control. The compliant constant force mechanism utilizing the second bending mode of fixed-guided compliant beams is adopted and elaborated for the passive end-effector. An end-effector providing a constant contact force of 40 N is designed and prototyped. The polishing experiment shows that the passive constant-force end-effector provides stable contact force between the robot and the mirror with fluctuation within 3.43 N, and achieves RMS (Root Mean Square) lower than λ/10 (λ = 632.8 nm) of the polished surface of the large-aperture optical reflective mirror. It is concluded that the constant-force compliant mechanism provides a low-cost and reliable solution for force control in robotic polishing. © 2022, The Author(s).
  Accession Number: 20224813171456
• Record 39 of
  
  Title:Single-scan polarization-resolved degenerate four-wave mixing spectroscopy using a vector optical field
  
  Author(s):Yuan, Jiaqi(1,2); Cheng, Xuemei(1,2); Wang, Xing(2); Jiao, Tengfei(1); Ren, Zhaoyu(1)
  Source: Photonics Research  Volume: 10  Issue: 1  DOI: 10.1364/PRJ.423799  Published: January 1, 2022  
  Abstract:We report on a new method to achieve the single-scan polarization-resolved degenerate four-wave mixing (DFWM) spectroscopy in a Rb atomic medium using a vector optical field, in which two pump beams are kept linearly polarized and a vector beam is employed as the probe beam. As the polarization and intensity of the DFWM signal are closely dependent on the polarization state of the probe beam, a vector probe beam with space-variant states of polarization is able to generate a DFWM signal with space-variant states of polarization and intensity across the DFWM image. Accordingly, the polarization-resolved spectra can be retrieved from a single DFWM image. To the best of our knowledge, this is the first time that the single-scan polarization-resolved spectrum detection has been realized experimentally with a vector beam. This work provides a simple but efficient single-scan polarization-resolved spectroscopic method, which would be of great utility for the samples of poor light stability and fast optical processes. © 2021 Chinese Laser Press
  Accession Number: 20220311466764
• Record 40 of
  
  Title:Alignment technology based on a central small aperture for the AIMS telescope
  
  Author(s):Shen, Yuliang(1,2); Kewei, E.(3); Fu, Xing(3); Wang, Dongguang(1); Hou, Junfeng(1,2); Liang, Ming(4); Xu, Songbo(3)
  Source: Applied Optics  Volume: 61  Issue: 19  DOI: 10.1364/AO.459464  Published: July 1, 2022  
  Abstract:The accurate infrared solar magnetic field measurement system (AIMS) is a 1 m off-axis Gregorian alt-azimuth solar telescope and will be dedicated to measuring the solar magnetic field in mid-infrared. How to align the large-aperture off-axis system is a significant issue. Sub-aperture stitching with the small-aperture standard flat mirror can be applied to the alignment of the large-aperture off-axis system. However, this method is time-consuming and inefficient. We propose an alignment method based on the Zernike polynomials of the central small aperture to solve the low efficiency of sub-aperture stitching. Theoretical simulation shows that the RMS residual error of the system after using the central small-aperture alignment method will be less than 4.5 ∗ 10−6λ at 632.8 nm. Practical alignment suggests that our method can make the RMS value of full-aperture wave aberration quickly converge to 0.12λ at 632.8 nm. Compared with the sub-aperture stitching method, our method can significantly reduce the times of sub-aperture stitching and save the alignment time. © 2022 Optica Publishing Group
  Accession Number: 20222812335848
• Record 41 of
  
  Title:Scanning dual-microcomb spectroscopy
  
  Author(s):Wang, Yang(1,2); Wang, Zhichuang(1,2); Wang, Xinyu(1,2); Shao, Wen(1,2); Huang, Long(1,2); Liang, Bo(1,2); Little, Brent E.(1,2); Chu, Sai T.(3); Zhao, Wei(1,2); Wang, Weiqiang(1,2); Zhang, Wenfu(1,2)
  Source: Science China: Physics, Mechanics and Astronomy  Volume: 65  Issue: 9  DOI: 10.1007/s11433-022-1920-6  Published: September 2022  
  Abstract:Dual-comb spectroscopy (DCS) is a powerful tool in molecular spectroscopy benefiting from the advantages of high resolution and short measurement time. The recently developed soliton microcomb (SMC) can potentially transfer the dual-comb method to an on-chip platform. In this paper, we demonstrate DCS using two frequency scanning SMCs, termed scanning dual-microcomb spectroscopy (SDMCS). The two SMCs are generated by an auxiliary-assisted thermal balance scheme, and the pump laser frequency sweeps over one free spectral range of the microresonator (∼49 GHz) using a feedback control system. The proposed SDMCS has a spectral resolution of 12.5 MHz, which is determined by the minimum sweeping step of the pump laser. Using this SDMCS system, we perform three types of gas molecule absorption spectroscopy recognition and gas concentration detection. This study paves the way for integrated DCS with a high signal-to-noise ratio, high spectral resolution, and fast acquisition rate. © 2022, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.
  Accession Number: 20223112521814
• Record 42 of
  
  Title:Encoding and decoding communications based on perfect vector optical vortex arrays
  
  Author(s):Long, Zixu(1,2); Hu, Huajie(1); Ma, Xin(1,2); Tai, Yuping(3); Li, Xinzhong(1,2)
  Source: Journal of Physics D: Applied Physics  Volume: 55  Issue: 43  DOI: 10.1088/1361-6463/ac8d13  Published: October 27, 2022  
  Abstract:We proposed the perfect vector optical vortex arrays (PVOVAs) for encoding and decoding communications, including the 2 × 2, 1 × 4, 4 × 4, and 2 × 4 array forms, which were generated with the coaxial superposition of two vector optical vortex arrays with left- and right-handed circular polarization. The polarization order and state of each vector element could be modulated independently by adjusting the corresponding topological charges and additional phases, θn . By attaching code information to these vector elements with different states of polarization, the hexadecimal code elements, including 0 to F, were represented. Therefore, PVOVAs consisting of multiple vector elements can transmit encoding information and be decoded as original information in the receiving end. The school badge grayscale image, with a size of 64 × 64 pixels, was transmitted using the encoding and decoding communication via PVOVAs, and the received restored image had a reliable accuracy. This study proves PVOVAs have flexible spatial structure and controllable states of polarization, and it expands the application of vector optical fields in optical encoding and decoding communication. © 2022 IOP Publishing Ltd.
  Accession Number: 20223812778771
• Record 43 of
  
  Title:A Polygon-Like Light-Arm Zone Plate
  
  Author(s):Xia, Tian(1,4); Cheng, Shubo(2); Yu, Weixing(3); Xie, Wenke(1,4); Tao, Shaohua(1,4)
  Source: IEEE Photonics Technology Letters  Volume: 34  Issue: 7  DOI: 10.1109/LPT.2022.3158808  Published: April 1, 2022  
  Abstract:A polygon-like light-arm zone plate (PLZP) is proposed to generate the polygon-like light-arm beam, whose arms are identified clearly by using the appropriate transverse azimuthal shift varphi . Moreover, varphi has influence on the beam shape. The PLZP is based on the spiral phase plate of the topological charge l and the multiplexed vortex spiral phase plate of the topological charges l_{1} and l_{2}. In addition, when the radius of the circular area for the filter is small or big, the number of arms is vert l_{2}-lvert or vert l_{1}-l vert , respectively. Furthermore, when l_{2} is positive or negative, the rotation direction of arms is clockwise or anticlockwise respectively. The proposed zone plates can be used to trap particles into different shapes, and applicable for optical communication. © 1989-2012 IEEE.
  Accession Number: 20221111799867
• Record 44 of
  
  Title:Extended bifocal depth imaging with modified generalized composite kinoform Fibonacci lenses
  
  Author(s):Xia, Tian(1,2); Cheng, Shubo(3); Yu, Weixing(2); Tao, Shaohua(1,4)
  Source: Optics and Laser Technology  Volume: 152  Issue:   DOI: 10.1016/j.optlastec.2022.108162  Published: August 2022  
  Abstract:A modified generalized composite kinoform Fibonacci lens (MGCKFiL) is proposed to produce two foci with the same resolution and long focal depths. The MGCKFiL is based on a generalized composite kinoform Fibonacci lens (GCKFiL) and a phase generated by the weighted Gerchberg-Saxton algorithm. This phase expands the focal depths of two foci for the GCKFiL. Compared with the conventional kinoform Fibonacci lens (KFiL), the GCKFiL has the two equal-intensity foci with higher intensity. The GCKFiL with the positive integer number p = 4q + 2 has the two equal-intensity foci along the optic axis. When p is big enough, the bifocal positions of the GCKFiL with the bigger order S have the ratio rounding toward one. Furthermore, the MGCKFiL has the two images with the same size at the two main focal positions, and achieves the extended bifocal depth imaging. The proposed zone plates are applicable to generate the two same-size images, and achieve extended bifocal depth imaging and multi-planar optical trapping. © 2022
  Accession Number: 20221511957757
• Record 45 of
  
  Title:Polarization-Dependent Scattering of Nanogratings in Femtosecond Laser Photowritten Waveguides in Fused Silica
  
  Author(s):Cheng, Guanghua(1); Lin, Ling(2); Mishchik, Konstantin(3); Stoian, Razvan(3)
  Source: Materials  Volume: 15  Issue: 16  DOI: 10.3390/ma15165698  Published: August 2022  
  Abstract:The properties of polarization-selective, light-guiding systems upon subwavelength nanogratings formation in the case of type II refractive index traces induced by femtosecond laser pulses in bulk fused silica were studied. Polarization-dependent scattering is analyzed both in simulation using a finite-difference, time-domain method and in experiments. We argue that the polarization-sensitive optical guiding of type II waveguides is due to polarization-dependent scattering of nanogratings. Optical designs can then be suggested where the guiding efficiency of type I traces can be combined with type II anisotropies. A low-loss waveguide polarizer is demonstrated based on the modulation of the evanescent field emerging from type I waveguides using polarization-dependent scattering of neighboring nanogratings. © 2022 by the authors.
  Accession Number: 20223712731448
• Record 46 of
  
  Title:Simulation of Mesosphere Wind Measurement with Multiple Emission Lines of the O2(0-1) Band Using Space-Based Doppler Asymmetric Spatial Heterodyne
  
  Author(s):Fu, Di(1,2); Zhao, Hengxiang(1); Li, Juan(1); Wu, Kuijun(3); Chang, Chenguang(1,2); Bai, Lu(4); Feng, Yutao(1); Liu, Xuebin(1)
  Source: Atmosphere  Volume: 13  Issue: 8  DOI: 10.3390/atmos13081309  Published: August 2022  
  Abstract:For space-based atmospheric wind measurements, full-link simulation is critical for the optimization of the instrument indicators and the evaluation of the measurements’ performance. This paper presents observation simulations and error verification of the mesosphere wind measurement with four emission lines of the O2(0-1) band by using the space-based Doppler Asymmetric Spatial Heterodyne (DASH), named the Mesosphere Wind Image Interferometer (MWII). The passive wind measurement principle and the DASH concept are first described. The full-link simulation consists of radiation simulation, the instrument forward model, and the wind retrieval model. The four emission lines at about 866.5 nm of the O2(0-1) band were selected as the observation targets. The radiation characteristics of the target lines were studied and calculated, as well as the background radiation. Based on the LOS radiation integral model, a numerical simulation of the raw observation data was carried out using the instrument model. The interference fringe priority strategy and joint wind decision method were proposed to achieve multiple-emission-line wind retrieval with higher precision. In the simulation, multiple-line retrieval could improve the precision by more than 30% compared to single-line retrieval under the same conditions. The error simulation indicated that the wind profile precision was 3–9 m/s in the altitude range of 50–110 km, with an average accuracy of about 1 m/s, proving that the scheme of MWII has good altitude coverage of the whole mesosphere and a part of the lower thermosphere. © 2022 by the authors.
  Accession Number: 20223712709636
• Record 47 of
  
  Title:Refinement method for compressive hyperspectral data cubes based on self-fusion
  
  Author(s):Zhu, Mengjun(1); Yi, Wenjun(1); Dong, Zhaohua(2); Xiong, Peng(2); Du, Junyi(2); Tang, Xingjia(3); Yang, Ying(3); Li, Libo(3); Qi, Junli(1); Liu, Ju(4); Li, Xiujian(1)
  Source: Journal of the Optical Society of America A: Optics and Image Science, and Vision  Volume: 39  Issue: 12  DOI: 10.1364/JOSAA.465165  Published: December 1, 2022  
  Abstract:Compressive hyperspectral images often suffer from various noises and artifacts, which severely degrade the imaging quality and limit subsequent applications. In this paper, we present a refinement method for compressive hyperspectral data cubes based on self-fusion of the raw data cubes, which can effectively reduce various noises and improve the spatial and spectral details of the data cubes. To verify the universality, flexibility, and extensibility of the self-fusion refinement (SFR) method, a series of specific simulations and practical experiments were conducted, and SFR processing was performed through different fusion algorithms. The visual and quantitative assessments of the results demonstrate that, in terms of noise reduction and spatial–spectral detail restoration, the SFR method generally is much better than other typical denoising methods for hyperspectral data cubes. The results also indicate that the denoising effects of SFR greatly depend on the fusion algorithm used, and SFR implemented by joint bilateral filtering (JBF) performs better than SRF by guided filtering (GF) or a Markov random field (MRF). The proposed SFR method can significantly improve the quality of a compressive hyperspectral data cube in terms of noise reduction, artifact removal, and spatial and spectral detail improvement, which will further benefit subsequent hyperspectral applications. © 2022 Optica Publishing Group.
  Accession Number: 20230313384959
• Record 48 of
  
  Title:Mid-infrared broadband optical frequency comb generated in MgF2 resonators
  
  Author(s):Wu, Wei(1,2); Sun, Qibing(1,2); Wang, Yi(1,2); Yang, Yu(3); Ming, Xianshun(1); Shi, Lei(1,2); Wang, Keyi(3); Zhao, Wei(1,2); Wang, Leiran(1,2)
  Source: Photonics Research  Volume: 10  Issue: 9  DOI: 10.1364/PRJ.459478  Published: August 1, 2022  
  Abstract:Microresonator-based optical frequency combs are broadband light sources consisting of equally spaced and coherent narrow lines, which are extremely promising for applications in molecular spectroscopy and sensing in the mid-infrared (MIR) spectral region. There are still great challenges in exploring how to improve materials for microresonator fabrication, extend spectral bandwidth of parametric combs, and realize fully stabilized soliton MIR frequency combs. Here, we present an effective scheme for broadband MIR optical frequency comb generation in a MgF2 crystalline microresonator pumped by the quantum cascade laser. The spectral evolution dynamics of the MIR Kerr frequency comb is numerically investigated, revealing the formation mechanism of the microresonator soliton comb via scanning the pump-resonance detuning. We also experimentally implement the modulation instability state MIR frequency comb generation in MgF2 resonators covering from 3380 nm to 7760 nm. This work proceeds microresonator-based comb technology toward a miniaturization MIR spectroscopic device that provides potential opportunities in many fields such as fundamental physics and metrology. © 2022 Chinese Laser Press.
  Accession Number: 20223912791132