Research on the influence of impurity particles on the optical breakdown threshold value of stimulated Brillouin scattering medium

Abstract

In this paper, we establish the physical model of hot damage to the stimulated Brillouin scattering (SBS) medium, and with numerical simulation method the curve of the temperature of impurity particles versus the radius is investigated. The result indicates that impurity particle has a maximal thermal effect radius and when the sizes of particles contained in the medium are near the radius, the optical breakdown phenomenon is most likely to appear, and at this point the optical breakdown threshold is lowest. We use FC-3283, GF-180 and HFE-7100 as the SBS medium in Continuum Nd: YAG laser system. The SBS medium passes through the filter with different diameters. We study the optical breakdown thresholds and energy reflectivities before and after filtration. It is demonstrated that with the filter diameter decreasing, the optical breakdown threshold increases gradually and the energy reflectivity is significantly improved through filter. In addition, a method of using He-Ne laser transmission light spot size to judge whether optical breakdown phenomenon happens, is also developed. This method is convenient and accurate, and can effectively reduce the error caused by naked eye observation.