Electro-Optic Polyimide Thin Films for Integrated Photonic Interconnects on Silicon

Abstract

Using dielectric relaxation spectroscopy we have determined that commercially available polyimides exist which are highly suitable as hosts for nonlinear optical (NLO) molecules. In general, polyimides offer excellent thermal and mechanical properties as a host material but have, until now, presented some difficulties in the poling process.1 We now process and pole polyimide thin films similarly to the techniques used in our successes with electro-optic waveguide devices made from methacrylate based material systems.2 As seen in Fig. 1, the transition from glassy to rubbery states in the Hitachi LQ2200 optical quality polyimide (available for use in liquid crystal displays) occurs near 250 °C. We have found NLO molecules compatible with LQ2200 that shift the glass transition temperature, Tg, down (up) by plasticization (anti-plasticization) of the host correlating to the NLO molecules melting temperature being lower (higher) than the Tg of the pure host LQ2200.