Abstract

We report on the detailed observation of dark evolution of photorefractive gratings and induced absorption in BaTiO₃ after illumination with a single 15 ns pulse from time scales of 500 μs to 50 s. The initial photorefractive grating written by the short pulse evolves into three distinct phases: (1) a fast growth component ~50 ms, (2) slow growth component ~2-3 sec, and finally, (3) a ultralong decay ~30 min. Fig. 1 shows a typical dark evolution of the diffracted signal after single pulse writing. The diffracted signal is observed to increase by an order of magnitude in a few seconds.

© 1996 IEEE