Spatial phase shift during hologram writing in lithium niobate

Abstract

The spatial phase shift between the sinusoidal light pattern and the phase hologram which it writes was obtained first from beam coupling measurements, and secondly by shifting the writing light pattern with respect to the hologram being written using a piezoelectrically driven mirror until beam coupling was reduced to zero. The effective phase shift increased with exposure. Extrapolated back to zero exposure a value of 5° was obtained corresponding to a transport length in the bulk photovoltaic effect of 13 nm about half that previously estimated from beam coupling after significant exposure.