Difference-frequency-generated holograms of two-dimensional objects

We demonstrate both analytically and experimentally that second-order nonlinear interaction in a uniaxial crystal produces a holographic replica of one of the incident fields. In particular, we consider difference-frequency generation and directly calculate the field transformation that is produced by the nonlinear interaction for some simple but nontrivial two-dimensional objects, such as a long wire, a circular hole, and a regular net. Finally we show experimental results for such objects that validate the theoretical calculations. (C) 2004 Optical Society of America.