  Metamaterials are artificially created media, which allow introducing
additional degrees of freedom into electromagnetic design by controlling
constitutive material parameters. Reconfigurable time-dependent metamaterials
can further enlarge those capabilities by introducing a temporal variable as an
additional controllable parameter. Here we demonstrate a first-of-its-kind
reconfigurable volumetric metamaterial-based scatterer, wherein the
electromagnetic properties are controlled dynamically with light. In
particular, hybridized resonances in arrays of split ring resonators give rise
to a collective mode that presents properties of artificial high-frequency
magnetism for centimeter waves. Resonant behavior of each individual ring is
controlled with a photocurrent, which allows the fast tuning of macroscopic
effective permeability. Thus, the artificial gigahertz magnon resonant
excitation within a subwavelength spherical scatterer is governed by light
intensity. Four-dimensional control over electromagnetic scattering in both
space and time opens new venues for modern applications, including wireless
communications and automotive radars to name just a few.
