Multimode sensing using optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

Precise temperature measurement is highly desirable in many scientific, engineering, and industrial areas. Optical sensors based on Whispering-Gallery-Mode (WGM) microresonators offer the advantages of high sensitivity, high resolution, and small footprint. However, conventional sensing methods rely on tracking the changes in a single-mode, which limits the dynamic range of the measurement. We demonstrate an optical WGM barcode technique involving simultaneous monitoring of the patterns of multiple modes that can provide a direct temperature readout from the spectrum. This work lays the foundation for developing a high-resolution temperature sensor with superior sensitivity over a broad dynamic range.