Abstract: This invention relates to optoelectronic devices of improved efficiency. In particular it relates to light emitting diodes, photodiodes and photovoltaics. By careful design of periodic microstructures, e.g. gratings, associated with such devices more efficient light generation or detection is achieved.

Abstract: This invention relates to optoelectronic devices of improved efficiency. In particular it relates to light emitting diodes, photodiodes and photovoltaics. By careful design of periodic microstructures, e.g. gratings, associated with such devices more efficient light generation or detection is achieved.

Abstract: A multilayer surface comprising at least two layers, said layers having different refractive indexes such that selective wavelengths/colours are transmitted and or reflected. The layers are preferably laid onto a transparent substrate. The surface can be used as an anti-counterfeit device. A method of determining whether an article is counterfeit comprising: providing such a surface; determining its transmission/absorption characteristics of particular colour(s); matching these up with the expected characteristics to determine whether the surface is counterfeit. This may comprise observing the reflected or transmitted colour at two different angles of incidence or detecting changes in the polarisation state of transmitted light.

Abstract: A grating comprising a plurality of substantially parallel members having a conducting surface of depth L, separated by a dielectric layer gap, and having of pitch &lgr;g and where L>16&lgr;g. The members are preferably metallic or comprise metallic foil covered plastic. The gap may be filled wholly or partially with dielectric material including liquid crystal whose refractive index can be controlled by suitable application of voltage across the gap.

Abstract: A radiation absorber comprising a substrate having free charges capable of being driven to form resonance charge density oscillators and a dielectric layer coated onto said surface wherein the dielectric layer has a textured/patterned surface. The substrate is preferably metallic and the dielectric layer is waveform.

Abstract: A surface capable of supporting surface charge oscillations and exhibiting a profiled grating, said profile comprising at least two superposed periodic profiles. The surface has applications as radar absorber and authentication devices. Also disclosed is a method of detecting the authenticity of an object comprising providing a surface as described above claim adjacent to or on the object, illuminating said surface with radiation from at least one angle and determining the reflectivity characteristics and comparing this with reflectivity characteristics of a reference surface.

Abstract: A grating comprising a plurality of substantially parallel members having a conducting surface of depth L, separated by a dielectric layer gap, and having of pitch &lgr;g and where L>16&lgr;g. The members are preferably metallic or comprise metallic foil covered plastic. The gap may be filled wholly or partially with dielectric material including liquid crystal whose refractive index can be controlled by suitable application of voltage across the gap.

Abstract: A signature recognition system for identifying an article with a distinctive diffraction element (or elements) and verifying the presence of that element or elements comprising: an article with one or more diffraction gratings impressed thereon, the grating(s) exhibiting periodic wave surface profiles having a depth-to-pitch ratio &dgr; of between 0.1 and 0.5, a source of polarized electromagnetic radiation of wavelength &lgr; such that the pitch G of the periodic wave surface profile of the grating(s) is comparable to an integer multiple n of that wavelength, a device for directing the source of polarized electromagnetic radiation to the surface of the grating(s) at a plane of incidence substantially normal to the plane of the surface of the diffraction grating and at an angle of approximately 45° azimuth to the alignment of the grooves on the surface, and a device for detecting radiation reflected from the grating(s) surface which is oppositely polarized to the incident radiation.

Abstract: An optical sensing device that incorporates either a surface plasmon-polariton or guided mode apparatus for converting radiation between s and p modes together with a sensor for detecting a maximum in conversion between the s and p modes.

Abstract: Optical measuring apparatus including an acousto-optical device (3) which molulates either the angle or the wavelength of a light beam (1) at a frequency determined by a signal generator (15). A detector (13) detects the modulated beam after interrogation of a sample under test; and a lock-in amplifier (14) is connected to the signal generator (15) and to the detector (13) to determine the differential of an optical property of the sample under test.

Abstract: A method for fabricating a microelectronic device of the metal/insulator/metal' type wherein the insulator is an organic material, and a device fabricated thereby. A first electrically conductive lead is conductively adhered to a first portion of a conductive substrate. A monomolecular layer of highly pure p-dodecyloxyphenylcarbamate of 2-(2'-hydroxyethoxy)-5-bromo-7,7,8,8-tetracyanoquinodimethan is deposited on a surface of a second portion of the conductive substrate not including the first portion to form an organic film. Molecules of the monomolecular layer are generally disposed normal to the substrate surface with their dodecyl terminal moieties adjacent the surface. An essentially oxide-free contiguous layer of magnesium is deposited on the organic film. The deposition if performed at a temperature below about 15.degree. C. A layer of silver is deposited on the magnesium layer to substantially cover and conductively adhere to the magnesium layer.