Investigation of phase conjugation as a result of a four-wave interaction of YAG:Er3+ laser radiation in organic solvents

The characteristics of four-wave-interaction mirrors utilizing organic solvents were investigated experimentally using YAG:Er³⁺ laser radiation (λ = 2.94 μm). The highest reflection coefficient of 500% was obtained for benzine at an energy density of 2 J/cm² under Q-switched conditions. It was found that distortions introduced by inhomogeneous NaCl phase plates could be compensated by phase conjugation. The longitudinal coherence length of the YAG:Er³⁺ laser radiation was determined from the dependence of the reflection coefficient of a four-wave interaction mirror on the difference between the paths of the signal wave and the parallel pump wave.