Investigation of the chemical and physical properties of pristine, electrochromically damaged, and photochromically damaged KTiOPO4 (KTP) using surface analytical and optical spectroscopic techniques

摘要

Single-crystal KTiOPO4 (KTP) is widely used as a nonlinear optical material in optics and lasers, but it can suffer irreversible damage from intense electric and electromagnetic fields; impurities, defects, vacancies, and electron/hole transfers are probably involved. This report shows results of surface and near-surface (bulk) studies using SIMS, Rutherford backscattering, PIXE, channeling, and XRF. The electrochromic damage may occur upon reduction of Ti(sup 4+) to Ti(sup 3+) by trapping electrons passing through the ion channels. Jahn-Teller distortions and Ti(sup 3+) absorption could produce the dark macroscopi damage. The claim that Ag ions could travel through the ion channels, is discounted by the RBS and SIMS data. RBS does suggest Ti ion migration, but this is not likely, according to the KTP structure and lack of Ti ion enhancement in the white residue. The 355 nm radiation could be absorbed into the UV band edge to inititate a photochemical process (gray tracking), which could be the charge transfer from the oxide ligand to Ti(sup 4+) to create Ti(sup 3+).