基于多子束拍频叠加的集束偏振动态调控技术OA

The dynamic polarization schemes based on the beat superposition of multi-beamlets were proposed to suppress the growth of laser-plasma instabilities(LPIs),such as backward stimulated scattering.The basic principle is to utilize the beat superpo-sotion of multiple beamlets within the laser quad,combined with independent control of the beamlets'amplitude spectra,phase spectra and polarization,to randomize the spatiotemporal distribution of the polarization for the superimposed laser field,including the superpo-sition of complementary smoothing by spectral dispersion phase modulated beamlets,counter-rotating phase modulated beamlets,non-homologous spectral incoherent broadband sub-beams,multi-spectral incoherent broadband sub-beams with different spectra,and multi-spectral time-phase modulation sub-beams.The results show that,using the superposition effects of multiple beamlets with identi-cal amplitude spectra but different phase spectra and orthogonal polarization,polarization dynamic control on the order of picoseconds or even sub-picoseconds can be achieved,whose time scale of the polarization variation is determined by the bandwidth of a single beam-let.Further,by using the superposition of multi-color beamlets with different amplitude spectra and orthogonal polarization,the time scale for the polarization variation of the superimposed laser field is determined by the frequency shift between the beamlets and the number of the beamlets,which can significantly relax the bandwidth requirements of a single beamlet without degrading the depolarizing and smoothing performance of the laser field on the target plane,providing a theoretical reference for comprehensive dynamic control of target-field bandwidth,polarization and intensity aimed at LPIs suppression.