Anomalies in Light Scattering

TL;DR

This paper provides a unified theoretical framework for understanding exotic electromagnetic scattering phenomena by analyzing the poles and zeros of the scattering matrix, enabling tailored control of scattering behaviors.

Contribution

It introduces a unified description linking diverse anomalous scattering effects to the properties of scattering matrix poles and zeros.

Findings

All exotic scattering phenomena can be traced to poles and zeros of the scattering matrix.

Managing these poles and zeros allows for tailoring unusual scattering regimes.

The framework applies across the electromagnetic spectrum from radio to X-rays.

Abstract

Scattering of electromagnetic waves lies at the heart of most experimental techniques over nearly the entire electromagnetic spectrum, ranging from radio waves to optics and X-rays. Hence, deep insight into the basics of scattering theory and understanding the peculiar features of electromagnetic scattering is necessary for the correct interpretation of experimental data and an understanding of the underlying physics. Recently, a broad spectrum of exceptional scattering phenomena attainable in suitably engineered structures has been predicted and demonstrated. Examples include bound states in the continuum, exceptional points in PT-symmetrical non-Hermitian systems, coherent perfect absorption, virtual perfect absorption, nontrivial lasing, non-radiating sources, and others. In this paper, we establish a unified description of such exotic scattering phenomena and show that the origin of all these effects can be traced back to the properties of poles and zeros of the underlying scattering matrix. We provide insights on how managing these special points in the complex frequency plane provides a powerful approach to tailor unusual scattering regimes.