 A Faraday filter, magneto-optical filter, FADOF or EFADOF (Excited Faraday Dispersive Optical Filter) works by rotating the polarization of the light passing through the vapor cell. This rotation occurs near its atomic absorption lines by the Faraday effect and anomalous dispersion. Only light at the resonant frequency of the vapor is rotated and the polarized plates block other electromagnetic radiation. This effect is related to and enhanced by the Zeeman Effect, or the splitting of atomic absorption lines in the presence of the magnetic field. Light at the resonant frequency of the vapor exits a FADOF near its original strength but with an orthogonal polarization.
