Topological ring-cavity laser formed by honeycomb photonic crystals

We clarify theoretically that the topological ring-cavity (TRC) modes propagating along the interface between two honeycomb-type photonic crystals distinct in topology can be exploited for achieving stable single-mode lasing, with the maximal intensity larger than a whispering-gallery-mode counterpart by order of magnitude. Especially, we show that the TRC modes located at the bulk band-gap center benefit maximally from the gain profile since they are most concentrated and uniform along the interface, and that, inheriting from the Dirac-like dispersion of topological interface states, they are separated in frequency from each other and from other photonic modes, both favoring intrinsically single-mode lasing. A TRC mode running in a specific direction with desired orbital angular momentum can be stimulated selectively by injecting a circularly polarized beam. With the scheme proposed in the present work one can fabricate a topological laser of tens of micrometers in linear size by means of advanced semiconductor nanotechnologies, which generates chiral laser beams ideal for novel photonic functions.

Automated summary

Theoretical analysis shows that topological ring-cavity (TRC) modes can be used for stable single-mode lasing, with significantly higher intensity compared to other modes. By injecting circularly polarized beams, specific TRC modes with desired orbital angular momentum can be selectively stimulated. Advanced semiconductor nanotechnologies can be utilized to fabricate topological lasers generating chiral laser beams ideal for novel photonic functions.