Abstract: An optical element structure allowing an increased power density of aperture-transmitted light while suppressing increase in temperature is disclosed. A conductive film has a sub-wavelength aperture formed therein and a periodic surface topography formed thereon. A lens focuses light onto the periodic surface topography with a predetermined diameter. The predetermined diameter of incident light on the conductive film and a period of the periodic surface topography are determined so that a power ratio of aperture-transmitted light to the light beam is greater than that of aperture-transmitted light which would be obtained if no periodic surface topography is provided in the conductive film.

Abstract: A read/write head for an optical storage medium is provided. The read/write head comprises a waveguide having an end face and a plasmon-enhanced device provided on the end face of the waveguide. The plasmon-enhanced device comprises a metal film having a first surface and a second surface, the first surface being fixed to the waveguide end face, the metal film having an aperture provided therethrough. The metal film has a periodic surface topography provided on at least one of the first and second surfaces of the metal film. Light incident on one of the surfaces of the metal film interacts with a surface plasmon mode on at least one of the surfaces of the metal film thereby enhancing transmission of light through the aperture in the metal film which is directed onto and/or collected from the optical storage medium. A read/write head with an integral light source is also provided.

Abstract: An optical element structure allowing an increased power density of aperture-transmitted light while suppressing increase in temperature is disclosed. A conductive film has a sub-wavelength aperture formed therein and a periodic surface topography formed thereon. A lens focuses light onto the periodic surface topography with a predetermined diameter. The predetermined diameter of incident light on the conductive film and a period of the periodic surface topography are determined so that a power ratio of aperture-transmitted light to the light beam is greater than that of aperture-transmitted light which would be obtained if no periodic surface topography is provided in the conductive film.

Abstract: A symmetric van der Pauw disk of homogeneous nonmagnetic semiconductor material, such as indium antimonide, with an embedded concentric conducting material inhomogeneity, such as gold, exhits room temperature geometric extraordinary magnetoresistance (EMR) as high as 100%, 9,100% and 750,000% at magnetic fields of 0.05, 0.25 and 4.0 Tesla, respectively. Moreover, for inhomogeneities of sufficiently large cross section relative to that of the surrounding semiconductor material, the resistance of the disk is field-independent up to an onset field above which the resistance increases rapidly. These results can be understood in terms of the field-dependent deflection of current around the inhomogeneity.

Abstract: An apparatus for enhanced light transmission is provided. The apparatus comprises a metal film having a first surface and a second surface, at least one aperture being provided in the metal film and extending from the first surface to the second surface. The at least one aperture comprises an entrance portion disposed on the first surface of the metal film and an exit portion disposed in the second surface of the metal film, each portion having a cross-sectional area in the plane of the corresponding metal film surface, wherein the cross-sectional area of the entrance portion is not equal to the cross-sectional area of the exit portion. A periodic surface topography is provided on at least one of the first and second surfaces of the metal film, the periodic surface topography comprising a plurality of surface features, wherein the geometry of each aperture entrance portion substantially matches the geometry of the surface features.

Abstract: An apparatus for enhanced light transmission is provided. The apparatus comprises a metal film having a first surface and a second surface, at least one aperture being provided in the metal film and extending from the first surface to the second surface. The at least one aperture comprises an entrance portion disposed on the first surface of the metal film and an exit portion disposed in the second surface of the metal film, each portion having a cross-sectional area in the plane of the corresponding metal film surface, wherein the cross-sectional area of the entrance portion is not equal to the cross-sectional area of the exit portion. A periodic surface topography is provided on at least one of the first and second surfaces of the metal film, the periodic surface topography comprising a plurality of surface features, wherein the geometry of each aperture entrance portion substantially matches the geometry of the surface features.

Abstract: A surface-plasmon enhanced photovoltaic device including: a first metallic electrode having an array of apertures, an illuminated surface and an unilluminated surface, at least one of the surfaces having an enhancement characteristic resulting in a resonant interaction of incident light with surface plasmons; a second electrode spaced from the first metallic electrode; and a plurality of spheres corresponding to the array of apertures and disposed between the first metallic and second electrodes, each sphere having a first portion of either p or n-doped material and a second portion having the other of the p or n-doped material such that a p-n junction is formed at a junction between the first and second portions.

Abstract: An apparatus for enhanced light transmission through a perforated metal film is provided. The apparatus comprises a metal film having a first surface and a second surface, at least one aperture provided in the metal film and extending from the first surface to the second surface, and first and second dielectric layers. The first dielectric layer is provided substantially adjacent to the first metal film surface, and the second dielectric layer is provided substantially adjacent to the second metal film surface. The respective refractive indices of the first and second dielectric layers are substantially equal. Light incident on one of the surfaces of the metal film interacts with a surface plasmon mode on at least one of the surfaces of the metal film thereby enhancing transmission of light through the at least one aperture in the metal film.

Abstract: An apparatus for enhanced light transmission is provided. The apparatus comprises a metal film having a first surface and a second surface, at least one aperture provided in the metal film and extending from the first surface to the second surface, and a periodic surface topography provided on at least one of the first and second surface of the metal film. Light incident on one of the surfaces of the metal film interacts with a surface plasmon mode on at least one of the surfaces of the metal film thereby enhancing transmission of light through the at least one aperture in the metal film. The apparatus may have a single aperture or a plurality of periodically arranged apertures. Wavelength-selective optical filters, spatial optical filters, light collectors, near-field scanning optical microscope probes and photolithographic masks are also provided.

Abstract: Thin, horizontal-plane Hall sensors for read-head in magnetic recordings and methods for fabricating the sensor provide a novel sensor exhibiting high sensitivity and high spatial resolution.

Abstract: Thin, horizontal-plane Hall sensors for read-head in magnetic recordings and methods for fabricating the sensor provide a novel sensor exhibiting high sensitivity and high spatial resolution.

Abstract: A metallic film has apertures located therein in an array arranged in a pattern so that when light is incident on the apertures, surface plasmons on the metallic film are perturbed resulting in an enhanced transmission of the light emitted from individual apertures in the array. The aperture array is used: to filter light of predetermined wavelength traversing the apertures, to collect light over a distance after traversing the apertures, to improve operation of near-field scanning optical microscopes, and to enhance light transmission through masks useable in photolithography.

Abstract: A self-biasing, non-magnetic giant magnetoresistive sensor having a Corbino-disk geometry constructed from a thin film of e.g., doped, Mercury Cadmium Telluride (MCT) Hg.sub.1-x Cd.sub.x Te exhibiting anomalously large Giant Magnetresistance (GMR) and zero field offset. In one embodiment, the sensor has a silicon substrate, a layer of doped, inhomogeneous MCT, and electrodes attached to the inhomogeneous layer. Alternatively, a buffer layer of, e.g., CdTe may overlay the substrate. In another embodiment, the sensor has a silicon substrate, a layer of doped, homogeneous MCT, and electrodes attached to the doped homogeneous MCT. Alternatively, a buffer layer of, e.g., CdTe may overlay the substrate as well. With constructed in as either of these embodiments, highly doped Corbino devices may show a significant zero-field offset in the GMR which results in a built-in bias field as high as 1500 G at T=300 K.

Abstract: Generally speaking, in accordance with the invention, an optical transmission modulation apparatus is provided for modulating light transmitted through the apparatus. The apparatus comprises a metal film having a periodic array of subwavelength-diameter holes provided therein, and a supporting layer. At least a portion of the supporting layer has a selectively variable refractive index, the selectively variable refractive index portion being substantially adjacent to the metal film such that the metal film and the supporting layer form a perforated metal film unit. Selective variation of the refractive index of the selectively variable refractive index portion modulates the intensity of the light transmitted through the perforated metal film unit without substantially changing the direction of the light. Flat panel displays, spatial light modulators and tunable optical filters based on the optical transmission control apparatus are also provided.

Abstract: A subwavelength-resolution optical imaging device is provided for conveying light having a wavelength .lambda. that is emitted, reflected or transmitted by a sample. The device comprises a coherent fiber bundle, which itself comprises a plurality of optical fibers disposed substantially coaxially along their lengths. Each optical fiber also comprises a core having an index of refraction n.sub.1 and a cladding having an index of refraction n.sub.2 thereby providing a value .DELTA., where: ##EQU1## Light is effectively confined within the core of each fiber without need for a separate coating applied to the fibers by selecting the values of n.sub.1 and n.sub.2 for each optical fiber so as to provide a value for .DELTA.

Abstract: A metallic film has apertures located therein in an array arranged in a pattern so that when light is incident on the apertures, surface plasmons on the metallic film are perturbed resulting in an enhanced transmission of the light emitted from individual apertures in the array. The aperture array is used: to filter light of predetermined wavelength traversing the apertures, to collect light over a distance after traversing the apertures, to improve operation of near-field scanning optical microscopes, and to enhance light transmission through masks useable in photolithography.

Abstract: The low-field magnetoresistance of a high carrier mobility semiconductor with inhomogeneities which are more conducting than the surrounding semiconductor material matrix is significantly enhanced compared to the magnetoresistance of the homogeneous material. The enhancement results from a magnetic field induced geometric effect in which current is expelled from the conducting inhomogeneity. The enhanced giant magnetoresistance is demonstrated at low field in (near) zero-band-gap material, such as Hg.sub.1-x Cd.sub.x Te(x.about.0.1). The effect is applied to the fabrication of magnetic read head sensors such as Corbino disc, bar magnetoresistance sensors and thin film sensors.

Abstract: A compound semiconductor that is suitably doped to exhibit the DX effect is irradiated with an optical beam of spatially varying intensity whereby localized regions of persistently higher conductivity and lower refractive index are created in the semiconductor where sufficient intensity of the beam was incident. The persistently higher conductive region can be used to bridge selected gaps in conductive paths on a support member use in memory device and the regions of lower refractive index can be used to providing guiding in a wave guide, to form high resolution gratings, or to form holograms.

Abstract: A heterojunction is formed between a pair of layers of different semiconductive materials whose work function difference produces a large band offset at the heterojunction. Donor or acceptor atoms are included in one regions that when photoexcited produce free charge carriers but leave behind charged centers that keep the photoexcited carriers localized. The large barrier at the heterojunction limits recombination of the free charge carriers and the charged centers and persistent photoconductivity results. This effect is used to form light operated switches. An illustrative example uses a layer of high purity gallium arsenide forming a heterojunction with a gallium-doped layer of zinc selenide.

Abstract: A self-biasing, non-magnetic giant magnetoresistive sensor constructed from a thin film of inhomogeneous magnetoresistive material showing Giant Magnetresistance (GMR) at T=300.degree. K., e.g., Mercury Cadmium Telluride. In one embodiment, the sensor has a silicon substrate, a layer of inhomogeneous magnetoresistive material, e.g., Hg.sub.l-x Cd.sub.x Te, and electrodes attached to the non-homogeneous magnetoresistive layer. Alternatively, a buffer layer of, e.g., CdTe may overlay the substrate. In another embodiment, the sensor is an active element of a read/write head, particularly well suited for reading information signals stored in a magnetic medium.