Thin Epitaxial Films of Photorefractive Materials

Provided they can be satisfactorily fabricated, the use of thin films of photorefractive material as four wave mixing media for real time holographic application is an extremely attractive alternative to the use of the bulk crystal. For example, because guided wave intensities in the film can be very high-even when using lowered cw laser sources, the response time for holographic recording can be very fast. For example, ~100 mW of power coupled in a ~1 cm wide 1µm thick stripe of BaTiO3 film should reduce the response time from ~1 sec at 100 mW/cm2 in the bulk crystal to ~100 µsec in the film. Furthermore, with thin photorefractive films large area real time phase conjugate mirror operation with low powered laser sources can be contemplated.