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self-focusing of partially coherent beams based on complex screen and split-step Fourier transform methods

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中国光学快报:英文版 2023年第7期21卷 53-58页

作者：杨方伦张国文张笑琪张艳丽王瑞峰朱健强 School of Physical Sciences University of Science and Technology of ChinaHefei 230026China Key Laboratory of High Power Laser and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China National Laboratory on High Power Laser and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

The self-focusing phenomenon of partially coherent beams(PCBs)was simulated using the complex screen method combined with the split-step Fourier method to solve the nonlinear Schrödinger equation.Considering the propagation of Gaussian Schell-model beams in a nonlinear medium as an example,the suppression effects of intensity,propagation distance,and spatial coherence on small-scale self-focusing were demonstrated.Simulations of overall and small-scale self-focusing using this method were compared with the existing literature to demonstrate the validity of the method.This method can numerically analyze the degree of self-focusing in PCBs and advance the study of their nonlinearity.

关键词： partially coherent beams self-focusing nonlinearity complex screen method Gaussian Schell-model

Correlation-induced self-focusing and self-shaping effect of a partially coherent beam

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High Power Laser Science and Engineering 2016年第2期4卷 90-94页

作者： Yahong Chen Yangjian Cai College of Physics Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and TechnologySoochow University Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China Soochow University

A new specially correlated partially coherent beam named nonuniform multi-Gaussian correlated(NMGC) partially coherent beam is introduced. The correlation functions of such beam in x and y directions are different from each other,i.e., nonuniform correlation function in one direction and multi-Gaussian correlated Schell-model function in the other direction. The propagation properties of an NMGC partially coherent beam in free pace are demonstrated, and we find that the intensity distribution of such beam exhibits self-focusing and self-shifting effect in one direction and self-shaping effect in the other direction on propagation. The correlation-induced self-focusing and self-shaping effect will be useful in some applications, where the high power and shaped laser is required, such as material thermal processing and laser carving.

关键词： correlation function partially coherent beam self-focusing effect self-shaping effect

self-compression of femtosecond pulses in argon with a power close to the self-focusing threshold

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Chinese Physics B 2008年第5期17卷 1826-1832页

作者：陈晓伟曾志男戴君李小芳李儒新徐至展 State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

self-compression of femtosecond pulses in noble gases with an input power close to the self-focusing threshold has been investigated experimentally and theoretically. It is demonstrated that either multiphoton ionization （MPI） or space-time focusing and self-steepening effects can induce pulse shortening, but they predominate at different beam intensities during the propagation. The latter effects play a key role in the final pulse self-compression. By choosing an appropriate focusing parameter, action distance of the space-time focusing and self-steepening effects can be lengthened, which can promote a shock pulse structure with a duration as short as two optical cycles. It is also found that, for our calculation cases in which an input pulse power is close to the self-focusing threshold, either group velocity dispersion （GVD） or multiphoton absorption （MPA） has a negligible influence on pulse characteristics in the propagation process.

关键词： nonlinear propagation self-focusing self-compression

Experimental research of pulsed chirp effect on the small-scale self-focusing

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Science China(Physics,Mechanics & Astronomy) 2008年第11期51卷 1653-1660页

作者： ZHANG LiFu FU XiQuan FENG ZeHu YANG Hua WEN ShuangChun Key Laboratory of Micro/Nano Optoelectronics Devices of Ministry of Education and School of Computer and Communication Hunan UniversityChangsha 410082China

The chirped optical pulses undergoing self-focusing and splitting into multiple filamentation passing through a Kerr medium-carbon disulfide (CS2) are studied experimentally and numerically. At the particular spatial position, modulation growth takes place from the experimental result. The process of modulation growth with different pulsed chirp is analyzed. It is found that with the pulsed chirp in-creasing (equal to the pulse width increasing), modulation growth of chirped opti-cal pulses is delayed and the average input power also increases. The simulation results are in agreement with the experimental results.

关键词： small-scale self-focusing multiple filamentation femtosecond pulse pulsed chirped

self-trapping and self-focusing of Light Beams in Uniaxial Crystals

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Chinese Journal of Lasers 1996年第4期5卷 313-318页

作者： GUO Qi(Institute of Quantum Electronics,South China Normal University,Guangzhou 510631, China) South China Normal Univ Guangzhou China

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关键词： self-trapping self-focusing uniaxial crystal

self-focusing of Quadruple Gaussian Laser Beam in an Inhomogenous Magnetized Plasma with Ponderomotive Non-Linearity:Effect of Linear Absorption

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Communications in Theoretical Physics 2015年第11期64卷 565-570页

作者： Munish Aggarwal Shivani Vij Niti Kant Department of Physics Lyallpur Khalsa College of Engineering Department of Applied Sciences DAV Institute of Engineering & Technology Department of Physics Lovely Professional University

The propagation of quadruple Gaussian laser beam in a plasma characterized by axial inhomogeneity and nonlinearity due to ponderomotive force in the paraxial ray approximation is investigated.An appropriate expression for the nonlinear dielectric constant has been developed in the presence of external magnetic field,with linear absorption and due to saturation effects for arbitrary large intensity.The effects of different types of plasma axial inhomogeneities on self-focusing of laser beam have been studied with the typical laser and plasma parameters.self-focusing of quadruple Gaussian laser beam in the presence of externally applied magnetic field and saturating parameter is found significantly improved in the case of extraordinary mode.Our results reveal that initially converging beam shows oscillatory convergence whereas initially diverging beam shows oscillatory divergence.The beam is more focussed at lower intensity in both cases viz.extraordinary and ordinary mode.

关键词： self-focusing quadruple inhomogeneous magnetized p

Relativistic self-focusing of Hermite-cosine-Gaussian Laser Beam in Collisionless Plasma with Exponential Density Transition

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Communications in Theoretical Physics 2019年第6期71卷 736-740页

作者： Vishal Thakur Manzoor Ahmad Wani Niti Kant Department of Physics Lovely Professional UniversityPhagwara-144411PunjabIndia Govt.Higher Secondary School Waterhail Budgam-191111J&KIndia

This work reveals an exploration of self-focusing of Hermite-cosine-Gaussian laser beam in a collisionless plasma under relativistic nonlinearity. self-focusing along with self-trapping of Hermite-cosine-Gaussian laser beam are analyzed for different values of laser intensity, plasma density, and decentered parameters. Mathematical analysis displays that these parameters play a major role in achieving the stronger and earlier self-focusing. Further, a comparative study between self-focusing of Hermite-cosine-Gaussian laser beam with and without exponential density ramp profile is introduced. Plasma density transition with exponential profile is found to be more effective in order to have stronger self-focusing. The present analysis may lead to very useful applications in the field of efficient harmonic generation, laser driven fusion etc.

关键词： self-focusing collisionless plasma exponential plasma density ramp Hermite-cosine-Gaussian laser beam

Density Transition Based self-focusing of cosh-Gaussian Laser Beam in Plasma with Linear Absorption

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Communications in Theoretical Physics 2015年第7期64卷 103-107页

作者： Niti Kant Manzoor Ahmad Wani Department of Physics Lovely Professional University

Density transition based self-focusing of cosh-Gaussian laser beam in plasma with linear absorption has been studied. The field distribution in the plasma is expressed in terms of beam width parameter, decentered parameter,and linear absorption coefficient. The differential equation for the beam width parameter is solved by following Wentzel–Kramers–Brillouin(WKB) and paraxial approximation through parabolic wave equation approach. The behaviour of beam width parameter with dimensionless distance of propagation is studied at optimum values of plasma density,decentered parameter and with different absorption levels in the medium. The results reveal that these parameters can affect the self-focusing significantly.

关键词： self-focusing cosh-Gaussian beam plasma density ra

Condition of laser pulse width for relativistic self-focusing

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Chinese Science Bulletin 1997年第7期42卷 555-557页

作者： Zeng, GH Yu, W Shen, BF Xu, ZZ Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai China

THE stability propagation and guiding of intense short laser pulse in plasmas is directly associated with a number of laser-plasma interaction phenomena, i.e. the plasma-based accelerator, the generation of radiation source of coherent shortwave length, and some problem of fast ignitor scenario (FIS) in inertial confinement fusion (ICF). It has given rise to a good deal of attention for the stability propagation and enhancing the propagation length of laser pulse.

关键词： relativistic self-focusing intense short laser pulse plasmas.