Multiphoton excitation and high-harmonics generation in topological insulator

TL;DR

This paper develops a microscopic theory for multiphoton interactions and high-harmonics generation in the surface states of topological insulators, revealing intense high harmonic radiation under strong THz pump waves.

Contribution

It introduces a detailed microscopic model including many-body Coulomb interactions for nonlinear optical processes in topological insulators.

Findings

Multiphoton excitation of 2D massless carriers is demonstrated.

High harmonic generation occurs under moderate pump wave fields.

Numerical solutions show intense high harmonic radiation.

Abstract

Multiphoton interaction of coherent electromagnetic radiation with 2D metallic carriers confined on the surface of the 3D topological insulator is considered. A microscopic theory describing the nonlinear interaction of a strong wave and metallic carriers with many-body Coulomb interaction is developed. The set of integrodifferential equations for the interband polarization and carrier occupation distribution is solved numerically. Multiphoton excitation of Fermi-Dirac sea of 2D massless carriers is considered for a THz pump wave. It is shown that in the moderately strong pump wave field along with multiphoton interband/intraband transitions the intense radiation of high harmonics takes place.