High Resistant Phase-conjugated Stimulated Brillouin Scattering Mirror Using Fused-silica Glass for Nd:YAG Laser System

A fused-silica glass showed a high stimulated Brillouin scattering reflectivity excess of over 90% at an incident energy of 200 mJ for a 18-ns pulse duration. It was found that the strong thermal lens effect in a Nd:YAG amplifier of focal length less than 1 m was easily compensated by a phase-conjugating mirror based on stimulated Brillouin scattering of a fused-silica glass. An output power of 7.2 W at 10 Hz could be delivered without changing the transversal beam profile. The lower absorption and higher thermal shock parameter of the fused-silica will give the maximum operation level at over 3 kW of incident power with 90% reflectivity.