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Controllable optical emission wavelength in all-inorganic halide perovskite alloy microplates grown by two-step chemical vapor deposition

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Nano Research 2020年第11期13卷 2939-2949页

作者： Mohammad K.hossain Pengfei Guo Wayesh Qarony yuen h.tsang Chaoping Liu Sai W.tsang Johnny C.ho Kin M.Yu Department of Physics City University of Hong KongKowloonHong Kong SARChina Department of Physics Comilla UniversityKotbariCumilla3506Bangladesh Department of Materials Science and Engineering City University of Hong KongKowloonHong Kong SARChina Department of Applied Physics The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina College of Physics and Optoelectronics Taiyuan University of TechnologyTaiyuan030024China Research Center for Advanced Optics and Photoelectronics Department of PhysicsCollege of ScienceShantou UniversityShantou515063China Key Laboratory of Intelligent Manufacturing Technology of MOE Shantou UniversityShantou515063China

All-inorganic halide perovskites(IhP),CsPbX_(3)(X=Cl,Br,I)exhibiting efficient optical emissions within the spectral range of 410 to 730 nm are potential candidates for many optoelectronic *** alloying of these IhPs is expected to achieve tunable emission wavelength covering the entire visible ***,we developed a two-step chemical vapor deposition(CVD)process for growing quaternary IhP CsPbX_(3)(X=Cl/Br and Br/I)*** exploiting the fast diffusion of halide anions in IhPs,the alloy composition can be precisely controlled by the growth time of the respective layers once the growth of the individual ternary IhP is *** complexities in the multi-parameter optimization in the conventional CVD growth of quaternary alloys can be *** this process,we synthesized single crystalline,homogeneous and thermally stable CsPbCl3_((1−X))Br_(3x)and CsPbBr3_((1−X))I_(3x)perovskites alloy microplates and demonstrated continuously tunable emission covering the spectrum from 428 to 715 nm by varying the halide compositions in the *** alloy microplates also exhibit room temperature amplified spontaneous emissions(ASE)along with strong photonic discharges from the microplate’s edges and hence are potentially useful as a gain medium as well as optical cavities for emissions with wavelengths covering the visible spectrum.

关键词： chemical vapor deposition inorganic perovskites quaternary alloys emission spectrum amplified spontaneous emissions(ASE)

Graphene-Oxide-Based Q-Switched Fiber Laser with Stable Five-Wavelength Operation

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Chinese Physics Letters 2012年第11期29卷 81-84页

作者： ZhAO Jun-Qing WANG Yong-Gang YAN Pei-Guang RUAN Shuang-Chen ChENG Jian-Qun DU Ge-Guo YU Yong-Qin ZhANG Ge-Lin WEI hui-Feng LUO Jie yuen h.tsang Shenzhen Key Laboratory of Laser Engineering College of Electronic Science and TechnologyShenzhen UniversityShenzhen 518060 Department of Applied Physics Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Optical Fiber and Cable Manufacture Technology Yangtze Optical Fiber and Cable Company Ltd.R&D CenterWuhan 430073

We demonstrate an erbium-doped ring-cavity fiber laser Q-switched by a graphene oxide-based saturable absorber(GOSA).The GOSA was fabricated by vertically evaporating GO-polyvinylalcohol(GO/PVA)composite dispersion,and has a good performance under room *** a specially fabricated fiber Bragg grating(FBG),stable five-wavelength lasing is realized and stabilized at different pump powers under any *** the pump power increases from 78.4 mW to 379.3 mW,the output power ranging from 1.9 mW to 16.6 mW could be obtained,with pulse duration from 6.8μs to 2.72μs,single pulse energy from 123.73 nJ to 229.74 nJ,and pulse repetition rate from 15.36 khz to 72.25 *** the best of our knowledge,it is the first simultaneous realization of five-wavelength operation and pulse output in a GO Q-switched all fiber laser system.

关键词： pump fiber switched

high-average-power, high-repetition-rate tunable terahertz difference frequency generation with GaSe crystal pumped by 2 μm dual-wavelength intracavity KTP optical parametric oscillator

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Photonics Research 2017年第2期5卷 82-87页

作者： DEXIAN YAN YUYE WANG DEGANG XU PENGXIANG LIU ChAO YAN JIA ShI hONGXIANG LIU YIXIN hE LONGhUANG TANG JIANChEN FENG JIANQIN GUO WEI ShI KAI ZhONG yuen h.tsang JIANQUAN YAO School of Precision Instrument and Opto-electronics Engineering Tianjin University Key Laboratory of Opto-electronics Information Technology Tianjin University Ministry of Education Institute of Neurosurgery Southwest Hospital Third Military Medical University Department of Applied Physics the Hong Kong Polytechnic University

We have demonstrated a high-average-power,high-repetition-rate optical terahertz(Thz)source based on difference frequency generation(DFG)in the GaSe crystal by using a near-degenerate 2μm intracavity KTP optical parametric oscillator as the pump *** power of the 2μm dual-wavelength laser was up to 12.33 W with continuous tuning ranges of 1988.0–2196.2 nm/2278.4–2065.6 nm for two *** GaSe cystal lengths have been experimentally investigated for the DFG Thz source in order to optimize the Thz output power,which was in good agreement with the theoretical *** on an 8 mm long GaSe crystal,the Thz wave was continuously tuned from 0.21 to 3 *** maximum Thz average power of 1.66μW was obtained at repetition rate of 10 khz under 1.48 *** single pulse energy amounted to 166 pJ and the conversion efficiency from 2 μm laser to Thz output was 1.68×10^(-6).The signal-to-noise ratio of the detected Thz voltage was 23 *** acceptance angle of DFG in the GaSe crystal was measured to be 0.16°.

关键词： GaSe Thz KTP high-average-power m dual-wavelength intracavity KTP optical parametric oscillator rate

Computational design of promising 2D electrode materials for Li-ion and Li–S battery applications

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Materials Reports(Energy) 2023年第3期3卷 1-23页

作者： Ke Fan yuen hong tsang haitao huang Department of Applied Physics and Research Institute for Smart Energy The Hong Kong Polytechnic UniversityHong KongChina

Lithium-ion batteries(LIBs)and lithium-sulfur(Li–S)batteries are two types of energy storage systems with significance in both scientific research and ***,the rational design of electrode materials for overcoming the bottlenecks of LIBs and Li–S batteries(such as low diffusion rates in LIBs and low sulfur utilization in Li–S batteries)remain the greatest challenge,while two-dimensional(2D)electrodes materials provide a solution because of their unique structural and electrochemical *** this article,from the perspective of ab-initio simulations,we review the design of 2D electrode materials for LIBs and Li–S *** first propose the theoretical design principles for 2D electrodes,including stability,electronic properties,capacity,and ion diffusion ***,classified examples of promising 2D electrodes designed by theoretical simulations are given,covering graphene,phosphorene,MXene,transition metal sulfides,and so ***,common challenges and a future perspective are *** review paves the way for rational design of 2D electrode materials for LIBs and Li–S battery applications and may provide a guide for future experiments.

关键词： Lithium-ion batteries Lithium-sulfur batteries 2D electrode materials Computational design

Perovskite/Silicon Tandem Solar Cells: From Detailed Balance Limit Calculations to Photon Management

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Nano-Micro Letters 2019年第4期11卷 49-72页

作者： Mohammad I.hossain Wayesh Qarony Sainan Ma Longhui Zeng Dietmar Knipp yuen hong tsang Department of Applied Physics The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China Geballe Laboratory for Advanced Materials Department of Materials Science and EngineeringStanford UniversityStanfordCA 94305USA

Energy conversion efficiency losses and limits of perovskite/silicon tandem solar cells are investigated by detailed balance calculations and photon *** extended Shockley-Queisser model is used to identify fundamental loss mechanisms and link the losses to the optics of solar *** management is used to minimize losses and maximize the energy conversion *** influence of photon management on the solar cell parameters of a perovskite single-junction solar cell and a perovskite/silicon solar cell is discussed in greater *** optimized solar cell design of a perovskite/silicon tandem solar cell is presented,which allows for the realization of solar cells with energy conversion efficiencies exceeding 32%.

关键词： Perovskite solar cell Tandem solar cell Thermodynamic Photon management Detailed balance limit

Passively Q-switched and femtosecond modelocked erbium-doped fiber laser based on a 2D palladium disulfide(PdS2) saturable absorber

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Photonics Research 2020年第4期8卷 511-518页

作者： PING KWONG ChENG ChUN YIN TANG XIN YU WANG LONG-hUI ZENG yuen hONG tsang Department of Applied Physics and Materials Research Center The Hong Kong Polytechnic UniversityHung HornKowloonHong KongChina

Stable Q-switched and mode-locked erbium-doped fiber lasers(EDFLs)are first demonstrated by using the novel layered palladium disulfide(PdS2),a new member of group 10 transition metal dichalcogenides(TMDs)-based saturable absorbers(SAs).Self-started Q-switched operation at 1567 nm was achieved with a threshold pump power of 50.6 *** modulation ranges of pulse duration and repetition rate were characterized as 12.6-4.5μs and 17.2-26.0 khz,***,a mode-locked EDFL was also obtained with a pump power threshold of 106.4 *** achieved pulse duration is 803 fs,corresponding to a center wavelength of 1565.8 nm and4.48 nm 3 dB *** the best of our knowledge,the achieved pulse duration of the mode-locked EDFL in this work is the narrowest compared with all other group 10 TMD SA-based lasers.

关键词： Passively Q-switched femtosecond modelocked erbium-doped fiber laser a 2D palladium disulfide

Eyes and stroke:the visual aspects of cerebrovascular disease

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Stroke & Vascular Neurology 2017年第4期2卷 211-221页

作者： John h Pula Carlen A yuen Department of Neurology NorthShore University HealthSystemChicagoIllinoisUSA Department of Neurology University of ChicagoChicagoIllinoisUSA

A large portion of the central nervous system is dedicated to vision and therefore strokes have a high likelihood of involving vision in some *** loss can be the most disabling residual effect after a cerebral *** vision problems can likewise be a harbinger of stroke and prompt evaluation after recognition of visual symptoms can prevent future vascular *** this review,we discuss the visual aspects of ***,anatomy and the vascular supply of the visual system are ***,the different stroke syndromes which involve vision are ***,topics involving the assessment,prognosis,treatment and therapeutic intervention of vision-specific stroke topics are reviewed.

关键词： anatomy ed. visual

highly sensitive solar-blind deep ultraviolet photodetector based on graphene/PtSe_(2)/β-Ga_(2)O_(3)2D/3D Schottky junction with ultrafast speed

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Nano Research 2021年第6期14卷 1973-1979页

作者： Di Wu Zhihui Zhao Wei Lu Lukas Rogée Longhui Zeng Pei Lin Zhifeng Shi Yongtao Tian Xinjian Li yuen hong tsang School of Physics and Microelectronics and Key Laboratory of Material PhysicsZhengzhou UniversityZhengzhou450052China Department of Applied Physics The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

There is an emerging need for high-sensitivity solar-blind deep ultraviolet(DUV)photodetectors with an ultra-fast response *** nanoscale devices based on Ga_(2)O_(3)nanostructures have been developed,their practical applications are greatly limited by their slow response speed as well as low specific ***,the successful fabrication of two-/three-dimensional(2D/3D)graphene(Gr)/PtSe2/β-Ga_(2)O_(3)Schottky junction devices for high-sensitivity solar-blind DUV photodetectors is *** from the high-quality 2D/3D Schottky junction,the vertically stacked structure,and the superior-quality transparent graphene electrode for effective carrier collection,the photodetector is highly sensitive to DUV light illumination and achieves a high responsivity of 76.2 mA/W,a large on/off current ratio of~105,along with an ultra-high ultraviolet(UV)/visible rejection ratio of 1.8×*** importantly,it has an ultra-fast response time of 12µs and a remarkable specific detectivity of~1013 ***,an excellent DUV imaging capability has been identified based on the Gr/PtSe2/β-Ga_(2)O_(3)Schottky junction photodetector,demonstrating its great potential application in DUV imaging systems.

关键词： platinum diselenide β-Ga_(2)O_(3) solar-blind photodetectors deep ultraviolet imaging

Correlations of baryon and charge stopping in heavy ion collisions

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Chinese Physics C 2024年第4期48卷 89-94页

作者：吕文棣李洋李子阳马荣荣唐泽波 Prithwish Tribedy Chun yuen tsang 许长补查王妹 State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China Physics Department Brookhaven National LaboratoryUptonNY 11973USA Department of Physics Kent State UniversityKentOH 44242USA

Baryon numbers are theorized to be carried by valence quarks in the standard QCD picture of the baryon *** theory proposed an alternative baryon number carrier,a non-perturbative Y-shaped configuration of the gluon field,called the baryon junction in the ***,neither of these theories has been verified ***,searching for the baryon junction by investigating the correlation of net-charge and net-baryon yields at midrapidity in heavy-ion collisions has been *** paper presents studies of such correlations in collisions of various heavy ions from oxygen to uranium with the UrQMD Monte Carlo *** UrQMD model implements valence quark transport as the primary means of charge and baryon stopping at *** studies are also conducted for isobaric ^(96)_(40)Zr+^(96)_(40)Zr and ^(96)_(44)Ru+^(96)_(44)Ru *** found a universal trend of charge stopping with respect to baryon stopping and discovered that the charge stopping is always greater than the baryon *** study provides a model baseline in valence quark transport for what is expected in net-charge and net-baryon yields at the midrapidity of relativistic heavy-ion collisions.

关键词： baryon junction baryon number carrier baryon stopping relativistic heavy ion collisions