Absorption and EPR spectra of KTiOPO4 crystals

The optical absorption and EPR spectra of KTiOPO4 crystals grown from tungstate and phosphate fluxes are measured. Absorption in the visible spectral region is found to be due to the formation of extrinsic (W5+, AlO44-) and intrinsic (Ti3+, PO42-) color centers owing to changes in the charge state of metal ions upon the diffusion of potassium ions caused by heat treatment or irradiation. The incorporation of tungsten ions during growth from the tungstate flux significantly reduces the laser-damage threshold of the resultant crystals.