Abstract: Crystal grain size in a material is increased by scanning the material with an appropriately directed energy beam. Short-term oscillation in the scan, and a particular temperature gradient configuration in the wake of the scan, results in growth of large-grain crystallites.

Abstract: This invention is a technique for forming a specifically configured region of material which is rejected by an advancing freezing front within a melt. Resolidification of the molten material is effected in such a manner that liquid-solid interfaces intersect so as to control the shape and location of the rejected material which solidifies. Specific embodiments involve the formation of wires, tubes, or planes of enriched rejected material. Applications include the formation of enriched conductive material for making electrical contact between internal or external regions of electronic devices. Additionally, enriched material with etching properties different than that of the surrounding material may be formed and subsequently etched away in micro-machining applications.

Abstract: Aluminum metaphosphate optical fibers are disclosed. In a specific embodiment, aluminum metaphosphate, doped with from 10 to 30 mole percent of diboron trioxide, is found to yield an optical fiber which combines the desirable properties of both high numerical aperture and low material dispersion. The fiber is nonhygroscopic and has a high melting temperature. The index of refraction of the glass may be lowered by doping with silicon dioxide. Consequently, a graded fiber may be made by increasing the concentration of silicon oxide from the core to the cladding.

Abstract: A preform for fabrication of a glass fiber optical transmission line is prepared by chemical reaction of vapor ingredients within a glass tube. Reaction, which may be between chlorides or hydrides of, for example, silicon and germanium with oxygen, occurs preferentially within a constantly traversing hot zone. Flow rates and temperature are sufficient to result in glass formation in the form of particulate matter on the inner surface of the tube. This particulate matter deposits on the tube and is fused with each passage of the hot zone. Continuous rotation of the tube during processing permits attainment of higher temperatures within the heated zone without distortion of the tube.

Abstract: Conductor-clad composites are advantageously fabricated using molding compounds and associated processing techniques. The conductive cladding is applied and bonded to the composite during the molding process. The conductor-clad composite may be used as printed wiring board, and in this embodiment results in improved physical, chemical, mechanical, and electrical properties.

Abstract: This invention is a technique for fabricating optical fibers using thermophoretically enhanced particle deposition. In this process a cooling liquid such as water is poured over the substrate upon which deposition occurs in order to thermophoretically enhance the deposition. It has been found that despite the significant thermal shock that such water imparts to the tube, and despite previous difficulty with cracking because of thermal stresses which may develop, especially upon cooling, applicants have found that structural integrity may be maintained and enhanced deposition rates result.

Abstract: Aluminum metaphosphate optical fibers are disclosed. In a specific embodiment, aluminum metaphosphate, doped with from 10 to 30 mole percent of diboron trioxide, is found to yield an optical fiber which combines the desirable properties of both high numerical aperture and low material dispersion. The fiber is nonhygroscopic and has a high melting temperature. The index of refraction of the glass may be lowered by doping with silicon dioxide. Consequently, a graded fiber may be made by increasing the concentration of silicon oxide from the core to the cladding.

Abstract: A method of forming optical fibers with improved mode dispersion characteristics is disclosed. The technique involves differential mode-group delay measurement to optimize dispersion by means of appropriate index of refraction configurations. The differential delay measurement technique involves selectively launching light into the multimode fiber using a single mode fiber which is spliced to the multimode fiber using an adjustable splice including an index matching fluid.

Abstract: An optical fiber fabrication method and apparatus are described which are capable of producing reproducible and uniform layers of fiber quality glass. The formation of a saturated stream of glass precursor vapor by condensation allows for the delivery of calibrated predetermined quantities of vapor to an appropriate fiber fabrication apparatus, thereby permitting improved fabrication characteristics.

Abstract: The deposition of glass precursor particulates, during optical fiber fabrication, is rendered more efficient by increasing the thermal forces which play a significant role in directing the particulate material to an appropriate substrate. Specific embodiments are addressed to various optical fiber fabrication processes, all of which involve the formation of glass particulate material and its subsequent deposition on an appropriate substrate.

Abstract: The modified chemical vapor deposition process is practiced using an rf source as the external heat source. An rf plasma is thus established within a glass tube through which appropriate glass precursor vapors are passed. As a result of the ensuing chemical reactions, particulate material is formed within the tube and deposits on it. The hot plasma zone may be used to consolidate this particulate material into a transparent glass, and onto the interior wall of the tube. The tube is subsequently drawn into an optical fiber.

Abstract: A temperature gradient zone melting process is disclosed wherein the temperature gradient is established substantially across only the molten zone by preferentially heating the molten zone. In a specific embodiment, the mechanism for inputting heat to the molten zone involves exposing the substrate to optical radiation of a wavelength and magnitude for which the molten zone is absorptive and the remainder of the body is transparent. The molten zone thereby migrates through the body toward the source of optical radiation.

Abstract: A method of practicing the MCVD process is disclosed. In the inventive process, the core deposition is completed prior to completion of the cladding. An intermediate preform structure with a core-to-clad ratio greater than that desired in the ultimate fiber is consequently obtained. Subsequent to internal core deposition, additional material is added externally to complete the cladding thereby yielding an optical fiber preform with the desired core-to-clad ratio.

Abstract: An improved technique for growing native films on compound semiconductors is disclosed. In this technique, additional preferential chemistry is used in conjunction with prior art growth processes to eliminate what would otherwise be unreacted constituents in the native film. Films grown using this technique display improved electrical properties.

Abstract: A compact zone focusing lens system is provided for use as a photographic camera objective. In the system, a positive meniscus lens is mounted in registration with the larger opening of a truncated, opaque, open-ended cone section the apical end of which serves as a maximum system aperture stop. A transparent disk having a plurality of meniscus lens elements integrally molded therein is mounted so that its lens elements can be selectively rotated into alignment with the cone section apical opening to provide system focal lengths which are appropriate for sharply focusing objects located within different object distance ranges.

Abstract: A bistable liquid crystal twist cell is disclosed. The cell is characterized by at least two stable states which exist indefinitely as long as not external energy is applied to the cell. External energy is necessary only for switching the cell between the stable states. Cell configurations which permit the fabrication of patterned displays are additionally disclosed. Specific embodiments include new techniques for switching the cell between the stable states.

Abstract: A technique isdescribed for removing defects and disorder from crystalline layers and the epitaxial regrowth of such layers. The technique involves depositing short term bursts of energy over a limited spatial region of a material thereby annealing the otherwise damaged material and causing it to epitaxially regrow. Subsequent to the short term energy deposition, similar processing is sequentially effected on adjoining and overlapping regions such that a pattern is ultimately "written". This pattern forms a continuous region of essentially single crystal material.

Abstract: A new mode of optical annealing is disclosed wherein two different wavelength pulses are used to anneal a damaged semiconductor substrate. The first pulse may be of relatively weak intensity, but is strongly absorbed by the solid substrate. The second pulse, which is not strongly absorbed by the solid substrate when in the solid phase, is strongly absorbed by the substrate when in the molten phase. Exposure to the first pulse results in the melting of the substrate, which then becomes highly absorptive to light at the wavelength of the second pulse. Readily available laser sources which are generally not highly absorbed by the semiconductor in the solid phase may thus be efficiently utilized.

Abstract: A preform for fabrication of a glass fiber optical transmission line is prepared by chemical reaction of vapor ingredients within a glass tube. Reaction, which may be between chlorides or hydrides of, for example, silicon and germanium with oxygen, occurs preferentially within a constantly traversing hot zone. Flow rates and temperature are sufficient to result in glass formation in the form of particulate matter on the inner surface of the tube. This particulate matter deposits on the tube and is fused with each passage of the hot zone. Continuous rotation of the tube during processing permits attainment of higher temperatures within the heated zone without distortion of the tube.

Abstract: A new mode of operation of an optical cavity is disclosed. In this "regenerative pulsation" mode, a substantially nonvarying input yields an output consisting of a train of pulses. Fractional modulations exceeding 90 percent are demonstrated.