E. Gustafsson

Design and characterization of extreme-ultraviolet broadband mirrors for attosecond science.

A novel multilayer mirror was designed and fabricated based on a recently developed three-material technology aimed both at reaching reflectivities of about 20% and at controlling dispersion over a bandwidth covering photon energies between 35 and 50 eV. The spectral phase upon reflection was retrieved by measuring interferences in a two-color ionization process using high-order harmonics produced from a titanium: sapphire laser. We demonstrate the feasibility of designing and characterizing phase-controlled broadband optics in the extreme-ultraviolet domain, which should facilitate the manipulation of attosecond pulses for applications.

Broadband attosecond pulse shaping

We present experiments on the control over spectral amplitude and phase of attosecond pulses, using metallic and semiconductor thin-film dispersive filters. A pulse duration as short as 130 as is obtained.

Short XUV pulses to characterize field-free molecular alignment

We present experiments on field-free molecular alignment of N2 and CO2 probed with short XUV pulses that are obtained via high-harmonic generation. The XUV pulses induce a dissociative ionization or a Coulomb explosion of the molecule, where the fragment ion recoil (measured using the velocity map imaging technique) provides information on the alignment of the parent molecule at the time of ionization. We discuss how photoelectron detection may in future allow the determination of molecular-frame photoelectron angular distributions and molecular structure.

Momentum shearing interferometry of electron waves

We analyse recent experiments on momentum shearing interferometry of electron wave packets by using an optical analogy with shearing interferometry for optical waves. This analogy offers a convenient point of view to discuss the capabilities and difficulties of this technique used to access the phase of electron wave packets.

Characterization of Attosecond Pulse Trains

Ultrashort light pulses, as short as 100 as, can be produced from high harmonic generation (HHG) in an atomic gas medium. This major achievement of the last 6 years in high field physics has now been demonstrated in different conditions of medium-field interaction [1].

Attosecond Dynamics of Electron Wave Packets in Intense Laser Fields

The continuous progress in the performances of light sources as well as detection techniques allows us to investigate and control the states of matter in even finer details. Light sources, ranging from the infrared (IR) to the extreme ultraviolet (XUV), are becoming increasingly coherent, intense, well characterized, and controlled. The shortest available light pulses are now significantly shorter than 1 fs [1]–[4], thus offering unique promise for studies of ultrafast electron dynamics.

Attosecond pulse trains generated in a filament

We present temporal characterization of attosecond pulse trains generated during self-guided propagation of intense pulses in a long gas target. Spectral phase jumps are observed, affecting the temporal shape of the attosecond pulse train.

Progress in attosecond technology-application to momentum shearing interferometry of electron wavepackets

The recently demonstrated momentum shearing interferometry technique, aimed at recovering phase information about electronic wave packets (EWP) will be presented. Possibilities to improve this technique will be discussed.

Atomic Physics with Attosecond Pulses

We present experimental results where attosecond pulses are generated, characterized, transported, refocused, synchronized with an IR pulse, and used in a novel application, electron wave packet interferometry.