Optical non-Hermitian skin effect in two-dimensional uniform media

The non-Hermitian skin effect (NHSE) is a localization phenomenon that occurs in certain non-Hermitian systems with gain and/or loss. Prior studies focused mainly on periodic structures, but the work asks whether NHSE can also appear in uniform (non-periodic) materials. The authors establish a theory for optical NHSE in non-Hermitian anisotropic media. They show that NHSE can occur in uniform media when the dielectric tensor has appropriate anisotropy and the material includes loss. They further state that the skin-mode localization is fully determined by an effective gauge potential arising from the anisotropy. Based on the theory, the authors propose subwavelength multilayer metamaterials as a platform to realize optical NHSE. They also introduce a concept of stationarily-excited skin modes where frequencies are forced to be real, and report that NHSE still occurs under this condition, suggesting observability under stationary excitation.