Spectral behavior of phase conjugated mirror in a two-pass optical amplifier

In this paper، the spectral behavior of a two-cell phase conjugated mirror (PCM) with a two-pass Nd: YAG amplifier has been analyzed experimentally and theoretically. For this purpose، amplifier input intensity for the three different states of laser oscillator with one، two and three longitudinal modes have been investigated. The numerical model is based on 2-dimension equations of stokes back-scattered intensity and acoustic wave، for two-cell generator-amplifier phase conjugated mirror with proper boundary conditions and simultaneously solving the rate equations of Nd: YAG optical amplifier. Results of the Fourier analysis of the amplified intensity show considerable differences between Fourier amplitudes of the amplifier equipped with PCM and a two-pass amplifier with a conventional turning mirror under the same output energy. The amplifier with PCM has a completely filtered and different spectral behavior with clearly reduction of the beating between Fourier components of the input optical field.