Influence of FBG quality on yellow Dy-doped ZBLAN fiber lasers performance

MIR cascade lasing is a solution to mitigate the negative impact of excited state absorption on the performance of yellow lasers made of ZBLAN fibers doped with Dysprosium. A low-loss cavity with nearly ideal mirror reflectivity in both yellow and MIR wavelength ranges yields optimal results, but fabricating FBGs with extremely high reflectivity remains challenging in fluoride glasses. In this work, we use our matrix-based model to provide insights into the influence of FBGs quality on the performance of yellow Dy-doped ZBLAN FLs with MIR cascade lasing. Results reveal that reducing the front mirror reflectivity at the yellow wavelength lowers the laser slope efficiency, whereas decreasing the reflectivity of the mirrors constituting the cavity for the MIR emission leads to an increase in the threshold.