Nanoillumination based on self-focus and field enhancement inside a subwavelength metallic structure

Abstract

A subwavelength metallic structure is proposed to generate superstrong nanoillumination. Its attractive features are presented numerically with finite-difference time-domain method. By combining a subwavelength slit and a nanohole together into metallic screen, the light illuminated on the surface of the screen is firstly squeezed into the subwavelength slit with the aid of the generated surface plasmon, and then during propagation to the exit end of the slit, the light is focused on a nanohole fabricated at the bottom of the slit due to the self-imaging effect and is further enhanced by the transmission resonance when passing through the nanohole. Because of these three successive enhancement processes, the light from the nanohole could become thousand times stronger than the incident light and accordingly could have great potentials for applications in optical data storage, super-resolution imaging, lithography, photonics, and other applications that need nanoillumination. © 2007 American Institute of Physics.