Fig. 1. Schematic drawings of PBSs based on metasurfaces. Unpolarized light (red arrow) is incident on the structure with an angle of θi and divided into reflected TE (green arrow), −1st and −2nd diffracted TM lights (blue arrows) with diffraction angles of θ0, θ−1, and θ−2, respectively.

Fig. 2. Numerical simulation of the structure. a, The mode effective refractive index Neff changing with width s for MIM waveguide. The blue shading with s<sc indicates the region of only the TM mode. b, The reflected ETRTE/TM0 (dashed lines) and diffracted ETRTM/TE−1 (solid lines) changing with the nano-slit width. c, The splitting angle between the reflected and diffracted light beams. Left and right half figures indicate angles between −1st and −2nd diffracted TM and reflected TE lights, respectively. d, TM reflected spectra changing with h of nano-slits.

Fig. 3. Simulated reflections and diffractions for one-slit and three-slit MNGs with a pitch of 800 nm under incident angle θi=40°. a, RTM0, RTE0, b, RTM−1, RTM−2, and, c, RTE−1, RTE−2 with one (dashed lines) or three slits (solid lines) in each period. The insets in b and c are the simulated electric field for TM and TE light, respectively, for the wavelength of 550 nm and θi=40°. The white dashed lines indicate the surface profile of the structure, and the white arrows depict the incident light. d, The simulated ETRTE/TM0 (red lines), ETRTM/TE−1 (green lines), and ETRTM/TE−2 (blue lines) of TE and TM light.

Fig. 4. Simulated spectra of ETRs for one-slit and three-slit structures. a, ETRTE/TM0, b, ETRTM/TE−1, c, ETRTM/TE−2 for the three-slit case and, d, ETRTE/TM0, e, ETRTM/TE−1, f, ETRTM/TE−2 for the one-slit case with wavelengths of 400–800nm and incident angles of 0°–70°.

Fig. 5. SEM images and measured spectra dependent on incident angle for the 800 nm pitch structure. a, Top view and, b, side view of the fabricated sample. c, Measured reflected, c_I, TE and, c_II, TM spectra and, c_III, ETRTE/TM0 for wavelengths of 400–800nm and incident angles of 5°–70°. d and e, Measured diffracted spectra, d_I, RTE−1, d_II, RTM−1, e_I, RTE−2, e_II, RTM−2 and, d_III, ETRTM/TE−1, e_III, ETRTM/TE−2 for wavelengths of 400–800 nm and incident angles of 20°–60°. As a note, due to the methods of measurement, the reflection spectrum cannot be measured when the angle between the incidence and reflection is less than 5°.

Fig. 6. SEM images and measured spectra dependent on incident angle for the 600 nm pitch structure. a, Top view and, b, side view of the fabricated sample. c, Measured reflected, c_I, TE and, c_II, TM spectra and, c_III, ETRTE/TM0 for different wavelengths and incident angles of 5°–70° in the visible band. d, Measured diffracted spectra, d_I, RTE−1, d_II, RTM−1, and, d_III, ETRTM/TE−1 for incident angles of 25°–70° in the visible band.