Fig. 3: Structural and spectral characteristics of the SSFE.
a The optimized thickness distribution of the 10-layer SSFE. The first layer is near the substrate side. The total thickness is 7393 nm, and the thicknesses for the TiO2 and SiO2 layers are 4097 nm and 3296 nm, respectively. b Measured angle-dependent spectral responses under different polarization states in the visible wavelength range. The complex spectral response, characterized by various peaks and valleys, contributes to low correlation, which supports efficient encoding. c Measured transmittance across several distinct positions on the 4-inch-diameter SSFE in the visible and near-infrared wavelength range. The dashed lines serve as references to highlight the consistency of peak/valley wavelengths. d Correlation coefficients of the spectral responses in the visible wavelength range. A remarkably low average correlation of 0.19 is achieved.
