We report electrical switching of the diffraction efficiency in volume
Bragg gratings written holographically in polymer-dispersed liquid cr
ystals (PDLCs). Scanning electron microscopy confirms the volume natur
e of the gratings and shows that they consist of periodic PDLC planes.
The diffraction efficiency can be switched from a high value (approxi
mately 50%) to a value near zero at fields approximately 11 V/mum.