A High-Performance Plasmonic Nanosensor Based on an Elliptical Nanorod in an MIM Configuration

Abstract

In this paper, we propose and numerically investigate a surface plasmon resonance-based nanophotonic biosensor structure providing an extremely high sensitivity and transmission efficiency with a high figure-of-merit (FOM). The sensor structure consists of a 1-D metalic grating, rectangular nanoslabs, and single elliptical nanorod (NR) in a metal-insulator-metal configuration. The spectral response of the proposed sensor is evaluated numerically by using the finite-difference-time-domain computation method for its operation in the near-infrared region of the spectrum. The results show strong enhancement and very high spectral sensitivity of the local electromagnetic fields near the tip of the NR. The performance parameters of the nanosensor are then optimized as a function of the shape, size, cavity length, and other parameters of the nanostructures. The optimized sensitivity of this device is found to be 1960 nm/RIU with a transmission efficiency of 82.30% and an FOM of 42.26, which are very promising as compared to those of the contemporary nanosensors. As a specific biosensing application, the proposed sensor device is numerically simulated with different concentrations of satellite tobacco mosaic virus (STMV) solutions and found to be capable of sensing the virus with extraordinary optical sensitivity up to 0.245 nm/(g/l) making the nanosensor sensitive even to the smallest of changes in concentrations of the STMV solutions. This highly sensitive nanosensor may have aspiring applications in biomedical and environmental sensing mechanisms and nanophotonic integrated circuits.