Enhanced microwave transmission through a single subwavelength aperture surrounded by concentric grooves

Excitation of bound surface waves on textured metallic structures can lead to strong resonant absorption of incident radiation at frequencies determined by the surface profile. In the present study however, attention is turned to the role of the surface structure in the enhancement of transmission through a circular, subwavelength-diameter aperture. Undertaking the experiment at microwave wavelengths allows for a precision of manufacture and optimization of the surface structure that would be difficult to replicate at optical frequencies, and demonstrates that transmission enhancement may be achieved with near-perfect metals. Further, the use of a finite element method computational model to study the electromagnetic response of the sample allows for the fields associated with transmission enhancement to be examined, thereby obtaining a better understanding of the role of the surface profile in the enhancement mechanism.