Dynamical response of modulated Nd-doped kilometric fibre lasers

The response to pump-power modulation of Nd-doped fibre lasers with lengths in the kilometre range is reported. The timescales involved are close to those of subcritical regimes so that the transient relaxation oscillations are strongly damped. Furthermore, no competing effects (antiphase dynamics) occur between the two polarization eigenstates of the laser. Simple rate equations are shown to predict these behaviours. The experimental side of this study furnishes a definite demonstration of the importance of timescales in the dynamical properties of nonlinear and nonautonomous physical systems.