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 application 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 application of external perturbation (hydrostatic pressure, electric and magnetic fields) are investigated obtaining useful results about the electronic 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, the method has been applied to other defect systems. (C) 2000 Elsevier Science B.V. All rights reserved.