双高斯波束对手性粒子的辐射力特性

Radiation force characteristics on chiral particles by dual Gaussian beams

提出了一种研究双高斯波束对手性粒子辐射力的方法。假设光波束以任意方向传播,利用坐标旋转定理在粒子坐标系中以球矢量波函数对双高斯波束进行扩展;通过对入射场的叠加,得到双高斯波束总入射场的展开系数;根据广义洛伦兹-米氏理论和麦克斯韦应力张量理论,推导出作用在手性粒子上辐射力的解析表达式。仿真结果表明:当手性粒子退化为各向同性介质球时,辐射力仿真结果与相关经典文献吻合;双高斯波束的束腰宽度变化对其捕获手性粒子的能力影响不大;随着双高斯波束偏振角的减小,双高斯波对手性粒子的捕获能力会增强;线性偏振的双高斯波束照射具有大手性参数的球体时,产生的辐射力将变小,使得捕获变得更加困难;右旋圆极化双高斯波束对手性参数为负的手性粒子捕获的概率更大;所提出的双高斯波束较单高斯波束更容易捕获大尺寸的手性粒子;双高斯波束的稳定俘获性能对手性粒子的手性参数十分敏感;采用合适的圆偏振态的双高斯波束可能更容易实现对手性粒子的轴向捕获。

A method for investigating the radiation force on chiral particles by dual Gaussian beams is proposed.Assuming that the beams propagate in arbitrary directions,the coordinate rotation theorem is employed to expand the beams into spherical vector wave functions in the particle’s coordinate system.By superimposing the vector fields,the expansion coefficients of the total incident field are obtained.Analytical expressions for the radiation force on a chiral sphere are derived based on the generalized Lorentz Mie theory and the Maxwell stress tensor theory.Simulation results show that:When the degenerate chiral sphere is replaced by an isotropic medium sphere,the simulation results of the radiation force agree with the relevant classical literature.The capture ability of dual Gaussian beams irradiating chiral particles is not significantly affected by changes in the waist width of the beams.As the polarization angle of the dual Gaussian beam decreases,the capturing ability of the beam towards the particles increases.When linearly polarized Gaussian standing waves irradiate spheres with a large chiral parameter,the resulting radiation force decreases,making capture more difficult.The probability of capturing chiral medium spheres with a negative chiral parameter by right-handed circularly polarized Gaussian standing waves is greater.The proposed dual Gaussian standing beam trap is easier to capture or confine large sized chiral spherical particles compared to a single Gaussian beam.The stable capture of the standing wave trap is very sensitive to the chiral parameter,and using an appropriate circularly polarized state standing wave may facilitate axial capture of chiral spheres more easily.