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Reconfigurable time-stretched swept laser source with up to 100 MHz sweep rate,100 nm bandwidth,and 100 mm OCT imaging range

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photonics Research 2020年第8期8卷 1360-1367页

作者： DONGMEI HUANG FENG LI CHAO SHANG ZIHAO CHENG p.k.a.wai photonics Research Centre Department of Electronic and Information EngineeringThe Hong Kong Polytechnic UniversityHong Kong SARChina The Hong kong polytechnic University Shenzhen Research Institute Shenzhen 518057China photonics Research Centre Department of Electrical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SARChina key Laboratory of Luminescence and Optical Information Ministry of EducationSchool of ScienceBeijing Jiaotong UniversityBeijing 100044China

The sweep rate,sweep range,and coherence length of swept sources,respectively,determine the acquisition rate,axial resolution,and imaging range of optical coherence tomography(OCT).In this paper,we demonstrate a reconfigurable high-speed and broadband swept laser by time stretching of a flat spectrum femtosecond pulse train with over 100 nm bandwidth and a repetition rate of 100 *** incorporating an optical modulator and utilizing appropriate dispersive modules,the reconfiguration of the swept source is demonstrated with sweep rates of 25 and 2.5 *** 2.5 MHz swept source enables an imaging range of>110 mm with 6 dB sensitivity rolloff in OCT,which is the longest imaging range ever reported for megahertz OCT.

关键词： laser modulator source

Studies on nonlinear loss and laser dynamics:from multiwavelength CW lasing to multi-pulsing transition

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Studies on nonlinear loss and laser dynamics:from multiwavel...

2010亚洲光电子会议光电器件及其集成分会场

作者： J.Nathan kutz p.k.a.wai Department of Applied Mathematics University of Washington photonics Research Centre Department of Electronics and Information EngineeringThe Hong Kong Polytechnic University

We develop a simple iterative model to simulate a laser with homogeneous gain and intensity dependent loss. Simulation results show that a laser with homogenous gain can operate at multiple wavelengths if the intensity-dependent loss exhibits saturable transmitter characteristics. Our results also show that for nonlinear losses that have both saturable transmitter and saturable absorber characteristics, such as arises from nonlinear optical loss mirrors (NOLM) or nonlinear polarization rotation (NpR), the multiwavelength output power spectrum can become very flat. The laser can also exhibit periodic and chaotic behaviors. We find that the same theoretical model can also be used to describe multi- pulsing dynamics of mode-locked lasers when the cavity energy increases. Near the multi-pulsing transitions, both periodic and chaotic behavior can be observed as operating states of the laser cavity. Our iterative model provides a simple geometrical description of the entire multi-pulsing transition behavior as a function of increasing cavity energy. The model captures all the key features observed in experiments, including the periodic and chaotic mode-locking regions, and further provides valuable insight into laser cavity engineering for maximizing performance.

关键词： Multiwavelength laser Nonlinear loss Mode-locking Multi-pulsing Discrete model Chaos

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多波长Raman光纤激光器

多波长Raman光纤激光器

Interplay of laser power and pore characteristics in selective laser melting of Zk60 magnesium alloys:A study based on in-situ monitoring and image analysis

中国光学学会2006年学术大会

作者：许立新 p.k.a.wai k．F．Lui H．Y.Tam 明海香港理工大学工程学院香港理工大学工程学院香港理工大学工程学院香港理工大学工程学院中国科学技术大学光子技术研究所

＜正＞多波长光纤激光光源在光纤通信以及光纤传感中均有着重要的应用前景,引起了研究者的极大兴趣。多波长激光光源的基本结构是采用增益介质与梳状滤波器组成,增益介质采用稀土掺杂光纤、半导体放大器（SOA）或光纤非线性（SBS、SRS）...

＜正＞多波长光纤激光光源在光纤通信以及光纤传感中均有着重要的应用前景,引起了研究者的极大兴趣。多波长激光光源的基本结构是采用增益介质与梳状滤波器组成,增益介质采用稀土掺杂光纤、半导体放大器（SOA）或光纤非线性（SBS、SRS）等,采用稀土掺杂光纤或半导体放大器（SOA）作为增益介质时,由于均匀展宽介质的特性,使得各个波长之间存在着增益竞争,因而出现了各个波长输出功率的不稳定现象。利用光纤SRS非线性效应提供增益的多波长光纤激光器,由于非均匀展宽增益特性,使得

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Journal of Magnesium and Alloys 2024年第4期12卷 1346-1366页

作者： Weijie Xie Hau-Chung Man Chi-wai Chan Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong KongChina School of Mechanical and Aerospace Engineering Queen’s UniversityBelfast BT95AHUK Research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHong KongChina

This study offers significant insights into the multi-physics phenomena of the SLM process and the subsequent porosity characteristics of Zk60 Magnesium(Mg)***-speed in-situ monitoring was employed to visualise process signals in real-time,elucidating the dynamics of melt pools and vapour plumes under varying laser power conditions specifically between 40 W and 60 *** morphological analysis was performed using Scanning-Electron Microscopy(SEM),demonstrating a critical correlation between laser power and pore *** laser power led to increased pore coverage,whereas a denser structure was observed at higher laser *** laser power influence on porosity was further confirmed via Optical Microscopy(OM)conducted on both top and cross-sectional surfaces of the *** increase in laser power resulted in a decrease in pore coverage and pore size,potentially leading to a denser printed part of Mg alloy.X-ray Computed Tomography(XCT)augmented these findings by providing a 3D volumetric representation of the sample internal structure,revealing an inverse relationship between laser power and overall pore *** laser power appeared to favour the formation of interconnected pores,while a reduction in interconnected pores and an increase in isolated pores were observed at higher *** interplay between melt pool size,vapour plume effects,and laser power was found to significantly influence the resulting porosity,indicating a need for effective management of these factors to optimise the SLM process of Mg alloys.

关键词： Selective laser melting(SLM) Magnesium(Mg)alloys Biodegradable implants porosity In-situ monitoring

Cellular zinc metabolism and zinc signaling:from biological functions to diseases and therapeutic targets

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Signal Transduction and Targeted Therapy 2024年第2期9卷 401-441页

作者： Bonan Chen peiyao Yu wai Nok Chan Fuda Xie Yigan Zhang Li Liang kam Tong Leung kwok wai Lo Jun Yu Gary M.k.Tse Wei kang ka Fai To Department of Anatomical and Cellular pathology State Key Laboratory of Translational OncologyPrince of Wales HospitalThe Chinese University of Hong KongHong KongChina State key Laboratory of Digestive Disease Institute of Digestive DiseaseThe Chinese University of Hong KongHong KongChina CUHk-Shenzhen Research Institute The Chinese University of Hong KongShenzhenChina Department of pathology Nanfang Hospital and Basic Medical CollegeSouthern Medical UniversityGuangdong Province Key Laboratory of Molecular Tumor PathologyGuangzhouChina Institute of Biomedical Research Taihe HospitalHubei University of MedicineShiyanChina Department of pediatrics The Chinese University of Hong KongHong KongChina Department of Medicine and Therapeutics The Chinese University of Hong KongHong KongChina

Zinc metabolism at the cellular level is critical for many biological processes in the body.A key observation is the disruption of cellular homeostasis,often coinciding with disease *** an essential factor in maintaining cellular equilibrium,cellular zinc has been increasingly spotlighted in the context of disease *** research suggests zinc’s involvement in promoting malignancy and invasion in cancer cells,despite its low tissue *** has led to a growing body of literature investigating zinc’s cellular metabolism,particularly the functions of zinc transporters and storage mechanisms during cancer *** transportation is under the control of two major transporter families:SLC30(ZnT)for the excretion of zinc and SLC39(ZIp)for the zinc ***,the storage of this essential element is predominantly mediated by metallothioneins(MTs).This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression,with a special focus on *** also compile a summary of clinical trials involving zinc *** the main localization of zinc transporters at the cell membrane,the potential for targeted therapies,including small molecules and monoclonal antibodies,offers promising avenues for future exploration.

关键词： metabolism invasion involvement

Three-dimensional numerical analysis of plant-soil hydraulic interactions on pore water pressure of vegetated slope under different rainfall patterns

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3696-3706页

作者： Haowen Guo Charles Wang wai Ng Qi Zhang Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina

Understanding the pore water pressure distribution in unsaturated soil is crucial in predicting shallow landslides triggered by rainfall,mainly when dealing with different temporal patterns of rainfall ***,the hydrological response of vegetated slopes,especially three-dimensional(3D)slopes covered with shrubs,under different rainfall patterns remains unclear and requires further *** address this issue,this study adopts a novel 3D numerical model for simulating hydraulic interactions between the root system of the shrub and the surrounding *** series of numerical parametric studies are conducted to investigate the influences of slope inclination,rainfall pattern and rainfall *** rainfall patterns(advanced,bimodal,delayed,and uniform)and two rainfall durations(4-h intense and 168-h mild rainfall)are considered to study the hydrological response of the *** computed results show that 17%higher transpiration-induced suction is found for a steeper slope,which remains even after a short,intense rainfall with a 100-year return *** extreme rainfalls with advanced(pA),bimodal(pB)and uniform(pU)rainfall patterns need to be considered for the short rainfall duration(4 h),while the delayed(pD)and uniform(pU)rainfall patterns are highly recommended for long rainfall durations(168 h).The presence of plants can improve slope stability markedly under extreme rainfall with a short duration(4 h).For the long duration(168 h),the benefit of the plant in preserving pore-water pressure(pWp)and slope stability may not be sufficient.

关键词： Root-soil interactions Rainfall patterns Slope stability Three-dimensional(3D)

Defined hydrogels for spinal cord organoids:challenges and potential applications

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Neural Regeneration Research 2024年第11期19卷 2329-2330页

作者： wai Hon Chooi Yuewen Wu Shi-Yan Ng Institute of Molecular and Cell Biology(IMCB) Agency for ScienceTechnology and Research(A*STAR)SingaporeSingapore Department of physiology Yong Loo Lin School of MedicineNational University of Singapore(NUS)SingaporeSingapore

Organoids of the central nervous system,primarily derived from pluripotent stem cells or neural stem cells,are three-dimensional tissue cultures with self-organizing *** exposed to the right combinations of signals,they differentiate into a 3D tissue consisting of complex cytoarchitecture and native cell types,including various neuron subtypes and glial *** features closely mimic native tissues,making them invaluable for developmental studies and disease *** recent years,spinal cord organoids(SCOs)have been developed to investigate spinal cord development,injuries,and various neurological *** an integral part of the central nervous system,SCOs play a vital role and serve as a site for studying both neurodevelopment and neurodegenerative diseases.

关键词： properties injuries primarily

Detection of Turbulence Anomalies Using a Symbolic Classifier Algorithm in Airborne Quick Access Record(QAR)Data Analysis

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Advances in Atmospheric Sciences 2024年第7期41卷 1438-1449页

作者： Zibo ZHUANG kunyun LIN Hongying ZHANG pak-wai CHAN Flight Academy Civil Aviation University of ChinaTianjin 300300China School of Electronic Information and Automation Civil Aviation University of ChinaTianjin 300300China Aviation Weather Services Hong Kong ObservatoryHong KongChina

As the risks associated with air turbulence are intensified by climate change and the growth of the aviation industry,it has become imperative to monitor and mitigate these threats to ensure civil aviation *** eddy dissipation rate(EDR)has been established as the standard metric for quantifying turbulence in civil *** study aims to explore a universally applicable symbolic classification approach based on genetic programming to detect turbulence anomalies using quick access recorder(QAR)*** detection of atmospheric turbulence is approached as an anomaly detection *** evaluations demonstrate that this approach performs on par with direct EDR calculation methods in identifying turbulence ***,comparisons with alternative machine learning techniques indicate that the proposed technique is the optimal methodology currently *** summary,the use of symbolic classification via genetic programming enables accurate turbulence detection from QAR data,comparable to that with established EDR approaches and surpassing that achieved with machine learning *** finding highlights the potential of integrating symbolic classifiers into turbulence monitoring systems to enhance civil aviation safety amidst rising environmental and operational hazards.

关键词： turbulence detection symbolic classifier quick access recorder data

A study of the effect of local scour on the flow field near the spur dike

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 98-105页

作者： Yu-Tian Li Jie-Min Zhan Wing-Hong Onyx wai Department of Industrial Design School of Industrial Design and Ceramic ArtFoshan UniversityFoshan 528000China Department of Applied Mechanics and Engineering Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

The flow field near a spur dike such as down flow and horseshoe vortex system(HVS)are susceptible to the topographic changes in the local scouring process,resulting in variation of the sediment transport with *** this study,large eddy simulations with fixed-bed at different scouring stages were conducted to investigate the changes in flow *** results imply that the bed deformation leads to an increase in flow rate per unit area,which represent the capability of sediment transportation by water,in the scour ***,the intensity of turbulent kinetic energy and bimodal motion near the sand bed induced by the HVS were also ***,the peak moments between the two sediment transport mechanisms were ***,understanding the complex feedback mechanism between topography and flow field is essential for the local scour problem.

关键词： Spur dike Local scour Large eddy simulation Down flow Horseshoe vortex system