Chapter 4 - Rare Earth Ions—Introductory Survey

Abstract

This chapter reviews the fundamental atomic properties of trivalent rare earth ions, their behavior in a glass matrix, and the optical properties. The optical properties of the rare earth ions underlie all the bulk and fiber lasers and amplifiers made with these ions. In addition, it examines the peculiar and unique atomic characteristics of the 4f electrons of rare earth ions and the models are developed to understand and parameterize the optical spectra of rare earth ions in crystals and glasses. Moreover, this chapter focuses on the spectroscopic fundamentals, lifetimes, and cross sections of the transitions to model the behavior of fiber amplifiers. It also introduces the McCumber theory for cross-section determination and ion–ion interaction effects that enter into play at high erbium concentrations.