Intensity-Dependent Metasurface with Digitally Reconfigurable Distribution of Nonlinearity

摘要

Nonlinear metamaterials are of continuing interest by manipulating electromagnetic (EM) waves depending on incident intensity. Most of the existing nonlinear metamaterials rely on the interactions between superconcentrated EM fields and nonlinear substances within the resonant composites, which cannot be easily adjusted dynamically. Here, an intensity-dependent metasurface is proposed, whose nonlinearity distribution is digitally reconfigurable. Different from previous works, an active microwave detecting circuit is integrated into each particle of the metasurface as the nonlinear module, endowing reflection phase of the particle with strong dependence on microwave intensities. By controlling the circuit using a digital bit, the particle can be switched to be linear with a fixed phase, which provides a digital way to reconfigure the arrangement of nonlinear and linear particles on the metasurface. Therefore, the phase profile on the surface is determined by the incoming intensity and digital controlling signals, opening up new possibilities in nonlinear EM wave manipulations. The concept is demonstrated by the digitally defined nonlinear scattering measurements at microwave frequencies. As a new metamaterial with the digitally reconfigurable nonlinearity and negligible thickness, this proposal may find potential applications including power protection, EM compatibility, nonlinear beam scanning, and so on.