Fig. 1. Schematic diagram of the designed metasurface beamsplitter and Dammann grating

Fig. 2. (a) Schematic diagram of the metasurface cell, with a length of 480 nm, a width of 240 nm, a height of 760 nm, and a period of 650 nm. The substrate is 500-μm thick; (b) Efficiency of cross circularly polarized light at 650 nm period. The black dot in (b) is the selected metasurface cell; the length and width of the nanopillar are 480 nm and 240 nm, respectively; the conversion efficiency is 99.2%

Fig. 3. (a, b) One-dimensional simulation of the beamsplitter intensity angle distribution. The blue line is the simulation result, and the orange dashed line is the optimization target; (c) The unwrapped phase of the beamsplitter; (d) The full width at half maximums (FWHMs) of spots in (a). The blue line is the simulation result, the yellow dashed line is the diffraction limit, and the red dotted line is the optimization target; (e) 41 rays on the 40 cm distancing plane obtained by the numerical Rayleigh-Somerphy diffraction integral. Each light spot is cut into 3 mm squares and spliced together

Fig. 4. (a, b) Metasurface morphology imaged by 5x and 100x objective microscopes. Scalebars: 200 μm and 2 μm; (c) Design drawing of the same area in Fig. 4(b), with a scale of 2 μm; (d) Schematic diagram of the experimental optical path. P: polarizer; QWP: quarter-wave plate; MS: metasurface; (e) Captured 41 rays. Each beam is cut into 3 mm squares and spliced together; (f) Experimentally measured power of beams. The blue line represents the beams from the 1^st to 20^th orders and the orange dotted line is from the −1^st to −20^th orders; (g)Experimentally measured FWHMs. The solid blue line with asterisks and the orange dotted line with circles are the horizontal FWHMs from the 1^st to the 20^th orders and from the −1^st to the −20^th orders, respectively. The dashed yellow line with regular triangles and the dashed-dotted purple line with inverted triangles are the vertical FWHMs from the 1^st to the 20^th orders and from the −1^st to the −20^th orders, respectively. The solid green line is the horizontal diffraction limit.