Photoluminescence and photothermal deflection measurements in KDP crystals for high power applications

摘要

KDP is a non linear optical crystal used for frequency conversion in high power applications. In this paper we present results of optical non-destructive measurements on different fast growth KDP crystals in order to characterize the precursors responsible for laser-induced damage. We performed two types of analysis: the first one is temporally resolved photoluminescence excited by a pulsed Nd:YAG laser at 4.66 eV and 3.49 eV (266 nm and 355 nm). The second is spatially resolved photothermal deflection pumped by a CW Argon laser at 3.53 eV (351 nm). With these two complementary techniques we highlight the presence of large scale inhomogeneities and we discriminate nano-scale defects statistically distributed in the bulk of the crystals.