  A light, compact optical isolator using an atomic vapor in the hyperfine
Paschen-Back regime is presented. Absolute transmission spectra for experiment
and theory through an isotopically pure 87Rb vapor cell show excellent
agreement for fields of 0.6 T. We show \pi/4 rotation for a linearly polarized
beam in the vicinity of the D2 line and achieve an isolation of 30 dB with a
transmission > 95 %.
