Refractive index and temperature sensing based on defect resonator coupled with a MIM waveguide

In this paper, a refractive index and temperature sensor based on Fano resonance is realized. The proposed structure is composed of a MIM waveguide and a defect cavity which is filled with sealed ethanol. The Fano spectra and field distribution is numerically investigated by the two-dimensional finite-difference time-domain (FDTD) method. Due to the symmetry breaking, the sharp and asymmetric transmission spectra can be used as a sensor with high sensitivity. The sensitivity of the proposed structure can be up to 652 nm/RIU and 0.225 nm/degrees C. Because of the high sensitivity, the proposed plasmonic structure may have potential application in nanosensing.