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

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.

Excitons and carriers in transient absorption and time-resolved ARPES spectroscopy: an abinitio approach

“…On the technological side, the growing interest in materials for applications to photovoltaic devices and semiconductor devices, calls for accurate modelling of the absorption process and the interaction between electrons and holes which, in turn, strongly affects carriers mobility. Many new materials, in particular layered materials such as transition metal dicalcogenides [14][15][16], and chromium or bismuth trihalide [17,18], display remarkably high binding energy for semiconductors. When studied through pump and probe experiments, such materials are often driven via laser pulses tuned resonant with such excitonic energies.…”