Broadband superoscillation brings a wave into perfect three-dimensional focus

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Article number075148
Journal / PublicationPhysical Review B
Volume95
Issue number7
Publication statusPublished - 15 Feb 2017
Externally publishedYes

Abstract

The fundamental properties of a wave precludes it from being localized to subwavelength distances in all dimensions of the wave's existence. The inability to focus electromagnetic waves to an all-direction subwavelength spot limits the 3D resolution of a conventional imaging system to about half the imaging wavelength. A plethora of super-resolution imaging systems have been designed which obtain super-resolution in one or two (but not all) dimensions, but they suffer various restrictions in working distance and the classes of objects they can image. In this paper, we report a first investigation into a wave that is focused to subwavelength dimensions in all directions. After reviewing the physics of wave dispersion and diffraction which seemingly preclude this phenomenon, we sidestep these preclusions using a broadband superoscillation waveform and synthesize an all-direction subwavelength focus. We report the salient spatial and temporal features of this wave, and apply it to achieve 3D super-resolution imaging.