651results about "Glass fibre drawing apparatus" patented technology

A method for forming an optical fiber includes drawing the optical fiber from a glass supply and treating the fiber by maintaining the optical fiber within a treatment temperature range for a treatment time. Preferably also, the fiber is cooled at a specified cooling rate. The optical fiber treatment reduces the tendency of the optical fiber to increase in attenuation due to Rayleigh scattering, and/or over time following formation of the optical fiber due to heat aging. Apparatus are also provided.

Suppression of stimulated Brillouin scattering (SBS) by broadening the energy spectrum of participating SBS photons and/or phonons is achieved in an optical fiber having a core with both radially nonuniform viscosity and CTE profiles provided by alternating layers of glass modifying dopants such as phosphorous and fluorine. The nonuniform thermal expansion and viscosity profiles impart a residual, permanent, nonuniform stress in the fiber. The SBS suppressing effect provided by the nonuniform stress can be controlled and enhanced by applying a uniform or nonuniform tensile force to the fiber as it is being drawn. A preform for the fiber is also disclosed.

Side-emitting step index fibers. Between core and cladding, the side-emitting step index fibers have scattering centers that ensure the coupling out of light from the fiber. The side-emitting step index fibers are produced by preforms that contain inlay rods, in which the scattering centers are embedded and which are applied to the outer region of the fiber core during fiber drawing. Alternatively, at least one inlay tube can be used.

A hole-assisted fiber comprises a core region and a cladding region, where the cladding region includes multiple substantially elliptical holes spaced apart from each other to surround the core region. The holes are filled with one of a gas and a liquid to form a low refractive index portion of the cladding region.

Apparatus and methods to fabricate a radiation hardened optical fiber from a preform are provided. Various parameters affecting the draw process are controlled to optimize the radiation resistance of the resulting fiber. An annealing zone may be provided to allow a drawn fiber exiting a primary hot zone to undergo an annealing process which may increase radiation resistance.

Microstructured optical fibre is fabricated using extrusion. The main design of optical fibre has a core suspended in an outer wall by a plurality of struts. A specially designed extruder die is used which comprises a central feed channel, flow diversion channels arranged to divert material radially outwards into a welding chamber formed within the die, a core forming conduit arranged to receive material by direct onward passage from the central feed channel, and a nozzle having an outer part in flow communication with the welding chamber and an inner part in flow communication with the core forming conduit, to respectively define an outer wall and core of the preform. With this design a relatively thick outer wall can be combined with thin struts (to ensure extinction of the optical mode field) and a core of any desired diameter or other thickness dimension in the case of non-circular cores. As well as glass, the extrusion process is suitable for use with polymers. The microstructured optical fibre is considered to have many potential device applications, in particular for non-linear devices, lasers and amplifiers.

A microstructured fiber having a cladding comprising a number of elongated features that are arranged to provide concentric circular or polygonial regions surrounding the fiber core. The cladding comprises a plurality of concentric cladding regions, at least some of which comprising cladding features. Cladding regions comprising cladding features of a relatively low index type are arranged alternatingly with cladding regions of a relatively high index type. The cladding features are arranged in a non-periodic manner when viewed in a cross section of the fiber. The cladding enables waveguidance by photonic bandgap effects in the fiber core. An optical fiber of this type may be used for light guidance in hollow core fibers for high power transmission. The special cladding structure may also provide strong positive or negative dispersion of light guided through the fiber-making the fiber useful for telecommunication applications.

An optical fiber preform 2 having a viscosity ratio Reta=eta0/etat of 2.5 or less between the core average viscosity eta0 and the total average viscosity etat is prepared, and is drawn by a drawing furnace 11 so as to yield an optical fiber 3, which is then heated to a temperature within a predetermined range so as to be annealed by a heating furnace 21 disposed downstream the drawing furnace 11. Here, upon annealing in the heating furnace 21, the fictive temperature Tf within the optical fiber lowers, thereby reducing the Rayleigh scattering loss. At the same time, the viscosity ratio condition of Reta<=2.5 restrains the stress from being concentrated into the core, thereby lowering the occurrence of structural asymmetry loss and the like. Hence, anoptical fiber which can reduce the transmission loss caused by the Rayleigh scattering loss and the like as a whole, and a method of making the same can be obtained.

An inner seal ring 16 is composed by connecting a plurality of inner seal ring pieces 16A, an outer seal ring 17 is composed by connecting a plurality of outer seal ring pieces 17A provided at an outer periphery of the inner seal ring 16, and a coil spring 18 is arranged at an outer periphery of the outer seal ring 17. The inner seal ring 16 and the outer seal ring 17 are piled for two or more stages, respectively. A connecting part of the inner seal ring pieces 16A and a connecting part of the outer seal ring pieces 17 are arranged not to overlap each other. An inner diameter of the inner seal ring 16 is variable in accordance with an outer diameter in vertical direction of a drawing-preform 1 by using a coil spring 18.

Carbon particles, such as, carbon fibrils and carbon nanotube molecules, are assembled into aligned fibers using processes derived from the processes used to manufacture optical fiber. More particularly, the carbon particles are embedded in glass, which is then drawn to align them. By aligned it is meant the axis along the longest dimension of each of the various particles in a local vicinity are substantially parallel.

An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index Δ_1MAX, and a inner cladding region having refractive index Δ_2MIN surrounding the core, where Δ_1MAX>Δ_2MIN.

In a method of producing a photonic crystal fibre, a preform (300) that includes holes is formed and the preform (300) is drawn into a fibre. The method includes the step of applying a pressure differential to certain of the holes to control changes in the fibre structure during the draw.

A method for forming an optical fiber includes drawing the optical fiber from a glass supply and treating the fiber by maintaining the optical fiber within a treatment temperature range for a treatment time. Preferably also, the fiber is cooled at a specified cooling rate. The optical fiber treatment reduces the tendency of the optical fiber to increase in attenuation due to Rayleigh scattering, and/or over time following formation of the optical fiber due to heat aging. Apparatus are also provided.

A method of fabricating a hole assisted fiber includes forming one or more slots in the perimeter of the cladding region. A tube is overcollapsed around the perimeter of the cladding region to form one or more channels, where the one or more channels bounded on one side by the overcollapsed tube. A fiber is drawn from the overcollapsed preform. An internal pressure is applied to the one or more channels during the fiber drawing step to form one or more holes of a pre-selected shape within the cladding region.

A method of manufacturing a holey fiber includes forming a preform and drawing the preform. The forming includes arranging a core rod at a center of a jacket tube and arranging capillary tubes having hollows around the core rod inside the jacket tube. The drawing includes heat melting the preform in a heating furnace while controlling at least one of a gas pressure to be applied to insides of the hollows of the capillary tubes, a temperature of the heating furnace, and a drawing speed, based on a structure of air holes to be formed in a first layer from the core region.

The invention relates to an optical fiber drawing method for a large-diameter optical fiber preform rod. The method comprises the following steps: continuously moving the large-diameter optical fiber preform rod downwards to enter an optical fiber drawing furnace through a lifter, heating and drawing to form a finished optical fiber, inputting protective gas into the furnace body through an extension pipe at the furnace bottom, allowing the protective gas to flow upwards, allowing the gas to flow out of a gas outlet of a gas guide disc, and allowing the protective gas input by the gas guide disc and a gas sealing cover to flow out of the gas outlet of the gas guide disc. The method has the advantage that the large-diameter optical fiber preform rod can be drawn to form the optical fiber with stable quality.

An optical fiber, which has a zero-material dispersion wavelength equal to or greater than 2 μm, and a high nonlinear susceptibility χ³ equal to or greater than 1×10⁻¹² esu, and uses tellurite glass having sufficient thermal stability for processing into a low loss fiber, employs a PCF structure or HF structure having strong confinement into a core region. This enables light to propagate at a low loss. The size and geometry of air holes formed in the core region, and the spacing between adjacent air holes make it possible to control the zero dispersion wavelength within an optical telecommunication window (1.2-1.7 μm), and to achieve large nonlinearity with a nonlinear coefficient γ equal to or greater than 500 W⁻¹ km⁻¹.

A method of making a multimode optical fiber is disclosed. In one embodiment the method includes calculating a core radius that maximizes the bandwidth of the multimode optical fiber wherein the effect of draw tension is accounted for. The embodiments herein illustrate how core radius can be tuned so the time delay of the outermost guided mode group is reduced. The resultant core radius may be targeted for a value off-nominal from what would be expected for a particular commercial optical fiber type.

A section of active optical fiber (11) which comprises an active core (1), an inner cladding layer (2) and an outer cladding layer (3). The diameter of said core 91) and the thickness of said inner cladding (2) change gradually along the length of said section of active optical fiber (11). This forms tapered longitudinal profile enabling a continuous mode conversion process along the length of the section of fiber (11). The method for fabricating a section of tapered active optical fiber comprises the steps of fabricating a perform for drawing active optical fiber from said perform, installing said perform into a drawing tower, drawing optical fiber in said drawing tower and altering at least one of the two parameters including the take-off perform speed and the take-up fiber speed during drawing of the optical fiber.

The invention relates to a wiredrawing method and a wiredrawing device for an outer diameter fluctuation optical fiber perform, particularly a large-size outer diameter fluctuation optical fiber perform. Compared with an existing wiredrawing method, the wiredrawing method has the different points that a radial seal adjustable device is arranged at a furnace mouth at the upper end of a heating cavity of a wiredrawing furnace; and in the wiredrawing process, the optical fiber perform is clung to the radial seal adjustable device, so that a radial gap between the optical fiber perform and the radial seal adjustable device, i.e. the difference between the outer diameter of the optical fiber perform and the seal aperture of the radial seal adjustable device, is kept in the range of 0 to 0.2mm. According to the invention, the radial gap between the large-size perform with nonuniform outer diameter variation and the radial seal adjustable device is always kept in a small allowable gap range or tends to zero in the wiredrawing feeding process, so that the wiredrawing quality is ensured and the technical difficult problem that the large-size outer diameter fluctuation optical fiber perform cannot be directly subjected to wiredrawing processing is solved; and the yield and the processing efficiency of optical fibers are further improved and the stringiness of the single perform is also improved, so that the optical fiber manufacturing cost is further reduced.