Generation of sub-50 fs vacuum UV pulses with more than 2:5 μJ energy at a 1 kHz repetition rate is reported. The pulses at 160 nm are produced using noncollinear difference-frequency four-wave mixing between the fundamental and third harmonics of an amplified Ti:sapphire laser in argon. While the pulse duration is maintained by increasing the phase-matching pressure, noncollinear interaction improves the conversion efficiency by 1 order of magnitude in comparison with the previous results in collinear geometry
