High-Order Perfect Absorption in the Absence of Exceptional Point

TL;DR

This paper introduces a novel high-order perfect absorber that operates without relying on exceptional points, using delay-induced momentum-sensitive interference for enhanced wave control.

Contribution

It presents a general scattering framework enabling high-order perfect absorption without exceptional points by utilizing asynchronous coherent input and delay-induced phase control.

Findings

Achieves high-order perfect absorption without exceptional points.

Uses delay-induced phase control for momentum-sensitive interference.

Shows significant response to delay perturbations.

Abstract

High-order perfect absorption of coherent input has recently attracted significant attention due to its broadband absorption capacity. However, the realization of a high-order perfect absorber relies on the exceptional point (EP) to coalesce the scattering zeros. Here, we present a general scattering framework and achieve the high-order perfect absorber in the absence of EP. We consider the asynchronous coherent input, where a spatial delay introduces a momentum-dependent phase factor beyond the amplitude and phase control in synchronous coherent input. This new degree of freedom enables active control of the momentum dependent output, effectively reshaping the absorption line shape necessary for the high-order perfect absorber. Remarkably, despite the absence of EP, the proposed high-order perfect absorber exhibits significant response to the perturbations in the delay length. Our findings provide insights for the delay induced momentum-sensitive interference phenomenon and offer a new route for wave control.