EFFECT OF PHASE MISMATCH ON THE TRANSVERSE DYNAMICS OF A PHASE-CONJUGATE RESONATOR AT LOW FRESNEL NUMBER

The dynamics of a resonator using an externally pumped photorefractive phase-conjugate mirror is studied experimentally as a function of the phase mismatch introduced by an angular tilt of the pump beam. At the lowest Fresnel number allowing transverse structures (F similar to 2.5), it is observed that spatially inhomogenous patterns are time dependent, periodic in this case, with a diverging period as phase matching is approached. The transverse beam pattern is analyzed using a singular value decomposition revealing two significant eigenmodes oscillating in phase quadrature.