Ellipticity dependence of high-harmonic generation in solids originating from coupled intraband and interband dynamics

Nicolas Tancogne-Dejean,Oliver D Mücke,Franz X Kärtner,Angel Rubio

doi:10.1038/s41467-017-00764-5

Abstract

The strong ellipticity dependence of high-harmonic generation (HHG) in gases enables numerous experimental techniques that are nowadays routinely used, for instance, to create isolated attosecond pulses. Extending such techniques to solids requires a fundamental understanding of the microscopic mechanism of HHG. Here we use first-principles simulations within a time-dependent density-functional framework and show how intraband and interband mechanisms are strongly and differently affected by the ellipticity of the driving laser field. The complex interplay between intraband and interband effects can be used to tune and improve harmonic emission in solids. In particular, we show that the high-harmonic plateau can be extended by as much as 30% using a finite ellipticity of the driving field. We furthermore demonstrate the possibility to generate, from single circularly polarized drivers, circularly polarized harmonics. Our work shows that ellipticity provides an additional knob to experimentally optimize HHG in solids.

Highlights

The strong ellipticity dependence of high-harmonic generation (HHG) in gases enables numerous experimental techniques that are nowadays routinely used, for instance, to create isolated attosecond pulses
We neither account for any electronic dephasing nor propagation effects in our simulations, but we found that the recent experimental ellipticity profiles of HHG in bulk MgO are well reproduced by our theoretical description, showing the reliability of our theoretical description
In summary, we have investigated the role of ellipticity of the driving laser field on HHG from solids

Summary

Introduction

The strong ellipticity dependence of high-harmonic generation (HHG) in gases enables numerous experimental techniques that are nowadays routinely used, for instance, to create isolated attosecond pulses. Extending such techniques to solids requires a fundamental understanding of the microscopic mechanism of HHG. The ellipticity dependence of HHG was recently used to probe the molecular chirality on a sub-femtosecond electronic timescale[11] This ellipticity sensitivity has been successfully exploited in several gating schemes for the production of isolated attosecond XUV pulses, e.g., by polarization gating[12] and (generalized) double optical gating[13, 14]. The use of circularly polarized fields opens the door to producing vortex-shaped photoelectron momentum distributions[22] as well as studying spin-polarized electrons created by nonadiabatic tunneling[23,24,25,26], attosecond control of spin-resolved recollision dynamics[26, 27], and investigating ionization dynamics from atoms and molecules via angular streaking (atto-clock)[28,29,30,31] using cold target recoil ion momentum spectroscopy (COLTRIMS)

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Results

Conclusion