Affiliations: National Key Laboratory of Science and Technology on
Tunable Laser, Institute of Opto-Electronics, Harbin Institute of Technology,
Harbin, Heilongjiang, China
Note: [] Corresponding author: Yuanqin Xia, National Key Laboratory of
Tunable Laser Technology; Institute of Opto-Electronics, Room 204, Building 2A,
Science Park of Harbin Institute of Technology, 2 Yi Kuang Street, Harbin
150080, Heilongjiang, China. Tel.: +86 45186412753; Fax: +86 45186412753; E-mail: xiahit@126.com
Abstract: We experimentally study the harmonics from a Xe-He gas mixture using
tight-focusing femtosecond laser pulses. The spectrum in the mixed gases
exhibits an extended cutoff region from the harmonic H21 to H27. The potential
explanation is that the harmonics photons from Xe contribute the electrons of
He atoms to transmit into the excited-state. Therefore, the harmonics are
emitted from He atoms easily. Furthermore, we show that there are the
suppressed harmonics H15 and H17 in the mixed gases. The underlying mechanism
is the destructive interference between harmonics generated from different
atoms. Our results indicate that HHG from Xe-He gas mixture is an efficient
method of obtaining the coherent soft X-ray source.
Keywords: Femtosecond laser pulses, soft X-ray, high harmonic generation, gas mixture
