Volume: 20 Issue 2
20 Article(s)

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Research Articles
Atomic and Molecular Optics
Dark state atoms trapping in a magic-wavelength optical lattice near the nanofiber surface
Dianqiang Su, Xiateng Qin, Yuan Jiang, Kaidi Jin, Zhonghua Ji, Yanting Zhao, Liantuan Xiao, and Suotang Jia
We report the experimental realization of dark state atoms trapping in a nanofiber optical lattice. By applying the magic-wavelength trapping potentials of cesium atoms, the AC Stark shifts are strongly suppressed. The dark magneto-optical trap efficiently transfers the cold atoms from bright (6S1/2, F = 4) into dark state (6S1/2, F = 3) for hyperfine energy levels of cesium atoms. The observed transfer efficiency is as high as 98% via saturation measurement. The trapping lifetime of dark state atoms trapped by a nanofiber optical lattice is also investigated, which is the key element for realizing optical storage. This work contributes to the manipulation of atomic electric dipole spin waves and quantum information storage for fiber networks.
Chinese Optics Letters
  • Publication Date: Nov. 19, 2021
  • Vol.20 Issue, 2 020201 (2022)
Fiber Optics and Optical Communications
High-accuracy mode recognition method in orbital angular momentum optical communication system
Lin Zhao, Yuan Hao, Li Chen, Wenyi Liu, Meng Jin, Yi Wu, Jiamin Tao, Kaiqian Jie, and Hongzhan Liu
Vortex optical communication has been a hot research field in recent years. A key step is mode recognition in the orbital angular momentum (OAM) free-space optical (FSO) communication system. In this article, we propose an OAM mode recognition method based on image recognition technology, which uses the interferogram between the vortex beam and the Gaussian beam to identify the OAM mode. In order to resist the influence of atmospheric turbulence on the recognition accuracy, we added a Gaussian smoothing filter into the recognition process. Moreover, we used random phase screens to generate interferogram sets at distances of 1 km and 2 km. The verification result shows that the proposed scheme produces high identification accuracy for the distorted optical field. The average accuracy can reach 100% and 87.78% under the conditions of medium- and strong-turbulence levels, respectively. It is anticipated that these results might be helpful for improving the reliability of the OAM-FSO communication system in the future.
Chinese Optics Letters
  • Publication Date: Oct. 11, 2021
  • Vol.20 Issue, 2 020601 (2022)
Mode field switching in narrow linewidth mode-locked fiber laser
Shaokang Bai, Yaqiong Lu, and Zuxing Zhang
Acousto-optic interaction can be used for ultrafast optical field control in passively mode-locked fiber lasers. Here, we propose the use of an intracavity acousto-optic mode converter (AOMC) with combination of a few-mode fiber Bragg gratings (FM-FBG) to achieve narrow linewidth mode-locked pulse output with switchable transverse mode and wavelength in a ring fiber laser. Due to the selectivity of the FM-FBG to the input mode, the output mode and wavelength can be adjusted in the mode-locked fiber laser based on a semiconductor saturable absorption mirror. In experiments, by adjusting the acoustic frequency imposed in the AOMC, the wavelength of mode-locked pulses was switched from 1551.52 nm to 1550.21 nm, retaining the repetition rate of 12.68 MHz. At the same time, the mode conversion from the LP01 to the LP11 mode in the FM-FBG transmission port was achieved. This laser may find application in mode-division multiplexing systems.
Chinese Optics Letters
  • Publication Date: Dec. 03, 2021
  • Vol.20 Issue, 2 020602 (2022)
Instrumentation, Measurement, and Optical Sensing
High performance optical sensor based on double compound symmetric gratings
Chaoying Shi, Xiuhong Liu, Jinhua Hu, Haiyan Han, and Jijun Zhao
Chinese Optics Letters
  • Publication Date: Oct. 11, 2021
  • Vol.20 Issue, 2 021201 (2022)
Multi-channel pseudo-random coding single-photon ranging and imaging
Di Wu, Lei Yang, Xiuliang Chen, Zhaohui Li, and Guang Wu
We demonstrate a multi-channel pseudo-random coding single-photon ranging system. A pseudo-random multiplexing technique is proposed, which realizes multi-channel pseudo-random ranging only by using one single-photon detector and processing circuit. Compared with the time division multiplexing technique, it will not reduce the maximum unambiguous range while increasing the number of the ranging channel. Eight-channel pseudo-random coding single-photon ranging was realized with the ranging accuracy better than 2 cm. Moreover, photon counting imaging was realized through scanning the laser beams of the eight-channel pseudo-random ranging system. There is no crosstalk between channels, which is suitable for multi-beam long-distance single-photon Lidar.
Chinese Optics Letters
  • Publication Date: Nov. 19, 2021
  • Vol.20 Issue, 2 021202 (2022)
Integrated Optics
Terahertz out-of-plane coupler based on compact spot-size converter
Hongxiang Zhang, Changpei Liang, Jian Song, Chenzhong Fu, Xiaofei Zang, Lin Chen, and Jingya Xie
Low-loss dielectric terahertz (THz) chips are efficient platforms for diverse THz applications. One of the key elements in the chip is the coupler. Most of the available THz couplers are in-plane and couple the THz wave from the metal waveguide to the dielectric waveguide. However, out-of-plane couplers are more suitable for wafer-scale testing and tolerant of alignment variation. In this work, we propose an out-of-plane THz coupler for coupling the antenna to the dielectric waveguide. The device is constructed using a grating and a compact spot-size converter. As the conventional optical spot-size converters that apply directly to THz chips are too large, we have designed a compact spot-size converter based on a tapered waveguide with a lens. The total device is 2.9 cm long and can couple a 7 mm diameter THz beam to a 500 µm wide waveguide. The device can scan the THz beam, radiate the input rectangular waveguide mode to free space, and drive the rotation angle of the fan beam through the scanning frequency. We fabricated the device using a single lithography step on a silicon wafer. The out-of-plane coupling efficiency was found to be ∼5 dB at 194 GHz. The fan-beam steering range was found to be around 40° in the frequency range of 170–220 GHz. The proposed out-of-plane coupling technique may provide an effective way for THz wafer-scale testing with a higher degree of freedom for on-chip integration. Also, the proposed technique being non-mechanical, beam steering using it, may therefore find applications in THz radar, communication, and sensing.
Chinese Optics Letters
  • Publication Date: Oct. 11, 2021
  • Vol.20 Issue, 2 021301 (2022)
Lasers, Optical Amplifiers, and Laser Optics
Fabrication of side pump combiners when pumping with a laser diode and a fiber laser
Zhixian Li, Min Fu, Xiaofan Zhao, Hongye Li, Zilun Chen, Zefeng Wang, and Jinbao Chen
Chinese Optics Letters
  • Publication Date: Oct. 11, 2021
  • Vol.20 Issue, 2 021401 (2022)
High-power fiber laser with real-time mode switchability
Hanshuo Wu, Jiangtao Xu, Liangjin Huang, Xianglong Zeng, and Pu Zhou
Chinese Optics Letters
  • Publication Date: Nov. 17, 2021
  • Vol.20 Issue, 2 021402 (2022)
Development of single-resonant optical parametric oscillator with tunable output from 410 nm to 630 nm
Miao Wang, Jian Ma, Tingting Lu, Shanjiang Hu, Xiaolei Zhu, and Weibiao Chen
Chinese Optics Letters
  • Publication Date: Oct. 18, 2021
  • Vol.20 Issue, 2 021403 (2022)
Sidelobe suppression for coherent beam combining with laser beams placed along a Fermat spiral
Yang Gao, Jiali Liao, Jun Xu, and Zhanrong Zhou
Chinese Optics Letters
  • Publication Date: Nov. 17, 2021
  • Vol.20 Issue, 2 021405 (2022)
Design and fabrication of a compact, high-performance interference-filter-based external-cavity diode laser for use in the China Space Station
Lingqiang Meng, Pengyang Zhao, Fanchao Meng, Long Chen, Yong Xie, Yikun Wang, Wei Bian, Jianjun Jia, Tao Liu, Shougang Zhang, and Jianyu Wang
Chinese Optics Letters
  • Publication Date: Dec. 01, 2021
  • Vol.20 Issue, 2 021407 (2022)
Light-matter Interaction
Rapid fabrication of microrings with complex cross section using annular vortex beams
Chenchu Zhang, Hanchang Ye, Rui Cao, Shengyun Ji, Heng Zhang, Linhan Zhao, Sizhu Wu, and Hua Zhai
A ring-shaped focus, such as a focused vortex beam, has played an important role in microfabrication and optical tweezers. The shape and diameter of the ring-shaped focus can be easily adjusted by the topological charge of the vortex. However, the flow energy is also related to the topological charge, making the individual control of diameter and flow energy of the vortex beam impossible. Meanwhile, the shape of the focus of the vortex beam remains in the hollow ring. Expanding the shape of focus of structural light broadens the applications of the vortex beam in the field of microfabrication. Here, we proposed a ring-shaped focus with controllable gaps by multiplexing the vortex beam and annular beam. The multiplexed beam has several advantages, such as the diameter and flow energy of the focal point can be individually controlled and are not affected by the zero-order beam, and the gap size and position are controllable.
Chinese Optics Letters
  • Publication Date: Oct. 18, 2021
  • Vol.20 Issue, 2 023801 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Nanoparticle trapping by counter-surface plasmon polariton lens
Jingjing Hong, Xingping Zhou, Rui Zhuang, Wei Peng, Jiawei Liu, Aiping Liu, and Qin Wang
Chinese Optics Letters
  • Publication Date: Oct. 14, 2021
  • Vol.20 Issue, 2 023601 (2022)
Detection of cylindrical vector beams with chiral plasmonic lens
Chuangye Zhang, Changjun Min, Yuquan Zhang, Yanan Fu, Ling Li, Yulong Wang, and Xiaocong Yuan
Chinese Optics Letters
  • Publication Date: Nov. 19, 2021
  • Vol.20 Issue, 2 023602 (2022)
Nonlinear Optics
Optical limiting performances of transitional metal dichalcogenides MX2 (M = V, Nb, Ta; X = S, Se) with ultralow initial threshold and optical limiting threshold
Chenglu Liang, Enze Wang, Xian Li, Jing Wang, Yijun Liu, Binyi Chen, Hongxiang Chen, Yang Liu, and Xiangfang Peng
Chinese Optics Letters
  • Publication Date: Oct. 11, 2021
  • Vol.20 Issue, 2 021901 (2022)
Optical Design and Fabrication
Enhanced absorption and electrical modulation of graphene based on the parity-time symmetry optical structure
Lingjun Yi, and Changhong Li
In order to realize the ultrastrong absorption of graphene with electrical modulation properties, we designed a composite structure of graphene and parity-time (PT) symmetry photonic crystal, which is achieved by placing the graphene layer on the top layer of the PT symmetry photonic crystal. In this paper, the absorption properties of graphene and the electrical modulating properties of the structure were theoretically analyzed based on the transfer matrix method. The result shows that the proposed structure can achieve the absorption of 31.5 dB for the communication wavelength of 1550 nm; meanwhile, by setting the electric field intensity to ±0.02 V/nm, the absorption of graphene can be largely modulated to realize an electrically switchable effect, the modulation depth of graphene absorption can reach nearly 100%, and the operation speed is also close to 8.171 GHz. This investigation provides a novel approach to design graphene-based optoelectronic devices and optical communication devices.
Chinese Optics Letters
  • Publication Date: Dec. 01, 2021
  • Vol.20 Issue, 2 022201 (2022)
Optical Materials
High-color-purity, high-brightness and angle-insensitive red structural color
Jintong Liu, Kun Feng, Yusi Wang, Qingyuan Li, Nan Chen, and Yikun Bu
Chinese Optics Letters
  • Publication Date: Oct. 11, 2021
  • Vol.20 Issue, 2 021601 (2022)
Monolithic thin film lithium niobate electro-optic modulator with over 110 GHz bandwidth
Fan Yang, Xiansong Fang, Xinyu Chen, Lixin Zhu, Fan Zhang, Zhangyuan Chen, and Yanping Li
Chinese Optics Letters
  • Publication Date: Nov. 25, 2021
  • Vol.20 Issue, 2 022502 (2022)
Physical Optics
Depolarization index from Mueller matrix descatters imaging in turbid water
Fei Liu, Shichao Zhang, Pingli Han, Fangyi Chen, Lin Zhao, Yingying Fan, and Xiaopeng Shao
Chinese Optics Letters
  • Publication Date: Oct. 11, 2021
  • Vol.20 Issue, 2 022601 (2022)