Efficient generation of ultra broadband supercontinuum in a mid-infrared field

Abstract

We theoretically investigate the generation of ultra broadband supercontinuum from helium atoms exposed to a linearly polarized mid-infrared field. By adopting a UV trigger pulse to the mid-infrared field, the continuous harmonic yields are significantly enhanced by 3.5 orders, and a supercontinuum with the width of 230 eV is observed. The spectrum can support a sub-20 as pulse, which is below one atomic unit of time (24 as). The short quantum path is selected by adjusting the time delay between the UV pulse and the mid-infrared pulse, then broadband single 70 as pulses with tunable central wavelengths are obtained, which can be extended to the ‘water window’ region (284–543 eV).

Keywords:

• multiharmonic generation
• ultrafast nonlinear optics
• infrared

Acknowledgements

This work was supported by the National Natural Science Foundation of China under Grant No. 11005088, the Project of Basic and Advanced Technology of Henan Province of China under Grant No.102300410241 and the Science and Technology of Henan Province in China under Grant No. 082300410050.