Generation of 25-TW Femtosecond Laser Pulses at 515 nm with Extremely High Temporal Contrast

Abstract

We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a pulse duration of 120 fs. On the basis of initially ultra-high contrast seed pulses we expect a temporal intensity contrast better 10 17 200 ps before the peak of the main pulse. We analyzed the temporal intensity contrast from milliseconds to femtoseconds with a dynamic range covering more than 20 orders of magnitude. The pulses were focussed with a f/2-focussing parabola resulting in a peak intensity exceeding 10 20 W/cm 2 . The peak power and intensity are to the best of our knowledge the highest values for 515 nm-laser-pulses achieved so far.

Conceptual Design Report for the LUXE Experiment

“…First, because ξ ∝ 1/ω L , and so the second and third harmonics will have ξ values that are a half or third as large; second, because the generation of a higher harmonic involves losses in the converter crystal. For example, the conversion efficiency of a potassium dihydrogen phosphate (KDP) to 2ω L is only about 25% [164] (at the level of the intensity).…”

Temporally Resolved Intensity Contouring (TRIC) for characterization of the absolute spatio-temporal intensity distribution of a relativistic, femtosecond laser pulse

“…We note though, that if the spatial intensity distribution on target was significantly steeper, for example in the case of a perfect Gaussian pulse, this interpretation can be misleading and the transversely streaming electrons could contribute or even dominate the observes expansion front. Determining the STID in focus at high peak intensity is specially interesting in combination with plasma mirrors 16 or other nonlinear techniques 45 that aim to manipulate the laser pulse close to target. TRIC gives access to the spatial intensity distribution at energies slightly above I th .…”

“…Our interpretation of the such obtained images in the framework of TRIC yields information about the absolute STID in the focus of a high-power laser pulse. This is specially interesting in combination with plasma mirrors 31 or other nonlinear techniques 32 that aim to manipulate the laser pulse close to target. TRIC gives access to the spatial intensity distribution at energies slightly above I th .…”

Conceptual design report for the LUXE experiment

“…First, because ξ ∝ 1/ω L , and so the second and third harmonics will have ξ values that are a half or third as large; second, because the generation of a higher harmonic involves losses in the converter crystal. For example, the conversion efficiency of a potassium dihydrogen phosphate (KDP) to 2ω L is only about 25% [181] (at the level of the intensity).…”