Electromagnetic energy and negative asymmetry parameter in coated magneto-optical cylinders: Applications to tunable light transport in disordered systems

TL;DR

This paper explores how external magnetic fields influence electromagnetic energy, scattering anisotropy, and light transport in coated magneto-optical cylinders, enabling tunable control over light behavior in disordered systems.

Contribution

It provides a new theoretical framework for controlling light scattering and energy storage in magneto-optical core-shell cylinders using magnetic fields and temperature.

Findings

Magnetic field reduces electromagnetic absorption in the terahertz range.

Scattering anisotropy can be tuned externally and reaches negative values.

Multiple light scattering properties can be controlled via magnetic field or temperature.

Abstract

We investigate electromagnetic scattering of normally irradiated gyrotropic, magneto-optical core-shell cylinders using Lorenz-Mie theory. A general expression for time-averaged electromagnetic energy inside a coated gyroelectric and gyromagnetic scatterer is derived. Using realistic material parameters for a silica core and InSb shell, we calculate the stored electromagnetic energy and the scattering anisotropy. We show that the application of an external magnetic field along the cylinder axis induces a drastic decrease in electromagnetic absorption in a frequency range in the terahertz, where absorption is maximal in the absence of the magnetic field. We demonstrate not only that the scattering anisotropy can be externally tuned by applying a magnetic field, but also that it reaches negative values in the terahertz range even in the dipolar regime. We also show that this preferential backscattering response results in an anomalous regime of multiple light scattering from a collection of magneto-optical core-shell cylinders, in which the extinction mean free path is longer than the transport mean free path. By additionally calculating the energy-transport velocity and diffusion coefficient, we demonstrate an unprecedented degree of external control of multiple light scattering, which can be achieved by either applying an external magnetic field or varying the temperature.