Showing papers on "Hard-clad silica optical fiber published in 1980"

Analysis of the backscattering method for single-mode optical fibers

Abstract: The theory of the backscattering method, which so far has been known only for multimode fibers, is extended to single-mode fibers. Under certain conditions the result of the present investigation is nearly the same as for multimode fibers although the theory in the latter case is based on a ray optical approach.

Fiber optic strain sensor.

Abstract: An optical fiber (10) having at least two cores (12 & 14) positioned in a common cladding (16) can be fabricated to be responsive to strain or hydrostatic pressure (20) but not to temperature through the selection of materials, spacing and shape of the cores and cladding in the fiber. Accordingly, the cross-talk between adjacent cores (12 & 14) in the optical wave-guide (10) can be optimized to respond to a change in hydrostatic pressure (20) or in unidirectional strain along the length of the fiber. The strain or pressure change, can be determined by measuring (22 & 24) the relative intensity of light emerging from the different cores of the fiber. A larger unambiguous range for strain or hydrostatic pressure (20) changes can be provided by a multi-core optical fiber embodiment.

Sum-frequency light generation in optical fibers.

Abstract: The generation in an optical-fiber waveguide of a spectral continuum spanning 29000 cm−1 from the near infrared to the ultraviolet is reported. A Q-switched and mode-locked Nd:YAG laser is used to excite the fiber. An unexpected phenomenon is the generation of sum-frequency light derived from the pump frequency and the characteristic Raman Stokes frequencies of fused silica. This light is observed as visible light in cladding modes of the fiber.

Polymer optical circuits for multimode optical fiber systems

Abstract: Polymer optical waveguides for multimode optical fiber systems have been formed by the selective photopolymerization method, and their waveguiding properties have been investigated. It is shown that the polymer optical waveguides match multimode optical fiber systems, with respect to guide dimensions and index differences, and have a transmission loss sufficiently low for circuit designs in the infrared region (0.19 dB/cm at 0.83 μm). In addition, effective applications of polymer optical circuits to compact optical dividers and lower loss couplers are demonstrated.

Optical fiber launch coupler

Abstract: A low-loss unidirectional optical coupler utilizing clad monofilament fibers of different diameters is provided by mounting each fiber on a curved surface, lapping the smaller (launch) fiber substantially tangentially to the curved surface until the core of the launch fiber has been lapped through to produce two elliptical flat surfaces, independently lapping the other (throughput) fiber tangentially to its surface to produce a fiber surface of substantially the same size as one of those produced on the launch fiber, aligning the throughput fiber surface with one of the launch fiber surfaces, and bonding them together.

Single mode optical fibers

Abstract: In a single mode optical fiber comprising a core made of glass and a cladding surrounding the core and made of glass, when a difference A between refractive indices n. and n2 of the core and cladding is expressed by the refractive indices n, and n2 are determined to satisfy a relation 1.0 < A < 3.6 and a diameter of the core is determined according to this value of A. When the refractive index difference A and the diameter of the core are determined in this manner, the optical fiber would have a wider band transmission characteristics than the prior art optical fiber, thus enabling higher degree of wavelength multiplexing.

Single-crystal AgBr infrared optical fibers.

Abstract: Single-crystal optical fibers up to 2 m long with well-defined crystal orientation have been grown from AgBr, which is transparent from ~0.5 to 25μm. The measured attenuation at 10.6 μm was ~2 × 10−2 cm−1, equal to the bulk loss in the raw material.

Microlenses for coupling single-mode fibers to single-mode thin-film waveguides.

Abstract: A new method has been devised for producing microlenses on the ends of single-mode optical fibers. A lens is formed by dipping the fiber end into a negative photoresist while the fiber core carries ≳0.1 mW of He–Ne laser light. The photoresist lenses require no developing or rinsing. The lenses are shown to transform the near-Gaussian beam emitted by the fiber into another near-Gaussian beam with a reduced waist diameter. The size of the new waist can be selected by varying the number of times the fiber is dipped into the photoresist. The waist reduction is shown to increase coupling into single-mode optical waveguides.

Fiber optic assembly for coupling an optical fiber and a light source

Abstract: A heat molded optical fiber interconnect molds one end of a plastic optical fiber around light emitting surfaces of a light source such as a light emitting diode to provide a highly efficient optical and mechanical coupling between the optical fiber and the light source. In one preferred embodiment an efficient interconnect for coupling large diameter optical fibers has a converging lens heat molded in the other end of the plastic optical fiber to efficiently couple light to another optical fiber or receiver.

Growth of Fiber Crystals for Infrared Optical Waveguides

Abstract: Modified floating zone technique is proposed to draw fiber single crystal for infrared optical waveguides Using this technique, KRS-5 fiber single crystals with 06~1 mm in diameter were prepared at the high growth rate of 05~3 cm/min up to 2m in length The fiber crystals have a circular cross-section and high plasticity to be bent freely at room temperature

Fluoride glass fiber for infrared transmission.

Abstract: Fluoride glass fibers were drawn from the GdF3-BaF2-ZrF4 glass rod by a conventional fiber fabrication technique. The homogeneous glass rods were prepared with the composition 2GdF37, 28BaF238 and 58ZrF469 (mol%) by casting in a brass mold. The transmission loss of the best fiber was as low as 0.48 dB/m, measured at 3.39 µm for a fiber several meters long ; further purification of starting materials should yield significant decreases in the transmission loss, approaching the intrinsic value.

Stress-induced birefringent single mode optical fiber and a method of fabricating the same

Abstract: The stress-induced birefringent single mode optical fiber includes an optical core having a high refractive index and a high thermal expansion coefficient. An arrangement formed from an optical material having a low refractive index and a low thermal expansion coefficient is disposed to engage the outer surface of the core tangentially at opposite ends of a diameter of the core to establish a stress therein. Air encompasses the remainder of the outer surface of the core to provide a light guiding cladding for the core and, hence, the fiber itself. The arrangement to establish the stress may include a pair of flat plates engaging the outer surface of the core tangentially which are entrapped in a circular tube which is concentric with the core such that air is entrapped between the plates and the circular tube to provide the light guiding cladding. Alternatively, an elliptical tube is provided to engage the outer surface of the core at the minor axis of the elliptical tube to provide the desired stress in the fiber. In this case air is enclosed in the elliptical tube to provide the light guiding cladding.

Fabrication method of single-mode optical fiber preforms

Abstract: A method of fabricating a single-mode optical fiber preform wherein a core torch produces fine glass particles eccentrically with respect to the center area of a flame stream, the core torch being so arranged as to blow the flame stream at an angle inclined to a seed rod. The porous glass body forming the core is grown on one end of the rod and in the direction of the axis of the rod. A cladding layer is formed on the periphery of the porous glass core body by at least one torch for forming the cladding. The obtained porous glass body is heated and vitrified into a transparent glass body, which is sealed in a silica tube for jacketting to form a single-mode optical fiber preform. At least one exhaust port is disposed within a distance of 1 mm to 50 mm from the periphery of the porous glass body and in the vicinity of the growing surface of the glass body to exhaust residual glass fine particles and undesired gases. A porous glass body having a diameter of 20 mm or less is easily formed. Single-mode optical fiber having a cladding-to-core-diameter ratio of 3 or more is fabricated by the VAD method. Accordingly, a long-length and low-loss single-mode optical fiber is mass-produced.

Ge-P-S Chalcogenide Glass Fibers

Abstract: Ge–P–S glass fibers have been drawn from glass rods prepared in sealed silica glass ampoules under a vacuum. The optical loss for the glass fiber has been as low as 0.4 dB/m at about 2.5 µm wavelength. The strong absorption peaks observed at 3 and 4 µm wavelengths originate from OH and SH impurities, respectively. The extrapolation of the measured loss curve in the near infrared region and the infrared absorption tail shows the minimum loss in the 5–6 µm wavelength region. Consequently, Ge–P–S glass fibers have the potential for low-loss optical fibers through reduction of OH and SH impurities.

Fiber optic wavelength demultiplexer

Abstract: An optical fiber wavelength demultiplexer including an optical fiber mounted and adhered to a curved surface having a clad single fiber core, a planar surface extending partially into and along the fiber through the cladding, a prism mounted on the surface having a reflective diffraction grating surface positioned to receive signals from the fiber travelling in one direction and demultiplex such signals, and an array of photodiodes mounted adjacent the prism to receive the demultiplexed signals.

Fiber drawing, coating, and jacketing

Abstract: The fiber drawing and coating process impacts strongly on the transmission and strength properties of optical fibers. Current practices which lead to realization of optimum fiber properties are discussed with reference to recent achievements and results in these areas.

A review of biconical taper couplers

Abstract: An optical coupler distributes light from a main fiber to one or more branch fibers. Optical signals can also be passed bidirectionally along a single fiber [1]. Usually couplers are passive devices which are attached to other components in a system by means of optical fiber connectors, or may be joined to them by splicing. Several basic coupler designs have been discussed in the literature, each having some advantages and disadvantages. The biconical taper coupler [2] consists of two fibers that are fused and subsequently tapered. These fibers may have step or graded index profiles. Beam-splitter types [3] (consisting of discrete components) are generally expensive. Mixing rods are simple and can be ruggedly constructed, but an extra 3dB loss above packing fraction loss is incurred when used with graded index fibers [4].

Coupling element for an optical transmission fiber

Abstract: A coupling element for coupling a laser radiation source to a monomode optical transmission fiber. The end of the fiber is monotonically flattened at a temperature at which the fiber core has a viscosity of between 107 to 108.5 poises. The fiber has a cladding glass chosen to have a viscosity of between 1010 -1011 poises at the flattening temperature. This causes the core glass to emerge in the form of a semi-ellipsoidal lens, when the fiber is flattened.

Coating material for optical communication glass fiber

Abstract: A coating material for optical communication glass fiber prepared by adding methylhydrogen polysiloxane or methylphenylhydrogen polysiloxane and a platinum catalyst to methylphenyl polysiloxane having both terminal groups vinyl-blocked. This coating material is excellent in applicability to glass fiber for optical communication, shows a rapid hardening rate, and can provide high grade glass fiber for optical communication having a hardened coating excellent in intimately adhering properties, flexibility, and uniformity.

Method for drawing high-bandwidth optical waveguides

Abstract: In a method for directly drawing a glass optical waveguide or waveguide blank from two or more reservoirs of molten glass wherein a relatively high refractive index glass core member is clad with a relatively low refractive index glass cladding, control over the refractive index variations occurring due to the migration of dopants between the core and cladding is obtained by providing one or more glass diffusion layers between the core and cladding.

Plastic clad optical fibers

Abstract: Plastic clad optical fibers and their method of production are disclosed. The fibers are formed of a core of doped silica and a silicone resin cladding.

Method of fabricating fatigue resistant optical fibers

Abstract: The fatigue resistant optical fiber is fabricated by producing an optical fiber having an electrically conducting surface, heating the produced optical fiber, and coating the heated optical fiber with a material impervious to water and water vapor.

Method of observing the core region of optical fibers and preforms

Abstract: A method of observing the core region of optical fibers and fiber preforms is disclosed comprising the step of inducing fluorescence in at least one of the index-modifying dopants present in the core being observed by illuminating said fiber/preform with radiation at the peak absorption wavelength for said dopant, and observing the region between the fluorescing edges of said fiber/preform. The core diameter can be determined by measuring the distance between said edges. This technique can be utilized to control the fiber pulling rate during fabrication.

High numerical aperture multicomponent glass fiber.

Abstract: High-numerical-aperture (N.A. 0.53) multicomponent glass fibers with 20 dB/km optical loss have been obtained. Glass containing BaO is most promising for fabrication of high-N.A. low-loss optical fibers over a wide wavelength region. The BaO-core glass/multicomponent-clad glass fibers show the following notable characteristics: relatively low optical loss in the 0.6-1.3-microm region, small N.A. wavelength dependence, high effective N.A., large bandwidth due to mode coupling, and high coupling efficiency to LED.

Effects of radiation on doped silica core optical fibres

Abstract: The effect of γ-radiation on SiO2/GeO2 core fibres for times between 10−3 s and 1 h have been measured. Between 10−1 s and 30 min, these fibres offer a large improvement over previously published data. Addition of P2O5 in the core of these fibres reduces the transient response at the expense of long-term response. The P2O5:GeO2 ratio controls the level of response.

Method for the manufacture of a multi-channel fiber optical waveguide

Abstract: A method for forming a preform which is subsequently drawn into a multi-channel fiber optical wave guide having a plurality of wave guide cores embedded in a cladding material, characterized by providing a quartz glass tube having an inner surface covered by a layer of cladding material, which in turn is covered by a layer of core material, removing strips of the core material to form parallel, symmetrically disposed strip-like portions of the core material, and heating the tube to cause the collapsing of the tube into the preform with buckling in the areas free of the strip-like portions of core material so that heat of the strip-like portions of core material become completely surrounded by cladding material and then subsequently drawing the preform into the optical fiber.

Single mode fibre and method of manufacture

Abstract: Single mode optical fibre for operation in the wavelength range 1.5 to 1.7 microns is made by first depositing an optically absorbing layer of silica doped with oxides of boron and/or phosphorus upon the bore of a silica substrate tube. The optical absorbing layer has a higher refractive index than silica, and on it is deposited a transparent optical cladding layer of matched index, and then a higher index optical core layer. The bore of the coated tube is then collapsed to form a solid cross-section optical fibre preform from which optical fibre can be drawn.

Method for fabricating a multiple-core optical fiber

Abstract: In order to produce multi-channel optical fibers, a quartz tube (1) on the inner side with a cladding and a core glass layer (2, 3) is first provided. Then, the number of cores corresponding number of strips (4, 5) removed the core glass layer (3). During the subsequent collapsing of the tube fall in the range of thin wall thickness together faster than in the remaining area, so that a number of strips (4, 5) corresponding number of separate cores (3a, 3b) is produced in the preform. The preform is drawn out in a known manner to the fiber.

Fiber optics heat formed assembly

Abstract: One end of a plastic optical fiber is attached to an LED by pressing a melted end of the optical fiber against the LED.

Method of and system for determining refractive-index profiles of optical fibers

Abstract: To facilitate determination of the refractive-index profile of an optical fiber by the near-field technique, the fiber to be examined is inserted into a body of transparent liquid held by surface tension in a surrounding capillary tube also made of light-transmissive material. The tube, which is axially coextensive with the inserted fiber, has a refractive index less than the minimum index of the fiber core and cladding whereas the liquid has a refractive index exceeding the maximum index of the fiber core.