  We demonstrate an atomic Faraday dichroic beam splitter suitable to spatially
separate signal and idler fields from pump degenerate four-wave mixing in an
atomic source. By rotating the plane of polarization of one mode $90^{\circ}$
with respect to the other, a subsequent polarizing beam splitter separates the
two frequencies, which differ by only 13.6 GHz, and achieves a suppression of
$(-26.3\pm0.1)$ and $(-21.2\pm0.1)$ dB in the two outputs, with a corresponding
transmission of 97 and 99 %. This technique avoids the need to use spatial
separation of four-wave mixing modes and thus opens the door for the process
efficiency to be enhanced in waveguide experiments. As a proof-of-principle we
generate light via four-wave mixing in $^{87}$Rb loaded into a hollow-core
photonic crystal fiber and interface it with the atomic Faraday dichroic beam
splitter.
