Measurement of longitudinal variation of resonant dispersion in erbium-doped fibre amplifiers

Summary form only given. A complete understanding of the factors influencing ultrashort pulse propagation in erbium doped fibre amplifiers (EDFAs) is vital to exploit potential applications in all-optical switching and signal processing. In this paper, we report an experimental technique which allows the longitudinal variation in resonant dispersion to be characterised directly. We use frequency resolved optical gating (FROG) to characterise the electric field of the optical pulses before and after propagation in the EDFA. By modelling propagation using a nonlinear Schrodinger equation (NLSE) including the effects of nonlinearity, dispersion and gain, a numerical minimisation procedure is used to directly determine the group velocity dispersion (GVD) both as a function of wavelength and distance along the EDFA.