Ultralow-threshold laser using super-bound states in the continuum

Abstract

Wavelength-scale lasers provide promising applications through low power consumption requiring for optical cavities with increased quality factors. Cavity radiative losses can be suppressed strongly in the regime of optical bound states in the continuum; however, a finite size of the resonator limits the performance of bound states in the continuum as cavity modes for active nanophotonic devices. Here, we employ the concept of a supercavity mode created by merging symmetry-protected and accidental bound states in the continuum in the momentum space, and realize an efficient laser based on a finite-size cavity with a small footprint. We trace the evolution of lasing properties before and after the merging point by varying the lattice spacing, and we reveal this laser demonstrates the significantly reduced threshold, substantially increased quality factor, and shrunken far-field images. Our results provide a route for nanolasers with reduced out-of-plane losses in finite-size active nanodevices and improved lasing characteristics.

Nodal lines in momentum space: topological invariants and recent realizations in photonic and other systems

“…For photonic applications, high density of states of surface states in nodal lines systems [21,22] are expected to enhance spontaneous emission, resonant scattering, nonlinearities and blackbody radiation. The bound states in the continuum related to nodal lines [31] may find applications in lasing [188] and sensing [189]. Although direct applications seem limited for the moment, a better understanding of topological phases of nodal lines would give us rich knowledge and interesting physics of artificially designed materials system as well as electronic materials.…”

Electrically Pumped Lasing from Bound States in the Continuum

“…It comes from two main mechanisms: symmetry incompatibility, and destructive interference between the leaky channels 18,24 . Destructive interference can be described by the Friedrich-Wintgen theory 16 , spawning a supercavity mode of a subwavelength high-index dielectric resonator 25 , off-Γ BICs of plasmonic-photonic hybrid systems 26 , and a special type of nanolaser driven by merging symmetryprotected and accidental BICs 27 .…”

Analytical non-Hermitian description of Photonic Crystals with arbitrary Lateral and Transverse symmetry

“…They are topological charges pinned at polarization vortices in momentum space [14,15]. Topological manipulations (merging, splitting..) of BIC charges [16] propose unique way to modify farfield radiation [17], robustness [18] and threshold [19] of light emitting devices. The second one, EPs, where photonic complex resonances coalesce, are degeneracy points of non-Hermitian physics [20].…”