Small dye laser in a semiunstable resonator pumped by an argon-jet guided spark

An argon-jet guided spark of 1-cm length has been constructed, and a small dye laser was pumped by that spark at 150 Hz with 60-nsec pulses. The use of high dye concentrations provided enough gain over a short pathlength. As a consequence of the high concentration and side pumping the cross section of the pumped volume measures only 1.5 x 0.1 mm(2) . This laser of rectangular, cross section lases in one transversal mode due to the application of a novel resonator configuration that is unstable in the vertical plane and stable in the horizontal. An analysis of the factors determining the threshold and of the spatial configuration of this astigmatic mode is given.