Improvement in the temporal contrast in the tens of ps range of the multi-PW Apollon laser front-end.

We demonstrate the impact of the optics roughness in Öffner stretchers used in chirped pulse amplification laser chains and how it is possible to improve the temporal contrast ratio in the temporal range of 10-100 ps by adequately choosing the optical quality of the key components. Experimental demonstration has been realized in the front-end source of the multi-petawatt (PW) laser facility Apollon, resulting in an enhancement of the contrast ratio by two to three orders of magnitude.

Suppression of parasitic lasing in high energy, high repetition rate Ti:sapphire laser amplifiers.

Transverse parasitic lasing is well known for limiting the signal gain and the pulse energy that can be extracted from Ti:sapphire petawatt amplifiers. We have developed a technique for suppressing these parasitic lasing modes based on perfect refractive index-matching liquid doped with a broad-bandwidth absorber to suppress the transverse lasing while ensuring proper heat removal from the Ti:sapphire crystal. The 800 nm laser output with a bandwidth of 41 nm (FWHM) and peak energy of 22.7 J at a repetition rate of 1 Hz is demonstrated.

Design of a 10 PW (150 J/15 fs) peak power laser system with Ti:sapphire medium through spectral control.

We designed a 10 PW (150 J-15 fs) laser system based on the use of titanium-doped sapphire power amplifiers. The solution is to provide an overall compensating spectral gain narrowing and shifting technique for obtaining a controlled output spectrum.