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Fiber Optics and Optical Communications
Machine vision-based intelligent turbulence perception for underwater wireless optical communication
Yan Jia, Zhitong Huang, Jie Xu, Hongcheng Qiu... and Yuefeng Ji|Show fewer author(s)
Turbulence induced by thermohaline gradient and air bubbles poses a significant challenge to the robustness of underwater wireless optical communication (UWOC) systems. It is imperative to accurately measure the turbulence intensity of the channel to guide the design of adaptive UWOC systems. However, current measurements based on pilot information consume additional spectral resources. We propose a machine vision-based intelligent turbulence perception (MV-ITP) mechanism to measure the turbulence intensity of the underwater channel. The MV-ITP mechanism utilizes the spatiotemporal intrinsic coupling correlation between optical imaging and optical communication to establish a precise quantitative relationship between the pixel intensity variation of the beam images and the scintillation index. We conduct experiments under different turbulence conditions induced by temperature, salinity, as well as air bubbles, and the experimental results demonstrate that the proposed mechanism can accurately measure the intensity of turbulence.Turbulence induced by thermohaline gradient and air bubbles poses a significant challenge to the robustness of underwater wireless optical communication (UWOC) systems. It is imperative to accurately measure the turbulence intensity of the channel to guide the design of adaptive UWOC systems. However, current measurements based on pilot information consume additional spectral resources. We propose a machine vision-based intelligent turbulence perception (MV-ITP) mechanism to measure the turbulence intensity of the underwater channel. The MV-ITP mechanism utilizes the spatiotemporal intrinsic coupling correlation between optical imaging and optical communication to establish a precise quantitative relationship between the pixel intensity variation of the beam images and the scintillation index. We conduct experiments under different turbulence conditions induced by temperature, salinity, as well as air bubbles, and the experimental results demonstrate that the proposed mechanism can accurately measure the intensity of turbulence..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 060601 (2025)
Highly robust and hardware-efficient frame synchronization and carrier recovery via pilot-only approaches for short-reach optical interconnections
Chenchen Wang, Zhipei Li, Ze Dong, Junyuan Song... and Xiangjun Xin|Show fewer author(s)
We propose a cost-effective scheme relying exclusively on pilot symbols for robust frame synchronization and high-precision, wide-range carrier recovery in short-reach optical interconnects. Our method mitigates phase offsets and enhances phase tracking by strategically placing dual-polarization pilot symbols, both aligned and misaligned, within the frame. Compared to traditional carrier recovery schemes, our approach offers a broader frequency offset estimation range, higher carrier recovery accuracy, and significantly lower computational complexity. Experimental results show a 0.7 dB sensitivity improvement at the soft decision forward error correction threshold, outperforming Fourier transform-based frequency offset estimation combined with blind phase search.We propose a cost-effective scheme relying exclusively on pilot symbols for robust frame synchronization and high-precision, wide-range carrier recovery in short-reach optical interconnects. Our method mitigates phase offsets and enhances phase tracking by strategically placing dual-polarization pilot symbols, both aligned and misaligned, within the frame. Compared to traditional carrier recovery schemes, our approach offers a broader frequency offset estimation range, higher carrier recovery accuracy, and significantly lower computational complexity. Experimental results show a 0.7 dB sensitivity improvement at the soft decision forward error correction threshold, outperforming Fourier transform-based frequency offset estimation combined with blind phase search..
Chinese Optics Letters
- Publication Date: May. 19, 2025
- Vol. 23, Issue 6, 060602 (2025)
Magnetic actuation of paramagnetic liquids for optical beam steering in high-speed optical wireless communications
Mithilesh K. Mane, Amjad Ali, Riffat Tehseen, Arfan Mahmood, and Jing Xu
This study examines paramagnetic liquids for optical beam steering in optical wireless communication (OWC) systems. By employing magnetic actuation, effective optical beam control was achieved for both free-space optics (FSO) and underwater wireless optical communication (UWOC). Experimental findings revealed that dysprosium nitrate provided the highest beam steering angles of 5.99° in the ±X direction and 5.73° in the ±Y direction. Additionally, power loss analysis indicated minimal absorption and scattering for dysprosium nitrate and gadolinium nitrate. The system achieved high-speed data rates of 2.1 Gbps for FSO and 1.9 Gbps for UWOC systems, showcasing the promise of this technology.This study examines paramagnetic liquids for optical beam steering in optical wireless communication (OWC) systems. By employing magnetic actuation, effective optical beam control was achieved for both free-space optics (FSO) and underwater wireless optical communication (UWOC). Experimental findings revealed that dysprosium nitrate provided the highest beam steering angles of 5.99° in the ±X direction and 5.73° in the ±Y direction. Additionally, power loss analysis indicated minimal absorption and scattering for dysprosium nitrate and gadolinium nitrate. The system achieved high-speed data rates of 2.1 Gbps for FSO and 1.9 Gbps for UWOC systems, showcasing the promise of this technology..
Chinese Optics Letters
- Publication Date: May. 20, 2025
- Vol. 23, Issue 6, 060603 (2025)
30 Gbps visible light communication in rainy environments based on laser diodes
Yang Xiao, Jiakang Ai, Xiangyang Chen, Xugao Cui, and Pengfei Tian
Rain has a strong attenuation effect on light, which can impact the performance of visible light communication (VLC). In this paper, we addressed the crucial challenge of implementing high-speed VLC systems in rainy environments by focusing on the performance of different wavelengths under varying rain conditions. By analyzing the attenuation characteristics of four laser diodes at different wavelengths under various artificial rain environments, we developed a high-speed VLC system optimized for rainy channel high-speed visible light communication by employing the orthogonal frequency-division multiplexing modulation scheme. By integrating channel-adaptive pre-equalization and bit-loading algorithms, our system optimized signal transmission in rainy channels, enabling an aggregated data rate exceeding 30 Gbps, which was the highest reported data rate for VLC in rainy channels, to the best of our knowledge.Rain has a strong attenuation effect on light, which can impact the performance of visible light communication (VLC). In this paper, we addressed the crucial challenge of implementing high-speed VLC systems in rainy environments by focusing on the performance of different wavelengths under varying rain conditions. By analyzing the attenuation characteristics of four laser diodes at different wavelengths under various artificial rain environments, we developed a high-speed VLC system optimized for rainy channel high-speed visible light communication by employing the orthogonal frequency-division multiplexing modulation scheme. By integrating channel-adaptive pre-equalization and bit-loading algorithms, our system optimized signal transmission in rainy channels, enabling an aggregated data rate exceeding 30 Gbps, which was the highest reported data rate for VLC in rainy channels, to the best of our knowledge..
Chinese Optics Letters
- Publication Date: May. 23, 2025
- Vol. 23, Issue 6, 060604 (2025)
Channel modeling for underwater scattered light communication based on Gaussian and Bessel beams
Yi Gao, Zhitong Huang, Jie Xu, Hongcheng Qiu... and Yuefeng Ji|Show fewer author(s)
Underwater scattered light communication (USLC) utilizes the strong scattering properties of seawater to achieve a non-line-of-sight (NLOS) communication channel, which is a promising solution to the stringent alignment requirements and random transmission path blocking in underwater wireless optical communication. In this Letter, we model the channel for USLC based on Gaussian and Bessel beams, in which we comprehensively explore the effects of different water types and transceiver configurations on USLC and simulate the photon propagation in seawater by Monte Carlo (MC) method. Specifically, we analyze the fluctuation in received signal strength as a function of the communication distance across three distinct water types, in which the model considers the influence of different optical wavelengths and spatial modes at the transmitter as well as various optical lens configurations at the receiver. Modeling and experiments validate blue Gaussian beams for short-range, low-turbidity cases; green Bessel beams for long-range, high-turbidity conditions; and the receiver antenna’s utility which is restricted to short-range applications. The conclusion obtained can be used for the selection of transceiver devices in USLC systems.Underwater scattered light communication (USLC) utilizes the strong scattering properties of seawater to achieve a non-line-of-sight (NLOS) communication channel, which is a promising solution to the stringent alignment requirements and random transmission path blocking in underwater wireless optical communication. In this Letter, we model the channel for USLC based on Gaussian and Bessel beams, in which we comprehensively explore the effects of different water types and transceiver configurations on USLC and simulate the photon propagation in seawater by Monte Carlo (MC) method. Specifically, we analyze the fluctuation in received signal strength as a function of the communication distance across three distinct water types, in which the model considers the influence of different optical wavelengths and spatial modes at the transmitter as well as various optical lens configurations at the receiver. Modeling and experiments validate blue Gaussian beams for short-range, low-turbidity cases; green Bessel beams for long-range, high-turbidity conditions; and the receiver antenna’s utility which is restricted to short-range applications. The conclusion obtained can be used for the selection of transceiver devices in USLC systems..
Chinese Optics Letters
- Publication Date: May. 30, 2025
- Vol. 23, Issue 6, 060606 (2025)
Imaging Systems and Image Processing
Scanning-less optical near-field characterization for structured light fields based on nonlinear effects
Zhenli Li, Rongyi Lin, Min Lin, Luping Du, and Xiaocong Yuan
Conventional methods for near-field characterization have typically relied on the nanoprobe to point-scan the field, rendering the measurements vulnerable to external environmental influences. Here, we study the direct far-field imaging of the near-field polarizations based on the four-wave mixing effect. We construct a simulation model to realize the instantaneous extraction of the near-field distributions of a wide range of structured light fields, such as cylindrical vector vortex beams, plasmonic Weber beams, and topological spin textures, including photonic skyrmions and merons. This method is valuable for the studies on manipulation of structured light fields and light–matter interaction at the micro/nano scales.Conventional methods for near-field characterization have typically relied on the nanoprobe to point-scan the field, rendering the measurements vulnerable to external environmental influences. Here, we study the direct far-field imaging of the near-field polarizations based on the four-wave mixing effect. We construct a simulation model to realize the instantaneous extraction of the near-field distributions of a wide range of structured light fields, such as cylindrical vector vortex beams, plasmonic Weber beams, and topological spin textures, including photonic skyrmions and merons. This method is valuable for the studies on manipulation of structured light fields and light–matter interaction at the micro/nano scales..
Chinese Optics Letters
- Publication Date: May. 23, 2025
- Vol. 23, Issue 6, 061101 (2025)
Instrumentation, Measurement, and Optical Sensing
Absolute linear-angular synchronous positioning at the microscale based on a metasurface array reflector
Wanghang Gu, Junchen Liu, Xueyan Lin, Xinghua Qu, and Fumin Zhang
In this research, we report a two-dimensional pose measurement scheme based on a metasurface array reflector, which enables absolute tracking of both linear and angular positions. The metasurface array reflector, utilizing the tailored optical field characteristics of a plasmonic absorption structure, simultaneously responds to linear and angular displacements within the illuminated optical field range and provides a characteristic absolute code to the receiving end. This code can be used to map the target’s linear and angular position. By matching it with a pre-established template network, it is possible to track the target’s absolute position. Under μm-level linear displacements and μrad-level angular displacements, we achieved precise two-dimensional linear and angular tracking and positioning based on this device.In this research, we report a two-dimensional pose measurement scheme based on a metasurface array reflector, which enables absolute tracking of both linear and angular positions. The metasurface array reflector, utilizing the tailored optical field characteristics of a plasmonic absorption structure, simultaneously responds to linear and angular displacements within the illuminated optical field range and provides a characteristic absolute code to the receiving end. This code can be used to map the target’s linear and angular position. By matching it with a pre-established template network, it is possible to track the target’s absolute position. Under μm-level linear displacements and μrad-level angular displacements, we achieved precise two-dimensional linear and angular tracking and positioning based on this device..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 061201 (2025)
Integrated Optics
532 nm silicon nitride optical phased array and high-speed calibration and control system
Xiaoqun Yu, Zhaoyang Wu, Jinjie Zeng, Shuqing Lin... and Yanfeng Zhang|Show fewer author(s)
Integrated optoelectronic chips working in the visible spectrum range have promising applications in augmented reality and virtual reality, quantum information processing, biosensors, and more. A silicon nitride optical phased array (OPA) can shape and steer light to enable these applications on a compact chip without moving parts. However, smaller wavelength, waveguide size, and the thermo-optic coefficient pose challenges in processing, calibration, and control of silicon nitride OPA chips. In this work, a high-speed phase control system for 532 nm silicon nitride OPA, utilizing a field programmable gate array and a digital-to-analog converter, achieves a 7.4 µs voltage configuration. With this system, the single-shot multivoltage optimization of beam calibration of the OPA for tens of milliseconds is realized, and the beam scanning in the range of ±24° is demonstrated. The system fully meets the needs of high-speed scanning of silicon nitride OPA, advancing OPA’s development and applications.Integrated optoelectronic chips working in the visible spectrum range have promising applications in augmented reality and virtual reality, quantum information processing, biosensors, and more. A silicon nitride optical phased array (OPA) can shape and steer light to enable these applications on a compact chip without moving parts. However, smaller wavelength, waveguide size, and the thermo-optic coefficient pose challenges in processing, calibration, and control of silicon nitride OPA chips. In this work, a high-speed phase control system for 532 nm silicon nitride OPA, utilizing a field programmable gate array and a digital-to-analog converter, achieves a 7.4 µs voltage configuration. With this system, the single-shot multivoltage optimization of beam calibration of the OPA for tens of milliseconds is realized, and the beam scanning in the range of ±24° is demonstrated. The system fully meets the needs of high-speed scanning of silicon nitride OPA, advancing OPA’s development and applications..
Chinese Optics Letters
- Publication Date: May. 27, 2025
- Vol. 23, Issue 6, 061301 (2025)
Lasers, Optical Amplifiers, and Laser Optics
A kilohertz nanosecond 1645 nm KTA-OPO pumped by a 1064 nm pulse laser for methane detection
Hanlin Jiang, Chao Ma, Mingjian Wang, Zhenzhen Yu... and Weibiao Chen|Show fewer author(s)
In this Letter, we studied a kilohertz nanosecond 1645 nm optical parametric oscillator (OPO) for methane detection. The OPO pump source was an electro-optical Q-switched 1064 nm oscillator, followed by a preamplifier and two Innoslab amplifiers. Two KTiOAsO4 crystals with type II angular phase matching were used as the nonlinear working materials, and two plane mirrors were used for the OPO cavity. We achieved the signal light with an average power of 9.32 W and a minimum pulse duration of 1.8 ns at a repetition rate of 8 kHz for a 54.1 W pump power, and the optical-optical conversion efficiency was 17.3%. The beam quality was measured as Mx2 = 1.08 and My2 = 1.22. The wavelength of the signal light was continuously tunable from 1641.9207 to 1648.1791 nm. To the best of our knowledge, this is the highest average power achieved at the kilohertz regime of a 1645 nm laser.In this Letter, we studied a kilohertz nanosecond 1645 nm optical parametric oscillator (OPO) for methane detection. The OPO pump source was an electro-optical Q-switched 1064 nm oscillator, followed by a preamplifier and two Innoslab amplifiers. Two KTiOAsO4 crystals with type II angular phase matching were used as the nonlinear working materials, and two plane mirrors were used for the OPO cavity. We achieved the signal light with an average power of 9.32 W and a minimum pulse duration of 1.8 ns at a repetition rate of 8 kHz for a 54.1 W pump power, and the optical-optical conversion efficiency was 17.3%. The beam quality was measured as Mx2 = 1.08 and My2 = 1.22. The wavelength of the signal light was continuously tunable from 1641.9207 to 1648.1791 nm. To the best of our knowledge, this is the highest average power achieved at the kilohertz regime of a 1645 nm laser..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 061401 (2025)
0.275 THz high-power ultrahigh-repetition-rate pulses in a dissipative fiber ring cavity by ultrafast ignition
Jingmin Liu, Xu Chen, Junjie Jiang, Wenlin Luan, and Xia Yu
We present a novel all-fiber ultrahigh-repetition-rate pulse (UHRP) source based on ultrafast pulse-stimulated dissipative four-wave mixing (FWM). By injecting an ultrafast seed pulse into a dissipative ring cavity equipped with a spectral shaper, a comb-like nonlinear response is generated. The high peak power of the seed pulse reaches the FWM threshold, stimulating a 0.275 THz pulse with an output power of 0.5 W. The gain and spectral shaper in the fiber ring cavity form a dissipative system that modifies the initial field both temporally and spectrally, ensuring UHRP stability even after the pulse is turned off.We present a novel all-fiber ultrahigh-repetition-rate pulse (UHRP) source based on ultrafast pulse-stimulated dissipative four-wave mixing (FWM). By injecting an ultrafast seed pulse into a dissipative ring cavity equipped with a spectral shaper, a comb-like nonlinear response is generated. The high peak power of the seed pulse reaches the FWM threshold, stimulating a 0.275 THz pulse with an output power of 0.5 W. The gain and spectral shaper in the fiber ring cavity form a dissipative system that modifies the initial field both temporally and spectrally, ensuring UHRP stability even after the pulse is turned off..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 061402 (2025)
Quasi-continuous-wave diode-pumped Yb:YCOB monolithic laser with peak power beyond 200 W
Ya Zhou, Fei Liang, Huichen Si, Dazhi Lu... and Huaijin Zhang|Show fewer author(s)
High-power diode-pumped solid-state lasers (DPSSLs) can support many important applications owing to their simple setup and high efficiency. However, the thermal effect in the laser crystal is a major limiting factor for laser power improvement. Here, we originally present a quasi-continuous-wave (QCW) diode-pumped monolithic Yb3+-doped YCa4O(BO3)3 (Yb:YCOB) laser and realize the power scaling at room temperature by removing the heat efficiently. The Yb:YCOB laser at 1024 nm is designed with a quantum efficiency of 95%. A high-power QCW laser is realized with an output peak power of up to 226.7 W, a pulse energy of 12.2 mJ, and an optical-to-optical efficiency of 41.2%. To the best of our knowledge, this result represents the record peak power in Yb:YCOB lasers and should have promising applications in some modern devices requiring high-power and large-energy lasers.High-power diode-pumped solid-state lasers (DPSSLs) can support many important applications owing to their simple setup and high efficiency. However, the thermal effect in the laser crystal is a major limiting factor for laser power improvement. Here, we originally present a quasi-continuous-wave (QCW) diode-pumped monolithic Yb3+-doped YCa4O(BO3)3 (Yb:YCOB) laser and realize the power scaling at room temperature by removing the heat efficiently. The Yb:YCOB laser at 1024 nm is designed with a quantum efficiency of 95%. A high-power QCW laser is realized with an output peak power of up to 226.7 W, a pulse energy of 12.2 mJ, and an optical-to-optical efficiency of 41.2%. To the best of our knowledge, this result represents the record peak power in Yb:YCOB lasers and should have promising applications in some modern devices requiring high-power and large-energy lasers..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 061403 (2025)
Dynamic coherence control of random lasers and its effect on speckle and edge sharpness of images
Zhihao Li, Jianghao Li, Yanyan Huo, Yangjian Cai, and Yuan Wan
In this Letter, we designed a random laser based on a nematic liquid crystal with titanium nitride nanoparticles, which has low spatial coherence, and its spatial coherence can be dynamically manipulated by the applied voltage. In a scattering environment, the speckle effect can be effectively suppressed using the random laser as the light source, and the speckle degree is controlled by the applied voltage. Moreover, with the decrease of the spatial coherence of the random laser, the imaging edges become blurred. We provided a quantitative way to optimize the image quality between uniformity and edge sharpness while improving the signal-to-noise ratio.In this Letter, we designed a random laser based on a nematic liquid crystal with titanium nitride nanoparticles, which has low spatial coherence, and its spatial coherence can be dynamically manipulated by the applied voltage. In a scattering environment, the speckle effect can be effectively suppressed using the random laser as the light source, and the speckle degree is controlled by the applied voltage. Moreover, with the decrease of the spatial coherence of the random laser, the imaging edges become blurred. We provided a quantitative way to optimize the image quality between uniformity and edge sharpness while improving the signal-to-noise ratio..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 061404 (2025)
High-energy and high-peak-power Q-switched Er3+/Dy3+-codoped fluoride fiber oscillator aiming at a 2.94 µm water absorption peak
Xiangyu Zhao, Hongyu Luo, Jianfeng Li, and Yong Liu
In this Letter, we demonstrate high-energy and high-peak-power nanosecond pulse generation aiming at the 2.94 µm water absorption peak, from a 980 nm diode-clad-pumped actively Q-switched Er3+/Dy3+-codoped fluoride fiber oscillator. Operating at the 2943 nm wavelength locked by a diffraction grating in a Littrow configuration, stable Q-switching with the shortest temporal width of 41 ns has been obtained at a low repetition rate of 100 Hz. The maximum pulse energy of 108 µJ and peak power of 2.48 kW are primarily limited by the thermal damage of the bare fluoride fiber facet for pump coupling and represent the records of pulsed fiber oscillators around 2.94 µm, to the best of our knowledge. This advanced nanosecond laser source provides an optional promising tool for laser medical applications.In this Letter, we demonstrate high-energy and high-peak-power nanosecond pulse generation aiming at the 2.94 µm water absorption peak, from a 980 nm diode-clad-pumped actively Q-switched Er3+/Dy3+-codoped fluoride fiber oscillator. Operating at the 2943 nm wavelength locked by a diffraction grating in a Littrow configuration, stable Q-switching with the shortest temporal width of 41 ns has been obtained at a low repetition rate of 100 Hz. The maximum pulse energy of 108 µJ and peak power of 2.48 kW are primarily limited by the thermal damage of the bare fluoride fiber facet for pump coupling and represent the records of pulsed fiber oscillators around 2.94 µm, to the best of our knowledge. This advanced nanosecond laser source provides an optional promising tool for laser medical applications..
Chinese Optics Letters
- Publication Date: May. 26, 2025
- Vol. 23, Issue 6, 061405 (2025)
Microwave Photonics
Photonics-enabled broadband continuous-wave terahertz computed tomography
Zuomin Yang, Lu Zhang, Zhidong Lü, Xing Fang, and Xianbin Yu
In this paper, we propose a photonic terahertz (THz) continuous-wave computed tomography (CT) system employing an optical frequency comb and specialized imaging algorithms. Our work leverages the system to offer unique advantages in detecting and analyzing samples that are challenging for traditional 2D scanning systems. Our experimental results, operating at 330 GHz, reach an exceptionally low amplitude standard deviation of 0.016 mV. Additionally, the proposed system performs nondestructive CT detection with a 0.5 mm error margin and obtains enhanced image quality, showing its great promise for implementing THz-CT imaging with high robustness and resolution.In this paper, we propose a photonic terahertz (THz) continuous-wave computed tomography (CT) system employing an optical frequency comb and specialized imaging algorithms. Our work leverages the system to offer unique advantages in detecting and analyzing samples that are challenging for traditional 2D scanning systems. Our experimental results, operating at 330 GHz, reach an exceptionally low amplitude standard deviation of 0.016 mV. Additionally, the proposed system performs nondestructive CT detection with a 0.5 mm error margin and obtains enhanced image quality, showing its great promise for implementing THz-CT imaging with high robustness and resolution..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 063901 (2025)
Nanophotonics, Metamaterials, and Plasmonics
Compact nanohole/disk array-based plasmonic fiber-optic end-facet sensing probe: batch preparation and performance determination
Yijin He, Yuzhang Liang, Xinran Wei, Yuqi Du... and Wei Peng|Show fewer author(s)
A gold nanohole/disk array-based plasmonic fiber end-facet sensing probe is proposed and demonstrated experimentally, where the hybrid plasmon mode on the top surface used for sensing is excited by the cooperative effect of the near-field coupling between the nanohole and the nanodisk, as well as the localized surface plasmon of the nanodisk. The high-quality integration of the nanohole/disk array on the fiber end facet is achieved by combining nanoimprint lithography on a planar substrate with fiber ultraviolet (UV)-curable adhesive transfer techniques. As a result, the fabricated fiber probe experimentally exhibits a moderately high bulk refractive index sensitivity of ∼196.91 nm/RIU and excellent surface sensitivity. Furthermore, the specific identification and determination of protein molecules verify their sensitivity analysis capabilities for future bioassays. This work provides a feasible plasmonic excitation strategy and enables batch-manufactured technology for nanostructure-based fiber probes to break through the current bottlenecks in biosensing applications.A gold nanohole/disk array-based plasmonic fiber end-facet sensing probe is proposed and demonstrated experimentally, where the hybrid plasmon mode on the top surface used for sensing is excited by the cooperative effect of the near-field coupling between the nanohole and the nanodisk, as well as the localized surface plasmon of the nanodisk. The high-quality integration of the nanohole/disk array on the fiber end facet is achieved by combining nanoimprint lithography on a planar substrate with fiber ultraviolet (UV)-curable adhesive transfer techniques. As a result, the fabricated fiber probe experimentally exhibits a moderately high bulk refractive index sensitivity of ∼196.91 nm/RIU and excellent surface sensitivity. Furthermore, the specific identification and determination of protein molecules verify their sensitivity analysis capabilities for future bioassays. This work provides a feasible plasmonic excitation strategy and enables batch-manufactured technology for nanostructure-based fiber probes to break through the current bottlenecks in biosensing applications..
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 063601 (2025)
Optical performances of near-infrared metalenses with process-induced defects
Xiaofei Liu, Ruohui Chen, Yilin Lu, Chenxu Zhu... and Ting Hu|Show fewer author(s)
Defects are inevitably induced during the fabrication process of a metalens, which will affect the metalens’s yield and optical performances. Thus, investigations on the fabrication defects are becoming increasingly important for the mass production of metalenses. In this Letter, the optical performances of near-infrared metalenses with four types of fabrication defects are investigated. The results show that the process-induced defects obviously affect the focusing efficiency at λ = 940 nm, but they have less impact on the quality of the focal spot. This work provides fabrication guidance for large-scale manufacturing of metalenses in the future.Defects are inevitably induced during the fabrication process of a metalens, which will affect the metalens’s yield and optical performances. Thus, investigations on the fabrication defects are becoming increasingly important for the mass production of metalenses. In this Letter, the optical performances of near-infrared metalenses with four types of fabrication defects are investigated. The results show that the process-induced defects obviously affect the focusing efficiency at λ = 940 nm, but they have less impact on the quality of the focal spot. This work provides fabrication guidance for large-scale manufacturing of metalenses in the future..
Chinese Optics Letters
- Publication Date: May. 26, 2025
- Vol. 23, Issue 6, 063602 (2025)
Generation of arbitrary vector vortex beams on the hybrid-order Poincaré sphere from cholesteric liquid crystals
Tiegang Lin, Ben Niu, Furong Liu, Xianglin Ye... and Yufang Liu|Show fewer author(s)
In this Letter, by exploiting the spin-to-orbital angular momentum conversion capability and the polarization selectivity characteristic of cholesteric liquid crystal planar optical elements, an approach of combing two cholesteric liquid crystal layers with opposite handedness and independent surface patterns is proposed and investigated for generating arbitrary vector vortex beams on the hybrid-order Poincaré sphere. Furthermore, the intensity profiles and polarization distributions of typical vector vortex beams are experimentally demonstrated and analyzed, which shows good agreement with the theoretical prediction. The approach also suggests its advantages of operating light in the polychromatic spectral region of Bragg reflection. Our method presents a simple and direct way of phase and polarization manipulation, which also provides promising opportunities for developing advanced applications in structured light, high-resolution imaging, and information processing.In this Letter, by exploiting the spin-to-orbital angular momentum conversion capability and the polarization selectivity characteristic of cholesteric liquid crystal planar optical elements, an approach of combing two cholesteric liquid crystal layers with opposite handedness and independent surface patterns is proposed and investigated for generating arbitrary vector vortex beams on the hybrid-order Poincaré sphere. Furthermore, the intensity profiles and polarization distributions of typical vector vortex beams are experimentally demonstrated and analyzed, which shows good agreement with the theoretical prediction. The approach also suggests its advantages of operating light in the polychromatic spectral region of Bragg reflection. Our method presents a simple and direct way of phase and polarization manipulation, which also provides promising opportunities for developing advanced applications in structured light, high-resolution imaging, and information processing..
Chinese Optics Letters
- Publication Date: May. 30, 2025
- Vol. 23, Issue 6, 063603 (2025)
Nonlinear Optics
Giant enhancement of second-harmonic generation from microcavity-integrated monolayer WS2
Boyu Xu, Xiao Xiong, Rui Niu, Guangyuan Qu... and Xifeng Ren|Show fewer author(s)
Transition metal dichalcogenide two-dimensional (2D) materials, exhibiting extraordinary properties absent in their bulk forms, have garnered significant attention in the field of nonlinear optical devices. However, the atomic-level thickness limits the light absorption, which makes the intensity of the nonlinear signal extremely weak. Through transferring monolayer WS2 onto a silica microsphere, we report a giant second-harmonic generation (SHG) enhancement for approximately 1.46 × 107 times. The second-harmonic (SH) signal reaches 2.56 MHz pumped by a continuous wave laser of 2.5 mW. It is attributed to an enhancement of the pump laser due to the whispering gallery mode of the microsphere cavity. This work demonstrates the potential of microcavity-integrated monolayer 2D materials for nonlinear optics in integrated photonics.Transition metal dichalcogenide two-dimensional (2D) materials, exhibiting extraordinary properties absent in their bulk forms, have garnered significant attention in the field of nonlinear optical devices. However, the atomic-level thickness limits the light absorption, which makes the intensity of the nonlinear signal extremely weak. Through transferring monolayer WS2 onto a silica microsphere, we report a giant second-harmonic generation (SHG) enhancement for approximately 1.46 × 107 times. The second-harmonic (SH) signal reaches 2.56 MHz pumped by a continuous wave laser of 2.5 mW. It is attributed to an enhancement of the pump laser due to the whispering gallery mode of the microsphere cavity. This work demonstrates the potential of microcavity-integrated monolayer 2D materials for nonlinear optics in integrated photonics..
Chinese Optics Letters
- Publication Date: May. 23, 2025
- Vol. 23, Issue 6, 061901 (2025)
Optical Materials
39 Influence of defect anisotropy on luminescence properties in Pr:YAP crystals
Lu Zhang, Bowen Jiang, Mingyan Pan, Weiguo Ji... and Hongji Qi|Show fewer author(s)
This study aims to investigate the anisotropic properties of Pr:YAP on (100), (010), and (001) crystal planes. Raman spectroscopy shows anisotropy in vibrational modes, but absorption spectra display no significant anisotropy. X-ray excited luminescence (XEL) and photoluminescence (PL) spectra reveal anisotropy in Pr3+ and F+ luminescence intensities. The PL decay time (∼7 ns) indicates similar luminescence mechanisms. The anisotropic defect distribution observed in thermoluminescence analysis can be explained using areal ion density and the offset parameter of Al atoms. Ultimately, it is inferred that shallow-level defects compete with Pr3+ ions, leading to variations in anisotropic luminescence intensity.This study aims to investigate the anisotropic properties of Pr:YAP on (100), (010), and (001) crystal planes. Raman spectroscopy shows anisotropy in vibrational modes, but absorption spectra display no significant anisotropy. X-ray excited luminescence (XEL) and photoluminescence (PL) spectra reveal anisotropy in Pr3+ and F+ luminescence intensities. The PL decay time (∼7 ns) indicates similar luminescence mechanisms. The anisotropic defect distribution observed in thermoluminescence analysis can be explained using areal ion density and the offset parameter of Al atoms. Ultimately, it is inferred that shallow-level defects compete with Pr3+ ions, leading to variations in anisotropic luminescence intensity..
Chinese Optics Letters
- Publication Date: May. 30, 2025
- Vol. 23, Issue 6, 061601 (2025)
Optoelectronics
High-performance broadband photodetectors based on b-As0.5P0.5 for infrared optical communication and imaging
Qianli Ma, Yiheng Li, Dawei He, Yongsheng Wang, and Yajie Yang
Infrared (IR) photodetectors (PDs) are crucial for medical imaging, optical communication, security surveillance, remote sensing, and gas identification. In this Letter, we systematically investigated a room temperature IR PD based on two-dimensional b-As0.5P0.5, a relatively unexplored component of b-AsP alloys. We synthesized high-quality b-As0.5P0.5 flakes via the chemical vapor transport (CVT) method with precisely controlled conditions. The fabricated b-As0.5P0.5 PD exhibits excellent photoconductivity, high responsivity, and a fast response in the visible and near-infrared (Vis-NIR) band. It achieves a responsivity of ∼0.209 A·W-1 and a response time of ∼16.6 µs under 1550 nm IR illumination. High-resolution single-pixel point optical imaging and high-speed optical communication were realized by the b-As0.5P0.5 PDs. This study confirms that b-As0.5P0.5 materials are highly promising for advanced IR optoelectronic applications.Infrared (IR) photodetectors (PDs) are crucial for medical imaging, optical communication, security surveillance, remote sensing, and gas identification. In this Letter, we systematically investigated a room temperature IR PD based on two-dimensional b-As0.5P0.5, a relatively unexplored component of b-AsP alloys. We synthesized high-quality b-As0.5P0.5 flakes via the chemical vapor transport (CVT) method with precisely controlled conditions. The fabricated b-As0.5P0.5 PD exhibits excellent photoconductivity, high responsivity, and a fast response in the visible and near-infrared (Vis-NIR) band. It achieves a responsivity of ∼0.209 A·W-1 and a response time of ∼16.6 µs under 1550 nm IR illumination. High-resolution single-pixel point optical imaging and high-speed optical communication were realized by the b-As0.5P0.5 PDs. This study confirms that b-As0.5P0.5 materials are highly promising for advanced IR optoelectronic applications..
Chinese Optics Letters
- Publication Date: May. 19, 2025
- Vol. 23, Issue 6, 062501 (2025)
Physical Optics
Generation and manipulation of multiple multidimensional perfect Poincaré beams enabled by a single-layer all-dielectric geometric metasurface
Ximin Tian, Shenglan Zhang, Yaning Xu, Junwei Xu... and Zhi-Yuan Li|Show fewer author(s)
Perfect Poincaré beams (PPBs) are highly esteemed for their topological charge-independent radius and intensity profile. However, the generation and manipulation of PPBs typically involve two-dimensional planes perpendicular to the optical axis, hindering broader usability. Here, leveraging a single-layer all-dielectric geometric metasurface platform, we numerically showcase the generation and manipulation of multiple multidimensional PPBs. Multiple dimensions of PPBs, involving orbital angular momentum (OAM), polarization state, and three-dimensional (3D) spatial propagation, can be manipulated independently via tailoring topological charges assigned to two orthogonal perfect vortex beam (PVB) components, varying initial phase difference and amplitude ratios between two orthogonal PVB components, and strategizing 3D propagation trajectories. To demonstrate the feasibility of the recipe, two metasurfaces are designed: one is for generating an array of PPBs with tailored polarization states along cylindrical helical trajectories, and the other is for creating dual arrays of PPBs with personalized OAM and polarization eigenstates across two misaligned focal planes. As a proof-of-concept illustration, we showcase an optical information encryption scheme through a single metasurface encoding personalized polarization states and OAM in parallel channels of multiple PPBs. This work endeavors to establish an ultra-compact platform for generating and manipulating multiple PPBs, potentially advancing their applications in optical encryption, particle manipulation, and quantum optics.Perfect Poincaré beams (PPBs) are highly esteemed for their topological charge-independent radius and intensity profile. However, the generation and manipulation of PPBs typically involve two-dimensional planes perpendicular to the optical axis, hindering broader usability. Here, leveraging a single-layer all-dielectric geometric metasurface platform, we numerically showcase the generation and manipulation of multiple multidimensional PPBs. Multiple dimensions of PPBs, involving orbital angular momentum (OAM), polarization state, and three-dimensional (3D) spatial propagation, can be manipulated independently via tailoring topological charges assigned to two orthogonal perfect vortex beam (PVB) components, varying initial phase difference and amplitude ratios between two orthogonal PVB components, and strategizing 3D propagation trajectories. To demonstrate the feasibility of the recipe, two metasurfaces are designed: one is for generating an array of PPBs with tailored polarization states along cylindrical helical trajectories, and the other is for creating dual arrays of PPBs with personalized OAM and polarization eigenstates across two misaligned focal planes. As a proof-of-concept illustration, we showcase an optical information encryption scheme through a single metasurface encoding personalized polarization states and OAM in parallel channels of multiple PPBs. This work endeavors to establish an ultra-compact platform for generating and manipulating multiple PPBs, potentially advancing their applications in optical encryption, particle manipulation, and quantum optics..
Chinese Optics Letters
- Publication Date: May. 22, 2025
- Vol. 23, Issue 6, 062601 (2025)