Single-mode ring waveguide resonator on SAW

The recently proposed new regular electrode structure called ring waveguide resonator (RWR) on surface acoustic waves (SAW) is optimized to have a single radial mode excitation. The structure consists of a gold (Au) interdigital transducer (IDT) in the form of a ring placed on the Z-cut of aluminum nitride (AlN). The IDT itself creates a waveguide effect on the substrate. The electrical admittance of RWR as a function of frequency has a single peak corresponding to the excited radial mode. The peak has a high quality factor. The electrical admittance of RWR does not have sidelobes. The structure is evaluated by 3D finite element method (FEM).