Analytical study of mode degeneracy in non-Hermitian photonic crystals with TM-like polarization

Article

关键词: SURFACE-EMITTING LASERS;    COUPLED-WAVE ANALYSIS;    TRANSVERSE-ELECTRIC POLARIZATION;    ZERO-INDEX METAMATERIALS;    DIRAC CONES;    TRANSMISSION;    LATTICE;    CHIP;    NANOCAVITY;    GUIDES;   

DOI  :  10.1103/PhysRevB.96.075111

来源: SCIE

【 摘 要 】

We present a study of the mode degeneracy in non-Hermitian photonic crystals (PC) with TM-like polarization and C-4v symmetry from the perspective of the coupled-wave theory (CWT). The CWT framework is extended to include TE-TM coupling terms which are critical for modeling the accidental triple degeneracy within non-Hermitian PC systems. We derive the analytical form of the wave function and the condition of Dirac-like-cone dispersion when radiation loss is relatively small. We find that, similar to a real Dirac cone, the Dirac-like cone in non-Hermitian PCs possesses good linearity and isotropy, even with a ring of exceptional points (EPs) inevitably existing in the vicinity of the second-order Gamma point. However, the Berry phase remains zero at the Gamma point, indicating the cone does not obey the Dirac equation and is only a Dirac-like cone. The topological modal interchange phenomenon and nonzero Berry phase of the EPs are also discussed.

【 授权许可】

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