Speaker
Description
See the full abstract here:
http://ocs.ciemat.es/EPS2019ABS/pdf/P2.2001.pdf
Temporal contrast is a crucial parameter for high-power short-pulse laser facilities. At insufficient contrast, amplified spontaneous emission (ASE) prepulse - which is inherent to lasers based on chirped-pulse amplification scheme - can create plasma on surface of a solid target before arrival of the main pulse. This preplasma reduces coupling of the main laser pulse energy to dense target layers. Contrast influences laser-driven ion acceleration [1], Kα radiation source properties [2], higher order harmonics generation [3]. Precise determination of contrast is a challenging task. It requires measurements with dynamic range higher than 10^10 in time interval of ~10 ns with resolution of the order of the main pulse duration. A simple method for estimation of ASE prepulse energy was proposed in [4]. It is based on measuring brightness of specularly reflected from a solid target laser radiation on a scattering screen. Using this method, we investigated ASE contrast of 100 TW femtosecond laser facility before and after insertion of RG-850 saturable absorber into amplification chain. ASE intensity was also measured over delay times from -400 ps to 0 ps by a 3rd order crosscorrelator. Analysis of the images from scattering screen has shown that, in addition to ASE prepulse, contrast is affected by change of laser light absorption mechanisms at intensities 10^16...10^17 W/cm^2. This factor limits applicability of the method [4].
References
1. D.Neely et al., Appl. Phys. Lett. 89, 21502 (2006).
2. S. Fourmaux, J.C. Kieffer, Appl. Phys. B 122:162 (2016).
3. I.J. Kim et al., Journal of Opt. Soc. Of Korea 13, 15 (2009). 4. A.S. Pirozhkov et al., Appl. Phys. Lett. 94, 241102 (2009).
