Confining Light in Deep Subwavelength Electromagnetic Cavities

TL;DR

This paper demonstrates the theoretical possibility of confining electromagnetic waves in extremely small cavities using transformation optics, revealing modes with unique properties suitable for optical data storage and quantum applications.

Contribution

It introduces a new class of deep subwavelength electromagnetic cavities with continuous spectra and high quality factors, resilient to material imperfections.

Findings

Existence of arbitrarily small perfect cavities with confined modes

Absence of bending losses in these cavities

High-Q subwavelength cavities resilient to material losses

Abstract

We demonstrate that it is possible to confine electromagnetic radiation in cavities that are significantly smaller than the wavelength of the radiation it encapsulates. To this aim, we use the techniques of transformation optics. First, we present a "perfect cavity" of arbitrarily small size in which such confined modes can exist. Furthermore, we show that these eigenmodes have a continuous spectrum and that bending losses are absent, in contrast to what is observed in traditional microcavities. Finally, we introduce an alternative cavity configuration that is less sensitive to material imperfections and still exhibits deep subwavelength modes combined with high quality factor, even if considerable material losses are included. Such a cavity may be interesting for the storage of information in optical data processing and for applications in quantum optics.