Contents I. Introduction
Amplified spontaneous emission (ASE) sources are wideband sources of incoherent light largely used in many different fields. These sources can work in the infrared wavelength range, which allows their usage in remote sensing, pollution environmental sensing, medicine, gyroscopes, and ghost imaging [1]-[7]. ASE sources can be obtained from many different kinds of rare-earth doped glass fibers, including silica, chalcogenide, germanate, antimony, tellurite, fluorozirconate and fluorophosphate glasses [8]-[11]. Germanate glasses show interesting properties, such as high dopant solubility and high physicochemical stability [9], that make them suitable for fibers co-doped with several different rare earths. However, modeling and optimization of glasses doped with many different rare-earth ions is not trivial, because of the need to know a high number of spectroscopic parameters and to consider many rare-earth ion transitions and energy transfer phenomena.
