Generation of high-order harmonics with ultra-short pulses from filamentation

7-fs-pulses with 0.3 mJ are obtained after filamentation in argon and compression by double-chirped-mirrors. These pulses are used to generate high-order harmonics in a semi-infinite gas cell in different noble gases. Spectral broadening of high-order harmonics in xenon and argon is observed. In neon, an extended continuous cut-off region down to 10 nm (124 eV) is observed which is to the best of our knowledge the highest cut-off energy obtained by filamented pulses. Our result suggests the feasibility of single attosecond-pulse-generation at both high photon flux and high cut-off energy. (C) 2009 Optical Society of America