Silica-waveguide thermooptic phase shifter with low power consumption and low lateral heat diffusion

A thermooptic (TO) phase shifter consisting of a thin film heater on the top of a loaded stripline silica waveguide on a silicon substrate is shown to exhibit faster time response than reported for phase shifters based on a buried silica waveguide configuration. The risetime was measured to be 0.24 ms, which is in good agreement with calculated thermal distributions in the structures. The lateral heat diffusion distance in the loaded stripline structure is shown to be smaller than in buried waveguide structures. This implies small thermal crosstalk and suggests a high-level integration of adjacent waveguides.<>