This Colloquium analyzes the interaction of light with two-dimensional periodic arrays of particles and holes. The enhanced optical transmission observed in the latter and the presence of surface modes in patterned metal surfaces is thoroughly discussed. A review of the most significant discoveries in this area is presented first. A simple tutorial model is then formulated to capture the essential physics involved in these phenomena, while allowing analytical derivations that provide deeper insight. Comparison with more elaborated calculations is offered as well. Finally, hole arrays in plasmon-supporting metals are compared to perforated perfect conductors, thus assessing the role of plasmons in these types of structures through analytical considerations. The developments that have been made in nanophotonics areas related to plasmons in nanostructures, extraordinary optical transmission in hole arrays, complete resonant absorption and emission of light, and invisibility in structured metals are illustrated in this Colloquium in a comprehensive, tutorial fashion.

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Colloquium: Light scattering by particle and hole arrays

A new theory of Wood’s anomalies is presented which is based on a guided wave approach rather than the customary multiple scattering procedure. This approach provides both new insight and a method of calculation. It is shown that two distinct types of anomalies may exist: a Rayleigh wavelength type due to the emergence of a new spectal order at grazing angle, and a resonance type which is related to the guided complex waves supportable by the grating. A general theoretical treatment is presented which makes use of a surface reactance to take into account the standing waves in the grating grooves, and which derives the locations and detailed shapes of the anomalies. Rigorous results are obtained for a specific example; the amplitudes of all of the spectral orders are determined explicitly, and the Wood’s anomaly effects are demonstrated clearly in graphical form for a variety of cases.

A New Theory of Wood’s Anomalies on Optical Gratings

Optical biosensors that exploit surface plasmon resonance, waveguides and resonant mirrors have been used widely over the past decade to analyse biomolecular interactions. These sensors allow the determination of the affinity and kinetics of a wide variety of molecular interactions in real time, without the need for a molecular tag or label. Advances in instrumentation and experimental design have led to the increasing application of optical biosensors in many areas of drug discovery, including target identification, ligand fishing, assay development, lead selection, early ADME and manufacturing quality control. This article reviews important advances in optical-biosensor instrumentation and applications, and also highlights some exciting developments, such as highly multiplexed optical-biosensor arrays.

Optical biosensors in drug discovery.

Metallic nanostructures now play an important role in many applications. In particular, for the emerging fields of plasmonics and nanophotonics, the ability to engineer metals on nanometric scales allows the development of new devices and the study of exciting physics. This review focuses on top-down nanofabrication techniques for engineering metallic nanostructures, along with computational and experimental characterization techniques. A variety of current and emerging applications are also covered.

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Engineering metallic nanostructures for plasmonics and nanophotonics

Spontaneous, highly periodic, often permanent surface gratings or "ripples" can develop on the surface of almost any solid or liquid material illuminated by a single laser beam of sufficient intensity, under either pulsed or CW conditions. The grating periods are such that the incident laser beam is diffracted into a tangential wave which skims just along or under the illuminated surface. These spontaneously appearing surface ripples are generated by a runaway growth process analogous to stimulated Brillouin or Raman scattering or small-scale self focusing, but having many of the same properties as Wood's anomalies in diffraction gratings. Hence, it seems appropriate to refer to these spontaneous surface structures as "stimulated Wood's anomalies."

Stimulated Wood's anomalies on laser-illuminated surfaces

(1912). XXVII. Diffraction gratings with controlled groove form and abnormal distribution of intensity. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 23, No. 134, pp. 310-317.

R.W. Wood

Papers

XXVII. Diffraction gratings with controlled groove form and abnormal distribution of intensity