Anti-reflection quarter-wave coating n_AR = sqrt(n_1 n_2); geometric-mean condition

Layer 1 — Physicsin the thin-films subtree

Anti-reflection (AR) quarter-wave-coating framework (Strong 1936 J Opt Soc Am 26, 73; Macleod 2010 Thin-Film Optical Filters). Setup: a single dielectric layer of refractive index n_AR and thickness d_AR = lambda_0/(4 n_AR) deposited on a…