High-order harmonic generation from Xe–Ar gas mixture in the tight focusing laser

• High harmonic generation in Xe–Ar gas mixture is proposed.
• The harmonic is extended from H33 to H37.
• High harmonic generation in cutoff region is decreased in plateau region.
• The mechanism relies on the destructive interference between harmonics.

We report on the harmonics radiation and spectrum properties in the Xe–Ar gas mixture by using tight focusing laser pulses. The cutoff position is extended from the harmonic H33–H37 in mixed gases. The extended orders are attributed to the harmonic radiation from Xe+. We observe that the harmonics are decreased in the plateau region. The result is attributed to the destructive interference of the harmonics generated from the different atoms. Our results suggest that using the Xe–Ar mixture as nonlinear can obtain the coherent XUV source.