Contents 3 Issue (s), 40 Article (s)

Vol. 20, Iss.12—Dec.1, 2022 • pp: 120201- Spec. pp:

Vol. 20, Iss.11—Nov.1, 2022 • pp: 110501- Spec. pp:

Vol. 20, Iss.10—Oct.1, 2022 • pp: 100002- Spec. pp:

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Research ArticlesVol. 20, Iss.12-Dec..1,2022
Atomic and Molecular Optics
Frequency control of a lattice laser at 759 nm by referencing to Yb clock transition at 578 nm
Yaqin Hao, Yuan Yao, Haosen Shi, Hongfu Yu, Yanyi Jiang, and Longsheng Ma
Chinese Optics Letters
  • Publication Date: Sep. 23, 2022
  • Vol. 20, Issue 12, 120201 (2022)
Diffraction, Gratings, and Holography
Generating large topological charge Laguerre–Gaussian beam based on 4K phase-only spatial light modulator
Ruijian Li, Yuan Ren, Tong Liu, Chen Wang, Zhengliang Liu, Jie Zhao, Rusheng Sun, and Ziyang Wang
The resolution of the spatial light modulator (SLM) screen and the encoding algorithm of the computer-generated hologram are the primary limiting factors in the generation of large topological charge vortex beams. This paper attempts to solve these problems by improving both the hardware and the algorithm. Theoretically, to overcome the limitations of beam waist radius, the amplitude profile function of large topological charge Laguerre–Gaussian (LG) beam is properly improved. Then, an experimental system employing a 4K phase-only SLM is set up, and the LG beams with topological charge up to 1200 are successfully generated. Furthermore, we discuss the effect of different beam waist radii on the generation of LG beams. Additionally, the function of the LG beam is further improved to generate an LG beam with a topological charge as high as 1400. Our results set a new benchmark for generating large topological charge vortex beams, which can be widely used in precise measurement, sensing, and communication.
Chinese Optics Letters
  • Publication Date: Aug. 10, 2022
  • Vol. 20, Issue 12, 120501 (2022)
Imaging Systems and Image Processing
End-to-end optimization of a diffractive optical element and aberration correction for integral imaging
Xiangyu Pei, Xunbo Yu, Xin Gao, Xinhui Xie, Yuedi Wang, Xinzhu Sang, and Binbin Yan
In the integral imaging light field display, the introduction of a diffractive optical element (DOE) can solve the problem of limited depth of field of the traditional lens. However, the strong aberration of the DOE significantly reduces the final display quality. Thus, herein, an end-to-end joint optimization method for optimizing DOE and aberration correction is proposed. The DOE model is established using thickness as the variable, and a deep learning network is built to preprocess the composite image loaded on the display panel. The simulation results show that the peak signal to noise ratio value of the optimized image increases by 8 dB, which confirms that the end-to-end joint optimization method can effectively reduce the aberration problem.
Chinese Optics Letters
  • Publication Date: Aug. 05, 2022
  • Vol. 20, Issue 12, 121101 (2022)
Instrumentation, Measurement, and Optical Sensing
Multifunctional single-fiber optical tweezers for particle trapping and transport
Hao Wu, Chunlei Jiang, Shaopeng Tian, Shangzhao Shao, Hangyu Yue, Xiangyu Cui, Bingkun Gao, Xiufang Wang, and Peng Chen
Chinese Optics Letters
  • Publication Date: Sep. 22, 2022
  • Vol. 20, Issue 12, 121201 (2022)
Integrated Optics
High-performance millimeter-scale silicon grating emitters for beam steering applications
Ze Chen, Haibin Lü, Yanfeng Chen, and Xiaoping Liu
A 2-mm-long silicon-on-insulator grating emitter with a narrow angular full width at half-maximum (FWHM) and a high sideband suppression ratio (SSR) is proposed and designed. It consists of a Si3N4/Si grating with an approximate Gaussian emission profile along the grating length, which aims to reduce the sidelobe intensity of the scanning light in the far-field, thereby improving the resolution of the longitudinal steering resolution of the light detection and ranging (lidar). Numerical analysis shows that the angular FWHM of the emitted beam could be as low as 0.026° for a grating length of 2.247 mm and the input TE-like waveguide mode at 1550 nm, and the SSR could be more than 32.622 dB. Moreover, this Si3N4/Si grating exhibits a favorable fabrication error tolerance when considering the width and length variation of the Si3N4 overlayer in practice. Our design offers a promising platform for realizing integrated optical phased arrays for the long-distance solid-state lidar.
Chinese Optics Letters
  • Publication Date: Sep. 28, 2022
  • Vol. 20, Issue 12, 121301 (2022)
Lasers, Optical Amplifiers, and Laser Optics
Continuous-wave π-polarized 1084 nm laser based on Nd:MgO:LiNbO3 under 888 nm thermally boosted pumping
Rui Zhao, Xiaotian Lei, Xiaodai Yao, Yue Lu, Yongji Yu, and Guangyong Jin
A continuous-wave (CW) π-polarized 1084 nm laser based on Nd:MgO:LiNbO3 under 888 nm thermally boosted pumping is reported. According to the absorption spectrum and energy level structure of Nd:MgO:LiNbO3, the 888 nm laser diode (LD) is used for thermally boosted pumping. This pumping method eliminates the quantum defect caused by the nonradiative transition in Nd:MgO:LiNbO3 under the traditional 813 nm pumping and effectively improves the serious thermal effect of the crystal. The unmatched polarized 1093 nm laser is completely suppressed, and the π-polarized laser output of 1084 nm in the whole pump range is realized by the 888 nm thermally boosted pumping. In the present work, we achieved the CW π-polarized 1084 nm laser with a maximum output power of 7.53 W and a slope efficiency of about 46.1%.
Chinese Optics Letters
  • Publication Date: Sep. 23, 2022
  • Vol. 20, Issue 12, 121401 (2022)
Nanophotonics, Metamaterials, and Plasmonics
High-efficiency monolayer metallic metasurface for modulation of orbital angular momentum
Peijun Liu, Yanan Fu, Xi Xie, Changjun Min, Yuquan Zhang, and Xiaocong Yuan
Chinese Optics Letters
  • Publication Date: Jul. 12, 2022
  • Vol. 20, Issue 12, 123601 (2022)
Optical Design and Fabrication
Laser emission from low-loss cladding waveguides in Pr:YLF by femtosecond laser helical inscription
Yingying Ren, Zemeng Cui, Lifei Sun, Chao Wang, Hongliang Liu, and Yangjian Cai
Chinese Optics Letters
  • Publication Date: Aug. 30, 2022
  • Vol. 20, Issue 12, 122201 (2022)
Optical Materials
Crystal growth and spectral properties of (Yb0.15Lu0.85xY0.85-0.85x)3Al5O12 single crystals
Ruifeng Tian, Mingyan Pan, Lu Zhang, and Hongji Qi
Chinese Optics Letters
  • Publication Date: Aug. 05, 2022
  • Vol. 20, Issue 12, 121601 (2022)
Physical Optics
Symmetry detection of rotating patterns based on rotational Doppler effect of light
Fang Han, Weijie Wang, Tong Liu, Yuan Ren, Zhengliang Liu, and Song Qiu
Chinese Optics Letters
  • Publication Date: Aug. 09, 2022
  • Vol. 20, Issue 12, 122601 (2022)
Quantum Optics and Quantum Information
Phase modulation polarization encoding module applied to one-to-many QKD network based on wavelength division multiplexing
Yi Zhang, Xiaojuan Qin, Jindong Wang, Yafei Yu, Zhengjun Wei, and Zhiming Zhang
The quantum key distribution (QKD) network is a promising solution for secure communications. In this paper, we proposed a polarization-independent phase-modulated polarization encoding module, and it can be combined with a dense wavelength division multiplexer (DWDM) to achieve multi-user QKD. We experimentally test the encoding module with a repetition rate of 62.5 MHz, and its average quantum bit error rate (QBER) is as low as 0.4%. Finally, we implement a principle verification test for simultaneous QKD for 1 to 2 users in 100 min, and the average QBER of two users under the transmission distance of 1 km and 5 km is kept below 0.8%. Due to the use of polarization encoding, the module can also realize scalable network architecture in free-space QKD systems in the future.
Chinese Optics Letters
  • Publication Date: Aug. 15, 2022
  • Vol. 20, Issue 12, 122701 (2022)
Quantum Optics and Quantum Information
Fabrication, testing, and assembly of high-finesse optical fiber microcavity for molecule cavity QED experiment
Yuhao Pan, Li Li, Xiaolong Zhou, Dongyu Huang, Zemin Shen, Jian Wang, Chuanfeng Li, and Guangcan Guo
The ultracold molecule is a promising candidate for versatile quantum tasks due to its long-range interaction and rich internal rovibrational states. With the help of the cavity quantum electrodynamics (QED) effects, an optical cavity can be employed to increase the efficiency of the formation of the photoassociated molecules and offers a non-demolition detection of the internal states of molecules. Here, we demonstrate the production of the high-finesse optical fiber microcavity for the Rb2 molecule cavity QED experiment, which includes the fabrication of fiber-based cavity mirrors, testing, and the assembly of ultra-high vacuum-compatible optical fiber microcavity. The optical fiber microcavity offers high cooperativity between cavity mode and ultracold molecule and paves the way for the study of molecule cavity QED experimental research.
Chinese Optics Letters
  • Publication Date: Aug. 15, 2022
  • Vol. 20, Issue 12, 122702 (2022)
Research ArticlesVol. 20, Iss.11-Nov..1,2022
Diffraction, Gratings, and Holography
Measuring the topological charge of optical vortices with a single plate
Jingyin Zhao, Yunxia Jin, Fanyu Kong, Dongbing He, Hongchao Cao, Wang Hao, Yubo Wu, and Jianda Shao
Measuring the topological charge (TC) of optical vortex beams by the edge-diffraction pattern of a single plate is proposed and demonstrated. The diffraction fringes can keep well discernible in a wide three-dimensional range in this method. The redundant fringes of the diffracted fork-shaped pattern in the near-field can determine the TC value, and the orientation of the fork tells the handedness of the vortex. The plate can be opaque or translucent, and the requirement of the translucent plate for TC measurement is analyzed. Measurement of TCs up to ±40 is experimentally demonstrated by subtracting the upper and lower fringe numbers with respect to the center of the light. The plate is easy to get, and this feasible measurement can bring great convenience and efficiency for researchers.
Chinese Optics Letters
  • Publication Date: Jun. 26, 2022
  • Vol. 20, Issue 11, 110501 (2022)
Fiber Optics and Optical Communications
Security enhancement for OFDM-UWOC system using three-layer chaotic encryption and chaotic DFT precoding
Huan Deng, Zihao Du, Jianmin Xiong, Xingqi Yang, Yan Hua, and Jing Xu
Chinese Optics Letters
  • Publication Date: Jul. 05, 2022
  • Vol. 20, Issue 11, 110601 (2022)
Fiber Optics and Optical Communications
Visible light communication system at 3.59 Gbit/s based on c-plane green micro-LED
Guoqiang Li, Runze Lin, Haichao Guo, Pengfei Tian, and Nan Chi
Visible light communication (VLC) based on the micro light emitting diode (micro-LED) has attracted increasing attention owing to its high bandwidth, low power consumption, and high security. Compared with semi-polar or non-polar micro-LEDs, the commercial polar micro-LED has the advantages of low cost and more mature epitaxy technique. In this study, green micro-LEDs with different indium tin oxide (ITO) sizes are fabricated based on the commercial c-plane LED epitaxial wafer. The transmission performance of 80, 100, and 150 µm devices has been studied in detail. A partial pre-equalization scheme is utilized to increase data rates. Finally, the VLC system with a 100 µm green micro-LED as the transmitter could achieve a maximum data rate of 3.59 Gbit/s. Such a result will be beneficial to promote the further development of low-cost, high-speed VLC devices in the future.
Chinese Optics Letters
  • Publication Date: Jul. 14, 2022
  • Vol. 20, Issue 11, 110602 (2022)
Infrared and Terahertz Photonics
Inversely-designed terahertz metadevice with ultrafast modulation of double electromagnetically induced transparency windows
Siyang Hu, Cheng Xiang’ai, Weibao He, Yuze Hu, Mingyu Tong, and Zhongjie Xu
Terahertz metasurfaces have great applications for efficient terahertz modulation, but there are still problems in designing terahertz metadevices in terms of complexity and inefficiency. Herein, we demonstrate an inversely-designed terahertz metasurface with double electromagnetically induced transparency (EIT)-like windows by incorporating a particle swarm optimization (PSO) algorithm with the finite-difference time-domain method. We prepared and tested the metadevices, and the experimental terahertz signals are close to the designed results. By hybridizing amorphous germanium film with the inversely-designed metasurface, two EIT-like windows, including transmission and slow-light effect, exhibit ultrafast modulation behavior in 25 ps excited by a femtosecond laser. The modulation depths of transmission in two transparency windows are 74% and 65%, respectively. The numerical simulations also illustrate the ultrafast dynamic process and modulation mechanism, which match well with the experiment results. Our work thus offers opportunities for designing other objective functions of the terahertz metadevice.
Chinese Optics Letters
  • Publication Date: Jul. 13, 2022
  • Vol. 20, Issue 11, 113701 (2022)
Instrumentation, Measurement, and Optical Sensing
Improving the sensitivity of DC magneto-optical Kerr effect measurement to 10−7rad/Hz
Junying Ma, Feng Gu, Ying Xu, Jiaming Le, Fanlong Zeng, Yizheng Wu, and Chuanshan Tian
Chinese Optics Letters
  • Publication Date: Jul. 14, 2022
  • Vol. 20, Issue 11, 111201 (2022)
Integrated Optics
Fabrication and characterization of on-chip silicon spherical-like microcavities with high Q-factors
Hailong Han, Hao Li, Lixing You, and Xiaoping Liu
Chinese Optics Letters
  • Publication Date: Jul. 13, 2022
  • Vol. 20, Issue 11, 111301 (2022)
Lasers, Optical Amplifiers, and Laser Optics
Intense, wideband optical waveform generation by self-balanced amplification of fiber electro-optical sideband modulation
Yuzhuo Wang, Yizun He, Lingjing Ji, Jiangyong Hu, Xing Huang, Yudi Ma, Liyang Qiu, Kaifeng Zhao, and Saijun Wu
We demonstrate a simple method to obtain accurate optical waveforms with a gigahertz-level programmable modulation bandwidth and a watt-level output power for wideband optical control of free atoms and molecules. Arbitrary amplitude and phase modulations are transferred from microwave to light with a low-power fiber electro-optical modulator. The sub-milliwatt optical sideband is co-amplified with the optical carrier in a power-balanced fashion through a tapered semiconductor amplifier (TSA). By automatically keeping TSA near saturation in a quasi-continuous manner, typical noise channels associated with pulsed high-gain amplifications are efficiently suppressed. As an example application, we demonstrate interleaved cooling and trapping of two rubidium isotopes with coherent nanosecond pulses.
Chinese Optics Letters
  • Publication Date: Jul. 06, 2022
  • Vol. 20, Issue 11, 111401 (2022)
Light-Matter Interaction
High-fidelity parametric amplification of Ince–Gaussian beams
Ding Yan, Zhiyuan Zhong, Tong Qi, Hongying Chen, and Wei Gao
Ince–Gaussian (IG) beams, as eigenfunctions of the paraxial wave equation in elliptical coordinates, are attracting increasing interest owing to their propagation-invariant and full-field properties. Optical amplification via parametric interactions can further expand their application areas, yet it is rarely studied. In this work, we report on a high-fidelity parametric amplifier for IG beams. The nonlinear transformation of the spatial spectra of the signal and associated influences on the beam profiles of the amplified signal, under different pump structures, were theoretically and experimentally investigated. By using a perfect flattop beam as the pump, we show that the transverse structure of IG signals is well maintained, and the distortion induced by radial-mode degeneration is overcome during amplification. This proof-of-principle demonstration paves the way for a mode-independent and distortion-free amplifier of arbitrary structured light and has great significance in relevant areas, such as quantum optics, tunable infrared-laser generation, and image amplification.
Chinese Optics Letters
  • Publication Date: Jul. 14, 2022
  • Vol. 20, Issue 11, 113801 (2022)
Microwave Photonics
Weak RF signal detection with high resolution and no blind zone based on ultra-simple multi-mode optoelectronic oscillation
Xin Zhang, Tao Pu, Yunshan Zhang, Hua Zhou, Lin Lu, Jin Li, Xiangfei Chen, and Jilin Zheng
Weak RF signal detection with high resolution and no blind zone based on directly modulated multi-mode optoelectronic oscillation has been proposed. The high-sensitivity optical modulators and optical filters are avoided because multi-mode oscillation is obtained based on directly modulating the semiconductor laser at the relaxation oscillation frequency. For the directly modulated optoelectronic oscillator, the detection characteristics such as gain for the RF signal, resolution, noise floor, and sensitivity are firstly analyzed. The experimental results are consistent with the simulated results. For the RF signal of unknown frequency, it can be detected out and amplified by tuning the bias current and delay time of the loop. There is no blind zone within 1–4.5 GHz. The system provides a maximum gain of 17.88 dB for the low-power RF signal. The sensitivity of the system can reach as high as -95 dBm. The properties such as gain dynamic range and power stability are also investigated. The system has potential for weak RF signal detection, especially for the RF signal with unknown frequency.
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 11, 113901 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Fast dual-beam alignment method for stimulated emission depletion microscopy using aggregation-induced emission dye resin
Miao Zhao, Fengming Liu, Yang Yu, Xinjun Guo, Hao Ruan, and Jing Wen
A stimulated emission depletion is capable of breaking the diffraction limit by exciting fluorescent molecules with a solid Gaussian beam and quenching the excited molecules with another donut beam through stimulated emission. The coincidence degree of these two beams in three dimensions will significantly influence the spatial resolution of the microscope. However, the conventional alignment approach based on raster scanning of gold nanoparticles by the two laser beams separately suffers from a mismatch between fluorescence and scattering modes. To circumvent the above problems, we demonstrate a fast alignment design by scanning the second beam over the fabricated sample, which is made of aggregation-induced emission (AIE) dye resin. The relative positions of solid and donut laser beams can be represented by the fluorescent AIE from the labeled spots in the dye resin. This design achieves ultra-high resolutions of 22 nm in the x/y relative displacement and 27 nm in the z relative displacement for fast spatial matching of the two laser beams. This study has potential applications in scenarios that require the spatial matching of multiple laser beams, and the field of views of different objectives, for example, in a microscope with high precision.
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 11, 113601 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Fabrication of lithium niobate metasurfaces via a combination of FIB and ICP-RIE
Chunyan Jin, Wei Wu, Lei Cao, Bofeng Gao, Jiaxin Chen, Wei Cai, Mengxin Ren, and Jingjun Xu
Lithium niobate (LN) metasurfaces have emerged as a new platform for manipulating electromagnetic waves. Here, we report a fabrication technique for LN nano-grating metasurfaces by combining focused ion beam (FIB) milling with inductively coupled plasma reactive ion etching (ICP-RIE). Steep sidewalls with angles larger than 80° are achieved. Sharp quasi-bound states in the continuum are observed from our metasurfaces. The measured transmission spectra show good agreement with the numerical simulations, confirming the high quality of the fabricated metasurfaces. Our technique can be applied to fabricate the LN metasurfaces with sharp resonances for various applications in optical communications, on-chip photonics, laser physics, sensing, and so on.
Chinese Optics Letters
  • Publication Date: Jul. 12, 2022
  • Vol. 20, Issue 11, 113602 (2022)
Nonlinear Optics
Interactions of the second-order solitons with an external probe pulse in the optical event horizon
Jifang Rong, Yiwu Ma, Meng Xu, and Hua Yang
We demonstrate manipulating the interactions of a second-order soliton with a weak probe pulse under the condition of group velocity match and group velocity mismatch (GVMM). During these interactions, the second-order soliton acting as an effective periodic refractive-index barrier leads to the polychromatic scattering of the probe pulse, which is represented as unequally spaced narrow-band sources with adjustable spectral width. In the case of GVMM, almost all the spectral components of the narrow-band sources meet the nonlinear frequency conversion relationship by using the wavenumber-matching relationship due to the robustness of the second-order soliton under moderate high-order-dispersion perturbations, so this case is more conducive to the study of the soliton wells. In addition, different transmission states of a soliton well are demonstrated under different probe pulse properties in the fiber-optical analog of the event horizon. When the power of the probe pulse is strong enough, a dispersive wave can be generated from the collision of two fundamental solitons split from the two second-order solitons. These interesting phenomena investigated in this work as a combination of white- and black-hole horizons can be considered as promising candidates for frequency conversion and broadband supercontinuum generation.
Chinese Optics Letters
  • Publication Date: Jul. 13, 2022
  • Vol. 20, Issue 11, 111901 (2022)
Nonlinear Optics
Sum-frequency generation of a laser and its background in an on-chip lithium-niobate microdisk
Zhenzhong Hao, Li Zhang, Jie Wang, Fang Bo, Feng Gao, Guoquan Zhang, and Jingjun Xu
Chinese Optics Letters
  • Publication Date: Jul. 14, 2022
  • Vol. 20, Issue 11, 111902 (2022)
Optoelectronics
Progress on photovoltaic AlGaN photodiodes for solar-blind ultraviolet photodetection
Xu Liu, and Shengjun Zhou
Solar-blind ultraviolet photodetectors (SBPDs) have attracted tremendous attention in the environmental, industrial, military, and biological fields. Aluminum gallium nitride (AlGaN), a kind of representative III-nitride semiconductor, has promising prospects in solar-blind photodetection owing to its tunable wide bandgap and industrial feasibility. Considering the high defect density in the AlGaN epilayer directly grown on a sapphire substrate, employing an AlN/sapphire template turns out to be an effective method to achieve a high-quality AlGaN epilayer, thereby enhancing the SBPD performances. In recent years, a variety of remarkable breakthroughs have been achieved in the SBPDs. In this paper, the progress on photovoltaic AlGaN-based SBPDs is reviewed. First, the basic physical properties of AlGaN are introduced. Then, fabrication methods and defect annihilation of the AlN/sapphire template are discussed. Various photovoltaic SBPDs are further summarized, including Schottky barrier, metal-semiconductor-metal, p-n/p-i-n and avalanche photodiodes. Furthermore, surface modification and photoelectrochemical cell techniques are introduced. Benefitting from the development of fabrication techniques and optoelectronic devices, photovoltaic AlGaN photodiodes exhibit a promising prospect in solar-blind ultraviolet photodetection.
Chinese Optics Letters
  • Publication Date: Aug. 10, 2022
  • Vol. 20, Issue 11, 112501 (2022)
Physical Optics
High-speed three-dimensional shape measurement with inner shifting-phase fringe projection profilometry
Shichao Yang, Hanlin Huang, Gaoxu Wu, Yanxue Wu, Tian Yang, and Fei Liu
Fringe projection profilometry (FPP) has been extensively studied in the field of three-dimensional (3D) measurement. Although FPP always uses high-frequency fringes to ensure high measurement accuracy, too many patterns are projected to unwrap the phase, which affects the speed of 3D reconstruction. We propose a high-speed 3D shape measurement method using only three high-frequency inner shifting-phase patterns (70 periods), which satisfies both high precision and high measuring speed requirements. Besides, our proposed method obtains the wrapped phase and the fringe order simultaneously without any other information and constraints. The proposed method has successfully reconstructed moving objects with high speed at the camera’s full frame rate (1700 frames per second).
Chinese Optics Letters
  • Publication Date: Jul. 13, 2022
  • Vol. 20, Issue 11, 112601 (2022)
Research ArticlesVol. 20, Iss.10-Oct..1,2022
Fiber Optics and Optical Communications
Portable system integrated with time comparison, ranging, and communication
Qiongqiong Zhang, Chengkai Pang, Yurong Wang, Guangyue Shen, Lei Yang, Zhaohui Li, Haiyan Huang, and Guang Wu
We demonstrate a portable system integrated with time comparison, absolute distance ranging, and optical communication (TRC) to meet the requirements of space gravitational wave detection. A 1 km free-space asynchronous two-way optical link is performed. The TRC realizes optical communication with 7.7×10-5 bit error rate with a Si avalanche photodiode single-photon detector, while the signal intensity is 1.4 photons per pulse with the background noise of 3×104 counts per second. The distance measurement uncertainty is 48.3 mm, and time comparison precision is 162.4 ps. In this TRC system, a vertical-cavity surface-emitting laser diode with a power of 9.1 µW is used, and the equivalent receiving aperture is 0.5 mm. The TRC provides a miniaturization solution for ultra-long distance inter-satellite communication, time comparison, and ranging for space gravitational wave detectors.
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 100601 (2022)
Fiber Optics and Optical Communications
High gain E-band amplification based on the low loss Bi/P co-doped silica fiber
Jinmin Tian, Mengting Guo, Fan Wang, Chunlei Yu, Lei Zhang, Meng Wang, and Lili Hu
A home-made low loss Bi/P co-doped silica fiber was fabricated using the modified chemical vapor deposition (MCVD) technique combined with the solution doping method, where the background loss at 1550 nm was as low as 17 dB/km. We demonstrated for the first time, to the best of our knowledge, an all-fiber amplifier using the home-made Bi/P co-doped fiber achieving broadband amplification in the E-band. The amplifying performance was evaluated and optimized with different pumping patterns and fiber length. A maximum net gain at 1355 nm close to 20 dB and a minimum noise figure of 4.6 dB were obtained for the first time, to the best of our knowledge, using two 1240 nm laser diodes under bidirectional pumping with the input pump and signal powers of 870 mW and -30 dBm, respectively.
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 100602 (2022)
Integrated Optics
Experimental investigation on the unbalanced Mach–Zehnder interferometer on lithium niobate thin film
Xuerui Sun, Yinan Wu, Chuanyi Lu, Yuting Zhang, Hao Li, Shijie Liu, Yuanlin Zheng, and Xianfeng Chen
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 101301 (2022)
Microwave Photonics
Delivery of 40 Gbit/s W-band signal over 4600 m wireless distance employing advanced digital signal processing
Bowen Zhu, Yanyi Wang, Weiping Li, Feng Wang, Jiaxuan Liu, Miao Kong, and Jianjun Yu
Chinese Optics Letters
  • Publication Date: Jun. 25, 2022
  • Vol. 20, Issue 10, 103901 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Electrically reconfigurable microwave metasurfaces [Invited]
Linda Shao, Jin Zhang, Ivan D. Rukhlenko, and Weiren Zhu
Metasurfaces are ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic responses. They have attracted tremendous attention owing to their ability to freely control the propagation of electromagnetic waves. With active elements incorporated into metasurface designs, one can realize tunable and reconfigurable metadevices with functionalities controlled by external stimuli, opening up a new platform to dynamically manipulate electromagnetic waves. In this article, we review the recent progress on tunable and reconfigurable metasurfaces, focusing on their operation principles and practical applications. We describe the approaches to the engineering of reconfigurable metasurfaces categorized into different classes based on the available active materials or elements, which can offer uniform manipulations of electromagnetic waves. We further summarize the recent achievements on programmable metasurfaces with constitutional meta-atoms locally tuned by external stimuli, which can dynamically control the wavefronts of electromagnetic waves. Finally, we discuss time-modulated metasurfaces, which are meaningful to exploit the temporal dimension by applying a dynamic switching of the coding sequence. The review is concluded by our outlook on possible future directions and existing challenges in this fast developing field.
Chinese Optics Letters
  • Publication Date: Sep. 15, 2022
  • Vol. 20, Issue 10, 103601 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Broadband angular momentum cascade via a multifocal graphene vortex generator
Zhongwei Jin, Guiyuan Cao, Hongtao Wang, Han Lin, Baohua Jia, and Cheng-Wei Qiu
Light beams carrying orbital angular momentum (OAM) have inspired various advanced applications, and such abundant practical applications in turn demand complex generation and manipulation of optical vortices. Here, we propose a multifocal graphene vortex generator, which can produce broadband angular momentum cascade containing continuous integer non-diffracting vortex modes. Our device naturally embodies a continuous spiral slit vortex generator and a zone plate, which enables the generation of high-quality continuous vortex modes with deep depths of foci. Meanwhile, the generated vortex modes can be simultaneously tuned through incident wavelength and position of the focal plane. The elegant structure of the device largely improves the design efficiency and can be fabricated by laser nanofabrication in a single step. Moreover, the outstanding property of graphene may enable new possibilities in enormous practical applications, even in some harsh environments, such as aerospace.
Chinese Optics Letters
  • Publication Date: Jul. 06, 2022
  • Vol. 20, Issue 10, 103602 (2022)
Ultrafast Optics: Fundamentals and Applications
Layer-dependent photoexcited carrier dynamics of WS2 observed using single pulse pump probe method
Lin Zhang, Jiamin Liu, Hao Jiang, Honggang Gu, and Shiyuan Liu
Understanding the ultrafast carrier dynamics and the mechanism of two-dimensional (2D) transition metal dichalcogenides (TMDs) is key to their applications in the field of optoelectronic devices. In this work, a single pulse pump probe method is introduced to detect the layer-dependent ultrafast carrier dynamics of monolayer and few-layer WS2 excited by a femtosecond pulse. Results show that the ultrafast carrier dynamics of the layered WS2 films can be divided into three stages: the fast photoexcitation phase with the characteristic time of 2–4 ps, the fast decay phase with the characteristic time of 4–20 ps, and the slow decay phase lasting several hundred picoseconds. Moreover, the layer dependency of the characteristic time of each stage has been observed, and the corresponding mechanism of free carrier dynamics has been discussed. It has been observed as well that the monolayer WS2 exhibits a unique rising time of carriers after photoexcitation. The proposed method can be expected to be an effective approach for studying the dynamics of the photoexcited carriers in 2D TMDs. Our results provide a comprehensive understanding of the photoexcited carrier dynamics of layered WS2, which is essential for its application in optoelectronics and photovoltaic devices.
Chinese Optics Letters
  • Publication Date: Aug. 03, 2022
  • Vol. 20, Issue 10, 100002 (2022)
Ultrafast Optics: Fundamentals and Applications
High spatial-resolution biological tissue imaging in the second near-infrared region via optical parametric amplification pumped by an ultrafast vortex pulse [Invited]
Xuanke Zeng, Congying Wang, Yi Cai, Qinggang Lin, Xiaowei Lu, Jiahe Lin, Xinming Yuan, Wenhua Cao, Yuexia Ai, and Shixiang Xu
Chinese Optics Letters
  • Publication Date: Aug. 28, 2022
  • Vol. 20, Issue 10, 100003 (2022)
Ultrafast Optics: Fundamentals and Applications
Background-free detection of molecular chirality using a single-color beam [Invited]
Yuhang Chen, Xiaosong Zhu, Pengfei Lan, and Peixiang Lu
Chinese Optics Letters
  • Publication Date: Sep. 09, 2022
  • Vol. 20, Issue 10, 100004 (2022)
Ultrafast Optics: Fundamentals and Applications
Rotational dephasing of the molecular alignment by centrifugal distortion [Invited]
Yunxia Huang, Guizhen Liu, and Shuwu Xu
The dephasing of molecular alignment can lead to the deformation of the alignment signal during its periodic revivals. Most studies are concentrated on the first few rotational revival periods of the molecular alignment and neglect the dephasing effect. However, study of the alignment dephasing is still of great significance for both the long-term dynamics of the molecular alignment and the dephasing itself. In this work, we theoretically demonstrate that the dephasing effect is correlated with both the rotational temperature and the rotational revival period of the molecules. The results present that the dephasing is especially significant for those molecules with long rotational revival period at high rotational temperatures. The physics behind it is explored by taking advantage of the coherence of the rotational quantum state population. This work deepens our understanding of rotational dynamics and rotational spectroscopy in molecular alignment.
Chinese Optics Letters
  • Publication Date: Aug. 30, 2022
  • Vol. 20, Issue 10, 100005 (2022)
Ultrafast Optics: Fundamentals and Applications
Laser control strategies in full-dimensional funneling dynamics: the case of pyrazine [Invited]
Samrit Mainali, Fabien Gatti, and Osman Atabek
Motivated by the major role funneling dynamics plays in light-harvesting processes, we built some laser control strategies inspired from basic mechanisms such as interference and kicks, and applied them to the case of pyrazine. We are studying the internal conversion between the two excited states, the highest and directly reachable from the initial ground state being considered as a donor and the lowest as an acceptor. The ultimate control objective is the maximum population deposit in the otherwise dark acceptor from a two-step process: radiative excitation of the donor, followed by a conical-intersection-mediated funneling towards the acceptor. The overall idea is to first obtain the control field parameters (individual pulses leading frequency and intensity, duration, and inter-pulse time delay) for tractable reduced dimensional models basically describing the conical intersection branching space. Once these parameters are optimized, they are fixed and used in full-dimensional dynamics describing the electronic population transfer. In the case of pyrazine, the reduced model is four-dimensional, whereas the full dynamics involves 24 vibrational modes. Within experimentally achievable electromagnetic field requirements, we obtain a robust control with about 60% of the ground state population deposited in the acceptor state, while about 16% remains in the donor. Moreover, we anticipate a possible transposition to the control of even larger molecular systems, for which only a small number of normal modes are active, among all the others acting as spectators in the dynamics.
Chinese Optics Letters
  • Publication Date: Sep. 22, 2022
  • Vol. 20, Issue 10, 100007 (2022)