Showing papers by "Ling Lu published in 2013"

Weyl points and line nodes in gyroid photonic crystals

Abstract: Materials exhibiting three-dimensional (3D) linear dispersion relations between frequency and wavevector are expected to display a wide range of interesting phenomena. 3D linear point degeneracies between two bands (“Weyl points”) have yet to be observed. Based on analytical and numerical analysis, researchers predict Weyl point formation in 3D photonic crystals.

Photonic crystal surface-emitting lasers enabled by an accidental Dirac point

Abstract: A photonic-crystal surface-emitting laser (PCSEL) includes a gain medium electromagnetically coupled to a photonic crystal whose energy band structure exhibits a Dirac cone of linear dispersion at the center of the photonic crystal's Brillouin zone. This Dirac cone's vertex is called a Dirac point; because it is at the Brillouin zone center, it is called an accidental Dirac point. Tuning the photonic crystal's band structure (e.g., by changing the photonic crystal's dimensions or refractive index) to exhibit an accidental Dirac point increases the photonic crystal's mode spacing by orders of magnitudes and reduces or eliminates the photonic crystal's distributed in-plane feedback. Thus, the photonic crystal can act as a resonator that supports single-mode output from the PCSEL over a larger area than is possible with conventional PCSELs, which have quadratic band edge dispersion. Because output power generally scales with output area, this increase in output area results in higher possible output powers.

Weyl points and line nodes in 3D photonic crystals

Abstract: We present theoretical discoveries of frequency-isolated Weyl points and line nodes, 3D linear point- and line-degeneracies, in gyroid photonic crystals. The associated surface states exhibit topological-protection and flat bands realizable from microwave to optical frequencies.