Optical device enhancement method and apparatus by control of stimulated brillouin scattering gain

摘要

The output of an optical device which involves a stimulated brillouin scattering (SBS) gain medium is enhanced over a range of input beam intensities by providing a gain medium which has a given SBS gain for a given input beam intensity, and modifying the gain medium to reduce its SBS gain coefficient. By lowering the SBS gain coefficient, SBS dominance and suppression of stimulated Raman scattering (SRS) can be mitigated, and the output fidelity of a phase conjugation system with respect to its input can be significantly enhanced. Mechanisms for reducing the SBS gain coefficient include increasing the medium viscosity, thermal conductivity and/or diffusion coefficient, or causing the medium relaxation zone to coincide with the frequency of the phonons involved in the SBS process. Two different media can be mixed together in varying proportions to progressively modify the overall medium SBS gain as the input beam intsnsity is progressively changed.