Chirp-control of resonant high-order harmonic generation in indium ablation plumes driven by intense few-cycle laser pulses

TY - JOUR

T1 - Chirp-control of resonant high-order harmonic generation in indium ablation plumes driven by intense few-cycle laser pulses

AU - Abdelrahman, Z.

AU - Khokhlova, M. A.

AU - Walke, D. J.

AU - Witting, T.

AU - Zair, A.

AU - Strelkov, V. V.

AU - Marangos, J. P.

AU - Tisch, J. W.G.

PY - 2018/6/11

Y1 - 2018/6/11

N2 - We have studied high-order harmonic generation (HHG) in an indium ablation plume driven by intense few-cycle laser pulses centered at 775 nm as a function of the frequency chirp of the laser pulse. We found experimentally that resonant emission lines between 19.7 eV and 22.3 eV (close to the 13th and 15th harmonic of the laser) exhibit a strong, asymmetric chirp dependence, with pronounced intensity modulations. The chirp dependence is reproduced by our numerical time-dependent Schrodinger equation simulations of a resonant HHG by the model indium ion. As demonstrated with our separate simulations of HHG within the strong field approximation, the resonance can be understood in terms of the chirp-dependent HHG photon energy coinciding with the energy of an autoionizing state to ground state transition with high oscillator strength. This supports the validity of the general theory of resonant four-step HHG in the few-cycle limit.

AB - We have studied high-order harmonic generation (HHG) in an indium ablation plume driven by intense few-cycle laser pulses centered at 775 nm as a function of the frequency chirp of the laser pulse. We found experimentally that resonant emission lines between 19.7 eV and 22.3 eV (close to the 13th and 15th harmonic of the laser) exhibit a strong, asymmetric chirp dependence, with pronounced intensity modulations. The chirp dependence is reproduced by our numerical time-dependent Schrodinger equation simulations of a resonant HHG by the model indium ion. As demonstrated with our separate simulations of HHG within the strong field approximation, the resonance can be understood in terms of the chirp-dependent HHG photon energy coinciding with the energy of an autoionizing state to ground state transition with high oscillator strength. This supports the validity of the general theory of resonant four-step HHG in the few-cycle limit.

KW - Plasma high harmonic generation

KW - attosecond physics

UR - http://www.scopus.com/inward/record.url?scp=85048370837&partnerID=8YFLogxK

U2 - 10.1364/OE.26.015745

DO - 10.1364/OE.26.015745

M3 - Article

AN - SCOPUS:85048370837

SN - 1094-4087

VL - 26

SP - 15745

EP - 15758

JO - OPTICS EXPRESS

JF - OPTICS EXPRESS

IS - 12

ER -