Pressure and temperature dual-parameter optical sensor based on the MIM waveguide structure coupled with two T-shaped cavities

This paper elaborates on the design and simulation of a multifunctional optical sensor that features simultaneous detection of pressure and temperature, which is based on the metal–insulator–metal waveguide structure with two T-shaped resonant cavities. Depending on the simulation findings, pressure and temperature can be measured separately by two T-shaped cavities at different Fano resonance wavelengths. As the pressure applied to the upper T-shaped cavity increases, the resonance wavelength first shifts linearly due to the slight deformation of the cavity, and the maximum pressure sensitivity reaches 12.48 nm/MPa. After the pressure exceeds a threshold, the relationship between pressure and resonance wavelength transforms into a quadratic polynomial. In the lower T-shaped cavity, solid polydimethylsiloxane is sealed as a thermal-sensitive material, effectively preventing material overflow brought on by structural micro-vibration under pressure, and its high thermo-optical coefficient prompts a temperature sensitivity of 0.36 nm/°C. Furthermore, by optimizing the choice of Fano resonances, pressure and temperature can be sensed independently without mutual interference. The designed sensor provides extensive application possibilities for scenarios where multiparameter monitoring is required.