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Research axes

Principal research directions

Ultrafast Laser Processing Theory, Applications & Transfer –ULTRA (responsible R. Stoian) The ULTRA project follows an approach of research and development encompassing fundamental studies, laser applications in material processing and technology transfer. The main objectives refer to:
- Gaining access and new knowledge on laser-matter interaction mechanisms,
- Developing high throughput methods for surface and bulk 3D micro- and nano-structuring using designer ultrashort laser pulses, notably smart reconfigurable processing techniques based on pulse spatial and temporal vectorial pulse shaping.
- Developing performant investigation tools including simulation methods for probing ultrafast phenomena on surfaces and in the bulk, adaptive-predictive hydrodynamic codes and nonlinear pulse propagation approaches.
- Evaluating the possibility of industrial transfer particularly in the field of laser marking, tribology, and optics.

The emphasis lies in proposing processing tools which are matter- and shape adaptable using current laser beam engineering methods in temporal and spatial domains and adaptive, intelligent feedback loops. We are currently integrating in processing technologies pulse shaping techniques able to channel in a judicious way the energy flow in the excited matter towards optimal processing results on arbitrary patterns, as well as high efficiency parallel structuring methods. A particular interest is dedicated to 3D processing for integrated optical systems and 2D surface structuring for mechanical (tribological), microfluidics, and marking applications.

Current highlights:
- 3D refractive index control in optical glasses and embedded photonics using designer pulses.
- Real time spatial beam engineering for 2D and 3D parallel processing and corrective beam delivery.
- Micro and nanostructuring using nanoscale self-organization of matter, color coding via ripple generation, orientation and scale control.
- Control of thermodynamic evolution paths of excited matter; application in nanotechnologies (nanoparticle, nanostructuring).
- Predictive and adaptive simulation tools for describing material behaviors under laser excitation.

Laser ablation for material transfer –LMT (responsible F. Garrelie) Laser ablation and generation of ejecta is the fundament of laser-initiated matter transfer between a source of material and a collector, as typically met in transfer and deposition applications. The main topic of the LMT project is related to pulse laser deposition techniques on various timescales for elaborating materials as films and coatings with complex architectures. The emphasis is put on forming DLC and doped DLC materials, smooth or nano-structured films for sensing applications, notably in thermo-calorimetric or chemical sensing applications, with a new development towards oxide narrow band-gap materials. The accent is set on laser ablation control for optimizing or, furthermore, tailoring the properties of the deposited materials, as these are defined by the chemical and energetic characteristics of the ejecta. A new initiative relates to using adaptive pulse shaping techniques for controlling excitation and the subsequent generation of ablation products in terms of excited atoms, ions, or clusters and nanoparticles. A particular interest, shared between the LMT and ULTRA projects is related to surface nanostructuring using laser-induced self-organization of excited matter on regular patterns (ripples).

Current highlights:
- Process optimization in pulsed laser deposition via optical and spectroscopic feedback.

Materials for Optics and Photonics in Extreme Radiative Environments –MOPERE (responsible Y. Ouerdane) Energetic radiation can produce structural and electronic distortions in materials, localized on the scale of an atom., causing a change of the optical properties of the material. The MOPERE project focuses on detecting and characterizing radiation effects in optical silica-based materials and optical fibers on atomic scales, specifically defect centers that are formed in optical devices in severe radiative environments (gamma, X, optical photons, electrons, etc.). The questions of interest are linked to the formation mechanisms and the associated relaxation dynamics using a coupled experimental/simulation approach for radiation effects in dielectrics. The approach responds to present challenges related to the emergence of new radiative environments hosting optical systems for diagnostic and control such as large power laser facilities, energy facilities, nuclear storage capacities, outer space. The main objective is related to understanding how optical components, particularly optical fibers, degrade in harsh environments and to propose efficient material or system architectures (composition, structure) able to resists to physical constraints and prolonging therefore their service lifetime. The activity is largely based on in-situ and ex-situ spectroscopic studies (optical absorption, Raman scattering, photoluminescence and spin resonance)) on samples with designed composition, accompanied by multiscale models for simulating the response of silicates under irradiation.

Current highlights:
- Ab-initio simulation of point defects in various silica-based materials and the associated optical properties.
- Increasing lifetime of optical fibers subject to high cumulative X-ray and neutron doses.

Modeling of Laser-Matter interaction –LaserMode (responsible T. Itina) The development of laser technologies requires a higher understanding of the intrinsic excitation and phase-transformation mechanisms in various classes of materials including metals, semiconductors, and dielectrics. The project focuses on developing multiscale approaches (atomistic, mesoscopic, hydrodynamic, kinetic) and combined models for simulating the interaction of matter and the laser radiation with the purpose of further understanding and advancing laser structuring processes. The specific interest is in evaluation the response of optical components to laser radiation, laser structuring, and laser-based nanotechnologies.

Current highlights:
- Generation of nanoscale particulates in ablation products.
- Role of shockwave generation for damping ablation rates in multipulse laser irradiation.