Linear phase-conjugate oscillator employing a photorefractive crystal

Using Yeh's analytic method [J. Opt. Soc. Am. A 2, 727 (1985)] we derive the oscillation conditions of a linear phaseconjugate oscillator consisting of a photorefractive crystal and two conventional mirrors. For the special case of a 90-rad phase shift, the threshold oscillation conditions of the linear phase-conjugate oscillator are derived as a function of cavity length. The results indicate that, unlike in the case of a phase-conjugate oscillator employing a Kerr-like material, in which oscillation can occur for any cavity length, oscillation can occur in this case only for specified ranges of the cavity length determined by the coupling strength. We also show that for larger coupling strengths oscillation can occur over wider ranges of the cavity length.