Modeling of cascade lasing in Dy :: Chalcogenide glass fiber laser with efficient output at 4.5 μm

The performance of a continuous-wave Dy : GeAsGaSe chalcogenide glass fiber laser operating on the H-G(11/2) -> H-G(13/2) transition at 4.2-4.7 mu m is studied using numerical modeling. A double-clad fiber geometry is assumed, with direct pumping of the H-6(11/2) level at 1.7 mu m. It is shown that simultaneous lasing on the H-6(13/2) -> H-6(15/2) transition serves to effectively depopulate the H-6(13/2) level and significantly improve the efficiency and power scalability. A slope efficiency of 0.16 is calculated when the fiber loss is 1 dB/m. For efficient operation, it is necessary to keep the fiber loss below approximate to 5 dB/m.