We demonstrate a new type of optically addressed spatial light modulator. By imaging an external grating into a photorefractive material, we write holographic gratings without the need for interference between our input image and a coherent reference beam. This technique allows us to obtain the high contrast and resolution of photorefractive holography while permitting writing with incoherent input images. We evaluate and discuss various performance parameters such as resolution, contrast, and sensitivity that characterize the device.
© 1991 Optical Society of America
Frederick Vachss, John Hong, and Scott Campbell, "Photorefractive square-law converter," Opt. Lett. 16, 1204-1206 (1991)