Influence of local fields on the dynamics of four-wave mixing signals from 2D semiconductor systems

Hahn, T.; Kasprzak, J.; Machnikowski, P.; Kuhn, T.; Wigger, D.

Research article (journal) | Peer reviewed

Abstract

In recent years the physics of two-dimensional semiconductors was revived by the discovery of the class of transition metal dichalcogenides. In these systems excitons dominate the optical response in the visible range and open many perspectives for nonlinear spectroscopy. To describe the coherence and polarization dynamics of excitons after ultrafast excitation in these systems, we employ the Bloch equation model of a two-level system extended by a local field describing the exciton–exciton interaction. We calculate four-wave mixing (FWM) signals and analyze the dependence of the temporal and spectral signals as a function of the delay between the exciting pulses. Exact analytical results obtained for the case of ultrafast (δ-shaped) pulses are compared to numerical solutions obtained for finite pulse durations. If two pulses are used to generate the nonlinear signal, characteristic spectral line splittings are restricted to short delays. When considering a three-pulse excitation the line splittings, induced by the local field effect, persist for long delays. All of the found features are instructively explained within the Bloch vector picture and we show how the exciton occupation dynamics govern the different FWM signals.

Details about the publication

JournalNew Journal of Physics (New J. Phys.)
Volume23
Article number023036
StatusPublished
Release year2021
Language in which the publication is writtenEnglish
DOI10.1088/1367-2630/abdd6c
Link to the full texthttps://doi.org/10.1088/1367-2630/abdd6c
KeywordsFour-wave mixing, 2D semiconductors

Authors from the University of Münster

Hahn, Thilo
Institute of Solid State Theory
Kuhn, Tilmann
Professur für Festkörpertheorie (Prof. Kuhn)
Wigger, Daniel
Professur für Festkörpertheorie (Prof. Kuhn)