Long wavelength, low-loss optical waveguide
An optical fibre waveguide is disclosed of the type comprising an outer cladding layer, an axially disposed core of SiO2 doped with GeO2 and a first inner cladding layer of SiO2 doped with an oxide such as P2O5 for lowering the preform processing temperature. A second inner cladding layer of pure Si02 is disposed between the first inner cladding layer and the core to prevent P2O5 from diffusing into the core, thereby eliminating absorption losses from the P-O-H band in the 1.1-1.8 m region.
Publication number: EP0041864A3 | Search similar patents
Dielectric waveguide with chlorine dopant
An optical fiber of stepped index of refraction. The fiber core is of fused silica to which chlorine has been added to raise index and lower both its viscosity and hydroxyl ion content. Cladding composition is of either pure fused silica or fused silica to which a dopant, preferably fluorine, has been added.
Publication number: EP0181595A3 | Search similar patents
Multi-clad optical fiber lasers and their manufacture
An optical fiber is disclosed that can be used as an active medium in fiber lasers and/or fiber amplifiers, featuring a preferably rare-earth-doped silica active core surrounded by a pure or doped silica cladding layer (pump core). The pump core is surrounded by a doped or pure silica inner cladding for guiding pumping radiation within the pump core. Thus, the refractive index of the inner cladding is lower than that of the pump core. The fiber is surrounded by a protective coating made of polymeric material. One or more additional outer cladding layers, having refractive indexes lower than said inner cladding, may optionally be placed between the inner cladding and the protective coating to further protect the polymer coating from damage. Unlike the prior art, the protective coating does not serve as the only cladding, but is assisted by the inner cladding and optional outer cladding(s). The resultant fiber restricts radiation mainly to silica layers, thereby increasing the damage threshold and the applicable maximum pump power of the fiber.
Publication number: EP1599746A2 | Search similar patents
Single mode optical fiber
A single mode optical fiber of stepped index of refraction. Both core and cladding are fabricated of pure fused silica doped with a small base percentage of fluorine to substantially eliminate hydroxylions and reduce viscosity. In addition to the base amount of fluorine, the cladding contains a further amount for lowering its index of refraction relative to that of the core and for further reducing viscosity.
Publication number: EP0164681A3 | Search similar patents
Chalcogenide doping of oxide glasses
The present invention relates to a glass article for use as an optical waveguide fiber and more particularly to an optical waveguide fiber, the core of which is doped with a chalcogenide element to significantly increase the refractive index of the core. The subject of this invention is novel doped silica core compositions wherein a portion of the oxygen in the silica is replaced with either sulfur, selenium or tellurium using plasma enhanced chemical vapor deposition (PECVD). These compositions are designed to have higher refractive indices than silica, low coefficients of expansion, high optical transparency, and appropriate viscosity and softening points to make them ideal candidates for use as optical waveguide fibers.
Publication number: US2003161598A1 | Search similar patents
Chalcogenide doping of oxide glasses
The present invention relates to a glass article for use as an optical waveguide fiber (1), the core (4) of which is doped with a chalcogenide element to significantly increase the refractive index of the core (4). The subject of this invention is novel doped silica core composition wherein a portion of the oxygen in the silica is replaced with either sulfur, selenium or tellurium using plasma enhanced chemical vapor deposition (PECVD). These compositions are designed to have higher refractive indices than silica, low coefficient of expansion, high optical transparency and appropriate viscosity and softening points to make them ideal candidates for use as optical waveguide fibers.
Publication number: EP1183560A1 | Search similar patents
Single mode fibre and method of manufacture
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.
Publication number: US4327965A | Search similar patents
Cladding-pumped optical fiber and methods for fabricating
Disclosed is an optical fiber article for receiving pump radiation of a first wavelength for amplifying or generating radiation of a second wavelength. The optical fiber article includes a core for propagating light of the second wavelength. The core has a first index of refraction index and includes a rare earth material. A cladding surrounds the core and has a second index of refraction that is less than the first index of refraction. The outer circumference of the cladding can include a plurality of sections, where the plurality of sections includes at least one substantially straight section and one inwardly curved section. The optical fiber article can also include at least one outer layer surrounding the cladding, where the index of refraction of the outer layer is less than the second refractive index. Methods for producing the optical fiber article are also disclosed, as well as methods for providing a preform for drawing such an optical fiber article.
Publication number: WO02059660A1 | Search similar patents
Isotopically altered optical fiber
An isotopically-altered, silica based optical fiber is provided having lower losses, broader bandwidth, and broader Raman gain spectrum characteristics than conventional silica-based fiber. A heavier, less naturally abundant isotope of silicon or oxygen is substituted for a lighter, more naturally abundant isotope to shift the infrared absorption to a slightly longer wavelength. In one embodiment, oxygen-18 is substituted for the much more naturally abundant oxygen-16 at least in the core region of the fiber. The resulting isotopically-altered fiber has a minimum loss of 0.044 dB/km less than conventional fiber, and a bandwidth that is 17 percent broader for a loss range between 0.044-0.034 dB/km. The fiber may be easily manufactured with conventional fiber manufacturing equipment by way of a plasma chemical vapor deposition technique. When a 50 percent substitution of oxygen-18 for oxygen-16 is made in the core region of the fiber, the Raman gain spectrum is substantially broadened.
Publication number: EP1456695A2 | Search similar patents
Optical fiber amplifier
The present invention includes an optical fiber amplifier having a core and cladding layer. The core includes Zirconium dioxide (ZrO.sub.2) and a rare earth material. The core may be co-deposited with SiO.sub.2. A co-dopant of Ytterbium (Yb) may also be used. The optical fiber amplifier is well suited for use in the 1300 nm band when pumped with an optical source of appropriate power and frequency.
Publication number: US5805332A | Search similar patents
Improved optical fiber
An optical communications fiber is made from a core of high refractive index glass, a cladding of lower refractive index glass, and an edge cladding of a high refractive index glass. This optical fiber does not depend upon the refractive index of the polymeric coating to function properly, because the edge cladding refracts the errant light away from the core and cladding.
Publication number: EP0223466A3 | Search similar patents
Single mode optical fiber with improved bend performance
Methods and apparatus relate to optical fibers suitable for use in sensing applications exposed to radiation environments. The fibers include a core of pure silica or chlorine doped silica surrounded by a fluorinated silica cladding. These glasses for the core and cladding utilize dopants that resist radiation-induced attenuation. A two step process for forming the cladding can achieve necessary concentrations of the fluorine by performing a soot deposition process in a different environment from a consolidation process where the soot is sintered into a glass. Concentration of fluorine doped into the cladding layer enables obtaining a numerical aperture that confines a mono-mode of the fiber to resist bend-induced attenuation. Dimensions of the fiber further facilitate bending ability of the fiber.
Publication number: US2008273849A1 | Search similar patents
Long wavelength, pure silica core single mode fiber and method of forming the same
An optical fiber suitable to support single mode optical transmission at longer wavelengths (e.g., 1550 nm) is formed to comprise a pure silica core region and a “down doped” cladding layer. The core region is defined as having a diameter d and the cladding layer is defined has having an outer diameter D. In accordance with the present invention, single mode propagation will be supported when D/d>8.5, and is preferably in the range of 9–10.
Publication number: US6947650B1 | Search similar patents
Low-loss silica optical waveguides
Certain dopant materials, when present in a significant power-carrying portion of a silica-based optical waveguide fiber, are effective as intrinsic loss-reducing agents; the concentration of such dopant materials is at significantly lower levels as compared with levels used for producing a refractive index difference. Suitable in this respect are germania and phosphorus pentoxide as added to essentially pure silica or to silica containing other dopant additives such as, e.g., alumina or fluorine as may be used in a waveguiding core-cladding structure. Intrinsic loss in the vicinity of 0.2 dB/km is readily realized.
Publication number: US4770494A | Search similar patents
An optical fiber comprises a photosensitive core that includes a concentration of a first material that increases the refractive index of the core and a concentration of a second material that is other than boron and that reduces the refractive index of the core. A cladding is disposed about the core for tending to confine light to the core. The fiber also includes at least one longitudinally extending region having a thermal coefficient of expansion that is different from the thermal coefficient of expansion of the cladding. In another embodiment, the core includes a concentration of germanium and a concentration of boron. Also disclosed is a polarization-maintaining double-clad (PM DC) fiber comprising one or both of at least one circular axially extending stress inducing region(s) and an inner cladding comprising a circular outer perimeter. Fibers according to the invention can include a rare earth dopant for emitting light of a selected wavelength responsive to being pumped by pump light of a pump wavelength that is different than the selected wavelength.
Publication number: US2007089462A1 | Search similar patents