A split ring-resonator includes a substrate, an inner-trench or cavity formed into the substrate, the inner trench or cavity including a split, and an outer trench or cavity formed into the substrate around the inner trench or cavity, the outer trench or cavity including another split disposed at an opposite end of the split in the inner trench or cavity, wherein the inner trench or cavity and the outer trench or cavity are configured to receive an electrically conductive gas and/or plasma to form a split-ring resonator.