Thermally stable hybrid organic/inorganic resonant cavities

Silica optical microcavities experience linewidth broadening and resonant frequency instability as a result of their high Q factors. One of the causes is the thermo-optic effect or temperature induced changes in refractive index. For many telecommunications and biodetection applications, it is critical to have a stable, temperature independent, resonant frequency. In this research, silica microtoroid resonators are coated with two different polymers: polymethylmethacrylate (PMMA) and polystyrene (PS). The hybrid device has minimal thermal response with proper film thicknesses depending on the polymers because the positive dn/dT of silica is balanced by the negative dn/dT of the polymer. The results follow theoretical predictions based on finite element method simulations.