Comment on ‘No circular birefringence exists in a chiral medium: an analysis of single-mode refraction’

Abstract

Recent claims by Hu and Li (2023 New J. Phys. 25 023007) that isotropic chiral mediums do not exhibit circular birefringence, asserting that both mutually orthogonal circularly polarized states propagate at the same phase velocity, are refuted. We showcase that the analysis is flawed because it incorrectly interprets the eigenstates supported by reciprocal bi-isotropic mediums.