RESUMEN
Temporal cleaning of high-power infrared (IR) pulses generated by a Ti:Sapphire system is demonstrated by the use of the Nonlinear Fourier Filtering (NFF) method. In a proof-of-principle experiment suppression of up to 1000 is achieved for the temporal pedestal prior to the main pulse, with a moderate (20-25%) overall throughput. This includes the same suppression ratio for the picosecond coherent pedestal in the direct vicinity of the main pulse. Based on the instantaneous, intensity-dependent and high-order switching characteristics of NFF, excellent pulse cleaning performance is observed. The efficient, high-contrast removal of the coherent pedestal from the foot of the main pulse even if its duration is shorter than 100 fs is compared with the capability of the plasma mirror technique. Calculations are also performed, supporting the experimentally observed sharp intensity dependence of the switching process, pointing out the dominant role of the ionization-based refractive index change.
RESUMEN
The present work demonstrates the performance of a von Hámos high-energy-resolution X-ray spectrometer based on a non-conventional conical Si single-crystal analyzer. The analyzer is tested with different primary and secondary X-ray sources as well as a hard X-ray sensitive CCD camera. The spectrometer setup is also characterized with ray-tracing simulations. Both experimental and simulated results affirm that the conical spectrometer can efficiently detect and resolve the two pairs of two elements (Ni and Cu) Kα X-ray emission spectroscopy (XES) peaks simultaneously, requiring a less than 2â cm-wide array on a single position-sensitive detector. The possible applications of this simple yet broad-energy-spectrum crystal spectrometer range from quickly adapting it as another probe for complex experiments at synchrotron beamlines to analyzing X-ray emission from plasma generated by ultrashort laser pulses at modern laser facilities.
RESUMEN
High order harmonics (HHG) were generated on noble gas cluster targets with different cluster sizes. The independently characterized cluster sources enabled experimental investigation of the recombination mechanism. HHG spectra were recorded for different backing pressures and gases (Ar, Xe) as a function of driver pulse ellipticity. Since the ellipticity-dependent HHG decay is essentially the same for the different gas-pressure pairs, we can conclude that the recombination process is dominated by atom-to-itself recollisions irrespective of cluster size and material.
RESUMEN
The interaction of ultra-intense laser pulses with matter opened the way to generate the shortest light pulses available nowadays in the attosecond regime. Ionized solid surfaces, also called plasma mirrors, are promising tools to enhance the potential of attosecond sources in terms of photon energy, photon number and duration especially at relativistic laser intensities. Although the production of isolated attosecond pulses and the understanding of the underlying interactions represent a fundamental step towards the realization of such sources, these are challenging and have not yet been demonstrated. Here, we present laser-waveform-dependent high-order harmonic radiation in the extreme ultraviolet spectral range supporting well-isolated attosecond pulses, and utilize spectral interferometry to understand its relativistic generation mechanism. This unique interpretation of the measured spectra provides access to unrevealed temporal and spatial properties such as spectral phase difference between attosecond pulses and field-driven plasma surface motion during the process.
RESUMEN
Recently a novel method called nonlinear Fourier-filtering was suggested for temporal and spatial cleaning of high-brightness laser pulses. In this paper experimental demonstration of the associated spatial filtering of this method and significant improvement of the temporal filtering feature are presented. The formerly found limit of ~103 for the temporal contrast improvement is identified as diffraction effects caused by the limited numerical aperture of imaging. It is shown by numerical simulation that proper apodization of the object can lead to sufficiently higher limit (>108). Using an advanced experimental arrangement the improvement of >2 orders of magnitude is experimentally verified in the ultraviolet and an indirect proof is presented that the background caused by the optical arrangement is reduced below 10-7.
RESUMEN
It is demonstrated for the first time that plasma mirrors can be successfully applied for KrF laser systems. High reflectivity up to 70% is achieved by optimization of the beam quality on the plasma mirror. The modest spectral shift and the good reflected beam quality allow its applicability for high power laser systems for which a new arrangement is suggested.
