Band engineering method to create Dirac cones of accidental degeneracy in general photonic crystals without symmetry.

@article{Chu2021BandEM,
  title={Band engineering method to create Dirac cones of accidental degeneracy in general photonic crystals without symmetry.},
  author={Hongchen Chu and Yang Zhang and Jie Luo and Changqing Xu and Xiang Xiong and Ruwen Peng and Mu Wang and Yun Lai},
  journal={Optics express},
  year={2021},
  volume={29 12},
  pages={
          18070-18080
        }
}
Symmetry usually plays a key role in the formation of the Dirac cone in the band structure of triangular or hexagonal systems. In this work, we demonstrate a systematic method to create Dirac cones of accidental degeneracy in general photonic crystals without symmetry. With this method, a band gap can be closed gradually through a series of modification to the unit structure based on the eigenfields of the band edges, and consequently a Dirac point is formed with Dirac conical dispersions in… 
Hermitian and Non-Hermitian Dirac-Like Cones in Photonic and Phononic Structures
Accidental degeneracy plays an important role in the generation of novel band dispersions. Photonic structures that exhibit an accidental Dirac-like conical dispersion at the center of the Brillouin

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