Journals >Chinese Optics Letters
Contents
3 Issue (s), 33 Article (s)
Vol.20, Iss.7—Jul.1, 2022 • pp: 071101- Spec. pp:
Vol.20, Iss.6—Jun.1, 2022 • pp: 060601- Spec. pp:
Vol.20, Iss.5—May.1, 2022 • pp: 050502- Spec. pp:
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Research ArticlesVol.20, Iss.7-Jul..1,2022
Imaging Systems and Image Processing
In-situ laser-induced surface damage inspection based on image super-resolution and adaptive segmentation methodFengdong Chen, Jingyang Sun, Qian Wang, Hongbo Zhu, Fa Zeng, Yueyue Han, Cheng Lu, and Guodong Liu
In-situ laser-induced surface damage inspection plays a key role in protecting the large aperture optics in an inertial confinement fusion (ICF) high-power laser facility. In order to improve the initial damage detection capabilities, an in-situ inspection method based on image super-resolution and adaptive segmentation method is presented. Through transfer learning and integration of various attention mechanisms, the super-resolution reconstruction of darkfield images with less texture information is effectively realized, and, on the basis of image super-resolution, an adaptive image segmentation method is designed, which effectively adapts to the damage detection problems under conditions of uneven illumination and weak signal. An online experiment was carried out by using edge illumination and the telescope optical imaging system, and the validity of the method was proved by the experimental results.In-situ laser-induced surface damage inspection plays a key role in protecting the large aperture optics in an inertial confinement fusion (ICF) high-power laser facility. In order to improve the initial damage detection capabilities, an in-situ inspection method based on image super-resolution and adaptive segmentation method is presented. Through transfer learning and integration of various attention mechanisms, the super-resolution reconstruction of darkfield images with less texture information is effectively realized, and, on the basis of image super-resolution, an adaptive image segmentation method is designed, which effectively adapts to the damage detection problems under conditions of uneven illumination and weak signal. An online experiment was carried out by using edge illumination and the telescope optical imaging system, and the validity of the method was proved by the experimental results.
Chinese Optics Letters
- Publication Date: Jul. 10, 2022
- Vol.20 Issue, 7 071101 (2022)
Integrated Optics
LiNbO3 channel and ridge waveguides based on helium ion implantation combined with lithography and precise diamond dicingSumei Wang, Jinhua Zhao, Jinjun Gu, Mingyang Bu, Li Fan, Shuang Li, Xifeng Qin, Yicun Yao, Yingying Ren, and Lei Wang
Lithium niobate (
Chinese Optics Letters
- Publication Date: Jul. 10, 2022
- Vol.20 Issue, 7 071301 (2022)
Lasers, Optical Amplifiers, and Laser Optics
Low-threshold continuous operation of fiber gas Raman laser based on large-core anti-resonant hollow-core fiberXinyue Zhu, Fei Yu, Dakun Wu, Yan Feng, Shufen Chen, Yi Jiang, and Lili Hu
Continuous operation of fiber gas Raman lasing at the 1135 nm wavelength is experimentally demonstrated with an output power exceeding 26 W. Rotational stimulated Raman scattering (Rot-SRS) is generated in the hydrogen gas filled 50 m homemade anti-resonant hollow-core fiber (AR-HCF). A single-frequency fiber laser at the 1064 nm wavelength is used as the pump source, and a minimum threshold of 31.5 W is measured where the core diameter of AR-HCF reaches 37 µm. Up to 40.4% power conversion efficiency of forward Rot-SRS is achieved in the single-pass configuration, corresponding to a quantum efficiency of 43.1%. Over 1 W strong backward Rot-SRS is observed in the experiment, ultimately limiting the further increase of Rot-SRS generation in the forward direction.Continuous operation of fiber gas Raman lasing at the 1135 nm wavelength is experimentally demonstrated with an output power exceeding 26 W. Rotational stimulated Raman scattering (Rot-SRS) is generated in the hydrogen gas filled 50 m homemade anti-resonant hollow-core fiber (AR-HCF). A single-frequency fiber laser at the 1064 nm wavelength is used as the pump source, and a minimum threshold of 31.5 W is measured where the core diameter of AR-HCF reaches 37 µm. Up to 40.4% power conversion efficiency of forward Rot-SRS is achieved in the single-pass configuration, corresponding to a quantum efficiency of 43.1%. Over 1 W strong backward Rot-SRS is observed in the experiment, ultimately limiting the further increase of Rot-SRS generation in the forward direction.
Chinese Optics Letters
- Publication Date: Jul. 10, 2022
- Vol.20 Issue, 7 071401 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Inverse design of 1D color splitter for high-efficiency color imagingJiahao Li, Mengwei Cao, Weili Liang, Yilin Zhang, Zhenwei Xie, and Xiaocong Yuan
We introduce a simple one-dimensional (1D) structure in the design of 1D color splitters (1D-CSs) with RGB unit cells for color imaging and propose a single-to-double-layer design in 1D-CSs. Based on inverse design metasurfaces, we demonstrate numerically a single-layer 1D-CS with a full-color efficiency of 46.2% and a double-layer 1D-CS with a full-color efficiency of 48.2%; both of them are significantly higher than that of traditional color filters. Moreover, we demonstrate a 1D-CS that has application value by evaluating the double-layer 1D-CS’s performances in terms of incident angle sensitivity, polarization angle sensitivity, and assembly tolerance.We introduce a simple one-dimensional (1D) structure in the design of 1D color splitters (1D-CSs) with RGB unit cells for color imaging and propose a single-to-double-layer design in 1D-CSs. Based on inverse design metasurfaces, we demonstrate numerically a single-layer 1D-CS with a full-color efficiency of 46.2% and a double-layer 1D-CS with a full-color efficiency of 48.2%; both of them are significantly higher than that of traditional color filters. Moreover, we demonstrate a 1D-CS that has application value by evaluating the double-layer 1D-CS’s performances in terms of incident angle sensitivity, polarization angle sensitivity, and assembly tolerance.
Chinese Optics Letters
- Publication Date: Jul. 10, 2022
- Vol.20 Issue, 7 073601 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Probing fluorescence quantum efficiency of single molecules in an organic matrix by monitoring lifetime change during sublimationPenglong Ren, Shangming Wei, Pu Zhang, and Xue-Wen Chen
Quantum efficiency is a critical piece of information of a quantum emitter and regulates the emitter’s fluorescence decay dynamics in an optical environment through the Purcell effect. Here, we present a simple way to experimentally probe fluorescence quantum efficiency of single dibenzoterrylene molecules embedded in a thin anthracene microcrystal obtained through a co-sublimation process. In particular, we correlate the fluorescence lifetime change of single dibenzoterrylene molecules with the variation of the matrix thickness due to natural sublimation. With the identification of the molecule emission dipole orientation, we could deduce the near-unity intrinsic quantum efficiency of dibenzoterrylene molecules in the anthracene matrix.Quantum efficiency is a critical piece of information of a quantum emitter and regulates the emitter’s fluorescence decay dynamics in an optical environment through the Purcell effect. Here, we present a simple way to experimentally probe fluorescence quantum efficiency of single dibenzoterrylene molecules embedded in a thin anthracene microcrystal obtained through a co-sublimation process. In particular, we correlate the fluorescence lifetime change of single dibenzoterrylene molecules with the variation of the matrix thickness due to natural sublimation. With the identification of the molecule emission dipole orientation, we could deduce the near-unity intrinsic quantum efficiency of dibenzoterrylene molecules in the anthracene matrix.
Chinese Optics Letters
- Publication Date: Jul. 10, 2022
- Vol.20 Issue, 7 073602 (2022)
Physical Optics
Underwater Bessel-like beams with enlarged depth of focus based on fiber microaxiconXiaoying He, Mengyuan Li, and Lan Rao
Underwater optical wireless communication, which is useful for oceanography, environmental monitoring, and underwater surveillance, suffers the limit of the absorption attenuation and Mie–Rayleigh scattering of the lights. Here, Bessel-like beams generated by a fiber microaxicon is utilized for underwater wireless propagation. Underwater, the cone angle for generating Bessel-like beams starts from 46°, which is smaller than that in air for Bessel-like beams. When the cone angle of the fiber microaxicons is about 140°, the depth of focus underwater, which is four times as long as the depth of focus in air, has enlarged about 28 µm, 36.12 µm, and 50.7 µm for 470 nm, 520 nm, and 632 nm visible lights. The transmission distance of the Bessel beams for visible lights has been simulated by using Henyey–Greenstein–Rayleigh phase function methods and spectral absorption by bio-optical model due to Monte Carlo methods. The results show that the propagation distance could reach 4000 m, which overcome the limit of the Mie–Rayleigh scattering and absorption attenuation underwater.Underwater optical wireless communication, which is useful for oceanography, environmental monitoring, and underwater surveillance, suffers the limit of the absorption attenuation and Mie–Rayleigh scattering of the lights. Here, Bessel-like beams generated by a fiber microaxicon is utilized for underwater wireless propagation. Underwater, the cone angle for generating Bessel-like beams starts from 46°, which is smaller than that in air for Bessel-like beams. When the cone angle of the fiber microaxicons is about 140°, the depth of focus underwater, which is four times as long as the depth of focus in air, has enlarged about 28 µm, 36.12 µm, and 50.7 µm for 470 nm, 520 nm, and 632 nm visible lights. The transmission distance of the Bessel beams for visible lights has been simulated by using Henyey–Greenstein–Rayleigh phase function methods and spectral absorption by bio-optical model due to Monte Carlo methods. The results show that the propagation distance could reach 4000 m, which overcome the limit of the Mie–Rayleigh scattering and absorption attenuation underwater.
Chinese Optics Letters
- Publication Date: Jul. 10, 2022
- Vol.20 Issue, 7 072601 (2022)
Spectroscopy
Optical analysis method for fast plasma characterization of high-speed miniaturized synthetic jetYe Yuan, Yan Zhang, Cheng Guo, Xiaolu Kang, Zhong Yan, Xiaoping Huang, and Qing Zhao
In this paper, a new optical analysis method for plasma characterization is proposed. Plasma characteristics are obtained directly by measuring the plasma luminous color, rather than the complex spectral diagnosis method, which is difficult to obtain at high speed. By using the light transmittance curve of the human cornea, the RGB coordinates are calculated from the measured plasma spectrum data. Plasma characteristics are diagnosed using the Boltzmann plot method and the Stark broadening method. The corresponding relationship of the electron temperature, electron density data points, and luminous color is established and analyzed. Our research results indicate that this optical analysis method is feasible and promising for fast plasma characterization.In this paper, a new optical analysis method for plasma characterization is proposed. Plasma characteristics are obtained directly by measuring the plasma luminous color, rather than the complex spectral diagnosis method, which is difficult to obtain at high speed. By using the light transmittance curve of the human cornea, the RGB coordinates are calculated from the measured plasma spectrum data. Plasma characteristics are diagnosed using the Boltzmann plot method and the Stark broadening method. The corresponding relationship of the electron temperature, electron density data points, and luminous color is established and analyzed. Our research results indicate that this optical analysis method is feasible and promising for fast plasma characterization.
Chinese Optics Letters
- Publication Date: Jul. 10, 2022
- Vol.20 Issue, 7 073001 (2022)
Research ArticlesVol.20, Iss.6-Jun..1,2022
Fiber Optics and Optical Communications
Direct phase control method for binary phase-shift keying space coherent laser communicationWeijie Ren, Jianfeng Sun, Peipei Hou, Ronglei Han, Hongyu He, Haisheng Cong, Chaoyang Li, Longkun Zhang, and Yuxin Jiang
An optical phase locking method based on direct phase control is proposed. The core of this method is to synchronize the carrier by directly changing the phase of the local beam. The corresponding experimental device and the supporting algorithm were configured to verify the feasibility of this method. Phase locking can be completed without cycle skipping, and the acquisition time is 530 ns. Without an optical preamplifier, a sensitivity of
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 060601 (2022)
Fiber Optics and Optical Communications
Single-wall carbon nanotube assisted all-optical wavelength conversion at 2.05 µmZonghui 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
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 060602 (2022)
Imaging Systems and Image Processing
Single-event-camera-based 3D trajectory measurement method for high-speed moving targetsZeren 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.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: Jun. 10, 2022
- Vol.20 Issue, 6 061101 (2022)
Infrared and Terahertz Photonics
Revisiting the relationship between composite multiscale entropy and THz optical parameters with exterior productHaishun 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.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: Jun. 10, 2022
- Vol.20 Issue, 6 063701 (2022)
Integrated Optics
Reconfigurable nested photonic topological loopsXiaoxue 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.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: Jun. 10, 2022
- Vol.20 Issue, 6 061301 (2022)
Integrated Optics
On-chip short-wave infrared multispectral detector based on integrated Fabry–Perot microcavities arrayOn the CoverZhiyi Xuan, Qingquan Liu, Zhuangzhuang Cui, Songlei Huang, Bo Yang, Chenlu Li, Shaowei Wang, and Wei Lu
We demonstrate an ultra-compact short-wave infrared (SWIR) multispectral detector chip by monolithically integrating the narrowband Fabry–Perot microcavities array with the InGaAs detector focal plane array. A 16-channel SWIR multispectral detector has been fabricated for demonstration. Sixteen different narrowband response spectra are acquired on a
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 061302 (2022)
Lasers, Optical Amplifiers, and Laser Optics
1.65 µm square-FP coupled cavity semiconductor laser for methane gas detectionEditors' PickYingrun Fan, Jinlong Xiao, Zhengzheng Shen, Youzeng Hao, Jiachen Liu, Ke Yang, Yuede Yang, and Yongzhen Huang
We report a 1.65 µm square-Fabry–Pérot (FP) coupled cavity semiconductor laser for methane gas detection. The laser output optical power can reach 7.4 mW with the side mode suppression ratio about 40 dB. The wavelength tuning range is 2 nm by adjusting the FP cavity injection current, covering the methane absorption line at 1653.72 nm. The lasing wavelength can also be tuned by adjusting the square microcavity injection current or temperature, respectively. Methane gas detection is successfully demonstrated utilizing this laser.We report a 1.65 µm square-Fabry–Pérot (FP) coupled cavity semiconductor laser for methane gas detection. The laser output optical power can reach 7.4 mW with the side mode suppression ratio about 40 dB. The wavelength tuning range is 2 nm by adjusting the FP cavity injection current, covering the methane absorption line at 1653.72 nm. The lasing wavelength can also be tuned by adjusting the square microcavity injection current or temperature, respectively. Methane gas detection is successfully demonstrated utilizing this laser.
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 061401 (2022)
Lasers, Optical Amplifiers, and Laser Optics
High efficiency of spectral beam combining by using large optical cavity lasersXiaoxu Xing, Xuyan Zhou, Hongwei Qu, Weiqiao Zhang, Lingqian Meng, Jing Liu, Yufei Wang, and Wanhua Zheng
We studied the spectral beam combining (SBC) of a large optical cavity (LOC) laser array to achieve high-power and high-brightness laser output. We discussed the characteristics of the external cavity feedback efficiency and the focal length of the transform lens for lasers with different waveguide thicknesses. We have found that using LOC laser diodes can increase the proportion of external cavity feedback, thereby improving the SBC efficiency. At a current of 90 A, the CW output power of the SBC system is 59.2 W, and the SBC efficiency reaches up to 102.8%. All emitters of the laser array have achieved spectral locking with a spectral width of 11.67 nm, and the beam parameter product is 4.38 mm·mrad.We studied the spectral beam combining (SBC) of a large optical cavity (LOC) laser array to achieve high-power and high-brightness laser output. We discussed the characteristics of the external cavity feedback efficiency and the focal length of the transform lens for lasers with different waveguide thicknesses. We have found that using LOC laser diodes can increase the proportion of external cavity feedback, thereby improving the SBC efficiency. At a current of 90 A, the CW output power of the SBC system is 59.2 W, and the SBC efficiency reaches up to 102.8%. All emitters of the laser array have achieved spectral locking with a spectral width of 11.67 nm, and the beam parameter product is 4.38 mm·mrad.
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 061402 (2022)
Lasers, Optical Amplifiers, and Laser Optics
High efficiency of spectral beam combining by using large optical cavity lasersXiaoxu Xing, Xuyan Zhou, Hongwei Qu, Weiqiao Zhang, Lingqian Meng, Jing Liu, Yufei Wang, and Wanhua Zheng
We studied the spectral beam combining (SBC) of a large optical cavity (LOC) laser array to achieve high-power and high-brightness laser output. We discussed the characteristics of the external cavity feedback efficiency and the focal length of the transform lens for lasers with different waveguide thicknesses. We have found that using LOC laser diodes can increase the proportion of external cavity feedback, thereby improving the SBC efficiency. At a current of 90 A, the CW output power of the SBC system is 59.2 W, and the SBC efficiency reaches up to 102.8%. All emitters of the laser array have achieved spectral locking with a spectral width of 11.67 nm, and the beam parameter product is 4.38 mm·mrad.We studied the spectral beam combining (SBC) of a large optical cavity (LOC) laser array to achieve high-power and high-brightness laser output. We discussed the characteristics of the external cavity feedback efficiency and the focal length of the transform lens for lasers with different waveguide thicknesses. We have found that using LOC laser diodes can increase the proportion of external cavity feedback, thereby improving the SBC efficiency. At a current of 90 A, the CW output power of the SBC system is 59.2 W, and the SBC efficiency reaches up to 102.8%. All emitters of the laser array have achieved spectral locking with a spectral width of 11.67 nm, and the beam parameter product is 4.38 mm·mrad.
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 062702 (2022)
Microwave Photonics
Photonic generation of switchable multi-format linearly chirped signalsGuodong 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.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: Jun. 10, 2022
- Vol.20 Issue, 6 063901 (2022)
Optical Materials
Temperature dependence of LiNbO3 dislocation density in the near-surface layerOksana Semenova, Aleksei Sosunov, Nikolai Prokhorov, and Roman Ponomarev
Density of dislocations in the near-surface layer was investigated in X-cut
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 061601 (2022)
Optoelectronics
Germanium-on-silicon avalanche photodiode for 1550 nm weak light signal detection at room temperatureYuxuan 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
Chinese Optics Letters
- Publication Date: Jun. 10, 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 systemJiang-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.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: Jun. 10, 2022
- Vol.20 Issue, 6 062701 (2022)
X-Ray Optics
Perovskite-quantum-dots activated silica fiber X-ray dosimeterYuqing 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
Chinese Optics Letters
- Publication Date: Jun. 10, 2022
- Vol.20 Issue, 6 063401 (2022)
Research ArticlesVol.20, Iss.5-May..1,2022
Diffraction, Gratings, and Holography
Machine-learning-based high-speed lensless large-field holographic projection using double-sampling Fresnel diffraction methodChentianfei Shen, Tong Shen, Qi Chen, Qinghan Zhang, and Jihong Zheng
Machine learning can effectively accelerate the runtime of a computer-generated hologram. However, the angular spectrum method and single fast Fresnel transform-based machine learning acceleration algorithms are still limited in the field-of-view angle of projection. In this paper, we propose an efficient method for the fast generation of large field-of-view holograms combining stochastic gradient descent (SGD), neural networks, and double-sampling Fresnel diffraction (DSFD). Compared with the traditional Gerchberg–Saxton (GS) algorithm, the DSFD-SGD algorithm has better reconstruction quality. Our neural network can be automatically trained in an unsupervised manner with a training set of target images without labels, and its combination with the DSFD can improve the optimization speed significantly. The proposed DSFD-Net method can generate 2000-resolution holograms in 0.05 s. The feasibility of the proposed method is demonstrated with simulations and experiments.Machine learning can effectively accelerate the runtime of a computer-generated hologram. However, the angular spectrum method and single fast Fresnel transform-based machine learning acceleration algorithms are still limited in the field-of-view angle of projection. In this paper, we propose an efficient method for the fast generation of large field-of-view holograms combining stochastic gradient descent (SGD), neural networks, and double-sampling Fresnel diffraction (DSFD). Compared with the traditional Gerchberg–Saxton (GS) algorithm, the DSFD-SGD algorithm has better reconstruction quality. Our neural network can be automatically trained in an unsupervised manner with a training set of target images without labels, and its combination with the DSFD can improve the optimization speed significantly. The proposed DSFD-Net method can generate 2000-resolution holograms in 0.05 s. The feasibility of the proposed method is demonstrated with simulations and experiments.
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 050502 (2022)
Fiber Optics and Optical Communications
Real-time reception of NHS-OFDM signal with SPA-enhanced channel estimation for intensity-modulated direct-detection systemsGang Chen, Ming Chen, Wen Chen, Lede Yin, Aitao Deng, Yuxin Cai, and Dengqiao Wang
In this Letter, we have experimentally verified a low-complexity subcarrier pairwise-averaging (SPA)-enhanced channel estimation (CE) method for small-size fast Fourier transform (FFT) non-Hermitian symmetric orthogonal frequency-division multiplexing (NHS-OFDM) transceivers. Compared with intra-symbol frequency averaging (ISFA), more than 20% look-up tables and 10% logic power consumption can be saved. The least-square (LS), ISFA, and SPA CE methods are compared by offline and real-time digital signal processing approaches. The results show that the receiver sensitivity of the SPA NHS-OFDM transmission system with 64/128-point FFT can be improved by more than 1 dB at the bit error rate of 3.8 × 10-3 compared to the LS.In this Letter, we have experimentally verified a low-complexity subcarrier pairwise-averaging (SPA)-enhanced channel estimation (CE) method for small-size fast Fourier transform (FFT) non-Hermitian symmetric orthogonal frequency-division multiplexing (NHS-OFDM) transceivers. Compared with intra-symbol frequency averaging (ISFA), more than 20% look-up tables and 10% logic power consumption can be saved. The least-square (LS), ISFA, and SPA CE methods are compared by offline and real-time digital signal processing approaches. The results show that the receiver sensitivity of the SPA NHS-OFDM transmission system with 64/128-point FFT can be improved by more than 1 dB at the bit error rate of 3.8 × 10-3 compared to the LS.
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 050601 (2022)
Lasers, Optical Amplifiers, and Laser Optics
Generation of tail-free short pulses using high-pressure CO2 laserYue Lu, Ziren Zhu, Jinzhou Bai, Xinjun Su, Rongqing Tan, Jinghan Ye, and Yijun Zheng
The spectral linewidth of a transversely excited pulsed
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 051401 (2022)
Lasers, Optical Amplifiers, and Laser Optics
High signal-to-noise ratio fiber laser at 1596 nm based on a Bi/Er/La co-doped silica fiberLei Yang, Jianxiang Wen, Yan Wu, Ying Wan, Longzhao Zeng, Wei Chen, Fufei Pang, Xiaobei Zhang, and Tingyun Wang
We fabricate a high-performance Bi/Er/La co-doped silica fiber with a fluorescence intensity of
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 051402 (2022)
Light-Matter Interaction
Trapping and revolving micron particles by transformable line traps of optical tweezersLingyao Yu, Yuan Jia, Xujin Hu, Shaofei Wang, Hongyu Chen, Shuai Liu, Hongchang Deng, Maowen Wang, and Jun Yin
Optical line tweezers have been an efficient tool for the manipulation of large micron particles. In this paper, we propose to create line traps with transformable configurations by using the transverse electromagnetic mode-like laser source. We designed an optical path to simulate the generation of the astigmatic beams and line traps with a series of lenses to realize the rotational transformation with respect to the rotation angle of cylindrical lenses. It is shown that the spherical particles with diameters ranging from 5 μm to 20 μm could be trapped, aligned, and revolved in experiment. The periodical trapping forces generated by transformable line traps might open an alternative way to investigate the mechanical properties of soft particles and biological cells.Optical line tweezers have been an efficient tool for the manipulation of large micron particles. In this paper, we propose to create line traps with transformable configurations by using the transverse electromagnetic mode-like laser source. We designed an optical path to simulate the generation of the astigmatic beams and line traps with a series of lenses to realize the rotational transformation with respect to the rotation angle of cylindrical lenses. It is shown that the spherical particles with diameters ranging from 5 μm to 20 μm could be trapped, aligned, and revolved in experiment. The periodical trapping forces generated by transformable line traps might open an alternative way to investigate the mechanical properties of soft particles and biological cells.
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 053801 (2022)
Microwave Photonics
Unidirectional electromagnetic windmill scattering in a magnetized gyromagnetic cylinderJianfeng Chen, Jianbo Pan, Yidong Zheng, Wenyao Liang, and Zhi-Yuan Li
We present a discovery of an unusual unidirectionally rotating windmill scattering of electromagnetic waves by a magnetized gyromagnetic cylinder via an analytical theory for rigorous solution to fields and charges and an understanding of the underlying mathematical and physical mechanisms. Mathematically, the generation of nonzero off-diagonal components can break the symmetry of forward and backward scattering coefficients, producing unidirectional windmill scattering. Physically, this windmill scattering originates from the nonreciprocal unidirectional rotation of polarized magnetic charges on the surface of a magnetized gyromagnetic cylinder, which drives the scattering field to radiate outward in the radial direction and unidirectionally emit in the tangential direction. Interestingly, the unidirectional electromagnetic windmill scattering is insensitive to the excitation direction. Moreover, we also discuss the size dependence of unidirectional windmill scattering by calculating the scattering spectra of the gyromagnetic cylinder. These results are helpful for exploring and understanding novel interactions between electromagnetic waves and gyromagnetic materials or structures and offer deep insights for comprehending topological photonic states in gyromagnetic systems from the aspect of fundamental classical electrodynamics and electromagnetics.We present a discovery of an unusual unidirectionally rotating windmill scattering of electromagnetic waves by a magnetized gyromagnetic cylinder via an analytical theory for rigorous solution to fields and charges and an understanding of the underlying mathematical and physical mechanisms. Mathematically, the generation of nonzero off-diagonal components can break the symmetry of forward and backward scattering coefficients, producing unidirectional windmill scattering. Physically, this windmill scattering originates from the nonreciprocal unidirectional rotation of polarized magnetic charges on the surface of a magnetized gyromagnetic cylinder, which drives the scattering field to radiate outward in the radial direction and unidirectionally emit in the tangential direction. Interestingly, the unidirectional electromagnetic windmill scattering is insensitive to the excitation direction. Moreover, we also discuss the size dependence of unidirectional windmill scattering by calculating the scattering spectra of the gyromagnetic cylinder. These results are helpful for exploring and understanding novel interactions between electromagnetic waves and gyromagnetic materials or structures and offer deep insights for comprehending topological photonic states in gyromagnetic systems from the aspect of fundamental classical electrodynamics and electromagnetics.
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 053901 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Optical fiber hydrogen sensor using metasurfaces composed of palladiumShunshuo Cai, Wanhan Hu, Yiman Liu, Juan Ning, Sixuan Feng, Chao Jin, Lingling Huang, and Xin Li
Palladium-based hydrogen sensors have been typically studied due to the dielectric function that changes with the hydrogen concentration. However, the development of a reliable, integral, and widely applicable hydrogen sensor requires a simple readout mechanism and an optimization of the fast detection of hydrogen. In this work, optical fiber hydrogen sensing platforms are developed using an optimized metasurface, which consists of a layer of palladium nanoantennas array suspended above a gold mirror layer. Since the optical properties of these palladium nanoantennas differ from the traditional palladium films, a high reflectance difference can be achieved when the sensor based on the metasurface is exposed to the hydrogen atmosphere. Finally, the optimized reflectance difference
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 053601 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Efficiency-enhanced reflective nanosieve hologramsOn the CoverSamia Osman Hamid Mohammed, Dong Zhao, Syed Yasir Azeem, Xiaoming Goh, Shawn J. Tan, Jinghua Teng, and Kun Huang
Photon nanosieves, as amplitude-type metasurfaces, have been demonstrated usually in a transmission mode for optical super-focusing, display, and holography, but the sieves with subwavelength size constrain optical transmission, thus leading to low efficiency. Here, we report reflective photon nanosieves that consist of metallic meta-mirrors sitting on a transparent quartz substrate. Upon illumination, these meta-mirrors offer the reflectance of
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 053602 (2022)
Nonlinear Optics
Generation of sub-three-cycle pulses at 53 MHz repetition rate via nonlinear compression in optical parametric oscillatorLixin Yuan, Yu Cai, Yuxi Chu, Jintao Fan, and Minglie Hu
We report an experimental generation of few-cycle pulses at 53 MHz repetition rate. Femtosecond pulses with pulse duration of 181 fs are firstly generated from an optical parametric oscillator (OPO). Then, the pulses are compressed to sub-three-cycle with a hybrid compressor composed of a commercial single-mode fiber and a pair of prisms, taking advantage of the tunability of the OPO and the numerical simulating of the nonlinear compression system. Our compressed optical pulses possess an ultrabroadband spectrum covering over 470 nm bandwidth (at
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 051901 (2022)
Optical Materials
VOx/NaVO3 nanocomposite as a novel saturable absorber for passive Q-switching operationLinghao Kong, Hongwei Chu, Na Li, Han Pan, Shengzhi Zhao, and Dechun Li
We report VOx x x x
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 051601 (2022)
Optical Materials
High laser damage threshold LiNa5Mo9O30 prism: for visible to mid-infrared rangeXiaoli Du, Zeliang Gao, Lijuan Chen, Youxuan Sun, and Xutang Tao
In this study, an excellent polarization optical crystal
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 051602 (2022)
Spectroscopy
Extraction of optical constants in the terahertz band using material dispersion modelsJian Gu, Jiaojiao Ren, Dandan Zhang, and Lijuan Li
This study proposes a method based on material dispersion models to computationally simulate terahertz (THz) time-domain spectroscopy signals. The proposed method can accurately extract the refractive indices and extinction coefficients of optically thin samples and high-absorption materials in the THz band. This method was successfully used to extract the optical constants of a 470-μm-thick monocrystalline silicon sample and eliminate all errors associated with the Fabry–Pérot oscillation. When used to extract the optical constants of a 16.29-mm-thick polycarbonate sample, our method succeeded in minimizing errors caused by the low signal-to-noise ratio in the extracted optical constants.This study proposes a method based on material dispersion models to computationally simulate terahertz (THz) time-domain spectroscopy signals. The proposed method can accurately extract the refractive indices and extinction coefficients of optically thin samples and high-absorption materials in the THz band. This method was successfully used to extract the optical constants of a 470-μm-thick monocrystalline silicon sample and eliminate all errors associated with the Fabry–Pérot oscillation. When used to extract the optical constants of a 16.29-mm-thick polycarbonate sample, our method succeeded in minimizing errors caused by the low signal-to-noise ratio in the extracted optical constants.
Chinese Optics Letters
- Publication Date: May. 10, 2022
- Vol.20 Issue, 5 053001 (2022)
Special Issue on Optical Metasurfaces: Fundamentals and Applications (2022)
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