Abstract

We have observed and quantificd the broadband transient absorption in KDP and KD*P when these crystals are exposed to intense UV radiation. Defect sites are generated in the crystals by two-photon absorption of the UV light field. These sites, in turn, absorb light from the UV to the near-IR regions of the spectrum. The induced defects arc quantified to have 30% absorption at 532 nm for a 10-ns, 1-GW/ cm², 266-nm excitation pulse for a 0.8-cm crystal thickness. It is probable that this transient absorption is responsible for the anomalously low Nd:glass fourth-harmonic conversion efficiencies previously observed at high peak drive intensities.¹

© 1993 Optical Society of America