RECORDING OF A RUNNING GRATING BY A STANDING INTERFERENCE PATTERN IN A PHOTOREFRACTIVE CRYSTAL

In contrast to the previously reported phase-locked detection scheme, we suggest the recording of a running grating exp(iqx - i Omega t) of charge density in a photorefractive crystal when the interference patt ern exp(iqx) is a standing one. It may be achieved by application to t he crystal of an electrical field which contains both DC and AC compon ents. Coincidence of AC frequency Omega with that of charge density wa ves for the given E(DC) and q results in a resonant enhancement of the process.