Parametric small signal amplification near bifurcations [ferroelectrics]

The nonlinear dielectric properties of ferroelectrics during polarization reversal are used to amplify small periodic perturbations. The ferroelectric serves as a nonlinear capacitor in a series-resonance circuit. The inductance is a linear one. Such a series-resonance circuit is a system which offers many features of nonlinear dynamical systems. It is possible to observe different types of bifurcations (pitchfork bifurcations, period-doubling cascades and chaotic behaviour) well known from the theory of nonlinear dynamical systems. Near such bifurcations the system can amplify suitable chosen periodic perturbations. These perturbations are coupled into the system by amplitude modulation of the driving voltage. Different types of bifurcations have been investigated concerning their ability of amplifying small signals