Undoped stoichiometric LiNbO3 (SLN), Er2O3 (0.5 mol%) doped stoichiometric LiNbO3 (Er:SLN) and MgO (1.0 mol%)-Er2O3 (0.5 mol%) doped stoichiometric LiNbPO3 (Mg:Er:SLN) single crystals of 15-20 mm in diameter and 25-30 mm in length were grown by Czochralski method along the c-axis. We investigated in the UV-Vis- NIR range to study the effect of MgO and Er2O3 in the SLN host. Also, we investigated the photoluminescence (PL) properties of SLN, Er:SLN and Mg:Er:SLN. Excitation spectra for the emission from the S-4(3/2) and I-4(11/2) states in both single crystals have been studied in the range 500-700 and 1400-1700 nm. The OH- absorption band of the single crystals was investigated in the infrared by using an Fourier infrared (FT-IR) spectrophotometer at room temperature. (C) 2003 Elsevier B.V. All rights reserved.