Modeling of Cascade Lasing in Dy : Chalcogenide Glass Fiber Laser With Efficient Output at 4.5 $\mu$m

The performance of a continuous-wave Dy:GeAsGaSe chalcogenide glass fiber laser operating on the
⁶
H
_11/2
rarr
⁶
H
_13/2
transition at 4.2-4.7 mum is studied using numerical modeling. A double-clad fiber geometry is assumed, with direct pumping of the
⁶
H
_11/2
level at 1.7 mum. It is shown that simultaneous lasing on the
⁶
H
_13/2
rarr
⁶
H
_15/2
transition serves to effectively depopulate the
⁶
H
_11/2
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 ap5 dB/m.