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Fiber‑Optic Microfiber:Tracking Activity Enhancement and Suppression of Heterogeneous Photocatalysts

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Advanced Fiber Materials 2023年第2期5卷 527-542页

作者： Yunyun Huang Jiaxuan Liang Pengwei Chen Jiaxin Wan Haotian Wu Xiaolan Wu Aoxiang Xiao bai‑ou guan Jinan University Guangzhou 511400China guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 511443China

Obtaining detailed insight into the photocatalytic performance of heterogeneous photocatalytic materials,is important for evaluating material properties as well as guiding material design.However,capture of the detailed matter changes on a photocatalyst surface in real time,and in situ during photocatalysis remains challenging.This work reports a promising optical microfiber sensor integrating a photocatalytic reaction monolayer on an optical microfiber surface to monitor reaction kinetics using Cu_(2)O-based heterogeneous photocatalysts,as an example.The evanescent field of microfiber is used to track the photocatalytic process in real time,through the interaction with the catalytic layer,by monitoring the surface refractive index changes caused by adsorption and degradation.Since the catalytic layer is less than 1µm thick,the typical high-power light source can be replaced by low-power light irradiation.This method successfully reveals that relative to the pristine Cu_(2)O microspheres,the photocatalytic activity is enhanced by the incorporation of Ti_(3)C_(2)T_(x) MXene into Cu_(2)O,whereas incorporation of CdS into Cu_(2)O suppresses the activity.Compared with the existing methods used for photocatalysis evalu-ation,this optical microfiber can be directly employed in real matrices to track local photocatalytic performance.It can also provide details about the different adsorption/degradation kinetics of photocatalysts.It is suitable for most photocatalytic processes and is not limited to pollutants with characteristic UV–visible absorption spectra.This study provides important inspiration for the future development of in situ,real-time reaction assessment.

关键词： Photocatalysis around microfiber Tracking Heterogeneous photocatalysts Activity enhancement Suppression

Improvement in resolution of fiber-laser photoacoustic tomography based on a virtual-point concept

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Visual Computing for Industry,Biomedicine,and Art 2021年第1期4卷 22-28页

作者： Xue bai Xu Li Jun Ma bai-ou guan guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 511443China

In this study,a virtual-point concept was introduced into fiber-laser photoacoustic tomography to improve the elevational image resolution.The flexible fiber laser was bent into an arc shape to conform to the ultrasound wavefront,which formed an ultrasound focus at the center of the arc.The synthetic aperture focusing technique was utilized to reconstruct the images;as a result,the elevational resolution particularly within the out-of-focus region was considerably improved compared to the resolution of an image retrieved by multiplexing the PA time-resolved signals with sound velocity.The all-optical fiber-laser photoacoustic tomography system with a high spatial resolution has potential for various applications,including biomedical research and preclinical/clinical diagnosis.

关键词： Photoacoustic tomography Fiber laser Virtual point Synthetic aperture focusing

Miniature Fiber-Optic Magnetic Field Sensor Based on Ampere Force and Fiber Laser

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Photonic Sensors 2020年第4期10卷 291-297页

作者： Weiren CHENG Tianming LUO Linghao CHENG Hao LIANG bai-ou guan Institute of Photonics Technology Jinan UniversityGuangzhou 510632China

A compact fiber-optic magnetic field sensor is proposed by packaging an orthogonal dual-frequency fiber grating laser and a copper wire with alternating electrical current together inside epoxy resin.The alternating current generates Ampere force in a magnetic field,which changes the birefringence of the fiber laser and hence tunes the frequency of the beat signal after photodetection.The magnetic flux density can then be detected by measuring the frequency change of the beat signal.The sensitivity of the sensor can be tuned with a maximum response of 35.21 kHz/kGs demonstrated.Moreover,the sensor shows good immunity to environment interference.

关键词： Fiber laser optical magnetic field sensors fiber-optic sensors Ampere force

Polarimetric parity-time symmetry in a photonic system

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Light(Science & Applications) 2020年第1期9卷 390-397页

作者： Lingzhi Li Yuan Cao Yanyan Zhi Jiejun Zhang Yuting Zou Xinhuan Feng bai-ou guan Jianping Yao guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 511442China Microwave Photonics Research Laboratory School of Electrical Engineering and Computer ScienceUniversity of OttawaOttawaON K1N 6N5Canada

Parity-time(PT)symmetry has attracted intensive research interest in recent years.PT symmetry is conventionally implemented between two spatially distributed subspaces with identical localized eigenfrequencies and complementary gain and loss coefficients.The implementation is complicated.In this paper,we propose and demonstrate that PT symmetry can be implemented between two subspaces in a single spatial unit based on optical polarimetric diversity.By controlling the polarization states of light in the single spatial unit,the localized eigenfrequencies,gain,loss,and coupling coefficients of two polarimetric loops can be tuned,leading to PT symmetry breaking.As a demonstration,a fiber ring laser based on this concept supporting stable and single-mode lasing without using an ultranarrow bandpass filter is implemented.

关键词： polarization symmetry Polar

Brillouin Scattering Spectrum Analysis Based on Auto-Regressive Spectral Estimation

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Photonic Sensors 2018年第2期8卷 114-118页

作者： Mengyun HUANG Wei LI Zhangyun LIU Linghao CHENG bai-ou guan guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics Technology Jinan University Guangzhou 510632 China

汽车回归(AR ) 光谱评价技术被建议分析在 Brillouin 光时间域 refelectometry 散布光谱的 Brillouin。它显示出基于的方法能可靠地估计的那 AR 如果数据长度不是太短的，有比快 Fourier 变换(快速傅里叶变换) 好一些的精确性的 Brillou... 详细信息

汽车回归(AR ) 光谱评价技术被建议分析在 Brillouin 光时间域 refelectometry 散布光谱的 Brillouin。它显示出基于的方法能可靠地估计的那 AR 如果数据长度不是太短的，有比快 Fourier 变换(快速傅里叶变换) 好一些的精确性的 Brillouin 频率移动基于方法。它在一个中等空间决定在快速傅里叶变换上启用大约 3 次改进。

关键词：光谱分析评价技术散布回归汽车快速傅里叶变换 Fourier 数据长度

Flexible microbubble-based Fabry-Pérot cavity for sensitive ultrasound detection and wide-view photoacoustic imaging

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Photonics Research 2020年第10期8卷 1558-1565页

作者： JUN MA YANG HE XUE bai LI-PENG SUN KA CHEN KYUNGHWAN OH bai-ou guan guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 511443China Photonic Device Physics Laboratory Department of PhysicsYonsei UniversitySeoul 033722South Korea

Interaction of acoustic waves and microbubbles occurs in numerous biomedical applications including ultrasound imaging,drug delivery,lithotripsy treatment,and cell manipulation,wherein the acoustically driven microbub-blcs routincly act as active microscale oscillators or actuators.In contrast,microbubbles were utilized here as passive reccivers to detect broadband ultrasound waves in aqueous environments.The microbubble was photo-thermally generated on a microstructured optical fiber(MOF)tip,forming a flexible Fabry-Perot cavity whose gas-water interface was sensitive to ultrasound waves.The MOF severed as both a low-loss waveguide and a compact light condenser,allowing high-efficiency generation and stabilization of ultrasmall microbubbles.Integrated with all-fiber interferometry,a 10 um diameter microbubble exhibited a low noise-cquivalcnt pressur elevei of^3.4 mPa/Hz^1/2 and a broad bandwidth of^0.8 MHz,capable of detecting weak ultrasounds emittedfrom red blood cells irradiated by pulsed laser light.With advantages of high sensitivity,compact size,and low cost,the microbubble-based ultrasound sensor has great potential in biomedical imaging and sensing applications.

关键词： microstructure bubble cavity

Low-Frequency Vibration Measurement by a Dual-Frequency DBR Fiber Laser

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Photonic Sensors 2017年第3期7卷 206-210页

作者： Bing ZHANG Linghao CHENG Yizhi LIANG Long JIN Tuan GUO bai-ou guan guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics Technology Jinan University Guangzhou 510632 China

双频率的分布式的布拉格反射镜(DBR ) 纤维激光基于传感器通过 Doppler 效果为低频率的颤动测量被表明。建议传感器的反应是相当线性的并且比一张常规加速表的高得多。建议传感器能工作在下面到有高敏感的 1 Hz。因此，建议传感器在低... 详细信息

双频率的分布式的布拉格反射镜(DBR ) 纤维激光基于传感器通过 Doppler 效果为低频率的颤动测量被表明。建议传感器的反应是相当线性的并且比一张常规加速表的高得多。建议传感器能工作在下面到有高敏感的 1 Hz。因此，建议传感器在低频率的颤动测量是很有效的。

关键词：光纤激光器振动测量 DBR 双频率低频激光传感器分布布拉格反射多普勒效应

Arbitrary polarization conversion dichroism metasurfaces for all-in-one full Poincare sphere polarizers

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Light(Science & Applications) 2021年第2期10卷 208-216页

作者： Shuai Wang Zi-Lan Deng Yujie Wang Qingbin Zhou Xiaolei Wang Yaoyu Cao bai-ou guan Shumin Xiao Xiangping Li guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan University510632 GuangzhouChina Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System Harbin Institute of Technology518055 ShenzhenChina Institute of Modern Optics Nankai University300350 TianjinChina

The control of polarization,an essential property of light,is of broad scientific and technological interest.Polarizers are indispensable optical elements for direct polarization generation.However,arbitrary polarization generation,except that of common linear and circular polarization,relies heavily on bulky optical components such as cascading linear polarizers and waveplates.Here,we present an effective strategy for designing all-in-one full Poincare sphere polarizers based on perfect arbitrary polarization conversion dichroism and implement it in a monolayer all-dielectric metasurface.This strategy allows preferential transmission and conversion of one polarization state located at an arbitrary position on the Poincare sphere to its handedness-flipped state while completely blocking its orthogonal state.In contrast to previous methods that were limited to only linear or circular polarization,our method manifests perfect dichroism of nearly 100%in theory and greater than 90%experimentally for arbitrary polarization states.By leveraging this attractive dichroism,our demonstration of the generation of polarization beams located at an arbitrary position on a Poincare sphere directly from unpolarized light can substantially extend the scope of meta-optics and dramatically promote state-of-the-art nanophotonic devices.

关键词： surface. Poincare arbitrary

Dual-shot dynamics and ultimate frequency of all-optical magnetic recording on GdFeCo

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Light(Science & Applications) 2021年第1期10卷 98-105页

作者： Sicong Wang Chen Wei\Yuanhua Feng Hongkun Cao Wenzhe Li Yaoyu Cao bai-ou guan Arata Tsukamoto Andrei Kirilyuk Alexey VKimel Xiangping Li guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications Institute of Photonics TechnologyJinan UniversityGuangzhou 510632China Institute for Molecules and Materials Radboud UniversityHeyendaalseweg 1356525 AJ NijmegenThe Netherlands Department of Electronic Engineering College of Information Science and TechnologyJinan UniversityGuangzhou 510632China Institute of New Energy Technology Department of Electronic EngineeringCollege of Information Science and TechnologyJinan UniversityGuangzhou 510632China College of Science and Technology Nihon University7-24-1 FunabashiChiba 274-8501Japan FELIX Laboratory Radboud UniversityToernooiveld 76525 ED NijmegenThe Netherlands

Although photonics presents the fastest and most energy-efficient method of data transfer,magnetism still offers the cheapest and most natural way to store data.The ultrafast and energy-efficient optical control of magnetism is presently a missing technological link that prevents us from reaching the next evolution in information processing.The discovery of all-optical magnetization reversal in GdFeCo with the help of 100fs laser pulses has further aroused intense interest in this compelling problem.Although the applicability of this approach to high-speed data processing depends vitally on the maximum repetition rate of the switching,the latter remains virtually unknown.Here we experimentally unveil the ultimate frequency of repetitive all-optical magnetization reversal through time-resolved studies of the dual-shot magnetization dynamics in Gd27 Fe63.87 C09.T3.Varying the intensities of the shots and the shotto-shot separation,we reveal the conditions for ultrafast writing and the fastest possible restoration of magnetic bits.It is shown that although magnetic writing launched by the first shot is completed after 100 ps,a reliable rewriting of the bit by the second shot requires separating the shots by at least 300 ps.Using two shots partially overlapping in space and minimally separated by 300 ps,we demonstrate an approach for GHz magnetic writing that can be scaled down to sizes below the diffraction limit.

关键词： magnetic dynamics recording