Birefringence compensated silica-based waveguide with undercladding ridge

A novel waveguide structure with an undercladding ridge designed to compensate for the birefringence of silica-based waveguides is proposed. The proposed structure was applied to a 16-channel arrayed-waveguide grating, and successfully demonstrated low polarisation dependence (<0.01 nm) without any degradation in waveguide characteristics.