Method for extracting the equivalent admittance from time-varying metasurfaces and its application to self-tuned spatiotemporal wave manipulation

With their self-tuned time-varying responses, waveform-selective metasurfaces embedded with nonlinear electronics have shown fascinating applications, including distinguishing different electromagnetic waves depending on the pulse width (PW). However, thus far they have only been realized with a spatially homogeneous scattering profile. Here, by modeling a metasurface as time-varying admittance sheets, we provide an analytical calculation method to predict the metasurface time-domain responses. This allows derivation of design specifications in the form of equivalent sheet admittance, which is useful in synthesizing a metasurface with spatiotemporal control, such as to realize a metasurface with prescribed time-dependent diffraction characteristics. As an example, based on the proposed equivalent admittance sheet modeling, we synthesize a waveform-selective Fresnel zone plate with variable focal length depending on the incoming PW. The proposed synthesis method for PW-dependent metasurfaces may be extended to designing metasurfaces with more complex spatiotemporal wave manipulation, benefiting applications such as sensing, wireless communications and signal processing.

Automated summary

By modeling a metasurface as time-varying admittance sheets, an analytical calculation method is provided to predict the metasurface time-domain responses, allowing the derivation of design specifications in the form of equivalent sheet admittance. Using this method, a waveform-selective Fresnel zone plate with variable focal length depending on the incoming pulse width is synthesized. The proposed synthesis method can be extended to design metasurfaces with more complex spatiotemporal wave manipulation, benefiting applications such as sensing, wireless communications, and signal processing.