Nanorefractive index transducer using a ring cavity with an internal h-shaped cavity grounded on Fano resonance.

Building on the Fano resonance observation, a new refractive index transducer structure at the nanoscale is proposed in this article, which is a refractive index transducer consisting of a metal-insulator-metal (MIM) waveguide structure coupled with a ring cavity internally connected to an h-shaped structure (RCIhS). Using an analytical method based on COMSOL software and finite element method (FEM), the effect of different geometric parameters of the structure on the trans-mission characteristics of the system is simulated and analyzed, which in turn illustrates the effect of the structural parameters on the output Fano curves. As simulation results show, the internally connected h-shaped structure is an influential component in the Fano resonance. By optimizing the geometrical parameters of the structure, the system finally accomplishes a sensitivity (S) of 2400 nm/RIU and a figure of merit (FOM) of 68.57. The sensor has also been demonstrated in the realm of temperature detection, having tremendous potential for utilization in future nano-sensing and optically integrated systems.