检索结果-南通市图书馆

Yield enhancement of elliptical high harmonics driven by bicircular laser pulses

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第11期31卷 358-363页

作者：张晓凡祝晓松 Hubei Key laboratory of optical Information and Pattern Recognition Wuhan Institute of TechnologyWuhan 430205China Wuhan National laboratory for Optoelectronics and School of Physics Huazhong University of Science and TechnologyWuhan 430074China

We theoretically investigate the yield enhancement of elliptical high harmonics in the interaction of molecules with bicircular laser pulses by solving the time-dependent Schrodinger *** is shown that by adjusting the relative intensity ratio of the two bicircular field components in specific ranges the yield of the molecular high harmonics for the plateau and cutoff regions can be respectively *** analyze this enhancement phenomenon,we calculate the weights of the electron classical ***,we also study the ellipticity distribution of harmonics for different intensity *** find that these enhanced harmonics are elliptically polarized,which we mainly attribute to the recombination dipole moment of the major weighted *** enhanced elliptical extreme ultraviolet and soft x-ray radiations may serve as essential tools for exploring the ultrafast dynamics in magnetic materials and chiral media.

关键词： high harmonics extreme ultraviolet and soft x-ray bicircular laser pulses

Plasmonic vortex beam emitter

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2023年第10期11卷 1723-1732页

作者： ZI-WEN ZHANG YU-LU LEI JUAN-FENG ZHU CHAO-HAI DU Center for Carbon-based Electronics School of ElectronicsPeking UniversityBeijing 100871China State Key laboratory of Advanced optical Communication Systems and Networks School of ElectronicsPeking UniversityBeijing 100871China Science Mathematicsand Technology(SMT)Singapore University of Technology and DesignSingapore 487372Singapore

Terahertz vortices prompt numerous advanced applications spanning classical and quantum communications,sensing, and chirality-based detection, owing to the inherent physical properties of terahertz waves and orbital angular momentum(OAM). Nonetheless, existing methodologies for generating terahertz vortices face challenges such as unalterable topological charges and intricate feed networks. To address these limitations, we propose a novel approach to generate multi-mode and tunable vortex beams based on chiral plasmons. Through eigenmode analysis, the uniform helical gratings are demonstrated to support chiral plasmons carrying OAM. By leveraging their vortex characteristics and introducing modulation into the periodic system, these chiral plasmons are alternatively diffracted into high-purity vortex radiations according to the Bragg law. To validate the theory, the vortex beam emitter is fabricated and measured in the microwave regime based on the modulated scheme. Experimental results confirm the emission of vortex beams with desirable phase distributions and radiation patterns. Our findings highlight the potential of chiral plasmons as seeds for tunable and compact vortex radiation, offering promising applications in tunable vortex sources.

关键词： emitter tunable vortex

Scatterings from surface plasmons to propagating waves at plasmonic discontinuities

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2019年第12期64卷 802-807页

作者： Fuxin Guan Shulin Sun Shiyi Xiao Qiong He Lei Zhou Key laboratory of Micro and Nano Photonic Structures (Ministry of Education) and State Key laboratory of Surface Physics Fudan UniversityShanghai 200433China Shanghai Engineering Research Center of Ultra-Precision optical Manufacturing and Department of optical Science and Engineering Fudan UniversityShanghai 200433China Key laboratory of Specialty Fiber Optics and optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced CommunicationShanghai Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China

Surface plasmon polaritons (SPPs) and their low-frequency counterpart spoof SPPs have attracted intensive interests in sciences [1,2], due to their unprecedented capabilities to confine electromagnetic (EM) fields at deep-subwavelength scale, leading to many applications such as super-resolution imaging [3], plasmonic lasers [4], surfaced-enhanced Raman effect [5], plasmonic waveguides [6,7] or circuits [8], etc. In practice, scatterings of SPPs to propagating waves (PWs) are inevitable as SPPs encounter discontinuities (say, interfaces between two different plasmonic systems). Such scatterings can lead to undesired radiation losses which should be avoided, especially in those applications employing SPPs as information carriers (say, plasmonic waveguides and nano-circuits [6–8]). Meanwhile, SPP-PW scatterings can also be utilized to achieve certain desired functionalities. For example, one can purposely place a set of carefully designed scatters on a plasmonic surface to scatter SPPs, generating fascinating effects such as holograms, focusing, or even directional radiations [9,10]. However, theoretical understandings on the inherent physics governing SPP-PW scatterings are far from satisfactory. Without a simple picture on such processes, people usually have to rely on full-wave simulations to optimize the devices to either suppress or utilize the SPP-PW scatterings. Although several theoretical approaches were proposed to study the SPP transmission/ reflection behaviors at certain plasmonic interfaces [11,12], the SPP-PW scatterings are usually overlooked. Moreover, since PWs have infinite channels to transport in free space, it is difficult to derive an analytical formula to describe such SPP-PW processes.

关键词： Surface plasmon polaritons(SPPs) electromagnetic(EM) propagating waves(PWs)

Ab initio Calculations of Electron-Impact Excitation Cross Sections for N_2 Molecule

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2014年第2期16卷 104-109页

作者：信裕丁洪斌 School of Physics and optical Engineering Key Laboratory of Materials Modification byLaserIon and Electron BeamsMinistry of EducationDalian University of Technology

One of the great difficulties in understanding nitrogen plasma elementary processes is the lack of an available database of the cross-sections of electron-impact excitations and radiations. Ab initio calculations of vibrational excitation cross sections for electron collisions with nitrogen molecules in low-lying states using similarity function approach, such as a-a＇, a-w, B-B＇ and B-W transition systems, are reported here for the first time. In the meantime, the average excitation energies of neighboring levels of these systems have been calculated. In order to obtain the cross sections, accurate spectroscopic constants and transition dipole moments have been investigated. Potential energy curves and other electronic transition dipole moments for the low-lying states of N2 have been re-evaluated using complete active space self-consistent field （CASSCF） approach with aug-cc-pVqZ basis set. The calculated cross-sections could provide a database for studying the elementary processes and the properties in N2 plasma.

关键词： N2 potential energy curves transition dipole moments electron-impact exci- tation cross sections

Bound states in the continuum based on the total internal reflection of Bloch waves

在线全文

学校读者我要写书评

暂无评论

National Science Review 2023年第1期10卷 178-186页

作者： Peng Hu Chongwu Xie Qianju Song Ang Chen Hong Xiang Dezhuan Han Jian Zi College of Physics Chongqing University State Key laboratory of Surface Physics Key Laboratory of Microand Nano-Photonic Structures (Ministry of Education) and Department of Physics Fudan University Chongqing Key laboratory for Strongly Coupled Physics

A photonic-crystal slab can support bound states in the continuum(BICs) that have infinite lifetimes but are embedded into the continuous spectrum of optical modes in free *** formation of BICs re quires a total internal reflection(TIR) condition at both interfaces between the slab and the free ***,we show that the TIR of Bloch waves can be directly obtained based on the generalized Fresnel equations *** each of these Bloch waves picks up a phase with integer multiples of 2π for traveling a round trip,light can be perfectly guided in the slab,namely forming a BIC.A BIC solver with low computational complexity and fast convergence speed is developed,which can also work efficiently at high frequencies beyond the diffraction limit where multiple radiation channels *** examples of multi-channel BICs are shown and their topological nature in momentum space is also *** can be attributed to the coincidence of the topological charges of far-field radiations from different radiation *** concept of the generalized TIR and the TIR-based BIC solver developed offer highly effective approaches for explorations of BICs that could have many potential applications in guided-wave optics and enhanced light-matter interactions.

关键词： bound states in the continuum total internal reflection Bloch waves generalized Fresnel equations topological charges

Nonlinear radiation response of n-doped indium antimonide and indium arsenide in intense terahertz field

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第10期25卷 24-29页

作者：龚姣丽刘劲松褚政杨振刚王可嘉姚建铨 Wuhan National laboratory for Optoelectronics School of Optical and Electronic InformationHuazhong University of Science and Technology School of Science Hubei University of Technology Hubei Collaborative Innovation Center for High-efficient Utilization of Solar Energy Hubei University of Technology

The nonlinear radiation responses of two different n-doped bulk semiconductors: indium antimonide(In Sb) and indium arsenide(In As) in an intense terahertz(THz) field are studied by using the method of ensemble Monte Carlo(EMC)at room temperature. The results show that the radiations of two materials generate about 2-THz periodic regular spectrum distributions under a high field of 100 k V/cm at 1-THz center frequency. The center frequencies are enhanced to about 7 THz in In Sb, and only 5 THz in In As, respectively. The electron valley occupancy and the percentage of new electrons excited by impact ionization are also calculated. We find that the band nonparabolicity and impact ionization promote the generation of nonlinear high frequency radiation, while intervalley scattering has the opposite effect. Moreover, the impact ionization dominates in In Sb, while impact ionization and intervalley scattering work together in In As. These characteristics have potential applications in up-convension of THz wave and THz nonlinear frequency multiplication field.

关键词： ensemble Monte Carlo nonparabolicity impact ionization intervalley scattering

X-ray scintillation in lead-free double perovskite crystals

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2018年第12期61卷 1581-1586页

作者： Qingsong Hu Zhenzhou Deng Manchen Hu Anjiang Zhao Yaqi Zhang Zhifang Tan Guangda Niu Haodi Wu Jiang Tang Wuhan National laboratory for Optoelectronics(WNLO) Huazhong University of Science and Technology (HUST) School of Information Engineering Nanchang University School of optical and Electronic Information Huazhong University of Science and Technology (HUST) College of Life Science and Technology Huazhong University of Science and Technology (HUST) College of Physics Huazhong University of Science and Technology (HUST)

Metal halide perovskites have shown great performance for various applications,including solar cells,light emitting diodes,and radiation detectors,but they still suffer from the toxicity of lead and *** we report the use of lanthanide series as trivalent metals to obtain low toxicity and highly stable double perovskites(Cs_2NaLnCl_6,Ln=Tb or Eu)with high scintillation light *** crystals exhibit typical f-f transitions of lanthanide cations,while Cs_2NaTbCl_6exhibits strong green photoluminescence,and Cs_2NaEuCl_6exhibits red *** X-ray radiations,the light yield of Cs_2NaTbCl_6reaches46600 photons MeV^(-1),much higher than that of the commercially used(Lu,Y)_2SiO_5:Ce^(3+)crystals(LYSO,28500 photons MeV^(-1)),and previously reported lead-based perovskites(14000 photons MeV^(-1)).As a new member of lead-free perovskites,lanthanide-based double perovskites open up a new route toward radiation detections and potential medical imaging.

关键词： low toxic scintillation light yield lanthanide double perovskites

Linewidth narrowing in free-space-running diamond Brillouin lasers

在线全文

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2023年第4期11卷 25-32页

作者： Duo Jin Zhenxu Bai Zhongan Zhao Yifu Chen Wenqiang Fan Yulei Wang Richard P.Mildren Zhiwei Lü Center for Advanced Laser Technology Hebei University of TechnologyTianjinChina Hebei Key laboratory of Advanced Laser Technology and Equipment TianjinChina MQ Photonics Research Centre Department of Physics and AstronomyMacquarie UniversitySydneyAustralia

This study analyzes the linewidth narrowing characteristics of free-space-running Brillouin lasers and investigates the approaches to achieve linewidth compression and power enhancement *** results show that the Stokes linewidth behavior in a free-space-running Brillouin laser cavity is determined by the phase diffusion of the pump and the technical noise of the ***,a Stokes light output with a power of 22.5 W and a linewidth of 3.2 kHz was obtained at a coupling mirror reflectivity of 96%,which is nearly 2.5 times compressed compared with the linewidth of the pump(7.36 kHz).In addition,the theorical analysis shows that at a pump power of 60Wand a coupling mirror reflectivity of 96%,a Stokes output with a linewidth of 1.6 kHz and up to 80%optical conversion efficiency can be achieved by reducing the insertion loss of the *** study provides a promising technical route to achieve high-power ultra-narrow linewidth special wavelength laser radiations.

关键词： high power narrow linewidth single-frequency laser stimulated Brillouin scattering

Prompt optical emission from gamma-ray bursts with multiple timescale variability of central engine activities

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2014年第4期14卷 411-422页

作者： Si-Yao Xu Zhuo Li Department of Astronomy and Kavli Institute for Astronomy and Astrophysics Peking University Key laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

Complete high-resolution light curves of GRB 080319B observed by Swift present an opportunity for detailed temporal analysis of prompt optical emission. With a two-component distribution of initial Lorentz factors, we simulate the dynamical process of shells being ejected from the central engine in the framework of the in- ternal shock model. The emitted radiations are decomposed into different frequency ranges for a temporal correlation analysis between the light curves in different energy bands. The resulting prompt optical and gamma-ray emissions show similar tempo- ral profiles, with both showing a superposition of a component with slow variability and a component with fast variability, except that the gamma-ray light curve is much more variable than its optical counterpart. The variability in the simulated light curves and the strong correlation with a time lag between the optical and gamma-ray emis- sions are in good agreement with observations of GRB 080319B. Our simulations suggest that the variations seen in the light curves stem from the temporal structure of the shells injected from the central engine of gamma-ray bursts. Future observations with high temporal resolution of prompt optical emission from GRBs, e.g., by UFFO- Pathfinder and SVOM-GWAC, will provide a useful tool for investigating the central engine activity.

关键词： gamma rays: bursts- GRB 080319B