Scaling of high harmonic generation conversion efficiency

A theory, first shown in Falcão-Filho et al (2009 Opt. Express 17 11217–29), for the calculation of high harmonic conversion efficiencies using top-hat driver pulses is presented. The theory is further extended to include dynamic ionization in each half cycle of the driver laser pulse which is crucial for the quantitative prediction of high-order harmonic efficiencies and spectra. The results are compared with numerical and experimental results from the literature for 1.6 and 2 µm drive wavelengths and good agreement is demonstrated. Particularly, it is shown that for long wavelength driver pulses, there is increased sensitivity to phase mismatch.