Reconstruction of ultrafast exciton dynamics with a phase-retrieval algorithm

TL;DR

This paper introduces ePIX, a phase-retrieval algorithm that reconstructs ultrafast exciton dynamics in solids without prior knowledge, enabling better understanding of exciton formation and evolution in semiconductors.

Contribution

The paper presents a novel phase-retrieval method called ePIX for reconstructing exciton dynamics without prior assumptions, advancing ultrafast solid-state physics research.

Findings

ePIX accurately reconstructs exciton properties during ultrafast processes.

The method works even when exciton dynamics occur on timescales comparable to the pump pulse.

ePIX broadens the capability to analyze early-stage exciton behavior in solids.

Abstract

The first step to gain optical control over the ultrafast processes initiated by light in solids is a correct identification of the physical mechanisms at play. Among them, exciton formation has been identified as a crucial phenomenon which deeply affects the electro-optical properties of most semiconductors and insulators of technological interest. While recent experiments based on attosecond spectroscopy techniques have demonstrated the possibility to observe the early-stage exciton dynamics, the description of the underlying exciton properties remains non-trivial. In this work we propose a new method called extended Ptychographic Iterative engine for eXcitons (ePIX), capable of reconstructing the main physical properties which determine the evolution of the quasi-particle with no prior knowledge of the exact relaxation dynamics or the pump temporal characteristics. By demonstrating its accuracy even when the exciton dynamics is comparable to the pump pulse duration, ePIX is established as a powerful approach to widen our knowledge of solid-state physics.