Fluoride glasses incorporating rare earths are proposed as integrated systems for fiber optic communications in the visible and infrared parts of the spectrum. Such devices may be obtained from rare earths in fluoride glasses in direct contact with undoped glass of the same composition without the light-emitting lanthanide. Radiative and nonradiative transitions of rare earth ions in fluoride glasses are presented and from these data the laser cross-section and laser threshold power is calculated.
"Rare Earths In Fluoride Glasses As Integrated Fiber Optics Sources", Proc. SPIE 1182, French-Israeli Workshop on Solid State Lasers, (1 December 1989); doi: 10.1117/12.981467; https://doi.org/10.1117/12.981467