Abstract: An optical fiber feedthrough assembly includes a glass plug disposed in a recess of a feedthrough housing. The glass plug may define a large-diameter, cane-based, waveguide sealed within the recess in the housing and providing optical communication through the housing. Sealing occurs with respect to the housing at or around the glass plug of an optical waveguide element passing through the housing by braze sealing to the glass plug and/or embedding the glass plug in a polymer bonded with the plug to form a molded body that is sealed in the housing by, for example, compression mounting of the molded body or providing a sealing element around the molded body.

Abstract: An optical component including an acceptance fiber, e.g. a photonic crystal fiber, for propagation of pump and signal light, a number of pump delivery fibers and a reflector element that reflects pump light from the pump delivery fibers into the acceptance fiber. An optical component includes a) a first fiber having a pump core with an NA1, and a first fiber end; b) a number of second fibers surrounding the pump core of the first fiber, at least one of the second fibers has a pump core with an NA2 that is smaller than NA1, the number of second fibers each having a second fiber end; and c) a reflector element having an end-facet with a predetermined profile for reflecting light from at least one of the second fiber ends into the pump core of the first fiber.

Abstract: The invention consists in an amplifying optical fiber comprising a core containing a dopant and a cladding, wherein said core comprises a monomode core intended to propagate an optical signal, quantum dots of a semiconductor material being disposed in or near said monomode core, and a multimode core surrounding the monomode core, intended to receive a pumping signal.

Abstract: 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.

Abstract: An optical fiber includes: a core (1) having an outer diameter (D1) of greater than or equal to 8.2 ?m and less than or equal to 10.2 ?m; a first cladding (2) surrounding the core (1) and having an outer diameter (D2) of greater than or equal to 30 ?m and less than or equal to 45 ?m; a second cladding (3) surrounding the first cladding (2) and having a thickness (T) of greater than or equal to 7.4 ?m; and a support layer (4) surrounding the second cladding (3). The relative refractive index difference which is the ratio of the difference between the refractive index of the support layer (4) and that of the second cladding (3) to the refractive index of the support layer (4) is greater than or equal to 0.5%.

Abstract: A photonic bandgap fiber includes a core formed by a hole at its center, an outer cladding formed around the core, and an inner cladding formed between the core and the outer cladding, in which a two-dimensional Bragg grating is formed by periodically arranging a medium having a different refractive index. An optical fiber is connected to the photonic bandgap fiber, which has wavelength dispersion equal to or larger than 0 ps/nm/km and smaller than wavelength dispersion of the photonic bandgap fiber and D/S value, which is obtained by dividing the wavelength dispersion by dispersion slope, larger than D/S value of the photonic bandgap fiber.

Abstract: Included among the many structures described herein are photonic bandgap fibers designed to provide a desired dispersion spectrum. Additionally, designs for achieving wide transmission bands and lower transmission loss are also discussed. For example, in some fiber designs, smaller dimensions of high index material in the cladding and large core size provide small flat dispersion over a wide spectral range. In other examples, the thickness of the high index ring-shaped region closest to the core has sufficiently large dimensions to provide negative dispersion or zero dispersion at a desired wavelength. Additionally, low index cladding features distributed along concentric rings or circles may be used for achieving wide bandgaps.

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.

Abstract: Various embodiments include large cores fibers that can propagate few modes or a single mode while introducing loss to higher order modes. Some of these fibers are holey fibers that comprising cladding features such as air-holes. Additional embodiments described herein include holey rods. The rods and fibers may be used in many optical systems including optical amplification systems, lasers, short pulse generators, Q-switched lasers, etc. and may be used for example for micromachining.

Abstract: An optical fiber, made of silica-based glass, comprising a core and a cladding, each of the optical fiber having a mode field diameter of 5.5 ?m or larger at a wavelength of 1100 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 1100 nm when the optical fiber is bent with a curvature radius of 2 mm.

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: A core part of a multimode optical fiber including the core part and a cladding part has a structure composed of a plurality of concentric layers in which a refractive index is decreased stepwise from a first core layer as an innermost layer to a third core layer as an outermost layer. The structure having the plurality of layers is formed by adjusting a quantity of addition of fluorine to silica glass. Fluorine is added to the cladding part so that a refractive index is lower than that of the third core layer as the outermost layer of the core part.

Abstract: An optical fiber transmits at least a signal light having a wavelength of 1550 nanometers in a fundamental propagation mode. The optical fiber has a cutoff wavelength equal to or longer than a wavelength of 1550 nanometers, a wavelength dispersion in the fundamental propagation mode at the wavelength of 1550 nanometers larger than 0 ps/nm/km, and a dispersion slope in the fundamental propagation mode at the wavelength of the signal light equal to or smaller than ?0.05 ps/nm2/km.

Abstract: Optical waveguide fiber that is bend resistant and single mode at 1260 nm and at higher wavelengths. The optical fiber includes a core of radius R1 and cladding, the cladding having an annular inner region of radius R2, an annular ring region, and an annular outer region. The annular ring region starts at R2, and the ratio R1/R2 is greater than 0.45.

Abstract: A polarizing film is made of multilayer polarizing fibers embedded within a matrix. The fibers are formed with layers of at least a first and a second polymer material. Layers of the first polymer material are disposed between layers of the second polymer material. At least one of the first and second polymer materials is birefringent. In some embodiments the thickness of the layers of at least one of the materials varies across the fiber, and may include layers are selected as quarter-wavelength thickness for light having a wavelength of more than 700 nm.

Abstract: A large-mode-area (LMA) optical fiber (10) that operates as a single-mode optical fiber. The optical fiber includes a core region (20) surrounded by an inner cladding (32), which in turn is surrounded by an outer cladding (40). The inner cladding includes at least one up-doped ring region (32R1). The ring region is configured to form a large attenuation differential between the higher-order modes and the fundamental mode so only that the fundamental mode remains traveling in the optical fiber. If necessary, the optical fiber can include a bend (10B) having a select “resonant” bend diameter (DB) that increases the relative attenuation of the fundamental and higher-order modes. The optical fiber supports an effective mode field diameter (MFD) of up to 40 ?m to 50 ?m. As a result, detrimental non-linear effects are suppressed, which allows the optical fiber to carry substantially more optical power than conventional LMA optical fibers.

Abstract: According to some embodiments an optical waveguide fiber comprises: (i) a Ge free core having an effective area of 90 ?m2 to 160 ?m2, at a 1550 nm wavelength, and ? value 12???25, said core comprising: (a) a central core region extending radially outwardly from a centerline to a radius 0 ?m?r0?2 ?m, and having a relative refractive index percent profile ?0(r) in % measured relative to pure silica, wherein ?0.1%??0(r)?0.1%, wherein the central core region has a maximum relative refractive index percent, ?0MAX, (b) a first annular core region surrounding and directly adjacent to the central core region and extending to an outer radius r1, wherein 4.8 ?m?r1?10 ?m, and having a relative refractive index percent profile, ?1(r) in % measured relative to pure silica, and a minimum relative refractive index, ?2MIN, and the relative refractive index measured at a radius r=2.5 ?m being: ?0.15??1(r=2.5 ?m)?0, and ?0MAX??1(r=2.

Abstract: An optical device includes an optical material comprising active dopant ions and absorber dopant ions spaced apart from the active dopant ions. The active dopant ions are provided to absorb a first radiation and convert a portion of the first radiation into sensible heat. A concentration profile of the absorber dopant ions is selected to absorb a second radiation different from the first radiation and optionally the first radiation in at least one direction of the optical material so as to control a refractive index profile in the at least one direction of the optical material.

Abstract: A single-mode optical fiber possesses, at a wavelength of 1550 nanometers, an effective area greater than about 90 ?m2 without degradation of the optical fiber's other optical parameters. The single-mode optical fiber includes a central core, a first intermediate cladding, a second intermediate cladding, and an outer cladding. The optical fiber also has a cable cut-off wavelength of less than 1260 nanometers. Additionally, at a wavelength of 1310 nanometers, the optical fiber possesses a mode field diameter of between about 8.6 microns and 9.5 microns. Furthermore, the optical fiber possesses a zero chromatic dispersion wavelength of between about 1300 nanometers and 1324 nanometers and, at the zero chromatic dispersion wavelength, a dispersion slope of less than 0.092 ps/(nm2·km).

Abstract: An active multimode optical fiber consisting of a first core section (11), a thin barrier layer (12) material having a thickness (d2) and a lower refractive index than that of the first core section by an index difference (?n), a second core section (13) having a refractive index equal or higher than that of the first core section, and a cladding (14) having an index lower than that of the first core section. Said index difference and said thickness are selected so that a fundamental core mode couples less strongly with said cladding modes than higher order core modes. A scheme of changing the symmetry of the fiber for reduced sensitivity of the fundamental mode of the first core section to resonance effects.

Abstract: A core region is doped with an impurity. A first cladding region is formed in a layered structure around the core region, including a microstructure. A second cladding region is formed in a layered structure around the first cladding region, including a homogeneous material. A relative refractive-index difference ?1 between the core region and the second cladding region is equal to or more than 0.4% and equal to or less than 1.0%.

Abstract: The present invention is a splicing structure of optical fibers for fusing a double clad fiber and a single clad fiber, the splicing structure is provided with a block covering a fusion splicing point of the double clad fiber and the single clad fiber, and which is made of a highly thermal conductive material.

Abstract: Provided is an optical fiber that has a small bending loss, can be securely prevented from being fractured due to accidental bending during installation or other operations, and is compliant with the G. 652 standard. An optical fiber 1 includes a core 11, a first cladding 12, a second cladding 13, and a third cladding 14. The relative refractive index difference ?1 of the core 11 is in the range of 0.3% to 0.38%, the relative refractive index difference ?2 of the first cladding 12 is equal to or smaller than 0%, and the relative refractive index difference ?3 of the second cladding 13 is in the range of ?1.8% to ?0.5%. The inner radius r2 and the outer radius r3 of the second cladding 13 satisfy the expression “0.4r2+10.5<r3<0.2r2+16”, and the inner radius r2 of the second cladding 13 is equal to or greater than 8 ?m. The bending loss at a wavelength of 1550 nm and at a radius of curvature of 7.5 mm is smaller than 0.

Abstract: A coated optical fiber capable of transmitting high-power light, which is an optical fiber having an outer surface coated with a coating material, is characterized in that the coating material is made of a transparent UV curable resin so as to prevent the coating material from absorbing light leaked outside from the optical fiber to generate heat. Further, a light transmitting method is characterized in that a fiber fuse propagation threshold which is a minimal light output required for fiber fuse propagation is obtained and a transmitted light output is controlled so that the transmitted light output becomes smaller than the fiber fuse propagation threshold.

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: The present invention relates to a single mode optical fiber comprising a first central region having a radius r1, a maximum refractive index value n1 and at least one second ring surrounding said first central region, which second ring has a radius r2 and a minimum refractive index value n2, wherein n2<n1. The present invention furthermore relates to an optical communication system for multi-channel signal transmission.

Abstract: An optical fiber includes: a first core portion doped with rare earth ions; a second core portion having a lower refractive index than that of the first core portion, provided along an outer circumference of the first core portion, and doped with the rare earth ions; and a clad portion having a lower refractive index than that of the second core portion and provided along an outer circumference of the second core portion, and is configured such that a concentration of the rare earth ions added to the second core portion is higher than that to the first core portion. With this configuration, it is possible to suppress an amount of FWM crosstalk in an optical amplification by decreasing the length of a fiber while alleviating efficiency deterioration due to concentration quenching.

Abstract: Disclosed is a method of producing a planar multimode optical waveguide by direct photo-patterning and, more particularly, to an optical waveguide material and a method of producing the same. It is possible to control the refractive index of the optical waveguide, and the optical waveguide has a desirable refractive index distribution throughout different dielectric regions. In the method, it is unnecessary to conduct processes of forming a clad layer and of etching a core layer, thus a production process is simplified. The method comprises coating a photosensitive hybrid material having a refractive index or a volume changed by light radiation, in a thickness of 10 microns or more, and radiating light having a predetermined wavelength onto the coated photosensitive hybrid material to form the multimode optical waveguide due to a change in refractive index of a portion onto which light is radiated.

Abstract: A device for coupling multimode pump light and a laser signal into or out of a cladding-pumped fibre laser is disclosed, comprising an output optical fibre, a substantially un-tapered feed-through optical fibre, an annular waveguide having a tapered section, and a plurality of multimode pump fibres such that: the signal feed-through fibre is located within the annular waveguide; the signal feed-through fibre is fused into the annular waveguide in the tapered section so that the annular waveguide becomes an additional cladding layer of the feed-through fibre; the end of the feed-through fibre that is fused into the annular waveguide is optically coupled to the output optical fibre; the multimode pump fibres are optically coupled to the annular waveguide in the un-tapered section. Methods of forming the device are also disclosed.

Abstract: An optical component includes at least one light-guiding element with a side surface extending between incident and emission faces between which light that is introduced into the incident face can propagate by internal reflection. Disposed over at least a portion of the side surface of at least one of the at least one light-guiding elements is an extramural absorption material that is configured to selectively absorb “stray light” that enters the incident face of the light-guiding element, but which exists through the side surface instead of the emission face. The absorption material is fabricated, at least in part, from an electro-chromic material exhibiting a translucency that is selectively adjustable in response to changes in at least one of (i) electrical current applied through at least a portion of the absorption material and (ii) an electrical potential difference applied between disparate locations within the absorption material.

Abstract: An optical fiber in which the macro-bending loss is lowered while an MFD is maintained large, and a waveguide including the optical fiber. The optical fiber includes a core region doped with an impurity; a first cladding region formed as a layer around the core region and including holes as microstructures; and a second cladding region formed as a layer around the first cladding region and made of a homogeneous material. A relative refractive-index difference ?1 between the core region and the second cladding region is equal to or higher than 0.01% and lower than 0.3%. A total cross-sectional area of the holes in the first cladding region with respect to a total cross-sectional area of the core region, the first cladding region, and the second cladding region is equal to or smaller than 20%. A waveguide is formed using the optical fiber.

Abstract: A plastic glass optical fiber includes a glass core (diameter a1, relative refractive index difference ?1, and refractive index n1), a polymer core (diameter a2, relative refractive index difference ?2, and refractive index n2), and a polymer cladding (refractive index n3), in which the diameter a1 of the glass core is within a range of 110 ?m to 200 ?m, a parameter X (X is a22/a12) is within a range of 1.15?X?2.9, a parameter Y (Y is ?2/?1) is within a range of 0.25?Y?0.84X?0.68 (when 1.15?X?2) or 0.48X?0.71?Y??(2/9)X+13/9 (when 2?X?2.9), a parameter ZR (ZR is Z2core/Z1core; Z2core=a22?/4×?(n12?n32) and Z1core=a12?/4×?(n12n?n22)) is within a range of 1.25?ZR?4.

Abstract: The invention relates to a composite structure (11) formed by a plurality of layers (13, 15, 17, 19, 21, 23) including an optical fiber (25) for structural monitoring purposes which is at least partly embedded in said structure (11), incorporating a protective cover (27) in those areas of its embedded part susceptible to needing repair, and to a process for repairing said embedded optical fiber comprising the following steps: identifying the optical fiber area in need of repair, removing material until reaching the cover (27), extracting said area, removing the protective cover (27), repairing the optical fiber (25), relocating the repaired area in the structure and returning the removed material.

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: A method for manufacturing a final optical fiber preform via overcladding of a primary preform having a cross section area is disclosed. The method includes at least one manufacturing step of the primary preform by deposit of an inner cladding and of a central core inside a tube of fluorine-doped silica, the tube being chosen such that it has a cross section area that is maximally about 15% less than the cross section area of the primary preform. With the method of the invention it is possible to manufacture a preform of large capacity at reduced cost which allows the drawing of an optical fiber having reduced transmission losses.

Abstract: An optical fiber, comprising: (i) a core having a core center and a radius or a width a, (ii) a cladding surrounding the core, and (iii) at least one stress member situated proximate to the fiber core within the cladding, said stress member comprising silica co-doped with F and at least one dopant selected from the list consisting of: GeO2, P2O5, Y2O3, TiO2 and Al2O3, wherein distance b between the stress member and the core center satisfies the following equation: 1?b/a<2.

Abstract: A catheter with many fiber optic pressure sensors. The sensor diaphragm is formed from a wafer with a thin silicon layer and a silicon substrate layer separated by a silicon dioxide layer. A method includes masking and etching channels through the silicon substrate layer in a pattern of concentric circles to form a concentric circular etched channels and cylindrical unetched portions of the silicon substrate layer between the channels, exposing the silicon dioxide in the etched regions, and dissolving the exposed silicon dioxide to expose the crystalline silicon layer in the etched regions. The unetched cylindrical portion of the silicon substrate forms the diaphragm support element and the thin silicon layer forms the diaphragm. After applying a reflective coating to the exposed thin silicon layer, the support element face is adhered to the end face of a tubular housing, and a fiber optic probe is inserted in the tubular housing.

Abstract: A narrow-linewidth micropulse LIDAR transmitter based on a low-SBS single clad, small-mode-area optical fiber. High narrow-linewidth peak powers are achieved through the use of an erbium doped fiber with an acoustic waveguide. Over 6 ?J per pulse (100 ns pulse width) is achieved before a weak form of stimulated Brillouin scattering appears. This laser has the potential to scale to very high power in a low-SBS dual clad fiber.

Abstract: An optical waveguide fiber comprising: (i) a Ge free core having an effective area of 90 ?m2 to 160 ?m2, at a 1550 nm wavelength, and ? value 12???25, said core comprising: (a) a central core region extending radially outwardly from a centerline to a radius r0?2 ?m, and having a relative refractive index percent profile ?0(r) wherein ?0.1% ??0(r) ?0.1%, and wherein the central core region has a maximum relative refractive index, ?0MAX, (b) a first annular core region surrounding and directly adjacent to the central core region and extending to an outer radius r1, wherein 4.8 ?m ?r1?10 ?m, and having a relative refractive index percent profile, ?1(r), and a minimum relative refractive index, ?2MIN, and the relative refractive index measured at a radius r=2.5 ?m being ?0.15??1(r=2.5 ?m) ?0, and ?0MAX ??1(r=2.

Abstract: The present invention relates to a method for amplifying the detected signal in a gas sensor. More specifically, the present invention relates to a method for increasing the concentration of the gas which is being detected in a sample or increasing the concentration of a gas which is directly obtained from the gas in the sample by chemical reaction. The gas which is to be detected is nitric oxide (NO). In particular, the method concerns the selective conversion of NO to NO2 which allows a threefold amplification of the number of analyte molecules in NO trace gas analysis in a single amplification cycle. Subsequent reduction or thermal decomposition of the obtained NO2 can provide NO again, which can again be introduced in a new amplification cycle. Multiple (n) amplification cycles can provide a sensitivity amplification by a factor 3n. The method can be combined with a multitude of detection methods and tolerates a high humidity.

Abstract: A rare earth-doped core optical fiber includes a core comprising a silica glass containing at least aluminum and ytterbium, a clad provided around the core and comprising a silica glass having a lower refraction index than that of the core, and a polymer layer provided on the outer circumference of the clad and having a lower refractive index than that of the clad, wherein aluminum and ytterbium are doped into the core such that a loss increase by photodarkening, TPD, satisfies the following inequality (A). By this rare earth-doped core optical fiber, it is possible to manufacture an optical fiber laser capable of maintaining a sufficient laser oscillation output even when used for a long period of time. TPD?10{?0.655*(DAl)?4.304*exp{?0.00343*(AYb)}+1.

Abstract: An optical fiber includes a core, an inner cladding and a low index ring of silica-based glass. The core comprises silica-based glass, an index of refraction n1, and a relative refractive index percent ?1% relative to pure silica glass. The inner cladding surrounds the core and comprises an index of refraction n2 and a relative refractive index percent ?2% relative to pure silica glass, wherein ?1%>?2% and the difference between ?1% and ?2% is greater than about 0.1%. The low index ring surrounds the inner cladding and comprises silica glass co-doped with boron and fluorine, a radial thickness of less than about 20 ?m, an index of refraction n3 and a third relative refractive index percent change ?3% relative to pure silica glass, wherein ?2%>?3% and ?3% is less than about ?1.0%.

Abstract: Optical waveguide fiber that is bend resistant and single mode at 1260 nm and at higher wavelengths. The optical fiber includes a core with a central core region and an annular core region or, alternatively, a high index core region and a low index core region. The optical fiber also includes a cladding with an annular ring region and an annular outer region.

Abstract: A method of fabricating an optical waveguide fiber that includes the steps of providing a cylindrical glass optical fiber preform having a longitudinally extending centerline hole, and closing the hole under conditions suitable to result in uniform and symmetric hole closure. The method may include first plugging a first end and a second end of the centerline hole to prevent gas flow therethrough. The method preferably involves closing the centerline hole of the preform by drawing the preform down into an optical waveguide fiber.

Abstract: An optical fiber comprising a flame retardant UV light-curable tight-buffer coating coated onto the fiber, wherein said tight-buffer coating is substantially halogen-free, and has a limiting oxygen index of at least about 22%, and wherein said tight-buffer coating is removable from said fiber with a strip-force of less than about 1800 grams when the fiber is upjacketed with said coating at a line speed of at least 300 m/min.

Abstract: Optical waveguide fiber that is bend resistant and single mode at 1260 nm and at higher wavelengths. The optical fiber includes a core of radius R1 and cladding, the cladding having an annular inner region of radius R2, an annular ring region, and an annular outer region. The annular ring region starts at R2, and the ratio R1/R2 is greater than 0.45.

Abstract: The invention concerns a method for making an optical fiber (18) including the following steps: producing a preform (10) containing nanoparticles provided with an active element including at least one recess (14) proximate at least part of the nanoparticles; fiber drawing of the preform (10) by introducing a non-oxidizing gas in the recess (14), thereby limiting the risks of oxidizing the nanoparticles of the preform (10). The preform (10) designed to the manufacture of an optical fiber (18) by the inventive method comprises nanoparticles provided with an active element in a doped zone (12) and at least one recess (14) proximate the doped zone (12).

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 pm 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: 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.