Photoexcitation Dynamics in Dielectrics Irradiated By Ultrafast Laser Pulses

**Photoexcitation Dynamics in Dielectrics Irradiated by Ultrafast Laser Pulses**:

- Réf **ABG-132961**
- Sujet de Thèse
- 18/07/2025
- Contrat doctoral
- Laboratoire Hubert Curien
- Lieu de travail- Saint-Etienne - Auvergne-Rhône-Alpes - France
- Intitulé du sujet- Photoexcitation Dynamics in Dielectrics Irradiated by Ultrafast Laser Pulses
- Champs scientifiques- Physique
- Physique
- Sciences de l’ingénieur
- Mots clés- Simulation, Photonics, Theory, Density Function Theory, Ab initio

**Description du sujet**:
This PhD project is embedded within the broader scope of the FLASH project, which aims to predict and model structural transformations in dielectric materials irradiated by bursts of ultrafast laser pulses, with durations ranging from femtoseconds to several nanoseconds. The work focuses on two major challenges in the physics of ultrafast laser-matter interaction: (1) understanding the nonlinear absorption dynamics governed by photoexcited states, and (2) modeling the inhomogeneous thermal relaxation in porous and heterogeneous media.

The project will provide both theoretical insight and numerical tools for predicting the optical and structural evolution of photoexcited dielectrics and for benchmarking these models against ultrafast time-resolved experiments carried out at national LUMA platforms.

Scientific Objectives:
The PhD research will focus on the following main objectives:

- Modeling photoexcitation dynamics in key dielectric materials using a quantum approach (MBE) informed by high-resolution band structure and dipole moment data.
- Developing a database of optical properties (e.g., refractive index, nonlinear susceptibilities) for selected materials in both ground and photoexcited states.
- Validating theoretical predictions through comparison with time-resolved spectroscopy and imaging experiments conducted within the Ultrafast LUMA infrastructure.
- Investigating the coupling of electronic excitation and structural effects, including bandgap renormalization and transient polymorphism in irradiated porous dielectrics.

**Prise de fonction**:

- 03/11/2025

**Nature du financement**:

- Contrat doctoral

**Précisions sur le financement**:

- A 3-year fellowship is available in Laboratory Hubert Curien at University Jean Monnet of Saint-Etienne, (member of Lyon University) France.

**Présentation établissement et labo d'accueil**:

- Laboratoire Hubert Curien

The Hubert Curien laboratory is a joint research unit (UMR 5516) of the Jean Monnet University, Saint-Etienne, the National Research Center ”CNRS” and the Institut d’Optique Graduate School. It is composed of about 240 staff which makes the lab the most important research structure of Saint
- Etienne. The research activities are organized according to two scientific departments: Optics, photonics and surfaces and Computer Science, Security, Image. The research activity is structured into scientific projects within 6 main teams: Micro/Nano structuring, Materials for Optics and Photonics in Extreme Radiative Environments, Laser-matter Interaction, Image Science & computer vision, Data Intelligence and Secure Embedded Systems & Hardware Architectures.

**Site web**:
**Intitulé du doctorat**:

- Doctorat en Optique, Photonique, Laser

**Pays d'obtention du doctorat**:

- France

**Etablissement délivrant le doctorat**:

- University of Saint-Etienne

**Ecole doctorale**:

- Sciences, ingénierie, santé

Strong knowledge in quantum mechanics, solid-state physics, and optical properties of materials

Experience with numerical modeling (Python, Julia, C++) and DFT codes (VASP, Abinit, Octopus) are welcome

Familiarity with ultrafast optics or laser-matter interactions is a plus

Motivated to work in a collaborative, multidisciplinary, and experimental-theoretical environment- 15/09/2025