Enhancement of pre-pulse and picosecond pedestal contrast of the petawatt J-KAREN-P laser

Abstract

We have experimentally improved the temporal contrast of the petawatt J-KAREN-P laser facility. We have investigated how the generation of pre-pulses by post-pulses changes due to the temporal overlap between the stretched pulse and the post-pulse in a chirped-pulse amplification system. We have shown that the time at which the pre-pulse is generated by the post-pulse and its shape are related to the time difference between the stretched main pulse and the post-pulse. With this investigation, we have found and identified the origins of the pre-pulses and have demonstrated the removal of most pre-pulses by eliminating the post-pulse with wedged optics. We have also demonstrated the impact of stretcher optics on the picosecond pedestal. We have realized orders of magnitude enhancement of the pedestal by improving the optical quality of a key component in the stretcher.

Beam Smoothing Based on Prism Pair for Multistep Pulse Compressor in PW Lasers

“…For the negative dispersion from the angular dispersion induced by the prism pair, the second-order dispersion GDD and the third-order dispersion TOD are simulated based on formulas ( 5) and (6), respectively. In the simulation, the apex angle of the prism is 20 • , the center wavelength is 925 nm, and the beam size is 370 × 370 mm 2 .…”

“…Consequently, it has attracted widespread attention in recent years [1][2][3][4]. Since the chirped pulse amplification (CPA) method was proposed in 1985 [5], more than 50 lasers worldwide have achieved peak powers of several hundred terawatts (TWs) and even petawatts (PWs) [6][7][8]. Several hundred PW femtosecond (PW-fs) laser systems are being developed or built in Europe (ELI-200PW [9]), Russia (XCLES-200PW [10]), the USA (OPAL-75PW [11]), and China (SEL-100PW [12]).…”

In-vacuum post-compression of optical probe pulses for relativistic plasma diagnostics

“…The experiment was carried out with the J-KAREN-P laser system [37,38] as part of a standard 4-week beam time with an additional 4 weeks for setup. The experimental setup is shown in Figure 1.…”

Spectral-temporal Measurement Capabilities of Third-order Correlators

“…For intermediate delays up to several tens of picoseconds coherent pulse distortions, broad pedestal as well as distinct pulses, generated e.g. by scattering or phase noise in stretcher systems and non-linear coupling during propagation, are the main origin of contrast degradation [22][23][24]. At larger delays, on the order of the duration of the stretched pulse and beyond, incoherent amplified spontaneous emission and pre-pulse replica from the main pulse are the prevalent cause of contrast degradation, where both can extend to many nanoseconds, related to path length in amplifiers.…”