We demonstrate a photorefractive incoherent-to-coherent optical converter driven by ultraviolet light that provides a 35-μs response time and an optical resolution of 124 line pairs/mm. The device, implemented in KNbO<sub>3</sub> , operates with a modulating intensity of 85 mW/cm<sup>2</sup> , which corresponds to an optical switching energy per bit of 0.5 pJ. A conversion rate of the order of 90 Gbits/(s cm<sup>2</sup>) is achieved. The conversion between the ultraviolet light and the visible laser beam at λ=532 nm occurs through anisotropic Bragg diffraction at a modulated interband photorefractive grating. Our device has a better optical resolution and conversion rate than optically addressed solid-state spatial light modulators based on the photorefractive effect and multiple quantum wells, and it is also faster than devices based on liquid crystals.
© 1999 Optical Society of America
P. Bernasconi, G. Montemezzani, M. Wintermantel, I. Biaggio, and P. Günter, "High-resolution, high-speed photorefractive incoherent-to-coherent optical converter," Opt. Lett. 24, 199-201 (1999)