2024

• Record 157 of
  
  Title:Hidden phonon highways promote photoinduced interlayer energy transfer in twisted transition metal dichalcogenide heterostructures
  
  Author(s):Johnson, Amalya C.; Georgaras, Johnathan D.; Shen, Xiaozhe; Yao, Helen; Saunders, Ashley P.; Zeng, Helen J.; Kim, Hyungjin; Sood, Aditya; Heinz, Tony F.; Lindenberg, Aaron M.; Luo, Duan; da Jornada, Felipe H.; Liu, Fang
  Source: SCIENCE ADVANCES  Volume: 10  Issue: 4  DOI: 10.1126/sciadv.adj8819  Published: 2024  
  Abstract:Vertically stacked van der Waals (vdW) heterostructures exhibit unique electronic, optical, and thermal properties that can be manipulated by twist-angle engineering. However, the weak phononic coupling at a bilayer interface imposes a fundamental thermal bottleneck for future two-dimensional devices. Using ultrafast electron diffraction, we directly investigated photoinduced nonequilibrium phonon dynamics in MoS2/WS2 at 4 degrees twist angle and WSe2/MoSe2 heterobilayers with twist angles of 7 degrees, 16 degrees, and 25 degrees. We identified an interlayer heat transfer channel with a characteristic timescale of similar to 20 picoseconds, about one order of magnitude faster than molecular dynamics simulations assuming initial intralayer thermalization. Atomistic calculations involving phonon-phonon scattering suggest that this process originates from the nonthermal phonon population following the initial interlayer charge transfer and scattering. Our findings present an avenue for thermal management in vdW heterostructures by tailoring nonequilibrium phonon populations.
  Accession Number: eadj8819
  ISSN: 2375-2548
  eISSN:
• Record 158 of
  
  Title:Fast sampling based image reconstruction algorithm for sheared-beam imaging
  
  Author(s):Chen, Ming-Lai; Ma, Cai-Wen; Hui, Liu; Luo, Xiu-Juan; Feng, Xu-Bin; Yue, Ze-Lin; Jing, Zhao
  Source: ACTA PHYSICA SINICA  Volume: 73  Issue: 2  DOI: 10.7498/aps.73.20231254  Published: 2024  
  Abstract:Sheared-beam imaging (SBI) is an unconventional ground-based optical imaging technique. It breaksthrough the traditional optical imaging concept by using three coherent laser beams, which are laterallydisplaced at the transmit plane, to illuminate the target, reconstructing the target image from echo signals.However, the echo data sampling of the imaging system is still not fast enough to reconstruct the highresolution and clear image of the target when imaging the target that is at rapidly changing position andattitude. In order to solve this problem, in this work an image reconstruction method is proposed based on five-beam fast sampling. An emitted beam array arranged in the cross shape with a central symmetrical structure isproposed, and the encoding and decoding method of the imaging system are changed. With a single exposure,the echo signals carry more spectrum information of the target, and the number of reconstructed images can beincreased from 1 to 8, which quickly suppresses the speckle effect of the reconstructed image. Firstly, theprinciple of the imaging technique based on fast sampling is presented. Then, an image reconstruction algorithmbased on fast sampling is studied. Eight groups of phase differences and amplitude information of the target canbe extracted from echo signals. The wavefront phases are solved by the least-squares method, and wavefrontamplitude can be obtained by the algebraic operation of speckle amplitude. The target image is reconstructedby the inverse Fourier transform. The simulation results show that comparing with the traditional three-beamimage reconstruction method, the sampling times of echo data needed to obtain the same quality image arereduced from 20 to 5, which greatly reduces the sampling times of echo data and improves the sampling rate of echo data
  Accession Number: 24202
  ISSN: 1000-3290
  eISSN:
• Record 159 of
  
  Title:Direct femtosecond laser writing fiber Bragg gratings in double-D cladding chalcogenide glass infrared fibers
  
  Author(s):Liu, Lutao; Li, Xingyong; Xu, Yantao; Chen, Fengyi; Xiao, Xusheng; He, Wentao; Wang, Ruohui; Zhang, Peiqing; Yu, Yongsen; Guo, Haitao
  Source: OPTICS AND LASER TECHNOLOGY  Volume: 174  Issue:   DOI: 10.1016/j.optlastec.2024.110586  Published: 2024  
  Abstract:Chalcogenide glass (ChG) fiber Bragg grating (FBG) is one of the key components in monolithic infrared fiber lasers and sensors. However, its effective fabrication using direct femtosecond laser writing is still seldom reported, owing to complications attributable to ChG. In this study, a double-D shaped ChG fiber was used to fabricate FBGs with high reflectivity (a 20.5 dB dip in the transmittance) and narrow 3-dB bandwidth (164 pm) using direct femtosecond laser writing. The high sensitivity to laser powers of the direct writing of the ChG FBG was revealed and understood from the perspective of the low laser-induced damage threshold of ChGs. Lowerorder reflectance of the directly written FBGs at the mid-infrared wavelength region were quantitively predicted to have higher reflectivity. These results provide a robust method of writing FBGs with arbitrary periods in ChG fibers, establishing a solid foundation for the development of infrared fiber lasers and fiber sensors.
  Accession Number: 110586
  ISSN: 0030-3992
  eISSN: 1879-2545
• Record 160 of
  
  Title:Optical force on a Rayleigh particle generated by photonic jet
  
  Author(s):Wei, Bojian; Chen, Run; Xu, Qiang; Li, Renxian; Gong, Shuhong; Yan, Shaohui
  Source: OPTICAL REVIEW  Volume: 31  Issue: 1  DOI: 10.1007/s10043-023-00857-1  Published: 2024  
  Abstract:The optical force exerted on a Rayleigh dielectric spherical particle by a photonic jet is investigated in the framework of the Rayleigh approximation. The photonic jet is generated by a plane wave illuminating a Generalized Luneburg Lens (GLLs). The electric field of the photonic jet is calculated using Discrete Dipole Approximation (DDA). The effects of wavelength of incident plane wave, focal length and radius of the GLLs on optical force are analyzed. Numerical results show that the stability of the captured particles can be controlled by changing the incident wavelength, focal length and radius of the GLLs.
  Accession Number:
  ISSN: 1340-6000
  eISSN: 1349-9432
• Record 161 of
  
  Title:High repetition frequency tunability active Q-switched all-fiber laser by multi-gain sub-rings smoothing multipeak pulse and suppressing ASE self-saturation
  
  Author(s):Chen, Xuechun; Wang, Nan; He, Chaojian; Xu, Shuang; Ning, Chaoyu; Li, Xinyao; Dong, Zhiyong; Yang, Yingying; Yang, Guowen; Lin, Xuechun
  Source: OPTICS EXPRESS  Volume: 32  Issue: 2  DOI: 10.1364/OE.515391  Published: 2024  
  Abstract:This paper provides a method to effectively suppress the severe ASE self-saturation when achieving high repetition frequency tunability with high output power and narrow pulse width in active Q-switched all -fiber lasers. By studying the regularity of the system's multi-stable state, we first ensured that the laser system operated in a steady state. Then output avoids uneven distribution of pulse energy or missing pulses due to period bifurcation state or chaos state. By adding multiple gain sub -rings within the cavity, the sub -ring structure itself indirectly mitigates the ASE self-saturation while smoothing the pulse. The method will avoid the severe power loss caused by traditional smoothing methods by adjusting the AOM rising edge time. It will also avoid lowering the ASE lasing threshold at high repetition frequency. Meanwhile, the intra-cavity backward ASE can be effectively absorbed by inserting the gain fiber in the sub -rings to directly mitigate the ASE self-saturation. The system's continuously adjustable repetition frequency can be as high as over 300 kHz. It ensures that output power above the watt level and a < 0.2 nm narrow bandwidth can be maintained while tuning the repetition frequency. The narrowest smoothing pulse width of 28 ns has been reached.
  Accession Number:
  ISSN: 1094-4087
  eISSN:
• Record 162 of
  
  Title:Single line of sight frame camera based on the RadOptic effect of ultrafast semiconductor detector
  
  Author(s):Liu, Yiheng; He, Kai; Yan, Xin; Gao, Guilong; Du, Wanyi; Shang, Yang; Wang, Gang; Wang, Tao; Zhang, Jun; Tian, Jinshou; Tan, Xiaobo
  Source: OPTICS AND LASERS IN ENGINEERING  Volume: 175  Issue:   DOI: 10.1016/j.optlaseng.2024.108029  Published: 2024  
  Abstract:A new optical beam splitting method is proposed, based on which the optical frame camera capable of capturing multiple frames in a single exposure is designed and experimentally verified. The operation of the frame camera is based on an ultra-fast response semiconductor detector. It is equipped with an optical beam splitter and an optical imaging module. The ultrafast semiconductor detector receives an optical pulse that produces a transient refractive index change, and ultrafast physical processes are recorded by diffracting the probe laser through the transient phase grating. The interaction of an X-ray pulse with a semiconductor detector to produce a phase grating is simulated, based on the Monte Carlo method. The optical beam splitting mode separates a laser into two optical pulses with a certain time difference in the direction of polarization perpendicular to each other. The imaging module filters the diffracted probe laser in the spectral plane and then images multiple frames. The frame camera was used to record the temporal and spatial distribution characteristics of femtosecond laser pulses with a temporal resolution of 4.1 ps. This frame camera has great potential and value for applying to experimental studies of inertial confinement fusion.
  Accession Number: 108029
  ISSN: 0143-8166
  eISSN: 1873-0302
• Record 163 of
  
  Title:Enantioselective Optical Trapping of Multiple Pairs of Enantiomers by Focused Hybrid Polarized Beams
  
  Author(s):Zhang, Yanan; Li, Manman; Yan, Shaohui; Zhou, Yuan; Gao, Wenyu; Niu, Ruixin; Xu, Xiaohao; Yao, Baoli
  Source: SMALL  Volume:   Issue:   DOI: 10.1002/smll.202309395  Published: 2024  
  Abstract:Enantiomers (opposite chiral molecules) usually exhibit different effects when interacting with chiral agents, thus the identification and separation of enantiomers are of importance in pharmaceuticals and agrochemicals. Here an optical approach is proposed to enantioselective trapping of multiple pairs of enantiomers by a focused hybrid polarized beam. Numerical results indicate that such a focused beam shows multiple local optical chirality of opposite signs in the focal plane, and can trap the corresponding enantiomers near the extreme value of optical chirality density according to the handedness of enantiomers. The number and positions of trapped enantiomers can be changed by altering the value and sign of polarization orders of hybrid polarized beams, respectively. The key to realizing enantioselective optical trapping of enantiomers is that the chiral optical force exerted on enantiomers in this focused field is stronger than the achiral optical force. The results provide insight into the optical identification and separation of multiple pairs of enantiomers and will find applications in chiral detection and sensing. This work proposes an optical approach to enantioselective trapping of multiple pairs of nano-enantiomers (S and R) by a type of hybrid polarized beams. The enantiomers with opposite chirality can be trapped at different positions depending on whether the handedness of enantiomer matches the sign of optical chiral density at the trapping positions (P1-P6).image
  Accession Number:
  ISSN: 1613-6810
  eISSN: 1613-6829
• Record 164 of
  
  Title:Material removal and surface generation mechanisms in rotary ultrasonic vibration-assisted aspheric grinding of glass ceramics
  
  Author(s):Sun, Guoyan; Wang, Sheng; Zhao, Qingliang; Ji, Xiabin; Ding, Jiaoteng
  Source: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY  Volume: 130  Issue: 7-8  DOI: 10.1007/s00170-023-12904-x  Published: 2024  
  Abstract:High-efficiency precision grinding can shorten the machining cycle of aspheric optical elements by a factor of 2-10. To achieve this objective, ultrasonic vibration (UV)-assisted grinding (UVG) has been increasingly applied to manufacture aspheric optics. However, the mechanisms of material removal and surface formation in UV-assisted aspheric grinding of glass ceramics have rarely been studied. Herein, rotary UV-assisted vertical grinding (RUVG) was used to explore the machining mechanism of coaxial curved surfaces. First, RUV-assisted scratch experiments were conducted on aspheric surface of glass ceramics, which exhibited multiple benefits over conventional scratching. These include a reduction in the scratch force by 37.83-44.55% for tangential component and 3.87-28.15% for normal component, an increase in plastic removal length by 43.75%, and an increase in material removal rate by almost a factor of 2. Moreover, grinding marks on the aspheric surface in RUVG were accurately simulated and optimized by adjusting grinding parameters. RUVG experiments were performed to verify the accuracy of grinding texture simulations and investigate the UV effect. The results demonstrate that UV can improve the surface quality of aspheric grinding when compared with conventional vertical grinding. In particular, the total height of the profile of form accuracy and its root mean square were significantly improved by a factor of 3.38-4.54 and 7.15-10.82, respectively, and the surface roughness reduced by 10.03-12.10%. This study provides deeper insight into material removal and surface generation mechanisms for RUVG of aspheric surfaces, and it is thus envisaged that these results will be useful in engineering applications.
  Accession Number:
  ISSN: 0268-3768
  eISSN: 1433-3015
• Record 165 of
  
  Title:Spectroscopic properties and numerical analysis of novel erbium doped multi-component tellurite glasses
  
  Author(s):Wan, Rui; Guo, Chen; Li, Xianda; Wang, Pengfei
  Source: CERAMICS INTERNATIONAL  Volume: 50  Issue: 4  DOI: 10.1016/j.ceramint.2023.12.085  Published: 2024  
  Abstract:In this paper, Er3+ doped TeO2-ZnF2-BaF2-KF-Ta2O5 tellurite glasses with low hydroxyl content (-0.03 x 10-19 cm- 3) were investigated employing both glass composition and glass melting process optimization. The Raman spectra and physical properties were characterized to analyze the structure of the glasses. Under the pumping of 980 nm LD laser, intense up-conversion fluorescence at 1.5 and 2.7 mu m of samples and their lifetimes were detected and analyzed, and the related transition mechanisms with gradient-varying Er3+ doping concentrations were discussed. The maximum absorption and emission cross section at 2.7 mu m was calculated to be 6.4 x 10-21 cm2 and 6.8 x 10-21 cm2, correspondingly, which were higher than those of traditional tellurite glasses. Using the calculated and measured spectroscopic parameters of bulk tellurite glass, a dual-wavelength pumping model was established to verify the feasibility of mid-infrared laser output in similar tellurite glass fiber. Experimental results support the assertion that the Er3+ doped tellurite glasses hold promise as a candidate laser gain medium for mid-infrared fiber laser systems.
  Accession Number:
  ISSN: 0272-8842
  eISSN: 1873-3956
• Record 166 of
  
  Title:O-band reconfigurable silicon polarization rotator
  
  Author(s):Bai, Yawen; Wang, Pengfei; Peng, Bo; Chu, Tao
  Source: CHINESE OPTICS LETTERS  Volume: 22  Issue: 1  DOI: 10.3788/COL202422.011303  Published: 2024  
  Abstract:Silicon waveguides typically exhibit optical anisotropy, which leads to polarization correlation and single-polarization operations. This consequently creates a demand for polarization-control devices. This paper introduces a CMOS-compatible O-band reconfigurable TE/TM polarization rotator comprising two symmetrical polarization rotator-splitters and phase shifters. This configuration enables dynamic conversion of any linear polarization to its quadratic equivalent. Experimental results indicate that the reconfigurable polarization rotator exhibits an insertion loss of less than 1.5 dB. Furthermore, the bandwidth for a polarization extinction ratio beyond 15 dB exceeds 60 nm.
  Accession Number: 11303
  ISSN: 1671-7694
  eISSN:
• Record 167 of
  
  Title:Compressed Spectrum Reconstruction Method Based on Coding Feature Vector Enhancement
  
  Author(s):Cao, Chipeng; Li, Jie; Wang, Pan; Qi, Chun
  Source: IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING  Volume: 62  Issue:   DOI: 10.1109/TGRS.2023.3347220  Published: 2024  
  Abstract:Compressive spectral imaging (CSI) is a snapshot spectral imaging technique that rapidly captures the spectral information of a target in a single exposure and effectively reconstructs high spectral data using reconstruction algorithms. However, due to the presence of a large number of identical pixels in the measured image, which map to different prior spectral information, existing algorithms struggle to establish an accurate pixel separation representation model. To improve the separation effect between pixels and enhance the representation capability of the measured image pixels, we propose a compressed spectral reconstruction method with enhanced encoding feature vectors. By designing encoding information calculation rules based on a combination of linear and nonlinear functions, encoding features are calculated according to the spatial coordinate position information and wavelength information of the pixels, effectively enhancing the separation representation characteristics between channels and neighboring pixels through the addition of encoding features. Furthermore, by utilizing the semantic similarity between the predicted results of the prior model and the prior spectral image, the reconstruction problem is transformed into a total variation (TV) minimization problem between the predicted results of the prior model and the reconstruction results, combined with the alternating direction method of multipliers (ADMMs) to achieve accurate pixel reconstruction. The experimental setup utilizes a dual-camera compressed spectral imaging (DCCHI) system, consisting of a dual-dispersion coded aperture compressed spectral imaging (DD-CASSI) system and a grayscale imaging system. Various experiments have shown that the proposed method outperforms in reconstructing quality and displays superior algorithmic performance.
  Accession Number: 5503016
  ISSN: 0196-2892
  eISSN: 1558-0644
• Record 168 of
  
  Title:Fast and Robust Restoration of Single Photon 3D Data Using Parameterized Kernel
  
  Author(s):Chen, Songmao; Su, Xiuqin; Zhang, Zhenyang; Xu, Weihao; Wang, Jie; Hao, Wei
  Source: IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS  Volume: 30  Issue: 1  DOI: 10.1109/JSTQE.2023.3269747  Published: 2024  
  Abstract:Single photon 3D imaging is an emerging topic for optronic sensing under extreme scenarios (e.g. spaceborne altimeter, long range imaging). However, such technique suffers from low photon counts and strong noise, which is due to either strong attenuation from the environment or reduced acquisition time. Although state-of-the-art algorithms have been proposed to achieve high resolution results from corrupted single photon 3D data, the trade-off between the restoration performance and computational complexity remains challenging. This paper presents a fast and robust restoration approach for single photon 3D data, which adaptively smooth the sparse and noisy histogram by applying a parameterized kernel and finally reconstruct the 3D image using matched filter. The implementation can be fast as the core step of the processing is generalized as a 3D convolution that can be solved by Fast Fourier Transform (FFT). The method is validated on various conditions and scenarios from Middbury dataset and real data, where the proposed method showed robust results as the competing state-of-the-art algorithms with fast implementation.
  Accession Number: 9900008
  ISSN: 1077-260X
  eISSN: 1558-4542