Deterministic chaos, fractal structures and other beautiful phenomena are manifestations of the nonlinear character of forces which govern our world. Besides a revolutionary change in our approach to predictability, these discoveries had great impact on technological applications. Among the most fascinating ones is the possibility to control energy flows by tuning nonlinear features of complex materials.
In the context of wave propagation trough nonlinear media, the simplest form of control would be to devise a “wave diode” in which electromagnetic or elastic waves are transmitted differently along two opposite propagation directions.
To this aim we propose to exploit distinctive nonlinear properties like multistability and resonance shifts, to achieve asymmetric wave transmission. As a refence model we considered the discret nonlinear Schrodinger equation with concentrated nonlinearities, a simplified model for layered media with suitably tailored nonlinear properties.
The attached figures are a dramatic illustration of the effect: a wavepacket coming from the left passes trough the wall (the nonlinear medium). If the wave comes from the right it is almost entirely reflected back.