Abstract: An optical source is provided to the side of a fiber. The fiber is a single mode fiber which has a core and a cladding. The Bragg grating is written into the core at a low angle. Light emitted from the optical source is index-match coupled into the cladding by using an index matched element. Then, light is coupled into the fiber core along its length.

Abstract: An optical fiber suitable for the WDM transmission in the wavelength bands of 1.31 ?m and 1.55 ?m is provided. An optical fiber is characterized by a zero dispersion wavelength of longer than 1330 nm and shorter than 1430 nm, a dispersion of not less than 6 ps/nm/km and not more than 15 ps/nm/km at a wavelength of 1550 nm, a ratio of a dispersion to a dispersion slope of not less than 200 nm and not mare than 400 nm at a wavelength of 1550 nm, a dispersion of not more than ?1 ps/nm/km and not less than?8 ps/mn/km at 1300 nm, and a cutoff wavelength of 1300 nm or shorter.

Abstract: Systems and techniques are described for fabricating a low-loss, high-strength optical transmission line. In one described technique, a first fiber is spliced to a second fiber at a splice point. The spliced fibers are loaded into a heat treatment station, where a gas torch flame is used to thermally treat a splice region including the splice point, with the thermal treatment reducing splice loss between the first and second fibers. While heating the splice region, a dry gas is purged around the torch flame during the heat treatment process to avoid water at the surface of the spliced fibers. According to further described techniques, a purging gas is fed to the torch flame to purge dust particles from the flame, and after the heat treatment has been completed, the torch flame is used to restore the glass surface of the spliced fibers. Additionally described are torch assemblies for fabricating low-loss, high-strength optical fiber transmission lines.

Abstract: An optical fiber includes a first core having a relative refractive index difference of larger than 0.36%, and a cladding. The optical fiber has fiber cut-off wavelength ?c of more than 1350 nm, cable cut-off wavelength ?cc of less than 1285 nm, bending loss at a wavelength of 1625 nm of not more than 10 dB/km when wound at a diameter of 20 mm, transmission loss at a wavelength range of 1285 to 1625 nm of not more than 0.40 dB/km, transmission loss at a wavelength of 1383 nm less than transmission loss at a wavelength of 1310 nm, and difference in transmission loss at a wavelength of 1383 nm of not more than 0.04 dB/km before and after exposure to hydrogen. The lower bending loss of the optical fiber provides an optical fiber cable for use in a WDM transmission in wavelength range of 1285 to 1625 nm.

Abstract: An optical waveguide, such as an optical fiber, including a length of waveguide and at least one discrete longitudinal section having increased photosensitivity with respect to other portions of the waveguide.

Abstract: An optical waveguide having a working mode with a tailored dispersion profile, the waveguide including: (i) a dielectric confinement region surrounding a waveguide axis, the confinement region comprising a photonic crystal having at least one photonic bandgap, wherein during operation the confinement region guides EM radiation in a first range of frequencies to propagate along the waveguide axis; (ii) a dielectric core region extending along the waveguide axis and surrounded by the confinement region about the waveguide axis, wherein the core supports at least one guided mode in the first frequency range; and (iii) a dielectric dispersion tailoring region surrounded by the confinement region about the waveguide axis, wherein the dispersion tailoring region introduces one or more additional modes in the first range of frequencies that interact with the guided mode to produce the working mode.

Abstract: An optical fiber has three or four core slices including one or more buried slices and a raised central slice. The buried slice or each of the buried slices is very deeply buried. The fiber has a zero dispersion wavelength of less than 1 460 nm. It has a chromatic dispersion in the vicinity of 5 ps/nm.km and a dispersion slope in the vicinity of 0.03 ps/nm2.km at a wavelength of 1 550 nm.

Abstract: Into a mixture solution 2 of a high-refractive-index photo-curable resin A and a low-refractive-index photo-curable resin B, light capable of curing only the resin A is led through an optical fiber 1 so that a cured resin 211 of the resin A having a diameter substantially equal to the diameter of a core portion of the optical fiber is formed so as to extend from a tip of the optical fiber. Then, the residual mixture solution 2 is cured. In this manner, a module having the previously cured high-refractive-index resin 211 as an optical waveguide can be formed easily. On this occasion, the mixed state of the mixture solution 2 can be kept good enough to facilitate the formation of the high-refractive-index resin 211 when the solubility parameter ?A of the high-refractive-index photo-curable resin A and the solubility parameter ?B and volume fraction ?B of the low-refractive-index photo-curable resin B satisfy the following expression (4). |?A??B|<?7.5?B+6.

Abstract: An optical fiber characterized by a dispersion of not less than 2 ps/nm/km and not more than 10 ps/nm/km at a wavelength of 1550 nm, an effective area of 65 ?m2 or more at a wavelength of 1550 nm, a positive dispersion slope at a wavelength of 1550 nm, a zero dispersion wavelength outside the wavelength range of 1400 nm to 1460 nm, an absolute value of dispersion of not less than 2 ps/nm/km and not more than 10 ps/nm/km at a wavelength of 1400 nm, a cutoff wavelength of 1400 nm or shorter, and a transmission loss of 0.40 dB/km or less at a wavelength of 1400 nm is provided. By using the optical fiber of the present invention, the WDM transmission both in the 1.55 ?m wavelength band and in the wavelength range between 1400 nm to 1460 nm is realized.

Abstract: A DCF for compensating for the accumulated dispersion of a length of SMF in the C+L band window that includes a core surrounded by a cladding layer of refractive index ?c. The core includes at least three radially adjacent segments; a central core segment having a positive ?1, a moat segment having a negative refractive index ?2, and a ring segment having a positive refractive index ?3, wherein ?1>?3>?c>?2. The DCF exhibits a negative dispersion slope of between ?0.29 and ?0.43 ps/nm2/km at 1575 nm, and a total dispersion less than ?96 and greater than ?108 ps/nm/km at 1575 nm. A transmission link including the combination of a SMF and the present invention DCF is also disclosed.

Abstract: A photonic device suitable for being optically coupled to at least one optical fiber having a first spot-size, the device including: at least one photonic component; and, a graded index lens optically coupled between the at least one photonic component and the at least one optical fiber; wherein, the graded index lens is adapted to convert optical transmissions from the at least one photonic component to the first spot size.

Abstract: A network for distributing signals to a plurality of user having a distribution unit and a plurality of optical cables adapted to make the distribution unit communicate with the plurality of user equipment. In turn, each optical cable has an optical fibre having a core, a cladding and a predetermined simple refractive index profile ?n(r). Each optical fibre is adapted to guarantee a single-mode propagation at higher wavelengths than about 1260 nm and a few-mode propagation at about 850 nm, and each optical fibre has such refractive index profile ?n(r) as to guarantee macro-bending losses at 1550 nm that are less than about 0.5 dB and an intermodal delay ?? at 850 nm that is less than or equal to, about 1 ns/Km.

Abstract: The present invention relates to an optical fibre mainly consisting of silica glass, which fibre comprises: i) an inner core having a first refractive index n1 and a first diameter a; ii) an outer core surrounding the outer circumference of the inner core and having a second refractive index n2 and a second diameter b; and iii) a cladding surrounding the outer circumference of the outer core, which cladding has a third refractive index n3, wherein n1>n2>n3.

Abstract: Disclosed is an optical transmission line having a length L of 30 km to 150 km, preferably 30 km to 70 km, an absolute value of a dispersion not smaller than 8 ps/nm/km at a wavelength of 1.55 ?m at every point of the optical transmission line, a maximum accumulated dispersion not larger than 7.5×L (ps/nm) at a wavelength of 1.55 ?m, and a dispersion for the entire optical transmission line of ?5 to +5 ps/nm/km at a wavelength of 1.55 ?m. The optical transmission line is formed by, for example, combination of a positive dispersion optical fiber and a negative dispersion optical fiber.

Abstract: An optical network is formed of multiple H-tree distribution devices, separated into different waveguide layers. The optical network receives an input optical signal, such as an optical clock signal, and makes duplicate copies of that input signal. The duplicate copies are routed through the connected H-tree distribution devices, which are arranged to produce identical, synchronized copies of the clock signal. The network can take the form of a 1×2N device, where 2N represents the number of these output signals. The H-tree distribution devices forming the network are of varying size and may be formed in different waveguide layers with different index of refraction differentials between the H-tree devices and surrounding claddings. In some forms, the optical network is integrated with optical-to-electrical converters, i.e., photodetectors, which take the optical output signals and convert them to synchronized electrical signals that may be communicated to digital circuits.

Abstract: An optical fiber having a core that has a graded refractive index profile is disclosed. A clad surrounds the core and traps light within the core. A difference between differential mode delays (DMDs) at wavelengths of about 1300 nm and about 850 nm within the core is increased in a radial direction. The difference between the DMDs at both the wavelengths basically has a value equal to or less than 0.6 ns/km between a position corresponding to 50% of a radius of the core and a center of the core.

Abstract: Disclosed is a total dispersion and total dispersion slope compensating optical waveguide fiber. The refractive index profile of the compensating waveguide fiber includes a core region having a central segment and two surrounding annular segments. In an embodiment of the compensating waveguide fiber, a first clad layer adjacent the core region has a refractive index lower than that of a second clad layer adjacent the first clad layer. The optical waveguide fiber in accord with the invention has negative total dispersion and negative total dispersion slope over the operating window of the fiber to be compensated. The invention includes a compensated optical waveguide fiber span which includes a high performance waveguide fiber and a compensating waveguide fiber in accord with the invention.

Abstract: An optical filter comprising a slanted Bragg grating inscribed in an optical fiber portion comprising a core having a refractive index n1 and a radius Rcore and a cladding having an average refractive index n2 lower than n1 and a radius Rcladding, the core and the cladding of the fiber being doped with a photosensitive dopant in the fiber portion comprising the Bragg grating, which filter is characterized in that, in the fiber portion comprising the Bragg grating, the photosensitivity of the cladding is greater than the photosensitivity of the core and the cladding includes an index step area having a refractive index n3 greater than n2 and less than n1, said index step area having a width L defined by an inside radius Rs1 greater than or equal to the radius Rcore of the core and an outside radius Rs2 less than or equal to the radius Rcladding of the cladding.

Abstract: A system and method is disclosed for manufacturing single mode optical fiber which incorporates a spin in the molten fiber during manufacturing. The introduction of spin minimizes a form of distortion called polarization mode dispersion (PMD) and varying the spin, i.e. changing its characteristics, is known to further reduce PMD. However, introducing spin on a molten fiber may result in also introducing twist on the fiber. Twist is a non-permanent rotational force on the cooled fiber which causes stress and is to be avoided. A spin function is disclosed that not only contains a high degree of variability for reducing PMD, but also ensures that mechanical twist on the fiber is minimized, thus reducing stress on the fiber. The spin function modulates either the amplitude, frequency, or both, at the beginning of a cycle to minimize twist on the fiber.

Abstract: An index-guiding microstructured optical fiber, having a majority of the cross-section of the core and cladding regions occupied by voids. The voids are dimensioned such that an effective index of refraction of the cladding region is less than an effective index of the core region, the optical fiber propagating light by an index-guiding effect. The attenuation and dispersion characteristics of the microstructured optical fiber, when expressed in dB/km and ps/(nm-km), respectively, each decrease in approximate proportion to the percentage of cross-sectional area occupied by the voids. An appropriate void-to-cross-sectional area ratio may be selected so as to provide an optical communications link that provides substantially increased data throughput using today's installed base of conduit and communications relay stations.

Abstract: Optical fibers with high non-linearity and low dispersion suitable for the Raman amplification are offered. Their structural and characteristic specifics are as follows: first core 1 with ? profile surrounded with second core 2, further second core surrounded with cladding 5; setting first core 1 for no less than 1.8% of relative refractive index difference from cladding 5; setting second core 2 for no more than ?0.4% of relative refractive index difference from cladding 5, setting ? for 1.5 or larger, making second core 2 at least 2.2 times as large as first core 1 in diameter; and an effective area of no more than 15 ?m2, a dispersion slope of 0.05 ps/nm2/km or lower in absolute value, a dispersion of no less than 5 ps/nm/km and no more than 20 ps/nm/km, in absolute value, a cutoff wavelength of 1350 nm or shorter, and a bending loss of 5.0 dB or lower in a bending diameter of 20 mm, each at a wavelength of 1.55 ?m.

Abstract: The invention provides an optical fiber composition which has a high resistance to aging upon exposure to hydrogen. The inventive optical fiber does not require further treatment steps, such as passivation or hermetic coating, to meet specifications for hydrogen aging. The inventive optical fiber has a core glass composition with a germania doping concentration from 0% to 4% in weight. Decreasing the dopant concentration of germanium increases the resistance of the fiber to hydrogen by reducing the number of germanium defect sites in the core of the fiber. The optical fiber composition is advantageous for rare earth-doped fibers which are particularly sensitive to hydrogen aging.

Abstract: An optical fiber having an elevated threshold for stimulated Brillouin scattering is provided. The optical fiber includes a core and a cladding surrounding the core with both the core and the cladding designed to guide optical waves through the core while anti-guiding acoustic waves. Moreover, the optical fiber includes other features to alter the mode profile of the acoustic waves and/or to further promote their lateral radiation. For example, the optical fiber can include an irregular coating to alter the mode profile of the acoustic waves. In another example, the optical fiber can include a quarter wave layer surrounding the cladding to promote the lateral radiation of the acoustic waves. In order to further alter the mode profile of the acoustic waves, the cladding can also have a lateral thickness that varies irregularly in a lengthwise direction.

Abstract: A free space wavelength duplexed system includes first and second terminals. The first terminal includes an optical transmitter and an optical receiver. The optical receiver has a telescope, an optical to electrical converter and an optical amplifier coupled between the telescope and the optical to electrical converter. A method includes the steps of receiving a received optical signal through a telescope, diverting the received optical signal in an optical splitter into an optical amplifier, and transmitting a transmit optical signal through the optical splitter to the telescope. Another method includes the steps of receiving plural received optical signals through a telescope, diverting the plural received optical signals in an optical splitter into an optical amplifier, separating the plural amplified optical signals by wavelength, and transmitting plural transmit optical signals at distinct wavelengths through the optical splitter to the telescope.

Abstract: The present invention relates to an optical fiber comprising a structure enabling WDM transmissions by utilizing the whole wavelength range of 1300 nm to 1625 nm as a signal wavelength band. In the optical fiber according to the present invention, the transmission loss is 0.4 dB/km or less at a wavelength of 1310 nm, 0.4 dB/km or less at a wavelength of 1383 nm, and 0.3 dB/km or less at a wavelength of 1550 nm. The chromatic dispersion is 0.1 ps/nm/km or more but 5.5 ps/nm/km or less at a wavelength of 1383 nm, and 0.1 ps/nm/km or more but 16.5 ps/nm/km or less in the wavelength range of 1530 nm to 1565 nm. The cut off wavelength at a length of 22 m is 1300 nm or less, and the absolute value of dispersion slope in the wavelength range of 1300 nm to 1625 nm is 0.1 ps/nm2/km or less.

Abstract: A new class of optical fiber based thermal sensors has been invented. The new sensors comprise hydrogen-resistant optical fibers which are able to withstand a hot, hydrogen-containing environment as is often found in the downhole well environment.

Abstract: A photonic crystal fiber comprising: a core (20) having a refractive index; and a cladding region (10) at least substantially surrounding the core (20) and comprising a bulk material having a second refractive index that is higher that the first refractive index, the bulk material containing an arrangement of elongate, longitudinal holes that comprise hole material of a third refractive index that is lower than the first refractive index; such that an electromagnetic mode guided in the core (20) has an evanescent wave that becomes more closely confined to the vicinity of the core (20) as the wavelength of the electromagnetic mode is increased over a first range of wavelengths.

Abstract: A lens function-including optical lens according to the present invention is constituted by: at least one step-index optical fiber; and at least one gradient index optical fiber having an outer diameter equal to that of the step-index optical fiber and having a periodic length exhibiting a lens function, the gradient index optical fiber being joined or attached to an end surface of the step-index optical fiber. The present invention is especially effective in a single mode optical fiber which is typical of the step-index optical fiber. The gradient index optical fiber can be produced by an ion exchange method.

Abstract: An optical fiber for maximizing residual mechanical stress and an optical fiber grating fabricating method using the optical fiber are provided. The optical fiber includes a core formed of silica, for propagating light, and a cladding formed of boron-doped silica, surrounding the core. Alternatively, the optical fiber includes a core formed of phosphorous-doped silica and a cladding formed of silica, surrounding the core.

Abstract: The present invention provides an optical fiber equipped with a grating that functions as a narrow-band loss filter. The optical fiber has a core, an inner cladding, an intermediate cladding, and an outer cladding, which have refractive indexes n0, n1, n2, and n3, respectively, the refractive indexes having a relationship of n0>n3?n1n2. At least a part of the inner cladding has a grating. The refractive index of the intermediate cladding is lower than the refractive indexes of the inner cladding and the outer cladding such that a recession is formed in the refractive index profile of the clad. The grating is provided on the inner side relative to the recession.

Abstract: A single-mode fiber of increased core size consists of a “few-mode” fiber, of core size sufficient for guiding up to three high-order modes in addition to the fundamental mode, by interposing perturbations of such spacing along the fiber, as to selectively couple any such high-order modes to (unguided) cladding modes, thereby rejecting all but the fundamental mode. Unwanted coupling of the fundamental mode, leading to added fiber loss, is minimized by appropriate refractive index profile design.

Abstract: This invention relates to a method of making optical fiber having low polarization dependence and an acousto-optical filter with low PDL. A section of the fiber is heated and then allowed to cool. At least the heating is controlled to reduce stresses in a cladding layer surrounding a core of the interaction length after the interaction length is allowed to cool to reduce polarization dependence of the cladding layer. Preferably, at least time and temperature of heating is controlled.

Abstract: A filled-core optical fiber and method where the optical fiber is collapsed at opposing ends subsequent to the active optical material being introduced into the hollow core region. The collapsing-functions to “pinch off” the active material (which may be a liquid or solid) within the fiber structure and also collapse the cladding layer ring surrounding the core into a solid core region on either side of the active material. The filled-core fiber is then sealed and can be coupled to standard fiber using conventional splicing processes.

Abstract: A planar optical waveguide includes a layered film formed on a substrate, and an optical waveguide core formed in the layered film. A cross section of the optical waveguide core is substantially quadrilateral, and a dopant layer including refractive index-lowering molecules is provided around the optical waveguide core. The refractive index-lowering molecules included in the dopant layer are unevenly distributed in the optical waveguide core with a concentration that is higher toward outer sides and corners of the optical waveguide core, whereby a graded-index optical waveguide is constituted.

Abstract: An optical waveguide has a core, wherein the core is doped with laser-active ions, and also additionally doped with Ce.

Abstract: The invention relates to a waveguide comprising a transparent polymeric central core clad externally with one or more polymeric layers, at least one of the core or clad layer containing layered particles disposed in a polymeric binder, wherein a majority of the particles have a lateral dimension less than 1 micrometer.

Abstract: The present invention relates to a type of optical fiber grating having an azimuthal refractive-index perturbation. The optical fiber includes a fiber grating that has a plurality of grating elements formed therein. At least one of the grating elements has a spatially varying index of refraction that varies azimuthally about the centerline of the optical fiber. The fiber grating acts as a band-stop optical spectral filter. In addition, since fiber-cladding modes are weakly-guided modes, their power can be easily dissipated by scattering, bending, stretching, and/or rotating the optical fiber. Multiple configurations of these gratings within an optical fiber are given. Methodologies are given for the fabrication of these gratings. Devices are presented which can dynamically attenuate, tune, switch, or modulate the wavelength spectral characteristics of an optical signal.

Abstract: A photonic crystal optical fiber made up of an array of conventional hollow core optical fibers is disclosed. The array of optical fibers omits at least one fiber to form a central hollow core. The fiber works on the principle of two-dimensional photonic crystals to confine the radiation in a guided wave within the central hollow core. The fiber has a true photonic bandgap in which radiation of a particular energy or wavelength is totally forbidden, thereby providing a very high reflection coefficient to radiation incident the walls of the central hollow core over a select range of angles. The central hollow core allows for radiation propagation with minimal absorption.

Abstract: An optical transmission module includes a beam spot size expanding waveguide and a beam spot size reducing waveguide adjoining in the light propagating direction, or includes a beam spot size expanding waveguide, a beam spot size retaining waveguide and a beam spot size reducing waveguide aligning in the light propagating direction. Each waveguide has laminated core layers which are formed of materials of different refractive indexes.

Abstract: An apparatus and method for generating a mode-scrambled optical signal. A laser beam source directs an optical signal into a free end of a first segment of multimode fiber comprising a graded-index (GI) fiber core at an offset from the centerline of the core, generating an offset-launch condition. The first segment of multimode fiber is operatively coupled into a second segment of multimode fiber comprising a step-index (SI) fiber core. As the offset-launched optical signal passes through the first and second segments of multimode fiber, the optical signal is converted into a mode-scrambled optical signal having a substantially-filled numerical aperture.

Abstract: The present invention provides improved diffusion tips for optical fibers and methods of making the same. Nanoporous silica clad optical fibers are used to make fibers having integrally formed diffusion tips and diffusion tips that can be fused to other fibers. The disclosed diffusers can be fabricated to be cylindrical with light diffusing along its length, spherical with light radiating outwardly in a spherical pattern, or custom shaped to illuminate irregular surfaces or volumes. Gradient and step index properties can also be achieved. Several fabrication methods to achieve the desired effects are described. The problems in the prior art methods associated with epoxy, such as curing, bond strength, embrittlement, power handling limitations, and refractive index matching are avoided.

Abstract: An optical collimator structure comprising an optical fiber assembly of a plurality of unitary single-mode optical fibers each having a core, and a ferrule for supporting the optical fiber assembly inserted partially therein and bonded thereto, wherein the core has a graded index optical fiber bonded to the end face thereof, the graded index optical fiber along with the end portion of the core to which the graded index optical fiber is bonded being inserted in a hole of a capillary provided at an end of the ferrule, and the end face of the graded index optical fiber for emitting or receiving a beam of light has a tilt angle relative to the optical axis of the optical collimator structure.

Abstract: An optical fiber comprising a core and a cladding region which covers an outer periphery of the core, having a zero-dispersion wavelength in a wavelength range of 1.4 &mgr;m to 1.65 &mgr;m, and being in a single mode in that zero-dispersion wavelength, wherein GeO2 is doped in the core in a quantity such that a relative refractive index difference of the core becomes not less than 1.8%, the cladding region includes first, second, and third cladding regions, and a refractive index of the second cladding region is smaller than those of the first cladding region and the third cladding region.

Abstract: A single-mode fiber of increased core size consists of a “few-mode” fiber, of core size sufficient for guiding up to three high-order modes in addition to the fundamental mode, by interposing perturbations of such spacing along the fiber, as to selectively couple any such high-order modes to (unguided) cladding modes, thereby rejecting all but the fundamental mode. Unwanted coupling of the fundamental mode, leading to added fiber loss, is minimized by appropriate refractive index profile design.

Abstract: An optical waveguide fiber that simultaneously exhibits large effective area and good resistance to bend induced attenuation, as measured by any of the tests known in the art. The cut off wavelength is controlled to allow single mode operation over a wavelength range that extends from about 1340 nm to 1650 nm. The optical waveguide fiber refractive index profile is simple in design allowing cost effective manufacture.

Abstract: Optical fibers (220) are routed over a substrate (210), and an optical fiber wiring board (200) is thereby constructed. A relative refraction index difference &Dgr; of the optical fiber (220) is increased to be greater than a relative refraction index difference &Dgr;0 of a communication-dedicated single mode optical fiber, and a core diameter thereof is increased to be larger than a core diameter of the communication-dedicated optical fiber. Thereby, a mode field diameter thereof is set to be substantially the same as a mode field diameter of the communication-dedicated optical fiber.

Abstract: The present invention provides an optical fiber, comprising a core having an alpha parameter in the range of approximately 2 to approximately 8, a maximum index percent difference between the core and a cladding in the range of approximately 0.3% to approximately 0.5% and a core diameter in the range of approximately 6.0 to approximately 16.0 &mgr;m and a cladding. The optical fiber has a bandwidth of at least approximately 0.6 GHz.km at 850 nm, and is configured for multimode operation at a wavelength less than 1300 nm and single mode operation at a wavelength of at least approximately 1300 nm. The fiber also has significantly reduced intermodal noise. The present invention also includes a method of designing such a fiber, a fiber optic system provided such a fiber and a method of operating a fiber optic system with such a fiber.

Abstract: The present invention resides in an optical fiber able to form an optical transmitting line for wavelength division multiplexing transmission in a wavelength band of 1.5 &mgr;m using a Raman amplifier, and an optical communication system using this optical fiber. The optical fiber has an effective core area from 40 &mgr;m2 to 60 &mgr;m2 in a set wavelength band of at least one portion of a wavelength band of 1.5 &mgr;m; a dispersion value from 4 to 10 ps/nm/km at a wavelength of 1.55 &mgr;m; a dispersion slope set to a positive value equal to or smaller than 0.04 ps/nm2/km in a wavelength band of 1.55 &mgr;m; and a zero dispersion wavelength equal to or smaller than 1.4 &mgr;m. Further, a cutoff wavelength is set to be equal to or smaller than 1.5 &mgr;m at a length of 2 m, and a bending loss is set to be equal to or smaller than 5 dB/m at a diameter of 20 mm in the wavelength band of 1.5 &mgr;m.

Abstract: The present invention relates to a method and apparatus for manufacturing plastic optical transmission medium. The subject method and apparatus can produce a variety of optical transmission medium, including for example, graded refractive index polymer optical fiber, graded refractive index rod lens, and step index polymer optical fiber. The subject optical transmission medium have improved characteristics and efficiency, due, at least in part, to better control of the profile of the refractive index distribution and stable high temperature operation of the medium. High efficiency of manufacturing can be achieved by the subject method and apparatus which can permit continuous extrusion at high speed.

Abstract: A low attenuation optical fiber which falls within 2-14 ps/nm/km in absolute value of dispersion over the full wavelength range of 1530-1565 nm and no more than 0.25 dB/km of transmission loss at 1550 nm of wavelength at ordinary temperature and relative humidity, and still remains no more than 0.25 dB/km of transmission loss at 1550 nm or 1520 nm after its being long-enough exposed under ordinary atmospheric pressure consisting substantially of hydrogen; and which further comprises a polarization mode dispersion (PMD) of no more than 0.5 ps/km at a wavelength of 1550 nm and a loss increase of no more than 40 dB/m in a bending diameter of 20 mm.