Design of double-clad erbium-doped holey fiber amplifier

The design of an erbium-doped, double cladding, large mode area-holey fiber (LMA-HF) amplifiers is given. An improvement of the pump power absorption is achieved by employing a suitable hexagonal shaped, microstructured, inner cladding. The electromagnetic investigation on the fiber section is performed via a finite element method (FEM) routine, while a comprehensive numerical model for Er3+-doped fiber amplifiers is implemented in a home-made computer code to evaluate the gain characteristics, it being based on the optical power propagation and the population rate equations. In the simulations, the hole configuration, the fiber section, the length, the erbium concentration, the signal and the pump input power are varied to optimize the amplifier performance. The results of the simulation suggest the following numerical values: erbium concentration, NEropt = 3 × 1024 [ions/m3], fiber length, Lopt = 49 m, pump power, Pp(0) = 3 W, signal power, Ps(0) = 100 μW, allowing to obtain optimal amplifier performance, i.e. a gain G ≅ 31 dB.