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Double Dirac cones in two-dimensional dielectric photonic crystals
Optics Express
|May 14, 2015
Summary
Researchers demonstrate a double Dirac cone in a 2D dielectric photonic crystal (PC) by exploiting mode degeneracy. This unique structure exhibits a zero effective refractive index, enabling novel optical phenomena.
Area of Science:
- Condensed Matter Physics
- Photonics
- Materials Science
Background:
- Photonic crystals (PCs) offer unique control over light propagation.
- Dirac cones in PCs are crucial for phenomena like topological insulators and zero-refractive-index materials.
- Exploiting mode degeneracy is a promising avenue for designing novel PC functionalities.
Purpose of the Study:
- To investigate the possibility of achieving a double Dirac cone dispersion relation in a 2D dielectric photonic crystal.
- To analyze the properties and formation mechanism of the double Dirac cone.
- To explore the potential applications of such a structure, particularly its effective refractive index.
Main Methods:
- Utilizing the accidental degeneracy of doubly-degenerate dipolar and quadrupolar modes.
- Applying perturbation methods and group theory to analyze the band structure.
- Performing numerical simulations, including wave-front shaping, unidirectional transmission, and perfect tunneling.
Main Results:
- A double Dirac cone dispersion relation was successfully achieved at the Γ point in a 2D dielectric PC.
- The double cone was shown to consist of two identical, overlapping Dirac cones with predictable linear slopes.
- The linearity of the dispersion was confirmed to be guaranteed by the spatial symmetry of Bloch eigenstates.
- Numerical simulations indicated that the PC structure exhibits a zero effective refractive index.
Conclusions:
- The accidental degeneracy of specific modes provides a viable route to engineer double Dirac cones in 2D dielectric PCs.
- The demonstrated double Dirac cone structure possesses a zero effective refractive index, opening possibilities for advanced photonic devices.
- The findings contribute to the understanding of band structure engineering in photonic crystals and their potential applications in optics and electronics.
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