Abstract: In accordance with the present invention, optical fiber communications systems are provided with one or more long period spectral shaping devices to shift light of unwanted wavelength from guided modes into non-guided modes. Such devices can be used for removing unused laser pump energy, for removing amplified spontaneous emission, and for flattening the spectral response of an erbium amplifier. Such devices can also provide optical fiber sensing systems with inexpensive shift detectors.

Abstract: Disclosed is a method for forming a superconductive oxide layer on a substrate. The method comprises applying a precursor solution to a major surface of the substrate such that a metal-containing layer is formed on the surface, and heat treating the substrate/layer combination such that at least a substantial portion of the layer material is transformed into superconductive oxide. Exemplarily, the precursor solution is formed by dissolving Ba--, Y--, and Cu-containing compounds in acetic acid and water, spinning the solution on a MgO substrate, driving of unwanted constituents of the resulting layer at 400.degree. C., heating the combination to about 830.degree. C. in O.sub.2 such that the (perovskite) phase that is associated with superconductivity in YBa.sub.2 Cu.sub.3 O.sub.7 is formed, and oxygenating the layer at about 400.degree. C. in O.sub.2.

Abstract: In accordance with the invention, a mode-field transforming waveguide region comprise an elongated glass core surrounded by glass cladding wherein the normalized index differential between the cladding and the core (termed .DELTA.) varies along the length. Preferably the waveguide comprises an optical fiber having a hydrogen-loaded germanosilicate core. The variation of .DELTA. as a function of longitudinal distance can be effected by exposing the fiber to ultraviolet light and varying the dosage of exposure as a function of longitudinal distance.

Abstract: Applicant has discovered that aliovalently doped gallium-indium-oxide (GaInO.sub.3) can achieve electrical conductivity comparable to wide band-gap semiconductors presently in use while exhibiting enhanced transparency and improved index matching. The material can be doped to resistivity of less than 10 milliohm-cm by small quantities of aliovalent dopants, such as tetravalent atoms. It has a refractive index of about 1.6 and can be deposited on glass substrates in polycrystalline films.

Abstract: This invention is predicated upon applicants' discovery that conventional techniques for minimizing metal loss from sintered ceramic materials are not adequate in the fabrication of small ceramic components such as multilayer monolithic magnetic devices wherein a magnetic core is substantially surrounded by an insulating housing. Applicants have determined that this metal loss problem can be solved by providing the component with a housing layer having an appropriate concentration of metal. Specifically, if the insulating housing material around the magnetic core has, during the high temperature firing, the same partial pressure of metal as the magnetic core material, there is no net loss of metal from the core. In a preferred embodiment, loss of zinc from a MnZn ferrite core is compensated by providing a housing of NiZn ferrite or zinc aluminate with appropriate Zn concentrations. Similar considerations apply to other ceramic components.

Abstract: The present applicants have discovered that one can make a surface emitting laser with enhanced optical confinement and improved heat sinking characteristics by etching away portions of the growth layers peripheral to the intended laser cavity and regrowing peripheral regions of material having a lower index of refraction than the active region. Using low damage etching and either in situ regrowth or hydrogen plasma cleaning followed by regrowth, a surface emitting laser having enhanced optical isolation and heat sinking characteristics can be made.

Abstract: Applicants have discovered that a particularly efficient illuminating device for a transparent display comprises a microtextured reflecting surface formed on a major surface of a transparent substrate and a light source for directing light into the transparent substrate approximately parallel to the major surface. Preferably the substrate has two major surfaces separated by a thickness in the range 0.5 to 1.0 mm so that the substrate acts as a light guide. A substantial portion of the light passing into the substrate undergoes total internal reflection until it hits a microelement and is reflected out of the substrate. The result is an efficient illuminating device particularly useful for lighting transparent displays.

Abstract: Applicant has demonstrated that by appropriately shaping the laser gain region one can control the polarization direction of semiconductor vertical cavity lasers and enhance their transverse mode selectivity. Specifically, configuring the transverse cross section to regions have a length-to-width ratio in excess of 1.2 favors emission with polarization in the long dimension at the fundamental mode. A cruciform structure favors emission with switchable orthogonal polarization. The transverse shape can be configured by dry etching a particular cavity shape in index guided lasers or by forming a shaped ion implantation region around gain guided lasers.

Abstract: Applicants have discovered that by heating cured polymer-coated fiber at temperatures of 100.degree. C. or more, they can enhance the fiber pullout strength by 25% or more. This postcure heating can advantageously be done off-line by placing loosely wound fiber in a heated oven. Alternatively the postcure heating can be done on-line by reel-to-reel passage of the fiber through a heated furnace. Preferred temperatures are in the range 100.degree. C.-300.degree. C.

Abstract: In accordance with the invention the birefringence induced by compressive strain in silica waveguides on silicon substrates is compensated with a high index patch--such as silicon nitride--placed adjacent the core. The patch is disposed sufficiently close to the core to optically couple with the transmitted optical mode. The patch is preferably wider than the core to intersect the exponential tail of the transmitted optical mode. Such a high index patch preferentially couples TE polarization modes. By choosing an appropriate length for the patch, both strain and bend birefringence can be compensated.

Abstract: In accordance with the invention, an image is formed by applying a local magnetic field to selected regions of a magnetic composite medium comprising columns of magnetic particles distributed in a matrix medium. The particles are "hard" or "semi-hard" magnetic materials in order to retain the latent image as residual magnetism, and the image is developed by exposure to magnetic fluid or powders. The image can be erased by exposure to an AC demagnetizing field or a DC sweep magnet. Preferred apparatus for making such images comprises a sheet of such composite material having a pair of major surfaces with columns of magnetic particles oriented between the surfaces. A local magnetic field, such as a magnetic pen, can be used to write a latent magnetic image on one of the major surfaces. The magnetic columns present the latent image for development at either major surface.

Abstract: In accordance with the present invention, a silicon device fabricated on a (100) silicon substrate is provided with a (111) slant surface and an electrical contact comprising epitaxial low Schottky barrier silicide is formed on the (111) surface. For example, low resistance rare earth silicide contacts on V-groove surfaces are provided for the source and drain contacts of a field effect transistor. The resulting high quality contact permits downward scaling of the source and drain junction depths. As another example, rare earth silicide Schottky contacts are epitaxially grown on V-groove surfaces to provide low voltage rectifiers having both low power dissipation under forward bias and low reverse-bias leakage current.

Abstract: The present applicant has discovered that one can make a surface emitting laser with enhanced operating characteristics by etching away the outer reflector stack peripheral to the intended active area and protecting the reflector stack mesa remaining over the active area by in situ metalization in high vacuum. The active area can be isolated, as by ion implantation, providing an electrical path through the active region free of the outer reflector stack. The result is a surface emitting laser having reduced series resistance. The device lases at lower voltage and provides an enhanced intensity of optical output as compared with conventional planar devices.

Abstract: In accordance with the present invention, a tactile sensor capable of detecting shear force comprises an anisotropically conductive material disposed between a conductive cursor and an array of contacts. In one preferred embodiment, the anisotropic material is affixed to the contact array, and the cursor is affixed to an elastomeric skin overlying the material. Movement of the cursor is detected by interconnection of the contacts underlying the cursor. In a second embodiment, the anisotropic material is affixed to the cursor but is free to move over the contact array in response to shear force. Movement of the cursor is detected by interconnection of the underlying contacts. Such arrangements can also detect pressure and temperature.

Abstract: The present invention is a method for making field effect devices, such as a field effect transistors, having ultrashort gate lengths so low as five hundred angstroms or less. In accordance with the invention the gate structure is grown vertically on a substrate by thin film deposition so that the length dimension of the gate is perpendicular to a major surface of the substrate. An edge of the gate-containing substrate is exposed, and the structure comprising the source, drain and channel is grown on the edge. Using this approach, field effect devices with precisely controlled gate lengths of less than 100 angstroms are achievable. Moreover the active regions of the device can be immersed within semiconductor material so that surface properties do not deteriorate device performance.

Abstract: In accordance with the invention, a quantum well device provides localized states for electrons having an energy E greater than the barrier height of the constituent quantum wells. The device comprises a confinement quantum well of width L.sub.w equal to an integer number n of deBroglie half wavelengths ##EQU1## and a plurality of adjacent quarter wavelength barriers and wells, each having a thickness equal to an odd number m of deBroglie quarter wavelengths. Constructive interference between the waves partially reflected by the interfaces between adjacent .lambda./4 barriers and .lambda./4 wells leads to the formation of a localized electron state at an energy E in the region of the confinement well. The device can be used in detectors and modulators employing transitions between a bound state within the well and the localized state above the well.

Abstract: The invention is predicated upon the discovery by applicants that exposure of a Ge surface to arsenic produces a drastic change in the step structure of the Ge surface. Subsequent exposure to Ga and growth of GaAs produces three-dimensional growth and a high threading dislocation density at the GaAs/Ge interface. However exposure of the Ge surface to Ga does not substantially change the Ge step structure, and subsequent growth of GaAs is two-dimensional with little increase in threading dislocation density. Thus a high quality semiconductor heterostructure of gallium arsenide on germanium can be made by exposing a germanium surface in an environment substantially free of arsenic, depositing a layer of gallium on the surface and then growing a layer of gallium arsenide. The improved method can be employed to make a variety of optoelectronic devices such as light-emitting diodes.

Abstract: Applicants have discovered a method of reproducibly fabricating SEED devices having an enhanced contrast ratio by adjusting the thickness of a cap layer in relation to the reflector stacks to form a Fabry-Perot cavity. Specifically, after growth of the reflector stack and the quantum wells, the optical thickness of the region above reflector stacks is measured without breaking vacuum, and based on such measurement a cap layer is grown of sufficient thickness to form a Fabry-Perot cavity for light of desired wavelength. The result is a device with enhanced contrast between the "on" and "off" states sufficiently so that the state can be directly read without differential processing.

Abstract: FETs and quantum well diodes are combined on the same semi-insulating substrate, while providing the FETs with protection from spurious voltages. A deeply buried P region in the semi-insulating substrate is partitioned by a high resistivity proton implanted region, to provide both the P region of the quantum well diode and an isolating buried P layer for the FETs.

Abstract: The formation of latent images in photoresist can be monitored during exposure without spurious images by directing a pulsed beam of monochromatic light onto a region of the layer being exposed and selectively detecting the diffracted light. Peak formation in the normalized diffracted intensity versus time curve indicates optimal exposure of the resist.