Fig. 1. Metalens design. (a) Schematic illustration of a metalens that converts a plane wave with an oblique angle θ into a spherical wave, which is focused into a focal point in the focal plane at a distance of P(θ) away from origin O. Tilt view of (b) a normal structure with α = 0° and (c) a tilted structure on the SiO₂ substate. Simulated (d)–(g) phase and (h)–(k) transmission of the structures of 50 nm ≤ w_x ≤ 360 nm, 50 nm ≤ w_y ≤ 360 nm at λ = 850 nm, of which α and θ are the same, with values of 0°, 10°, 20°, 30°, respectively. Green triangle marks: selected structures used in this work. (l)–(o) Phase (black circle markers) and transmittance (red square markers) of the chosen eight different structural parameters, of which the phase can cover 0–2π and transmission is all above 0.9.

Fig. 2. Comparison of focal spots according to dynamic phase based metalenses with (a) α = 0°, (b) α = 10°, (c) α = 20°, (d) α = 30° at incident angles of −20°, −10°, 0°, 10°, 20°, 30°, 40°, 50°, and 60°. The images at the top show the energy in the x–z plane. The images at the bottom show the energy in the focal (x–y) plane. (e)–(h) Cross-section view (f = 35 µm) of the intensity distribution along the x-direction shown in (a)–(d).

Fig. 3. Focusing performance of metalenses based on dynamic phase. Comparison of (a) transmission, (b) diffraction efficiency, and (c) total efficiency of the lens with four different α as a function of incident angle. Data points (rectangle mark) and data points (circular mark) represent α = 0° and α > 0°, respectively, and the solid lines are eye guides. MTFs of the lens with (d) α = 0°, (e) α = 10°, (f) α = 20°, (g) α = 30° in the sagittal plane.

Fig. 4. Focusing results of metalenses based on geometric phase. (a)–(d) Cross-section view (f = 35 µm) of the intensity distribution along the x-direction. Comparison of (e) transmission, (f) diffraction efficiency, (g) total efficiency, and (h) PCR of the lens with four different α as a function of incident angle. Data points (rectangle mark) and data points (circular mark) represent α = 0° and α > 0°, respectively, and the solid lines are eye guides. MTFs of the lens with (i) α = 0°, (j) α = 10°, (k) α = 20°, (l) α = 30° in the sagittal plane.

Fig. 5. (a) Focal spots of 7 metalenses with different design angles. (b) Imaging range of each lens in the metalens array. (c) Total efficiency of the normal metalens array and hybrid metalens array. (d) Wide-angle imaging of the normal metalens array and the hybrid metalens array. The two images on the right represent the enlarged image at the dashed line.