Abstract: A single mode optical fiber comprises: (i) a segmented core having at least three segments and (ii) a silica based clad layer surrounding and in contact with the core, the clad layer having a refractive index nc. The first segment has a ?max% in the range of about 0.75 to 1.1, and ?0%?0.6?max %, and an outer radius r1 in the range of about 1.5 to 3.0 ?m. The second segment has a ?2% in the range of 0.00 to 0.15%. The third segment has a ?3% in the range of less than 0.35%, an outer radius r3 in the range of about 7 ?m to 11 ?m, a width w3 in the range of about 1.5 to 3 ?m, and volume V3<7% The refractive index profiles of the core segments are selected to provide: zero dispersion wavelength in the range of about 1565 nm to 1600 nm; total dispersion at 1550 nm in the range of about ?6 to ?0.5 ps/nm-km; and dispersion slope at 1550 nm is greater than 0.1.

Abstract: An optical transmission system comprising a laser light source arranged to emit light having a frequency ?; and an optical transmission line adapted to guide the light, wherein said optical transmission line includes a photonic bandgap optical fibre having a core guided mode at frequency ? and an attenuation band at a frequency of ?-13 THz. The optical transmission system suppresses Raman scattered light thereby allowing high optical powers to be transmitted through optical fibre.

Abstract: A photonic band-gap fiber comprises a first core having a refractive index that is not higher than a refractive index of a clad; a second core that is disposed so as to surround the first core and has a refractive index that is lower than the refractive index of the first core; a clad that surrounds the second core; and a periodic structure portion that is disposed in the clad in a vicinity of the second core and is constituted by high-refractive index portions that have a refractive index higher than that of clad and form the periodic structure, and the periodic-structure portion functions as a wave-length filter. By the function of the periodic structure portion as a wave-length filter, it is possible to reduce the propagation loss of the transmission wavelength and increase the propagation loss of the cutoff wavelength.

Abstract: The invention relates to a fiber structure (700), which has one or more refractive index disturbances (750 , 760) outside a fiber core (710) for discriminating one or more high order modes in the fiber structure. The invention also relates to a method for discriminating one or more high order modes, an arrangement having the high order modes discriminating fiber structure, and a device having the high order mode discriminating fiber structure.

Abstract: The subject invention pertains to a method and apparatus for multiplexing in optical fiber communications. The subject invention relates to a method and apparatus for spatial domain modulation in optical wavelengths. In a specific embodiment, the subject invention relates to a spatial domain multiplexer (SDM) for use with an optical fiber. Preferably, the input channels coupled into the fiber optic cable include collimated laser beams. The techniques of the subject invention can be utilized with single mode and multi mode waveguide structures, for example, single mode and multi mode optical fibers. The subject invention is applicable to step index optical fiber and to graded index optical fiber. Applications of the subject technology can include secure data links, for example, which can modulate data such that if the data is intercepted, the data cannot be interpreted. The subject methods and apparatus can also be used in conjunction with other multiplexing techniques such as time-domain multiplexing.

Abstract: A rare earth-doped core optical fiber of the present invention includes a core comprising a silica glass containing at least aluminum and ytterbium, and a clad provided around the core and comprising a silica glass having a lower refraction index than that of the core, wherein the core has an aluminum concentration of 2% by mass or more, and ytterbium is doped into the core at such a concentration that the light absorption band which appears around a wavelength of 976 nm in the light absorption band by ytterbium contained in the core shows a peak light absorption rate of 800 dB/m or less.

Abstract: A fiber optic article can comprise a core, an inner region disposed about the core and a cladding disposed about the inner region. The index of refraction of the cladding can be less than that of the inner region, and the index of refraction of the inner region can be less than that of the core. The fiber can include a second cladding disposed about the cladding, where the second cladding has an index of refraction that is less than the index of refraction of the cladding. The inner region can have a non circular outer perimeter that includes at least one inwardly oriented section. The article can be elongate along a longitudinal axis and can include at least one longitudinally extending region, such as a stress inducing region, for providing birefringence and the inwardly oriented region can face the longitudinally extending region. The fiber optic article can include active material for providing light responsive to the article receiving pump light, such as, for example, one or more rare earths.

Abstract: An optical waveguide substrate with an optical fiber fixation groove, including an optical waveguide which contains a lower cladding layer on a base substrate, wherein the lower cladding layer has an optical fiber fixation groove and a core groove, and a weir is provided between the optical fiber fixation groove and the core groove. The optical waveguide substrate with an optical fiber fixation groove is produced by forming a lower cladding layer on a base substrate using a male stamp produced from a female stamp and then successively forming a core layer and an upper cladding layer thereon. The stamp for use in such a production process includes concave portions or convex portions, corresponding to the optical fiber fixation groove and the core groove, as well as a convex portion or a concave portion corresponding to the weir. An opto-electronic hybrid integrated module includes the optical waveguide substrate with an optical fiber fixation groove.

Abstract: An optical fiber that is relatively insensitive to bend loss and alleviates the problem of catastrophic bend loss comprises a core region and a cladding region configured to support and guide the propagation of light in a fundamental transverse mode. The cladding region includes (i) an outer cladding region, (ii) an annular pedestal (or ring) region, (iii) an annular inner trench region, and (iv) an annular outer trench region. The pedestal region and the outer cladding region each have a refractive index relatively close to that of the outer cladding region. In order to suppress HOMs the pedestal region is configured to resonantly couple at least one (unwanted) transverse mode of the core region (other than the fundamental mode) to at least one transverse mode of the pedestal region. In a preferred embodiment, the fiber is configured so that, at a signal wavelength of approximately 1550 nm, its bend loss is no more than about 0.1 dB/turn at bend radius of 5 mm and is no more than about 0.

Abstract: The present invention relates to an optical fiber unit for air blown installation, which includes at least one optical fiber; a buffer layer surrounding the optical fiber and made of radiation curing acrylate; an outer layer surrounding the buffer layer and made of radiation curing acrylate; and a group of solid particles attached to a surface of the outer layer and having an average diameter of 80 to 140 ?m and a specific weight of 2 to 3 g/cc. Thus, there is provided a structurally stable optical fiber unit, which allows easy control of particles while the optical fiber unit is produced, and also has improved installation properties.

Abstract: A single-mode optical fiber includes a central core, an intermediate cladding, a depressed trench, and an external optical cladding. The central core has a radius r1 and a positive refractive index difference ?n1 with the optical cladding. The intermediate cladding has a radius r2 and a refractive index difference ?n2 with the optical cladding, wherein ?n2 is less than the central core's refractive index difference ?n1. The depressed trench has a radius r3 and a negative index difference ?n3 with the optical cladding. The optical fiber has a nominal mode field diameter (MFD) between 8.6 microns and 9.5 microns at a wavelength of nanometers, and at a wavelength of 1550 nanometers, the optical fiber has bending losses less than 0.15 dB/turn for a radius of curvature of 5 millimeters and cable cut-off wavelengths of less than or equal to nanometers.

Abstract: A single-mode optical fiber includes a central core, an intermediate cladding, a depressed trench, and an external optical cladding. The central core has a radius r1 and a positive refractive index difference ?n1 with the optical cladding. The intermediate cladding has a radius r2 and a positive refractive index difference ?n2 with the optical cladding, wherein ?n2 is less than ?n1. The depressed trench has a radius r3 and a negative index difference ?n3 with the optical cladding. At a wavelength of 1310 nanometers, the optical fiber has a mode field diameter (MFD) between 8.6 microns and 9.5 microns and, at a wavelength of 1550 nanometers, the optical fiber has bending losses less than about 0.25×10?3 dB/turn for a radius of curvature of 15 millimeters. At a wavelength of 1260 nanometers, attenuation of the LP11 mode to 19.3 dB is achieved over less than 90 meters of fiber.

Abstract: According to one example of the invention an optical fiber comprises: (i) a silica based core, said core having a core diameter greater than 80 ?m and a numerical aperture NA?0.24; and (ii) a silica based cladding in contact with and surrounding the core and having a second index of refraction n2, such that n1>n2; wherein the cladding includes B and F. Preferably the numerical aperture NA is at least 0.3.

Abstract: An optical fiber that transmits a signal light in a fundamental propagation mode has a cutoff wavelength longer than a wavelength of the signal light, a wavelength dispersion of the fundamental propagation mode of ?5 ps/nm/km to ?1 ps/nm/km at a wavelength of 1550 nanometers, an effective core area of the fundamental propagation mode larger than 45 ?m2 at the wavelength of 1550 nanometers, and a dispersion slope of the fundamental propagation mode smaller than 0.03 ps/nm2/km at the wavelength of 1550 nanometers.

Abstract: Disclosed is an optical fiber that includes an inner core having a concentration of at least one laser active material, the inner core being adapted to operate in a single mode manner; and an outer core disposed about the inner core having a concentration of at least one laser active material. The outer core being adapted to operate in a multimode manner, a cladding disposed about the outer core; and an outer cladding is disposed about the cladding adapted to substantially confine pump light within the cladding.

Abstract: A relative refractive index difference ?1 between a center core region and a cladding layer is 0.30% to 0.35%, a relative refractive index difference ?2 between an outer core layer and the cladding layer is ?0.10% to ?0.04%, and ?1:?2 is 2.5:1 to 7.5:1. A diameter of the center core region is 9.0 ?m to 10.5 ?m, and a ratio of diameters of the center core region and the outer core layer is 0.20 to 0.35. A cutoff wavelength is 1310 nm or shorter, a zero dispersion wavelength is 1285 nm to 1345 nm, and at a wavelength of 1550 nm, an MFD is 10.5 ?m or larger, a transmission loss is 0.185 dB/km or lower, and a bending loss is 15 dB/m or lower.

Abstract: An improved optical fiber achieves both reduced bending and microbending losses, as well as a much higher Brillouin threshold, as compared to standard transmission fibers. The optical fiber comprises a core including at least two dopants and having a refractive index difference ?n1 with an outer optical cladding, a first inner cladding having a refractive index difference ?n2 with the outer cladding, and a depressed, second inner cladding having a refractive index difference ?n3 with the outer cladding of less than ?3×10?3. The radial concentration of at least one of the core dopants varies continuously over the entire core region of the optical fiber.

Abstract: An optical fiber comprising: a glass core extending from a centerline to a radius R1; a glass cladding surrounding and in contact with the core, the cladding comprising: a first annular region extending from R1 to a radius R2, the first annular region comprising a radial width, W2=R2?R1, a second annular region extending from R2 to a radius R3, the second annular region comprising a radial width, W3=R3?R2, and a third annular region extending from R3 to an outermost glass radius R4; wherein (i) the core comprises a maximum relative refractive index, ?1MAX, relative to the third annular region; (ii) wherein the first annular region comprises a radial width W2; and (iii) the second annular region comprises a minimum relative refractive index, ?3MIN, relative to the third annular region wherein ?1MAX>?2MAX>?3MIN, and ?2MIN>?3MIN; and the core and the cladding provide a fiber with cable cutoff less than 1500 nm, dispersion at 1550 nm less than 12 ps/nm/km, effective area at 1550 nm greater than 60 ?m2, a

Abstract: The present invention is directed to a universal channel dispersion compensating fiber (CDCF) for WDM channel compensation that provides essentially zero dispersion slope over the wide wavelength band used in state-of-the-art transmission systems. It allows compensation of a large number of channels using a single fiber design. The improved optical fiber of the invention exhibits a dispersion slope at 1550 nm: <0.02 ps/nm2-km, preferably <0.01 ps/nm2-km, and a maximum variation of dispersion per km over the S-, C-, and L- bands of preferably less than 2.0 ps. In a preferred embodiment, the index profile of these fibers comprises a simple three layer design, which includes an up-doped central core, surrounded by a down-doped trench region, further surrounded by an up-doped ring region.

Abstract: A dispersion-shifted optical fiber (NZDSF) includes a central core (r1, Dn1), an inner cladding having at least three zones with a first intermediate cladding zone (r2, Dn2), a second ring zone (r3, Dn3) and a third buried trench zone (Wtr, Dnt). The buried trench zone has an index difference (Dnt) with the optical cladding between ?5·10?3 and ?15·10?3 and has a width (Wtr) between 2.5 ?m and 5.5 ?m. The present optical fiber, at a wavelength of 1550 nm, has reduced Rayleigh scattering losses of less than 0.164 dB/km, with limited bending losses.

Abstract: A rare-earth doped optical fiber that includes a core and one or more clad layers surrounding the core, in which the core has a rare earth dopant, and a relationship of Equation (1) is satisfied: 0 < ? r 0 r c ? D ? ( r ) · P p 2 ? ( r ) · P s 2 ? ( r ) ? r ? ? ? r ? r 0 r c ? D ? ( r ) · P p 2 ? ( r ) ? r ? ? ? r ? 0.35 ( 1 ) where Pp(r) represents an electric field distribution in an exciting wavelength, Ps(r) represents an electric field distribution in wavelengths of spontaneous emission and/or stimulated emission carried in the core, D(r) (mass %) represents a rare-earth dopant distribution, ro represents a core center, and rc represents a core diameter.

Abstract: The specification describes an improved optical fiber produced by a hybrid VAD/MCVD process. The core of the fiber is produced using VAD and the inner cladding layer has a depressed index and is produced using MCVD. In preferred embodiments, the optical power envelope is essentially entirely contained in VAD produced core material and the MCVD produced depressed index cladding material. Optical loss is minimized by confining most of the optical power to the VAD core where OH presence is low, as well as by maximizing the optical power in the un-doped silica region. The MCVD substrate tube material is essentially devoid of optical power.

Abstract: A POF includes an inner core having a refractive index distribution and an outer core provided on periphery of the inner core. A ratio Ra/Rb of an outer diameter of the inner core to the outer core satisfies 0.67?(Ra/Rb)?0.87 such that an outgoing beam from an end of the POF may have a parallel area of at least 200 ?m. Thus a space between the end for exiting the exit light and a light receiving device can be kept at least 200 mm without members or devices for collimating.

Abstract: A double-clad optical fiber includes a core, an inner cladding and an outer cladding of silica-based glass. The core may have a radius of less than about 5 ?m, a first index of refraction n1 and does not contain any active rare-earth dopants. The inner cladding may surround the core and includes a radial thickness of at least about 25 ?m, a numerical aperture of at least about 0.25, and a second index of refraction n2 such that n2<n1. The relative refractive index percent (?%) of the core relative to the inner cladding may be greater than about 0.1%. The outer cladding may surround the inner cladding and include a radial thickness from about 10 ?m to about 50 ?m and a third index of refraction n3 such that n3<n2. The relative refractive index percent (?%) of the inner cladding relative to the outer cladding may be greater than about 1.5%.

Abstract: Disclosed is an optical transmission fiber having reduced bending and microbending losses that is commercially usable in FTTH or FTTC transmission systems.

Abstract: An optical fiber is made of silica-based glass, and includes a core and a cladding. The optical fiber has a mode field diameter of 5.4 micrometers or larger at a wavelength of 1300 nanometers, transmits light with a wavelength of 1250 nanometers in a single mode, and has a bending loss of 1 dB/turn or smaller at a wavelength of 1300 nanometers when the optical fiber is bent with a curvature radius of 1 millimeter.

Abstract: A waveguide receiving light which propagates through free space is configured with a coupler and delivery fiber. The coupler, including a GREEN or multimode fiber, has a protective coating and so does the delivery fiber. Upon splicing of the coupler to the delivery fiber, the protective coatings of the respective coupler and delivery fiber are spaced apart exposing thus end regions of the respective coupler and fiber. The exposed regions are covered by a light stripper made of material having a refractive index which is substantially the same as or greater than that one of outer claddings. Accordingly, the light stripper minimizes the amount of light capable of coupling into the protective coatings of the respective delivery and coupler fibers enhancing thus a power handling capabilities of the waveguide.

Abstract: A technique is described for generating a cylindrically polarized beam, e.g., a radially or azimuthally polarized beam. An input optical fiber is provided that supports signal propagation in a fundamental LP01 mode. A mode converter device converts the fundamental LP01 mode into a higher-order LP11 mode output that includes a linear combination of modes, including cylindrically polarized TM01 and TE01 modes and mixed HE21 (even) and HE21 (odd) modes. The LP11 mode output propagates through a connected phase-engineered fiber having a refractive index profile that includes a steep refractive index step proximate to a peak amplitude of a mode intensity profile of the LP11 mode, such that at least one cylindrically polarized mode has an effective refractive index that is sufficiently separated from those of the mixed modes to allow for coupling to the at least one cylindrically polarized mode with minimal cross-coupling.

Abstract: An optical fiber, made of silica-based glass, comprising a core and a cladding. The optical fiber having a mode field diameter of 6.5 ?m or larger at a wavelength of 1300 nm, transmitting light with a wavelength of 1250 nm in a single mode, and having a bending loss of 1 dB/turn or smaller at a wavelength of 1300 nm when the optical fiber is bent with a curvature radius of 1.5 mm.

Abstract: A polymer clad optical fiber is provided in which, if the diameter of an inner core is taken as a1, and the diameter of an outer core is taken as a2, and if a ratio X (which=a22/a12) between a cross-sectional area of the inner core and a cross-sectional area of the outer core is within a range of 1.8?X?2.2, and if a relative refractive index difference between the inner core and the outer core is taken as ?1, and if a relative refractive index difference between the outer core and a cladding is taken as ?2, then for a parameter Y which is defined as Y=?1/?2, when a high temperature is taken as Ymax and a low temperature is taken as Ymin, a relationship is established in which, when X is within a range of 1.8?X?2.0, then 0.25?Ymin?0.84X?0.68, and Ymax is 0.25?Ymax?0.84X?0.68, and, when X is within a range of 2.0?X?2.2, Ymin is 0.48X?0.71?Ymin??2/9X+13/9, and Ymax is 0.48X?0.71?Ymax??2/9X+13/9.

Abstract: A method and apparatus using a gain medium in the form of a multiply clad gain fiber having an erbium-doped core. In some embodiments, aluminum and germanium are added to the silica core to make ?0 longer than the signal wavelength so the signal incurs normal dispersion. Optionally, a large-mode-area core amplifies primarily only one low-order mode because its NA is reduced by lowering the core's index of refraction (e.g., by adding fluorine) and/or by raising the index of the silica inner core (e.g., by adding germanium). Optionally, a thulium-doped region provides substantial loss at the first Raman-gain peak with respect to the signal wavelength but minimal loss at the signal or pump wavelength. Optionally, an inner cladding with a higher NA contains pump light within the outer boundaries of the cladding while allowing pump light to enter the core. In some embodiments, a triple cladding is provided.

Abstract: A dispersion compensating optical waveguide fiber that includes a core region surrounded by and in contact with a clad layer, wherein the respective refractive index profiles of the core region and the clad layer can be selected to provide, at a wavelength of 1550 nm, a total dispersion of less than ?25 ps/nm/km and a bend loss of less than 0.25 dB per turn on a 20 mm diameter mandrel. The dispersion compensating optical waveguide fiber can also have an effective area of greater than 25 ?m2. The dispersion compensating optical waveguide fiber may include a cladding layer having randomly dispersed voids situated therein.

Abstract: The present invention is directed to a light pipe having an improved structure of prisms. According to one embodiment of the present invention, a hollow light pipe comprises an inner-surface including a linear array of prisms; and a substantially smooth outer-surface, wherein a pitch of prisms in a first region is wider than a pitch of prisms in a second region. According to another embodiment of the present invention, a hollow light pipe comprises a hollow base pipe; and an insertion inserted into the base pipe and having a structured surface including an array of prisms, wherein a pitch of prisms in a first region is wider than a pitch of prisms in a second region.

Abstract: An optical waveguide device includes a lower cladding layer, a high refractive index region provided on the lower cladding layer, a pair of cores provided on the lower cladding layer on both sides of the high refractive index region, and an upper cladding layer provided on the high refractive index region and the pair of cores. One of the upper and lower cladding layers has a pair of band-shaped parts disposed between the high refractive index region and the pair of cores.

Abstract: In an optical fibre (1) for the transmission of high-power laser radiation, with a fibre core (2), with an inner fibre cladding (3) surrounding the fibre core (2) for carrying the laser radiation in the fibre core (2), with a first outer fibre cladding (4) surrounding the inner fibre cladding (3), which has a smaller refractive index than the inner fibre cladding (3) as a result of longitudinally aligned air-filled capillaries (5), and with a second outer fibre cladding (6) surrounding the first outer fibre cladding (4), wherein the first outer fibre cladding (4) has a capillary-free longitudinal section (8), the second outer fibre cladding (6) has according to the invention scattering centres (7) at least in the region of the capillary-free longitudinal section (8) for scattering the laser radiation emerging from the inner fibre cladding (3) along the capillary-free longitudinal section (8).

Abstract: Bend resistant multimode optical fibers are disclosed herein. Multimode optical fibers disclosed herein comprise a core region and a cladding region surrounding and directly adjacent to the core region, the cladding region comprising a depressed-index annular portion comprising a depressed relative refractive index which is spaced from the core at least 0.5 microns and less than 4 microns.

Abstract: An improved optical fiber achieves both reduced bending and microbending losses, as well as a much higher Brillouin threshold, as compared to standard transmission fibers. The optical fiber comprises a core including at least two dopants and having a refractive index difference ?n1 with an outer optical cladding, a first inner cladding having a refractive index difference ?n2 with the outer cladding, and a depressed, second inner cladding having a refractive index difference ?n3 with the outer cladding of less than ?3×10?3. The radial concentration of at least one of the core dopants varies continuously over the entire core region of the optical fiber.

Abstract: An optical fiber according to an embodiment of the present invention comprises: a glass core extending from a centerline to a radius R1 wherein R1 is greater than about 5 ?m; a glass cladding surrounding and in contact with the core, the cladding comprising: (i) a first annular region extending from the radius R1 to a radius R2, the first annular region comprising a radial width, W2=R2?R1, (ii) a second annular region extending from the radius R2 to a radius R3, and comprising a radial width, W3=R3?R2, and (iii) a third annular region surrounding the second annular region and extending from the radius R3 to an outermost glass radius R4; wherein the core comprises a maximum relative refractive index, ?1MAX, relative to the third annular region, and wherein ?1MAX is greater than about 0.1% and less than about 0.3%; the first annular region has a refractive index delta ?2(r) is less than about 0.

Abstract: An optical coupler includes a first optical port, a second optical port, a third optical port, and a fourth optical port. The optical coupler further includes a photonic-bandgap fiber having a cladding, a first core, and a second core. The cladding includes a material with a first refractive index and regions within the cladding. The regions have a second refractive index lower than the first refractive index. The first core is substantially surrounded by the cladding. The first core is optically coupled to the first optical port and to the second optical port. The second core is substantially surrounded by the cladding. The second core is optically coupled to the third optical port and to the fourth optical port. At least a portion of the first core is generally parallel to and spaced from at least a portion of the second core such that the first core is optically coupled to the second core. The first core, the second core, or both the first core and the second core is hollow.

Abstract: A silica-based optical fiber includes a core and a cladding that is formed on an outer circumference of the core. The core includes three or more layers including a layer doped with at least one of germanium and fluorine, and a concentration of the germanium or the fluorine in each of the layers is controlled in such a manner that a Brillouin gain spectral peak is spread into a plurality of peaks on a Brillouin gain spectrum. With this scheme, an optical fiber is provided, which has stable characteristics in the longitudinal direction, and which has a high SBS threshold so that generation of the SBS can be effectively suppressed.

Abstract: An optical fiber comprising: (i) a glass core (20) extending from a centerline and including a central core region (22) with an alpha value of less than 2, a first annular core region (24) surrounding the central core region (22), and a second annular core region (26) surrounding the first annular core region (24), wherein the second annular core region (26) has a higher maximum relative refractive index percent ?26MAX than that maximum relative refractive index percent ?24MAX of the first annular core region (24); and (ii) a glass cladding (30) surrounding and in contact with the core (20), the cladding comprising: (a) a first annular cladding region (32) extending from a radius R32 to a radius R34, (b) a second annular cladding region (34) extending from the radius R34 to a radius R36, (c) a third annular cladding region (36) surrounding the second annular region (34) and extending from the radius R34 to an outermost glass radius R36; wherein the core (20) comprises a maximum relative refractive index perce

Abstract: An optical fiber for producing laser radiation at a characteristic wavelength includes a first multimode core region and an active region embedded within the core region for producing radiation at the characteristic wavelength when pumped by pump radiation. The core region is adapted for guiding the laser radiation in a longitudinal direction of the fiber and is adapted for guiding pump radiation. The active region has a sufficiently small transverse dimension such that radiation produced in the active region is not confined to the active region.

Abstract: An optical fiber includes a core and a cladding, said cladding having a refractive index nc a first coating directly contacting the cladding of said fiber, said coating having a thickness of less than 10 microns, said coating having a refractive index delta %=100×(ni2?nc2)/2ni2 less than ?1 percent. In another aspect, an optical fiber includes a core and a cladding, said cladding having a refractive index nc, a first coating directly contacting the cladding of said fiber, said fiber comprising a glass diameter less than 100 microns, said coating having a thickness of at least 8 microns, said coating having a refractive index delta %=100×(ni2?nc2)/2ni2 less than ?1 percent.

Abstract: A double clad fiber includes a core, a first cladding provided so as to cover the core, and a second cladding provided so as to cover the first cladding. The second cladding has a plurality of pores extending in a length direction and arranged so as to surround the first cladding. In at least one fiber end, the second cladding has been removed by mechanical processing so that the at least one fiber end is formed by the core and the first cladding.

Abstract: A first polymerizable composition is poured into a pipe (30), then is polymerized to be a first layer (13). Next, a second polymerizable composition is poured into the pipe (30) and polymerized to be a second layer (14). These pouring and polymerizing processes are repeated to form an optical medium (10) including n-layers of polymer. Each layer is formed by polymerizing the polymerizable composition comprising same kinds of plural polymerizable contents as those in other polymerizable compositions for other layers. The layer at the inner side is formed from the polymerizable composition including larger ratio of a polymerizable content which has higher refractive index than that of at least another polymerizable content in the same polymerizable composition, compared with the polymerizable composition for forming the adjacent layer at the outer side. A difference of refractive indices between adjacent two polymer layers is at least 5×10?5 but less than 5×10?3.

Abstract: The present invention relates to an optical fiber for light pulse expansion in which the ratio (?3/?2) of the third derivative ?3 to the second derivative ?2 is negative, the absolute value thereof is large, and the absolute value of the second derivative ?2 is also large. Such an optical fiber comprises at least a central core portion having a maximum refractive index N1 and an outer diameter 2a, a depressed portion, provided on the outer periphery of the central core portion, having a minimum refractive index N2 and an outer diameter 2b, and a cladding portion, provided on the outer periphery of the depressed portion, having a maximum refractive index N3. The respective maximum refractive indices of the central core portion, the depressed portion and the cladding portion satisfy the relationship “N1>N3>N2”.

Abstract: A method for manufacturing a single mode optical fiber with a reduced PMD (Polarization Mode Dispersion), by drawing an optical fiber preform composed of a core and a clad surrounding the core, includes (a) heating the optical fiber preform to a high temperature using a furnace, and drawing an optical fiber from an outlet of the furnace at a linear velocity (Vf) of 500 mpm or above by means of neck-down drawing; and (b) impressing a spin on the optical fiber by means of a spin impressing device provided on a drawing path of the optical fiber, wherein a maximum spatial frequency of spin (y) impressed on the optical fiber satisfies the following equations Exp ? ( 24 ? t - 12 ) ? y ? - 20 × log ( V f 500 ) + 25 and t=(0.21×CladOval)+(0.04×CoreOval)+(0.17×ECC), where y is a maximum spatial frequency of spin [turns/m], Vf is a drawing velocity [mpm], CladOval is a clad ovality [%], CoreOval is a core ovality [%], and ECC is an eccentricity [?m].

Abstract: An optical fiber comprising: a silica based core having a first index of refraction n1; and at least one silica based cladding surrounding the core, the at least one silica based cladding comprising index lowering non-periodic voids containing a gas, wherein at least 80% of said voids have a maximum cross-sectional dimension of less than 2000 nm, and the NA of the fiber layer situated immediately adjacent to and inside said at least one silica based cladding is at least 0.2.

Abstract: Quasi-single mode optical waveguide fibers are disclosed that are bend resistant and capable of providing single mode transmission, for example at wavelengths greater than 1260 nm when the fundamental mode of optical energy is launched into the core of the fiber. Optical fiber line incorporating quasi-single mode optical waveguide fiber is also disclosed. Jumpers, or patchcords, utilizing quasi-single mode optical waveguide fiber are also disclosed herein.

Abstract: An optical fiber has a first mode field diameter in a dominant mode of an acoustic mode generated in the optical fiber different from a second mode field diameter in a light intensity distribution of the optical fiber. Furthermore, a transmission system is configured to perform an analog signal transmission, a baseband transmission, or an optical SCM transmission by use of the optical fiber.