Detailed study of quantum path interferences in high harmonic generation driven by chirped laser pulses

Tamás Csizmadia,Paraskevas Tzallas,Peng Ye,Katalin Varjú,Balázs Major,Subhendu Kahaly,Giuseppe Sansone,Lénárd Gulyás Oldal,Valer Tosa,Szilárd Majorosi

doi:10.1088/1367-2630/ac3c0c

Abstract

We investigate the electron quantum path interference (QPI) effects during high harmonic generation in atomic gas medium driven by ultrashort chirped laser pulses. To achieve that, we identify and vary the different experimentally relevant control parameters of such a driving laser pulse influencing the high harmonic spectra. Specifically, the impact of the pulse duration (from the few-cycle to the multi-cycle domain), peak intensity and instantaneous frequency is studied in a self-consistent manner. Simulations involving macroscopic propagation effects are also considered. The study aims to reveal the microscopic background behind a variety of interference patterns capturing important information both about the fundamental laser field and the generation process itself. The results provide guidance towards experiments with chirp control as a tool to unravel, explain and utilize the rich and complex interplay between QPIs including the tuning of the periodicity of the intensity dependent oscillation of the harmonic signal, and the curvature of spectrally resolved Maker fringes.

Highlights

Coherent light sources in the extreme ultraviolet (XUV) and soft x-ray regimes is considered as one of the most useful resources to observe and manipulate various physical, chemical, and biological systems at their natural spatial and temporal scales [1,2,3]
We investigate the electron quantum path interference (QPI) effects during high harmonic generation in atomic gas medium driven by ultrashort chirped laser pulses
We have studied in detail the chirp dependence of QPIs both on the single-atom level, as well as by macroscopic simulations, and demonstrated how a wide group of chirp-connected properties of the fundamental laser pulse, such as pulse duration, peak intensity and instantaneous frequency affect the QPI patterns

Summary

Introduction

Coherent light sources in the extreme ultraviolet (XUV) and soft x-ray regimes is considered as one of the most useful resources to observe and manipulate various physical, chemical, and biological systems at their natural spatial (nanometric) and temporal (attosecond) scales [1,2,3] Due to their relative compactness and low implementation cost, sources based on high harmonic generation in gases (GHHG) [4, 5] are the front-runners in generating coherent electromagnetic radiation in the short wavelength domain [6,7,8,9]. Characterization and control of the intensity, temporal spacing, and duration of the individual atto-pulses constituting an APT are of utmost importance in attosecond physics and its applications [13,14,15] These properties can be accessed through the investigation and shaping of the XUV spectral (or equivalently temporal) phase behaviour by the simultaneous tuning of specific parameters of the intense ultrashort laser pulse that drives the high harmonic generation process [16]. The Lewenstein theory obtains the time-dependent dipole moment as t

Objectives

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Discussion

Conclusion