The present invention provides optical configurations, including resonant cavity and laser configurations, and related methods providing deterministic control of the polarization characteristics and frequencies of the radiant output of multi-longitudinal mode lasers, including multi-longitudinal mode gas phase lasers. Polarization control provided by the present invention includes preselection and stabilization of the angular orientations of the polarization planes of electromagnetic radiation generated by a multi-longitudinal mode laser, including preselection and stabilization of orthogonal linear polarization states generated by a dual-longitudinal mode gas phase laser.