Christoph Skrobol

High energy picosecond Yb:YAG CPA system at 10 Hz repetition rate for pumping optical parametric amplifiers

We present a chirped pulse amplification (CPA) system based on diode-pumped Yb:YAG. The stretched ns-pulses are amplified and have been compressed to less than 900 fs with an energy of 200 mJ and a repetition rate of 10 Hz. This system is optically synchronized with a broadband seed laser and therefore ideally suited for pumping optical parametric chirped pulse amplification (OPCPA) stages on a ps-timescale.

Broadband amplification by picosecond OPCPA in DKDP pumped at 515 nm

On the quest towards reaching petawatt-scale peak power light pulses with few-cycle duration, optical parametric chirped pulse amplification (OPCPA) pumped on a time scale of a few picoseconds represents a very promising route. Here we present an experimental demonstration of few-ps OPCPA in DKDP, in order to experimentally verify the feasibility of the scheme. Broadband amplification was observed in the wavelength range of 830-1310 nm. The amplified spectrum supports two optical cycle pulses, at a central wavelength of ~920 nm, with a pulse duration of 6.1 fs (FWHM). The comparison of the experimental results with our numerical calculations of the OPCPA process showed good agreement. These findings confirm the reliability of our theoretical modelling, in particular with respect to the design for further amplification stages, scaling the output peak powers to the petawatt scale.

Experimental and theoretical investigation of timing jitter inside a stretcher-compressor setup

In an optically synchronized short-pulse optical-parametric chirped-pulse amplification (OPCPA) system, we observe a few-100 fs-scale timing jitter. With an active timing stabilization system slow fluctuations are removed and the timing jitter can be reduced to 100 fs standard deviation (Std). As the main source for the timing fluctuations we could identify air turbulence in the stretcher-compressor setup inside the chirped pulse amplification (CPA) pump chain. This observation is supported by theoretical investigation of group delay changes for angular deviations occurring between the parallel gratings of a compressor or stretcher, as they can be introduced by air turbulence.

Simulations of petawatt-class few-cycle optical-parametric chirped-pulse amplification, including nonlinear refractive index effects

We present three-dimensional simulations of optical-parametric chirped-pulse amplification stages for a few-cycle petawatt-class laser. The simulations take into account the effects of depletion, diffraction, walk-off, quantum noise, and the nonlinear refractive index (n(2)). In the absence of n(2) effects, we show these stages can generate 3.67J pulses supporting 4fs transform-limited pulse durations. Adding the nonlinear refractive index to the simulation, the energy output is reduced by ~11% and the bandwidth narrows by ~129nm, increasing the Fourier limit by ~17.5%.

Generation of multi-octave spanning high-energy pulses by cascaded nonlinear processes in BBO

We present the generation of optical pulses with a spectral range of 500-2400 nm and energies up to 10 µJ at 1 kHz repetition rate by cascaded second-order nonlinear interaction of few-cycle pulses in beta-barium borate (BBO). Numerical simulations with a 1D+time split-step model are performed to explain the experimental findings. The large bandwidth and smooth spectral amplitude of the resulting pulses make them an ideal seed for ultra-broadband optical parametric chirped pulse amplification and an attractive source for spectroscopic applications.

Pump-Seed Synchronization Measurements for High-Power Short-Pulse Pumped Few-Cycle OPCPA System

We present the development of an optically synchronized frontend of a high-power short-pulse pumped few-cycle OPCPA system and single shot pump-seed timing jitter measurements at the position of its first OPCPA stage.

Generation and optical parametric amplification of near-IR, few-cycle light pulses

We present different schemes for the generation of few-cycle multi-μJ light pulses in the range of 700-1400 nm together with the amplification of these pulses to several mJ in two ps-pumped optical parametric amplification stages.

Efficient generation of THz pulses with 0.4 mJ energy

THz pulses above 0.4 mJ energy were generated with 0.77% efficiency by optical rectification of 785-fs laser pulses in LiNbO3 using tilted-pulse-front pumping. The spectral peak is at about 0.2 THz, suitable for charged-particle manipulation.

Effects of nonlinear refractive index on few-cycle PW-class OPCPA

With an increasing number of large-scale petawatt class lasers being based on Optical Parametric Chirped Pulse Amplification (OPCPA) simulations of the nonlinear amplification process and its parasitics becomes an important factor. OPCPA seems ideal to amplify broad bandwidth pulses to joule-level energies, making feasible the generation of few-cycle pulses with petawatt (PW) peak powers, but pushing such limits requires accurate modeling; i.e. parasitic nonlinear processes which can adversely affect OPCPA need to be considered.

Nonlinear refractive index effects in a Petawatt class OPCPA

We present 3D OPCPA simulations including nonlinear refractive index for a PW system with 3.67 J, 4 fs transform limited pulses. Those effects reduce the energy by ∼11% and increase the Fourier limit by ∼17.5%.