Fig. 1. (a) Schematic image of a low-loss hydrogenated amorphous silicon (a-Si:H) meta-atom on a glass substrate. (b) Top view of metalens building blocks with a rectangular array. (c) Measured refractive index n and extinction coefficient k of low-loss a-Si:H. (d)–(f) Simulated phase and transmittance for meta-atoms as a function of diameter (D) at λ  of (d)450, (e) 532, and (f) 700 nm. Height(H)=600  nm; period (P)=230  nm for λ=450  nm; P=460  nm for λ=532 and 700 nm.

Fig. 2. (a) Schematic illustrations of spatial interleaving method with three meta-atoms: λ=450, 532, and 700 nm for blue, green, and red circles, respectively. (b) Simulated cross-sectional normalized electric field distributions of the metalens at λ=450  nm (top), 532 nm (middle), and 700 nm (bottom) in the focal region. (c)–(e) Calculated normalized electric field distributions at the focal spot at λ  of (c)450  nm, (d) 532 nm, and (e) 700 nm. Scale bar: 500 nm.

Fig. 3. (a), (b) Scanning electron micrograph of the fabricated metalens for (a) top-down and (b) tilted SEM images. (c) Schematic illustration of the optical setup. (d) Normalized measured optical field intensity profiles at λ=450  nm (top), 532 nm (middle), and 700 nm (bottom).

Fig. 4. (a)–(c) Captured image of the focal spot created by the metalens at λ of (a)450  nm, (b) 532 nm, and (c) 700 nm. (d)–(f) Normalized cross-sectional intensity profiles and Airy functions at λ of (d)450  nm, (e) 532 nm, and (f) 700 nm. (g)–(i) MTF of the metalens at λ of (g)450  nm, (h) 532 nm, and (i) 700 nm.

Fig. 5. (a) Experimental setup for imaging setup. (b) Captured image of a negative 1951 USAF resolution target using the SIM metalens at λ=532  nm.

Fig. 6. (a) Screen-capture system in bright and dark conditions. (b) Captured image of the same number “5” at λ=450, 532, and 700 nm.

Fig. 7. Simulated transmission properties of the meta-atoms of 40 nm≤D≤110  nm, 400 nm≤H≤800  nm at λ=450  nm. (a) Phase. (b) Transmittance. The period was set to 230 nm, which satisfies the Nyquist sampling criteria. Black lines: optimized structures used in this work to achieve full-phase coverage with high efficiency.

Fig. 8. Simulated (a) phase and (b) transmittance of the meta-atoms of 60 nm≤D≤110  nm, 150 nm≤P≤250  nm at λ=450  nm. Simulated (c) phase and (d) transmittance of the meta-atoms of 80 nm≤D≤160  nm, 350 nm≤P≤500  nm at λ=532  nm. Simulated (e) phase and (f) transmittance of the meta-atoms of 100 nm≤D≤300  nm, 350 nm≤P≤500  nm at λ=700  nm. The H is set to 600 nm, which is the optimization result in Fig. 7. Black lines: optimized structures used in this work to achieve full-phase coverage with high transmittance while avoiding anomalous diffraction.

Fig. 9. (a) Schematic image of the custom-built setup for efficiency measurement depending on the polarization. (b) Measured focusing efficiency of the SIM metalens according to polarization variation.

Fig. 10. (a) Schematic image of slanted meta-atom on the glass substrate. (b)–(d) Simulated phase for slanted meta-atoms as a function of D at λof(b)450, (c) 532, and (d) 700 nm. Height (H)=600  nm; period(P)=230  nm for λ of 450  nm; P=460  nm for λ=532 and 700 nm. θ=2.5°, 3.5°, and 4.5° for λ=450, 532, and 700 nm, respectively.