Metalens based on constructive interference.

A metalens consisting of nanometer rectangular holes etched on silver film is proposed, and the focusing effect is actualized in the visible region. The rectangular holes are arranged on concentric circles, and the fields excited by these holes constructively interfere due to having the same propagation phase. The propagation phase is obtained by optimizing the sizes of the rectangular holes and the radii of the circles. This metalens can focus linearly or circularly polarized light, and numerical simulations and experimental measurement confirm its focusing performance. The proposed metalens has the advantages of flexible design, loose constraint to incident polarization, low-cost equipment, and simpler experimental operation, and we believe it will be useful to applications in optical integration and visible light imaging.