Highly coherent high-energy high-order harmonic generation

We demonstrated the generation of highly-coherent high-order harmonics and their energy scaling in the soft x-ray region using 30-fs Ti:sapphire laser pulses. By adjusting the gas density and the pump laser focusing, an output energy as high as 0.5 (mu) J was achieved with good spatial beam quality having a beam divergence of 2 mrad at the 27th harmonic (30 nm).