RAMAN AND FT-IR SPECTROSCOPIC CHARACTERIZATION OF FLUX-GROWN KTIOPO4 AND KRBTIOPO4 NONLINEAR-OPTICAL CRYSTALS

Single crystals of KTiOPO4 (KTP) and K0.5Rb0.5TiOPO4 (KRbTP) have been grown using the slow fooling flux method. Laser Raman and FT-IR spect ra were recorded on these crystals in the frequency range 20-4000 cm(- 1). The observed Raman infrared bands are assigned to vibrations of th e PO4 tetrahedra, TiO6 octahedra, combination and overtone bands of PO 4 groups, OH- ion modes and external modes. The vibrational assignment s of PO4 and TiO6 vibrations have been approximated in terms of T-d an d O-h, symmetry species, respectively. Changes observed in the Raman a nd FT-IR spectra of KRbTiOPO4 crystals are discussed due to the presen ce of Rb ion. The vibrational data indicate that the tungsten (W6+) im purity is incorporated into the tungsten based flux grown KTP crystal at Ti4+ sites. Further,it has been observed that the presence of OH- d efects is dependent on the growth conditions, i.e. type of flux used a nd the presence of impurity.