Spoofed surface plasmon Mach-Zehnder interferometer (MZI) structure for THz bio-sensing applications

We designed and analyzed Mach-Zehnder interferometer (MZI) structure consisted of doubly-corrugated spoofed surface plasmon polariton (DC-SSPP) waveguide. In this abstract a mathematical model is used to predict the phase accumulation of THz signals travelling through each arm of the MZI with various sample loadings. HFSS simulation is performed as verification of the theoretical analysis. It is demonstrated that when compared with single-armed SSPP waveguide, the MZI structure shows significant shift of the transmission maxima and minima when different DNA samples are loaded, as well as remarkably elevated qualify factors for the transmission peaks. This structure can be potentially used in applications such as tag-free genetic molecular sensing. The highly localized E-M field at frequencies close to SSPP resonance is shown to be beneficial as it may reduce the sample amount needed without affecting the selectivity of the sensing structure.