The Competition between Two-Photon Resonance Four Wave Frequency Difference and Sum Mixings

Tunable intense Vacuum Ultraviolet (VUV) laser was generated by two-photon resonant four wave difference frequency mixing (ω-=2ωUV-ωT) in Xenon. In the experiment some resonance attenuations of the VUV were observed at certain difference frequencies. These attenuations occur when the sum frequencies ω+=2ωUV+ωT coincide with excited ns (n=10,11) and nd (n=8~13) states. The third order linear susceptibility χ(3)（2ωUV+ωT；ωUV，ωUV+ωT） is reasonably increased by the double resonance enhancement, so the conversion efficiency of sum frequency mixing can be very high and the power of the pump laser is decreased and thus the difference frequency output is attenuated.