A generator produces a flow of gaseous molecular oxygen in the singlet sigma and/or singlet delta excited electronic states. The generator is comprised of an optical source; coupling optics to transport and concentrate optical source light; a vacuum chamber, reflective optics; a wall cooling system; an inlet system for injecting oxygen; an inlet system for injecting other gases which deactivate singlet sigma oxygen to singlet delta oxygen; and a means for interfacing this device to a lasing device and for directly flowing the singlet sigma or singlet delta oxygen into a laser cavity.