21 research outputs found
All-Optical Experimental Control of High-Harmonic Photon Energy
We generate high-order harmonics in gaseous medium with tunable photon energy
using time domain interferometry of double pulses in a non-collinear generation
geometry. The method is based on the fact that the generated harmonics inherit
certain spectral properties of the driving laser. The two temporally delayed
ultrashort laser pulses, identical in all parameters, are produced by a
custom-made split-and-delay unit utilizing wave front splitting without a
significant energy loss. The arrangement is easy to implement in any attosecond
pulse generation beamline, and is suitable for the production of an extreme
ultraviolet source with simply and quickly variable central photon energy,
useful for a broad range of applications.Comment: 6 pages, 5 figures, after peer-revie
Spectrally tunable ultrashort monochromatized extreme ultraviolet pulses at 100 kHz
We present the experimental realization of spectrally tunable, ultrashort,
quasimonochromatic extreme ultraviolet (XUV) pulses generated at 100 kHz
repetition rate in a user-oriented gas high harmonic generation (GHHG) beamline
of the Extreme Light Infrastructure - Attosecond Light Pulse Source (ELI ALPS)
facility. Versatile spectral and temporal shaping of the XUV pulses are
accomplished with a double-grating, time-delay compensated monochromator
accommodating the two composing stages in a novel, asymmetrical geometry. This
configuration supports the achievement of high monochromatic XUV flux
(2.8e10+/-0.9e10 photons/s) combined with ultrashort pulse duration (4.0+/-0.2
fs using 12.1+/-0.6 fs driving pulses) and small spot size (sub-100 um).
Focusability, spectral bandwidth, and overall photon flux of the produced
radiation were investigated covering a wide range of instrumental
configurations. Moreover, complete temporal (intensity and phase)
characterization of the few-femtosecond monochromatic XUV pulses - a goal that
is difficult to achieve by conventional reconstruction techniques - has been
realized using ptychographic algorithm on experimentally recorded XUV-IR
pump-probe traces. The presented results contribute to in-situ, time-resolved
experiments accessing direct information on the electronic structure dynamics
of novel target materials.Comment: 20 pages, 8 figure
Large Spectral Shift of Reflected Radiation From Laser Plasmas Generated by High Contrast KrF Laser Pulses
High-contrast, high-brightness ultraviolet laser system
In this paper, improved operation of a high-contrast, high-brightness ultraviolet laser system is described. The laser system is based on a conventional short-pulse dye/excimer design, modified to contain 3 KrF excimer short-pulse amplifiers and the recently developed nonlinear Fourier-filtering stage for contrast improvement. The final amplifier accepts a beam size of ~4x4 cm2, producing 100 mJ energy of short-pulses using a two-beam interferometric multiplexing setup. Temporal measurements of the output showed positively chirped pulses of ~700 fs duration, beside a focusability of ~2 times the diffraction limit. Amplified spontaneous emission—as the only source of the temporal background—results in a focused intensity contrast of >1012 in the entire temporal window. These unique parameters give access to laser-matter interaction experiments above 1019 W/cm2 intensity at 248 nm. © 2019 Optical Society of America