Better magneto-optical filters with cascaded vapor cells in the Faraday-Faraday and Faraday-Voigt geometries. [Dataset]

Magneto-optical filter performance is often measured using a figure of merit where the equivalent noise bandwidth is minimized as the transmission is maximized. There are also application specific criteria to consider such as whether to use a ‘wing’ or ‘line center’ filter . We show that by cascading two cells with independent axial (Faraday) or transverse (Voigt) magnetic fields with respect to the k-vector of the light, improved performance can be achieved for both applications. The first cell optically rotates the plane of polarization of light creating the high transmission window. The second cell selectively absorbs the light eliminating unwanted transmission. We realize a Faraday-Faraday wing filter and the first recorded Faraday-Voigt line center filter which show excellent agreement with theory. The two filters have FOM values of 0.86 and 1.63 GHz$^{-1}$ respectively, the latter of which is the largest FOM atomic line filter recorded.