Self-pumped phase conjugation with nanosecond pulses in strontium barium niobate

We report the observation of self-pumped phase conjugation by means of internal reflection in a photorefractive medium produced by a series of intense nanosecond pulses. Nanosecond pulses from a YAG laser ranging in intensity from 9 x 10(4) to 9 x 10(5) W/cm(2) were used. The crystal was rhodium-doped strontium barium niobate. The conjugate signal began with the first pulse, and the time to reach 63% of its equilibrium value scaled as I(-2). The equilibrium reflectivity was 29%. A similar cw experiment with the 514-nm line of an argon laser produced a response time that scaled as I(-1.1).