Singular evanescent wave resonances

TL;DR

This paper reveals a novel type of resonance in moving metallic Fabry-Perot plates where evanescent waves enable perfect phase and amplitude balance, overcoming material absorption and non-ideal reflectivities, driven by mechanical energy conversion.

Contribution

It introduces the concept of singular evanescent wave resonances in moving media, demonstrating perfect resonance conditions despite losses, and explores their potential for enhancing non-equilibrium phenomena.

Findings

Evanescent waves enable perfect phase and amplitude balance in moving resonators.

Resonance occurs only when metallic plates are in relative motion at a critical distance.

Energy for resonance is derived from mechanical motion, similar to optical gain in lasing.

Abstract

Resonators fold the path of light by reflections leading to a phase balance and thus constructive addition of propagating waves. However, amplitude decrease of these waves due to incomplete reflection or material absorption leads to a finite quality factor of all resonances. Here we report on our discovery that evanescent waves can lead to a perfect phase and amplitude balance causing an ideal Fabry-Perot resonance condition in spite of material absorption and non-ideal reflectivities. This counterintuitive resonance occurs if and only if the metallic Fabry-Perot plates are in relative motion to each other separated by a critical distance. We show that the energy needed to approach the resonance arises from the conversion of the mechanical energy of motion to electromagnetic energy. The phenomenon is similar to lasing where the losses in the cavity resonance are exactly compensated by optical gain media instead of mechanical motion. Nonlinearities and non-localities in material response will inevitably curtail any singularities however we show the giant enhancement in non-equilibrium phenomena due to such resonances in moving media.