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Abstract
A high-resolution photonic thermometer article performs high-resolution thermometry and includes: a light source; a photonic thermometer with a waveguide and a photonic crystal cavity that stores light; a photodetector in communication with the photonic thermometer; a phase sensitive detector in communication with the photodetector and that: receives the photodetector signal from the photodetector; receives a reference frequency signal; and produces a lock signal from the photodetector signal, based on the reference frequency signal; a local oscillator in communication with the phase sensitive detector and that produces the reference frequency signal; and a servo controller in communication with the phase sensitive detector and local oscillator and that: receives the lock signal from the phase sensitive detector; receives the reference frequency signal from the local oscillator; and produces the control signal such that absorption power of the photonic crystal is maximized through wavelength control of the light source by the control signal.
Patent Description
NIST has created a method that sense temperature variations on a µK-level using an on-chip integrated passive photonic device that features a high-quality factor nanocavity. The method includes the (i) improved design of nanobeam photonic crystal cavity, (ii) specialized fiber coupling and chip-packaging that remove the long-term drift of the resonant frequency of the optical of the cavity, as well as (iii) an interrogation laser locking technique to read out resonance frequency of the sensor that is highly sensitive to even ultra-small temperature variations. Currently, ultra-high-resolution thermometry is achieved with Standard Platinum Resistance Thermometers (SPRTs). Photonics-based nanosensors with µK-level temperature resolution has the potential to replace the resistance-based thermometry and the way temperature is disseminated world-wide. High quality factor photonic sensors when coupled with laser locking techniques already show resolution and repeatability that is on par or better than SPRTs. The results of this invention show the potential for photonic nanoscale sensors to serve as future standards for the dissemination of the International Temperature Scale of 1990 (ITS-90) to commercial calibration laboratories and as transfer standards for international measurement comparisons between National Metrology Institutes.
Features
Photonics-based nanosensors with µK-level temperature resolution can potentially outperform SPRTs in (i) resolution, (ii) repeatability/hysteresis, (iv) operation speed, (v) size of the sensor, (vi) reliability. Their calibrations, in contrast to SPRTs, will be almost or completely unaffected by mechanical shock or thermal stress, which will enable ultra high resolution thermometry to be readily deployable to industry customers.