Plasmonic coupling dependent sensitivity in localized surface plasmon resonance based optical sensors

This paper investigates the impact of environmental changes on silver nanoparticles (AgNp) immobilized sensor probe within strong and weak plasmonic coupling regimes. To monitor these interaction regimes, evanescent wave absorption based on fiber optic and attenuated total reflection techniques have been employed. In the weak coupling regime, variations in refractive index (RI) primarily affect intensity rather than wavelength. Conversely, in the strong coupling regime, intensity decreases, while wavelength sensitivity increases with changes in RI. Our findings qualitatively agree with a theoretical framework based on the discrete dipole approximation (DDA) for two-particle interacting systems, providing valuable insights for optimizing plasmonic interactions to enhance sensitivity. This information will aid the scientific and industrial community in understanding the plasmonic interaction region for maximizing sensitivity of Localized surface plasmon resonance (LSPR) based photonic devices.