Frequency shifts and dynamic instabilities in photorefractive self-pumped and mutually pumped phase conjugation

Frequency shifts and dynamic instabilities in photorefractive cat self-pumped phase conjugators and bridge mutually pumped phase conjugators are studied by use of a two-dimensional model. Intrinsic electric fields inside the crystals induce the frequency shifts and dynamic instabilities observed in these experiments. In eat mirrors, for small values of the electric field the phase-conjugate reflectivity and the frequency shift, are constant. With a further increase in the electric field the reflectivity and the frequency shift become periodic through Hopf bifurcation. For a large value of the electric field both the reflectivity and the frequency shift fluctuate chaotically. In bridge mirrors, for small values of the electric field the phase-conjugate reflectivity is stable; and no frequency shift exists. With a further increase in the electric field the reflectivity and the frequency shift become periodically oscillating in time. For a large value of the electric field both the reflectivity and the frequency shift fluctuate chaotically. The phase-conjugate outputs of the two beams oscillate in an almost synchronous manner. (C) 1999 Optical Society of America [S0740-3224(99)00703-1]. OCIS codes: 190.5040, 190.5330, 190.4380, 190.3100, 190.2640.