Two-Photon Resonant, Four-Wave Mixing in Xenon-Argon Gas Mixtures

Abstract

Tunable vacuum ultraviolet (VUV) light in the region from about 115.7 to 116.9 nm was produced using the two-photon resonant, four-wave mixing scheme in Xe. In contrast to previous work, we used Ar to achieve phase matching and a tunable infrared source which enabled us to produce light pulses containing up to 0.7 ..mu..J within the above VUV tuning range. In order to generate the VUV light, the 200 mJ/pulse second harmonic output of a 10 Hz, Q-switched Nd:YAG laser (Quanta-Ray DCR-1A) pumped two tunable dye lasers with 0.3 cm/sup -1/ bandwidths. The wavelength at 252.5 nm, lambda/sub 1/, was generated by mixing the doubled output of dye laser 1 with the residual 1.06-..mu..m pump laser output which had about a 1 cm/sup -1/ bandwidth. Its wavelength was fixed so that two lambda/sub 1/ photons could excite ground state Xe to the 6p state. Dye laser /sub 2/ was used to pump a hydrogen Raman cell whose second stokes-shifted output produced lambda 2 radiation from 1.33 to 1.62 ..mu..m. The 0.2 mJ lambda/sub 1/ and lambda/sub 2/ pulses were focused with separate 42 cm focal length lenses and then made coaxial by use of a dichroic beam combiner before enteringmore » the Xe-Ar four-wave mixing generation cell.« less