SILICA DISPERSED NEMATICS AND CHOLESTERICS FOR BISTABLE HIGH-RESOLUTION DISPLAYS

Highly dispersed silica forms a rebuildable network in nematics capabl e of stabilizing domains of different optical properties. Displays wit h silica dispersed (or filled) nematics can be laser-addressed to a sc attering state, allowing high resolution display applications as well as optical data storage. A theory based on nematodynamics identifies t he laser writing process as a thermal shock effect and corresponds wel l with experimental results. With this knowledge, the sensitivity of t he material was improved using small amounts of chiral dopants. It is also shown that silica dispersed cholesterics with pitch lengths in th e visible range form bistable cholesteric textures (BCT). These filled cholesterics can be laser-addressed to a focal conic transparent stat e or to a reflecting state, depending on the surface treatment of the cell plates.