One-Way Hyperbolic Metasurfaces Based on Synthetic Motion

Moving metasurfaces support-guided waves exhibiting unusual optical properties, including strong anisotropy, nonreciprocity, and hyperbolic dispersion. However, for these phenomena to be noticeable, high speeds are typically required, challenging their practical implementation. Here we show a viable route toward the realization of strongly nonreciprocal hyperbolic propagation in metasurfaces placed synthetically in motion through traveling-wave space-time modulation. In addition to nonreciprocal hyperbolic propagation, the proposed time-modulation scheme induces additional exotic opportunities for nanophotonic systems, such as efficient nonreciprocal frequency conversion and mode transfer.