Microwave surface waves supported by a tapered geometry metasurface

Spatial dependent reduction of a surface wave's group velocity is demonstrated in the microwave regime across a metasurface comprised linear array of rectangular cavities. We manipulate the surface wave dispersion through variation in cavity width to provide a spatially dependent modal index. The mode is slowed and trapped at different positions along the metasurface. This “slow-light” phenomenon is observed via local electric-field and phase measurements. The latter is shown to provide a more accurate identification of the trapping location. We discuss the reflectivity of the mode close to this point and explore the excitation of higher order surface modes.