Propagation loss and birefringence properties around 1.55 μm of polymeric optical waveguides fabricated with cross-linked silicone

We newly synthesized cross-linked silicone from methyl and deuterated phenyl (d-phenyl) groups in various amounts and used the resultant polymers to fabricate single-mode optical waveguides. We measured the losses and birefringence of the waveguides by the cutback method and Senalmont ellipsometry, respectively. The propagation loss decreased as we increased the d-phenyl content. The propagation loss was 0.23 dB/cm at 1.55 μm for a waveguide fabricated using cross-linked silicone with a 95-mol.% d-phenyl content. In contrast, the birefringence increased with increasing d-phenyl content. This indicates that the increase in phenyl content influences the orientation of optically anisotropic phenyl groups in the film, resulting in a birefringence increase. The birefringence value was 2.0×10⁻⁴ for a waveguide fabricated from cross-linked silicone with a 27-mol.% d-phenyl content.