Since its first report in 1998 by Ebbesen et al., the extraordinary transmission of light through an array of sub-wavelength apertures in an otherwise opaque metal film has resulted in equally-extraordinary activity in this and related phenomena in nanophotonics. In fact, as of the publication of this Focus Issue, the 1998 Ebbesen Nature paper has been referenced nearly 300 times. Given this level of activity, it comes as no surprise that multiple explanations exist as to the origin of extraordinary transmission through periodic arrays of sub-wavelength apertures (as evidenced by contributions in this Focus Issue). Even as the physical mechanisms are being investigated, we are witnessing the emergence of significant applications of these sub-wavelength structured surfaces, from their use as simple passive components to their use in electro-luminescent devices and biological sensors.
In assembling this Focus Issue, we attempted to strike a balance between theory and experiment, physics and applications, bearing in mind that the entire breadth of activity cannot be represented by a limited number of contributions. The Focus Issue starts off with contributions from L. Martin-Moreno and F. J. Garcia-Vidal, H. J. Lezec and T. Thio, and Gérard et al., which discuss physical mechanisms underlying extraordinary transmission through periodic structured surfaces. The contribution from H. Cao and A. Nahata studies the effect of aperture shape on extraordinary transmission via THz time-domain measurement, while S. Wedge and W. L. Barnes and Y. Liu and S. Blair study the transmission of incoherent light produced by photoluminescence from organic layers in proximity to periodic structured surfaces. Another important structure is the single sub-wavelength aperture surrounded by periodic annular corrugation, which is discussed in the contribution from A. Degiron and T. W. Ebbesen. The final contribution by Bakker et al. explores a new mechanism for enhanced transmission via spatially-modulated layered metallic structures.
In closing, we believe that the current state-of-the-art represents just the initial stage in the physics, engineering, and application of phenomena associated with extraordinary light transmission. We hope that this Focus Issue provides insight to researchers within as well as outside of this field of study, and helps to motivate continued progress.
Steve Blair and Ajay Nahata
University of Utah