The synthesis and characterisation of nematic NLO polymer networks

Ultra-fast optical intensity modulators are required for high speed telecom munications and organic electro-optical materials offer the advantages of l ow cost and fast switching capability. We propose a new method to fabricate electro-optical waveguide modulators using low temperature processing and poling with low electric field strength. Our method uses nematic photoreact ive mesogens with large second-order polarisability and low viscosity. They can be poled with an electric field of low strength and simultaneously pho topolymerised to maintain polar order. A nematic mixture with a melting poi nt of 30 degreesC was successfully crosslinked when aligned by an electric field. New tolane based chromophores show second order polarisabilities up to 180 x 10(-30) esu, ten times the value of para-nitroaniline.