Multielectron interference of intraband harmonics in solids

TL;DR

This paper introduces a multielectron interference model to explain the complex behavior of intraband high harmonic generation in solids, revealing new insights into electron dynamics and band structure effects.

Contribution

It proposes a novel multielectron interference model that explains the nonlinear optical phenomena in solid HHG and aligns well with semiconductor Bloch equation results.

Findings

Interference minima match between models and simulations

Different symmetry, phase, and amplitude in intraband harmonics

Pre-excitation pulses reveal $k$-resolved band structure effects

Abstract

High harmonic generation in solids provides us compact and coherent UV sources. Our simulations illustrate abnormal harmonic yield dependence on the intensity of driving or pre-excitation pulses. A multielectron interference model is proposed to reveal the mechanism of the extreme nonlinear optical phenomena. We find that the $k$-resolved intraband harmonic demonstrates different symmetry, phase, and amplitude, which can be observed by using a resonant pre-excitation pulse. The position of the interference minimum obtained by solving the semiconductor Bloch equations agrees well with that obtained by our $k$-resolved semiclassical model. This interference model can help us probe the $k$-resloved band structure and optimize the ultrafast electron-hole dynamics for solid harmonic processes.