Fig. 1. Schematic of the proposed multifocus metalens for polarization detection. For arbitrarily polarized wave incidence, this metalens converts each of the six polarized components (x-polarized, y-polarized, 45°-polarized, 135°-polarized, LCP, and RCP) of the incident wave into x polarization and focuses them individually at six positions on the same focal plane.

Fig. 2. Characterization of the selected meta-atoms. (a) Simulated phase shifts of the transmitted x-polarized (y-polarized) component under the x-polarized (y-polarized) incidence; (b) simulated transmission amplitudes and phase shifts of the transmitted x-polarized component under the y-polarized incidence; (c) transmission amplitudes and phase shifts of the transmitted x-polarized component under the 45°-polarized incidence; (d) transmission amplitudes and phase shifts of the transmitted x-polarized component under the 135°-polarized incidence; (e) transmission amplitudes and phase shifts of the transmitted x-polarized component under the LCP incidence; (f) transmission amplitudes and phase shifts of the transmitted x-polarized component under the RCP incidence.

Fig. 3. Characteristic of the proposed multifocus metalens for polarization detection: eight linearly polarized incidences. (a) Representation as points on the Poincaré sphere of the detected polarizations (*) and the incident ones (hexagrams); (b) comparison of the simulated azimuth angles and the theoretical ones; (c)–(j) intensity distribution of the transmitted x-polarized component and the comparison of polarization ellipses between the detected polarization states (red) and the incident ones (blue).

Fig. 4. Characteristic of the proposed multifocus metalens for polarization detection: eight elliptically polarized incidences (along the meridian direction). (a) Representation as points on the Poincaré sphere of the detected polarizations (*) and the incident ones (hexagrams); (b) full-Stokes parameters of the detected polarization states (purple) and the incident ones (orange); (c)–(j) intensity distributions of the transmitted x-polarized component and the comparisons of polarization ellipses between the detected polarization states (red) and the incident ones (blue).

Fig. 5. Characteristic of the proposed multifocus metalens for polarization detection: eight arbitrarily elliptically polarized incidences. (a) Full-Stokes parameters of the detected polarization states (purple) and the incident ones (orange); (b) representation as points on the Poincaré sphere of the detected polarizations (*) and the incident ones (hexagrams); (c)–(j) comparisons of polarization ellipses between the detected polarization states (red) and the incident ones (blue).

Fig. 6. Experimental characterization of the proposed multifocus metalens for polarization detection. (a), (b) SEM images of the fabricated metasurface; (c) representation as points on the Poincaré sphere of the measured polarizations (*) and the incident ones (hexagrams); (d)–(i) measured intensity distributions of the transmitted x-polarized component, and full-Stokes parameters of the measured polarization states and the incident ones.

Fig. 7. Intensity distributions of the transmitted x-polarized component under the different polarized incidences.

Fig. 8. Full-Stokes parameters of the detected polarization states (purple) and the incident ones (orange).

Fig. 9. Intensity distributions of the transmitted x-polarized component under arbitrarily elliptically polarized incidences.