Thermally tunable integrated optical ring resonator with poly-Si thermistor

Doped polysilicon is applied as a thermo-optic heating element to temperature tune the ring resonator based on silicon nitride db waveguides on silicon. The ring diameter is 2 mm allowing a large free spectral range of 26 GHz. For the first time, a poly-Si resistor is used as a thermistor to measure waveguide temperature, The temperature coefficient of the poly-Si thermistor is 9.5 x 10(-4)/degrees C, The reproducibility of the temperature measurement is 0.3 degrees C. The finesse of the ring resonator is 77. The propagation loss of silicon nitride rib waveguide is 0.5 dB/cm at the wavelength of 1.312 mu m. The temperature tuning of the ring resonator and the in situ supervision of the temperature on chip based ore the same poly-Si fabrication profess may find use especially in optical sensor applications.