Photoinduced coherent modulation of an excitonic resonance via coupling with coherent optical phonons

TL;DR

This study demonstrates how ultrafast optical techniques combined with ab-initio calculations reveal the dynamic interaction between excitons and phonons in layered semiconductors, enabling coherent control of excitonic properties.

Contribution

It provides the first microscopic link between photoinduced excitonic energy modulation and coherent optical phonons in layered semiconductors.

Findings

Identification of spectral fingerprints of exciton-phonon coupling

Real-space tracking of atomic displacements induced by light

Demonstration of ultrafast coherent manipulation of excitonic states

Abstract

The coupling of excitons with atomic vibrations plays a pivotal role on the nonequilibrium optical properties of layered semiconductors. However, addressing the dynamical interaction between excitons and phonons represents a hard task both experimentally and theoretically. By means of time-resolved broadband optical reflectivity combined with state-of-the-art ab-initio calculations of a bismuth triiodide single crystal, we unravel the universal spectral fingerprints of exciton--phonon coupling in layered semiconductors. Furthermore, we microscopically relate a photoinduced coherent energy modulation of the excitonic resonance to coherent optical phonons, thereby tracking the extent of the photoinduced atomic displacement in real-space. Our findings represent a step forward on the road to coherent manipulation of the excitonic properties on ultrafast timescales.