Near-perfect microlenses based on graphene microbubbles

Microbubbles acting as lenses are interesting for optical and photonic applications such as volumetric displays,optical resonators,integration of photonic components onto chips,high-resolution spectroscopy,lithography,and imaging.However,stable,rationally designed,and uniform microbubbles on substrates such as silicon chips are challenging because of the random nature of microbubble formation.We describe the fabrication of elastic microbubbles with a precise control of volume and curvature based on femtosecond laser irradiated graphene oxide.We demonstrate that the graphene microbubbles possess a near-perfect curvature that allows them to function as reflective microlenses for focusing broadband white light into an ultrahigh aspect ratio diffraction-limited photonic jet without chromatic aberration.Our results provide a pathway for integration of graphene microbubbles as lenses for nanophotonic components for miniaturized lab-on-a-chip devices along with applications in high-resolution spectroscopy and imaging.