Noise radiation power of phase-conjugate mirrors based on a degenerate four-wave mixing

An experimental investigation was made of the influence of the state of optically polished surfaces of various materials on the scattering coefficient which governs the power of the intrinsic noise of phase-conjugate mirrors based on a degenerate four-wave interaction. The angular dependence of this coefficient was also investigated. The noise power of a phase-conjugate mirror made of InAs, operating at the optimal pump wave intensities 1— 2 MW cm^-2, may be reduced to ~2 × 10^-7 W per one spatial mode of the radiation to be phase-conjugated. This was achieved by increasing the angle between the axes of the signal and the pump beams up to ~1 rad without a significant reduction of the reflection efficiency, which can be ~500%.