Chromium centers in stoichiometric LiNbO3

The nature of Cr3+ center in LiNbO3 has been the subject of intense discussions in recent years. Partly, contradictory assignments of the centers resulted from intrinsic defects in the so-called congruent samples. More recently, stoichiometric samples, produced via the VTE process, have become available and show a largely reduced number of Cr sites. In this paper we present new spectroscopic data on a stoichiometric LiNbO3 :Cr3+ Sample produced using the HTTSSG process. This sample shows an even further reduced number of lines in the so-called R-line region. In addition, the study of this sample sheds new light on the origin of near infrared emission lines first discovered in LiNbO3 : Cr : Mg, which might be due to Cr3+-Nb4+ pairs. All emission lines show an unprecedented small line width, which allows high-resolution studies on this fascinating system. (C) 2000 Elsevier Science B.V. All rights reserved.