Polarized optical absorption of Nd3+ in KTiOPO4 crystals

The optical absorption of Nd3+ ions in KTrOPO(4) crystals grown from W-rich fluxes has been characterized in the 4.2-300 K temperature range. It has been found that the intensity of the optical absorption bands depends on the polarization state of the light (E) with regard to the crystal lattice axes (a, b, c). For E parallel to c all bands appear with maximum intensity. For E parallel to c and E parallel to b the band intensity decreases, but the spectra observed in the two configurations are inequivalent. It is suggested that several Nd centres contribute in KTP:W crystals. The segregation coefficient estimated for Nd in KTP crystals grown using W-rich flux is 5 x 10(-3), being at least one order of magnitude lower in crystals grown from KTP self-flux.