High reflectivity SBS phase conjugate mirror

摘要

This paper reports studies of the performance of a phase-conjugate mirror (PCM) with its operation based on the stimulated Brillouin scattering (SBS) of the focused laser beam in ultra-pure fluorocarbon FC-75 (C_8F_(18)). A pulsed laser with 15-ns pulse width from a home-made injection seeded single frequency MOPA configuration Nd:YAG laser with variable output energy (from several mJ to 300 mJ) was used as a coherent light source in these experiments. The PCM reflectivity better than 90% has been achieved at optimized focusing conditions of an incoming beam, and the output energy of the phase conjugate pulse linearly followed the input pulse energy after reaching the threshold level of about 3.3 mJ. The slope efficiency was estimated to be approximately 95% without taking into account of losses in some optical components, including the thin film polarizer. We believe that a higher level of PCM efficiency can be achieved with more careful selection of the critical optical components, including the thin film polarizer, quarter-wave plate and focusing lens.