Contents
2022
Volume: 20 Issue 6
13 Article(s)

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Research Articles
Fiber Optics and Optical Communications
Direct phase control method for binary phase-shift keying space coherent laser communication
Weijie Ren, Jianfeng Sun, Peipei Hou, Ronglei Han, Hongyu He, Haisheng Cong, Chaoyang Li, Longkun Zhang, and Yuxin Jiang
Chinese Optics Letters
  • Publication Date: Apr. 29, 2022
  • Vol. 20, Issue 6, 060601 (2022)
Single-wall carbon nanotube assisted all-optical wavelength conversion at 2.05 µm
Zonghui Tao, Wanzhuo Ma, Lei Du, Xin Li, Yan Lou, Tianshu Wang, and Huilin Jiang
We fully demonstrate the special requirements of a mid-infrared all-optical wavelength converter. The construction mechanism of a 2.05 µm all-optical wavelength converter based on the single-wall carbon nanotube (SWCNT) is proposed. Systematic experiments are carried out, and the converter device is successfully developed. With the assistance of SWCNT-coated microfiber, the conversion efficiency up to -45.57 dB is realized, and the tuning range can reach 9.72 nm. The experimental results verify the correctness of the proposed mechanism and the feasibility of the converter device so that it can be a new technical approach for all-optical wavelength conversion beyond 2 µm. We believe the research can extend the application of this composite waveguide in the field of all-optical communication.
Chinese Optics Letters
  • Publication Date: Apr. 29, 2022
  • Vol. 20, Issue 6, 060602 (2022)
Imaging Systems and Image Processing
Single-event-camera-based 3D trajectory measurement method for high-speed moving targets
Zeren Gao, Yong Su, and Qingchuan Zhang
High-speed target three-dimensional (3D) trajectory and velocity measurement methods have important uses in many fields, including explosive debris and rotating specimen trajectory tracking. The conventional approach uses a binocular system with two high-speed cameras to capture the target’s 3D motion information. Hardware cost for the conventional approach is high, and accurately triggering several high-speed cameras is difficult. Event-based cameras have recently received considerable attention due to advantages in dynamic range, temporal resolution, and power consumption. To address problems of camera synchronization difficulties, data redundancy, and motion blur in high-speed target 3D trajectory measurement, this Letter proposes a 3D trajectory measurement method based on a single-event camera and a four-mirror adaptor. The 3D trajectory and velocity of a particle flight process and a marker on a rotating disc were measured with the proposed method, and the results show that the proposed method can monitor the operational state of high-speed flying and rotating objects at a very low hardware cost.
Chinese Optics Letters
  • Publication Date: Apr. 26, 2022
  • Vol. 20, Issue 6, 061101 (2022)
Infrared and Terahertz Photonics
Revisiting the relationship between composite multiscale entropy and THz optical parameters with exterior product
Haishun Liu, Zhenwei Zhang, Meiyan Liang, and Cunlin Zhang
With the framework of exterior product, we investigate the relationship between composite multiscale entropy (CMSE) and refractive index and absorption coefficient by reanalyzing six concentrations of bovine serum albumin aqueous solutions from the published work. Two bivectors are constructed by CMSE and its square by the refractive index and absorption coefficient under vectorization. The desirable linear behaviors can be captured, not only between the defined two bivectors in normalized magnitudes, but also between the normalized magnitude of bivectors pertinent to CMSE and the magnitude of a single vector on the refractive index or absorption coefficient, with the processing of optimum selection. Besides that, the relationship between the coefficients of two bivectors is also considered. The results reveal that plenty of sound linear behaviors can be found and also suggest the scale of 15, 16 and frequency of 0.2, 0.21 THz are prominent for those linear behaviors. This work provides a new insight into the correlation between terahertz (THz) time and frequency domain information.
Chinese Optics Letters
  • Publication Date: May. 01, 2022
  • Vol. 20, Issue 6, 063701 (2022)
Integrated Optics
Reconfigurable nested photonic topological loops
Xiaoxue Li, Guanghao Rui, Yiping Cui, and Bing Gu
Photonic structures with topological edge states and resonance loops are both important in optical communication systems, but they are usually two separate structures. In order to obtain a photonic system combining properties from both, we design multiple-layer nested photonic topological structures. The nested topological loops not only have topological protection immune to structural disorder and defects, but also possess both the properties of unidirectional propagation and loop resonance. Through mode analysis and simulations, we find that the transport can form diverse circulation loops. Each loop has its own resonance frequencies and can be solely excited in the nested layered structure through choosing its resonance frequencies. As a result, this work shows great application prospects in the area of reconfigurable photonic circuits.
Chinese Optics Letters
  • Publication Date: May. 04, 2022
  • Vol. 20, Issue 6, 061301 (2022)
On-chip short-wave infrared multispectral detector based on integrated Fabry–Perot microcavities array | On the Cover
Zhiyi Xuan, Qingquan Liu, Zhuangzhuang Cui, Songlei Huang, Bo Yang, Chenlu Li, Shaowei Wang, and Wei Lu
Chinese Optics Letters
  • Publication Date: Apr. 27, 2022
  • Vol. 20, Issue 6, 061302 (2022)
Lasers, Optical Amplifiers, and Laser Optics
High efficiency of spectral beam combining by using large optical cavity lasers
Xiaoxu Xing, Xuyan Zhou, Hongwei Qu, Weiqiao Zhang, Lingqian Meng, Jing Liu, Yufei Wang, and Wanhua Zheng
Chinese Optics Letters
  • Publication Date: Apr. 27, 2022
  • Vol. 20, Issue 6, 061402 (2022)
Microwave Photonics
Photonic generation of switchable multi-format linearly chirped signals
Guodong Wang, Qingqing Meng, Hengli Han, Xuan Li, Yixiao Zhou, Zihang Zhu, Congrui Gao, He Li, and Shanghong Zhao
A compact and cost-effective photonic approach for generating switchable multi-format linearly chirped signals is proposed and experimentally demonstrated. The core component is a dual-drive Mach–Zehnder modulator driven by a coding sequence and a linearly chirped waveform. By properly setting the amplitudes of the coding sequence, a linearly chirped signal with different formats, including the frequency shift keying (FSK), phase shift keying (PSK), dual-band PSK, and FSK/PSK modulation formats, can be generated. Experiments are conducted to verify the feasibility of the proposed scheme. Linearly chirped signals with the above four formats are successfully generated. The scheme features multiple formats and high tunability based on a compact structure, which has potential applications in modern multifunctional systems.
Chinese Optics Letters
  • Publication Date: Apr. 29, 2022
  • Vol. 20, Issue 6, 063901 (2022)
Optical Materials
Temperature dependence of LiNbO3 dislocation density in the near-surface layer
Oksana Semenova, Aleksei Sosunov, Nikolai Prokhorov, and Roman Ponomarev
Density of dislocations in the near-surface layer was investigated in X-cut LiNbO3 depending on thermal annealing in the temperature range of 400°C–600°C. A dynamic model of randomly distributed dislocations has been developed for LiNbO3 by using X-ray diffraction. The experimental results showed that the dislocation density of the near-surface layer reached the minimum at the thermal annealing temperature of 500°C, with the analysis being performed when wet selective etching and X-ray diffraction methods were used. We concluded that homogenization annealing is an effective technique to improve the quality of photonic circuits based on LiNbO3. The results obtained are important for optical waveguides, LiNbO3-on-insulator-based micro-photonic devices, electro-optical modulators, sensors, etc.
Chinese Optics Letters
  • Publication Date: May. 04, 2022
  • Vol. 20, Issue 6, 061601 (2022)
Optoelectronics
Germanium-on-silicon avalanche photodiode for 1550 nm weak light signal detection at room temperature
Yuxuan Li, Xiaobin Liu, Xuetong Li, Lanxuan Zhang, Baisong Chen, Zihao Zhi, Xueyan Li, Guowei Zhang, Peng Ye, Guanzhong Huang, Deyong He, Wei Chen, Fengli Gao, Pengfei Guo, Xianshu Luo, Guoqiang Lo, and Junfeng Song
To optimize the dark current characteristic and detection efficiency of the 1550 nm weak light signal at room temperature, this work proposes a Ge-on-Si avalanche photodiode (APD) in Geiger mode, which could operate at 300 K. This lateral separate absorption charge multiplication APD shows a low breakdown voltage (Vbr) in Geiger mode of -7.42 V and low dark current of 0.096 nA at unity gain voltage (VGain=1 = -7.03 V). Combined with an RF amplifier module and counter, the detection system demonstrates a low dark count rate (DCR) of 1.1×106 counts per second and high detection efficiency η of 7.8% for 1550 nm weak coherent pulse detection at 300 K. The APD reported in this work weakens the dependence of the weak optical signal recognition on the low environment temperature and makes single-chip integration of the single-photon level detection system possible.
Chinese Optics Letters
  • Publication Date: Apr. 27, 2022
  • Vol. 20, Issue 6, 062501 (2022)
Quantum Optics and Quantum Information
Three methods for the single-photon transport in a chiral cavity quantum electrodynamics system
Jiang-Shan Tang, Lei Tang, and Keyu Xia
We investigate the single-photon transport problem in the system of a whispering-gallery mode microresonator chirally coupled with a two-level quantum emitter (QE). Conventionally, this chiral QE-microresonator coupling system can be studied by the master equation and the single-photon transport methods. Here, we provide a new approach, based on the transfer matrix, to assess the single-photon transmission of such a system. Furthermore, we prove that these three methods are equivalent. The corresponding relations of parameters among these approaches are precisely deduced. The transfer matrix can be extended to a multiple-resonator system interacting with two-level QEs in a chiral way. Therefore, our work may provide a convenient and intuitive form for exploring more complex chiral cavity quantum electrodynamics systems.
Chinese Optics Letters
  • Publication Date: Apr. 27, 2022
  • Vol. 20, Issue 6, 062701 (2022)
X-ray Optics
Perovskite-quantum-dots activated silica fiber X-ray dosimeter
Yuqing Xie, Yue Jing, Luyue Niu, Ci Wang, Lei Zhao, Jing Ren, and Jianzhong Zhang
A new type of X-ray fiber dosimeters is proposed that is based on the X-ray response of CsPbBr3 perovskite-quantum-dots (PQDs) activated silica fiber. Such a fiber sensor is constructed by covering a multimode silica fiber with PQDs embedded glass powders using a transparent high-temperature glue. Under X-ray irradiation, the fiber sensor emits bright green light at 525 nm, which can be readily recorded by a CCD spectrometer. The integrated radioluminescence intensity has an excellent linear response to the X-ray dose. Study is given to the fiber sensor concerning its thermal stability in a temperature range of room temperature up to 300°C, resistance to water erosion, and prolonged X-ray irradiation. The results verify that the proposed fiber sensor has the advantages of good thermal stability, chemical durability, and radiation hardness. The studied X-ray fiber sensor holds promise to be used in a real-time, in-situ, and remote radiation dose monitoring.
Chinese Optics Letters
  • Publication Date: Apr. 27, 2022
  • Vol. 20, Issue 6, 063401 (2022)

About the Cover

The short-wave infrared multispectral detection chip converts molecular information on the surface and inside of peach into readable data information. This is like Sun Wukong's piercing eyes, which can see the essence through appearance and accurately identify the material composition information that ordinary eyes cannot judge.