Squeezing Light through Small Holes: Fundamentals and Applications

Thomas W. Ebbesen

ISIS, Université Louis Pasteur, 8 allée Gaspard Monge, 67000 Strasbourg, France

The transmission of light through a subwavelength aperture, although conceptually very simple, is extremely difficult to describe theoretically. The various approaches that have been used all rely on a certain number of approximations to simplify the problem. The theory of Hans Bethe from 1944 is considered the key reference on this subject and it assumes that the aperture is in an infinitely thin and perfectly conducting metal film. In the real world, the aperture is made in a film of finite thickness and conductivity. The experimental studies being scarce, we have undertaken a detailed study of such single apertures in metal films that reveal that localized surface plasmons on the aperture ridge considerably modifies their transmission properties with respect to the theoretical predictions. As in the case of enhanced transmission through aperture surrounded by periodic corrugations, the surface plasmons modes concentrate the field at the aperture, thereby compensating for the inherently weak tunneling process through the aperture. The relation between the single aperture properties and surface plasmon enhanced transmission through hole arrays will be discussed.

These findings have broad fundamental and practical implications and show that, with modern fabrication techniques, surface plasmons can be engineered and controlled to yield unique optical properties which could find application in high density data storage, photonic integration, near field probes, etc..

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