Non‐Hermitian Photonic Modes with Dual Skewness: Oblique Localization and Asymmetric Profile

ABSTRACT Light manipulation enabled by metamaterials and photonic crystals relies on diverse physical mechanisms to expand functionality. Their inevitable open characteristics introduce non‐Hermitian physics as another ingredient, and the higher‐dimensional non‐Hermitian skin effect offers a myriad of features for harnessing light. In this work, we utilize geometry as another degree of freedom in non‐Hermitian metamaterials to realize the dual skewness photonic mode (DSPM), characterized by oblique localization and asymmetric profiles. The criteria for achieving DSPMs in reciprocal non‐Hermitian metamaterials include anisotropic and complex dielectric tensors, as well as mismatched optical axes and geometric structures, which have been demonstrated numerically through various indicators. A photonic crystal design based on realistic parameters is proposed, and we validate that the DSPM is dynamically accessible. By solving the eigenstate, we further reveal that DPSM is governed by a generalized Fermi surface whose dimensionality exceeds that of the Fermi surface. Our results establish DSPMs as a platform for controllable quasi‐long‐range light interactions, while the geometry‐driven design principle provides a versatile route to extend higher‐dimensional non‐Hermitian physics to 3D architectures, synthetic dimensions, and other classical wave systems, opening new avenues for non‐Hermitian photonics.