Finite element analysis of thermo-optic integrated photonic devices

Integrated photonic devices are particularly sensitive to temperature variations. This work describes a numerical approach to evaluate the influence of the optical waveguide beating on the wave propagation properties. The finite element method (FEM) was used to perform both the stationary and linear thermal analysis and the optical modal studies. The refractive index profiles of Ti:LiNbO₃ waveguide, as a function of fabrication parameters are taken into account employing an analytical solution of the 2D linear-stationary diffusion equation. The thermo-optic effect changes the refractive indexes at the waveguide region. The refractive indexes variation can be evaluated by using a model based on experimental data. Finally, the modal analyzes of Ti:LiNbO₃ waveguides perturbed by the thermo-optic effect were performed. Two devices were studied: a thermo-optic phase shift modulator and a thermo-optically induced waveguide switch (cutoff switch).