Probing the dynamics of the interaction between few-cycle laser pulses and single crystal (100) Si and GaAs near the laser-induced damage threshold

The dynamics of the laser-solid interaction with high intensity ultra-short s-polarized few-cycle pulses (FCPs) (E-photon similar to 1.65 eV) and single crystals (100) Si and GaAs (E-gap similar to 1.14 and 1.4 eV, respectivly) near the multipulse laser-induced damage threshold (LIDT) were measured using a pump-probe reflectivity technique. FCP's with central wavelength 760 nm and FWHM duration 5 fs used as both pump and probe pulses were incident at 45, and the reflectivity of each probe pulse was measured as the delay between the pump and probe pulses was varied with similar to 0.1 fs resolution. Near zero delay, the probe pulse reflectivity displayed oscillatory behavior relative to the unexcited reflectivity for both materials, with a period equal to the optical cycle (similar to 2.6 fs). For Si, the crystal orientation was varied so that the field polarization was parallel to the (010) and (011) directions, and half way in between. Significantly larger zero delay oscillations were observed for the field polarization parallel to the (011) direction compared to those for the other two directions.