Substrate-Integrated Hollow Waveguides for Terahertz Gas Sensing

The field for potential sensing applications in the terahertz (THz) domain (0.3-10 THz) has seen increased attention in the last years, due to the progress in the development of THz sources and detectors, and due to the manifold of large THz absorption cross-sections of molecules relevant for environmental screening and medical analysis [1]. Practical applications rely on the development of compact, fast and low-cost gas sensing systems. As an alternate solution to standard gas cells, substrate-integrated hollow waveguides (iHWGs) have been introduced in the mid-infrared range, recently [2]. iHWGs offer an excellent volume-to-optical path length ratio increasing the sensitivity of the system, while maintaining a robust device with small footprint.