Agile Plasmo-Photonic Interferometric Sensor With Liquid Dielectric Loading for Temperature Sensing and Thermo-Optic Coefficient Measurements

This work presents an integrated plasmophotonic interferometric sensor providing environmental temperature and thermo-optic coefficient (TOC) measurement capabilities. By exploiting extreme light field concentration on the plasmonic metal stripe, the sensor employs a liquid dielectric layer deposited on the plasmonic sensing area for refractive index changes versus temperature. Experimental characterization was conducted with four different liquids, achieving a record temperature sensitivity of +23.86 nm/°C for a 70% ethanol–water solution. Additionally, by leveraging the sensor’s high sensitivity, the TOC of an unknown liquid was determined with a relative error of 13.1%.