Terahertz spectroscopy of sub-wavelength size metallic particles

The terahertz wave transmission through ensembles of sub-wavelength size metallic particles is studied by THz-TDS and finite different time domain (FDTD). The result of the experiment shows that with the increase of the thickness of the sample, the terahertz pulses experience significant attenuation, delay and broadening. In addition, an obvious red-shift and narrowing of the amplitude spectrum are observed. Numerical simulations based on FDTD are performed to explain the details of the data and lead to an excellent agreement with the experimental results. Furthermore, the relation between the size of the particles and the transmission properties of terahertz radiation is analyzed.