High-Energy Attosecond Laboratory

Laser sources

The laboratory is based on a Ti:sa laser system operating at 1 kHz repetition rate and delivering pulses of 5 mJ energy and 25 fs duration. The carrier-envelope phase of the system is stabilised down to 250 mrad using a two-stage feedback loop.

The pulses are compressed to 5 fs using a differentially pumped hollow core fibre compressor. The carrier-envelope phase stability and the few-cycle pulse duration are fundamental requirements for the generation of isolated attosecond pulses.

The laser pulses are also used for the development of a two-stage non-collinear optical parameter amplifier operating at a central wavelength of 1200 nm and a pulse energy of about 60 microjoules.

A frequency-resolved optical gating setup and D-scan are routinely used for temporal characterisation of the pulses.

Attosecond beamline

We can routinely generate trains of attosecond pulses and isolated attosecond pulses in the extreme ultraviolet spectral range typically from 20 to 40 eV.

The beamline can be configured for various experimental setups including attosecond time resolution optical field sampling, RABBIT experiments using attosecond pulse trains, and phase-modulated spectroscopy in the extreme ultraviolet.

The extreme ultraviolet radiation is characterised using a spectrometer consisting of a concave grating and an MCP/phosphor assembly. During the experiments, the inline spectrometer is used as a diagnostic to control the stability of the harmonic radiation.

Velocity Map Imaging Spectrometer A velocity map imaging spectrometer is used to measure the photoelectrons produced in the photoionisation process induced by the absorption of an extreme ultraviolet photon. This instrument provides energy- and angle-resolved information about the photoemission process. It can also be configured to measure the photoion produced in the photoionisation process.