Fluidic-Integrated Dielectric Waveguide Mach–Zehnder Sensor for THz Spectroscopy

This paper presents the design, optimization, and characterization of a dielectric slot- waveguide (DSWG)-based sensor for fluid sensing applications. The sensor is inspired by the concept of a Mach-Zehnder interferometer (MZI) and utilizes high field confinement within the slot region to enhance sensitivity to permittivity changes, overcomming typical problems of other fluidic THz domain sensors. Advanced 3D-EM simulations were employed to optimize key design parameters, ensuring low loss and efficient sensing performance. Measurements with acetone, isopropanol, and butanol demonstrate the sensor's ability to distinguish fluids based on their permittivity, with notable differences in time shifts and attenuation. These results highlight the potential of DSWG-based sensors for precise and reliable THz sensing applications.