Materials for Erbium-Doped Fiber Amplifiers

Abstract

Fiber offers an extremely favorable geometry for optical devices, and fiber lasers [1] and amplifiers [2] were reported only shortly after the first bulk glass laser [3]. The choice of host composition has always been an important consideration. Silicates are the oldest and best understood glasses, and the first glass lasers used silicate compositions selected for high rare earth solubility and long lifetimes for the metastable state. The use of phosphate glass significantly improved the performance of early bulk Er3+ lasers [4] and it has become the most common host for bulk glass lasers doped with Er3+ and Nd3+. Although outstanding performance has been achieved using single-mode silica fiber, silica is a poor host for most activator ions, particularly rare earths. The influence of glass composition on the properties of Er3+ fiber amplifiers will be considered with particular emphasis placed upon silica; a more detailed discussion can be found in Ref. [5].