Isomorphous Substitution In Potassium Titanyl Phosphate

Potassium titanyl phosphate (KTP) is a very important material for use in nonlinear optics. In particular, its nonlinear coefficients and refractive indices are well suited for efficient generation of the second harmonic of the 1.06μm line of the Nd:YAG laser. There is growing interest in manufacturing compact diode-pumped solid-state lasers with wavelengths in the visible region. The nonlinear crystal is a key component in these devices. Although it is possible to obtain blue radiation by sum frequency generation of the diode wavelength and 1.06μm, the non-critical point for type I phase matching for the second harmonic falls at around 990 nm. KTP is, therefore, unsuitable for obtaining wavelengths below 495 nm by second harmonic generation. There are many analogs of KTP in which any of the potassium, titanium or phosphorous are isomorphously replaced by other elements. For example, K can be replaced by Rb, Tl or NH4' and P by As. The properties of several of these compounds are known. Very little is known about the compound in which Ti is replaced by Sn. We describe the growth of a series of crystals KTi,_xSnx0PO4 from high temperature solution, and the characterization of the optical properties of these materials by powder methods.