TRANSIENT-RESPONSE OF A PHOTOREFRACTIVE GRATING PRODUCED IN A BSO CRYSTAL BY A SHORT LIGHT-PULSE

The transient photorefractive properties of a BSO crystal after illumi nation by two coherent light pulses were studied by monitoring the dif fracted beam intensity of a HeNe laser beam. The previously observed p eculiar response curve, having a dip between the first fast rise and s econd slower rise, can be explained by a newly developed ''four-level' ' model with two shallow acceptor levels, an inactive ionized acceptor level, and a donor level. The temperature dependences of transient ph otorefractive properties and transient photocurrent, which were measur ed for the first time, also support the present model.