Analytical study of mode degeneracy in non-Hermitian photonic crystals with TM-like polarization
arXiv:1703.01832 · doi:10.1103/PhysRevB.96.075111
Abstract
We present an analytical study of the mode degeneracy in non-Hermitian photonic crystals (PC) with symmetry, from the perspective of the coupled-wave-theory (CWT). The wave couplings and leakages within the non-Hermitian PCs are depicted, and the condition of accidental triple degeneracy is derived which leads to a Dirac-cone like dispersion. We prove that, similar to the real Dirac-cone, the Dirac-cone like band in non-Hermitian PC possesses good linearity and isotropy in the vicinity of the point. Moreover, some topological transit of the band may occur when the parameters adiabatically evolve. However, the Berry phase remains zero at the point, indicated the Dirac-like-cone dosen't obey Dirac equation and it is only Dirac-cone.
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