Continuous second-harmonic generation of λ2572 Å using the argon II laser

Continuous second-harmonic generation of λ 2572 Å in KDP has been observed using the λ 5145 Å AII laser transition. Optimum phase matching between the harmonic and fundamental beams, normal to the optic axis, was obtained at -13.7°C. The dependence of harmonic power on crystal temperature and on the degree of focusing of the fundamental beam was measured and compared with the theory of Boyd and Kleinman. Calculations indicate that if the axial modes of the AII laser are AM phase locked, then ∼100 mW at λ 2572 Å can be obtained for ∼1.0 W at λ 5145 Å with crystal lengths of a few centimeters. Enhancements of average second-harmonic power of ∼30 have been observed resulting from phase locking of the modes.