title: Axicon based conical resonators with high power copper vapor laser.
abstract: We report for the first time the performance of axicon based conical resonators (ABCRs) in a copper vapor laser, with novel results. The unstable conical resonator comprising of conical mirror (reflecting axicon) with axicon angle approximately pi/18, cone angle approximately 160 degrees, and a convex mirror of 60 cm radius of curvature was effective in reducing the average beam divergence to approximately 0.15 mrad (approximately 25 fold reduction compared to standard multimode plane-plane cavity) with output power of approximately 31 W. Extraction efficiency of approximately 50%-60% and beam divergence of <1 mrad was achieved in other stable ABCR configurations using flat and concave mirrors with the axicon. This is a significant improvement compared to 4-5 mrad normally observed in conventional stable resonators in copper vapor lasers. The conical resonators with copper vapor laser provide high misalignment tolerance beta approximately 4-5 mrad where beta is the tilt angle of the conical mirror from optimum position responsible for approximately 20% decline in laser power. The depth of focus d was approximately three times larger in case of conical resonator as compared to that of standard spherical unstable resonator under similar beam divergence and focusing conditions.
authors.affiliation: Laser System Engineering Division, Raja Ramanna Center for Advanced Technology, Indore 452013, India. bsingh@rrcat.gov.in
authors.forename: Bijendra
authors.initials: B
authors.lastname: Singh
authors.forename: V V
authors.initials: VV
authors.lastname: Subramaniam
authors.forename: S R
authors.initials: SR
authors.lastname: Daultabad
authors.forename: Ashim
authors.initials: A
authors.lastname: Chakraborty