High average power ultrafast laser sources are finding an increasing number of applications, including micromachining, laser surgery, solar cell manufacturing, or photolithography. The use of rare earth-doped fibers is particularly well-suited to develop these sources for a number of reasons: immunity to thermal effects, good beam quality, potential robustness and integration of the laser. However, fiber amplifiers are limited in terms of peak power mainly because of their small transverse dimensions. This Ph. D. thesis aims at studying the amplification of femtosecond pulses in multicore fibers. Subsequent coherent combination of the cores allows the scaling of the output peak power.

The work will consist in understanding the propagation of short pulses in multicore fibers, and design and implement the recombination system. The wavefront of the beam will be controlled using a spatial light modulator. Different physical problems will be tackled, e. g. core coupling effects, non homogeneity of the fiber cores, phase and group delay stability among the cores. Furthermore, since the amplifier is based on the chirped-pulse amplification architecture, both the temporal (dispersion) and spatial phase are manipulated, and a precise characterization of both aspects, including possible spatio-temporal coupling, will be necessary.

This Ph. D. thesis is mainly in the area of experimental physics. The student will also be able to study its theoretical aspects involving laser physics, ultrafast and nonlinear optics, and participate in the interactions with other laboratories involved in this project, which is currently under evaluation at the Agence Nationale de la Recherche (French funding agency): IRCICA laboratory (Lille) for design and fabrication of the multicore fibers, XLIM (Limoges) for coherent combining, and ONERA (Palaiseau) for complex wavefront measurement and phase control systems.

LASERS group

http://www.lcf.institutoptique.fr/lcf-en/Groupes-de-recherche/Lasers

Palaiseau, with possibilities to make some short period in partner's laboratories

Engineering degree from the Institut d'Optique Graduate School, Master in Optic

Ecole Doctorale Ondes et Matières

Marc Hanna Tel : 01 64 53 34 24

Email: marc.hanna@institutoptique.fr

http://www.lcf.institutoptique.fr/lcf-en/Groupes-de-recherche/Lasers