Thin film/liquid crystal composite optical materials and devices

Using a specialised thin film deposition process called glancing angle deposition (GLAD), one may fabricate porous thin films consisting of isolated columns with highly controllable microstructure. An extensive range of column shapes can be produced by using carefully managed substrate motion during the deposition process. Certain types of GLAD films, such as those possessing helical (or chiral) microstructure, have previously been shown to exhibit unique optical properties including rotation of the plane of polarisation of transmitted light and circular dichroism. The optical response of these GLAD films has been compared to that observed in liquid crystals (LC). When the pores of GLAD films are filled with liquid crystalline materials, the LC molecules take on an orientation governed by the presence and shape of the GLAD film structure, resulting in a new type of composite optical material exhibiting enhanced optical properties compared to those of the film alone. Further, because of their electro-optic characteristics, the LC component in GLAD-LC composite films may be switched by an electric field, yielding switchable devices based on GLAD-LC hybrid materials. This thesis presents an overview of glancing angle deposition and how it leads to the development of GLAD-liquid crystal composite optical materials and devices. Optics based on GLAD-LC composites show potential for improved optical switch and flat panel display technology.