AN UNSTABLE RESONATOR LASER WITH A MODIFIED OUTPUT COUPLING SCHEME

Unstable resonator lasers with a scraper mirror as output coupler suffers from diffraction effects associated with uniformly illuminated aperture. The near-field intensity distribution is annular in shape with minima at the center. In this communication, a modified resonator is suggested in which the resonator is folded and the scraper mirror is replaced by a partially transmitting mirror to provide the output coupling. The modified resonator is applied to a copper vapor laser. Observed near-field distribution is uniform across the beam and the intensity of the diffraction rings in the far-field profiles is considerably reduced.