Influence of laser wavelengths and polarizations on absorption of KDP crystal

摘要

We measured the absorption of type I doubler KDP crystal at different laser wavelengths (1064, 532 and 355 nm) by using laser induced deflection (LID) technique. We also performed the absorption measurements in the cases where beam polarization was parallel to the principal plane (Pd//Pp) and perpendicular to it (Pd⊥Pp). To account for the experiment results, a model based on crystal dichroism was developed to calculate the absorption coefficients for O ray (α_o) and E ray (α_e) at different laser wavelengths. It is found that the dichroism is manifested especially clearly at 1064nm, but not clearly at 355nm/532nm. It implies that the absorption at 1064nm is mamly due to lattice absorption, whereas defects absorption is responsible for the absorption at 355nm/532nm.