Metamaterial surfaces

摘要

An apparatus to modify an incident free space electromagnetic wave includes a block of an artificially structured material having an adjustable spatial distribution of electromagnetic parameters (e.g., ε, μ, η, σ, and n). A controller applies control signals to dynamically adjust the spatial distribution of electromagnetic parameters in the material to introduce a time-varying path delay d(t) in the modified electromagnetic wave relative to the incident electromagnetic wave.

主权项

1. A method, comprising:
interposing a metamaterial having a controllable index of refraction responsive to an applied field (F) in a path of an incident free space electromagnetic wave; and applying a field (F) to the metamaterial to induce a spatially varying index of refraction profile in the metamaterial and to further temporally vary the applied field and the corresponding spatially varying index of refraction profile so as to introduce a time-varying path delay d (t) in a modified electromagnetic wave relative to an incident electromagnetic wave, wherein the time-varying path delay d (t) is:
a substantially linear function of time (φ(t)≈αt) so that the modified electromagnetic wave has its frequency f′ shifted relative to a frequency f of the incident electromagnetic wave by an amount δf (=α/2π); ora substantially quadratic function of time (d(t)≈αt2+βt+γ0) over a time interval substantially larger than a cycle (1/f) of the incident electromagnetic wave.