Controlling the interactions of surface plasmon polaritons generated by two-nanoslit structures for producing diverse sub-diffraction-limited patterns

Abstract

Flexible manipulation of surface plasmon polaritons (SPPs) in a small target area is very important for building functional plasmonic nanostructures. Here, we propose a second-order interference model to describe the interaction of SPPs generated between two nanoslits of a metal film, and propose a first-order interference model to describe the interaction of SPPs generated on each side of the two nanoslits. Using these models, a functional two-nanoslit unit structure that is capable of enhancing the peak intensities of SPPs between its two slits and diminishing the total intensity of SPPs on each side of its two slits can be designed, and another functional two-nanoslit unit structure that is capable of diminishing the peak intensities of SPPs between its two slits and enhancing the total intensity of SPPs on each side of its two slits can be designed too. In addition, the proposed models predicts that it is possible to design the mask that is capable of producing a complex pattern composed of multiple desired nanopatterns by combining multiple designed functional two-nanoslit unit structures together. Moreover, we numerically demonstrated that at the illumination wavelength of 405 nm, some complex patterns with a half-pitch resolution of about 56 nm, such as a superperiodic pattern and some letter-shaped patterns, can be produced in the photoresist by the masks designed using the proposed models.