Out-of-plane THz electric field enhancement in vertical nano-slit arrays

We report an out-of-plane electric field enhancement in the terahertz range, using a non-conventional planar nano-slit array. Both simulations and experiments demonstrate that the field enhancement and the transmission coefficient are comparable with those observed in a planar slit array. This novel geometry is realized using standard thin film technology and thus will open the way for many new experiments where strong out of plane THz fields are needed. The planar process allows fabrication of slits with sub-nanometer gap size.