Abstract

Potassium titanyl phosphate (KTiOPO₄, or KTP) is a nonlinear-optical and electro-optical material that has been commonly employed in the second-harmonic generation of 532-nm coherent radiation from 1.06-μm Nd:YAG lasers. In the past, applications of KTP have sometimes been limited because of photochromie damage induced by highpower, high-repetition-rate lasers (commonly referred to as gray tracking).^1-5 Reports of the damage thresholds of KTP have varied widely as different experimental configurations and different sources of material have been investigated. Other investigations have focused on the defects responsible for the formation of gray tracks. These studies have suggested several different defects active in the gray-tracking process, including Ti³⁺, impurities, oxygen vacancies, and protons in the form of OH" ions, again depending on experimental details and source of material.^3,4,6

© 1995 Optical Society of America