KR100443213B1 - Dispersion-compensating single mode optical waveguide fiber, method of making same, and dispersion compensating single mode optical waveguide fiber link - Google Patents

Abstract

The dispersion compensating single mode optical waveguide fiber is designed to change the operating wavelength window of the link from 1310 nm to 1550 nm. The dispersion compensating waveguide fiber is characterized by a core glass region refractive index profile comprising at least three segments. The segment on the waveguide center has a positive refractive index. At least one segment away from the waveguide centerline has a negative relative refractive index.

Description

Dispersion-compensating single mode optical waveguide fiber, method of making same, and dispersion compensating single mode optical waveguide fiber link

BACKGROUND OF THE INVENTION

The present invention relates to single mode optical waveguide fibers tuned to a negative overall dispersion and a relatively large effective area. In particular, the single mode waveguide has a total dispersion of less than -100 ps / nm-km.

Several factors are combined to produce the most desirable wavelength range of 1500 nm to 1600 nm for telecommunication systems using optical waveguide fibers. these are

A reliable laser available for a wavelengh window of about 1550 nm;

An optical fiber amplifier of the present invention having an optimum gain curve in a wavelength range of 1530 nm to 1570 nm;

A usable system capable of wavelength-dispersive multiplexing of signals in such a wavelength range; And

And is a usable waveguide fiber with low dispersion to achieve very low attenuation over this wavelength range.

This advancement in technology makes possible a multi-channel telecommunication system with very high information rate, which is far between stations where the signals are electrically generated.

However, many telecommunication system installations are preceded by technological advances to make 1550 nm the most desirable operating window. These early systems were designed primarily for use in wavelength ranges around 1310 nm. The design includes a laser operating at a wavelength around 1310 nm and an optical waveguide having a zero dispersion wavelength around 1310 nm. In this system, the optical waveguide fiber has a local minimum attenuation around 1310 nm, but at 1550 nm it is about half the minimum at 1310 nm, the theoretical minimum.

Methods have been explored for using these older systems for new laser, amplifier, and multiplexing technologies. An essential characteristic of the method is that it compensates for the overall dispersion of the link at 1550 nm, as described in another patent, which is set forth and described in US Pat. No. 5,361,319 ("319 Antos") by Antos et al. A single length of waveguide fiber is inserted into each waveguide fiber link to overcome a relatively high total dispersion. As used herein, the term " link " refers to the length of a waveguide fiber that measures the distance between a signal source, a transmitter or an electrical signal generator, and a receiver or another electrical signal generator Is defined.

The '139 Antos patent relates to a dispersion compensating waveguide fiber having a core refractive index profile that provides dispersion at about 1550 nm to -20 ps / nm-km. The conventional distributed signal rule in the prior art is that if the shorter wavelength light has a higher velocity in the waveguide, the dispersion of the waveguide is a positive value. Since the dispersion of the waveguide fiber at about 1550 nm with a dispersion wavelength of about zero at about 1310 nm is about 15 ps / nm-km, the length of the dispersion compensating waveguide fiber required to completely compensate for total dispersion at 1550 nm is Of the link length of 0.75. Thus, for example, a 50 km link of waveguide fiber has a total dispersion of 750 ps / nm since it is 15 ps / nm-km x 50 km at 1550 nm. In order to efficiently remove such dispersion, the length of the dispersion compensating waveguide fiber is required to be 32.5 km at 750 ps / nm ÷ 20 ps / nm-km.

The additional attenuation injected into the link by the dispersion compensation waveguide must be canceled by the optical amplifier. The injection of an additional electric generator into the link is not cost effective. In addition, the cost of the dispersion compensating waveguide fiber accounts for a significant portion of the total waveguide fiber cost. The long length of the required dispersion compensating waveguide should be formed into an environmentally stable package capable of taking up considerable space.

Generally, the compensating waveguide fiber design has many refractive index modifying dopants in the core region, so the attenuation is higher at the link than at the standard waveguide fiber.

The higher signal intensity levels that can be formed by optical amplifiers and advanced lasers as well as wavelength division multiplexing increase the likelihood that the length of the link or data transmission is limited by nonlinear optical effects. The effect of this non-linear effect can be limited by increasing the effective area of the fibers (A _eff ). The effective area is Aeff = 2 π (E2rdr) 2 / (E4rdr), where the integral limit is from 0 to ∞, and E is the electric field related to the propagation light. Distortion (distortion) due to the non-linearity is dependent on the Ptn2 / Aeff, where P is the signal intensity, n ₂ is the nonlinear refractive index constant. Therefore, it should be noted that in the design of the dispersion compensating waveguide fiber, the A _eff of the compensating fiber must be large enough so that the compensating fiber does not cause a significant non-linear effect on the link. If the _Aeff of the compensating fiber is less than the area of the original fiber at the link, the compensating fiber will be located at the link position where the signal strength is lower and the nonlinear effect is minimized. Also, the less A _eff of the compensating fiber in many links occupies a small fraction of the total link length and does not have a significant effect on the nonlinear distortion of the signal.

Thus, the attenuation is sufficiently low to have a length that is less than 15% of the link length, for example, eliminating the need for additional signal amplification to offset compensating waveguide fiber attenuation;

Compensating optical waveguide fibers having an effective area large enough to exclude the non-linear dispersion effect in the compensating waveguide fiber from the limited factor are needed.

Justice

- Effective area is Aeff = 2 π (E2rdr) 2 / (E4rdr), where the integral limit is from 0 to ∞ and E is the electric field related to the propagation light.

- a non-linear discriminator factor is Gnl = n2 / Aeff (exp [ D1tL1 / Dd / a] -1) / a, where n ₂ is the nonlinear refractive index, D ₁ is the variance of the waveguide section optimized at about 1310nm, L ₁ Is the length corresponding to D ₁ , D _d is the dispersion of the compensating waveguide fiber, and? Is the attenuation of the dispersion compensating fiber. The expression G _nl is derived from the basic definitions Gn 1 to Gn 2 / Aeff (effective length x output intensity). The effective length and output are expressed by the equation of waveguide fiber length and attenuation α. The compensating waveguide fiber is substituted into the equation according to D1tL1 = DdtLd requirements. Since G _nl is a combination of system parameters such as system structure, amplifier spacing, Dd / a and n2 / Aeff, it has properties useful for increasing the efficiency of the link.

[Summary of the Invention]

The present invention relates to an improved dispersion compensation waveguide fiber. It has been found that a kind of segmented core refractive index profile introduced in US Pat. No. 4,715,679 to Bhagavatula and US patent application Ser. No. 08 / 378,780 to Liu is the only suitable for dispersion compensating waveguide fibers.

It is a first object of the present invention to provide a single mode optical waveguide fiber having a core glass region and a clad glass which is a peripheral layer. The core glass region has at least three segments, which are each characterized by a refractive index profile, a radius r, and a%. Definition of the refractive index difference Δ% is the% u = [(n12-nc2 ) / 2n12] t100, n 1 is the core refractive index and, n _c is the clad refractive index. In other words, n ₁ is the maximum refractive index in the core region characterized by% Δ. The radius of each segment measures from the centerline of the waveguide fiber to the point of the segment furthest away from the centerline. The refractive index profile of a segment is given as a refractive index value at the point of the radius of the segment. For the first purpose of the invention, Δ ₁ % of the _first segment is a positive value and Δ% of at least one other segment is negative. The radius and Δ% of the segment at 1550 nm are chosen to provide a negative overall dispersion value of -150 ps / nm-km or less.

In an embodiment for the first purpose, the core glass region has three segments and the second segment has a negative?%. A preferred embodiment proceeds outward from the first segment to provide an effective area A _{eff of} at least about 30 탆 ² at 1550 nm, and has a radius in the range of about 1 to 1.5 탆, 5.5 to 6.5 탆, and 8 to 9.5 탆 And each segment having a Δ% in the range of about 1.5 to 2%, -0.2 to -0.5, and 0.2 to 0.5. An effective area larger than 60 mu m < ² > can be achieved.

In another embodiment of the first object, the core glass region has four segments, the second and fourth segments having a negative Δ%. Preferred embodiments each have a radius in the range of about 1 to 2 占 퐉, 6 to 8 占 퐉, 9 to 11 占 퐉, and 13 to 17 占 퐉, which extend outward from the center of the waveguide. The Δ% of the corresponding segment has a range of about 1 to 2%, -0.2 to -0.8%, 0.4 to 0.6% and -0.2 to -0.8%, respectively. These preferred core profiles provide an A _{eff of} at least 30 μm ² at 1550 nm. The dispersion slope of 2 to 15 ps / nm-km provided by this core profile is reasonably small.

In another embodiment for this purpose of the invention, the core glass region has four segments, numbered from 1 to 4 starting at the center of the waveguide fiber. The relative refractive index% of the segments is in order of Δ ₁ %> Δ ₃ %> Δ ₄ %> Δ ₂ %, where Δ ₂ % is a negative value. Each Δ is 1.5% to 2%, -0.2 to -1.45% in the Δ _2%, 0.25 to 0.45% in the Δ _3%, 0.05% to 0.25% in the Δ _4% according to Δ _1%, and this Δ each radius is related to the% 7 to 8㎛, and r ₄ to 9 according to 12㎛ in the 4.5 to 5.5㎛, r ₃ in about 0.75 to 1.5㎛, r ₂ according to r _1. In this embodiment, the overall dispersion slope is negative, provided to eliminate the positive slope of the waveguide fibers of the original link operating in a 1310 nm window. Typically, the slope of the total dispersion is negative in the range of about -0.1 to -5.0 ps / nm ² -km.

A second object of the present invention is to provide a single mode optical waveguide fiber link fabricated with a first length of single mode fiber and a length of dispersion compensating single mode waveguide fiber designed to operate in a 1310 nm window. The dispersion compensating fiber length and total dispersion product at 1550 nm are chosen to be mathematically added to the length x dispersion of the first length of the waveguide fiber to represent the preselected value of the total dispersion in the link. The preselected value is preferably selected to be 0 at 1550 nm to provide the lowest overall dispersion over this window. If four wave mixing or self-phase modulation is a probable problem in a 1550 nm window operation, the total dispersion at 1550 nm will be chosen to be a small positive number.

The attenuation of the dispersion compensation waveguide fiber is fixed at a low value because the attenuation in the link does not become a limiter of the data rate. In addition, A _eff should be at least about 30 μm ² , since a significant nonlinear dispersion effect is not injected by the dispersion compensation waveguide fibers. With A _eff , the ratio of the total dispersion and attenuation of the compensating fiber is combined with a function which appears in the prior art and as described above with the identification factor denoted G _nl , which is a measure of the properties of the compensating waveguide fiber for the nonlinear dispersion effect .

The above-described embodiment of the present invention includes dispersion compensating waveguide fibers having a total dispersion D _d of -150 ps / nm-km or less, A _eff ≥ ³⁰ μm ² , and a magnification D _d / α≥250 ps / nm-dB.

Since the total dispersion of the compensating fiber has a large negative number, the length of the compensating fiber required to reach a preselected value of the total dispersion in the link is generally less than 15% of the link length, Less than 5%.

A third object of the present invention is to provide a method of manufacturing a single mode optical waveguide that compensates dispersion at 1550 nm on a link designed primarily for operation in a 1310 nm window. A drawn preform comprising a central core glass region and a peripheral clad glass layer will be produced by several conventional techniques, wherein said core glass region has the above-described characteristics as described for the first purpose of the present invention. These include, in the prior art, internal and external chemical vapor deposition, condensation vapor deposition and variations of these techniques. The core region having a positive relative refractive index can be produced using a dopant such as germania in a silica glass matrix. The core region having a negative refractive index will be fabricated using a dopant such as fluorine.

It has been found that a drawing tension of greater than about 100 grams results in a better overall dispersion versus damping ratio than similar waveguide fibers drawn at lower stresses. In order to limit losses due to bending, an outer diameter of greater than about 125 [mu] m is preferred. The upper limit at the outer diameter is set by practical limitations such as cost and size of the cable required. The practical upper limit is about 170 mu m.

To limit attenuation by residual coating stress, the coated waveguide fibers will loosely wrap and be heat treated on a spool. For the most effective stress reduction, the size of the spool should be greater than about 45 cm. The winding tension used to wrap the waveguide fibers on the spool is less than about 20 grams. A preferred winding method is to allow the waveguide fibers to assume only a chain-like structure before being wound on the spool.

It has been known that heat treatment that lasts from 1 to 10 hours at a temperature of at least 30 캜, which is higher than the glass transition temperature Tg of the polymer coating, is effective to reduce the residual coating stress for the type and thickness of the coating used for testing. A fixing time of about 5 hours is effective at a thickness of about 60 占 퐉 of the UV cured acrylate coating used for producing the waveguide fiber described in the present invention.

It will be appreciated that the heat treatment method cited herein includes limits of temperature and time suitable for the type and thickness of some suitable polymer coatings used to make the optical waveguide fibers.

Figure 1 is a general graph of the novel core region refractive index profile,

Figure 2 is a specific implementation of the novel core region refractive index profile,

Figure 3 is a view of a particular shape formed on a drawing preform consistent with the implementation of a novel core profile,

4A shows a curve of the relationship between the ratio of total dispersion and attenuation and the discriminator factor,

Figure 4B shows the dependence of the system loss injected by the compensating waveguide fibers in the ratio of total dispersion and attenuation.

The wide application of the design of the segmented core waveguide fibers as a specific telecommunications system requirement is caused by the flexibility provided by the segmented core concept. The number of core segments is limited only by the core diameter and the narrowest core segment that can affect the propagation of light in the waveguide. Also, for example, the width, position, refractive index profile and relative position of core segments at the long axis centerline of the waveguide affect the properties of the segmented core waveguide fibers. The large number of substitutions and bonds in the sig- nals causes flexibility in the partitioned core design.

The problem solved by the present invention, which will be described and illustrated, is to upgrade a telecommunication system designed to operate in a 1310nm window and operate without relying on a significant overhaul of the system at 1550nm wavelength window. The solution to this problem is dispersion compensating waveguide fibers that have total dispersion characteristics, attenuation and A _eff to allow transmission at high data rates in a 1550 nm working window, which can already be inserted into the communication link. In particular, the compensation fiber should have a dispersion characteristic that essentially eliminates the 1550 nm window dispersion of the 1310 nm section of the link. The compensating fiber should have a low attenuation which makes it possible to fully insert the compensating fiber into the link which is not required at signal generation. In this case, optical amplification of the signal will be required. The _Aeff of the compensating fiber should be sufficiently large such that the compensating fiber does not become a data rate limiting element with respect to nonlinear effects.

A typical core domain refractive index profile that meets these requirements is shown in FIG. In the embodiment of the present invention, the refractive index of the segment 8 is such that the core glass region has three segments, (10). The invention is not limited to three or four segment core refractive index profiles. However, in terms of manufacturing cost, the simplest profile satisfying the requirements of the system is desirable.

Dashed line 7 shows the deformation that can be formed in the sigmoidal refractive index profile without substantially changing the characteristics of the waveguide fiber. The corner of the profile is rounded. For example, the shape of the central profile may be triangular or parabolic. The requirement of one segment is to have a negative Δ%. Another statement of the effect of the deformation or the perturbation of the low profile is Δ%, and the width at the base and the outer radius of the segments are more important factors in determining the waveguide fiber properties.

Table 1 below shows a computer model study conducted to increase the sensitivity and sensitivity of the waveguide fibers to the position and Δ% of core seg- ments. The refractive index profiles 1 to 5 represent the four segment core region refractive index profiles of FIG. The refractive index profile 6 is a third segment having all the characteristics of FIG. 1 except for the last segment 8.

Refractive index 1 Refractive index 2 Refractive index 3 Refractive index 4 Refractive index 5 Refractive index 6 Dispersion degree ps / nm-km -430 -549 -475 -220 -310 -327 Dispersion slope ps / nm ^2- km 6.3 9.8 10.6 2.4 13.6 4.2 A _eff ㎛ ² 78 104 132 58 208 72 Cutting ㎛ 2.2 2.3 1.9 2.0 1.9 1.9 Δ ₁ % 1.5 1.5 1.45 1.5 1.5 2.0 r ₁ μm 1.5 1.5 1.5 1.5 1.45 1.05 Δ ₂ % -0.5 -0.5 -0.5 -0.5 -0.5 -0.3 r ₂ ㎛ 6.5 7 8 5.8 8 6 Δ ₃ % 0.5 0.5 0.5 0.6 0.6 0.35 r ₃ μm 10.5 11 11 9 11 8.8 Δ ₄ % -0.5 -0.5 -0.5 -0.5 -0.5 0 r ₄ ㎛ 13 13 17 13 17 -

Some desirable characteristics of this design are shown in Table 1 above.

- Very large negative dispersion can be obtained with large A _eff for all studied refractive index profiles;

- Cutting wavelengths are relatively insensitive to changes in segment parameters;

The third segment core can satisfy the requirements of many system architectures.

Also, if the system requires a lesser amount of negative total dispersion, a reduced total dispersion slope can be achieved.

Refractive index 21 Refractive index 22 Refractive index 23 Dispersion degree ps / nm-km -310 -280 -273 Dispersion slope ps / nm ^2- km -0.1 -2.4 -1.2 A _eff ㎛ ² 25 19 22 Cutting ㎛ 2.0 1.9 1.9 Δ ₁ % 2.0 2.0 2.0 r ₁ μm 1.1 1.1 1.1 Δ ₂ % -0.3 -0.3 -0.3 r ₂ ㎛ 5.5 6 5.5 Δ ₃ % 0.35 0.35 0.35 r ₃ μm 8 8.8 8.3 Δ ₄ % 0.1 0 0 r ₄ ㎛ 10 - -

An embodiment of the novel profile shown in Figure 2 represents four segments 12, 14, 16 and 18 core glass regions. The clad glass layer is shown as a structure 20. The main characteristics of this design are

Relative to the central segment-relative index of refraction portion 14 is higher than the design of Figure 1,

There is only one negative relative refractive index portion 14,

The radius of the segments 14, 16 and 18 is reduced compared to the design shown in Fig. One effect of moving the position of the segment closely to the waveguide centerline is that A _eff is reduced.

The design of the core glass region refractive index profile 21 is as shown in FIG. The refractive index profiles 22 and 23 are similar to those shown in Figure 2 except that the% of the segment 18 is zero in this case. Table 2 above shows the results of a computer model study to increase the properties of the core domain refractive index profile that forms a negative overall dispersion slope on the dispersion compensating waveguide fibers. The negative total dispersion slope of the compensating waveguide fiber is provided to eliminate at least a portion of the positive slope of the remainder of the link to lower the link dispersion slope over the wavelength of 1550 nm of operation. The data in Table 2 indicate that A _eff is low when the dispersion slope is negative. Thus, this compensation waveguide design is used in the portion of the link where the short length of the compensating fiber is required, or where the nonlinear dispersion effect is not important, i.e. the signal power density is low.

Example - A third segment profile with large Dd / a

The optical waveguide fiber preform was prepared to have a third segment core glass region refractive index profile shown in Fig. The center segment 22 had a Δ% of 1.83. Segment 24 had a negative?% Of -0.32%. Segment 26 had a relative refractive index of 0.32%. The radius of the segment is in mm from the abscissa and is converted to their waveguide fiber equivalent using an outer diameter of the last waveguide fiber of 155 μm. The average drawing stress is about 200 gm. The resulting waveguide fibers are loosely wound on a 46 mm diameter spool and heated at 50 DEG C for about 10 hours.

The total dispersion was -214 ps / nm-km and attenuation was 0.6 dB / km, resulting in a Dd / a of 356 ps / nm-dB. The effective area was 50 탆 ² . Preferably, in the waveguide having the core structure, the dispersion slope is in the range of -2 to +2 ps / nm ² -km.

The non-linear discriminant factor of G _n1 is shown in comparison with D d / a in FIG. 4A. The result of curve 32 makes it easier to achieve the expected system performance given a non-Dd / a. This, the value of G _nl Less according to the value of Dd / a becomes large, as mentioned in the above equation G _nl been found. Thus, the waveguide fiber performance from the system viewpoint can be estimated from the Dd / a ratio. In addition, the trade-off of dispersion for attenuation in the dispersion compensating fiber can be read from the chart of FIG. 4A. For example, if a particular system can only operate when G _n1 is less than about 30, then the dispersion of the compensating fiber is in the range of -150 to -400 ps / nm-2, as attenuation varies between 0.29 dB / km and 3.2 dB / km. < / RTI >

The chart shown in Figure 4B may also be used to improve the performance of the dispersion compensating waveguide fiber. The y-axis is the total loss injected into the link by the dispersion compensating waveguide fiber. The x-axis is the Dd / a ratio. Curve 34 was drawn assuming that the base system designed for 1310 nm window operation has a length of 100 km and a dispersion of 17 ps / nm-km at 1550 nm. The improvement in losses caused as Dd / a increases is expressed as the value of this ratio, which estimates the performance of the dispersion compensating waveguide fiber.

Although specific embodiments of the invention have been described above, the invention is not limited thereto.

Claims (19)

Wherein the first segment is positioned to include a waveguide centerline and is located at a distance from the centerline to the first line of the first line, Further segments adjoining each other having a radius r ₁ extending to a segment of the first segment and having a relative refractive index of% ₁ % extend radially outward from the first segment, Having a radius r _i extending to a point of an i-th segment located far away, i = 2 to n, and having a relative refractive index% _i when n is the number of said segments, The first segment having a positive value < RTI ID = 0.0 > ₁ % < / RTI > and being symmetrically positioned with respect to the long axis of the optical waveguide fiber, and A core glass region comprising at least one segment having a negative value? _I %; And And a clad glass layer surrounding the core glass region having a refractive index n _c that is less than the refractive index of at least a portion of the core glass region, Wherein the respective ratios r ₁ and r _i , the relative refractive indices% Δ ₁ % and Δ _i % are selected to provide a pre-selected total dispersion of at least about-150 ps / nm / km at 1550 nm, . The single mode optical waveguide fiber of claim 1, wherein the core glass region comprises three segments and the second segment has a negative Δ%. According to claim 2, wherein each signature garment is to provide ^two or more 30㎛ effective area A _eff at 1550nm, starting from the signature of the first garment facing outward, one to 1.5㎛, 5.5 to 6.5㎛, And a radius in the range of 8 to 9.5 [mu] m; Starting from the first segment and having a Δ% in the range of from 1.5 to 2%, from -0.2 to -0.5%, and from 0.2 to 0.5%. The single mode optical waveguide fiber of claim 1, wherein the core glass region has four segments and the second and fourth segments of the core glass region each have a negative Δ%. The method of claim 4, wherein each of the signature treatments to provide at 1550nm 30㎛ ² or more the effective area A _eff, starting from the signature of the first garment facing outward, one to 2㎛, 6 to 8㎛, 9-11 [mu] m and 13-17 [mu] m; And has a Δ% ranging from 1 to 2%, from -0.2 to -0.8%, from 0.4 to 0.6% and from -0.2 to -0.8%, starting from the first segment. fiber. Claim 5 wherein, a single mode optical waveguide fiber, characterized in that the total dispersion slope in the range of about -2 to 15 ps / nm ² -km to. 2. The method of claim 1, wherein the core glass region has four segments starting from 1 in the first segment and numbering from 1 to 4, wherein u1%>u3%>u4%> u2% And? ₂ % is negative. 8. The method of claim 7, wherein each of the segments is selected from the group consisting of 0.75 to 1.5 占 퐉, 4.5 to 5.5 占 퐉, 7 to 8 占 퐉, and 9 to 12 占 퐉 starting from the first segment to provide a negative overall dispersion slope Lt; / RTI > Has a Δ% ranging from 1.5 to 2%, from -0.2 to -0.45%, from 0.25 to 0.45% and from 0.05 to 0.25%, starting from the first segment. Claim 8 wherein, a single mode optical waveguide fiber wherein the total dispersion slope is in the range of -0.1 to -5.0 ps / nm ² -km to. The single mode optical waveguide fiber according to claim 1, wherein the clad glass layer has an outer diameter in the range of 125 to 170 탆. A length of a single mode waveguide fiber first having a cut wavelength of less than 1310 nm, a dispersion wavelength of 0 at 1280 to 1350 nm and a total dispersion D _smf at 1550 nm, L _smf ; And Mode waveguide second length L _dc having a total dispersion D _d and a damping coefficient α dB / km, Where the mathematical sum of LsmftDsmf and LdctDd is the same as the preselected value, The non-Dd / a and _Aeff are selected to provide a non-linear identification factor G _n1 in the waveguide fiber link, which is less than or equal to the non-linear identification factor in the first single mode fiber length, L _smf . Waveguide fiber link. 12. The method of claim 11, wherein the preselected value of the mathematical sum is essentially zero, Dd ≤ -150 ps / nm-km, A _{eff is} 30 m ² , and magnification Dd / a is 150 ps / Single mode optical waveguide fiber link. 13. The single mode optical waveguide fiber link of claim 12, wherein said power Dd / a is 250 ps / nm-dB. 12. The single mode optical waveguide fiber link of claim 11, wherein the second length of the single mode waveguide is less than 15% of the optical fiber link. 15. The single mode optical waveguide fiber link of claim 14, wherein the second length of the single mode waveguide is less than 5% of the optical fiber link. A core glass region and a peripheral cladding layer, wherein the core glass region is disposed at a long axial centerline of the waveguide fiber, each waveguide fiber comprising at least three segments having a refractive index profile, the first segment having a waveguide centerline And having a radius r ₁ extending from the centerline to a point of the first segment farthest from the centerline and extending radially outward from the first segment having a relative refractive index% of Δ ₁ % Adjacent adjoining segments each have a radius r _i extending from the centerline to the i-th point farthest from the centerline, i = 2 to n, and n is the relative index of refraction% _i % have, Δ Special treatment of the first value, a _1% transfer is symmetrically positioned with the long axis of optical waveguide fibers, the Δ _i% which is the value of the negative Wherein the clad glass layer surrounds the core glass region with a refractive index n _c that is less than the refractive index of at least a portion of the core glass region, wherein each of the radii r ₁ and r _i and the relative refractive index % ≪ RTI ID = 0.0 > ₁ % _< / RTI > and < RTI ID = 0.0 > Δi% _< / RTI > is selected to provide a pre-selected negative overall dispersion of -150 ps / nm-km at 1550 nm; Drawing the preform to a waveguide fiber having a pre-selected outer diameter at a drawing stress of 100 g or more; Coating the waveguide fibers with at least one layer of a polymeric material; And And heat treating the coated waveguide fibers to essentially eliminate residual stresses in the coating step. ≪ Desc / Clms Page number 21 > 17. The method of claim 16, wherein the preselected waveguide fiber has an outer diameter in the range of about 125 占 퐉 to about 170 占 퐉. 17. The method of claim 16, Winding the waveguide fibers on a spool having a diameter of at least 46 cm with a winding stress of about 20 g or less; Bringing the waveguide fibers into a pre-selected temperature; And fixing said waveguide fibers at a pre-selected temperature for 1 to 10 hours. 19. The method of claim 18 wherein the preselected temperature is at least 30 DEG C above the Tg of the polymer coating.