A thermal model for silicon-on-insulator-based waveguide modulators

In the proposed thermo optic modulator a metal heater, deposited on the top of a SOI rib, generates thermal energy. It is assumed that the waveguide structure is infinite in extent in the direction of the propagating wave (into the page). Consequently longitudinal heat flow can be neglected and only the cross-sectional temperature distribution is studied. Heat transfer from the heater to the air cladding is also neglected. By controlling the electrical power applied to the heater the temperature profile inside the structure, and hence the associated change in refractive index, can be calculated. The present paper focuses on the thermal design.