Refractive and Meta-optics Hybrid System

Current metalenses with large numerical apertures suffer from low efficiency. In this paper, we demonstrate a refractive-meta hybrid system consisting of a ball lens mainly providing the ray bending ability, and a meta-corrector to eliminate aberration of the optical system. Spatial frequency requirement of the meta-device is significantly reduced since system ray bending ability is mainly provided by refractive element. As a result, a large pixel liquid crystal spatial light modulator is sufficient to demonstrate the concept of meta-corrector for the refractive-meta hybrid system with a numerical aperture of 0.52. It is shown that the focal spot size can be significantly reduced from 322.07 μm to 0.636 μm for ray-tracing simulation, and 101.6 μm to 7.7 μm for measurement, as an appropriate phase distribution of the meta-corrector is added. We believe this pilot experiment can be applied to ball lenses and other optical lens-sets like cookie triplets as well.