Propagation of Terahertz Pulses on Coplanar Strip-lines on Low Permittivity Substrates and a Spectroscopy Application

The authors have investigated the propagation characteristics of the terahertz electrical pulses on the coplanar strip-lines (CPSs) made on low permittivity substrates. By the use of a commercially available plastic whose permittivity is about 2.3 in 1–3 THz, the radiation loss could be made low, and the total attenuation of about 0.2 neper/mm was achieved at 1 THz. As a result, the spectra reaching 3 THz with a dynamic range of about 60 dB were realized even after the 1 mm propagation. Using the CPS device, a spectroscopy of biotin powder is demonstrated over a frequency range up to 2 THz.