An unconventional optical sparse aperture metalens

Abstract

Metalens consisting of arrays of subwavelength nanostructures with ultrathin, lightweight, and tailorable characteristics have been in the spotlight to develop next-generation optical elements beyond existing refractive or diffractive optics. However, billions of subwavelength nanostructures of the metalens pose a serious challenge for fabrication, especially for the large-area ones. Herein, we designed and fabricated an unconventional optical sparse aperture (UOSA) metalens that consists of four identical and concentric annular sectors sub-aperture metalens, and it has the larger nonzero domain of modulation transfer function compared with the OSA metalens. The numerical simulation and experiments jointly show that the UOSA metalens has a limited diffraction resolution (0.91 µm) as the conventional full aperture metalens. The UOSA method can not only enlarge the effective aperture of the metalens with lower cost and less processing time but also extend a new degree of freedom for the design of the OSA metalens.