A special photoinjector drive laser was developed for FLASH and PITZ (DESY) that generates trains of flat-top picosecond pulses with variable shape (including flat-top). According to simulations, an optimized pulse shape allows for optimizing the emittance of the generated electron beam.
A small emittance of the electron beam is particularly important for operation short-wavelength FELs, such as the FLASH FEL and the upcoming XFEL at DESY Hamburg.

Shape of the produced flat-top picosecond pulses

UP2: High power femtosecond laser system with shaped pulses

In a way of first experiments for adaptive pulse shaping we performed spectral phase and amlitude modification with the specific goal to reach minimal pulse duration. The pulse duration is decreased up to 20 % of the initial value from 36 fs donw to 27fs as it is cleared up with the FROG traces.

We are able to drive the pulse energy after the post amplification and compression stages up to 3.5 mJ@1 kHz by keeping the minimal pulse duration.

With a use of filamenrtary pulse shaping the pulses with duration of 8.2 fs were detected after filamentary propagation of initial 35 fs pulsesin 1.2 m long cell filled with Ar at 1 bar.4-fold compression is demonstrated with efficiency of more than 50 % for single filament output. The details could be seen here or in the following publications:

1. N.I. Zhavoronkov, “ Control of compression dynamics by spatially adjustable femtosecond filamentation”, Laser Physic Letters, v.6, Issue 11 (October 2009), p. 806-812, Published Online: Jul 14, 2009, 7:35AM

2. Nickolai Zhavoronkov “Fine control of self-compression dynamics in a femtosecond filament”, J. Opt. A: Pure Appl. Opt. v. 11, Issue 12 (December 2009), 125201

UP3: High-order harmonic beamline