Experimental study of self-injection locking oscillator on copper vapor laser

As a novel method to obtain a low divergence laser beam, a self-injection locking oscillator system has been developed for a copper vapor laser. The system is made of one laser tube, and uses temporal superposition of two pulsed discharges, predischarge and main discharge. The laser pulse is produced in the main discharge by amplifying a seeded laser pulse produced by the predischarge. By optimizing the discharge conditions including an interval period between the two pulsed discharges, a high quality laser beam containing 80% of the whole laser beam energy in divergence as small as eight times diffraction limited has been obtained. The quality of the laser beam is comparable to that obtained with a conventional injection locking oscillator system consisting of two separate laser tubes.