Phase diagram to design passive nanostructures

TL;DR

This paper introduces a universal phase diagram for passive scatterers that maps electromagnetic properties, revealing physical bounds and enabling systematic design of nanostructures with diverse scattering phenomena.

Contribution

It presents a novel phase diagram framework that unifies various scattering phenomena and offers a systematic method for designing passive nanostructures based on phase trajectories.

Findings

Revealed physical bounds based on power conservation.

Illustrated diverse phenomena like cloaking and superscattering.

Demonstrated design method using core-shell scatterers.

Abstract

A phase diagram, defined by the amplitude square and phase of scattering coefficients for absorption cross-section in each individual channel, is introduced as a universal map on the electromagnetic properties for passive scatterers. General physical bounds are naturally revealed based on the intrinsic power conservation in a passive scattering system, entailing power competitions among scattering, absorption, and extinction. Exotic scattering and absorption phenomena, from resonant scattering, invisible cloaking, coherent perfect absorber, and subwavelength superscattering can all be illustrated in this phase diagram. With electrically small core-shell scatterers as an example, we demonstrate a systematic method to design field-controllable structures based on the allowed trajectories in the phase diagram. The proposed phase diagram not only provides a simple tool to design optical devices but also promotes a deep understanding on Mie's scattering theory.