Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1497116 | Optical Materials | 2006 | 8 Pages |
Abstract
Influence of thermal reduction on intrinsic (bipolarons), extrinsic (Er3+) defects and OHâ groups in Er:LiNbO3 crystals, which were as-grown and VTE-treated (VTE: vapor transport equilibration) before being reduced, was studied by measuring the polarised or unpolarised optical absorption in visible and near infrared regions. A wide and strong band extending from the optical absorption edge up to the infrared region and peaking around 500Â nm (â¼2.5Â eV), resulting from the absorption of reduction-induced bipolarons, is observed. Meanwhile, the thermal reduction also induces an additional, relatively much narrow absorption band around 370Â nm in a crystal whether it is Er-doped or undoped and whether it is congruent or originally VTE-treated. Both the 500Â nm and the 370Â nm bands show similar polarisation dependence. The thermal reduction treatment hardly influences Er3+ spectroscopic properties such as absorption amplitude, linewidth, peaking position and polarisation dependence. The original VTE effects on the spectroscopic properties of Er:LiNbO3 crystal are essentially retained still. The thermal reduction has a similar effect on the OHâ absorption to a strong VTE treatment: the removal of the OHâ groups contained in the crystal.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
De-Long Zhang, Rui Ma, E.Y.B. Pun,