Contents 1 Issue (s), 8 Article (s)

Vol. 21, Iss.12—Dec.1, 2023 • pp: 120002- Spec. pp:

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Research ArticlesVol. 21, Iss.12-Dec..1,2023
Fiber Optics and Optical Communications
Simultaneous determination of polarization states and mode coefficients of fiber LP modes with four-channel off-axis holography
Zhigang Han, Junbo Li, Siliang Liu, Fangxin Li, Zhenying Yang, Qi Wang, Jiuduo Rui, Hua Shen, and Rihong Zhu
Four-channel off-axis holography is proposed to simultaneously understand the polarization states and the mode coefficients of linearly polarized (LP) modes in few-mode fiber. Far-field off-axis holograms in the four polarization directions of the fiber laser were acquired at the same moment through a four-channel holographic device. The weights, the relative phase differences, and the polarization parameters of the vector fiber laser mode can be solved simultaneously. The simulated and experimental mode analysis of the laser output by 1060-XP fiber with 6 LP modes at 632.8 nm is conducted, which shows that the similarity of the total intensity distribution of the laser before and after mode analysis is above 0.97. The mode polarization states, the mode weights, and the relative phase differences of the few-mode laser can be determined simultaneously in a single shot by four-channel off-axis holography.
Chinese Optics Letters
  • Publication Date: Dec. 08, 2023
  • Vol. 21, Issue 12, 120601 (2023)
Imaging Systems and Image Processing
Light field information transmission through scattering media with high fidelity
Jianwei Ye, Tuqiang Pan, Kanpei Zheng, Zhichao Luo, Yi Xu, Songnian Fu, Yuncai Wang, and Yuwen Qin
Realizing high-fidelity optical information transmission through a scattering medium is of vital importance in both science and applications, such as short-range fiber communication and optical encryption. Theoretically, an input wavefront can be reconstructed by inverting the transmission matrix of the scattering medium. However, this deterministic method for retrieving light field information encoded in the wavefront has not yet been experimentally demonstrated. Herein, we demonstrate light field information transmission through different scattering media with near-unity fidelity. Multi-dimensional optical information can be delivered through either a multimode fiber or a ground glass without relying on any averaging or approximation, where their Pearson correlation coefficients can be up to 99%.
Chinese Optics Letters
  • Publication Date: Nov. 30, 2023
  • Vol. 21, Issue 12, 121101 (2023)
Nanophotonics, Metamaterials, and Plasmonics
Observation of topological rainbow in non-Hermitian systems | Fast Track
Cuicui Lu, Wen Zhao, Sheng Zhang, Yanji Zheng, Chenyang Wang, Yaohua Li, Yong-Chun Liu, Xiaoyong Hu, and Zhi Hong Hang
Topological photonic states have promising applications in slow light, photon sorting, and optical buffering. However, realizing such states in non-Hermitian systems has been challenging due to their complexity and elusive properties. In this work, we have experimentally realized a topological rainbow in non-Hermitian photonic crystals by controlling loss in the microwave frequency range for what we believe is the first time. We reveal that the lossy photonic crystal provides a reliable platform for the study of non-Hermitian photonics, and loss is also taken as a degree of freedom to modulate topological states, both theoretically and experimentally. This work opens a way for the construction of a non-Hermitian photonic crystal platform, will greatly promote the development of topological photonic devices, and will lay a foundation for the real-world applications.
Chinese Optics Letters
  • Publication Date: Nov. 03, 2023
  • Vol. 21, Issue 12, 123601 (2023)
Nonlinear Optics
Experimental demonstration of TE/TM polarization-independent frequency upconversion assisted by polarization coupling
Tingting Ding, Yongzhi Tang, Xuerui Sun, Yiwen Huang, Bei Jiang, Jin Liu, Zhiwei Li, Yuanlin Zheng, and Xianfeng Chen
Optical frequency conversion based on the second-order nonlinearity (χ(2)) only occurs in anisotropic media (or at interfaces) and thus is intrinsically polarization-dependent. But for practical applications, polarization-insensitive or independent operation is highly sought after. Here, by leveraging polarization coupling and second-order nonlinearity, we experimentally demonstrate a paradigm of TE/TM polarization-independent frequency upconversion, i.e., sum frequency generation, in the periodically poled lithium niobate-on-insulator ridge waveguide. The cascading of quasi-phase-matched polarization coupling and nonlinear frequency conversion is exploited. With a proper transverse electric field, TE and TM mode fundamental waves can be frequency-upconverted with an equal efficiency in the frequency converter. The proposed method may find ready application in all-optical wavelength conversion and upconversion detection technologies.
Chinese Optics Letters
  • Publication Date: Nov. 20, 2023
  • Vol. 21, Issue 12, 121901 (2023)
Optical Design and Fabrication
Multi-direction bending sensing based on spot pattern demodulation of dual-hole fiber
Boyao Li, Yaoyao Liang, Zhongye Xie, Xiaojie Zuo, and Jinghua Sun
A multi-direction bending sensor based on spot pattern demodulation of a dual-hole fiber (DHF) is proposed. By using the interference and scattering in a DHF, the related multidirectional variations can be captured by the optical field. Furthermore, the multi-directional bending characteristics of the fiber are quantitatively described by the pattern of the output light spot, achieving multidirectional bending sensing. In addition, considering the subtle changes in the deformation patterns over time, a convolutional neural network (CNN) model based on deep learning is introduced for accurate recognition and prediction of the bending angle. The experimental results show that the sensor can perceive different bending angles in four directions. These outstanding results indicate that the multi-directional bending sensor based on dual-hole interference pattern decoding has potential applications in multi-directional quantitative sensing and artificial intelligence perception.
Chinese Optics Letters
  • Publication Date: Dec. 06, 2023
  • Vol. 21, Issue 12, 122201 (2023)
Optical Materials
Speckle-based interrogation system for quasi-distributed weak fiber Bragg gratings
Jinchao Tao, Qin Liang, Yue Li, Yanlong Meng, Yanqing Qiu, Pengwei Zhou, Chunliu Zhao, Juan Kang, Xianchao Zhang, Zhiguo Jiang, Le Wang, and Yi Li
A simple quasi-distributed fiber sensing interrogation system based on random speckles is proposed for weak fiber Bragg gratings (WFBGs) in this work. Without using tunable lasers or spectrometers, a piece of multimode fiber is applied to interrogate the WFBGs relying on the wavelength sensitivity of speckles. Instead of the CCD sensor, an InGaAs quadrant detector serves as the receiver to capture the fast-changing speckle patterns. A supervised deep learning algorithm of the multilayer perceptron architecture is implemented to process speckle data and to interrogate temperature changes or dynamic strains. The proposed demodulation system is experimentally demonstrated for WFBGs with 0.1% reflectivity. The experimental results demonstrate that the new system is capable of measuring temperature change with an accuracy of 1°C and achieving dynamic frequency of 100 Hz. This speckle-based interrogation system paves a new way for distributed WFBGs sensing with a simple design.
Chinese Optics Letters
  • Publication Date: Dec. 08, 2023
  • Vol. 21, Issue 12, 121601 (2023)
Special Issue on The 20Th Anniversary of Wuhan National Laboratory for Optoelectronics (WNLO)
Measurement of molecular alignment with deep learning-based M-XFROG technique [Invited]
Wanchen Tao, Siqi Sun, Lixin He, Yanqing He, Jianchang Hu, Yu Deng, Chengqing Xu, Pengfei Lan, and Peixiang Lu
Chinese Optics Letters
  • Publication Date: Oct. 03, 2023
  • Vol. 21, Issue 12, 120021 (2023)