Suppressing electromagnetic local density of states via slow light in lossy quasi-1d gratings

TL;DR

This paper introduces a spectral-averaging method to compute bandwidth-integrated LDOS, derives fundamental bounds on extinction, and demonstrates near-perfect LDOS suppression in lossy quasi-1D gratings by exploiting pseudogap edge states.

Contribution

It presents a novel spectral-averaging procedure for LDOS calculations, derives structure-agnostic bounds, and shows how pseudogap edge states can nearly suppress LDOS despite material losses.

Findings

Perfect LDOS suppression over finite bandwidth is impossible.

Pseudogap edge states can achieve near-perfect LDOS suppression.

Material dissipation influences the scaling of LDOS suppression.

Abstract

We propose a spectral-averaging procedure that enables computation of bandwidth-integrated local density of states (LDOS) from a single scattering calculation, and exploit it to investigate the minimum extinction achievable from dipolar sources over finite bandwidths in structured media. Structure-agnostic extinction bounds are derived, providing analytical insights into scaling laws and fundamental design tradeoffs with implications to bandwidth and material selection. We find that perfect LDOS suppression over a finite bandwidth $\Delta\omega$ is impossible. Inspired by limits which predict nontrivial $\sqrt{\Delta\omega}$ scaling in systems with material dissipation, we show that pseudogap edge states of quasi-1d bullseye gratings can -- by simultaneously minimizing material absorption and radiation -- yield arbitrarily close to perfect LDOS suppression in the limit of vanishing bandwidth.