IRRADIATION DEFECTS IN THE IRON-DOPED LITHIUM NIOBATE CRYSTAL

Measurements of the differential optical absorption spectra and resolving techniques of the spectral peak are used to investigate the absorption spectra and its variation with radiation dosage of the coloured γ-irradiated LiNbOcrystals undoped or doped with iron, The experimental results show that in the γ-irradiated LiNbO: Fe crystals there are roomtemperature stable colored centers absorption bands and charge transfer bands in the visible and near infrared region which involve all color center absorption bands （A, B, C and D） of the γ-irradiated undoped LiNbOcrystals, and a new small color center absorption band B’ （2.45 eV） on the longer wavelength side of the B band （2.70 eV）. It is considered in this paper that the broad band near the energy position 2.60 eV is a superposed band caused by the irradiation defects of the LiNbOhost lattice, and the incorporation of iron in the LiNbOhost lattice leads to the formation of Fe-Vdipoles which serve as stable traps for the interstitia