Experimental study of harmonic generation from solid surfaces irradiated by multipicosecond laser pulses

An experimental study is presented on harmonic generation from solid surfaces using 27 ps Nd:glass laser pulses $(\ensuremath{\lambda}=1053 \mathrm{nm})$ in the intensity range of ${10}^{13}--{10}^{15} {\mathrm{W}\mathrm{}\mathrm{cm}}^{\ensuremath{-}2}.$ Second, third, and fourth harmonics emitted in the specular reflection direction showed intensity scaling exponents of 1.5, 1.8, and 3.8 for an obliquely incident p-polarized laser beam, providing a conversion efficiency of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8},$ ${10}^{\ensuremath{-}10},$ and $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}$ at ${10}^{15} {\mathrm{W}\mathrm{}\mathrm{cm}}^{\ensuremath{-}2},$ respectively. Second and third harmonic radiation generated using an s-polarized pump was about 10 and 100 times smaller, respectively, compared to that for the p-polarized laser radiation. Faraday rotation observed in the reflected fundamental radiation can explain the relative harmonic yields for the p and s polarizations of the pump beam.

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