Design of in-band pumped dysprosium-doped ZBLAN fiber amplifier for mid-IR wavelength range

Abstract

In this paper, a fiber amplifier based on ZBLAN fiber doped with dysprosium is designed and optimized considering an in-band pumping scheme. The model is validated by comparing the simulated amplified spontaneous emission with the experimental curves reported in the literature. It allows to investigate the amplification of the signal of a continuous-wave fiber laser emitting in the wavelength range from 2.9 μm to 3.25 μm. The numerical analysis is carried out via home-made code that accurately takes into account the rate equations and the power propagation equations for the signal, pump, and amplified spontaneous emission. The finite element method (FEM) is used to calculate the modal overlap in the designed pump fiber combiner with the Dy 3+ -doped core. By employing an input pump power Pp = 5 W at the wavelength λ = 2.82 μm, a signal power Ps = 2 mW at the wavelength λ = 2.95 μm, a fiber length L = 3 m an amplifier output power of 0.5 W and an optical gain of about 24 dB are achieved. The obtained results are attractive for feasible innovative applications, e.g. the development of all-in-fiber systems. For instance, the pump and signal beams can be obtained via an Er:ZBLAN fiber laser and coupled with the dysprosium fiber through a single-mode fluoride coupler.