Growth and characterisation of RbTiOPO4 : Nb crystals as a host for rare earth ions

The growth of RbTiOPO4 crystals doped with Nb (RTP:Nb) by the Top Seeded So lution Growth (TSSG) technique is studied in order to obtain a suitable hos t for rare earths. Preliminary crystallographic and optical characterisatio ns of these crystals show that the birefringence of the crystal increases w ith Nb incorporation. while the second harmonic generation capability is pr actically unmodified with respect to RTP. Moreover, a small but significant increase in the cut-off wavelength of the UV band edge with Nb incorporati on is also found. Single crystals of RTP:Nb:Er and RTP:Nb:Yb by TSSG have b een grown and no important changes with respect to the growth of RTP:Nb hav e been observed. The concentrations of rare earths achieved are [Er3+]=0.65 x10(20) atoms.cm(-3) and [Yb3+]= 1.95X10(20) atoms cm(-3). Polarised optica l absorption spectra of Er3+ and Yb3+ in a RTP:Nb matrix are studied at 6 K and at room temperature. (C) 2001 Elsevier Science B.V. All rights reserve d.