We present a CEO-stable 1.1 kW CPA system that is designed to drive a few-cycle-generation stage (<6fs pulse duration) and a subsequent atto-second beamline at the ELI-ALPS facility in Szeged. It currently delivers >300W of average power at 100kHz repetition-rate providing <10fs pulses. The chirped-pulse-amplification system (CPA) demonstrates excellent noise properties with <220mrad of the integrated carrier-envelope-offset (CEO) noise (10Hz to 20MHz) at a pulse repetition rate of 80MHz while the relative-intensity-noise (RIN) stayed <0.3%. This is the first CEO-stable laser system at 1kW level average power.
Here we present the latest experimental results of a high-power CEP-stable FCPA system. The 16-channel FCPA runs at 0.3% RMS power stability (>9hours) delivering more than 1kW and 10mJ after the compressor at a pulse duration of 280fs. To generate 6fs pulses, stretched hollow-core fibers are being employed. We present a significant up-scaling of this technique towards an output of 5mJ, 100kHz and 6fs.
Controlled few-cycle light waveforms find numerous applications in attosecond science, most notably the production of isolated attosecond pulses in the XUV spectral region for studying ultrafast electronic processes in matter. Scaling up the pulse energy of few-cycle pulses could extend the scope of applications to even higher intensity processes, such as the generation of attosecond pulses with extreme brightness from relativistic plasma mirrors. Hollow-fiber compressors are widely used to produce few-cycle pulses with excellent spatiotemporal quality, whereby octave-spanning broadened spectra can be temporally compressed to near-single-cycle duration. In order to scale up the peak power of hollow-fiber compressors, the effective length and area mode of the fiber has to be increased proportionally, thereby requiring the use of longer waveguides with larger apertures. Thanks to an innovative design utilizing stretched flexible capillaries, we show that a stretched hollow-fiber compressor can generate pulses of TW peak power, the duration of which can be continuously tuned from the input seed laser pulse duration down to almost a single cycle (3.5fs at 750nm central wavelength) simply by increasing the gas pressure at the fiber end. The pulses are characterized online using an integrated d-scan device directly under vacuum. While the pulse duration and chirp are tuned, all other pulse characteristics, such as energy, pointing stability and focal distribution remain the same on target. This unique device makes it possible to explore the generation of high-energy attosecond XUV pulses from plasma mirrors using controllable relativistic-intensity light waveforms at 1kHz.