Material Investigation of Alicyclic Methacrylate Copolymer for Polymer Waveguide Fabrication

Abstract

We investigated the physical and chemical properties of alicyclic methacrylate copolymers and their changes under deep-UV exposure. It was shown that alicyclic methacrylate copolymers have a better thermal stability and a higher refractive index than conventional poly(methyl methacrylate) (PMMA). Fourier transform IR (FTIR) spectra show the scission of the carbonyl group of the alicyclic methacrylate copolymers by deep-UV exposure similar to that of PMMA. This structural modification results in a local and controllable increase in refractive index in the exposed areas of the polymer surface. We fabricated polymer waveguides from alicyclic methacrylate copolymers by conventional photolithography using quartz/chromium mask. The minimum propagation loss of the straight waveguide with a 7.5 µm width was 2 dB/cm at 1550 nm.