Resonant terahertz reflection of periodic arrays of subwavelength metallic rectangles

We present reflection properties of terahertz pulses in periodic arrays of metallic rectangles of subwavelength dimensions. Resonant reflection is characterized by terahertz time-domain spectroscopy and is attributed to the contributions from the dipole localized surface plasmons of isolated metallic rectangles, their interactions between the rectangles, and the nonresonant direct reflection. A number of factors, including the polarization of the terahertz electric field, the shape of the metal structures, the dielectric function of the substrate, and the lattice constant of the arrays are found to influence terahertz reflection properties. The measured resonant reflectance is well fit by numerical simulations.