Decoding phase and time-dependent interferograms of high-order harmonics

TL;DR

This paper introduces a method using phase and time-delay control in high-harmonic interferograms to enhance harmonic yield and analyze electron dynamics in molecules and solids.

Contribution

It demonstrates that adjusting phase difference alongside time-delay significantly improves harmonic yield and provides deeper insight into electron trajectories in high-harmonic generation.

Findings

Maximum harmonic yields can be orders of magnitude higher with phase and time-delay control.

Two-dimensional interferograms reveal optimal parameters for harmonic enhancement.

The method simplifies analysis of electron dynamics in complex systems.

Abstract

Interferometric measurements of high-harmonics induced by multiple laser fields in an emerging field of research that promises optimized yield of harmonics, and time and space-resolved nonlinear spectroscopy. Most of the measurements have been done by controlling the time-delay between the pulses. Here, we show that by changing one additional parameter, i.e. the phase-difference between the fields, together with the time-delay, one can, on the one hand, enhance the harmonic yield and, on the other hand, obtain in-depth information about the physical mechanisms that control the electron trajectories contributing to the high-harmonic generation. The two-dimensional interferograms obtained from such investigations can be used to find the values of time-delay and phase between the laser fields that maximize the yield of a particular harmonic. Results show that maximum yields of certain harmonics can be orders of magnitude larger than when using a single field or two fields with zero time-delay and phase difference. Our high-harmonics two-dimensional interferograms-based method paves the way for a simpler analysis of the attosecond electron dynamics in complex molecules and solids.