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Journal ArticleDOI

Optical properties of thin films

David E. Aspnes1
19 Mar 1982-Thin Solid Films (Elsevier)-Vol. 89, Iss: 3, pp 249-262
TL;DR: In this article, the connection between microstructure and absolute limits to the allowed values of the dielectric response of two-phase composites is reviewed and a solution of the Clausius-Mossotti problem is developed from basic principles.
About: This article is published in Thin Solid Films.The article was published on 1982-03-19. It has received 1433 citations till now. The article focuses on the topics: Surface roughness & Isotropy.
Citations
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Journal ArticleDOI
09 Jun 1995-Science
TL;DR: A highly ordered metal nanohole array (platinum and gold) was fabricated by a two-step replication of the honeycomb structure of anodic porous alumina that showed a notable color change compared with bulk gold.
Abstract: A highly ordered metal nanohole array (platinum and gold) was fabricated by a two-step replication of the honeycomb structure of anodic porous alumina. Preparation of the negative porous structure of porous alumina followed by the formation of the positive structure with metal resulted in a honeycomb metallic structure. The metal hole array of the film has a uniform, closely packed honeycomb structure approximately 70 nanometers in diameter and from 1 to 3 micrometers thick. Because of its textured surface, the metal hole array of gold showed a notable color change compared with bulk gold.

4,892 citations

Journal ArticleDOI
TL;DR: In this paper, the surface plasmon absorption of noble metal nanoparticles was studied and the effects of size, shape, and composition on the plasman absorption maximum and its bandwidth were discussed.
Abstract: The field of nanoparticle research has drawn much attention in the past decade as a result of the search for new materials. Size confinement results in new electronic and optical properties, possibly suitable for many electronic and optoelectronic applications. A characteristic feature of noble metal nanoparticles is the strong color of their colloidal solutions, which is caused by the surface plasmon absorption. This article describes our studies of the properties of the surface plasmon absorption in metal nanoparticles that range in size between 10 and 100 nm. The effects of size, shape, and composition on the plasmon absorption maximum and its bandwidth are discussed. Furthermore, the optical response of the surface plasmon absorption due to excitation with femtosecond laser pulses allowed us to follow the electron dynamics (electron−electron and electron−phonon scattering) in these metal nanoparticles. It is found that the electron−phonon relaxation processes in nanoparticles, which are smaller than t...

3,635 citations

Journal ArticleDOI
TL;DR: This work presents the design of a non-magnetic cloak operating at optical frequencies, and the principle and structure of the proposed cylindrical cloak are analysed and the general recipe for the implementation of such a device is provided.
Abstract: Artificially structured metamaterials have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities, including the cloak of invisibility based on coordinate transformation1,2,3. Unlike other cloaking approaches4,5,6, which are typically limited to subwavelength objects, the transformation method allows the design of cloaking devices that render a macroscopic object invisible. In addition, the design is not sensitive to the object that is being cloaked. The first experimental demonstration of such a cloak at microwave frequencies was recently reported7. We note, however, that that design7 cannot be implemented for an optical cloak, which is certainly of particular interest because optical frequencies are where the word ‘invisibility’ is conventionally defined. Here we present the design of a non-magnetic cloak operating at optical frequencies. The principle and structure of the proposed cylindrical cloak are analysed, and the general recipe for the implementation of such a device is provided.

1,953 citations

Journal ArticleDOI
TL;DR: In this article, a collector consisting of two pieces of electrically conductive substrates separated by a gap whose width could be varied from hundreds of micrometers to several centimeters.
Abstract: Electrospinning has been applied to prepare uniaxially aligned nanofibers made of organic polymers, ceramics, and polymer/ceramic composites The key to the success of this method was the use of a collector consisting of two pieces of electrically conductive substrates separated by a gap whose width could be varied from hundreds of micrometers to several centimeters As driven by electrostatic interactions, the charged nanofibers were stretched to span across the gap and thus to become uniaxially aligned arrays over large areas Because the nanofibers were suspended over the gap, they could be conveniently transferred onto the surfaces of other substrates for subsequent treatments and various applications Materials that have been successfully incorporated into this procedure include conventional organic polymers, graphite carbon, and metal oxides By controlling the parameters for electrospinning, we have also fabricated a number of simple device structures, for example, an individual nanofiber spanning

1,460 citations

Journal ArticleDOI
TL;DR: In this article, a methodology to correlate the absolute surface concentration of protein to the surface plasmon resonance (SPR) response is described, and the thickness and the optical constants for each layer on the sensor chip used were determined with different optical techniques.

1,079 citations

References
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Book
01 Jan 1962

24,003 citations

Book
01 Jan 1977
TL;DR: In this article, the polarization of light waves and propagation of polarized light through polarizing optical systems are discussed. But the authors focus on the application of ellipsometry in the field of measurement in ellipsometer systems.
Abstract: Preface. 1. The polarization of light waves. 2. Propagation of polarized light through polarizing optical systems. 3. Theory and analysis of measurements in ellipsometer systems. 4. Reflection and transmission of polarized light by stratified planar structures. 5. Instrumentation and techniques of ellipsometry. 6. Applications of ellipsometry. Appendix. Author index. Subject index.

4,634 citations

Journal ArticleDOI
TL;DR: In this article, the authors established and applied variational theorems for the derivation of bounds for the effective magnetic permeability of macroscopically homogeneous and isotropic multiphase materials.
Abstract: Variational theorems are established and applied to the derivation of bounds for the effective magnetic permeability of macroscopically homogeneous and isotropic multiphase materials. For reasons of mathematical analogy the results are also valid for the dielectric constant, electric conductivity, heat conductivity, and diffusivity of such materials. For the case of two‐phase materials, the bounds derived are the most restrictive ones that can be given in terms of the phase permeabilities and volume fractions. Comparison of present theoretical results with existing experimental data shows good agreement.

2,887 citations

Journal ArticleDOI
TL;DR: In this article, Bruggeman and Maxwell Garnett showed that the dielectric properties of microscopically rough layers of thicknesses 100-500 \AA{}A are accurately modeled in the effective medium approximation.
Abstract: Using measured dielectric function data from 2.1 to 5.5 eV for chemical-vapor-deposition---grown smooth amorphous ($a$-Si) and microscopically rough fine-grained polycrystalline ($p$-Si) films, we show that the dielectric properties of microscopically rough layers of thicknesses 100-500 \AA{}A are accurately modeled in the effective-medium approximation. These microscopically rough layers show essentially no macroscopic light scattering, and thus are inaccessible to measurement by usual scattering techniques. The unambiguous identification of microscopic roughness, as opposed to, e.g., an overlying oxide, is shown to require a spectroscopic capability. Statistical-analysis techniques are introduced to determine model parameters systematically and objectively, and also to establish correlations and confidence limits that show which parameters are defined by the data and which are statistically indeterminate. A best-fit five-parameter model for the sample with the thickest surface region shows that the density profile is characteristic of hemispherical, not pyramidal, irregularities. This indicates that surface roughness arises from a three-dimensional nucleation and growth process in these samples. In a comparison of the three one-parameter effective-medium models, Bruggeman and Maxwell Garnett(2) theories are found to adequately represent the data, while the Lorentz-Lorenz model, previously used exclusively to model roughness in single-wavelength applications, predicts only qualitatively the spectral dependence and gives poor results.

937 citations

Book
01 Jan 1951

694 citations