Self-focusing and self-defocusing of light in two-wave mixing are investigated experimentally. Amplification and self-focusing are measured as functions of the frequency shift between signal and pump beams. A frequency dependence is found in Kramers–Kronig form, as is plausible by the analogy of photorefractive amplification and laser amplification. Reversal of the external dc field on the material or a change in the frequency shift between the signal and pump beams is found to change self-focusing to self-defocusing.
© 1997 Optical Society of America
M. Vaupel, C. Seror, and R. Dykstra, "Self-focusing in photorefractive two-wave mixing," Opt. Lett. 22, 1470-1472 (1997)