Analysis of temperature profiles of thermo-optic waveguides

The temperature profiles of thermo-optic waveguides are analyzed by the finite element method. The heat generated by a thin-film heater causes the temperature of a nearby waveguide to increase. The analysis results show that thermal coupling is a function of the waveguide spacing and depth. Thermal coupling increases with the waveguide depth but decreases with the waveguide spacing. Thermal coupling could be reduced by placing a cooler on the adjacent waveguide or etching a deep trench between the waveguides. The cooler can reduce the coupling, but it is not effective for deep waveguides. For the trenched structure, the temperature of the heated waveguide increases as the trench depth increases; however, the temperature of the nearby waveguide will decrease.