Theoretical investigation of laser beams with radial polarization

摘要

Laser resonator for generating radially polarized beams is designed with aid of a special wire grid polarizer which is usedas the rear mirror in CO2 lasers. A theoretical model for this resonator with polarization selectivity is established, and thesimulation results show that not only radially polarized modes but also azimuthally polarized modes exist in the laserresonator. In order to guarantee pure radial polarization, the purity of radial polarization needs to be improved bysuppressing azimuthal polarization. The purity of radial polarization depends on refractive index of the substrate andgrating period of the wire grid polarizer. If the substrate of the wire grid polarizer is ZnSe, the purity of radialpolarization can arrive at 85%. When the wire grid polarizer has low refractive index and high ratio of laser wavelengthto grating period, pure radial polarization can be obtained.