The sensing characteristics of plasmonic waveguide with a single defect

A novel two-dimensional nanoscale structure for sensing which consists of a metal–insulator–metal (MIM) waveguide with a defect, is designed and numerically simulated by using the finite element method (FEM). Both of the refractive index sensing characteristics and the temperature sensing characteristics of the structure are analyzed systematically by investigating the transmission spectrum. The numerically simulated results show that the dip positions of the transmission spectrum have linear relationships with the refractive index of the material under sensing and the ambient temperature, respectively. Based on the relationships, the refractive index of the material under sensing or the ambient temperature can be obtained from the dip wavelength shift detection. When the width and the height of the defect are set to be 50 nm, 300 nm, respectively, the refractive index sensitivity can be obtained as high as 1736 nm RIU−1 and the temperature sensitivity is about 0.51 nm/°C with a FOM of 9.79. This work has a certain significance for designing nanoscale refractive index sensors and temperature sensors.