Dynamical visualization of anisotropic electromagnetic re-emissions from a single metal micro-helix at THz frequencies

The capability for actual measurements—not just simulations—of the dynamical behavior of THz electromagnetic waves, including interactions with prevalent 3D objects, has become increasingly important not only for developments of various THz devices, but also for reliable evaluation of electromagnetic compatibility. We have obtained real-time visualizations of the spatial evolution of THz electromagnetic waves interacting with a single metal micro-helix. After the micro-helix is stimulated by a broadband pico-second pulse of THz electromagnetic waves, two types of anisotropic re-emissions can occur following overall inductive current oscillations in the micro-helix. They propagate in orthogonally crossed directions with different THz frequency spectra. This unique radiative feature can be very useful for the development of a smart antenna with broadband multiplexing/demultiplexing ability and directional adaptivity. In this way, we have demonstrated that our advanced measurement techniques can lead to the development of novel functional THz devices.