Description of the thesis topic

Ultra-short sources have opened up the field to a considerable number of applications such as athermal machining, multi-photon microscopy, or X-UV generation through high harmonic generation. Among the most recent and most spectacular achievements is the acceleration of charged particules by sub-picosecond pulses focused on nanostructures. This new approach could cut the costs and the footprint of current particle accelerators and path the road to compact and affordable accelerators [1]. Still, practical applications in science, medicine or industry require average currents which are not yet within the reach of current chip devices. Substantial progress has been made in this area in recent years, fueled by a growing international collaboration of universities, national laboratories, and companies. One promising research direction is to work with a high-repetition-rate mid-infrared driver and large nanophotonic channels to maximize the average electron flux.

This research topic is one of the focuses of VISUAL, a large-scale European project (4 M€, 4 years) that aims to develop a versatile femtosecond source for biomedical imaging, micro-structuration and electron acceleration. The main objective of the VISUAL proposal is to scale up the average power of high-repetition-rate Ytterbium lasers (60 MHz, 60 W, 1 µJ/pulse, <300 fs), provide advanced modulation features (pulse on demand, burst mode) and push forward the wavelength tunability of ultrafast sources up to the thermal infrared. To achieve the defined objectives, the VISUAL consortium relies on a wide range of multi-disciplinary expertise, ranging from industrial ultrafast lasers advanced photonic crystal fiber, extreme nonlinear optics to nanophotonics and cutting-edge microscopy. The consortium covers three European countries (Poland, Germany, France) and includes both private and public partners, among which are the CNRS (France) and the Friedrich Alexander University (FAU, Erlangen, Germany). The FAU is at the forefront and birth of acceleration of electrons in nanostructures [1, 2]. The CNRS gathers three research units (PHLAM in Lille, Femto-ST in Besançon and INPHYNI in Nice) which are in charge, within VISUAL, of drawing photonics fibers and developing a high-power mid-infrared ultrafast driver for the FAU.

The research project aims to develop an infrared light source to drive the generation of ~MeV electron beams by electron acceleration in dielectric periodic structures. The expected output is a disruptive table-top source of MeV-electrons with high brightness. The research program comprises: (1) the design and the study of a mid-infrared difference-frequency generation (DFG) pumped by a VISUAL Ytterbium laser, (2) the assessment of the damage threshold of Silicon nanostructures provided by the FAU, and (3) electron acceleration experiments at FAU.

BIBLIOGRAPHY
[1] K. J. Leedle et al., “Phase-dependent laser acceleration of electrons with symmetrically driven silicon dual pillar gratings,” Opt. Lett., vol. 43, no. 9, pp. 2181–2184, 2018.
[2] T. Chlouba, et al., "Coherent nanophotonic electron accelerator." Nature 622.7983 (2023): 476-480.
[3] T. Sylvestre, et al., "Recent advances in supercontinuum generation in specialty optical fibers [Invited]," J. Opt. Soc. Am. B 38, F90-F103 (2021). [4] C. Gaida, et al., "Watt-scale super-octave mid-infrared intrapulse difference frequency generation." Light: Science & Applications 7.1 (2018): 94.
[5] N.Forget, et al., "A 100-kHz tunable femtosecond source for spectroscopy from the X-UV to the mid-IR (Conference Presentation)." Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIX. Vol. 10908. SPIE, 2019.

Work Context

The Institute of Physics of Nice (INPHYNI) is a mixed research unit (UMR 7010) affiliated with the University Côte d'Azur (UCA) and the French National Center for Scientific Research (CNRS). INPHYNI's activities are structured around three, principal axes: waves and quantum physics, photonics and nonlinear physics, complex fluids, and biophysics. Projects developed around these topics cover theoretical, fundamental, and experimental aspects as well as applications. These projects benefit especially from the support of technological platforms and technical shared services. Université Côte d'Azur (UCA) now includes 17 major academic establishments around the historic university core to create one of France's top 10 research-intensive universities. UCA was awarded the prestigious 'Initiatives of Excellence' certification label, which highlights the quality of its research and ensures that it has a high visibility international profile. The university's research strategy aims to create synergies between the research teams in order to explore new interdisciplinary areas while maintaining its level of excellence in academic fields. It is part of a coherent and ambitious site policy jointly developed with other players in the research, higher education and the socio-economic world.

The doctoral researcher will conduct his research in the "Matériaux et Systèmes Photoniques Complexes" (MSPC) group of INPHYNI, under the superrvision of Nicolas Forget (DR CNRS) et Aurélie Jullien (DR CNRS).

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.

Additional Information

Horizon Europe RIA project : VISUAL.
Project web site: https://horizon-visual.eu