Speaker
Description
Delving the rich dynamics of many-body quantum systems represents a profound challenge in both fundamental and applied science. This challenge arises due to the intricate correlation between carriers and nuclei, which entails complex dynamic processes occurring across timescales ranging from attoseconds to picoseconds. These processes include electronic and structural phase transitions, Mott physics, and exciton dynamics. While conventional time-stationary spectroscopic methods offer valuable insights, they often lack the necessary temporal resolution to fully understand these rapid processes, emphasising the need for alternative techniques capable of capturing ultrafast dynamics.
In recent strides, the efficacy of time-resolved pump-probe inquiries employing coherent attosecond soft X-ray core-level spectroscopy has been brought to light. Soft X-ray core-level spectroscopy allows for an element-specific exploration of electronic structures in condensed matter physics. Moreover, it boasts exceptional experimental resolution, achieved by seamlessly integrating attosecond coherent ultra-broadband X-ray probe pulses with optically synchronised, carrier-envelope-phase (CEP) stable pump pulses.
The attosecond soft X-ray approach overcomes the typical time-energy uncertainty of the pump-probe intensity measurement. This way, the spectral resolution is entirely determined by the energy resolution of the spectrograph, and the temporal resolution is determined by the convolution between the attosecond soft X-ray probe pulses and the field amplitude of the CEP-stable pump pulses. This method enables unique time-energy resolutions over an ultra-broadband X-ray continuum. However, the low photon flux of the current soft X-ray sources limits the energy resolution and significantly elongates the measuring times for pump-probe time-resolved studies.
This project introduces a novel design for ultrafast shortwave infrared lasers, developing a high-energy CEP-stable Optical Parametric Chirped Pulse Amplification (OPCPA) system, offering an alternative solution to the typical Ti: Sa pumped TOPAS systems. For this purpose, the Dira 200-1 model from TRUMPF Inc. with thin-disc technology delivering 200 mJ pulses at 1 kHz is employed. The front-end we present here is comprised in a footprint of 1.2 m x 0.5 m, includes pulse compression from 650 fs to 9 fs at a 1 µm wavelength, 2.1 µm CEP-stable pulse generation via IP-DFG, and pulse amplification to microjoule energy levels in an OPCPA stage. With this configuration, our goal is to augment the pulse energy of conventional ultrafast shortwave infrared sources by more than an order of magnitude at 1 kHz while preserving the compactness and stability inherent to typical OPCPA systems. Such enhancement is pivotal in generating coherent soft-X-ray radiation boasting unparalleled photon flux within a tabletop setup and consequently reducing pump-probe acquisition times from day-long endeavours to mere minutes. Moreover, with our soft X-ray beamline design we expect to access the iron L3 edge at 710 eV for the first time employing a coherent tabletop X-ray source.
