can be employed to characterize the performance of photorefractive materials. The figures of
merit are the steady-state index change, the response time, the energy per area to write a
grating with 1% diffraction efficiency, and the index change per absorbed energy per unit
volume (photorefractive sensitivity). These indices are evaluated as a function of grating
period and applied external electric field for Bi12Si020, a fast material with a relatively small …