Electromagnetic Wave Propagation Close to Microstructures Studied by Time and Phase-Resolved THz Near-Field Imaging

We demonstrate microscopic mapping of electromagnetic waves close to metal microstructures with sub-ps temporal and sub-wavelength spatial resolution by pulsed THz near-field imaging. The inherent phase-sensitivity of this technique allows mapping wavefronts of propagating modes and the measured amplitude distributions provide information on field concentration and localization close to the structures. Using this approach we investigate wave propagation through a sub-wavelength aperture, as well as the formation of traveling and standing surface waves along a metal microwire.