Active metasurfaces enable dynamic manipulation of the scattered electromagnetic wavefront by spatially varying the phase and amplitude across arrays of subwavelength scatterers, imparting momentum to outgoing light. Similarly, periodic temporal modulation of active metasurfaces allows for manipulation of the output frequency of light. Here we combine spatial and temporal modulation in electrically modulated reflective metasurfaces operating at 1,530 nm to generate and diffract a spectrum of sidebands at megahertz frequencies. Temporal modulation with tailored waveforms enables the design of a spectrum of sidebands. By impressing a spatial phase gradient on the metasurface, we can diffract selected combinations of sideband frequencies. Combining active temporal and spatial variation can enable unique optical functions, such as frequency mixing, harmonic beam steering or shaping, and breaking of Lorentz reciprocity.

主动超表面通过在空间上改变亚波长散射体阵列的相位和振幅，从而为出射光赋予动量，从而实现对散射电磁波前的动态操纵。类似地，活性超表面的周期性时间调制允许操纵光的输出频率。在这里，我们将空间和时间调制结合在工作于 1,530 nm 的电调制反射超表面中，以生成并衍射兆赫频率的边带频谱。使用定制波形的时间调制可以设计边带频谱。通过在超表面上施加空间相位梯度，我们可以衍射选定的边带频率组合。结合主动的时间和空间变化可以实现独特的光学功能，例如混频、谐波光束转向或整形以及打破洛伦兹互易性。