Broadband terahertz radiation through a one-dimensional grating with a tapered slit on a high-index substrate

In this paper, we present a broadband extraordinary transmission through a one-dimensional grating at terahertz frequencies. The grating with a tapered slit is carved periodically on a high-index GaAs substrate. The material for the grating is undoped Indium Antimonide. The geometry of the tapered slit is optimized to enable the impedance matching and thus broaden the transmission at a specific incidence angle, the Brewster angle. Such grating opens several opportunities to develop ultra-thin, low-loss, and broadband terahertz metamaterial antennas and absorbers.