Multi-layer hollow-core PMMA grating tube waveguides for THz sensing applications

Abstract Multi-layer hollow-core PMMA tube waveguides with varying grating structures were theoretically and experimentally investigated for the terahertz (THz) chemical material sensor applications. Compared with single-layer tube, the multi-layer cases can produce a delayed response in the time domain with an improved extinction ratio. A double tube combination consisted of a thick double-groove chirped grating tube and a thin single-groove chirped grating one can realize an improved detection sensitivity. With different extinction ratio of the measured THz spectra, ethanol and vinegar can be distinguished with a sensitivity of about 18 dB/mL. The proposed multi-layer hollow-core grating waveguide can be further applied for the THz gas sensing applications.