A new structure for enhanced transmission through a two-dimensional metallic grating.

The spectral response of metallic two-dimensional periodic structures in which circular apertures are engraved has been extensively studied. We show that in such devices transmission can be highly enhanced by partially shutting the central parts of each aperture in order to make a periodic array of subwavelength coaxial structures.

Asymmetrical properties of the optical reflection response of the Fabry-Pérot interferometer.

It may be shown that, even when a Fabry-Pérot interferometer is used with plane waves propagating at normal incidence, the variations of the intensity reflected by it with respect to the phase difference (induced by the distance between the two mirrors) are generally not symmetrical around its extrema. We study this problem and express the necessary and general conditions for obtaining a symmetrical optical response in the reflection mode. We analyze the simple case of a Fabry-Pérot interferometer the first mirror of which is constituted by a thin layer of metal.

Huygens-Fresnel principle in the near field.

The Huygens-Fresnel principle provides a conceptual understanding for wave propagation and diffraction. Recently the principle has been reexamined to suggest that it is also valid in the near field. We reformulate the problem in terms of nonradiative optics, focusing particularly on the obliquity factor inherent in the forward-directed propagation of light. In the near field of matter no explicit obliquity factor exists.

Superresolution of near-field optical microscopy defined from properties of confined electromagnetic waves.

The experimental resolution that is obtained with a near-field microscope by optical tunneling detection is far beyond the Rayleigh criterion. We discuss the principal physical characteristics of this superresolution. Three different examples are presented. They show that the resolution increases as the collector width and collector-to-object distance decrease. It is interesting to note that, in the near-field microscope, as in all local probe microscopes, the resolution cannot be defined from the characteristics of the microscope only. In all tunnel devices the detector cannot be separated from the object. The superresolution that can be obtained results from this fact. This paper also points out the importance ofevanescent waves in near-field optics and makes the connection between resolving power and evanescent fields.

Detection of nonradiative fields in light of the Heisenberg uncertainty principle and the Rayleigh criterion.

The new concept of superresolution microscopy involving nonradiative field detection by optical tunneling is analyzed in light of the Heisenberg principle and the Rayleigh criterion. A connection is demonstrated between the evanescent field components and the system's resolving power. This work is quite general and can be applied to scanning electronic tunneling microscopy.

External and internal reflection near field microscopy: experiments and results.

Two configurations of a scanning near field optical microscope working in reflection are presented. Results exhibiting nanometric resolution are given and discussed.

General principles of scanning tunneling optical microscopy.

A homogeneous propagating wave falling onto submicrometer objects is partially diffracted into evanescent waves. The use of a scattering probe of subwavelength size can convert the evanescent waves into homogeneous ones and make their detection possible. The resulting propagating waves can then provide information about the subwavelength object. Relations with preliminary experiments are discussed.

Numerical study of the displacement of a three-dimensional Gaussian beam transmitted at total internal reflection. Near-field applications.

Longitudinal and transverse shifts of a light beam at total internal reflection was experimentally studied by far-field measurements on the reflected field. We propose to use a scanning tunneling optical microscope (STOM) to study these shifts in transmission, and we present a theoretical model of this proposed experiment to obtain a numerical estimation of these shifts. We study the reflection and the transmission of a three-dimensional polarized incident beam. We verify the validity of our formalism by studying the Goos-Hanchen shift in reflection and by comparing our results with published ones. Then we calculate STOM images of the transmitted field distribution. On the images the well-known Goos-Hanchen shift is easily observed. But we also encounter a smaller shift, perpendicular to the plane of incidence. This transverse shift was also observed in reflection by Imbert and Levy [Nouv. Rev. Opt. 6, 285 (1975)]. We study the variations of the two shifts versus various parameters such as the angle of incidence, the optical index, and the incident polarization. Then we discuss the feasibility of the near-field observation of these shifts.