We demonstrate accurate two-dimensional mapping of the phase retardation induced by the electro-optic effect in lithium niobate crystals. Off-axis digital holography is used to investigate congruent z-cut crystals. The spatially resolved optical path difference is interferometrically measured while a linearly rising voltage ramp is applied to the crystal. This procedure provides information on the uniformity of crystals' electro-optic properties and offers the ability to detect the presence of defects that is of fundamental importance for reliable processing of photonic devices.
© 2005 Optical Society of America
M. de Angelis, S. De Nicola, A. Finizio, G. Pierattini, P. Ferraro, S. Grilli, M. Paturzo, L. Sansone, D. Alfieri, and P. De Natale, "Two-dimensional mapping of electro-optic phase retardation in lithium niobate crystals by digital holography," Opt. Lett. 30, 1671-1673 (2005)