Thermally stable optical waveguide using polycarbonate

Thermally stable polymer waveguide was fabricated using polycarbonate as the core material. Polycarbonate is thermally stable up to 190°C, has small birefringence of 0.003 and good optical transparency at 1.3 μm. We used Cyclotene 3022 as the cladding material. The material has 0.45% lower refractive index than the core material, resulting in a good mode matching waveguide with a single mode silica fiber. Buried channel waveguides were fabricated by conventional photolithography and dry etching technique. The thickness of the guiding layer was 5.3 μm and the width of the waveguides varied from 3 to 8 μm. The etched patterns were smooth and almost vertical. The waveguide operated in single mode up to 7 μm with the mode size of 12 μm. They showed an optical loss of less than 0.8 and 1.4 dB/cm at the wavelength of 1.3 μm for TE and TM polarizations, respectively.