Fig. 2: Multilayer HMM characterization and simulation.

a Transmittance (T) and reflectance (R) at normal incidence of the Ag-SiO₂ multilayer HMM. Inset image: a photo of the HMM-coated cover glass. Calculation is done based on transfer matrix method for 3 pairs of {10 nm Ag and 4 nm SiO₂} on glass. b AFM image of the top surface. Scan area: 3 μm × 3 μm (512 pixels × 512 pixels). c TEM cross-section shows 3 pairs of 10 nm Ag and 4 nm SiO₂ on top of a glass substrate with Cr adhesion layer. d–f Simulated light intensities (|E | ²) on x-y plane at 10 nm on top of the HMM. The total simulated size of illumination pattern is 1 μm × 1 μm. d θ = 0°, λ = 500 nm; e, θ = 45°, λ = 500 nm; f θ = 0°, λ = 600 nm. θ is the incident angle; λ is the operating wavelength. g Schematics of the experimental set-up of speckle-MAIN.