Abstract

This paper gives the state of the art of the optical and laser properties of what is now interpreted as Cr⁴⁺ and Mn⁵* active centers in crystals. The comparison of these properties shows up the similarities of these systems but also what distinguishes them. This description is analysed within the framework of the strong-field model and the ionic crystalline environment approximation. A discussion is then developed and shows the limits of this description, what justifies and remains puzzling in the present interpretation and what needs to be studied further.

© 1994 IEEE