Figure of merit and sensitivity enhancement of biosensor LSPR in investigated for visible and near infrared

We have proposed new localized surface plasmon (LSP) hybrid nanostructures, based on gold nanowires form T (AuNWs-T) deposited on a glass substrate (substrate/AuNWs) or on a graphene-coated Au film (substrate/Au film/graphene/AuNWs). The results have shown that by optimizing the parameters of nanoplasmonic structures and the incidence angle of the excitation wave. This study gives an ultra-detection performance. The detection performance parameters expressed in terms of figure of Merit (FoM) and sensitivity are improved to more than 593% (7 times) for FoM and 284.86% (3.85 times) the sensitivity compared to a traditional AuNWs-based LSPR nanostructure in normal incidence. Due to the improvement of localized surface plasmon resonance (LSPR) which is attributed to the effect of coupling between the AuNWs-T and graphene-coated Au film. This complicated nanoplasmonic resonance LSPR enhancement with the incident angle, especially in the presence of gold nanowires, can be controlled reliably by engineering the dispersion curve. These results are followed by an enhancement of the calculated electric field strength along several cut lines through the hybrid nanostructures. Our results show that the hybrid nanostructures devices hold great promise as biosensors for different types of analytes and for optical nanotechnologies. • We proposed a hybrid nanostructures Substrate/Au-film/Graphene/AuNWs as a high performance refractive index biosensor. • Improved figure of merit (FoM) and sensitivity are used to characterize the biosensing performance in visible and near infrared. • The FoM and sensitivity enhancement of biosensor was 593% and 284.86%, respectively. • High sensitivity 946 nm/RIU can be achieved with AuNWs-T attached to graphene-coated Au film. • The optimal hybrid nanostructure of the biosensor was defined based on the terms FoM, sensitivity and electric field.