Observation of Disk Scattering Slab Modes Transitioning to Disk Scattering Modes on Metal–Dielectric Heterostructures in the Terahertz Waveband

It has been demonstrated that, in the terahertz (THz) waveband, disk scattering slab modes (DSSMs) can exist in a heterostructure composed of a metallic subwavelength disk array coated on one surface of a dielectric slab. By observing the THz reflection spectrum, it is found that DSSMs can exist when the slab is sufficiently thick relative to the THz pulse wavelength. These thick slab modes, namely, disk scattering modes (DSMs), can be seen as degenerated DSSMs. Based on experimental measurements and theoretical analysis via a dipole-scattering model developed here, it is shown that the features of DSMs can be tuned by changing the geometric parameters of the disk array. These results are important for the design of new THz devices, such as THz filters.