Terahertz transmission and sensing properties of microstructured PMMA tube waveguide.

A terahertz (THz) tube waveguide with grating structure has been designed, fabricated and characterized as a microstructure waveguide sensor. The resonance and polarization properties of this microstructured tube have been experimentally and theoretically investigated, which indicates that the grating etched on the tube surface has a remarkable modulation effect on the tube resonance and polarization dependence for THz waves. Moreover, a real-time quantitative sensing has been realized based on this tube waveguide in the THz time-domain spectroscopy system. Compared with the bare tube without grating, the grating structure strongly enhances the interaction between THz evanescent field on the tube surface and analytes, improving the sensitivity. This microstructured PMMA THz tube reveals a high sensitivity of 50GHz/μl and precision of larger than 0.125μl with a good linear relationship for THz sensing applications.