ABSTRACT
The process of SBS works most effectively at moderately high peak power (MW) with pulsed operation (10 ns), corresponding to pulse energies 10-100mJ. At lower powers the process will be below threshold and the efficiency is too low to be practical in most laser applications. Even above threshold the efficiency may still not be as high as required. Only at many-times threshold power does the reflectivity of the process reach near unity. At very high intensities, however, the SBS process can also be disrupted by detrimental competing nonlinearities (e.g. Kerr self-focusing, thermally-induced defocusing and SRS) and also degradation of the SBS material (e.g. light induced breakdown, thermally-induced convection, bubble formation). A further issue is the need to achieve good quality phase conjugation, requiring selection of the conjugate from noise components, which is also negatively impacted by competing nonlinearities. A still further issue is the transiency of the SBS process that dictates the range of pulse duration that can be used. The net result is that SBS may only operate over a narrow range of laser powers and pulse durations for a given SBS medium and interaction geometry.
