Extremely nonlinear photosensitive liquid crystals for image sensing and sensor protection

Optically induced nematic liquid crystal axis reorientation results in extr aordinarily large nonlinear refractive index changes that could find practi cal applications in conjunction with cw or long-pulse lasers. We discuss th e origins of these nonlinearities, and present the results of recent experi mental studies of image conversion, optical limiting and sensor protection using aligned dye-doped nematic liquid crystal films in all-optical configu rations. These processes are characterized by unprecedented low threshold l aser powers, thus presenting nonlinear photosensitive nematic liquid crysta ls as promising next generation image processing and optical switching/limi ting material. (C) 1999 Optical Society of America.