Beta barium borate (BBO) crystals have recently become available in the Brewster angle form and dimensions appropriate for broadly tunable angle matched intracavity doubling in a ring dye laser. Using the smooth-tuning geometry previously described1 (which yields a lowest-order Gaussian mode intensity profile and no tuning gaps), we report here the generation of single frequency radiation tuned over the range from 215 to 235 nm with a peak output power of 5 mW at 225 nm. These results are for an 8-mm long crystal cut to produce a 63° phase matching angle (for 225-nm output) at the Brewster angle of Incidence to the fundamental beam in the collimated arm of the ring laser. The doubled light was coupled out of the cavity by a Brewster angle beam splitter with a longwave pass coating on one side to give >95 % reflectivity for the s-polarized UV light while having negligible (<0.1 %) loss for the fundamental. The stilbene-3 dye jet was pumped by a 5-W all-lines mid UV2 beam from a large frame argon-ion laser which gave 60 W of circulating dye fundamental power at the 450-nm peak of the tuning curve in the all high reflector dye cavity.
© 1989 Optical Society of AmericaPDF Article