高阶径向拉盖尔-高斯型飞秒脉冲激光场中级联三能级原子所受光学偶极力  

Optical Dipole Forces of Laguerre-Gaussian Femtosecond Laser Pulses with High Radial Modes on Cascade Three-Level Atoms

作　　者：管文慧 王翦 袁烁 Abdul Gheyas Abdul Rashid 郭芬芬 刘纪彩 Guan Wenhui;Wang Jian;Yuan Shuo;Abdul Gheyas Abdul Rashid;Guo Fenfen;Liu Jicai(School of Mathematics and Physics,North China Electric Power University,Beijing 102206,China;School of Nuclear Science and Engineering,North China Electric Power University,Beijing 102206,China;Hebei Key Laboratory of Physics and Energy Technology,Baoding 071000,Hebei,China)

机构地区：[1]华北电力大学数理学院,北京102206 [2]华北电力大学核科学与工程学院,北京102206 [3]河北省物理学与能源技术重点实验室,河北保定071000

出　　处：《光学学报》2023年第19期271-279,共9页Acta Optica Sinica

基　　金：国家自然科学基金(11974108,12211530044)。

摘　　要：采用量子化的密度矩阵理论,对级联三能级原子束在具有不同径向阶次的柱对称拉盖尔-高斯(LG)型飞秒脉冲激光场中所受的光学势和光学偶极力(ODF)进行研究。结果表明:在飞秒脉冲激光场中,ODF的大小以两倍于激光载波频率的频率作周期性振荡;在n阶径向模式的LG型激光场作用下,径向偶极力具有2n个节线圆,在节线圆的两侧偶极力方向相反,因此原子将发生分束,从而被俘获到不同的光势阱内;在负/正激光场失谐条件下,形成n+1个光学势阱/垒数;在相同光场峰值强度下,随着光束径向阶次n的增大,主势阱/垒的深度保持不变,但主势阱/垒的空间范围变窄,光学势的径向梯度增加,从而使得ODF增大。因此,采用高阶LG光束可以将粒子束缚在更窄的光学势内,更有利于粒子的精准操控和俘获。Objective When atoms are exposed to a non-uniform laser field,there will be gradient potential due to the electric dipole interactions between the light field and the atoms,and therefore atoms will be subjected to the action of optical dipole forces.With the recent development of ultra-short laser technology and light manipulation techniques,new types of light fields with complex spatial structures are possible to be constructed.Meanwhile,the application of these new laser fields in optical tweezers to achieve special and accurate control of micro-particles becomes a hotspot in light-matter interactions.Compared with the fundamental transverse mode Gaussian beams,these laser fields,such as hollow Gaussian beam,Laguerre-Gaussian beam,Bessel-Gaussian beam,and Airy beam,have more complex field structures and special optical characteristics.Additionally,they can provide extensive controllable degrees of freedom and more atomic beam guidance pathways for laser manipulation.Our paper studies the electric dipole interactions between the femtosecond Laguerre-Gaussian laser pulses of high radial modes and the three-level atomic systems.The spatiotemporal distribution characteristics of optical potential traps and optical dipole forces exerted by different radial modes of the femtosecond Laguerre-Gaussian laser beams are analyzed.We also reveal the advantages of Laguerre-Gaussian laser beams with high radial modes in atom trapping and manipulation.This theoretical study is expected to give insight into the optical manipulation of micro-particles with structured optical laser fields and provide guidance for possible experimental studies.Methods The semi-classical theory is employed to study the interactions of optical dipole forces between the femtosecond Laguerre-Gaussian laser pulses with high radial modes and the cascade three-level atoms.The laser field is treated with the classical Maxwell's theory and the atoms are treated with the quantum mechanical density matrix theory.Based on the density matrix theory,the optical

关 键 词：量子光学 光学偶极力 光学势 拉盖尔-高斯激光脉冲 级联三能级原子体系 密度矩阵方程 

分 类 号：O437[机械工程—光学工程]