Influence of thermal deformations of resonators on propagation properties of laser annular beams through turbulent atmosphere

Based on the laser field from a positive confocal unstable resonator, considering the influence of thermal distortion of the internal resonator mirror on the annular beam, the propagation characteristics of the annular beam through turbulent atmosphere are investigated by means of the fast Fourier transform algorithm (FFT). The intensity distributions of the output laser far-field are obtained to analyze the propagation characteristics of laser annular beam through the turbulent atmosphere, which is a function about different propagation distances. The results show that the peak intensity of the laser pattern becomes depressed and the spread of the far field diagram patterns is broadened under the increasing of the transmission distance and the thermal distortion of the laser resonator. β-parameter and strehl ratio are introduced to estimate the annular beam quality characteristics. It is found that the annular beam through strong turbulence influences much less obviously than the annular beam through weak turbulence on the quality characteristics with thermal distortion. In the same atmospheric conditions with a certain distance, the greater the mirror thermal distortion is, the worse the annular beam quality characteristics is.

► We consider the mirror thermal distortion influence on the annular beam quality.
► We investigate and study the influence of thermal distortion on propagation properties.
► The intensity distributions is a function about different propagation distances.
► We analyze and compare the intensity distributions with and without turbulence.
► The smaller the mirror thermal distortion is the better the quality of the annular beam is.