Tunable Rectification of Diffusion-Wave Fields by Spatiotemporal Metamaterials
Jiaxin Li, Zhanxiang Zhang, Guoqiang Xu, Haoran Sun, Lizhou Dai, Tianlong Li, Cheng‐Wei Qiu
Abstract
The diffusion process is the basis of many branches of science and engineering, and generally obeys reciprocity between two ports of a linear time-invariant medium. Recent research on classical wave dynamics has explored the spatiotemporal modulation to exhibit preferred directions in photons and plasmons. Here we report a distinct rectification effect on diffusion-wave fields by modulating the conductivity and observe nonreciprocal transport of charges. We experimentally create a spatiotemporal diffusion metamaterial, in which a mode transition to zero frequency is realized. A direct current component thereby emerges, showcasing a biased effect on the charge diffusion when the incident fundamental frequency is a multiple of the system modulation frequency. These results may find applications spanning a plethora of diffusive fields in general.