Controlling light-with-light without nonlinearity

TL;DR

This paper demonstrates that two low-intensity coherent light beams can interact on a nanoscale metamaterial to modulate each other's intensity, enabling light control without nonlinear media.

Contribution

It introduces a method for controlling light with light using linear metamaterials, bypassing the need for nonlinear interactions at high intensities.

Findings

Beams can modulate each other's intensity on a nanoscale metamaterial.

Interference can eliminate plasmonic losses or cause near-total absorption.

Potential applications include ultrafast optical devices and filters.

Abstract

According to Huygens' superposition principle, light beams traveling in a linear medium will pass though one another without mutual disturbance. Indeed, it is widely held that controlling light signals with light requires intense laser fields to facilitate beam interactions in nonlinear media, where the superposition principle can be broken. We demonstrate here that two coherent beams of light of arbitrarily low intensity can interact on a metamaterial layer of nanoscale thickness in such a way that one beam modulates the intensity of the other. We show that the interference of beams can eliminate the plasmonic Joule losses of light energy in the metamaterial or, in contrast, can lead to almost total absorbtion of light. Applications of this phenomenon may lie in ultrafast all-optical pulse-recovery devices, coherence filters and THz-bandwidth light-by-light modulators.