Abstract
Rare-earth (e.g., , ) based, guided wave optical amplification in lithium niobate () integrated optic systems is a new and important addition to the field of integrated optics. The application of total site selective spectroscopy to rare-earth-doped provides the most complete spectroscopic characterization of this class of materials to date. In a previous publication we identified six spectroscopic sites in Er: using total site selective spectroscopy, two of which are cluster sites which upconvert light using nonradiative energy transfer between Er ions within a given site. In this paper site identifications are made based on a consideration of solid solution defect equations in conjunction with an experimental study of the site distribution as a function of dopant concentration (0.4–2.0 mol % Er:) and the Li/Nb ratio in the crystal. The Li/Nb ratio was altered using a vapor phase equilibration technique. Our results indicate that increasing the O content of Er: not only reduces the cluster site concentration by ∼30% but also increases the amount of light absorbed in the crystal by ∼15%. This observation is, to the best of our knowledge, the first report of post growth materials processing in rare-earth-doped to effect a change in absorption or cluster site concentration. In addition, increasing the dopant concentration increases O deficiency in Er: crystals. Simple solid solution defect model calculations agree with these experimental results. © 1996 The American Physical Society.
- Received 31 July 1995
DOI:https://doi.org/10.1103/PhysRevB.53.2334
©1996 American Physical Society