Terahertz Near-Field Microscopy of Metamaterials

In this work, near-field imaging of terahertz (THz)-frequency spoof surface plasmons (SSPs) supported by a variety of metal/dielectric metamaterial structures is reported. Our s-SNOM technique demonstrates deep sub-wavelength mapping of the field distribution associated with in-plane resonator modes in plasmonic dipole antennas and split ring resonator structures, as well as SSPs propagating on planar waveguide structures. Experimental results are compared with finite-element simulations and show excellent agreement. Furthermore, all-electronic coherent THz-s-SNOM has been employed to resolve the amplitude and phase images of localized plasmons in dipole antenna structures.