Abstract: The present invention relates to a method of manufacturing an optical fibre suitable for high transmission rates, which method comprises: i) supplying one or more glass forming precursors, and possibly a dopant, to a quartz substrate tube, ii) forming a plasma in the quartz substrate tube for the purpose of bringing about a reaction mixture so as to form glass layers, which may or may not be doped, on the interior of the substrate tube, iii) collapsing the substrate tube obtained in step ii) into a perform while heating, and iv) drawing an optical fibre from the perform while heating. The present invention furthermore relates to an optical fibre suitable for high transmission rates.

Abstract: An optical fiber preform comprises a central core portion having a maximal value Nc of refractive index in the center, and outside the central core portion, comprising at least a depressed portion having a minimal value Nd of refractive index, a ring portion having a maximal value Nr of refractive index and an outside cladding layer having a maximal value No of refractive index. The optical fiber preform satisfies a relation of Nc?Nr>No>Nd among the values of refractive index. A method of the optical fiber preform comprises fabricating a glass rod by inserting a rod containing at least the central core portion into a pipe containing at least the depressed portion and integrating them, fabricating a glass pipe having the ring portion, and fabricating a vitreous body by integrating the glass rod and the glass pipe by collapsing after inserting the glass rod into the glass pipe.

Abstract: Under condition that a non-circularity ratio is 5% or lower and a thermal expansion coefficient of a glass which forms the core is ?1 and a thermal expansion of a glass which forms the cladding is ?2, the difference of coefficients is controlled such that a formula ?2.5×10?7/° C.??1 ??2?1.0×10?7/° C. is satisfied so as to maintain a polarization mode dispersion to be 0.03 ps/km0.5 or lower. The difference of coefficients is further controlled such that a formula ?1.5×10?7/° C.??1??2?0/° C. is satisfied so as to maintain a polarization mode dispersion to be 0.015 ps/km0.5 or lower. By doing this, birefringence is reduced by adjusting the thermal expansion coefficient in a core and a cladding; thus providing an optical fiber, and an optical transmission path using the optical fiber, having preferable PMD for high speed transmission.

Abstract: The present invention discloses a core of an optical patch cord comprising a first end with a refraction index varying in a continuous manner along the radial direction, a second end including a blocking region at a radial center thereof, and a graded region extending from the first end to a predetermined position between the first end and the second end. The graded region has a refraction index distribution varying from the refraction index distribution of the first end to the refraction index distribution of the second end. The present optical signal transmission system comprises a multimode fiber and an optical patch cord including a first segment including a blocking region positioned at a radial center thereof and a second segment connected to the first segment for guiding a light beam into a region outside the blocking region of the first segment.

Abstract: The present invention relates to a method for preparing a GI (graded index) plastic optical fiber preform having a radial refractive index gradient, the refractive index increasing gradually from the outer periphery of the preform toward the center thereof, comprising inserting a 1st plastic tube (inside diameter: d1i, outside diameter: d1o) (111) made of a first polymer (refractive index: n1) in a cylinder reactor (inside diameter: d0i, d1o?d0i) and inserting a 2nd plastic tube (inside diameter: d2i, outside diameter d2o, d2o?d1i) (112) made of a second polymer (refractive index: n2, n2?n1) in the 1st plastic tube, the reactor, the 1st and 2nd plastic tubes are positioned coaxially, injecting a precursor of a third polymer (refractive index: n?, n??n2) into the 2nd plastic tube, injecting a precursor of a fourth polymer (refractive index: n?, n1?n??n2) into the space between the 1st and 2nd plastic tubes.

Abstract: A plastic optical fiber low in attenuation in a high order mode and small in mode dispersion, is presented. The plastic optical fiber comprises at least a core and a clad surrounding the core, characterized in that the core has a refractive index which gradually decreases from the core center towards the outside in the radial direction of the plastic optical fiber, and the refractive index of the clad is lower than the refractive index of the core center and higher than the refractive index of the core periphery.

Abstract: A gradient-index lens is structured by a multilayer film that includes therein a plurality of layers each of which has different refractive index and layer thickness from the other.

Abstract: The present invention relates to an optical fiber and the like comprising a structure enabling high-density packaging into an optical cable while making it possible to transmit signals with a high bit rate in both of wavelength bands of 1.3 ?m and 1.55 ?m. For example, this optical fiber is configured so as to have a mode field diameter of 8.0 ?m or less at a wavelength of 1.55 ?m, a cutoff wavelength of 1.26 ?m or less, and a chromatic dispersion with an absolute value of 12 ps/nm/km or less at wavelengths of 1.3 ?m and 1.55 ?m, thereby yielding an excellent lateral pressure resistance enabling high-density packaging into an optical cable.

Abstract: An optical waveguide fiber having large effective area, low slope, low cutoff, and low attenuation is disclosed. The optical fiber has at least two core segments and the inner profile volume of the core of the fiber is greater than 2.0%-?m2.

Abstract: A dispersion shifter fiber, which has zero dispersion wavelength on a long wavelength side beyond 1640 nm, a wavelength dispersion of ?1.0 to ?10.0 ps/nm/km at a wavelength range of 1530–1625 nm, a dispersion slope of less than 0.07 ps/nm2/km, a polarization mode dispersion of not more than 0.1 ps/(km)1/2 at a wavelength of 1550 nm, and a core cross-sectional area of 40–70 ?m2 at the wavelength of 1550 nm.

Abstract: A graded-index multimode fiber includes a core containing fluorine and a cladding which is provided at an outer periphery of the core, and the fiber has a refractive index profile which satisfies the following Formula (1): n ? ( r ) = { n 1 ? [ 1 - 2 ? ? ? ? ? ( r a ) ? ] 1 / 2 ( O ? r ? a ) n 1 ? ( 1 - 2 ? ? ? ) 1 / 2 ( r > a ) ( 1 ) where n(r) is a refractive index of the optical fiber at a distance “r” from the center of the core, n1 is a refractive index at the center of the core, ? is a relative refractive index difference of the center of the core with respect to the cladding, “a” is a core radius, and ? is a refractive index profile exponential parameter.

Abstract: A glass base material, which is a base material of an optical fiber, comprising: a core; and a clad surrounding the core; wherein: a rate of change in a relative-refractive-index-difference between the core and the clad in a longitudinal direction of the glass base material is substantially 6% or less.

Abstract: A half-dispersion-shifted single mode optical transmission fiber (HDSF) having a core and a cladding. The core has an inner core with a first refractive-index difference and a first glass layer surrounding the inner core and having a second refractive-index difference. The HDSF fiber has a peak refractive index difference of less than or equal to about 0.0140, a zero-dispersion wavelength greater than 1450 nm and lower than 1500 nm, a dispersion value of between about 6 and 11 ps/nm/km at an operating wavelength of about 1560 nm and an effective area of at least 60 ?m2. The cabled HDSF fiber has cutoff wavelength of less than about 1500 nm.

Abstract: An optical waveguide fiber including a central core region extending radially outward from the centerline and having a non-negative relative refractive index percent profile. The optical fiber exhibits an effective area of greater than about 60 ?m2 at a wavelength of about 1550 nm, a dispersion slope of less than 0.07 ps/nm2/km at a wavelength of about 1550 nm, and a zero-dispersion wavelength of less than about 1450 nm.

Abstract: The present invention relates to a dispersion compensation unit capable of compensating for both the chromatic dispersion and dispersion slope of a non-zero dispersion-shifted optical fiber. The dispersion compensation unit is formed by winding a first optical fiber and second optical fiber into coil shapes and storing them in a case. The first optical fiber has a negative chromatic dispersion D1 and a negative dispersion slope S1 at a wave length in use. The second optical fiber has a positive chromatic dispersion D2 and a positive dispersion slope S2 at the wavelength in use.

Abstract: An object of the present invention is to provide an optical fiber manufacturing method and an optical fiber in which an increase in the transmission loss is suppressed by preventing hydroxyl group from entering near the core portion. This invention provides a method for manufacturing an optical fiber 10 including forming a glass pipe 16 by applying a ring portion 15 on the inner face of a starting pipe 14 as a starting material, inserting a glass rod 13 that becomes a central core portion 11 and a depressed portion 12 into the inside of the glass pipe 16, integrating the glass pipe 16 and the glass rod 13 by collapse to form a glass body 17, forming a preform 10a by providing a jacket portion 18 outside the glass body 17, and drawing the preform 10a, wherein the thickness of the starting pipe 14 is set in a range from 4 mm to 8 mm.

Abstract: The invention relates to the field of amplifying or emitting optical fibers. It comprises an amplifying optical fiber doped with a rare earth comprising a plurality of successive segments (1, 2, 3, 4, 5), presenting a monomode core and a multimode core, presenting at the periphery of the multimode core a peripheral segment (4) of low index so as to increase the numerical aperture of the optical fiber, outer cladding (5) being situated at the periphery of the low index peripheral segment (4), the multimode core being at least in part above the outer cladding (5), the peripheral segment (2) presenting a decreasing gradient shape.

Abstract: A highly nonlinear optical fiber includes a core, a cladding surrounding the core, and a coating covering the cladding. A bending loss at a wavelength of 1550 nanometers with a bending diameter of 20 millimeters is equal to or less than 0.01 dB/m. A nonlinear coefficient at the wavelength of 1550 nanometers is equal to or more than 10 W?1km?1. A cut-off wavelength is equal to or less than 1530 nanometers. A zero dispersion wavelength is in a range between 1400 nanometers and 1650 nanometers. A diameter of the coating is 125 micrometers with a tolerance of ±5 percent.

Abstract: The invention relates to a multiband chromatic dispersion compensation optical fiber comprising successively, from the center toward the periphery, a central slice whose maximum index is higher than the index of the cladding, a buried slice whose minimum index is lower than the index of the cladding, and an annular slice whose maximum index is higher than the index of the cladding and lower than the maximum index of the central slice, a cladding of constant index, and having, on the one hand, at the wavelength of 1550 nm, firstly a chromatic dispersion of less than ?8 ps/nm.km, secondly a chromatic dispersion to dispersion slope ratio whose absolute value is greater than 750 nm, and thirdly a mode diameter greater than 5 ?m, and on the other hand, at the wavelength of 1625 nm, bending losses for a radius of 10 mm that are less than 400 dB/m.

Abstract: A dispersion compensating optical fiber for use in a high data rate telecommunications span or link. The dispersion compensating optical fiber in accordance with the invention provides excellent compensation of total dispersion over a range of wavelengths (e.g., 1527–1567 nm), thus minimizing signal distortion in wavelength division multiplexed systems. The dispersion compensating fiber has a refractive index profile with a central core segment having an inner peak with ?i%, an outer peak with ?1%, and a trough with a ?t% less than both ?i% and ?1%, a moat segment with a ?2%, and a ring segment with a ?3%. Preferably, ?t% and ?3% are greater than ?2%. Also disclosed is an optical transmission span having residual dispersion less than +/?25 ps/km for 100 km of transmission fiber over a wavelength band of 1527–1567 nm.

Abstract: Disclosed is a wide-band dispersion controlled optical fiber. The optical fiber enables the use of optical signals in various wavelength regions in a wavelength division multiplexing mode communication network by controlling the position of the zero dispersion wavelength, and enables long distance transmission by controlling dispersion slope and bending loss. Furthermore, there is an advantage in that the optical fiber enables not only short distance transmission but also middle/long distance transmission using a single type of optical fiber because the optical fiber is controlled to have negative dispersion values in the O-band wavelength region and positive dispersion values with small deviations in the C-band and L-band wavelength regions.

Abstract: An optical fiber (1?) having at least one Bragg grating (11), the fiber comprising a core (2) surrounded successively by cladding (3) and by a coating (4), the grating being obtained by being written directly in the core and/or the cladding of the fiber through the coating which is made of a material that is substantially transparent to ultraviolet type radiation used for writing the grating, and wherein the material of the coating contains a first polymer network interpenetrated by a second polymer.

Abstract: Disclosed is an optical fiber comprising a center core which forms a passageway for transmitting optical signals and has a refractive index N1, and a cladding which encloses the center core and has a refractive index N0. The optical fiber further comprises an upper core, which has a distribution of refractive indices increased starting from a refractive index N2 (>N0) at its outer circumference to the refractive index N1 at its internal circumference, and a minutely depressed refractive index region, which is interposed between said upper core and cladding and has a refractive index N3. The refractive index N3 is lower than the refractive index N0.

Abstract: A photonic crystal fiber comprising a bulk material having an arrangement of longitudinal holes, the fiber including a cladding region and a guiding core (280), the cladding region having an effective-refractive-index which varies across the fiber's cross section, wherein, in use, the effective-refractive-index variation causes light propagating in the fiber to have a different transverse profile from the profile that it would have if the cladding region were of a substantially uniform effective refractive index.

Abstract: An object of the present invention is to provide a method for manufacturing an optical fiber preform having a great diameter by reducing an eccentricity or a non-circularity of a core, an optical fiber preform having an small non-circularity and a complex refractive index profile, even with a great diameter, and an optical fiber that is applicable as a dispersion compensating fiber. The present invention involves a rod-in collapse process in which a glass rod is fixed within a glass pipe (or a dummy pipe attached to an end portion) via an aligning jig. The fixation via the aligning jig is made at one end or both ends, the aligning jig has a cylindrical shape with or without one or more reduced diameter portions. When fixed at one end, a heating and integrating process is preferably made from an opposite end. Employing the glass rod and the glass pipe having a refractive index distribution, a complex profile can be realized.

Abstract: An optical fiber comprises a core region extending along a predetermined axis X, and a cladding region surrounding the core region. The cladding region 14 comprises first to (N+1)-th regions such that the first region surrounds the core region, and the (k+1)-th region surrounds the k-th region (k=1, 2, . . . , N). At least one of the first to (N+1)-th regions includes, in a main medium having a predetermined refractive index, a sub-region made of an auxiliary medium having a refractive index different from that of the main medium. Letting n[0] be the average refractive index of the core region, and n[k] (k=1, 2, . . . , N+1) be the average refractive index of the k-th region, this optical fiber satisfies the relationship of n[0]>n[1], and n[i]>n[i+1] (?i=h, h+1, . . . , h+m; where h and m are natural numbers).

Abstract: A Dispersion Compensation (DC) fiber for low slope transmission fiber (such as a NZDSF) and transmission line including same. The DC fiber has a refractive index profile having a central core with a core delta (?1) value less than 1.8%, a moat surrounding the central core having a moat delta (?2) value greater than ?0.9%, and a ring surrounding the moat having a positive ring delta (?3). The DC fiber's refractive index profile is selected to provide total dispersion less than ?40 and greater than ?87 ps/nm/km, and kappa of greater than 165 and less than 270 nm, all at 1550 nm. The DC fiber, when used in a transmission line, may provide low average residual dispersion across the C, L, and C+L when such lines include transmission fibers with a total dispersion between 4 and 10 ps/nm/km and a dispersion slope less than 0.045 ps/nm2/km at 1550 nm.

Abstract: A multi-lens apparatus for altering the mode field of an optical signal is disclosed. The apparatus includes an optical fiber having a core region defining an optical axis and a GRIN-fiber lens positioned in relation to one end of the optical fiber. A biconic lens including an external surface defined by two different curves disposed substantially orthogonal to one another, a major curve C1 and a minor curve C2, with C1 and C2 intersecting at or near the optical axis is positioned in relation to an end of the GRIN-fiber lens remote from the fiber. A method of manufacturing a multi-lens apparatus for altering the mode field of an optical signal, and an optical assembly are also disclosed.

Abstract: The optical fiber has a dispersion value at a 1.55 ?m-wavelength band, of 6 to 24 ps/nm/km, and satisfies A>3×D+40, where D represents a dispersion value (ps/nm/km) at a central wavelength of a 1.55 ?m-wavelength band, and A represents an effective core area (?m2). The optical transmission line for transmitting an optical signal, which includes the optical fiber is provided as well.

Abstract: A wide band dispersion-controlled fiber which comprises a core forming an optical signal transmission path and having a peak refractive index, and a cladding surrounding the core and having a peak refractive index lower than the peak refractive index of the core. The wide band dispersion-controlled fiber further comprises at least one dispersion control layer arranged between the core and the cladding and having a refractive index profile such that its refractive index increases from an inner periphery to an outer periphery. The minimum refractive index of the dispersion control layer is less than the peak refractive indices of the core and cladding.

Abstract: The specification describes an improved optical fiber design in which the criteria for high performance in a Raman amplified optical system, such as moderate effective area, moderate dispersion, low dispersion slope, and selected zero dispersion wavelength, are simultaneously optimized. In preferred embodiments of the invention, the dispersion characteristics are deliberately made selectively dependent on the core radius. This allows manufacturing variability in the dispersion properties, introduced in the core-making process, to be mitigated during subsequent processing steps.

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/?{square root over (k)}m at a wavelength of 1550 nm and a loss increase of no more than 40 dB/m in a bending diameter of 20 mm.

Abstract: The invention relates to a low dispersion slope dispersion-shifted single-mode fiber for large capacity transmission comprising a core and a cladding. Said fiber is characterized in that said core has three to five core segments having different refractive index profiles, and said cladding has four to six cladding segments. The total dispersion slope of said fiber at 1550 nm is less than 0.060 ps/nm2·km, the zero dispersion wavelength is less than 1420 nm, the effective area ranges from 55 ?m2 to 65 ?m2, and the dispersion in the region of 1530 nm˜1565 nm ranges from 5.0 ps/nm2·km to 12.0 ps/nm2·km. The fiber has low dispersion slope, moderate dispersion, low attenuation, and excellent bend resistance performance. It is suitable for a high-speed (10 Gbits/s and 40 Gbits/s), large capacity, and long distance DWDM system.

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 waveguide, such as an optical fiber, including a core having a refractive index nco and a radius rco; an inner cladding laterally surrounding the core, the inner cladding having a refractive index nic and an outer radius of ric; an outer cladding laterally surrounding the inner cladding, the outer cladding having a refractive index noc; and a narrow depressed well, wherein nco>noc>nic. The range of the ratio of the inner, depressed-well clad radius, ric, to core radius, rco, varies from about 2.4 to 3.0. The waveguide has a +? of about 0.0014 to 0.0021, a ?? of about ?0.0021 to ?0.0034, and a ?Tot of about 0.0043 to 0.0049.

Abstract: Optical waveguide fiber having low water peak as well as optical waveguide fiber preforms and methods of making optical waveguide fiber preforms from which low water peak and/or low hydrogen aged attenuation optical waveguide fibers are formed, including optical waveguide fiber and preforms made via OVD. The fibers may be hydrogen resistant, i.e. exhibit low hydrogen aged attenuation. A low water peak, hydrogen resistant optical waveguide fiber is disclosed which exhibits an optical attenuation at a wavelength of about 1383 nm which is less than or equal to an optical attenuation exhibited at a wavelength of about 1310 nm.

Abstract: A dispersion compensating fiber, which has a negative dispersion slope with a large absolute value while maintaining the absolute value of the chromatic dispersion, and which has sufficient dispersion slope compensation properties even for the non-zero dispersion shifted optical fiber requiring a large RDS for dispersion compensation. In this dispersion compensating fiber, the radius of a ring core region is set in a range from 6.7 ?m to 10.7 ?m, the radius ratio of a depressed core region relative to a central core region is set in a range from 2.0 to 3.0, and the radius ratio of the ring core region relative to the depressed core region is set in a range from 1.3 to 2.0, the relative refractive index difference of the central core region relative to the cladding is set in a range from +1.00% to +1.80%, the relative refractive index difference of the depressed core region relative to the cladding is set in a range from ?1.20% to ?1.

Abstract: An optical fiber transmission line including first, second and third optical fibers connected together so that light travels through the transmission line from the first optical fiber, then through the second optical fiber and then through the third optical fiber. The first, second and third optical fibers have first, second and third characteristic values, respectively. The second characteristic value is larger than the first characteristic value and the third characteristic value. The characteristic value of a respective optical fiber being a nonlinear refractive index of the optical fiber divided by an effective cross section of the optical fiber. Pump light is supplied to the transmission line so that Raman amplification occurs in the transmission line as an optical signal travels through the transmission line.

Abstract: The field of the invention is that of chromatic dispersion compensation modules and of methods of designing chromatic dispersion compensation modules. The design method includes an optimization step consisting in reducing an original quality criterion. The compensation optical fiber of the module has a chromatic dispersion less than a first threshold and chromatic dispersion sufficiently negative for the quality criterion to be less than a second threshold.

Abstract: Disclosed is a mode-filtering and mode-selecting method in a multi-mode waveguide, and a waveguide amplifier, a semiconductor laser, and a VCSEL using the method. These optical elements include a cladding region that has a periodically changed refractive-index structure, thereby obtaining a mode-filtering or mode-selecting function, which in turn allows only a single mode in the transverse direction to propagate along the waveguide. By forming the periodic index-variation structure, the EDF, the semiconductor laser, and the VCSEL achieve a single mode operation although the cross-sectional area is much larger than that of the prior art, consequently realizing a high-performance or high-power single-mode amplifier and laser.

Abstract: Disclosed is a method of making a photonic crystal optical fiber preform by stacking and bonding individual glass disks. In one embodiment, each glass disk has a pattern of voids formed therethrough, and the pattern for each disk is the same. In another embodiment, glass blanks are formed without voids and stacked with disks having voids wherein an optical fiber preform is formed having channels closed at both ends by glass having no channels. Also disclosed is an optical fiber having channels closed at both ends by glass without channels.

Abstract: A dispersion compensating optical fiber that includes a segmented core having a central core segment, a moat segment, and a ring segment wherein the ring segment is preferably offset from the moat outer radius, r2, by a ring offset, Xo, greater than 0.4 ?m. The refractive index profile is selected to provide a total dispersion at 1550 nm of between about ?120 and ?145 ps/nm/km, and a total dispersion slope at 1550 nm of between about ?0.36 and ?0.56 ps/nm2/km. The refractive index profile is preferably further selected to provide a kappa, defined as the total dispersion at 1550 nm divided by the dispersion slope at 1550 nm, of between about 250 and 320 nm. Optical transmission systems including the present invention dispersion compensating optical fiber which have residual dispersion less than +/?15 ps/nm per 100 km of standard single mode transmission fiber are also disclosed.

Abstract: An optical transmission fiber has a refractive index profile with an area of increased index of refraction at the inner core of the fiber, an annular region positioned radially outward from the inner core with an index of refraction exceeding the index of the inner core, and at least a low dopant content region in a cross-sectional region between the inner core and the annular region. A low loss cladding layer surrounds the core region. The optical transmission fiber with this segmented core profile provides a high effective area, low non-linearity coefficient, nonzero dispersion, and relatively flat dispersion slope.

Abstract: An optical module comprises a multiplexer for combining a signal and a pump radiation and having an output coupled to an optical fiber and a signal over the optical fiber with the pump lightwave that has a frequency three times of that of the signal and phase index equal to that of the signal. Phase matching between the pump and signal is realized for example by employing a microstructured optical fiber as the optical fiber.

Abstract: Disclosed is an optical waveguide fiber having a reduced PMD and a method of making the optical waveguide fiber. The optical waveguide fiber in accord with the invention has a particular spin pattern impressed upon the optical waveguide fiber during the drawing step. The spin pattern causes the fast axis of birefringence to rotate along the long axis of the optical waveguide fiber. The spin functions in accord with the invention provide for reduced PMD even in cases in which draw speed, spin magnitude, or modulation parameter vary while the spin pattern is being impressed upon the optical waveguide fiber.

Abstract: A microstructured optical fiber is structured with a core region and a plurality of cladding regions surrounding the core region. Chromatic dispersion is relatively flat over a broad wavelength range with a small effective area, without need for air holes that are unacceptably small. An enlarged effective core area is obtained by selectively closing the holes in the innermost cladding, which holes are smaller and easier to close than the holes in other regions.

Abstract: Two lenses are used for forming a collimator parallel pair, in which the distance between the two lenses is substantially made coincident with the maximum distance allowing beam waists to be formed at equal distances from the two lenses respectively.

Abstract: The present invention provides an optical fiber suitable for the manufacture of optical fiber couplers and having low macrobending loss, low cutoff wavelength, low attenuation, and low sensitivity to variations in overclad mass. One aspect of the present invention provides an optical fiber having a core having an index profile, the index profile of the core having a value of ? of between about 1.7 and about 3.0; and a cladding region surrounding and in contact with the core, the cladding region having an outer radius of at least about 40 ?m, wherein the optical fiber has a cutoff wavelength of between about 870 nm and about 970 nm, and a macrobending loss of below about 1 dB at a wavelength of 1550 nm when wrapped one turn around a 32 mm mandrel.

Abstract: The specification describes an improved optical fiber design in which the criteria for high performance in a Raman amplified optical system, such as moderate effective area, moderate dispersion, low dispersion slope, and selected zero dispersion wavelength, are simultaneously optimized. In preferred embodiments of the invention, the dispersion characteristics are deliberately made selectively dependent on the core radius. This allows manufacturing variability in the dispersion properties, introduced in the core-making process, to be mitigated during subsequent processing steps.

Abstract: Disclosed is a single made optical waveguide fiber having a segmented core design. In particular, the core comprises three segments, each having characteristic dimensions and refractive index profile. By proper choice of index profile in each segment, a waveguide fiber is made which has a mode field diameter of about 9.5, low, positive total dispersion over the operating window 1530 nm to 1565 nm as well as effective area greater than 60 ?m2.