Dynamical Drexhage Effect: Amplified Emission in Time-Modulated Electromagnetic Environments

TL;DR

This paper explores how nonrelativistic motion near interfaces can dynamically amplify dipole emission through a time-modulated electromagnetic environment, extending the Drexhage effect.

Contribution

It introduces a dynamical extension of the Drexhage effect using macroscopic QED, showing how motion-induced modulation can amplify emission in nanophotonic systems.

Findings

Dipole emission can be amplified via motion-induced modulation.

Threshold modulation amplitudes depend on interface permittivities.

Amplification is possible near epsilon-near-zero materials.

Abstract

We investigate the effect of nonrelativistic motion on the emission dynamics of a dipole emitter moving next to a reflecting interface. Within the formalism of macroscopic QED, we obtain a general equation of motion for the dipole amplitude in terms of the dyadic Green's function, yielding a dynamical extension of the Drexhage effect. At short dipole-surface distances, the dipole can be described as a parametric oscillator featuring time-dependent dampings and Lamb shifts, both arising from the self-induced modulation of the surrounding electromagnetic environment. Importantly, these time-dependent parameters do not always average out, leading to amplification of the dipole amplitude and the radiated intensity when considering certain sinusoidal trajectories with specific modulation amplitudes and frequencies. We derive threshold modulation amplitudes as function of the relative permittivities at the interface. Qualitatively, in the vicinity of certain epsilon-near-zero materials, amplification is possible purely by modulation of the damping. Our findings open up avenues for the dynamic control of light-matter interaction in nanophotonic environments.