Liquid Crystal Elastomers for Integreated Optics

Abstract

The chemical crosslinking of the linear LC-side chain polymers yields elastomers (rubbers) which exhibit the liquid crystalline state. The mechanical deformation of these elastomers by elongation or compression causes a macroscopic orientation of the liquid crystalline molecules linked to the polymer network similar to the electric field orientation of low molar mass liquid crystals. In this way elastomer films can be prepared, whose macroscopic optical properties are similar to the optical properties of an anisotropic single crystal having the same dimension. There is, however, an additional feature to these elastomers: a local deformation of the macroscopically aligned film causes a local chance of the optical properties. If the plane surface of the film is brought in contact with a stamp, which has a defined pattern in the micrometer range, the pattern deforms the elastomer surface and consequently the local direction of the optical axis. It is obvious that this procedure enables the simple realisation of elements for the integrated optics. The light conductors can be mechanically pressed into the liquid crystalline elastomer film (similar to the production of a record) and durably stored in the glassy state.