Thermo-optic tuning of erbium-doped amorphous silicon nitride microdisk resonators

Abstract

We demonstrate a technique to yield a direct and sensitive measurement of the thermo-optic coefficient (TOC) for light-emitting materials in optical microdisk resonators. Using photoluminescence from erbium-doped amorphous silicon nitride (a-SiNx:Er) as an example, we show how the TOC can be extracted from thermally induced shifts in the resonant microdisk modes. For the highest-performance a-SiNx:Er material composition, we find a TOC at 1.54 μm of ∼3×10−5 K−1 in the 300–500 K range. Additionally, our work demonstrates a convenient all-optical spectroscopic technique for sensitive temperature measurements, with a resolution of ∼30 mK in this temperature range.