Coherent Transmission of THz Wave through Randomly Packed Subwavelength-sized Aluminium Particles

In the experiments of THz wave transmission through an ensemble of randomly packed aluminium particles with subwavelength sizes, we observed a strong dependence of the transmission on the lateral boundary conditions. Our results clearly showed that the processes of THz wave re-emitting from the disk-shaped samples were pure surface modes, and it is critically affected by properties of the side interface and the diameter of samples.