Erasure rate and coasting in photorefractive barium titanate at high optical power

The light-induced erasure rate of a photorefractive grating in barium titanate scales sublinearly with optical intensity over a range spanning 8 orders of magnitude. Additionally, we find that a series of optical pulses is more efficient in erasing a photorefractive grating if the repetition rate of the pulses is decreased. We postulate that this increase in erasure efficiency is caused by a level of shallow traps in the crystal, which permit erasure to continue for a few seconds in the dark after the optical pulse has ended, and we directly observe this coasting in the dark.