Visible Wavelength Flatband in a Gallium Phosphide Metasurface

Abstract

Engineeringthe dispersion of light in a metasurface allows forcontrolling the light-matter interaction strength between lightconfined in the metasurface and materials placed within its near-field.Specifically, engineering a flatband dispersion increases the photonicdensity of states, thereby enhancing the light-matter interaction.Here, we experimentally demonstrate a metasurface with a flat dispersionat visible wavelengths. We designed and fabricated a suspended one-dimensionalgallium phosphide metasurface and measured the photonic band structurevia energy-momentum spectroscopy, observing a photonic band that isflat over 10 & DEG; of half angle at & SIM;590 nm. We integratedcadmium selenide nanoplatelets with the metasurface and measured coupledphotoluminescence into the flatband. Our demonstration of a photonicflatband enables the possibility of integrating emerging quantum emittersto the metasurface with possible applications in nonlinear image processingand topological photonics.