Research on A High-Sensitivity Temperature Sensor with Multi-Indicator Based on Nano-Cylinder-Loaded Ring Resonator

Increasing sensor sensitivity and maintaining a large FOM (figure of merit) are challenging to achieve at the same time. Adding grooves and asymmetrical structures to the annular cavity increases sensitivity; however, it usually makes the FOM of the structure decrease. Herein, we propose a MIM (metal-insulator-metal) sensor of a novel structure with nano-cylinders loaded in a ring resonator (NCRR), whose sensitivity can reach as high as 3636.4 nm/RIU (refractive index unit). The FOM is maintained around 2000 in the mid-infrared (MIR) region. We find that grating effects only occur in the ring cavity when the cylinder's distance is below three times its radius, and it can improve the sensitivity of the proposed structure up to 42.3% without decreasing its FOM. In addition, results suggest that our sensor has excellent resistance to eccentricity, which brings in manufacturing. Furthermore, we investigate the capability of the proposed device as a temperature sensor with ethanol, which exhibits a maximum temperature sensitivity of 1.48 nm/degrees C. We believe that our research has essential application prospects in miniature integrated sensors, optical switches, splitters, filters, and broadband passers.