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

摘要

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.

主权项

1. A surface-emitting laser comprising:
a gain medium to emit an electromagnetic wave; and a photonic crystal, electromagnetically coupled to the gain medium and having an energy band structure characterized by a Dirac point at or near a center of a Brillouin zone of the photonic crystal and at a frequency within a gain band of the gain medium, to support radiation of at least a portion of the energy in the electromagnetic wave in a direction substantially orthogonal to a plane of the photonic crystal.