Er³⁺-DOPED KTiOPO₄ WAVEGUIDE BY ION EXCHANGE. P.Q Huang and P.A. Thomas, Department of Physics, University of Warwick, Coventry CV4 7AL, U.K

Optical waveguides of Er³⁺-doped KTiOPO₄ were formed, for the first time, using an ion exchange process. Scanning electron microscopy and secondary ion mass spectroscopy have been used to study the depth distribution of the Er³⁺ ions and the morphology of the erbium doped crystal. The diffusion concentration was found to change two orders of magnitude in a depth of 8um. There was no obvious diffusion of Er³⁺ ion into KTiOPO₄ in the temperature range of 400-600deg.C. The erbium concentration and depth were improved after annealing at 800deg.C for a few minutes to four hours in crystals. Strong characteristic Er³⁺ intra-4f shell emission 1500-1600nm ⁴I_13/2 - ⁴I_15/2 was observed at 295K. Fluorescence showed a 2~6nm lifetime and was site-dependent. The polarization dependence of the emission spectra at 1508nm suggested that the KTP crystal structure was preserved in the doped layer. The experimental results obtained so far have shown a promising outlook for the development of a waveguide laser and an amplifier based on Er³⁺-doped KTP.