Design of a mid-IR optical fiber amplifier based on a Pr3+:InF3 glass

An optical fiber amplifier based on a fluoroindate fiber doped with praseodymium (Pr³⁺:InF₃) has been designed. The chosen fiber has a double-cladding and a 2-D shape. The electromagnetic behavior of the fiber has been simulated via a Finite Element Method (FEM) software, and the design of the fiber amplifier has been performed via a computer code, solving the rate-equations and power propagation equations. The gain G and the Amplified Spontaneous Emission (ASE) noise have been investigated as a function of different input parameters as the input signal power Ps₀, the fiber length Lfiber , and the signal wavelength λs. The simulated fiber amplifier exhibits a bandwidth BG close to BG = 100 nm around the central signal wavelength λg = 4 μm, and a gain G close to G = 30.7 dB, when an input signal power PS = 10 μW and a pump power PP = 75 mW are considered. This pump value seems particularly low and further investigation will be performed to better understand this unexpected promising value.