High-resolution site selective optical spectroscopy of rare earth and transition metal defects in insulators

Focusing on Er3+ ions in stoichiometric LiNbO3 we demonstrate the applicati on of the combined excitation emission spectroscopy to defect systems with complicated multi-line spectra in insulating materials. After spectroscopic identification of the different defect types ("sites") the changes under a pplication of external perturbation (hydrostatic pressure, electric and mag netic fields) are investigated obtaining useful results about the electroni c states. As a major result it is shown that even smallest spectral changes (Delta E < 0.1 meV) can be detected site selectively. In a similar way, th e method has been applied to other defect systems. (C) 2000 Elsevier Scienc e B.V. All rights reserved.