CPA-Lasing in Thin-Elastic Plates via Exceptional Points

TL;DR

This paper demonstrates how parity-time symmetry breaking in elastic plates enables a coherent perfect absorber-laser (CPAL) that can amplify, detect tiny vibrations, and harvest energy, with potential applications in nanoscience and geophysics.

Contribution

It introduces the concept of CPAL in elastic plates using $ ext{PT}$-symmetry, expanding the application of such devices beyond optics to flexural waves.

Findings

CPAL can be realized in elastic plates via $ ext{PT}$-symmetry.

The device can amplify or absorb flexural waves with low input energy.

Potential applications include nanoscale vibration detection and energy harvesting.

Abstract

We present here how a coherent perfect absorber-laser (CPAL) enabled by parity-time ($\mathcal{PT}$)-symmetry breaking may be exploited to build monochromatic amplifying devices for flexural waves. The fourth order partial differential equation governing the propagation of flexural waves leads to four by four transfer matrices, and this results in physical properties of the $\mathcal{PT}$-symmetry specific to elastic plate systems. We thus demonstrate the possibility of using CPAL for such systems and we argue the possibility of using this concept to detect extremely small-scale vibration perturbations with important outcomes in surface science (imaging of nanometer vibration) and geophysics (improving seismic sensors like velocimeters). The device can also generate finite signals using very low exciting intensities. The system can alternatively be used as a perfect absorber for flexural energy by tailoring the left and right incident wave for energy harvesting applications.