“…6b shows the reflectivity of Au (150 nm)/Ti/SiO 2 as a function of SiO 2 thickness for Ti thicknesses of 2, 3, 5, 10, and 15 nm. The refractive index, which was obtained by fitting the reported experimental data points 20–22, was used to calculate the reflectivity. The amplitudes of the incident/reflected waves and the reflectivity of metal–dielectric HR‐coated layers are given by 23 Here, B sd (semiconductor–dielectric), B dt (dielectric–Ti), B tg (Ti–Au), and B ga (Au–air) are backward‐propagation matrixes, r is the reflection coefficient, and t is the transmission coefficient.…”