Saqwp05m 700

Eight polarization states were induced with a broadband linear polarizer (WP25M-UB by Thorlabs, Inc.) and super achromatic QWP (SAQWP05M-700 by Thorlabs, Inc.). The induced polarization states are then normally incident onto the polarimetric imager. Images were taken with sufficient exposure time to ensure a high enough signal-to-noise ratio (SNR). The instrument matrix of each super-pixel was then calculated in MATLAB according to the transmitted intensities of each metasurface filter.

The electrical properties of the fabricated devices were characterized under dark and light‐illuminated conditions using Keithley 4200 and Agilent 4155B semiconductor characterization system (SCS) parameter analyzers. Laser diodes emitting light with a wavelength of 520 nm (L520P50, Thorlabs) were used to illuminate the devices. CP light was obtained by combining a linear polarizer (10GT04, Newport) with a quarter‐wave plate (SAQWP05M‐700, Thorlabs). The on/off modulation of incident CP light was controlled by a mechanical optical shutter (SH1, Thorlabs). Before the characterization, the intensities of the RCP and LCP light (P_in) were measured using a standard Si‐based photodetector (DET10A, Thorlabs).

For the chiral metasurface, the unpolarized laser was first polarized by linear polarizer (WP25M-UB by Thorlabs, Inc.) and super achromatic QWP (SAQWP05M-700 by Thorlabs, Inc.) to generate LCP, RCP input, respectively. The CP light is then focused onto the sample with a focal spot size of 15 um in diameter. The transmission efficiency was then measured using Olympus BX53 fluorescent microscope and Horiba iHR320 visible spectrometer. The CPER of LCP chiral metasurface was calculated using the formula: $E=T_{\mathit{LCP}}/T_{\mathit{RCP}}$ , where $T_{\mathit{LCP}},T_{\mathit{RCP}}$ denotes the transmission efficiency of LCP and RCP input, respectively. As for double-layer gratings, the transmission efficiency of TE-mode TM mode linearly polarized input was measured respectively to calculate LPER, using the equation LPER = T_x/T_y, where T_x, T_y denotes the transmission efficiency of LP input along x axis and y axis, respectively.