Transverse spin texture in optical non-Hermitian skin modes
Phys. Rev. A 114, 033522 – Published 21 September, 2026
DOI: https://doi.org/10.1103/64mw-c3ch
Abstract
In structured electromagnetic fields, polarization textures are often closely linked to the spatial variation of the energy flow. However, this familiar picture has been established mainly for lossless and isotropic settings, and concrete examples showing how it is modified in media with gain and loss remain limited. Here, we demonstrate that optical skin modes associated with the non-Hermitian skin effect carry a finite transverse circular-polarization texture, characterized by the third Stokes parameter as a descriptor of the local in-plane electric-field rotation. We further show that this electric-field spin texture deviates from the familiar lossless spin-flow picture. Using exact transverse electric mode solutions, we separate the common exponential skin envelope from the oscillatory component. This decomposition shows that the circular-polarization texture is not generated by the skin envelope itself but by the oscillatory interference component modified by non-Hermiticity. It also reveals a handedness bias and a reshaped spatial relation between circularity and intensity. Finite-element calculations confirm that these features remain robust in loss-biased anisotropic media. These results show that gain and loss provide additional freedom for engineering electric-field spin textures beyond conventional lossless photonic settings.