Nonlinear Thermal Drift Characteristics in Temperature-Insensitive Silicon Nitride Microring Resonators

The thermal drift of microring resonators is one of the key obstacles hindering their practical applications. Employing polymers with negative thermo-optic coefficients to compensate for temperature-induced wavelength shifts represents a common solution. This study utilizes polymethyl methacrylate (PMMA) to compensate silicon nitride microring resonators, achieving thermal drift magnitudes below 2.0 pm/K within the temperature range of 15℃ to 70℃. Furthermore, nonlinear thermal drift characteristics were experimentally observed, and simulations revealed that these nonlinearities primarily originate from the temperature-dependent Young's modulus and Poisson's ratio of PMMA. This research provides design references for waveguide compensation using negative thermo-optic coefficient materials and proposes a conceptual framework for dual-function devices capable of both athermal operation and thermal tuning.