Abstract

In this paper, we report on the generation of tunable radiation around 79 nm, using frequency mixing of two ArF^* photons and a visible dye laser photon. In contrast to harmonic generation with a rather limited tuning range, this method combines the potential of high power excimer lasers (up to 30 W peak powers have recently been measured¹ at the third harmonic of ArF^*) with the broad tunability of dye lasers. The ArF^* lasers used in the present experiments is a modified version of a system described previosuly.² The output characteristics of the ArF^* laser are energy 200 mJ, bandwidth 0.5 cm⁻¹, pulse duration 7 ns, and wavelength 193.55 nm. The tunable dye laser was operated with stilbene 420, tunable from 416 nm to 458 nm, with an output energy of 5 mJ, bandwidth 0.3 cm⁻¹, and pulse duration 15 ns. With these lasers, up to 200 mW peak power of mixed radiation have been measured with hydrogen as nonlinear medium. This radiation has a bandwidth of less than 0.8 cm⁻¹, if gaussian lineshapes are assumed. In order to demonstrate the usefulness of the system as a spectroscopic tool, the source was tuned across the ²P_½ 9d' autoionizing resonance in argon. Fig. 1 shows the measured absorption profile normalized to the data from Hudson and Carter³. The bandwidth of the source can be tested by scanning across the ²P_3/2 13d states which have an estimated doppler width of 0.22 cm⁻¹

© 1982 Optical Society of America