In this paper it is shown that, once a particular erbium-doped-silica photonic crystal fiber has been fabricated, the characteristic parameters obtained by means of the technique developed by the authors can be used to properly simulate the main features of optical amplifiers and lasers made of this fiber. This requires assuming that the finite size of the air-holes microstructure makes the overall passive losses per unit length to exhibit an effective dependence on the fiber length. Measurements are performed on a variety of amplifiers and lasers built with pieces of different lengths of two home-made fibers to check the simulation method. A good agreement is found between experimental and simulated results. This means that the proposed method is useful to design optimized erbium-doped photonic crystal fiber amplifiers and lasers for particular applications.