Design, Simulation, and Characterization of MEMS-Based Slot Waveguides

This contribution presents a design approach as well as characterization results for dielectric slot waveguides fabricated in highly resistive (HR) silicon (HR-Si) designed for operation in the terahertz (THz) frequency range. The authors discuss the fundamentals of dielectric slot waveguides and the respective figures of merit. Furthermore, analytical solutions as well as numerical results from field simulations of the propagating mode are presented and discussed. Prototypes are fabricated in a process for HR-Si microelectromechanical systems (MEMSs), including a silicon-based metamaterial to mechanically support the waveguide while preserving a strong field confinement. In addition, actuator concepts to implement device functionalities, such as phase shifting capabilities, are demonstrated. The prototypes are measured and characterized using vector network analyzer (VNA)-based two-port measurements in the frequency range from 220 to 330 GHz. The devices are characterized in terms of their field confinement, loss, and effective mode index. For the first time, the authors report on the experimental validation of dielectric slot waveguides in this frequency range and provide values for the obtained losses.