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

Abstract

This letter 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 and utilizes high field confinement within the slot region to enhance sensitivity to permittivity changes, overcoming typical problems of other fluidic terahertz (THz) domain sensors. Advanced 3D-electromagnetic 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.