ANALYSIS OF ERBIUM-DOPED WAVE-GUIDE AMPLIFIERS BY A FULL-VECTORIAL FINITE-ELEMENT METHOD

Erbium-doped waveguide amplifiers are analyzed by solving numerically Maxwell equations and propagation-rate equations of a homogeneous thre e-level laser medium. In these new devices, the large refractive index changes and the complex geometries of the waveguides require an elect romagnetic analysis which has to incorporate vectorial effects. A full -vectorial finite-element code is used to account for the effect of sp atial mode distributions and an iterative procedure, based on the Rung e-Kutta algorithm, allows to compute both gain and amplified spontaneo us emission spectra with standard rate-equations and propagation equat ions. The method here firstly proposed, allows to model waveguide stru ctures of practical interest and to identify an optimum configuration with regard to polarization effects on the signal gain, maximum gain, pumping efficiency and noise characteristics. Numerical results are re ported regarding rib, channel and thin-film erbium-doped silica wavegu ide amplifiers.