Visualization and Manipulation of Terahertz Light in the Near-Field

Plasmonics is part of the fascinating field of nanophotonics, which explores how electromagnetic fields can be confined over dimensions smaller than the wavelength. Given that THz waves may be generated and detected using ultra-short laser pulses, i.e. femtosecond (fs) laser, coherent time-domain THz measurement enable direct reading of the amplitude and phase information of the electric field. Combined with this capability, exploring the electromagnetic interactions of THz waves below diffraction limit is a powerful tool to understand the plasmonic nature of light at the metal/insulator interface. Here, we summarize on the recent advances in THz microscopy based on 2-dimensional electro optic (EO) imaging using an intense THz pulse source. These recent achievements in optimizing the spatial resolution and acquisition time will drastically accelerate our comprehension of the subwavelength light-matter interactions at THz frequencies and enable, among others, new sensing applications. Our discussion will include demonstrations on field enhancement in metallic-based resonators and potential avenues using THz vortex beam.