Bx53 fluorescent microscope

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.

Atomic force microscopy (AFM, Bruker Multimode 8) was used to examine the thickness and surface roughness of both PPD and PVD films. A tapping mode was employed at the ambient condition with various scan sizes and at a scan rate of 1 Hz. The detailed surface morphology was inspected by scanning electron microscopy (SEM, Hitachi S-4700 FESEM) with an acceleration voltage of 5 keV and a current of 10 µA. A thin layer of gold/palladium was sputtered (Cressington sputter coater 108) on the samples to enhance imaging resolution prior to SEM measurements. Optical properties (refractive index n, extinction coefficient k) of PPD and PVD films and dielectric layers were measured by UV-NIR spectroscopic ellipsometry (J.A. Woollam, M-2000). Olympus BX53 fluorescent microscope coupled Horiba iHR320 imaging spectrometer was utilized to record all the optical images and reflectance spectra of fabricated samples. A protected silver mirror (Thorlabs, PF10-03-P01) was used as a reference to calculate the relative reflectance of the samples, which has optical reflectance over 97.5% in the visible wavelength range.