Simultaneous temperature and humidity insensitive race track ring resonator using silicon and titanium dioxide waveguides in cavity

Abstract

We present here a method to achieve temperature-insensitive micro-ring resonator using Si and TiO2 in the racetrack cavity by finite-difference time domain (FDTD) method. Temperature-induced spectral shift in one waveguide is exactly compensated by the optimal length of the other waveguide due to opposite signs of the thermo-optic coefficient of the two materials. Over the span of 40 °C relative to room temperature, MRR undergoes temperature-insensitive state having spectral shift as small as 0.5 pm/°C as compared to 72 pm/°C when TiO2 is not used in the racetrack cavity. The effect of changing core width on temperature sensitivity is also illustrated. We find that temperature insensitivity can only be achieved within a range of the core width. Our method outperforms the often used metal-based temperature compensators in terms of high integration density, low cost, and power dissipation. We have also shown that output response is completely insensitive to variations of relative humidity (RH) in 20% to 60% levels. Due to power confinement in core region and small variations of refractive index in the ambient region, output response is completely insensitive to any variation in humidity.