Cascade of parametric instabilities in a multimode laser - art. no. 053808

We analyze analytically and experimentally a cascade of parametric instabil ities in an inhomogeneously broadened multimode laser under pump modulation . From the physical model we use a multiple-scale analysis to derive slow t ime and slow space amplitude equations, taking nonlocal coupling into accou nt. Each of the two waves appearing at the primary instability acts as a pu mp for the parametric excitation of two new traveling waves with higher wav e numbers. These predictions compare well with numerical simulations of the original laser equations and experimental results obtained with a modulate d Yb-doped fiber laser.