Extending the high-order harmonic generation cutoff by means of self-phase-modulated chirped pulses

NEYRA E; VIDELA F; PÉREZ-HERNANDEZ J.A.; CIAPPINA M; ROSO L; TORCHIA G.A.

LASER PHYSICS LETTERS

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2016 vol. 13

1612-2011

In this letter we propose a complementary approach to extend the cutoff in high-order harmonic generation (HHG) spectra beyond the well established limits. Inspired by techniques  normally used in the compression of ultrashort pulses and supercontinuum generation, we  show this extension can be achieved by means of a nonlinear phenomenon known as self- phase-modulation (SPM). We demonstrated that relatively long optical pulses, around 100 fs   full-width half maximum (FWHM), non linearly chirped by SPM, are able to produce a  considerable extension in the HHG cutoff. We have also shown it is possible control this  extension by setting the length of the nonlinear medium. Our study was supported by the  numerical integration of the time-dependent Schrödinger equation joint with a complete  classical analysis of the electron dynamic. Our approach can be considered as an alternative  to the utilization of optical parametric ampliʆcation (OPA) and it can be easily implemented  in usual facilities with femtosecond laser systems. This technique also preserves the harmonic  yield in the zone of the plateau delimited by Ip  +  3.17Up law, even when the driven pulses  contain larger wavelength components.