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 method
Fengdong 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.
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 dicing
Sumei Wang, Jinhua Zhao, Jinjun Gu, Mingyang Bu, Li Fan, Shuang Li, Xifeng Qin, Yicun Yao, Yingying Ren, and Lei Wang
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 fiber
Xinyue 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.
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 imaging
Jiahao Li, Mengwei Cao, Weili Liang, Yilin Zhang, Zhenwei Xie, and Xiaocong Yuan
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 sublimation
Penglong 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.
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 microaxicon
Xiaoying 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.
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 jet
Ye 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.
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 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: 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 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: 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 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: 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 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: Jun. 10, 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: 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 Cover
Zhiyi Xuan, Qingquan Liu, Zhuangzhuang Cui, Songlei Huang, Bo Yang, Chenlu Li, Shaowei Wang, and Wei Lu
Chinese Optics Letters
  • Publication Date: Jun. 10, 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: 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 lasers
Xiaoxu Xing, Xuyan Zhou, Hongwei Qu, Weiqiao Zhang, Lingqian Meng, Jing Liu, Yufei Wang, and Wanhua Zheng
Chinese Optics Letters
  • Publication Date: Jun. 10, 2022
  • Vol.20 Issue, 6 062702 (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: Jun. 10, 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: Jun. 10, 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: 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 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: Jun. 10, 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: 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 method
Chentianfei 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.
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 systems
Gang Chen, Ming Chen, Wen Chen, Lede Yin, Aitao Deng, Yuxin Cai, and Dengqiao Wang
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 laser
Yue Lu, Ziren Zhu, Jinzhou Bai, Xinjun Su, Rongqing Tan, Jinghan Ye, and Yijun Zheng
The spectral linewidth of a transversely excited pulsed CO2 laser is broadened at high working pressures. This phenomenon causes a decrease in the upper-level lifetime such that the pulse width is significantly compressed. Although the tail part of CO2 laser pulses owns a non-negligible proportion of total energy, it has minor effects during the interaction process between photons and materials due to its low amplitude. Thus, it is of great significance to yield the tail part and generate a narrow pulse in most applications. In this study, a continuously tunable pulsed CO2 laser with a low nitrogen proportion in the mixture is developed to generate tail-free short pulses; a minimum pulse width of 30.60 ns with a maximum pulse energy of 481 mJ is synchronously achieved at a pressure of 7 atm, and the estimated peak power is above 15 MW. A numerical simulation is also conducted for comparison with the experimental results. The contribution of the spectral gain toward the compression of the pulse width is discussed in the last section of this paper.
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 fiber
Lei 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 -33.8 dBm and a gain coefficient of 1.9 dB/m. With the utilization of the fiber as a gain medium, a linear-cavity fiber laser has been constructed, which exhibits a signal-to-noise ratio of 74.9 dB at 1596 nm. It has been demonstrated that the fiber laser has a maximum output power of 107.4 mW, a slope efficiency of up to 17.0%, and a linewidth of less than 0.02 nm. Moreover, an all-fiber single-stage optical amplifier is built up for laser amplification, by which the amplified laser power is up to 410.0 mW with pump efficiency of 33.8%. The results indicate that the laser is capable of high signal-to-noise ratio and narrow linewidth, with potential applications for optical fiber sensing, biomedicine, precision measurement, and the pump source of the mid-infrared fiber lasers.
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 tweezers
Lingyao 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.
Chinese Optics Letters
  • Publication Date: May. 10, 2022
  • Vol.20 Issue, 5 053801 (2022)
Microwave Photonics
Unidirectional electromagnetic windmill scattering in a magnetized gyromagnetic cylinder
Jianfeng 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.
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 palladium
Shunshuo 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 ΔR of 0.28 can be obtained when the sensor is exposed in the presence of hydrogen. It is demonstrated that this integrated system architecture with an optimized palladium-based metasurface and a simple optical fiber readout system provides a compact and light platform for hydrogen detection in various working environments.
Chinese Optics Letters
  • Publication Date: May. 10, 2022
  • Vol.20 Issue, 5 053601 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Efficiency-enhanced reflective nanosieve hologramsOn the Cover
Samia 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 50%, which is higher than the transmission of visible light through diameter-identical nanoholes. Benefiting from this configuration, a meta-mirror-based reflective hologram has been demonstrated with good consistence between theoretical and experimental results over the broadband spectrum from 500 nm to 650 nm, meanwhile exhibiting total efficiency of 7%. Additionally, if an additional high-reflectance layer is employed below these meta-mirrors, the efficiency can be enhanced further for optical anti-counterfeiting.
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 oscillator
Lixin 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 -10 dB), and the output intensity fluctuation of our system is less than 0.8%. These results show that our system can effectively generate few-cycle pulses at a repetition rate of tens of megahertz with excellent long-term stability, which could benefit future possible applications.
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 operation
Linghao Kong, Hongwei Chu, Na Li, Han Pan, Shengzhi Zhao, and Dechun Li
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 range
Xiaoli Du, Zeliang Gao, Lijuan Chen, Youxuan Sun, and Xutang Tao
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 models
Jian Gu, Jiaojiao Ren, Dandan Zhang, and Lijuan Li
Chinese Optics Letters
  • Publication Date: May. 10, 2022
  • Vol.20 Issue, 5 053001 (2022)