Superfocusing effect in the chain of silver nanorods

A chain of three silver nanorods with progressively decreasing sizes and separations is designed to focus the electric fields around the small nanorods. The optical properties of the chain of silver nanorods are investigated by the discrete dipole approximation method. The results show that, compared with the individual small nanorod and the chain of two nanorods, many enhanced electric fields are focused around the small nanorod of the chain of three nanorods due to the electric field couplings between adjacent nanorods. Therefore, the design of the chain of three nanorods provides a way to obtain stronger electric fields. In addition, how the structural parameters of the chain of three nanorods affect their optical properties is also studied.