Visible Wavelength Flatband in a Gallium Phosphide Metasurface

TL;DR

This paper demonstrates a gallium phosphide metasurface with a flat photonic band at visible wavelengths, enhancing light-matter interactions and enabling advanced photonic applications.

Contribution

It introduces the first experimental realization of a flatband in a visible-wavelength metasurface using gallium phosphide, with integration of quantum emitters.

Findings

Flatband observed at ~580 nm over 10° half-angle.

Successful integration of cadmium selenide nanoplatelets with enhanced photoluminescence.

Potential for applications in nonlinear imaging and topological photonics.

Abstract

Engineering the dispersion of light in a metasurface allows for controlling the light-matter interaction strength between light confined in the metasurface and materials placed within its near-field. Specifically, engineering a flatband dispersion increases the photonic density of states thereby enhancing the light-matter interaction. Here, we experimentally demonstrate a metasurface with a flat dispersion at visible wavelengths. We designed and fabricated a suspended one-dimensional gallium phosphide metasurface and measured the photonic band structure via energy-momentum spectroscopy, observing a photonic band that is flat over $10^o$ of half-angle at $\sim 580$nm. We integrated cadmium selenide nanoplatelets with the metasurface, and measured coupled photoluminescence into the flatband. Our demonstration of a photonic flatband will enable the possibility of integrating emerging quantum emitters to the metasurface with possible applications in nonlinear image processing, and topological photonics.