Review of the structure and processing-defect-property relationships of potassium titanyl phosphate: A strategy for novel thin-film photonic devices

Potassium titanyl phosphate (KTiOPO₄ or KTP) is a premier nonlinear optical (NLO) material. KTP has a waveguide figure-of-merit which is twice that of other mixed metal oxides and is unparalleled at the doubling of Nd laser radiation near 1 μm. It has a complex high-temperature chemistry that produces a dramatic effect upon the observed nonlinear optical behavior. A summary is provided of the current knowledge of the single-crystal KTiOPO₄ structure field with specific focus on defect chemistry, structure, and processing-defect-property relationships and waveguide technology. On the basis of this summary, a strategy is proposed for the development of novel electrooptical and nonlinear optical devices based on thin-film fabrication.