Spatial filtering in near field based on rotating and polarizing property of crystal

In transfer and amplification system of laser, spatial filtering is a key to improving the quality of output light. Based on rotation effects of polarized light in an isotropic crystal, the polarized light with spatial variation components might pass through or be cut off by polarization selectivity, spatial filtering of light in near-field is feasible. Furthermore, combined filters can improve narrow-band filtering. The proposed method is able to reduce the system space and energy consumption in the spatial filtering system.