Frequency-independent effective rest mass of photons in the 2TDLM model

TL;DR

This paper introduces a frequency-independent effective rest mass for photons in electromagnetic media, which can be derived from the refractive index, and demonstrates this concept using the 2TDLM model.

Contribution

It defines a novel frequency-independent photon rest mass and shows how to extract it from the refractive index in the 2TDLM model.

Findings

Effective rest mass can be obtained from the refractive index squared.

The method is demonstrated using the 2TDLM model.

Discussion on the relation between rest mass and electromagnetic parameters.

Abstract

A physically interesting {\it effective rest mass} of photons in electromagnetic media, which is independent of wave frequency $\omega$, is defined in the present paper. It is verified that this frequency-independent effective rest mass of photons can be easily read off from the optical refractive index squared $n^{2}(\omega) $ of commonly-seen electromagnetic media. As an illustrative example, we extract the frequency-independent effective rest mass of photons from $n^{2}(\omega) $ in the {\it two time derivative Lorentz material} (2TDLM) model. The connection between effective rest mass and electromagnetic parameters of electric permittivity ($\epsilon $) and magnetic permeability ($\mu $) in left-handed media is also briefly discussed.