Synthesis and Characterization of Methacrylate-Based Copolymers for Integrated Optical Applications

Poly(methyl methacrylate/2-methacryloylethyl methacrylate)-based copolymers of varying composition have been synthesized and characterized. Free-radical polymerization of hydroxyethyl methacrylate and methyl methacrylate over a range of monomer feed ratios gives an ideal random copolymer series which has been functionalized by further methacryloylation of the pendant hydroxyl group. The resulting polymers have been cross-linked both thermally and by UV exposure, as evidenced by infrared and solid-state NMR spectroscopy. After thermal cross-linking the polymers remain stable up to 200 °C. Variation of polymer composition has allowed the refractive index to be tuned between 1.497 and 1.518, a range suitable for waveguide applications, and channel waveguides have been fabricated by UV writing. The propagation loss of these channel waveguides is less than 1 dB/cm at a range of near-IR wavelengths.