Design of Highly Efficient Pr3+-Doped Chalcogenide Fiber Laser

This letter describes the design of a medium infrared laser based on a double clad structure of praseodymium (Pr
³⁺
)-doped chalcogenide glass. The overlap of the emission cross sections of Pr
³⁺
in the transitions (
³
F2,
³
H6$\to $
³
H5, and
³
H5$\to $
³
H4) enables both transitions to simultaneously produce a single coherent wavelength in the range between 3.7 and $4.6~\mu \text{m}$ . A single pair fiber Bragg grating at the overlapping transition wavelengths is used to avoid fabrication complexity of a cascade pumping scheme. In addition, the proposed design takes advantages of the fact that one excited ion will radiate two photons in the overlapping transition wavelengths. In this letter, the laser performance is tested as a function of fiber length, pump power, signal wavelength, fiber background loss, and Pr
³⁺
-doped concentration. The modeling results reveal that 48% of slope efficiency could be produced when the fiber losses are about 1 dB/m.