Laser mode control using external inverse cavity

A laser mode control system for suppressing anti-symmetric resonance modes of a beam of radiation in a laser resonator cavity. The system includes a main resonator cavity in which a beam of radiation having symmetric and anti-symmetric resonance modes propagates. The main resonator cavity has at least one exit plane at a first end of the cavity through which the propagating beam of radiation passes. The system further includes an external cavity located outside of the main resonator cavity and adjacent to the exit plane. The external cavity includes a mirror for reflecting the beam of radiation passing through the exit plane and for flipping a mode profile associated with the beam of radiation upon the beam of radiation being reflected from the mirror. The external cavity also includes a partially transmissive medium between the mirror and the main resonator cavity for introducing losses to the beam of radiation in the external cavity. The mirror and the partially transmissive medium of the external cavity together suppress the higher order anti-symmetric resonance modes of the beam of radiation, thereby increasing beam quality and reducing the cavity misalignment sensitivity.