Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

Abstract

Temperature measurement: optical barcodes from whispering-gallery sensors Extremely precise measurement of temperature using devices known as whispering-gallery mode (WGM) sensors can be greatly improved using a technique that simultaneously monitors different modes, or patterns, of the optical signals. WGM sensors rely on the sustained circulation of light within closed concave microstructures—discs, rings, or spheres—similar to the movement of sound waves in whispering galleries such as the dome of St. Paul’s Cathedral in London. Jie Liao and Lan Yang at Washington University in St. Louis, Missouri, USA, developed procedures to analyse the effect of temperature on the collective patterns of light signals in WGM sensors. The results are converted into optical barcodes which indicate the temperature directly. This multimode system overcomes significant limitations imposed by the restricted range and less direct monitoring methods of existing single-mode sensors.