Fig. 1. Schematic of a one-dimensional (1D) metalens composed of catenary-like structures. The metalens converges the incident light onto the focal spot. The FDO method is utilized to correct the propagation phases of the metalens.

Fig. 2. (a) Top views of the initial and optimized catenary and catenary-like optical devices with a diffraction angle of 45°. (b) Schematic of the diffraction efficiencies (Eff.) of the devices with diffraction angles of α = 45° and 75°.

Fig. 3. (a) Evolution of the efficiencies of the catenary-like 1D metalens with CP incidence. (b) The normalized light intensity distributions on the focal plane of the initial and optimized metalenses with CP incidence. (c) The distribution of light intensity on the XoZ plane with CP incidence. (d–f) The efficiencies and light intensity distributions of the metalenses with LP incidence.

Fig. 4. (a) Schematic of the catenary library. The inner dashed box part indicates the continuous part of the catenaries; the outer box part denotes the part of the rectangles. (b, c) The efficiencies of the equal-width catenary arrays (dashed lines), optimized catenary arrays via the FDO method (solid lines), and the predicted catenary arrays via the library (*). (d) The efficiencies of the catenary-like metalenses with equal width and predicted width, with NA ranging from 0.1 to 0.7.

Fig. 5. (a) The scanning electron microscope image of the metalens designed using the library with NA=0.3 and D_lens=6000 μm. (b) The experimental focusing efficiencies of the metalenses with NA=0.3, 0.4, and 0.5. (c) The experimental zero-order efficiencies. (d–f) Comparison of the background noise at the focal plane of the catenary-like metalenses with equal-width and predicted-width overexposure.