An explicit formula for high-order sideband polarization by extreme tailoring of Feynman path integrals

TL;DR

This paper derives an explicit formula for high-order sideband polarization in semiconductors driven by combined NIR and THz fields, linking sideband amplitudes to material properties and laser parameters.

Contribution

It provides a novel explicit formula connecting sideband polarization with laser, electronic, and dephasing parameters using the saddle-point method.

Findings

Formula enables extraction of band structure information from experiments.

Connects sideband amplitudes with laser parameters and electronic properties.

Facilitates quantitative understanding of high-harmonic generation in solids.

Abstract

High-order sideband generation (HSG), as an analogue of the interband processes in high-harmonic generation (HHG) in solids, is a nonperturbative nonlinear optical phenomenon in semiconductors that are simultaneously driven by a relatively weak near-infrared (NIR) laser and a sufficiently strong terahertz (THz) field. We derive an explicit formula for sideband polarization vectors in a prototypical two-band model based on the saddle-point method. Our formula connects the sideband amplitudes with the laser-field parameters, electronic structures, and nonequilibrium dephasing rates in a highly nontrivial manner. Our results indicate the possibility of extracting information on band structures and dephasing rates from high-order sideband generation experiments with simple algebraic calculations. We also expect our approach to be useful on the quantitative understanding of the interband HHG.