Attosecond science

Image: Optical scheme of the Parametric
Waveform Synthesizer

In this project, we are aiming to generate bright attosecond pulses tunable over the water-window and soft-X-ray region which will allow for the observation of chemical reactions on a sub-femtosecond timescale ranging from water hydrolysis to energy conversion processes.

The Attosecond Science team applies the Parametric Waveform Synthesis (PWS) technology, developed jointly with UFOX's Optical parametric synthesiser team, to the generation of attosecond pulses via high-harmonic generation (HHG) in a gas jet. In particular, we recently demonstrated the direct generation of isolated attosecond pulses by sub-cycle waveforms. Since sub-cycle waveforms can drive a single ionisation event, the HHG process can have a single recollision, leading to an isolated attosecond pulse without need for commonly used gating techniques.

Image: Experimental attosecond
streaking trace

The use of non-sinusoidal sub-cycle tailored waveforms promises both to overcome the current limitations in conversion efficiency of the HHG process and to allow a new level of control over strong field processes in general. To this end we are studying, both experimentally and theoretically, the effects related to the propagation of sub-cycle waveforms in plasmas and the optimization of the isolated attosecond pulse generation process.

We are in the process to generate bright attosecond pulses tunable over the water-window and soft-X-ray region that will allow for the observation of chemical reactions related to the small molecules like carbon, carbon oxides, water and oxygen. The addition of a visible channel to our PWS will increase the pulse energy of XUV attosecond pulses, therefore enabling XUV-attosecond-pump/soft-X-attosecond-probe experiments. Our attosecond research projects are done in collaboration with other groups in DESY, XFEL and Hamburg University.

Relevant references:
[1] G.M Rossi et al, "Sub-cycle mJ-level Parametric Waveform Synthesizer for Attosecond Science", Nature Photonics 14, (Dec 2019)
[2] Y. Yang et al, "Controlled Attosecond Pulse Generation with Tailored Optical Waveform", 22nd International Conference on Ultrafast Phenomena