Measurement of mechanical deformations induced by enhanced electromagnetic stress on a parallel metallic-plate system

TL;DR

This study experimentally measures local mechanical strains caused by electromagnetic stress on a metallic resonant system, revealing sign-changing strain distributions and significant stress enhancement over radiation pressure.

Contribution

It provides the first detailed measurement of local strain distributions induced by electromagnetic stress on a resonant metallic system, confirming theoretical predictions.

Findings

Strain changes sign across the resonant unit.

Electromagnetic stress enhancement exceeds 600 times radiation pressure.

Local stress distribution matches theoretical models.

Abstract

We measured the electromagnetic stress-induced local strain distribution on a centimeter-sized parallel-plate metallic resonant unit illuminated with microwave. Using a fiber interferometer, we found that the strain changes sign across the resonant unit, in agreement with theoretical predictions that the attractive electric and repulsive magnetic forces act at different locations. The enhancement of the corresponding maximum local electromagnetic stress is stronger than the enhancement of the net force, reaching a factor of >600 compared to the ordinary radiation pressure.