Abstract: We present the temporal evolution of the terahertz (THz) field leading to the excitation of plasmonic resonances in carbon microfibers. The field evolution is mapped in space and time for the 3/2 wavelength resonance using a subwavelength aperture THz near-field probe with an embedded THz photoconductive detector. The excitation of surface waves at the fiber tips leads to the formation of a standing wave along the fiber. Local THz time-domain spectroscopy at one of the standing wave crests shows a clear third-order resonance peak at 1.65 THz, well described by the Lorentz model. This application of the subwavelength aperture THz near-field microscopy for mode mapping and local spectroscopy demonstrates the potential of near-field methods for studies of subwavelength plasmonic THz resonators.
Oleg Mitrofanov, Irina Khromova, Thomas Siday, Robert J. Thompson, Andrey N. Ponomarev, Igal Brener, John L. Reno, 'Near-Field Spectroscopy and Imaging of Subwavelength Plasmonic Terahertz Resonators', IEEE Transactions on Terahertz Science and Technology, V.6, No. 3, pp. 382 - 388 (2016)