Subwavelength dynamic focusing in plasmonic nanostructures using time reversal

Abstract

We employ time reversal for deep subwavelength focusing in plasmonic periodic nanostructures. The strong anisotropy enables propagating modes with very large transverse wave vector and moderate propagation constant, facilitating transformation of diffraction-limited plane waves to high-$K$ Bloch waves in the plasmonic nanostructure. Time reversal is used to excite the waves in the nanostructure at the exact amplitude and phase to focus the incident light to dimensions well below the diffraction limit at any point in the structure, exemplifying a true subdiffractional confinement and resolution.