单轴晶体中紧聚焦柱对称矢量涡旋光诱导磁化场特性研究

Study on the Magnetization Field Induced by Tightly Focused Cylindrical Symmetric Vector Vortex Light in a Uniaxial Crystal

本文基于逆法拉第效应,利用矢量衍射理论详细研究了紧聚焦的柱对称矢量涡旋光束在单轴晶体中诱导磁化场的分布.探讨了输入光场矢量特性、单轴晶体磁光常数间的比值、o光和e光折射率差以及各向同性介质-单轴晶体界面位置对磁化场分布的影响.数值模拟发现,单轴晶体磁光常数间的比值愈大、o光和e光折射率差越小以及各向同性介质-单轴晶体界面的位置趋近于透镜焦点,都会使磁化强度得到增强,半高全宽减小.与各向同性介质中的磁化场相比,单轴晶体中磁化场半高全宽更小,磁斑长度更长.这将有利于全光磁存储记录密度的提高以及磁化反转率的提升,并为全光磁记录、原子捕获、光刻等应用提供理论指导和新的调控手段.

Based on the vector diffraction theory and inverse Faraday effect,we detailedly studied the distribution of magnetization fields induced by tightly focused cylindrically polarized vortex beams in a uniaxial crystals. The effects of the vector character of the incident beam,the ratio between the magneto-optical constants of the uniaxial crystal,the value of extraordinary refractive index minus ordinary refractive index,and the location of interface between the isotropic media and the uniaxial crystal are discussed. Based on numerical simulation,it is found that the larger the ratio between the magneto-optical constants of the uniaxial crystal,the smaller the value of extraordinary refractive index minus ordinary refractive index,or the closer the location of interface between the isotropic media and the uniaxial crystal will all increase the maximum intensity of the magnetization field and decrease the full width at half maximum. Importantly,the full width at half maximum of the magnetization field in the uniaxial crystal is smaller than that in an isotropic crystal,and the length of magnetic spot is longer than that in the isotropic crystal. These will be beneficial to the improvement of recording density and the magnetization reversal rate of the all-optical magnetic storage,and will provide theoretical guidance and the new way control for the all-optical magnetic recording,atomic capture,lithography and other applications.