High-sensitivity Fano resonance temperature sensor in MIM waveguides coupled with a polydimethylsiloxane-sealed semi-square ring resonator

•The results show a sharp Fano resonance curves displays in the spectrum and the values of H and ΔW have different effects on the Q factor and sensitivity.•Investigation indicated that the sensor is capable of thermal sensing with an outstanding sensitivity, as high as −4 nm/°C.•The sensor can offer a solution for the high sensitivity application of temperature monitoring. A compact Fano resonance temperature sensor is proposed in this paper. The sensor consists of two metal-insulator-metal (MIM) waveguides and a side-coupled polydimethylsiloxane (PDMS)-sealed semi-square ring resonator. We numerically investigate the transmission characteristics of the plasmonic structure to assess the optical properties of the sensor with the finite element method (FEM) and obtained great optical performance. The simulation results show that a sharp transmission-reflection profile can be observed in the transmission spectra and the Fano resonances curves exhibit different responses to the variations of structural parameters and ambient temperature. Due to the high thermal-optic coefficient of PDMS, the proposed sensor has an outstanding sensitivity, as high as −4 nm/°C. Our research also demonstrates that the device has the advantage of low dissipation loss due to the high Q factor. The sensor offers the prospect of development of practical applications for high sensitivity temperature-measurement.