Optical Mobius symmetry in metamaterials

Abstract

We experimentally observed a new topological symmetry in optical composites, namely, metamaterials. While it is not found yet in nature materials, the electromagnetic Mo¨bius symmetry discovered in metamaterials is equivalent to the structural symmetry of a Mo¨bius strip, with the number of twists controlled by the sign change of the electromagnetic coupling between the meta-atoms. We further demonstrate that metamaterials with different coupling signs exhibit resonance frequencies that depend only on the number but not the locations of the ‘‘twists,’’ thus confirming its topological nature. The new topological symmetry found in metamaterials may enable unique functionalities in optical materials