Improving high-order harmonic yield using wavefront-controlled ultrashort laser pulses.

In this work we show that it is possible to increase the high-order harmonic yield when using wavefront-shaped laser beams. The investigation of the beam profile near the interaction region shows that the optimized beam is asymmetric and has a larger diameter. Thus, the optimized beam leads to a higher yield even if the peak intensity is lower compared to an unoptimized beam. This indicates that the wavefront of the fundamental laser beam and, accordingly, the focal profile play an important role in the efficient generation of high-order harmonic radiation.