Bending transmission of human hair at terahertz frequency regime

Frequency, geometry and dimensional dependences of the single-mode terahertz (THz) wave transmission along a dielectric bent fiber have been investigated. The human hair shaft, which resembles a dielectric rod and thus acts as a waveguide, is used for the transmission experiment. We here show the investigations based on a computational time-domain method in order to fully interpret the experimental results of hair-guided THz wave propagation. The frequency at which the difference between the wave vectors of the incident wave and the waveguide mode is comparable to the reciprocal of the length of the hair bundle gives low bending radiation loss under whole-body irradiation condition due to the maximized coupling coefficient.