Development and characterization of a hybrid titanium:sapphire/neodymium:glass multiterawatt laser system.

Abstract

The broad bandwidth of Ti:sapphire, and the high energy storage/extraction capability of Nd:glass have made it possible to develop a hybrid Ti:sapphire/Nd:glass chirped-pulse-amplification (CPA) laser system. This 400-fs laser system generates pulses with a contrast ratio of 10$\sp6$:1, and is capable of producing a focused intensity in excess of 10$\sp{19}$ W/cm$\sp2$. The plasma produced by the interaction of an intense 400-fs laser pulse with an Al solid target is studied using a time-integrated x-ray spectrometer. The temporal behavior of the keV x-ray pulse emitted from the laser-produced plasma is studied with an x-ray streak camera (with 2 ps time resolution). The characteristic of the x-ray emission strongly depends on the contrast of the laser pulse. Second harmonic generation of a 1 $\mu$m, 400-fs laser pulses is investigated for Type I and Type II conversion schemes with a KDP crystal. High conversion efficiencies (up to 80%) are obtained in the intensity range from 100-400 GW/cm$\sp2$, with no obvious damage to the crystal. In the Type II predelay scheme, a pulse shortening effect is observed and the shortest measured pulse duration is 180 fs. The experimental results generally agree with the simulations of the code MIXER.