Loop oscillator with a holographic amplifier

A report is given of the first loop oscillator utilizing a photorefractive barium sodium niobate crystal and a holographic amplifier with a similar crystal inside the loop. It is shown that the amplifier reduces the threshold value of the coupling constant and increases the reflection coefficient of a phase-conjugate wave (the maximum value found in these experiments was ~ 50%). The conditions for optical bistability in this loop are considered.