Multi-Wavelength Achromatic Graphene Metalenses for Visible, NIR, and Beyond

Abstract

The demand for achromatic ultrathin flat lenses has become increasingly stringent, particularly for high-performance imaging and display applications. Despite significant progress in achromatic metasurface and diffraction lenses, no single material has yet been capable of constructing ultrathin achromatic flat lenses covering ultrabroad wavebands, including the visible and near-infrared (NIR), due to the limitations of material bandgaps. This limitation complicates fabrication processes, integration, and miniaturization, often leading to instability. In this paper, making use of the dispersionless nature of graphene, high numerical aperture multi-wavelength achromatic metalenses (MAGLs) made entirely from graphene is proposed and demonstrated. This approach, based on a partial intensity resonance (PIR) mechanism, requires no iterative algorithms. Two MAGLs for visible and communication bands, respectively, are designed and fabricated. Remarkably, the measured focal lengths only deviate by less than 0.15% from the desired values. The graphene metalens (GML) in the visible produced clear and high-quality images of microscopic character and Brassica napus cells. The demonstrated MAGLs significantly simplify the fabrication process and enhance integration, miniaturization, and stability. Their unique single-material design offers tremendous potential to replace conventional refractive lenses in applications such as virtual reality glasses, hyperspectral imaging systems, and fluorescence microscopes.