Design of mid infrared high sensitive metal-insulator-metal plasmonic sensor

In this paper, high sensitivity plasmonic refractive index sensor based on implanted cavities in Metal-Insulator-Metal (MIM) waveguide is designed and analyzed using two dimensional (2D) FDTD algorithm with perfectly matched layer boundary conditions. The dimensions of the introduced single and double cavities with rectangular defect are analyzed and simulated for the best sensor performance. The results reveal in linear correlation between the resonance wavelengths of the proposed defected cavities and the refractive index of the material under testing which is placed in the active region of the sensor. Also, simulation results show that the sensor resolution of refractive index, which depends on wavelength resolution of the detection system, can reach as high as 3.84 x 10(-6) RIU, equivalentely to a sensitivity of 2602.5 nm/RIU, by taking the wavelength resolution of 0.01 nm.With the achieved optimum design by considering the tradeoff between the detected power, sensitivity and structure size, the transmittance level is enhanced by 118.08% compared to the first design. The proposed sensor can be used for different interesting applications such as identification of various materials including biosensor application, by proper design.