Photorefractive oscillators that use internal-reflection modes

Using the grating-action method, we analyze the operation of photorefractiv e oscillators that use internal-reflection modes of the crystal. We show th at the oscillators interacting with the lossless internal modes possess no thresholds for coupling strengths and require no finite input seed for stab le operation. The onset of oscillation is like a second-order phase transit ion, in contrast to the lossy oscillators, whose onset is like a first-orde r phase transition. (C) 2000 Optical Society of America [S0740-3224(00)0161 1-8].