Coherent perfect absorption in resonant materials

TL;DR

This paper demonstrates broadband coherent perfect absorption in a polymer film with organic dye, enabling full absorption over a 60 nm range by designing a spectral cavity, independent of the dye's intrinsic absorption levels.

Contribution

It introduces a method to achieve broadband CPA in resonant materials using a spectral cavity, overcoming limitations of narrow bandwidths and high doping quenching.

Findings

Achieved CPA over ~60 nm bandwidth in a polymer film.

Designed a planar cavity with a spectral dip matching dye linewidth.

Enabled strong absorption in laser dyes regardless of intrinsic absorption levels.

Abstract

Coherent perfect absorption (CPA) is an interferometric effect that guarantees full absorption in a lossy layer independently of its intrinsic losses. To date, it has been observed only at a single wavelength or narrow bandwidths, whereupon wavelength-dependent absorption can be ignored. Here we produce CPA over a bandwidth of ~ 60 nm in a 2-um-thick polymer film with a low-doping concentration of an organic laser dye. A planar cavity is designed with a spectral `dip' to accommodate the dye resonant linewidth, and CPA is thus achieved even at its absorption edges. This approach allows realizing strong absorption in laser dyes - and resonant materials in general - independently of the intrinsic absorption levels, with a at spectral profile and without suffering absorption quenching due to high doping levels.