Dy3+ doped GeGaSbS fluorescent fiber at 4.4 μm for optical gas sensing: Comparison of simulation and experiment

The infrared (IR) fluorescence from Dy3+ doped Ga5Ge20Sb10S65 fibers is investigated in details in order to develop bright IR fiber sources emitting at 4.4 μm for CO2 sensing purposes. Optical sensing requires intense IR radiation to probe with accuracy gas concentrations by measuring the gas absorption. We developed a specific modeling describing the Dy3+ doped GeGaSbS fiber IR output power by simultaneously solving rate equations and propagation equations within the fibers. This modeling allows the determination of the IR fluorescence guided along the fiber as a function of the Dy3+ doping concentration, the propagation losses and the fiber geometry. The results of the simulation are successfully compared with experimental data and are further discussed in order to determine the optimal set of fiber characteristics maximizing the IR fiber output emission.