EXPERIMENTAL STUDIES OF NONLINEAR CONTINUOUS WAVES AND PULSES IN DISORDERED MEDIA SHOWING ANDERSON LOCALIZATION

The physics of disordered systems, involving Anderson localization, an d the physics of nonlinear systems merge for systems which are both di sordered and nonlinear. A fundamental question concerning continuous ( single frequency) wave or pulse propagation within such systems is whe ther or not Anderson localization is weakened by the nonlinearity. The oretical predictions for the answer are different for the two cases of continuous waves and pulses. For continuous waves, it is expected tha t localized eigenstates will not be affected by the introduction of no nlinearity. For nonlinear pulses the localization may or may not occur depending on the relative magnitude of the Anderson localization leng th and a characteristic ''nonlinearity'' length which describes the pu lse. We have experimentally studied two different types of disordered and nonlinear acoustic systems involving both pulsed and continuous wa ves and have obtained results which show that in all cases studied the oretical predictions are verified. [S0163-1829(98)01541-0].