Abstract
We report numerically electromagnetic-induced transparency (EIT) and Fano resonances in simple plasmonic metasurfaces consisting of gold nanobars arranged in pi, H, and four-shaped fashion. The bright and dark elements in the metasurfaces are responsible for the emergence of EIT and Fano effects in the transmission spectrum. The concept of symmetry breaking is also introduced by incorporating multiple cavities in the metasurface, which relaxes the dipole coupling selection rules resulting in a mixture of dipole and higher order modes that interact and engenders EIT and Fano modes simultaneously in a nanostructure. Furthermore, the EIT and Fano resonances experience a significant red shift by increasing the refractive index of the background medium due to which high sensitivity of around 574 nmRIU
−1
, figure of merit of 32, and contrast ratio of 41% are realized. Moreover, the effective group index of the proposed metasurface is retrieved and is observed to be very high around the steep asymmetric Fano line shape and within the EIT window, signifying its potential use in slow light applications.