Degeneracy of cross sections in scattering of light

TL;DR

This paper proves that in light scattering by cylindrical passive objects, a unified energy diagram describes absorption, scattering, and extinction, revealing degeneracy where different systems share the same energy characteristics, aiding functional design.

Contribution

The work introduces a universal energy diagram for scattering systems, demonstrating degeneracy across different resonant orders and configurations, supported by theoretical and numerical analysis.

Findings

Energy diagram unifies absorption, scattering, and extinction cross sections.

Degeneracy allows different systems to have identical energy characteristics.

Supports design flexibility in energy harvesting, imaging, and sensing.

Abstract

We theoretically and numerically prove that under an electromagnetic plane wave with linear polarization incident normally to cylindrical passive scatterers, a single energy diagram can integrate absorption, scattering, and extinction cross sections for arbitrary scattering systems, irrespective of internal configuration, material parameters, and its sizes. For a system with definite resonant orders, along the corresponding boundary of the energy diagram, not only the magnitudes of scattering coefficients, but also its phases, are required the same, corresponding to superabsorption or superscattering. For systems composed by larger resonant orders, the domain of the energy diagram can completely cover systems with lower one. Hence, systems with different resonant orders can provide the same energy characteristics, reflecting the energy degenerate property in light scattering. This degeneracy may relax more degrees of freedom in functional designs, such as energy harvesting, imaging, sensing devices. We demonstrate various systems based on real materials to support this finding.