When does the choice of the refractive index of a linear, homogeneous, isotropic, active, dielectric medium matter?

TL;DR

This paper examines the significance of choosing the correct refractive index in active dielectric media, highlighting its importance in half-space problems versus other scenarios like scattering and waveguides.

Contribution

It clarifies when the choice of refractive index affects solutions, emphasizing its importance in the half-space problem and less so in other typical applications.

Findings

Choice of refractive index is critical for half-space problems.

For scattering, waveguides, and lenses, either index choice yields valid solutions.

Correct index choice impacts the accuracy of certain electromagnetic analyses.

Abstract

Two choices are possible for the refractive index of a linear, homogeneous, isotropic, active, dielectric material. Either of the choices is adequate for obtaining frequency-domain solutions for (i) scattering by slabs, spheres, and other objects of bounded extent; (ii) guided-wave propagation in homogeneously filled, cross-sectionally uniform, straight waveguide sections with perfectly conducting walls; and (iii) image formation due to flat lenses. The correct choice does matter for the half-space problem, but that problem is not realistic.