Reciprocal Coupling of Surface Plasmon Polariton Modes in Plasma-Functionalized Metamaterials

When interfaced with a metamaterial, plasmas behave as a dielectric medium that can be adjusted to control of the metamaterial’s intrinsic properties. An experiment investigating the response of a corrugated-microstrip microwave filter coupled to a plasma discharge has been developed in the UCLA Plasma & Space Propulsion Laboratory. The microstrip behaves as a simple 1-D metamaterial device, capable of exciting plasmon-like surface waves along its axis. Results from this experiment suggest that these “spoof” surface plasmons can excite Surface Plasmon Polaritrons (SPPs) within the plasma discharge. Observed absorption peaks in the frequency response of the plasmonic device show strong coupling of the microstrip to these SPPs at resonance frequencies that correspond to the measured plasma electron density.