Effect of Pulse Duration and Polarization on Momentum and Energy Transfer to Laser-Irradiated Targets

Abstract

Polished aluminum targets were irradiated with 1.06-μm laser pulses of 60-psec and 2.5-nsec duration and of $\pi$ and $\sigma$ polarization. The peak focused intensity was varied over the range ${10}^{14}$-${10}^{16}$W/${\mathrm{cm}}^2$. Clear evidence of resonant absorption for 60-psec pulses was obtained from target momentum measurements made with a torsion pendulum. No resonant absorption effects dependent on light polarization or angle of incidence were detected for long-pulse irradiations.