Improved Brillouin enhanced four-wave mixing using dual injection seeded lasers

Abstract

A high reflectivity Brillouin enhanced four-wave mixing (BEFWM) phase conjugator utilizing two separate injection seeded Nd:YAG lasers is described and compared to the more traditional method of producing BEFWM using stimulated Brillouin scattering (SBS) to generate the Brillouin Stokes shifted pumps. The gigahertz level frequency offset between pump and probe necessary to induce high reflectivity BEFWM is simply generated by tuning the relative frequencies of the seed lasers. By eliminating the SBS generated pumps, which are required at energy levels that challenge the photochemical stability of the SBS material, a significant source of noise for BEFWM is removed. The result is improved BEFWM performance using dual injection seeded lasers. This improvement is manifested by enhanced probe sensitivity down to tens of picojoules as well as decreased long- and short-term fluctuation in BEFWM output and improved phase conjugate fidelity.