AUTHOR=Deng Zhi-feng , Zhan Sheng-bao , Wang Ya , Le Wen-ran , Zha Shen-long 

TITLE=Dynamic of Grating Thermal Deformation on Beam Quality for Spectral Beam Combining

JOURNAL=Frontiers in Physics

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.816734

DOI=10.3389/fphy.2022.816734

ISSN=2296-424X

ABSTRACT=For spectral beam combining, an experimental system of dynamic beam quality caused by the thermal
deformation of a grating has been designed and established. According to the theoretical model established, the
distribution of temperature field, as well as the thermal deformation of the grating has been analyzed. Further,
the combined-beam quality and the intensity distribution have been numerically calculated in detail. The results
show that the maximum temperature rises and the thermal deformation increase with increasing irradiation time,
resulting in side lobes appearing in the intensity distribution. In the experiment, the measured combined beam
quality factor M x 2 was 1.29 without the thermal deformation. When the grating was heated by using pump lasers
at different time, the M x 2 can arrive to 1.34, 1.37, 1.41, respectively. The results reveal that the combined beam
quality increases with the increase of irradiation time and changes faster at the beginning of heating, which
consistent with the theoretical analysis. The discussion and analysis of the dynamic beam quality are potentially
valuable for reduce the the influence of thermal deformation on the beam quality.