Terahertz transmission through ensembles of subwavelength-size metallic particles

摘要

We demonstrate that terahertz radiation can coherently propagate through dense ensembles of subwavelength-size metallic particles over distances that are orders of magnitude greater than the skin depth. Collectively, the metal particle ensembles behave similar to a dispersive lossy dielectric. To fully explore this phenomenon, we investigate the effects of particle size, shape, metal type, and conductivity on the temporal characteristics of the transmitted radiation. In addition, we show that the transmission preserves the incident polarization state. Such an observation indicates that electromagnetic energy propagation across the extent of the particle ensemble is of a coherent nature. Finite difference time domain simulations of electromagnetic wave propagation in random metallic media support the experimental observations and show that electromagnetic energy transport is due to near-field plasmonic coupling between particles.