Destructive photon echo formation in six-wave mixing signals of a MoSe$_2$ monolayer

TL;DR

This paper reports the observation of a destructive photon echo in six-wave mixing signals of a MoSe₂ monolayer, revealing interference effects in nonlinear optical response with theoretical modeling.

Contribution

It introduces the first experimental observation of destructive photon echo in a monolayer transition metal dichalcogenide and provides a theoretical explanation using a local field model and Bloch vector analysis.

Findings

Observation of destructive photon echo in MoSe₂ monolayer

Excellent agreement between experiment and local field theory

Identification of interference as the origin of the effect

Abstract

Monolayers of transition metal dichalcogenides display a strong excitonic optical response. Additionally encapsulating the monolayer with hexagonal boron nitride allows to reach the limit of a purely homogeneously broadened exciton system. On such a MoSe$_{2}$-based system we perform ultrafast six-wave mixing spectroscopy and find a novel destructive photon echo effect. This process manifests as a characteristic depression of the nonlinear signal dynamics when scanning the delay between the applied laser pulses. By theoretically describing the process within a local field model we reach an excellent agreement with the experiment. We develop an effective Bloch vector representation and thereby demonstrate that the destructive photon echo stems from a destructive interference of successive repetitions of the heterodyning experiment.