STRUCTURE-PROPERTY RELATIONSHIP IN THE KTiOPO4 FAMILY OF NONLINEAR OPTICAL CRYSTALS

P.A.Thomas

Department of Physics, Warwick University, Coventry CV4 7AL, UK

In this talk, the structures and physical characteristics of the KTiOPO₄ (KTP) family of nonlinear optical crystals are reviewed. Particular emphasis is placed on the role of pseudo-symmetry in determining the structural and physical properties and the relationship between room-temperature Pnan pseudo-symmetry and the ferroelectric/paraelectric phase transition temperature is described. The behaviour of the refractive index as a function of temperature and thermal expansion of crystals of the KTP family is described and discussed in the context of current models of the thermooptic effect. Finally, the behaviour of KTP doped with the pentavalent species Nb and Ta is compared with that of undoped material and discussed in terms of potassium-vacancy defect model.