Terahertz Tag Using Photonic-Crystal Slabs

To realize the concept of the Internet of Everything (IoE), which has attracted significant interest, information tags directly attached to objects constitute one of the key technologies. However, in terms of security and uniqueness, the current information tags are unsatisfactory. In this paper, we propose the use of terahertz (THz) tags, which are expected to reduce these concerns, toward future IoE applications. In place of the usual small-capacity THz tags, we propose large-capacity THz tags utilizing both frequency and spatial domains by using two-dimensional photonic-crystal slabs in a matrix. We discuss the numerical analysis of photonic-crystal slabs for THz tags; for instance, the electric fields in photonic-crystal slabs at an absorption frequency and the characteristics of photonic-crystal slabs are detailed. Finally, we describe the successful demonstration of a THz tag with a capacity of 48 bit/cm(2) in the 600-GHz band, which is almost four times the capacity of previous THz tags.