Interfacing single-photon emitters in atomically thin van der Waals crystals with photonic metasurfaces (Conference Presentation)

Abstract

One of the central challenges for practical applications of single-photon sources is the ability to efficiently extract light from a single quantum emitter. A useful single-photon source must emit into a well-defined direction because in practice one can collect light only in a finite solid angle. Here, we propose to harness the exceptional light molding capabilities of photonic metasurfaces to engineer the emission from quantum emitters and achieve highly directional emission. We have designed a phase gradient reflectarray metasurface, which efficiently collects spontaneous emission from a quantum emitter, located in the far-field (d~5 wavelengths), and redirects it back to the source. By controlling the phase imprinted by the metasurface on the incident light, we control the emission properties of the emitters. We apply this concept to design a metasurface for use with hexagonal boron nitride (hBN) single photon emitters operating at 620 nm. We have observed experimentally bright single photon emission at 620 nm with a remarkably narrow spectral width of zero-phonon line emission from multilayer hBN films synthesized by chemical vapor deposition. Simulations show that at a wavelength of 620 nm, the reflection efficiency of our metasurface is greater than 85%, and that the emission from these emitters are highly directional with deviation from emission in the surface-normal direction of 2∆θ ~ 20°. We will report on experimental measurements of hBN quantum emitters coupled to metasurfaces and describe metasurface designs for coupling of multiple quantum emitters.