Enhanced Liquid Sensing with 3D Printed Terahertz Photonic Crystals

Liquid sensing at THz frequencies is attractive, as it allows not only for the identification of different substances, but due to large attenuation of aqueous solutions, even small changes in concentration are detectable, making it ideal for process monitoring. The sensitivity can be further enhanced, by introducing a cavity, which holds the liquid, which also simplified the measurement as now a peak shift, height and width can be quantified. Here we present 3D printed metallic photonic crystals with standard WR3 waveguide interfaces for experimental characterization. The design of 2D hexagonal and 3D wood pile photonic crystals to optimize the sensitivity is presented. Aqueous glucose and alcohol solutions are investigated.