STSM by Dr. Giuseppe Sansone and Dr. Michele Devetta, Politecnico Milano and CNR-IFN Politecnico (IT) with Prof. Jens Biegert, ICFO (ES)
On July 7th, 2014 (5 days)

Temporal characterization of attosecond pulses generated by mid-IR pulses

The purpose of the STSM was to investigate the feasibility of the temporal characterization of ultrashort extreme ultraviolet radiation (XUV) generated by the process of high-order harmonic generation by mid-infrared driving pulses. By using pulsese centered around 2.0 microns, XUV photon energies up to 500 eV can be reached enabling the investigation of femtosecond and attosecond dynamics in systems characterized by resonances in the water window. In spite of its fundamental interest for biological applications, no temporal characterization of XUV radiation generated in this spectral energy range has been reported so far.

The experiment was performed at ICFO combining the expertise of the Milano group in characterization of isolated attosecond pulses and the carrier-envelop-phase stable driving pulses centered at 1.8 microns available at ICFO. The temporal characterization was based on the so called attosecond streak camera principle by measuring using a time-of-flight spectrometer the photoelectron spectra generated by the attosecond XUV radiation in the presence of an intense synchronized infrared field. A first test measurement based on the cross-correlation between the two driving pulses evidenced an excellent stability of the laser source and of the interferometric setup used for the measurement (see Figure). Preliminary indication of a sub-cycle modulation of the photoelectron spectra as a function of the relative delay between the attosecond and mid-IR pulses was obtained.


The visit will lead to future common projects between the two groups. A new application is undergoing in order to improve the quality of the streaking effect observed so far and to implement the FROG-CRAB retrieving algorithm to the acquired data. The experimental results will be included in a future publication describing, for the first time to the best of our knowledge, the characterization of XUV pulses generated by mid-IR pulses.

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