Tunneling inhibition for subwavelength light

TL;DR

This paper demonstrates that dynamically modulated waveguide arrays can inhibit light tunneling at subwavelength scales, enabling undistorted propagation of tiny light spots over long distances, with potential applications in nanophotonics.

Contribution

It introduces a method to suppress light tunneling in subwavelength waveguide arrays using specific refractive index modulations, including dielectric and metallic structures.

Findings

Tunneling can be suppressed at specific modulation frequencies.

Subwavelength light spots propagate undistorted over hundreds of Rayleigh lengths.

Nonlinearity enhances localization of light.

Abstract

We show that light tunneling inhibition may take place in suitable dynamically modulated waveguide arrays for light spots whose features are remarkably smaller than the wavelength of light. We found that tunneling between neighboring waveguides can be suppressed for specific frequencies of the out-of-phase refractive index modulation, affording undistorted propagation of the input subwavelength light spots over hundreds of Rayleigh lengths. Tunneling inhibition turns out to be effective only when the waveguide separation in the array is above a critical threshold. Inclusion of a weak focusing nonlinearity is shown to improve localization. We analyze the phenomenon in purely dielectric structures and also in arrays containing periodically spaced metallic layers.