Multimode rectangular cavity terahertz resonators

We present the design, fabrication, and characterization of two multimode waveguide-integrated terahertz (0.75-1.1 THz) resonators. Our first resonator has a size of 250μm × 125μm × 250μm, and our second resonator is a 250μm³ cube. We designed each resonator to be excited through a coupling neck of size 250μm × 10μm × 180μm in a 250μm × 125μm rectangular waveguide. We used a terahertz vector network analyzer to characterize these resonators. We deduced the resonant modes in our resonators with an electromagnetic solver. Our resonators can be used as terahertz notch filters and in klystron-like terahertz amplifiers.