Leveraging beam deformation to improve the detection of resonances

TL;DR

This paper demonstrates that under specific conditions, beam reflection from multilayered resonant structures can produce a narrower reflected beam, enhancing sensor resolution by leveraging a narrow angular resonance effect.

Contribution

It introduces theoretical tools and physical insights showing that beam narrowing near resonances can improve sensor resolution, a novel approach in resonance detection.

Findings

Reflected beam can be 10% narrower than incident beam near resonance

Sensor resolution can be improved by a factor of three using this effect

The phenomenon may occur in other physics domains with temporal wavepackets

Abstract

Decades of work on beam deformation on reflection, and especially on lateral shifts, have spread the idea that a reflected beam is larger than the incident beam. However, when the right conditions are met, a beam reflected by a multilayered resonant structure can be 10\% narrower than the incoming beam. Such an easily measurable change occurs on a very narrow angular range close to a resonance, which can be leveraged to improve the resolution of sensors based on the detection of surface plasmon resonances by a factor three. We provide theoretical tools to deal with this effect, and a thorough physical discussion that leads to expect similar phenomenon to occur for temporal wavepackets and in other domains of physics.