Ultrafast thin-disk multipass amplifier with 720 mJ operating at kilohertz repetition rate for applications in atmospheric research.

We present an ultrafast thin-disk based multipass amplifier operating at a wavelength of 1030 nm, designed for atmospheric research in the framework of the Laser Lightning Rod project. The CPA system delivers a pulse energy of 720 mJ and a pulse duration of 920 fs at a repetition rate of 1 kHz. The 240 mJ seed pulses generated by a regenerative amplifier are amplified to the final energy in a multipass amplifier via four industrial thin-disk laser heads. The beam quality factor remains ∼ 2.1 at the output. First results on horizontal long-range filament generation are presented.

Active pump-seed-pulse synchronization for OPCPA with sub-2-fs residual timing jitter: erratum.

In the original manuscript, a residual RMS timing jitter below 2 fs between pump and seed pulses in the stabilized case was claimed. Following a reevaluation of the data, this was underestimated. Due to a rounding error in the calibration routine, a miscalculated calibration factor was extracted. By using a higher precision, the updated residual timing jitter amounts to 2.76 fs, or sub-3 fs. In this erratum, the calibration routine is briefly reviewed and Fig. 4, which presents the timing jitter in the stabilized and unstabilized case, is updated. All other results remain unaffected.

CEP-stable, sub-6 fs, 300-kHz OPCPA system with more than 15 W of average power.

We report on a CEP-stable OPCPA system reaching multi-GW peak powers at 300 kHz repetition rate. It delivers 15 W of average power, over 50 µJ of compressed pulse energy and a pulse duration below 6 fs. By implementing an additional pump-seed-synchronization, the output parameters are stabilized over hours with power fluctuations of less than 1.5%.

Active pump-seed-pulse synchronization for OPCPA with sub-2-fs residual timing jitter.

Short-pulse-pumped optical parametric chirped pulse amplification (OPCPA) requires a precise temporal overlap of the interacting pulses in the nonlinear crystal to achieve stable performance. We present active synchronization of the ps-pump pulses and the broadband seed pulses used in an OPCPA system with a residual timing jitter below 2 fs. This unprecedented stability was achieved utilizing optical parametric amplification to generate the error signal, requiring less than 4 pJ of seed- and 10 µJ of pump-pulse-energy in the optical setup. The synchronization system shows excellent long-term performance and can be easily implemented in almost any OPCPA system.

Long distance laser filamentation using Yb:YAG kHz laser.

In the framework of the Laser Lightning Rod project, whose aim is to show that laser-induced filaments can guide lightning discharges over considerable distances, we study over a distance of 140 m the filaments created by a laser system with J-range pulses of 1 ps duration at 1 kHz repetition rate. We investigate the spatial evolution of the multiple filamentation regime using the fundamental beam at 1030 nm or using combination with the second and third harmonics. The measurements were made using both a collimated beam and a loosely focused beam.