Mid-IR Amplification Based on a Pr³⁺: InF₃ Optical Fiber in the Range $3.8 - 4.2\ \mu \text{m}$

In this article, for the first time, to the best of our knowledge, a fiber optic amplifier, operating in the middle-infrared wavelength range, has been designed, considering a single mode fluoroindate optical fiber, doped with praseodymium. After the electromagnetic investigation of the fiber, the design of the optical amplifier has been performed via a home-made computer code solver, employing measured spectroscopical parameters. The validated code solves the rate equation and the power propagation equation of the pump, the signal, and Amplifier Spontaneous Emission noise, considering the first and second order phenomena. The designed optical amplifier is very promising, exhibiting high simulated gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{G }} = 32.6 \,{\text{dB}}$</tex-math></inline-formula> and a wide −3 dB bandwidth of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$115\ {\rm{nm}}$</tex-math></inline-formula> with noise figure <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{NF }}$</tex-math></inline-formula> = 6 dB around the central signal wavelength <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$4 {\mu \text{m}}$</tex-math></inline-formula>, for input pump power <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\mathrm{P}}_{\mathrm{p}}} = 2 \ { \text{W}}$</tex-math></inline-formula>, input signal power <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\mathrm{P}}_{\mathrm{s}}} = - 30\ {\rm{ dBm}}$</tex-math></inline-formula>, and pump wavelength <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{{{\lambda }}}_{\mathrm{p}}} = 1.55\,{\mu \text{m}}$</tex-math></inline-formula>. This work suggests that high-performance Mid-IR optical amplifier could be fabricated considering feasible fluoroindate optical fiber doped with praseodymium providing for the first time the design parameters.