Abstract: The disclosed means for coupling an optical fiber and an opto-electronic device (e.g., LED, Laser, or photodetector) comprises a first body having two substantially parallel major surfaces, with a recessed portion (a "well") formed in one surface, and a through-aperture extending from the other surface to the well. Conductive means extend from the former surface onto the bottom of the well, and the opto-electronic device is to be mounted in the well such that the device does not protrude above the plane of the associated surface, such that electrical contact is established between the device and the conductive means, and such that the active region of the device is centered upon the through-aperture. The first body is advantageously from a (100) Si wafer by means of standard Si processing techniques, including selective etching. The assembly can be mounted on a substrate, e.g.

Abstract: A transistor is described which the base region comprises a submonolayer of essentially only dopant atoms. One embodiment is a GaAs/AlGaAs heterojunction bipolar transistor in which the base region comprises a submonolayer of Be atoms. The effective base transit time is negligible in these transistors.

Abstract: Disclosed is a technique, termed "mesotaxy", for producing a heteroepitaxial structure comprising a layer of single crystal second material embedded in, and epitaxial with, a single crystal first material matrix. Mesotaxy comprises implantation of at least one chemical species (e.g., Co, Ni, Cr, Y or Mg) into a single crystal body (typically a semiconductor, e.g., Si or Ge) such that a buried layer rich in the implanted species is formed, and heat treating the implanted body such that a buried stoichiometric compound layer (e.g., CoSi.sub.2) is formed. Exemplarily, 3.multidot.10.sup.17 /cm.sup.2 200 keV Co ions are implanted into (100) Si nominally at 350.degree. C., followed by a heat treatment that consists of 1 hour at 600.degree. C. and 30 minutes at 1000.degree. C. The resulting buried CoSi.sub.2 layer is epitaxial with the Si matrix, has high conductivity and is of good crystalline quality. The Si overlayer is of device quality.

Abstract: A glass body having a graded (substantially Gaussian) index profile is produced by a process that comprises providing a doped porous body (e.g., having a uniform dopant distribution), heat treating the porous body in a halogen-containing atmosphere, and consolidating the porous body into the glass body. The heat treatment removes a predetermined portion of the dopant from the porous body, such that the radial dopant profile in the glass body differs from the initial profile in the porous body, and such that the Gaussian index profile results. Exemplarily, the porous body is a uniformly germania-doped, VAD-produced, high-silica rod having radially decreasing density, and the heat treatment comprises an 8-hour densification soak at 1300.degree. C. in 20% Cl, 80% He. In a preferred embodiment, silica overcladding is deposited on a graded index core rod produced according to the invention, and fiber drawn from the resulting composite glass body.

Abstract: Tandem grooves (or other groove-like features) with controlled transition between the narrow and wide portion of the groove can be formed in a (100) Si surface by a method that comprises patterning a first masking layer such that the resulting aperture in the masking layer defines the tandem groove, recovering the narrow part of the aperture with a second masking layer, subjecting the wide portion of the aperture to an initial etch, removing the second masking layer from the narrow part of the aperture, and subjecting the aperture to a further etch such that both the wide and the narrow portions of the tandem V-groove are completed. The inventive method is advantageously used to produce grooves that allow attachment of a coated optical fiber to a Si substrate.

Abstract: A grease composition comprising oil, colloidal particle filler, and, optionally, a bleed inhibitor is disclosed. The grease typically has a critical yield stress below 140 Pa at 20.degree. C., preferably below 70 or 35 Pa. The grease can advantageously be used as a cable filling material, especially for optical fiber cable. In the latter case it can result in cable having substantially no cabling loss. Preferred compositions comprise 77 to 95% b.w. of ASTM type 103, 104 A, or 104B paraffinic or naphthenic oil, or polybutene oil; 2 to 15% b.w. of hydrophobic or hydrophilic fused silica; and optionally, up to 15% b.w. of styrene-rubber or styrene-rubber-styrene block copolymer, or semiliquid rubber.

Abstract: Raman-active optical fiber having very large Raman cross section is disclosed. The fiber comprises glass that has two major components, a glass-forming first component (GeO.sub.2, SiO.sub.2, AsO.sub.1.5, or combinations thereof) and a heavy metal oxide second component (PbO, BiO.sub.1.5, SbO.sub.1.5, TlO.sub.0.5, or combinations thereof), with the first and second major components making up at least 70 mol %, preferably at least 90 mol %, of the glass. The maximum relative Raman cross section .sigma..sub.r of the inventive glass is at least 15, preferably greater than 20, where .sigma..sub.r =.sigma..sub.RA /.theta..sub.SiO.sbsb.2, and where .sigma..sub.RA and .sigma..sub.SiO.sbsb.2 are the maximum 0.degree. K. Raman cross sections of the inventive glass and of pure vitreous SiO.sub.2, respectively.

Abstract: Computing apparatus (e.g., a neural network) advantageously comprises a programmable resistor body comprising typically a multiplicity of resistors R.sub.ij. The resistance of any given R.sub.ij is changeable from a relatively high resistance to a lower resistance by application of an appropriate electrical signal, and can be reset to a higher resistance by application of an appropriate signal of reverse polarity. Exemplarily, a programmable resistor body comprises a thin layer of bismuth oxide or strontium barium niobate.

Abstract: The disclosed method of producing optical fiber comprises providing a silica-based glass rod of diameter D that comprises a core region of effective diameter d surrounded by cladding material (D/d typcially>2) and a silica-based porous jacketing tube, inserting the glass core rod into the porous tube, consolidating the porous material and sintering the jacketing tube onto the core rod such that a substantially pore-free optical fiber preform results. Fiber is then drawn from the preform in the conventional manner. Consolidation and sintering is carried out at a temperature below the softening temperature of the material, typically <1600.degree. C. In a preferred embodiment, the porous tube is produced by a sol/gel process that comprises mixing colloidal silica (surface area 5-100 m.sup.

Abstract: The disclosed simple, economical and rapid sol-gel process for forming a silica-based glass body, termed the "vapogel" process, comprises introduction of a silicon halide-containing gas (e.g., SiCl.sub.4 +O.sub.2) into an aqueous medium. The thus formed sol can gel within minutes, resulting in a monolithic gel from which particles having a narrow size distribution can easily be formed. The thus formed particles can be used to produce a glass body such as an optical fiber. Various techniques for forming the glass body from the gel are disclosed. Among the many advantages of the vapogel method are its ability to produce very homogeneous mixed oxide glasses of composition not obtainable by prior art sol-gel processes, and the advantageous mechanical properties of the gel produced by the method. The latter makes possible, inter alia, formation of particles having a relatively narrow size distribution.

Abstract: An article for the sustained release of an insecticide into the ambient air comprises an elastomeric matrix, with the insecticide dissolved in the matrix. The matrix material has a modulus between about 10.sup.4 Pa and about 10.sup.8 Pa at 23.degree. C., and a glass transition temperature less than 0.degree. C. The matrix comprises polyurethane formed by reacting hydroxyl-terminated polybutadiene or polyisoprene and 4,4' diphenylmethane diisocyanate, and the insecticide is 2,2' dichlorovinyl dimethyl phosphate. The insecticide-containing matrix is contained in a plastic bottle, and typically protected against inadvertent skin contact by means of a dermal barrier. The article also comprises means for activating the article such that, prior to activation, release of insecticide into the ambient air is prevented, whereas such release can take place after activation. Exemplary activation means comprise a metal foil seal of the plastic bottle. The article is effective in controlling insect infestation (e.g.

Abstract: Disclosed is apparatus comprising a source of pump radiation, a multilayer planar waveguide structure that can serve as an efficient harmonic generator, parametric amplifier or parametric oscillator, and means for utilizing the radiation generated in the waveguide structure. The structure consists of a multilayer core region bounded above and below by a (typically optically linear) cladding region. The core region comprises two optically nonlinear layers separated by an optically linear spacer. The layer thickness and refractive indices are selected such that, at a pump frequency f.sub.o, the effective index of the core region is greater than the respective refractive indices of the cladding regions, that the refractive indices of the two nonlinear layers are greater than the refractive index of the spacer, and that a predetermined mode of pump radiation is phasematched with a predetermined mode of a second radiation at a frequency .noteq.f.sub.

Abstract: A novel epitaxial phosphor having high luminosity at about 540 nm has the composition (Y.sub.3-x-y Tb.sub.x RE.sub.y)(Al.sub.5-w Ga.sub.w)O.sub.12, with RE being one (or more) 4f-type rare earth(s) other than Tb, 0.09<x<0.7, and 1.5<w<2.5. In preferred embodiments, RE is Lu, Yb, or Tm, 0.1<x<0.3, and 1.8<w<2.2. In further preferred embodiments, the phosphor composition is adjusted to yield a material having a lattice constant within 0.002 nm of the lattice constant of the substrate, typically Y.sub.3 Al.sub.5 O.sub.12. The phosphor is typically grown by liquid phase epitaxy and has application in a variety of apparatus, including avionic displays and flight simulators.

Abstract: The inventive method for forming monolithic nonlinear Fabry-Perot etalons comprises depositing on an appropriate substrate, e.g., a GaAs wafer, a first multilayer mirror, depositing on the first mirror a spacer typically comprising optically nonlinear material, and depositing a second multilayer mirror onto the spacer. Typically, at least one of the mirrors is an active mirror comprising optically nonlinear material. Deposition can be by a known process, e.g., by MBE or MOCVD. Since, inter alia, the method comprises no critical etching steps it can be used to produce high finesse etalons that have uniform properties over relatively large areas. The inventive method can be adapted to the manufacture of transmissive etalons. It can also be used to produce arrays of optically isolated etalons. Devices comprising nonlinear etalons manufactured by the inventive method can be incorporated, for instance, into optical data processing apparatus, or into optical communications apparatus.

Abstract: Disclosed is a novel switching device. In its currently preferred embodiment the device comprises a conductive path that comprises a superconductive section, with the remainder of the path being non-superconductive, means for applying a voltage across the path such that a current flows, and means for changing the current in the path from a first value to a second value, where one of the two values is below, and the other is above, a critical current associated with the superconductive section of the path. Depending on the choice of applied voltage and path parameters changing the current from the first to the second state results in switching of the current, either oscillating between two levels of current, or to a steady value. Exemplarily, the current is changed by changing the applied voltage or by changing the resistance of the non-superconductive portion of the conductive path. The device can be used as, for instance, a microwave oscillator or a (binary) photodetector.

Abstract: We have discovered that high quality subcritical SIMOX silicon-on-insulator wafers can be produced by a method that comprises a randomizing implant followed by an appropriate heat treatment. In a preferred embodiment, the inventive method comprises, in succession, a subcritical oxygen implant (nominal wafer temperature <350.degree. C.) into a (100) Si wafer, a low temperature (500.degree.-700.degree. C.) anneal, a high temperature (>1200.degree. C.) anneal, a randomizing implant (.about.5.times.10.sup.14 Si/cm.sup.2, nominal wafer temperature <100.degree. C.), and a low temperature anneal (nominal wafer temperature between 500.degree. and 700.degree. C.). The resulting buried SiO.sub.2 layer typically is relatively thin (e.g., 60 nm), stoichiometric, continuous, and essentially free of Si inclusions, and the Si overlayer typically is of device quality and essentially free of twins, with .chi.min.about.3%.

Abstract: Optical radiation can be efficiently removed from, or injected into, single mode optical fiber at an intermediate point along the fiber, by causing quasi-resonant coupling of the guided mode LP.sub.01 to an appropriate tunneling leaky (TL) mode, e.g., LP.sub.11. Such coupling is caused by means of a "grating" in the fiber, with the grating being formed by impressing a periodic (or pseudo-periodic) modulation on the fiber, or by causing a periodic (or pseudo-periodic) variation of the refractive index of the fiber by means of the photoelastic or the photorefractive effect. The nominal grating spacing .LAMBDA.(z) is chosen such that .OMEGA..sub.o =(2.pi./.LAMBDA.)>.beta..sub.01 -2.pi.n.sub.cl /.lambda..sub.o, where .LAMBDA. is the average grating spacing, .beta..sub.01 is the propagation constant of the LP.sub.01 mode, n.sub.cl is the refractive index of the fiber cladding, and .lambda..sub.o is the wavelength of the radiation to be coupled from or into the fiber. Furthermore, .LAMBDA.

Abstract: A single mode optical fiber ribbon cable is disclosed. In preferred embodiments, the cable comprises a filling compound having a critical yield stress less than about 70 Pa at 20.degree. C. and/or fibers having a coating that comrises a low modulus (less than about 1.5.multidot.10.sup.6 Pa at 20.degree. C.) inner coating and a high modulus (more than 10.sup.8 Pa at 20.degree. C.) outer coating. Communication cable according to the invention can have low cabling loss, is adapted for array joining, can have high fiber density, and can advantageously be used in short-haul applications such as for metropolitan trunk lines or loop, as well as for long-haul applications.

Abstract: Optical pulses of nominal frequency f.sub.o and of predetermined repetition rate .tau..sub.M.sup.-1 can be generated by means of the induced modulational instability in single mode optical fiber, provided the fiber has anomalous dispersion at f.sub.o. A particularly advantageous method for generating such pulses that is capable of very high repetition rates is disclosed. The method involves coupling first and second cw or quasi cw optical radiation, of frequencies f.sub.1 and f.sub.2, respectively, into the optical fiber. Frequently one of the two radiations has much greater amplitude than the other. The resultant radiation in the fiber has frequency f.sub.o between f.sub.1 and f.sub.2, and is sinusoidally modulated with frequency .vertline.f.sub.1 -f.sub.2 .vertline.. Propagation of the resultant radiation through the fiber results in steepening and narrowing of the amplitude peaks. The length of the fiber typically is chosen such that, at the output, the pulse width .tau..sub.p <.tau..sub.

Abstract: The long term water intrusion resistance of cable splice systems that use a gelable encapsulant that is pressurized prior to geletion can be improved by providing pressurization means that maintain the pressure on the cured encapsulant above a given pressure p.sub.2 >p.sub.o, where p.sub.o is the ambient pressure. Absent such pressurization means, the pressure on the encapsulant typically decreases with time due to creep or relaxation of nominally rigid components, e.g., a polymeric closure around the encapsulated splice, or varies due to differential thermal contraction. The pressurization means comprises one or more energy storage elements, e.g., an elastic member such as a spring, or a volume of compressed gas.