Fig. 1. Schematic illustrations of the multifunctional metasurface. (a) The designed metasurface splits the x-polarized incident light into two different directions. (b) The designed metalens focuses the x-polarized incident light on two independent focal spots.

Fig. 2. Optical response for elliptical cylinder at freespace wavelength of 633 nm. All of the phases are in units of rad/π. (a) Schematic of the Si elliptical cylinder located on the quartz with parameters P = 300 nm, H = 410 nm, D_o and D_e. (b) Schematic of the meta-atom optical response. (c), (d) Phase and amplitude of t˜o as functions of D_o and D_e. (e) Phase delay of t˜yx as a function of D_o and D_e. (f)–(h) Phase delay ϕ_xx as a function of the rotation angle α for different phase delays ϕ_yx, which are +0.55π, −0.55π, and ±π and marked with blue triangles, green squares, and red circles in (d) and (e), respectively.

Fig. 3. Simulation results of the metasurface for splitting and deflecting the orthogonal polarization beam. (a) The supercell consisting of sixteen specific nanoposts. (b), (c) The phase delay φ_xx and φ_yx and their corresponding transmission of selected sixteen cells. The black line is the theoretically requested phase delay. (d), (e) The electric field contributions of x-polarization and y-polarization in the x–z plane with x-polarized incident light.

Fig. 4. (a) Top-view SEM image of the metalens. (b) Enlarged SEM image of the metalens in (a). (c) The measurement setup for image reconstruction and polarization characterization of the focal field.

Fig. 5. Scanning confocal images and simulation results of the focal spots in the longitudinal section for four metalenses. (a), (b) Two focal spots of the metalenses are transversely separated. The insert is normalized optical intensity distribution along the dashed line. (c) The focal spots of the metalens are longitudinally separated. (d) The focal spots of the metalens are transversely and longitudinally separated simultaneously. (e)–(h) The corresponding x–z plane simulation results of metalenses in (a)–(d).

Fig. 6. (a) Normalized optical intensity distribution in the focal plane of the first metalens. (b)–(d) The normalized optical intensity distribution in the focal plane of the metalens, inserting a polarizer after the collected objective.

Fig. 7. Simulation result of the metalens with same intensity and shape. (a), (b) The normalized optical intensity distributions in the x–z plane and the focal plane. (c) The normalized optical intensity distribution along the dashed line.