Design of a plasmonic refractive index sensor based on the amplifier system with two plasmonic waveguides and four cavities with different dimensions and coordinates

In this research, we design a plasmonic refractive index sensor based on metal insulated metal waveguide (MIM) and examine it numerically. To design the structure of this sensor, we use five cavities with different dimensions and coordinates and two plasmonic waveguides. The resonant wavelengths and refractive index of the resonators are investigated and simulated by the finite difference time domain (FDTD) method. Due to the fact that the sensors and conduction characteristics of plasmonic waves are affected by the structure parameters, by changing the refractive index and changing the dimensions of the cavities, we can weaken or strengthen the passage coefficient in the resonant modes. As a result, we obtain the sensitivity coefficient, the competency digit (FOM) and the sensor quality coefficient. These plasmonic sensors with a simple frame and high optical resolution can be used to measure the refractive index in the medical, chemical and food industries, and due to the special correct distribution of resonances, they are highly sensitive to changes in the refractive index of the environment.