A refractive index sensor based on an analogy T shaped metal–insulator–metal waveguide

Abstract A refractive index sensor based on plasmonics metal–insulator–metal (MIM) waveguide coupled with an analogy T shaped resonator is proposed. The analogy T shaped resonator consists of two perpendicular rectangle cavities. At visible light range, the transmission characteristics of the sensor are investigated by using the finite-difference time-domain (FDTD) method. The transmission spectrum exhibits a Fano resonance shape, which is caused by the interaction between the broadband and narrowband resonances of the two rectangle cavities. The refractive index sensing property is systematically studied with varied structural parameters and refractive indices. The result shows the maximum sensitivity of the sensor is 680 nm/RIU. The sensor may be potential applied in integrated of optical circuits.