Two-photon resonant upconversion in xenon

Abstract
Coherent radiation at various VUV wavelengths, e.g., 125.9, 126.1, and 125.4 nm, has been generated through four-wave mixing processes enhanced by two-photon resonances in xenon. Maximum efficiencies of the order of 10−4 were achieved. Maximum output intensities of difference generation (2ω1 − ω2) for 7p[0½]0, 7p[1½]2, and 6p′[1½]2 resonant states occurred at xenon pressures of 24, 12.5, and 4 Torr, corresponding to values of phase mismatch per atom of 1.2 × 10−18, 2.3 × 10−18, and 7.1 × 10−18 esu, respectively. Parametric generation at 117.0 nm through the 7s[112]1° state was also observed.