Context : The last ten years have seen the strong rise of high energy picosecond laser systems based on ytterbium ion with average powers higher than 1 kW from fiber or solid-state lasers . This technological and scientific challenge opens the way to many application fields such as aerospace, medicine, plasma physics at a high repetition rate, long distance filamentation. Moreover, nonlinear post-compression of ytterbium systems at several hundred watts with capillaries or Herriot cells has shown a wide interest by demonstrating impressive time compression ratios  annoucing an imminent technological break with current Ti: sapphire systems at 1 kHz.
PhD subject: LEAP-HORIZON project aims to produce picosecond pulses of 1 Joule at the rate of 1 kHz (average power 1 kW). A Gaussian-mode 200W 1kHz thin disk-based regenerative amplifier is in development but these pre-amplifiers suffer from a poor spatial overlap between top-hat pump profiles and Gaussian cavity mode affecting the optical performance and requiring the use of large aperture components. An alternative way is the design of flat mode amplifiers ) but adapted to the case of Yb: YAG thin discs. This spatial beam shaping will enable a new post-compression scheme based on self-phase modulation of flats beams in thin films  or Herriot cells. The PhD work will consist in combining flat-mode thin-disk regenerative amplifier development and the postcompression :
- Design and realization of beam shaping adapted to thin-disk amplifiers.
- Realization of high-power flat-mode thin-disk Yb :YAG amplifier in different regimes (CW, ns, ps),
- Post compression by self-phase modulation in thin films or Herriot cell.
This subject has a high potential for publication in high-ranked international journals and international conference meeting insuring a high-level training in laser physics for industrial or academic R&D.
Location : Centre Lasers Intenses et Applications (CELIA), Bordeaux, France (www.celia.u-bordeaux1.fr)
Funding : full 3-years, starting on october 1st 2019
PhD supervisor : Dr Stéphane Petit (firstname.lastname@example.org, tel +33 (0)5 40 00 37 49)