Photonic Thermometry is a cutting-edge research program at NIST that aims to break the fundamental limitations of electrical resistance-based thermometry and open new horizons for temperature measurement science. The main three goals of Photonic Thermometry are: (1) to realize new field-deployable, chip-scale, photonics-based quantum SI (qSI) sensors and primary standards for temperature; (2) to revolutionize realization and dissemination of temperature; and (3) to create an integrated nanophotonics platform to enable novel sensing applications. Being a synergy of various research fields, the program combines recent advances in state-of-the-art nanofabrication, integrated nanophotonics, high-performance optomechanical devices, and optical frequency metrology. Photonic Thermometry is part of NIST on a Chip (NOAC) program.
Temperature measurement is critical to innumerable industries – precise, accurate, and rapid temperature sensing enables much of the modern technology on which we depend. Most of these temperature sensors are based on a temperature-dependent resistance measurement of a strain-free metal wire or thin film such as platinum resistance thermometers (PRTs). Although these sensors are often the best option available, they are sensitive to environmental conditions and mechanical shock, and may drift over time. Photonics-based temperature sensors have the potential to bypass these limitations and to avoid costly and disruptive recalibration of sensors.
Photonic temperature technology weds high sensitivity (capable of out-performing the state-of-the-art Standard Platinum Resistance Thermometers (SPRTs)) with the practical advantages of chip-based photonics technology – low cost, portability, and near-immunity to electromagnetic interference. It enables sensors that can be deployed in a wide variety of settings ranging from controlled laboratory conditions to a noisy factory floor to the variable environment of a residential setting.
The NIST Photonic Thermometry program is pursuing three related goals.
We are developing an ultra-stable, high-resolution photonic temperature sensor device that exploits the thermo-optic effect to translate thermal changes into optical frequency shifts. This practical device has the potential to displace traditional resistance-based sensors in many applications.
In parallel, we are pursuing research in cavity optomechanical devices that can measure thermodynamic temperature. These nanoscale devices can simultaneously be sensors and primary standards, which are self-calibrating using quantum fluctuations. Such Standard Photonic Thermometer (SPoT) devices have the potential to supplant the International Temperature Scale of 1990.
Finally, we are developing a photonics-based platform that leverages advances in photonic thermometry to enable novel sensing applications, including current work in photonic humidity, photonic dosimetry (spun-off as a separate NOAC project), broadband photonic imaging array, and chip-scale AC-DC transfer standard.
Photonic temperature sensors generally rely on the way heat changes the dimensional and thermo-optic properties of miniaturized photonic resonator devices, such as ring resonators and photonic crystal cavities, creating an optical filter whose spectral characteristics are a sensitive measure of temperature.
Optomechanics-based thermodynamic thermometryuses a quantum-based, calibration-free device, which senses thermally-driven Brownian motion of a nanomechanical resonator – a quantity that is determined by the absolute temperature of the sample. This motion is read out with a cavity-enhanced optical probe. The thermal Brownian motion can be calibrated using the quantum fluctuations of the mechanical resonator, so the system can serve as on-chip photonic primary standard.
We are seeking partners from the U.S. private sector, national laboratories, and academia to join us in the development of cutting-edge measurement technologies that will be incorporated into real-world tools and revolutionize the metrology landscape. If you are interested in joining our team as a post-doc, guest researcher, collaborator, or student volunteer, or if you would like to visit the lab and see the latest developments in thermodynamic metrology, send us an email.