Nanokelvin-resolution thermometry with a photonic microscale sensor at room temperature

Ultrahigh-resolution thermometry is critical for future advances in bio-calorimetry(1,2), sensitive bolometry for sensing(3) and imaging(4), as well as for probing dissipation in a range of electronic(5), optoelectronic(6) and quantum devices(7). In spite of recent advances in the field(8-11), achieving high-resolution measurements from microscale devices at room temperature remains an outstanding challenge. Here, we present a band-edge microthermometer that achieves this goal by relying on the strong, temperature-dependent optical properties of GaAs at its absorption edge(12-14). Specifically, using a suspended asymmetric Fabry-Perot resonator and a wavelength-stabilized probe laser we demonstrate a thermoreflectance coefficient of >30 K-1, enabling measurements with a thermometry noise floor of similar to 60 nK Hz(-1/2) and a temperature resolution of <100 nK in a bandwidth of 0.1Hz. The advances presented here are expected to enable a broad range of studies and applications in calorimetry and bolometry where miniaturized high-resolution thermometers are required.

Automated summary

Ultrahigh-resolution thermometry is crucial for various fields including bio-calorimetry, sensitive bolometry, and probing dissipation in electronic, optoelectronic, and quantum devices. However, achieving high-resolution measurements from microscale devices at room temperature remains challenging. This study presents a band-edge microthermometer based on the temperature-dependent optical properties of GaAs, enabling high-resolution measurements.