Main Elements of Logistics

Virtually lossless self-compression of 10-mJ 3.9-um sub-100 fs pulses in bulk YAG resulting in 9-mJ 33-fs pulses is reported. Generated peak power exceeds 250 GW which is suitable for filamentation in ambient air

Path to high energy, high repetition rate tunable femtosecond ultraviolet pulse generation

We show that a combination of OPCPA and cascaded SFM can efficiently generate 100 μJ, MHz repetition rate, 50 fs, tunable pulses from 279 nm to 317 nm for seeding superconducting X-ray free electron lasers

Efficient tunable UV pulse generation from a green pumped fs-OPCPA

High energy tunable ultrafast UV pulses are of great interest for a variety of applications. These pulses are also required for high repetition rate, fully coherent UV seeded free electron lasers [1] . In the absence of proper laser gain materials, optical parametric chirped pulse amplification (OPCPA) is considered as a foremost technique to generate high power tunable ultra-short laser pulses in various spectral ranges [2] . A typical example is the broadband green pumped OPCPA system driven by frequency doubled Ytterbium based chirped pulse laser amplifiers (CPA). The excellent power scalability of the OPCPAs allows generation of multi-millijoule, few femtosecond pulses with hundreds of watts of average power harnessing high energy and repetition rate commercially available CPA pump systems [3] . The absence of proper nonlinear crystals hinders operating OPCPAs directly in the UV spectral range. Therefore, frequency doubling, tippling or quadrupling of conventional OPCPAs are the usual techniques of generating tunable UV pulses. However, these schemes suffer from the strong two-photon absorption, narrow phase matching bandwidth, and non-linear phase transfer to UV range. As a consequence, for ultra-short pulses the maximum conversion efficiency of such schemes is typically limited to below 10%, and usually accompanied by pulse compression complications

Temporal quality of post-compressed pulses at large compression factors

Post-compression of ultra-short laser pulses via self-phase modulation is routinely employed for the generation of laser pulses with optical bandwidths reaching far beyond the laser gain limitations. While high compression factors can be routinely achieved, the compressed pulses typically suffer from temporal quality degradation. We numerically and experimentally analyze the deterioration of different measures of temporal quality with increasing compression factor and show how appropriate dispersion management and cascading of the post-compression process can be employed to limit the impact of this effect. The demonstrated saturation of pulse quality degradation at large compression factors puts novel femtosecond laser architectures based on post-compressed pico- or even nanosecond laser systems in sight

Temporal quality of post-compressed pulses at large compression factors

Post-compression of ultra-short laser pulses via self-phase modulation is routinely employed for the generation of laser pulses with optical bandwidths reaching far beyond the laser gain limitations. While high compression factors can be routinely achieved, the compressed pulses typically suffer from temporal quality degradation. We numerically and experimentally analyze the deterioration of different measures of temporal quality with increasing compression factor and show how appropriate dispersion management and cascading of the post-compression process can be employed to limit the impact of this effect. The demonstrated saturation of pulse quality degradation at large compression factors puts novel femtosecond laser architectures based on post-compressed pico- or even nanosecond laser systems in sight

Ultrafast serrodyne optical frequency translator

The serrodyne principle enables an electromagnetic signal to be frequency shifted by applying a linear phase ramp in the time domain. This phenomenon has been exploited to frequency shift signals in the radiofrequency, microwave and optical regions of the electromagnetic spectrum over ranges of up to a few gigahertz, for example, to analyse the Doppler shift of radiofrequency signals for noise suppression and frequency stabilization. Here we employ this principle to shift the centre frequency of high-power femtosecond laser pulses over a range of several terahertz with the help of a nonlinear multi-pass cell. We demonstrate our method experimentally by shifting the central wavelength of a state-of-the-art 75 W frequency comb laser from 1,030 nm to 1,060 nm and to 1,000 nm. Furthermore, we experimentally show that this wavelength-shifting technique supports coherence characteristics at the few hertz-level while improving the temporal pulse quality. The technique is generally applicable to wide parameter ranges and different laser systems, enabling efficient wavelength conversion of high-power lasers to spectral regions beyond the gain bandwidth of available laser platforms