Contents
2021
Volume: 19 Issue 11
25 Article(s)

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Research Articles
Atomic and Molecular Optics
Molecular orientation induced by H+ collision and modulated with combined fields
Zhiwei Ge, Xuequn Hou, Yu Zhao, and Qingtian Meng
Chinese Optics Letters
  • Publication Date: Oct. 18, 2021
  • Vol.19 Issue, 11 110201 (2021)
Diffraction, Gratings, and Holography
Real-time gradation-expressible amplitude-modulation-type electroholography based on binary-weighted computer-generated hologram
Ren Noguchi, Kohei Suzuki, Yoshiki Moriguchi, Minoru Oikawa, Yuichiro Mori, Takashi Kakue, Tomoyoshi Shimobaba, Tomoyoshi Ito, and Naoki Takada
In amplitude-modulation-type electroholography, the binary-weighted computer-generated hologram (BW-CGH) facilitates the gradation-expressible reconstruction of three-dimensional (3D) objects. To realize real-time gradation-expressible electroholography, we propose an efficient and high-speed method for calculating bit planes consisting of BW-CGHs. The proposed method is implemented on a multiple graphics processing unit (GPU) cluster system comprising 13 GPUs. The proposed BW-CGH method realizes eight-gradation-expressible electroholography at approximately the same calculation speed as that of conventional electroholography based on binary computer-generated holograms. Consequently, we were able to successfully reconstruct a real-time electroholographic 3D video comprising approximately 180,000 points expressed in eight gradations at 30 frames per second.
Chinese Optics Letters
  • Publication Date: Oct. 14, 2021
  • Vol.19 Issue, 11 110501 (2021)
Fiber Optics and Optical Communications
Compensation of turbulence-induced wavefront aberration with convolutional neural networks for FSO systems
Min’an Chen, Xianqing Jin, Shangbin Li, and Zhengyuan Xu
To reduce the atmospheric turbulence-induced power loss, an AlexNet-based convolutional neural network (CNN) for wavefront aberration compensation is experimentally investigated for free-space optical (FSO) communication systems with standard single mode fiber-pigtailed photodiodes. The wavefront aberration is statistically constructed to mimic the received light beams with the Zernike mode-based theory for the Kolmogorov turbulence. By analyzing impacts of CNN structures, quantization resolution/noise, and mode count on the power penalty, the AlexNet-based CNN with 8 bit resolution is identified for experimental study. Experimental results indicate that the average power penalty decreases to 1.8 dB from 12.4 dB in the strong turbulence.
Chinese Optics Letters
  • Publication Date: Aug. 13, 2021
  • Vol.19 Issue, 11 110601 (2021)
Signal transmission of 4 GHz beyond the system bandwidth in UV-C LED communication based on temporal ghost imaging
Mengyin Jin, Zeyuan Qian, Xinwei Chen, Xugao Cui, Ke Jiang, Xiaojuan Sun, Dabing Li, and Pengfei Tian
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 11 110602 (2021)
Gain and laser performance of heavily Er-doped silica fiber fabricated by MCVD combined with the sol-gel method
Qiubai Yang, Yan Jiao, Chunlei Yu, Chongyun Shao, Fengguang Lou, Shikai Wang, Lei Zhang, Qiuhong Yang, and Lili Hu
In this work, a heavily Er-doped fiber with an 8 µm core diameter and a numerical aperture of 0.13 was prepared by the modified chemical vapor deposition (MCVD) technique combined with the sol-gel method. The background loss and absorption coefficient at 1530 nm were measured to be 20 dB/km and 128 dB/m, respectively. Thanks to the sol-gel method, the fiber showed a good doping homogeneity, which was confirmed through unsaturable absorption measurement. The net gains of three 25, 45, and 75-cm-long fibers were measured in the range of 1520 to 1600 nm, and the highest gain reached above 23 dB at both 1530 and 1560 nm in 25 and 75-cm-long fibers, respectively. The short-cavity laser performance was measured using centimeter-scale fibers. The maximum output power of 12 mW was demonstrated in a 6.5-cm-long active fiber with a slope efficiency of 20.4%. Overall, the prepared heavily Er-doped silica fiber is a promising item to be applied in a high-repetition-rate or single-frequency fiber laser.
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 11 110603 (2021)
Multi-distributed probabilistically shaped PAM-4 system for intra-data-center networks
Mengli Liu, Mingyi Gao, and Junchi Ke
Chinese Optics Letters
  • Publication Date: Oct. 12, 2021
  • Vol.19 Issue, 11 110604 (2021)
Imaging Systems and Image Processing
Polarization descattering imaging: a solution for nonuniform polarization characteristics of a target surface
Yi Wei, Pingli Han, Fei Liu, Jinpeng Liu, and Xiaopeng Shao
This paper presents a polarization descattering imaging method for underwater detection in which the targets have nonuniform polarization characteristics. The core of this method takes the nonuniform distribution of the polarization information of the target-reflected light into account and expands the application field of underwater polarization imaging. Independent component analysis was used to separate the target light and backscattered light. Theoretical analysis and proof-of-concept experiments were employed to demonstrate the effectiveness of the proposed method in estimating target information. The proposed method showed superiority in accurately estimating the target information compared with other polarization imaging methods.
Chinese Optics Letters
  • Publication Date: Oct. 26, 2021
  • Vol.19 Issue, 11 111101 (2021)
Lasers, Optical Amplifiers, and Laser Optics
Frequency-modulated continuous-wave dual-frequency LIDAR based on a monolithic integrated two-section DFB laser
Changsheng Wang, Yunshan Zhang, Jilin Zheng, Jin Li, Zhenxing Sun, Jianqin Shi, Lianyan Li, Rulei Xiao, Tao Fang, and Xiangfei Chen
Chinese Optics Letters
  • Publication Date: Sep. 02, 2021
  • Vol.19 Issue, 11 111402 (2021)
Adjustable-free and movable Nd:YVO4 thin disk laser based on the telecentric cat’s eye cavity | Editors' Pick
Wei Wang, Yongxi Gao, Di Sun, Xiao Du, Jie Guo, and Xiaoyan Liang
In this paper, we propose and demonstrate an adjustable-free and movable Nd:YVO4 thin disk laser based on the telecentric cat’s eye cavity. We design a V-shaped laser cavity containing two reflectors with Nd:YVO4 thin disks as the gain medium. The experimental results from the traditional plane-plane cavity, plane-telecentric cat’s eye cavity, and double telecentric cat’s eye cavity are compared. They show that plane-telecentric cat’s eye cavity laser can keep operating at the adjustable-free range of -6° to +6°, which is up to 60 times better than that of traditional plane-plane cavity. In the double telecentric cat’s eye case, the adjustable-free range is improved to -13° to +13°. Additionally, in the case of the double telecentric cat’s eye cavity, the output telecentric cat’s eye can achieve free movement within the horizontal range of ±20 mm.
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 11 111403 (2021)
Simultaneous tailoring of longitudinal and transverse mode inside an Er:YAG laser
Rui Song, Xueting Liu, Shiyao Fu, and Chunqing Gao
In this paper, we demonstrate a scheme to tailor both longitudinal and transverse modes inside a laser cavity and constitute an eye-safe single longitudinal mode Er:Y3Al5O12 (Er:YAG) vector laser. A q-plate is employed as a spin-orbital conversion element to modulate the transverse mode and obtain cylindrical vector beams. An optical isolator is employed as a non-reciprocal element for the ring cavity to enforce unidirectional operation and achieve single longitudinal oscillation. The characteristics of power, transverse intensity, and polarization spectrum of the output beams are observed. The observed typical single longitudinal mode and highly matched special polarizations prove the successful tailoring of both longitudinal and transverse modes.
Chinese Optics Letters
  • Publication Date: Sep. 09, 2021
  • Vol.19 Issue, 11 111404 (2021)
Switchable single- and dual-wavelength femtosecond mode-locked Er-doped fiber laser based on carboxyl-functionalized graphene oxide saturable absorber
Qimeng Lin, Li Yan, Yuanqi Song, Xuzhuo Jia, Xiaoqiang Feng, Lei Hou, and Jintao Bai
Chinese Optics Letters
  • Publication Date: Oct. 22, 2021
  • Vol.19 Issue, 11 111405 (2021)
Microwave Photonics
Linearized wideband and multi-carrier link based on TL-ANN
Enji Liu, Zhenming Yu, Zhiquan Wan, Liang Shu, Kaixuan Sun, Lili Gui, and Kun Xu
The analog photonics link (APL) is widely used in microwave photonics. However, in wideband and multi-carrier systems, the third inter-modulation distortion (IMD3) and cross-modulation distortion (XMD) will jointly limit the spurious-free dynamic range (SFDR) of links. In this paper, we experimentally present a linearized wideband and multi-carrier APL, in which the IMD3 and XMD are mitigated simultaneously by using artificial neural networks with transfer learning (TL-ANN). In this experiment, with different artificial neural networks, which are trained with the knowledge obtained from the two- or three-sub-carrier system, the IMD3 and XMD are suppressed by 21.71 dB and 11.11 dB or 22.38 dB and 16.73 dB, and the SFDR is improved by 13.4 dB or 14.3 dB, respectively. Meanwhile, compared with previous studies, this method could reduce the training time and training epochs to 16% and 25%.
Chinese Optics Letters
  • Publication Date: Sep. 02, 2021
  • Vol.19 Issue, 11 113901 (2021)
Nonlinear Optics
All-optical carrier recovery for self-homodyne detection via injection locked Brillouin laser in whispering-gallery-mode microcavity
Boyuan Liu, Yong Geng, Qiang Zhang, Xinjie Han, Jing Xu, Heng Zhou, and Kun Qiu
We demonstrate comprehensive investigation of the injection locking dynamics of a backscattered Brillouin laser in silica whispering-gallery-mode microcavity. Via injection locking, the Brillouin laser acquires highly correlated phase with the seed laser, enabling ultra-narrow bandwidth, high gain, and coherent optical amplification. Also, for the first time, to the best of our knowledge, the injection locked Brillouin laser is utilized to implement all-optical carrier recovery from coherent optical data signals. We show that by using the injection locked Brillouin laser as a local oscillator for self-homodyne detection, high-quality data receiving can be realized, even without traditional electrical compensations for carrier frequency and phase drifts.
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 11 111901 (2021)
Vector dynamics of ultrafast cylindrical vector beams in a mode-locked fiber laser
Jiazhu Wang, Liang Jin, Shangzhi Xie, Renyan Wang, He Zhang, Yingtian Xu, Xin Zhao, Yan Li, and Xiaohui Ma
The vector dynamics of solitons are crucial but easily neglected for realizing vortex solitons. In this Letter, we investigate the effect of vector dynamics on cylindrical vector beams (CVBs) implementation and propose a novel technical method to realize femtosecond CVBs based on vector-locked solitons, which are presented as group-velocity-locked vector solitons (GVLVSs) in the experiment. The outstanding vector properties of GVLVSs not only greatly improve the efficiency of solitons converted into CVBs and output power of CVBs (2.4 times and 4.1 times that of scalar solitons and vector change periodical solitons, with the purity of 97.2%), but also relax the obstacle of ultrafast CVBs from the fundamental frequency to the harmonic regime (up to 198 MHz) for the first time, to the best of our knowledge. This is the highest repetition rate reported for ultrafast CVBs based on passive mode-locking. The investigation of the influence of solitons vector dynamics evolution on the realization of CVBs provides guidance for the excellent performance of ultrafast CVBs.
Chinese Optics Letters
  • Publication Date: Oct. 25, 2021
  • Vol.19 Issue, 11 111903 (2021)
Optical Design and Fabrication
Design of multi-passband polymer multilayer film and its application in photovoltaic agriculture
Ming Li, Yang Liu, Fangxin Zhang, Xinyu Zhang, Zhisen Zhang, Altyeb Ali Abaker Omer, Shutao Zhao, and Wen Liu
Chinese Optics Letters
  • Publication Date: Aug. 03, 2021
  • Vol.19 Issue, 11 112201 (2021)
Optical design of a compact and high-transmittance compressive sensing imaging system enabled by freeform optics
Dewen Cheng, Hailong Chen, Tong Yang, Jun Ke, Yang Li, and Yongtian Wang
Chinese Optics Letters
  • Publication Date: Sep. 01, 2021
  • Vol.19 Issue, 11 112202 (2021)
Optical Materials
Mid-infrared flat-topped broadband chiral helix metamaterials based on indium tin oxide and their chiral properties
Wentao Zhang, Weijie Shi, Hui Guo, and Changchun Yan
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 11 111601 (2021)
Physical Optics
Liquid crystal devices for vector vortex beams manipulation and quantum information applications [Invited] | Editors' Pick
Zhi-Xiang Li, Ya-Ping Ruan, Peng Chen, Jie Tang, Wei Hu, Ke-Yu Xia, and Yan-Qing Lu
Chinese Optics Letters
  • Publication Date: Oct. 18, 2021
  • Vol.19 Issue, 11 112601 (2021)
Quantum Optics and Quantum Information
Sequential 3 → 1 quantum random access code utilizing unsharp measurements
Zhiguang Pang, Jiang Gao, Tianlei Hou, Min Wei, Jian Li, and Qin Wang
Chinese Optics Letters
  • Publication Date: Sep. 02, 2021
  • Vol.19 Issue, 11 112701 (2021)
Solar Energy and Photovoltaics
Incorporation of Ag into Cu(In,Ga)Se2 films in low-temperature process
Zhaojing Hu, Yunxiang Zhang, Shuping Lin, Shiqing Cheng, Zhichao He, Chaojie Wang, Zhiqiang Zhou, Fangfang Liu, Yun Sun, and Wei Liu
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 11 114001 (2021)
Reviews
Biophotonics
Review of photoacoustic imaging for microrobots tracking in vivo [Invited] | On the Cover
Dengfeng Li, Yachao Zhang, Chao Liu, Jiangbo Chen, Dong Sun, and Lidai Wang
Microrobots-assisted drug delivery and surgery have been always in the spotlight and are highly anticipated to solve the challenges of cancer in situ treatment. These versatile small biomedical robots are expected to realize direct access to the tumor or disease site for precise treatment, which requires real-time and high-resolution in vivo tracking as feedback for the microrobots’ actuation and control. Among current biomedical imaging methods, photoacoustic imaging (PAI) is presenting its outstanding performances in the tracking of microrobots in the human body derived from its great advantages of excellent imaging resolution and contrast in deep tissue. In this review, we summarize the PAI techniques, imaging systems, and their biomedical applications in microrobots tracking in vitro and in vivo. From a robotic tracking perspective, we also provide some insight into the future of PAI technology in clinical applications.
Chinese Optics Letters
  • Publication Date: Sep. 06, 2021
  • Vol.19 Issue, 11 111701 (2021)
Nonlinear Optics
Performance comparison of lithium-niobate-based extremely high-field single-cycle terahertz sources [Invited] | Editors' Pick
György Tóth, László Pálfalvi, Szabolcs Turnár, Zoltán Tibai, Gábor Almási, and János Hebling
Tilted-pulse-front-pumping (TPFP) lithium-niobate terahertz (THz) pulse sources are widely used in pump-probe and control experiments since they can generate broadband THz pulses with tens of microjoules of energy. However, the conventional TPFP setup suffers from limitations, hindering the generation of THz pulses with peak electric field strength over 1 MV/cm. Recently, a few setups were suggested to mitigate or even eliminate these limitations. In this paper, we shortly review the setups that are suitable for the generation of single-cycle THz pulses with up to a few tens of megavolts/centimeter focused electric field strength. The THz pulses available with the new layouts pave the way for previously unattainable applications that require extremely high electric field strength and pulse energy in the multi-millijoule range.
Chinese Optics Letters
  • Publication Date: Sep. 02, 2021
  • Vol.19 Issue, 11 111902 (2021)