Low optical loss perfluorinated methacrylates for a single-mode polymer waveguide

Perfluoroalkyleneoxy methacrylate containing polar functional carbonate (-O-C(=O)-O-) or carbamate (-NH-C(=O)-O-) groups were synthesized to improve optical and adhesion properties of optical waveguide materials. Transparent polymer films were prepared by photocuring of a solution containing methacryloyl perfluoroalkyleneoxy carbonate and a photoinitiator. Optical loss of 0.35 dB/cm at 1550 nm was determined from the photocured film, for TE polarization by measuring the transmitted power along the slab waveguide length. The refractive indices at 1550 nm were determined as 1.4337 and 1.4334 for TE and TM modes, respectively, indicating low birefringence of Δn = 0.0003 ± 0.0002. Adhesion between the substrate and the polymer layer was enhanced by introducing carbonates and carbamates as determined from a SEM cross section and low surface energy of the photocured polymer film. Low-loss optical waveguides have been fabricated from a solution containing methacryloyl perfluoroalkyleneoxy carbonate by photo-cross-linking and then reactive ion etching to produce high-quality channel waveguides with very smooth surfaces. The propagation loss of the channel waveguides was 0.50 and 0.70 dB/cm at the monitoring light of 1550 nm for TE and TM polarizations, respectively.