Linear-to-circular polarization transformation upon reflection by a transparent thin film on a transparent substrate: analytical determination of principal angles and principal azimuths

The principal angles and principal azimuths at which incident linearly polarized light becomes circularly polarized upon external reflection by a transparent thin film on a transparent substrate are determined analytically. For a given principal angle, multiple solutions (two or four) are obtained for the required film thicknesses and the associated principal azimuths. Specific results are presented for the air-SiO -Si (ambient-film-substrate) system at the near-infrared wavelength λ=1.55 μm.