Command surface induced switching of the optical properties of liquid crystalline thin film structures

We report on optical waveguide structures with light propagation in a nematic liquid crystalline thin him. The liquid crystal (LC) is sandwiched between two so-called photochromic command layers, consisting of a polymer with azobenzene side chains. When exposed to light of appropriate wavelength, the azobenzene side chains undergo a trans <----> cis isomerization process, inducing a homeotropic <----> parallel change in the LC alignment. These orientational changes affect the set of refractive indices of the LC thin film and, hence, can be detected by optical waveguide methods. As a possible application of the command surface effect in optical waveguide structures, we present an optical switching and information storage device.