Fig. 1: Single-photon emitter in the bound-state-in-the-continuum cavity.
From: Room-temperature strong coupling in a single-photon emitter-metasurface system
a Illustration of coupling between a single-photon emitter (SPE) and a bound-state-in-the-continuum (BIC) cavity with quality factor \(Q\). The BIC mode is formed by an array of vertical magnetic dipoles (pink arrows), which associates with an electric-field (blue doughnuts) circulating in the x-y plane (red arrows). An SPE with a horizontal transition dipole moment (yellow sphere with green arrow) spatially overlaps with the electric-field hotspots. For strong coupling, the theoretical condition \(g\ge |{\kappa }_{{{{{{\rm{cav}}}}}}}-{\kappa }_{{{{{{\rm{SPE}}}}}}}|/2\) has to be satisfied, where \(g\) is the coupling strength, \({\kappa }_{{{{{{\rm{cav}}}}}}}\) and \({\kappa }_{{{{{{\rm{SPE}}}}}}}\) are dissipative decay rates of the cavity and the emitter, respectively. b 30° tilted scanning electron microscope (SEM) image of the fabricated TiO2 nanopillar array (diameter \(\sim\) 260 nm, gap \(\sim\)4 nm). c SEM image of the array after transferring a 3-nm thick hexagonal boron nitride (hBN) film on top. Scale bars in (b) and (c) are 200 nm.
