Description of the thesis topic

The application range of terahertz (THz) radiation, which lies between the microwave and infrared, historically encompasses astronomy, imaging, remote sensing, chemical spectroscopy, as well as linear and nonlinear condensed matter studies. For all these applications, broadband THz sources at high repetition rates are primordial. Laser-induced micro-plasmas are promising candidates for such THz sources, which can also be cheap and compact.
The objective of this thesis is to investigate the physics of laser-generated micro-plasmas and to improve our understanding of their low-frequency emissions. The problem will be approached in three ways: by simplified analytical modeling of the
local THz source, rigorous numerical simulations of the generation of the micro-plasma and its secondary emissions, and finally comparison of the theoretical results with corresponding experimental data. The proposed work is thus mainly oriented towards analytical modeling and numerical simulation. The principal numerical tools, a unidirectional pulse propagator and a Maxwell fluid code, are developed at ILM
and CELIA. The PhD student will have extended stays in both laboratories, in order to get in-depth training and contribute to the further development of these codes. At least one extended visit of the LPENS lab is foreseen, so the student can get some hands-on experience with the experiments.

Work Context

The goal of the project MicroTera funded by the French Agence nationale de la recherche (ANR) is the development and characterization of THz pulse generation from femtosecond laser-induced micro-plasmas produced in gases under tight focusing conditions. Experiments will be performed by the project partner at Laboratoire de Physique de l'Ecole Normale Supérieure (LPENS) in Paris, while theory and
numerical modeling will be carried out by CELIA and ILM. The necessary high-performance computing (HPC) resources will be made available as part of the project CNARO granted by the Grand équipement national de calcul intensif (GENCI).

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

The thematical framework of the thesis is rather broad, ranging from fundamental research in plasma physics and theoretical modeling of light matter interaction over HPC code development to very applied THz source development and optimization. The respective weights of these different aspects can be, to some extent, adjusted according to the profile of the candidate. The candidate must have advanced training in fundamental physics and/or scientific computing, with an ability to handle massively parallel simulation codes and to contribute to their development. Experience with Python, Fortran, C, or C++ and MPI or OpenMP is welcome.