Whispering Gallery Mode Resonators for Precision Temperature Metrology Applications.

Area of Science:

• Physics
• Metrology
• Materials Science

Background:

• Accurate temperature measurement is crucial in scientific and industrial applications.
• Existing thermometers like platinum resistance thermometers have limitations in certain applications.
• Whispering gallery mode (WGM) resonators offer unique properties for sensing applications.

Purpose of the Study:

• To develop and characterize a novel thermometer based on sapphire whispering gallery mode (WGM) resonators.
• To evaluate the performance of the WGM resonator thermometer in terms of temperature resolution and uncertainty.
• To assess the potential of this WGM sensor as an alternative to conventional thermometers.

Main Methods:

• Fabrication of a cylindrical sapphire microwave resonator within a gold-plated copper cavity.
• Excitation of WGM standing waves using coaxial cable antennas at microwave frequencies.
• Precise measurement of resonance frequencies to determine temperature.

Main Results:

• The developed sensor demonstrated a high quality factor, enabling precise temperature measurements.
• Achieved a temperature resolution better than 15 µK.
• Obtained a measurement standard uncertainty of 1.2 mK, significantly outperforming previous methods.

Conclusions:

• The sapphire WGM resonator thermometer offers a promising new technology for high-precision thermometry.
• Its performance suggests it could serve as a transfer standard or interpolating instrument for the kelvin.
• This WGM sensor presents a viable alternative to platinum resistance thermometers in various applications.