Controllable coherent perfect absorption in a composite film

TL;DR

This paper demonstrates how metal-dielectric composite slabs can achieve controllable coherent perfect absorption at multiple frequencies, highlighting the role of absorption and geometrical parameters in optimizing CPA.

Contribution

It introduces a method to control CPA in composite films and explores CPA at multiple frequencies, advancing the understanding of absorption in heterogeneous media.

Findings

CPA can be controlled by geometrical parameters.

Simultaneous CPA at two distinct frequencies is achievable.

Absorption is essential for CPA to occur.

Abstract

We exploit the versatility provided by metal--dielectric composites to demonstrate controllable coherent perfect absorption (CPA) in a slab of heterogeneous medium. The slab is illuminated by coherent light from both sides, at the same angle of incidence and the conditions required for CPA are investigated as a function of the different geometrical parameters. The simultaneous realization of CPA at two distinct frequencies is also shown. Finally, our calculations clearly elucidate the role of absorption as a necessary prerequisite for CPA.