MODULATIONAL INSTABILITY OF 2 COUNTERPROPAGATING WAVES IN AN EXPERIMENTAL TRANSMISSION-LINE

We present experiments on the modulational instability of two counterpropagating waves, observed in an electrical transmission line. Our theoretical analysis leads to a set of two coupled nonlinear Schrödinger equations and predicts a partition of the linear spectrum into several regions with different behaviors. The unstable region, found in our previous study [Phys. Rev. E 49, 828 (1994)] for a single wave, remains here unstable, but with a much larger growth rate. Moreover, two new unstable regions appear. Our experiments on the dynamics of the waves are in good agreement with the theoretical predictions. © 1995 The American Physical Society.