Signature of multi-channel interference in high-order harmonic generation from N2 driven by intense mid-infrared pulses

TL;DR

This study reveals multi-channel interference effects in high-order harmonic generation from N2 molecules driven by mid-infrared lasers, showing spectral minima that depend on laser intensity but not on molecular alignment.

Contribution

It provides experimental evidence of dynamic multi-channel interference in HHG from N2 using mid-infrared pulses, highlighting the role of laser intensity in spectral minima shifts.

Findings

Spectral minima observed in HHG spectra at all three wavelengths.

Minima positions are independent of molecular alignment angles.

Minima shift linearly with increasing laser intensity.

Abstract

We investigate the multi-electron dynamics in high-order harmonic generation (HHG) from N2 molecules. Clear spectral minima are observed in the cutoff region at all three mid-infrared wavelengths (i.e., 1300, 1400 and 1500 nm) chosen in our experiment. It is found that the positions of the spectral minima do not depend on the alignment angles of molecules. In addition, the spectral minima shift almost linearly with the increasing laser intensity at all three wavelengths, which provides a strong evidence on the dynamic multi-channel interference origin of these minima. The advantages of observation of dynamic multi-channel interference based on HHG driven by long wavelength lasers are discussed.