THEORETICAL STUDY OF THE INTENSITY DEPENDENCE OF TOTAL EFFECTIVE TRAP DENSITY IN PHOTOREFRACTIVE CRYSTALS

Intensity dependence of the total effective trap density N_eff is studied theoretically for the two-centre and the three-charge-state photorefractive crystals. The results show that N_eff always increases with increasing intensity in three-charge-state crystals, whereas it has more complicated behaviors in two-centre crystals. When S_Dγ_T/S_Tγ_D is small, N_eff increases and tends to saturate with increasing intensity for both type-A and type-B two-centre crystals. When S_Dγ_T/S_Tγ_D is large, N_eff increases to a maximum and then decreases a little for type-A crystals and decreases greatly for type-B crystals. The different intensity dependences of N_eff in the two types of crystals come from their different level structures.     

INFLUENCE OF BEAM POLARIZATION ON THE PERFORMANCE OF A MUTUALLY PUMPED PHASE CONJUGATOR

The influence of polarization variation of a pump beam on the performance of a “bridge” mutually pumped phase conjugator has been investigated. The reflectivity, transmission, and response time were measured for different polarizations and different intensity rations of input beams. From these measured results, the variation behaviors of parameters of fourwave mixing interactions in the crystal are revealed.