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

F. VIDELA; L ROSO; F. VIDELA; L ROSO; J A PÉREZ-HERNÁNDEZ; G A TORCHIA; J A PÉREZ-HERNÁNDEZ; G A TORCHIA; NEYRA, ENRIQUE ; M F CIAPPINA; NEYRA, ENRIQUE ; M F CIAPPINA

LASER PHYSICS LETTERS

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2016

1612-2011

In this letter we propose a complementary approach to extend the cutoff in high-orderharmonic generation (HHG) spectra beyond the well established limits. Inspired by techniquesnormally used in the compression of ultrashort pulses and supercontinuum generation, weshow this extension can be achieved by means of a nonlinear phenomenon known as selfphase-modulation (SPM). We demonstrated that relatively long optical pulses, around 100 fsfull-width half maximum (FWHM), non linearly chirped by SPM, are able to produce aconsiderable extension in the HHG cutoff. We have also shown it is possible control thisextension by setting the length of the nonlinear medium. Our study was supported by thenumerical integration of the time-dependent Schrödinger equation joint with a completeclassical analysis of the electron dynamic. Our approach can be considered as an alternativeto the utilization of optical parametric amplification (OPA) and it can be easily implementedin usual facilities with femtosecond laser systems. This technique also preserves the harmonicyield in the zone of the plateau delimited by Ip + 3.17Up law, even when the driven pulsescontain larger wavelength components.