Single-layer antireflection coatings on transparent substrates: Polarization-dependent response at oblique incidence

The polarization-dependent reflection properties of single-layer antireflection coatings (ARCs) on transparent substrates at oblique-incidence are examined in detail. This includes the intensity reflectances |Rp|2and |Rs|2for incident p- and s-polarized light as functions of angle of incidence φ and substrate refractive index n2. For unpolarized or circularly polarized light incident at φ = 45°, we find that the average reflectance is < 2.5% for all values of n2 < 10. The reflectance differenceRD=|Rs|2−|Rp|2exhibits a maximum near φ = 80°, whose magnitude and exact location are functions of n2. At φ = 45°, the RD is a function of n2 that has its own peak of 0.009 at n2 ≈ 2.0. A non-trivial differential reflection phase shift Δ = δp − δs near-normal incidence (φ = 0.1°) is calculated as a function of n2. Finally, the principal angle, principal azimuth, and second Brewster angle that are usually defined for bare absorbing substrates, are determined for single-layer ARCs on transparent substrates as functions of n2.