Numerical Modeling of Mid-IR Lasers Based on Tb-Doped Chalcogenide Multicore Fibers

Mid-IR fiber lasers operating at wavelengths near 5 mu m are of great interest for many fundamental and industrial applications, but only a few experimental samples based on active chalcogenide fibers have been demonstrated so far. One of the limitations of the power of such lasers may be a fairly low fiber damage threshold. To solve this problem, we developed and numerically investigated in detail a mid-IR fiber laser at 5.3 mu m with multi-W output power pumped into the cladding at a wavelength of 2 mu m. We proposed using a Tb-doped chalcogenide multicore fiber with 25 single-mode cores arranged in a 5 x 5 square lattice as an active medium. The proposed laser design surpasses the power limit of single-core chalcogenide fibers. When simulating lasers, we specified realistic parameters of Tb-doped chalcogenide glass based on published experimental data. We performed a comprehensive theoretical analysis, studied the influence of various factors on the characteristics of generation, and found optimal system parameters and expected generation parameters.