David Lloyd, Department of Physics, University of Oxford, Clarendon Laboratory
High-order harmonics of a femtosecond laser are the source of choice for table-top experiments requiring high coherence and short pulse XUV and SXR light. However there is wide debate within the community centred on the issue of maximising the spectral brightness of the emission. As part of the EPSRC funded grant “Table-top femtosecond X-ray dynamical imaging”, our group in Oxford is investigating ways of optimising the harmonic flux for a given photon energy. In this talk I will present details of a simplified calculation aimed at evaluating the (relative) brightness of the harmonic emission. I will show how the results of our calculations compare to experiment in the case of multi-cycle SWIR driver pulses. Finally, I will comment on the suitability of the calculation for identifying routes toward bright, isolated attosecond pulses from high energy, few cycle driver lasers.
Fig. 1. Figure of merit dependence on spot size and pulse energy, for 42 eV emission in argon.