UV-VIS AND IR OPTICAL-ABSORPTION PROPERTIES IN MGO DOPED LINBO3 CRYSTALS

MgO-doped LiNbO3 (MLN) single crystals were investigated in the UV-VIS and IR range to study the effect of MgO in LiNbO3 (LN) host materials . Congruent LN has an optical band edge of 3.75 eV and the band gap sh ows an MgO threshold effect in the absorption coefficient. Two kinds o f indirect transitions were revealed and one is caused by MgO incorpor ation into the LN host materials. This indirect transition also shows an MgO threshold effect for doping levels around 5 mole percentage of MgO. The absorption spectra of all compositions including pure LN, hav e a slight slope change below 2.3 eV, that may be due to the effect of defects. IR experiment showed the similar MgO threshold effect at sim ilar to 5 mole percentage of MgO.