a Co-polarization components of all four optimized unit cells along with their average co-polarization. At the optimized wavelength of 632.8 nm, the average co-polarization transmission is minimized (≈6.2%). b Cross-polarization components of the four optimized unit cells along with their average cross-polarization transmission (η). At the operational wavelength, the average cross-polarization transmission is maximized (≈63%). The black dashed line indicates the working wavelength of 632.8 nm.