3D printed hollow core terahertz Bragg waveguides with defect layers for surface sensing applications

Abstract

We study 3D-printed hollow-core terahertz (THz) Bragg waveguides operating in an effectively single mode regime for resonant surface sensing applications. We demonstrate that by introducing a defect in the first layer of the Bragg reflector, thereby causing anticrossing between the dispersion relations of the core-guided mode and the defect mode, we can create a sharp transmission dip inside of the waveguide transmission bandgap. By tracking the changes in the spectral position of the narrow transmission dip, one can build a sensor which is highly sensitive to the optical properties of the defect layer. Unlike many other photonic bandgap waveguide sensors operating on a more common bulk sensing modality, the one proposed here enables a resonant surface sensing modality.