Showing papers on "Hard-clad silica optical fiber published in 1999"

Grating resonances in air-silica microstructured optical fibers.

Abstract: We report what is believed to be the first demonstration of optical fiber gratings written in photonic crystal fibers. The fiber consists of a germanium-doped photosensitive core surrounded by a hexagonal periodic air-hole lattice in a silica matrix. The spectra of these gratings allow for a detailed characterization of the fiber. In particular, the gratings facilitate coupling to higher-order leaky modes. We show that the spatial distribution and the effective index of these modes are determined largely by the design of the lattice and that the grating spectra are unaffected by the refractive index surrounding the fiber. We describe these measurements and corresponding simulations and discuss their implications for the understanding of such air-hole structures.

Doped Mesoporous Silica Fibers: A New Laser Material

Abstract: 632 Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 1999 0935-9648/99/0806-0632 $ 17.50+.50/0 Adv. Mater. 1999, 11, No. 8 After this the polymer was rigid and could be peeled off carefully from the silicon master. The suspensions were prepared by adding powder to distilled water under constant stirring. The pH was always kept between 4 and 5 by dropwise adding a 2 M solution of hydrochloric acid (Titrisol, Merck, Darmstadt, Germany). Thereafter the suspensions were ball milled with alumina milling balls for 18 h. Two drops of 1-octanol (puriss, Fluka, Buchs, Switzerland) were added to reduce the surface tension of the suspension before degassing for 15 min at 90 mbar under constant rotation. For the formation of the ceramic samples a few drops of the particle suspension were poured onto the PDMS template and dried in room atmosphere. No separating agent was applied onto the mold. The suspension layer on the template structure was kept relatively thin (about 1 mm) in respect to its diameter (about 5 mm) to get quasi uniaxial shrinkage in the thickness direction to prevent high lateral shrinking rates during drying. After drying, the ceramic parts were carefully lifted from the molds and sintered. The PDMS templates were cleaned in an ultrasonic bath after processing and could be reused. The alumina samples were heated with 300 K/h to 1550 C and held there for 3 h. The boehmite samples were heated with 300 K/h to 300 C, then with 60 K/h to 600 C to allow the phase transition of boehmite from g-AlOOH to g-Al2O3 and then with 300 K/h to 1250 C and held there for 4 h. Suspensions of three powders with different particle sizes were prepared. Their properties are listed in Table 2. For a good pattern replication the suspensions needed to have a relatively low viscosity of about 0.5 Pa s which limits the amount of powder that can be dispersed. The achieved solids loadings decreased with decreasing particle size of the powders. Solids loadings in volume percent are shown in Table 2.

Photonic crystal fiber

Abstract: Disclosed is an optical waveguide fiber preform which is an assembly of one or more core rods (14) surrounded by a plurality of clad rods (10). The clad rods (10) have a central portion (12) and a surrounding layer (22), in which the refractive index of the central portion is lower than that of the surrounding layer. The preform is drawn into an optical waveguide fiber that has a two component clad layer. Proper choice of the central portion (12) and surrounding layer provide a waveguide fiber that is endlessly single mode. Alternative embodiments include fibers containing dopants that enhance fiber photosensitivity or which provide stress-induced or asymmetric-refractive-index-induced birefringence in the waveguide fiber.

Silica-based functional fibers with enhanced nonlinearity and their applications

Abstract: Silica-based optical fibers are now being used in various applications which utilize nonlinear effects in fiber. In addition to enhancing nonlinearity of optical fibers, tailoring chromatic dispersion is one of the important design issues in such applications. Highly nonlinear dispersion-shifted fibers have been developed, and a very compact wavelength converter module has been demonstrated by using the fiber. Dispersion-flattened and dispersion-decreasing fibers have also been proved to be highly effective for supercontinuum generation.

Optical fiber/waveguide illumination system

Abstract: A fiber optic illumination system includes a light source, a waveguide, and an optical fiber. One or more lamps and/or solid-state devices may be employed as the light source. The waveguide includes a straight collecting segment, a tapered condensing segment, and a straight homogenizing segment, may be fabricated from fused silica as a single monolithic component, conveys light from the light source to the optical fiber by transmission and/or internal reflection, and may be provided with UV and/or IR blocking filter coating(s). The optical fiber may be colorless or fluorescent optical fiber. Light transmitted by the optical fiber may be delivered to any one or more of a variety of light output devices, including diffusive flat panels, diffusive rods or wands, fluorescent light emitting converters, projectors, spectrum generators, and so on.

Silica–air photonic crystal fiber design that permits waveguiding by a true photonic bandgap effect

Abstract: A theoretical investigation of a novel type of optical fiber is presented. The operation of the fiber relies entirely on wave guidance through the photonic bandgap effect and not on total internal reflection, thereby distinguishing that fiber from all other known fibers, including recently studied photonic crystal fibers. The novel fiber has a central low-index core region and a cladding consisting of a silica background material with air holes situated within a honeycomb lattice structure. We show the existence of photonic bandgaps for the silica-air cladding structure and demonstrate how light can be guided at the central low-index core region for a well-defined frequency that falls inside the photonic bandgap region of the cladding structure.

Optical couplers for multimode fibers

Abstract: Optical couplers (48) functioning, for example, as fiber optic combiners or fiber optic splitters for multimode fibers are disclosed for coupling, for example, the light output of a plurality of multimode laser (44) sources into a multimode output fiber or fibers (30). Coupling combinations include multimode fibers to multimode fiber or fibers (MMFs/MMF(s)) or multimode fibers/single mode fiber to double clad fiber (MMFs/SMF/DCF). Improvements are disclosed in coupling efficiency and the power distribution uniformity of optical power into an output fiber, such as double clad fiber (20) inner cladding or multimode fiber core, from multiple multimode input fibers (30). Power distribution uniformity can be significantly improved by having the multimode fiber bundled region taper converging down to a minimum waist having a diameter, D0 (43), where the input light from the multimode input fibers (30) substantially fills the entire numerical aperture (NA) of an air-clad region of the couple, where NA ≈ 1, followed by an adiabatic diverging taper up to the nominal cladding or core diameter, Doutput (33), of the output fiber (20) or combined fibers.

Optical fiber nanometer-scale Fabry–Perot interferometer formed by the ionic self-assembly monolayer process

Abstract: The ionic self-assembly monolayer process is a novel technique that has already been used to deposit ultrathin films on glass, polymer, and silicon substrates of different sizes and shapes. This technique is presented as a new tool with which to apply coatings on optical fibers. A nanometer-scale interferometric cavity was built up at the end of an optical fiber with discrete thickness increments of 4.75??nm for a total thickness of 1 ?m. Theoretical and experimental aspects of the nanometer-scale Fabry–Perot cavity are described, and both theoretical and experimental results show good agreement.

Optically-induced growth of fiber patterns into a photopolymerizable resin

Abstract: We present evidence of optically-induced growth of fiber patterns into a photopolymerizable resin. Optical growth of a single or multiple fibers is achieved by focusing an ultraviolet (UV)-laser light into the photopolymerizable resin used. The fiber growth is due to an effect in which photopolymerization of the resin upon light irradiation produces an increase of the resin refractive index, the change of which, in turn, confines the light propagation into waveguide-type fiber structures. We have also observed that two optically grown independent fibers can merge to form a single fiber under specific conditions. We have studied the dependence of this optical growth of fiber structures phenomena on all the experimental parameters, including the numerical aperture (NA) of the lens used to focus the light, the light power, and the exposure time.

Etch-eroded fiber coupler for whispering-gallery-mode excitation in high-Q silica microspheres

Abstract: A simple and inexpensive technique for the excitation of whispering-gallery-modes in silica microspheres is presented. In this technique, the cladding of a single-mode optical fiber is etched chemically in order to expose the fiber's evanescent field. The cladding can be eroded partially, or removed completely with continued etching into the core. The etch-erosion procedure requires a minimum of specialized equipment and preparation time.

Optical fiber ribbon matrix material having optimal handling characteristics

Abstract: An optical fiber ribbon including a matrix material and one or more optical fibers disposed therein. The properties of the matrix material have been developed so that the optical fiber ribbon has optimal handling characteristics such as superior heat strip, encapsulation, easy peel and breakout, good fiber geometry and robustness. The optical fiber ribbon achieves optimal handling characteristics by including in the matrix material a polymer having a glass transition temperature of greater than 100° C., an elongation to break of greater than 15% and a rheological behavior wherein the onset of non-Newtonian behavior occurs at a shear rate of greater than 10 3 rad/sec.

Optical fibre and optical fibre device

Abstract: An optical fibre has a cladding layer surrounding a core, the cladding layer comprising at least a first, relatively inner generally cylindrical region, a third, relatively outer generally cylindrical region, and a second region disposed between the first and third regions, the second region having a higher refractive index than the first and third regions; and the peak difference in refractive index between the first cladding region and the core being less than about 0.0030.

Ring photonic crystal fibers

Abstract: A fiber optic waveguide is provided. The fiber optic waveguide includes a core region, and a cladding region surrounding the core region. The cladding region includes an inner cladding region and an outer cladding region. The inner cladding region has a lattice of ring structures. The core region is formed from a high index material and the cladding region is formed from materials producing an effective refractive index lower than the refractive index of the core region.

An optical fiber having an expanded mode field diameter and method of expanding the mode field diameter of an optical fiber

Abstract: The present invention is directed to a generally small mode field diameter ('MFD') optical fiber having a core bounded by a cladding, a cleaved end, and an expanded mode field diameter. The expanded MFD is formed by thermally diffusing one or more dopants in the core of the small MFD optical fiber using a highly localized heat source. The resulting adiabatic taper has an expanded MFD that is optimized for connection to another optical fiber having a larger MFD. The adiabatic taper is formed in the smaller MFD optical fiber by aligning and abutting the cleaved ends of two fibers having different MFDs to form a splice seam. The splice seam is offset a predetermined distance from the center of the region heated by a heat source to splice the fibers and expand the mode field diameters. As the mode field diameters expand, the splice loss across the splice is monitored. When the splice loss is at or sufficiently close to a target loss, heating is terminated, and the spliced optical fiber is cleaved where the MFD of the smaller MFD fiber portion of the spliced optical fiber is optically expanded to match the MFD of another optical fiber.

Bent silica fiber evanescent absorption sensors for near-infrared spectroscopy

Abstract: Silica optical fibers have been modified to improve their sensitivity as evanescent wave sensors for liquids. A section of fiber is stripped of its cladding and bent or coiled, which significantly increases the evanescent wave interaction with the surrounding environment. The effect of sensor shape, solute concentration, refractive index, and temperature on the sensor response is discussed.

Optical fiber grating package

Abstract: The invention describes a structure for an optical fiber grating package. The structure has a fiber grating that is mounted on a multi-layer metal plate. The fiber grating is formed on a fiber in the desired portion. Two ends of the fiber grating are secured to the two ends of the multi-layer metal plate. The multi-layer metal plate includes, for example, a bimetal plate and a thinner metal plate on the bimetal plate. The thinner metal plate is used to reduce the thermal expansion effect on the fiber grating. The structure further includes an adjusting plate located on the multi-layer metal plate on the side where the fiber grating is mounted so that the adjusting plate, serving as a pad, can lift the fiber of the fiber grating. The adjusting plate is also located a position between the grating portion of the fiber grating and one secured end of the fiber grating. As a result, a grating pitch of the fiber grating can be further precisely adjusted by shifting the relative location of the adjusting plate to causing a necessary tension of the fiber. The multi-layer metal plate with the fiber grating is held by a metal substrate.

Optical fiber having a bragg grating formed in its cladding

Abstract: A single mode optical fiber, having a pure silica core and a cladding, and having a Bragg grating in along a length of some of the cladding, providing reflectivity in some of the cladding but not in the core, and a method for making same. Because the core is pure silica, it is unaffected by exposure to ultraviolet light, and so the process of imprinting a Bragg grating does not affect the refractive index of the core. The portion of the cladding in which the Bragg grating is to be imprinted is a glass containing an index-lowering dopant, such as fluorine, as well as a photosensitizing dopant, such as germanium. Exposure to ultraviolet light therefore forms a Bragg grating in a portion of the cladding, but not in the core, providing reflectivity in the cladding, but not in the core. A second portion of cladding can also be provided, surrounding the portion doped with the photosensitizing dopant. The second portion of cladding is an outer cladding, surrounding the doped portion, which abuts the core.

All fiber gain flattening optical filter

Abstract: An all fiber optical filter (32) is formed by streching an optical fiber. The all fiber filter includes a core (34), an inner cladding (36), and an outer cladding (38). A core (34) index of refraction is greater than an outer cladding (38) index of refraction, and the outer cladding (38) index of refraction is greater than the inner cladding (36) index of refraction. The filter attenuates optical signals by transferring energy from the core (34) to the outer cladding (38) by evanescent coupling. The filter can be used for gain flattening in a WDM communication system (66) with EDFAs. The filter is manufactured by holding a length of an appropriate optical fiber (82) between two clamps (74, 76), heating the fiber (82) and stretching the fiber (82) until the desired filtering characteristics are achieved.

Optical module and a method for fabricating a same

Abstract: A semiconductor optical amplifier is mounted on a substrate which is provided for a package. Fiber blocks in which plural parallel internal optical fibers are supported are fitted to the package. The optical fibers are optically coupled with the semiconductor optical amplifier via optical waveguides formed on the substrate. V grooves for supporting the optical fibers which protrude out from the fiber block are formed on the substrate. Positionings of the optical fibers are performed by fitting the fiber blocks to the package so that end faces of the optical fibers butt against end walls of the V grooves.

Demonstration of an etched cladding fiber Bragg grating filter with reduced tuning force requirement

Abstract: A novel tunable fiber Bragg grating (FBG) filter with a chemically etched cladding has been demonstrated. By reducing the cladding diameter of a FBG through etching with HF, the tension tuning force can be lowered by over an order of magnitude. Wavelength tuning up to a failure point of 21.2 nm has been demonstrated along with repeated cycling over a 9 nm tuning range. Observations of increased coupling to resonant cladding modes in the etched FBG's are also noted.

Fiber coated with water blocking material

Abstract: The present invention relates to a fiber coated with a water blocking material that includes an essentially water free dispersion comprising a superabsorbent polymer and a dispersing medium. The fibers made according to this invention may be used, for example, as fiber reinforcing material used in the manufacture of cables, and in particular in yarns for fiber optical cables that use optical light wave guides for optical communication transmissions.

Photonic crystal fiber lasers and amplifiers for high power

Abstract: A photonic crystal fiber ( 10, 110 ) is provided for a laser/amplifier system including a guiding structure comprising a geometric array of axial passages ( 20, 120 ) formed along the length of the fiber ( 10, 110 ). More particularly, the guiding structure includes a central silica rod ( 14, 114 ) which is doped with a rare earth element for providing optical gain to the laser/amplifier. A plurality of second silica rods ( 16, 116 ) are disposed circumferentially about the central rod ( 14, 114 ). Each of the second rods ( 16, 116 ) includes an axial passage ( 20, 120 ) formed therethrough along the length of the fiber ( 10, 110 ). A reflective coating ( 22, 122 ) is deposited on an outboard surface of the array of rods ( 12, 112 ) to confine pumped light ( 30, 130 ) therein. The pumped light ( 30, 130 ) may be injected into the fiber ( 10, 110 ) from the side by focusing it through small holes ( 24 ) in the reflective coating ( 22 ) or by reflecting it off transverse Bragg gratings ( 56 ) written into a fiber pigtail ( 50 ) coupled to the fiber ( 110 ). The mode field diameter of the fiber ( 10, 110 ) is controlled by properly selecting the diameter and spacing of the passages ( 20, 120 ) in the second rods ( 16, 116 ).

Side pumped optical amplifiers and lasers

Abstract: An optical amplifier includes first and second optical fibers. The first optical fiber has a core, a first cladding surrounding the core and a second cladding surrounding the first cladding. The second optical fiber has an end physically coupled to a side portion of the first optical fiber. The end transmits light to the first cladding.

Method of applying a precursor to an assembled fiber bundle and fusing the bundle together

Abstract: Optical fiber bundles having high optical throughput can be produced with relatively high yield if gaps between fibers are eliminated by application of a particle-containing glass precursor material, exemplarily fumed silica in an aqueous medium. Manufacture of optical fiber bundles that comprise two or more fibers that each comprise a substantially planar surface (with the planar surfaces facing each other) is improved by application of a particle-free glass precursor material, e.g., partially hydrolysed tetramethyl orthosilicate, to the fiber bundle. After drying of the applied glass precursor material the fiber bundle is heated to fuse the fibers together.

Plastic optical fibers : principles, components, installation

Abstract: Physical Fundametals Overview of the Most Common Optical Fibers Construction and Manufacture of Plastic Optical Fiber Fiber Transmission Properties and Measurement Procedures Buffered Plastic Optical Fibers Plastic Optical Fiber Cable Design Test Procedures Transmitting and Receiving Components Connection Systems End-face Processing Procedures Passive Optical Components Using Polymer Clad Fibers for Longer Distances System Development Standardization Appendix Bibliography Index.

Optical fiber ribbon cables

Abstract: A fiber optic cable having optical sub-units each respectively including at least one optical fiber ribbon. The optical sub-units are removably connected together by a web of jacketing material. The optical fiber ribbons are generally twisted about their respective longitudinal axes by stranded strength fibers disposed about the optical ribbons. The fiber optic cable can be used as a stand alone component or, for example, in fan-out or break-out cables.

Optical fiber bundle having an aligned optical fiber array and method of fabricating the same

Abstract: An optical fiber bundle having an aligned fiber array includes a plurality of optical fibers each of which has first and second ends and an axial fiber center. The optical fiber bundle has a first common end proximate to which the optical fibers are secured in place by a first array fixture such that a fiber segment adjacent the first end of each optical fiber protrudes from the first array fixture. Each fiber segment of a selected plurality of fiber segments belongs to at least one microspacer neighborhood that includes at least two fiber segments secured in contacting engagement with a precision microspacer installed between the at least two fiber segments such that the axial fiber centers at the first ends of the at least two fiber segments are maintained in predetermined array positions with respect to one another.

Submarine optical cable, optical fiber unit employed in the submarine optical cable, and method of making optical fiber unit

Abstract: The present invention relates to a wide-band, low-loss, submarine optical cable excellent in productivity, an optical fiber unit employed in the submarine optical cable, and a method of making the optical fiber unit. The optical fiber unit employed in the submarine optical cable comprises a loose structure in which one or more coated optical fibers are accommodated together with a soft resin in a space formed within a plastic support. In particular, one or more compression members are embedded in the plastic support along the space accommodating the coated optical fibers. The compression members closely in contact with the plastic support prevents the shrinkage of the plastic support from occurring due to temperature changes before forming a cable utilizing the optical fiber unit. Preventing the shrinkage of the plastic support from occurring before forming the cable suppresses the increase in surplus length ratio of the accommodated coated optical fibers, thereby effectively restraining the transmission loss of the submarine optical cable from increasing due to the increase in surplus length ratio.