Nano-optics of surface plasmon polaritons

Collective electronic excitations at metal surfaces are well known to play a key role in a wide spectrum of science, ranging from physics and materials science to biology. Here we focus on a theoretical description of the many-body dynamical electronic response of solids, which underlines the existence of various collective electronic excitations at metal surfaces, such as the conventional surface plasmon, multipole plasmons and the recently predicted acoustic surface plasmon. We also review existing calculations, experimental measurements and applications.

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Theory of surface plasmons and surface-plasmon polaritons

Wave propagation and group velocity

Have you ever felt that the very title, Progress in Optics, conjured an image in your mind? Don’t you see a row of handsomely printed books, bearing the editorial stamp of one of the most brilliant members of the optics community, and chronicling the field of optics since the invention of the laser? If so, you are certain to move the bookend to make room for Volume 16, the latest of this series. It contains seven chapters on widely diverging topics, written by well-known authorities in their fields. These are: 1) Laser Selective Photophysics and Photochemistry by V. S. Letokhov, 2) Recent Advances in Phase Profiles (sic) Generation by J. J. Clair and C. I. Abitbol, 3 ) Computer-Generated Holograms: Techniques and Applications by W.-H. Lee, 4) Speckle Interferometry by A. E. Ennos, 5 ) Deformation  Invariant, Space-Variant Optical  Pattern Recognition by D. Casasent and D. Psaltis, 6) Light Emission from High-Current Surface-Spark Discharges by R. E. Beverly, and 7) Semiclassical Radiation  Theory within a  QuantumMechanical Framework by I. R. Senitzkt. The  breadth of topic  matter  spanned  by  these  chapters makes it impossible, for this reviewer at least, to pass judgement on the comprehensiveness, relevance, and completeness of every chapter. With an editorial board as prominent as that of Progress in Optics, however, it seems hardly likely that such comments should be necessary. It should certainly be possible to take the authority of each author as credible. The only remaining judgment to be  made on these chapters is their readability. In short, what are they like to read? The first sentence of the first chapter greets the eye with an obvious typographical error: “The creation of coherent laser light source, that have tunable radiation, opened the . . . .” Two pages later we find: “When two types of atoms or molecules of different isotopic composition ( A and B ) have even one spectral line that does not overlap with others, it is pos-

Progress in optics

Surface infrared spectroscopy

We calculate the dielectric response of free-standing and supported two-dimensional layers of polarizable entities, such as metallic particles or adsorbed molecules. We take into account dipole-dipole and the image interaction and investigate the effects of disorder within a two-dimensional renormalized polarizability theory. The behavior of the resonances arising from both the single particle's and the substrate's surface plasmon is studied.

Optical properties of two-dimensional disordered systems on a substrate

We calculate the nonlinear dipole and quadrupole moments induced at the second-harmonic (SH) frequency $2\ensuremath{\omega}$ in a small dielectric sphere by an inhomogeneous monochromatic electric field of frequency $\ensuremath{\omega}.$ We neglect finite-size effects and assume that the selvedge region of the sphere is thin enough so that the surface may be considered locally flat. The second-order dipole displays resonances corresponding to the excitation of dipolar and quadrupolar plasmons at $\ensuremath{\omega}$ and a dipolar plasmon at $2\ensuremath{\omega},$ besides the resonances in the nonlinear surface response parameters a, b, and f. The second-order quadrupole, on the other hand, has resonances corresponding to those of a, b, and f, and to the excitation of dipolar surface plasmons at $\ensuremath{\omega}$ only. Depending on the relation between the size of the sphere and the spatial scale of variation of the field, the SH radiation may be dominated by either dipolar or quadrupolar scattering, with a crossover region. As an application, we calculate the SH scattering of a Si sphere lying at various distances above a dielectric substrate.

Second-harmonic generation from spherical particles

We obtain exact expressions for the Casimir forces between arbitrary materials using the concept of surface impedance. We verify their consistency with the well-known expressions for perfect conductors and with Lifshitz formula for semi-infinite local homogeneous media. As an application we present a full and rigorous calculation of the Casimir force between two metallic half spaces described by a hydrodynamic nonlocal dielectric response.

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Exact surface impedance formulation of the Casimir force: Application to spatially dispersive metals

We develop a simple theory for the macroscopic dielectric function of a system of identical spheres embedded in a homogeneous matrix within the dipolar long-wavelength approximation. We obtained a relationship similar to the Clausius-Mossotti relation, but with a renormalized polarizability for the spheres instead of the bare polarizability. This renormalized polarizability obeys a second-order algebraic equation and it is given in terms of the bare polarizability, the volume fraction, and a functional of the two-particle correlation function of the spheres. We calculate the optical properties of metallic spheres within an insulating matrix and we compare our results with previous theories and with experiment.

Renormalized polarizability in the Maxwell Garnett theory

We obtain closed-form expressions for the macroscopic dielectric response of systems with spatial fluctuations, taking into account the local-field effect. The macroscopic response is written, without reference to any specific representation, in terms of the microscopic dielectric operator and the projection operators that extract the average and the fluctuation components of the microscopic fields. The results are very general since few assumptions are made about the nature of the system and of its microscopic response, and very relaxed conditions are imposed on the average and fluctuation projectors. We put special emphasis on systems for which the length scale of the fluctuations is much smaller than the wavelength of light.

W. Luis Mochán

Papers

Optical properties of two-dimensional disordered systems on a substrate

Second-harmonic generation from spherical particles

Exact surface impedance formulation of the Casimir force: Application to spatially dispersive metals

Renormalized polarizability in the Maxwell Garnett theory

Electromagnetic response of systems with spatial fluctuations. I. General formalism.