Thermo-optic simulations of silicon nitride / polymer hybrid waveguides

We perform the thermal and optical simulations of silicon nitride / polymer hybrid waveguides with different heating schemes by finite element method. Both the top and buried microheaters are adopted to realize tuning function by the thermo-optic effect. We find the buried microheater is more energy-efficient than the top microheater in creating a uniformed temperature environment in the waveguide region. On the other hand, the top electrode tends to create a strong temperature gradient through the waveguide, which in turn distorts the optical mode. This distortion, however, is different for TE and TM modes. This thermally induced birefringence effect is thoroughly investigated in this paper.