2024

• Record 109 of
  
  Title:Enantioselective Optical Trapping of Multiple Pairs of Enantiomers by Focused Hybrid Polarized Beams
  
  Author(s):Zhang, Yanan(1,2); Li, Manman(1); Yan, Shaohui(1); Zhou, Yuan(1,2); Gao, Wenyu(1,2); Niu, Ruixin(1,2); Xu, Xiaohao(1); Yao, Baoli(1,2)
  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. © 2024 Wiley-VCH GmbH.
  Accession Number: 20240215352673
• Record 110 of
  
  Title:Miniaturizable Phase-Sensitive Amplifier Based on Vector Dual-Pump Structure for Phase Regeneration of PDM Signal
  
  Author(s):Jia, Shuaiwei(1,2); Xie, Zhuang(1,2); Shao, Wen(1,2); Han, Xiaotian(1,2); Su, Yulong(3); Meng, Jiacheng(1); Gao, Duorui(1); Wang, Wei(1); Xie, Xiaoping(1,2)
  Source: IEEE Photonics Journal  Volume: 16  Issue: 1  DOI: 10.1109/JPHOT.2023.3335923  Published: February 1, 2024  
  Abstract:Phase sensitive amplification is indispensable in promoting applications such as all-optical regenerators, quantum communications, all-optical analog-to-digital conversion, and long-distance communications. In this article, we proposed a vector dual-pump nondegenerate phase-sensitive amplification scheme based on ultra-silicon-rich nitride (Si7N3) waveguide, and theoretically verified its capability for all-optical regeneration of phase-encoded polarization-division multiplexing (PDM) signal without the need for complex polarization diversity structures. We achieved a gain extinction ratio (GER) of ∼37.5 dB by using a 3-mm-long Si7N3 waveguide with a high nonlinear coefficient (∼279 /W/m). Signal quality before and after regeneration is characterized by constellation diagram and error vector magnitude (EVM). The results show that the EVM of the degraded PDM differential phase-shift keying (DPSK) signals with two polarization states of 54% and 53.8%, can be improved to 13.6% and 13.6%, respectively, after regeneration, directly illustrating the remarkable phase noise suppression effect. The applicability of the scheme in PDM quadrature phase shift keying (QPSK) signals was further investigated. Similarly, the EVMs of the two polarization states of the deteriorated QPSK signals are optimized from 28.9% and 29.3% to 13.7% and 13.9%, respectively. The proposed scheme has promising applications in integrated all-optical processing systems and long-distance transmission of optical communications. © 2009-2012 IEEE.
  Accession Number: 20240215344693
• Record 111 of
  
  Title:Fabrication and Mid-Infrared Laser Transmission Performance of Ultra-Low Loss Chalcogenide Glass Fibers
  
  Author(s):Xu, Yantao(1); Guo, Haitao(1); Xiao, Xusheng(1); Li, Man(2); Yan, Mengmeng(2)
  Source: Guangxue Xuebao/Acta Optica Sinica  Volume: 44  Issue: 7  DOI: 10.3788/AOS232009  Published: April 2024  
  Abstract:Objective With the continuous development of infrared optics, the demand for infrared laser transmission in such fields as national defense and security, biomedicine, and advanced manufacturing is becoming increasingly urgent, and therefore infrared energy transmission fibers are receiving increasing attention. The chalcogenide glass, as an excellent infrared material, features a wide transmission range, stable physic-chemical properties, and easy fiber formation, which makes it an ideal material for infrared energy transmission fibers. The high optical loss of domestically produced chalcogenide glass fibers currently limits their widespread applications. The origin of the optical loss for chalcogenide glass fibers mainly includes the absorption loss of C, H, O, and other impurities; scattering loss caused by heterogeneous particle impurities and striae; scattering loss caused by the interface defects between the core and cladding. For suppressing the absorption loss and scattering loss in chalcogenide glasses and obtaining ultra-low loss fibers, gas (chlorine gas)-gas (glass vapor) and solid (aluminum)-liquid (glass melt) chemical reactions are employed to reduce the absorption loss of fibers. A three-dimensional laser microscopic imaging system is established and adopted to detect micron- and submicron-sized defects inside the glass and fiber, and the preparation process is correspondingly optimized to reduce the scattering loss of fibers. The laser energy transmission experiments of fiber laser (wavelength is 2.0 μm) and dual wavelength optical parameter oscillator (OPO) laser (wavelength is 3.8 μm and 4.7 μm) are also carried out. Methods High purity S and As elements are utilized to prepare rod (As40S60) and tube (As39S61). S distilled at 200 ℃ and As sublimed at 350 ℃ are encapsulated in the ampoule and then melted at 750 ℃ for 12 h to obtain preform glasses. Further, hydrogen impurities with the high purity Cl2 are eliminated. Cl2 is introduced into the molten glass and the quantity of flow is 5 ml/min for 300‒600 s. The glass is melted again to allow a reaction between the Cl2 and hydrogen ions. Then the melted product is distilled under a dynamic vacuum to eliminate any gaseous byproducts from the reaction with Cl2. The third step is to eliminate oxygen impurities with elemental aluminum. Al foils with a mass fraction of 0.3% are introduced into the glass and melted at 600 ℃. Oxygen impurities react with Al foils to form Al2O3 which is left on the surface of Al foils, thus obtaining high-purity glasses. The optical fiber is prepared by the rod-in-tube method. The core and cladding diameters are 200 μm/250 μm for multi-mode fiber and 9 μm/140 μm for single-mode fiber, respectively. The single-mode fiber can maintain single-mode transmission in the 3‒5 μm band. The fiber is drawn at about 320 ℃ in a nitrogen-protected environment. The optical fiber loss is measured by the cutback technique and the scattering intensity of the chalcogenide glasses and fibers are examined by a highly sensitive InGaAs detector from the direction perpendicular to the light path (Fig. 4). Results and Discussions The additive amounts of Cl2 are 300, 480, and 600 s, and the samples are recorded as C1, C2, and C3, respectively. The absorption spectra of C1, C2, and C3 samples show that with the increasing Cl2, the absorption intensity at 4.1 μm decreases significantly while the absorption intensity rises gradually at 7.6 μm (Fig. 5). Hydrogen impurities are effectively removed when Cl2 is employed to purify the chalcogenide glasses for reducing the H—S absorption at 4.1 μm. However, more oxygen impurities are also introduced into the glass due to the hydrophility of Cl2, which enhances the absorption intensity of As—O impurities at 7.6 μm. For further elimination of oxygen impurities, aluminum is introduced into the C3 glass, with the sample signed as C3A. The absorption intensity at 7.6 μm decreases significantly and the mass fraction of oxygen impurities reduces from 1.55% to 0.22% (Fig. 6). There is a linear relationship between the mass fraction of oxygen and absorption coefficient at 7.6 μm in chalcogenide glasses (Fig. 7). The striae of the glass is compared for three samples quenched from three different temperatures of 400, 450, and 500 ℃, and the results show that the sample quenched at 450 ℃ has the best uniformity (Fig. 8). The scattering intensity of these three samples also confirms the above conclusions. The gray values of the scattering image for samples quenched at 450 ℃ are more concentrated in the low grade region, which means that the background scattering intensity at 450 ℃ is the lowest (Fig. 9). The fiber attenuation is 0.150 dB/m, 0.087 dB/m at 4.778 μm for C3 and C3A samples respectively (Fig. 11). A laser power output of 6.10 W is obtained in a single-mode fiber when the input power is 12.30 W at 2.0 μm wavelength. The transmission efficiency is about 50%. The output power of 6.12 W is obtained in a multi-mode fiber when the input power is 10.20 W at 3.8 μm and 4.7 μm wavelength. The transmission efficiency is about 59% (Fig. 13). Conclusions The purification technique of chalcogenide glasses is studied. Cl2 is introduced in chalcogenide glasses to eliminate the hydrogen impurities, and the absorption caused by hydrogen impurities decreases with the Cl2 input volume. However, the As—O absorption intensity rises gradually at 7.6 μm, and the absorption coefficient is linearly proportional to the mass fraction of oxygen. The mass fraction of oxygen impurity in the glass is reduced from 1.55% to 0.22% by introducing the reducing agent aluminum. A detection system is set up for examining the defects in the glass using the scattering technique. The glass quenched at 450 ℃ has the least defects. The glass fiber with a loss of 0.087 dB/m (@4.778 μm) is prepared. The output power of 6.10 W is obtained when the input power is 12.30 W at 2.0 μm wavelength for single-mode fiber, and the transmission efficiency is about 50%. Meanwhile, the transmission efficiency is about 59% for multi-mode fiber at 3.8 μm and 4.7 μm wavelength. The laser damage of the end face is mainly caused by the position deviation generated by thermal expansion, which restricts the transmission power of optical fibers. The transmission power of optical fibers is expected to be further improved by adding a fiber cooling system and reducing energy penetration. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20241815997418
• Record 112 of
  
  Title:Robust HDR reconstruction using 3D patch based on two-scale decomposition
  
  Author(s):Qiao, Zhangchi(1,2); Yi, Hongwei(1); Wen, Desheng(1); Han, Yong(1,2,3)
  Source: Signal Processing  Volume: 219  Issue:   DOI: 10.1016/j.sigpro.2024.109384  Published: June 2024  
  Abstract:In this paper, we propose an effective 3D patch-based match and fusion method by taking account of dynamic or multi-view scenes in a multi-exposure image sequence using two-scale decomposition. As opposed to most multi-exposure image fusion methods, the proposed method does not require a pre-alignment step to reduce ghosting artifacts. Considering that pixel values are affected by multi-view or multi-exposure scenes, we use a uniform matching approach to match and find similar patches in different exposure images and then fuse them at each scale. By searching all similar patches (instead of the optimal patch) in the searching window to form the 3D patch when facing limited image information, we can fully use the complementary information of the multi-exposure images to preserve information about moving objects and scene details. The experimental results show that the proposed method not only performs well on dynamic scenes but also consistently generates high-quality fused images in multi-view scenes. © 2024 Elsevier B.V.
  Accession Number: 20240515470150
• Record 113 of
  
  Title:Speckle-correlation-based non-line-of-sight imaging under white-light illumination
  
  Author(s):Zhou, Meiling(1); Zhang, Yang(1,2); Wang, Ping(1,4); Li, Runze(1); Peng, Tong(1); Min, Junwei(1); Yan, Shaohui(1); Yao, Baoli(1,2,3)
  Source: Optics and Laser Technology  Volume: 170  Issue:   DOI: 10.1016/j.optlastec.2023.110231  Published: March 2024  
  Abstract:Non-line-of-sight (NLOS) imaging is attracting extensive attention due to its ability to establish the objects hidden from the direct line-of-sight, which prompts potential applications in autonomous driving, robotic vision, biomedical imaging, and other domains. Various NLOS imaging techniques have been successively demonstrated. In this paper, we propose a speckle-correlation-based method to achieve NLOS imaging under white-light illumination. In the proposed method, we process the raw speckle pattern by incorporating the conventional speckle correlation imaging (SCI) with the Zernike polynomial fitting, named ZPF-SCI method, to enhance the performance of the calculated autocorrelation, a key step to achieve optimal image quality. Experimental results demonstrate that our method is effective even in the presence of ambient light, which circumvents the limitation of the conventional SCI that has to be performed in a darkroom. Furthermore, the proposed ZPF-SCI method is insensitive to the angle that the detector deviates from the vertical plane of the optical axis. The quality of the reconstructed image is still acceptable even if the deviation angle reaches 8 degrees. These superiorities facilitate the practical application of the method. © 2023 Elsevier Ltd
  Accession Number: 20234515010837
• Record 114 of
  
  Title:Modeling of 1.7-μm and 2.4-μm Dual-Wavelength Pumped 4.3-μm Dysprosium-Doped Chalcogenide Fiber Lasers
  
  Author(s):Xiao, Yang(1,2); Cui, Jian(1,2); Xiao, Xusheng(1,2); Xu, Yantao(1,2); Guo, Haitao(1,2)
  Source: IEEE Journal of Quantum Electronics  Volume: 60  Issue: 2  DOI: 10.1109/JQE.2024.3350688  Published: April 1, 2024  
  Abstract:A novel 1.7 μm and 2.4 μm dual-wavelength pumping scheme for a 4.3 μm dysprosium (Dy3+)-doped chalcogenide fiber laser was theoretically demonstrated. It was attributed to the 2.4 μm excited stated absorption (ESA, 6H13/2 ? 6H9/2,6F11/2 transition). Theoretically, when the two pumps were 5 W and 2 W, respectively, a laser power of 1.5 W with an remarkable efficiency of 30.2% was obtained from the homemade Dy3+:Ga0.8As34.2Sb5S60 glass fiber with a loss coefficient of 3 dB/m and a Dy3+ concentration of 3.67 × 1025 ions/m3. Results indicated that the dual-wavelength pumping scheme based on the gain fiber provides a potential way to 4.3 μm dysprosium-doped chalcogenide fiber lasers. © 1965-2012 IEEE.
  Accession Number: 20240315387038
• Record 115 of
  
  Title:Spectroscopic properties and numerical analysis of novel erbium doped multi-component tellurite glasses
  
  Author(s):Wan, Rui(1,2); Guo, Chen(1,2); Li, Xianda(1,2); Wang, Pengfei(1,2)
  Source: Ceramics International  Volume: 50  Issue: 4  DOI: 10.1016/j.ceramint.2023.12.085  Published: February 15, 2024  
  Abstract:In this paper, Er3+ doped TeO2-ZnF2-BaF2-KF-Ta2O5 tellurite glasses with low hydroxyl content (∼0.03 × 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 μm 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 μm was calculated to be 6.4 × 10−21 cm2 and 6.8 × 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. © 2023 Elsevier Ltd and Techna Group S.r.l.
  Accession Number: 20235215291178
• Record 116 of
  
  Title:Observation of three kinds of bound solitons in a black phosphorus-based erbium fiber laser
  
  Author(s):Li, Wenlei(1,2); Lin, Ruping(1); Chen, Guangwei(3); Geng, Gaoli(1); Xu, Peng(1); Yang, Yining(1); Wang, Xinliang(1); Xu, Jian(1)
  Source: Optical Fiber Technology  Volume: 82  Issue:   DOI: 10.1016/j.yofte.2023.103617  Published: January 2024  
  Abstract:We describe the experimental finding of three kinds of bound solitons in the Erbium-doped fiber lasers based on saturable absorber of black phosphorus. The passively mode-locked laser can obtain stretched-pulse state, double-pulse and four-pulse bound state with the sech2-shaped pulse profile. The laser can also realize Lorentzian autocorrelation trace with the duration of approximately 562 fs and deliver Lorentzian double-pulse bound state with pulse separations of approximately 5.04 ps by properly adjusting the polarization state. This project demonstrates that the same fiber laser can obtain different types of bound state pulses, which lays a foundation for further research into bound state pulses. © 2023 Elsevier Inc.
  Accession Number: 20234915153781
• Record 117 of
  
  Title:High refractive index chalcogenide polymer-based planar refractive microlens components
  
  Author(s):Liu, Feng(1); Zhang, Jiawei(1); Guo, Zhaojin(1); Zhou, Liang(1); Li, Xianda(2); Lei, Xiaowei(1); Ji, Ruonan(1); Zhang, Jiwei(1); Li, Peng(1); Liu, Sheng(1); Zhu, Xiangping(2); Zhao, Jianlin(1)
  Source: Optics and Lasers in Engineering  Volume: 178  Issue:   DOI: 10.1016/j.optlaseng.2024.108200  Published: July 2024  
  Abstract:Planar microlens components are highly desired in micro-systems for their compactness and ability to integrate with other planar elements. In this paper, we propose an alternative facile approach to producing positive planar microlens components by infilling concave microlens featured glass encapsulation with high refractive index chalcogenide polymer. The presented refractive microlens components have several advantages: cost-efficient to process, high transmission in broadband spectrum, the ability to generate real focus and real image, and being well-protected by its planar glass encapsulation. Both single and arrayed samples were fabricated to demonstrate the effectiveness of the manufacturing process. The optical properties of the fabricated samples, including phase modulation, imaging performance, and spectrally operational region, were thoroughly characterized. Wavefront calibration with the prepared sample revealed its potential application in practical engineering fields. © 2024 Elsevier Ltd
  Accession Number: 20241415840977
• Record 118 of
  
  Title:Low self-starting threshold polarization-maintaining Er-doped fiber optical frequency comb
  
  Author(s):Gao, Yanwei(1); Cheng, Haihao(2); Hu, Xiaohong(2); Li, Yongqi(1); Liu, Hao(1); Yang, Yanzhao(3); Pan, Ran(2); Wang, Yishan(2); Wu, Shun(1)
  Source: Optics and Laser Technology  Volume: 177  Issue:   DOI: 10.1016/j.optlastec.2024.111092  Published: October 2024  
  Abstract:We report the development of an all-fiber polarization maintaining (PM) optical frequency comb using a mode-locked figure-9 laser with a low self-starting pump threshold. We have achieved self-starting mode-lock for repetition rates (fr) from 70 MHz to 109 MHz. At a repetition rate of 109 MHz, mode-locking can be achieved for a pump power ranging from 187 mW to 880 mW. To the best of our knowledge, this is the lowest pump power reported for PM figure-9 erbium fiber lasers with repetition rate over 100 MHz. By optimizing the pump power to 238 mW, we have achieved an output power of 5 mW, center wavelength of 1566.2 nm, and 3-dB spectral bandwidth of 20.5 nm. The repetition rate has a high signal-to-noise ratio of 95 dB at a resolution bandwidth of 300 Hz. We have studied the spectral characteristics of the laser under different cavity lengths and pump powers. Additionally, we have stabilized the repetition rate using a GPS-Rb disciplined RF reference. The fractional instability of the repetition rate is measured to be 4.67×10-12 at 1 s and 9.22×10-13 at 10 s over a measurement of 11 h. Our findings demonstrate that the developed figure-9 comb is robust, compact and has the advantage of high stability and low power consumption. It offers a cost effective solution for future outdoor comb applications. © 2024
  Accession Number: 20241916030777
• Record 119 of
  
  Title:O-band reconfigurable silicon polarization rotator
  
  Author(s):Bai, Yawen(1,2); Wang, Pengfei(1,2); Peng, Bo(1,2); Chu, Tao(3)
  Source: Chinese Optics Letters  Volume: 22  Issue: 1  DOI: 10.3788/COL202422.011303  Published: January 10, 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. © 2024 Chinese Optics Letters.
  Accession Number: 20241715949098
• Record 120 of
  
  Title:Process optimization of infrared chalcogenide glass based on the scattering detection
  
  Author(s):Tang, Yuxin(1,2); Xu, Yantao(1,2); Cui, Xiaoxia(1,2); Zhang, Jinchang(1,2); Li, Man(3); Xiao, Xusheng(1,2); Yan, Mengmeng(3); Guo, Haitao(1,2,3)
  Source: Ceramics International  Volume: 50  Issue: 5  DOI: 10.1016/j.ceramint.2023.12.020  Published: March 1, 2024  
  Abstract:Chalcogenide glasses with less optical losses are highly demanded as optical materials for micro lense, waveguide and fiber devices. However, it is still challengeable to reduce the optical losses in infrared chalcogenide glasses with opaque visible light. Herein, an improved 3D distribution of scattering sources is established in this study to test and compare the concentration and distribution of defects in As38S62, Ge28Sb12Se60 and As40Se60 chalcogenide glasses. Furthermore, by comparing the scattering images of serial As40Se60 glass prepared under various melting, quenching and annealing temperatures, the preparation process was optimized to reduce its scattering loss. In addition, this study introduced a scheme that could be widely applied to optimize processing of other infrared glasses and devices glass to reduce their scattering losses. © 2023 Elsevier Ltd and Techna Group S.r.l.
  Accession Number: 20235215279498