OPTICAL CLEANING OF CRYSTALS

摘要

The invention relates to a method for the preparation of a crystal, particularly of a lithium niobate or lithium tantalate crystal, for use in an optical component, wherein crystal impurities are present in the crystal, particularly Fe2+ ions or crystal flaws, causing a specific absorption of incident light, wherein in a first step the crystal is heated to a temperature at which the ions in the crystal are movable and result in conductivity, wherein part of the crystal is illuminated by means of an electromagnetic cleaning beam at a frequency in or near the visible frequency range in a subsequent cleaning step. Charges are optically excited by means of the cleaning beam and migrate in the crystal, wherein the charges are compensated for by the migration of ions, and can thus be fixed after cleaning. The crystal is cooled to the future operating temperature, particularly to room temperature, wherein the region previously illuminated by means of the cleaning beam forms a zone that is cleaned and thus improved for future use.