Time-resolved imaging of near-fields in THz antennas and direct quantitative measurement of field enhancements

We investigate the interaction between terahertz waves and resonant antennas with sub-cycle temporal and λ/100 spatial resolution. Depositing antennas on a LiNbO[subscript 3] waveguide enables non-invasive electro-optic imaging, quantitative field characterization, and direct measurement of field enhancement (up to 40-fold). The spectral response is determined over a bandwidth spanning from DC across multiple resonances, and distinct behavior is observed in the near- and far-field. The scaling of enhancement and resonant frequency with gap size and antenna length agrees well with simulations.National Science Foundation (Grant Number ECCS-0824185)United States. Office of Naval Research (Grant Number N00014-09-1-1103)United States. Air Force Office of Scientific Research (Grant Number FA9550-09-1-0708)United States. Defense Threat Reduction Agency (Sub-contract W911NF-06-2-0040)National Science Foundation (U.S.). Graduate Research Fellowship Progra