The new PLFA facility
The PLFA facility has been launched since the last scientific council, at the very end of 2004. It provides beamtime to users since mid-2005. Thanks to its 3 stages of amplification, the last one being cryogenically cooled, PLFA provides 13mJ pulses at 1kHz with 32fs pulse duration yielding to a peak power of 0.4TW. PLFA is one of the most intense kHz lasers in France and Europe. Third and fourth harmonic generation of the 800nm pulses is also possible: 300µJ at 266nm and 20µJ at 200nm are obtained with 80fs pulse duration. Since the end of 2006, PLFA includes a phase stabilised oscillator. The objective is to study the feasibility of stabilising the absolute phase of high power systems.
For two colour pump-probe experiments, PLFA can provide pulses with quasi-continuously tunability in the visible and ultraviolet spectral ranges using two commercial Non collinear Optical Parametric Amplifiers (Topas White by LIGHT CONVERSION) pumped each with 2.5mJ of the 800nm beam. The pump pulses have to fulfil strong requirements. In particular, the pulse duration must be close to 120fs (Fourier Transformed), which is significantly longer than the usual 32fs of the pulses generated by PLFA. It is therefore necessary to reduce the spectral width of the 800nm pulses prior to amplification using the DAZZLER acousto-optic filter. In this configuration, 150µJ pulses between 550 and 675nm and 20µJ between 280 and 350nm (see fig2) have been produced. The pulse duration increases from 20fs to 30fs when the wavelength decreases from 700 to 550nm.