JP2002090568A - Dispersion corrected single mode waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a dispersion compensation fiber with high negative dispersion value and a large effective area. SOLUTION: A preform to be stretched having a core glass region and a surrounding clad layer is formed and stretched by >=100 g stretching into a waveguide fiber having 125 to 170 μm outer diameter. The waveguide fiber is coated with at least one layer of a polymer material. The coated waveguide fiber is heat treated to substantially remove the residual stress in the coating. The core glass region consists of at least three segments and the surrounding clad layer surrounds the core glass region and has the refractive index nc lower than that of at least a part of the core glass region. The radii r1 and ri and relative refractive index percentages Δ1% and Δi% are selected so as to show negative total dispersion <=-150 ps/nm-km at 1550 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] onset Ming Background present invention, a negative total dispersion is controlled, to an effective area is relatively large single mode optical waveguide fiber.
In particular, single mode waveguides have a total dispersion of less than -100 ps / nm-km.

Several factors have been combined to create a wavelength range from 1500 nm to 1600 nm, most preferably for communication systems with optical waveguide fibers. These factors include: the availability of a reliable laser in a wavelength window around 1550 nm; the invention of an optical fiber amplifier with an optimal gain curve in the wavelength range from 1530 nm to 1570 nm; a system capable of wavelength division multiplexing of signals in this wavelength range. Effectiveness; and the effectiveness of a waveguide fiber with low dispersion to provide very little attenuation over this wavelength range.

[0003] The advantages of these techniques make it possible to construct a multi-channel communication system in which the distance between bases is large when signals are reproduced electronically, and the information speed is very high.

However, many telecommunications equipment lags behind technological advances that make 1550 nm the most preferred working window. These early systems mainly consisted of 13
It was designed for use over a wavelength range centered around 10 nm. This design includes a laser operating at a wavelength around 1310 nm and an optical waveguide having a zero dispersion wavelength around 1310 nm. In these systems,
The waveguide fiber has a local attenuation minimum around 1310 nm, but the theoretical minimum at 1550 nm is about half of the minimum at 1310 nm.

[0005] There have been plans to adapt these old systems to new laser, amplifier, and multiplexing techniques. No. 5,361,319 (Antos et al.),
As further discussed in the literature cited therein, the basic feature of this scheme is that in each waveguide fiber link, a length of waveguide that compensates for the total dispersion of the link at 1550 nm By inserting the fiber, one overcomes the relatively large total dispersion. As used herein, the term "link" refers to a signal source, i.e., a waveguide fiber that spans the distance between a transmitter or electronic signal regenerator and a receiver or another electronic signal regenerator. Is defined.

The patent to Antos et al. Includes about -20 ps / nm-
A dispersion compensating waveguide fiber having a core refractive index profile that provides a dispersion at km of 1550 nm has been described. The common convention of dispersion codes in the prior art is that if shorter wavelength light has a higher velocity in the waveguide, the waveguide dispersion is said to be positive. Since the dispersion at about 1550 nm of a waveguide fiber having a zero dispersion wavelength around 1310 nm is about 15 ps / nm-km, the length of the dispersion-correcting waveguide fiber required to completely correct the total dispersion at 1550 nm is obtained. The length is 0.75 of the original link length. Thus, for example, a 50 km waveguide fiber link would have
It has a total dispersion of ps / nm-km × 50 km = 750 ps / nm. To effectively offset this variance, 750p
A dispersion compensating waveguide fiber having a length of s / nmｋ20 ps / nm-km = 32.5 km is required.

[0007] The additional attenuation introduced into the link by the dispersion compensating waveguide must be canceled by the optical amplifier. Introducing an additional electronic regenerator in the link is not cost effective. In addition, the cost of dispersion compensating waveguide fiber accounts for a large portion of the cost of total waveguide fiber. The required long dispersion compensating waveguide must be formed in an environmentally stable package that can take up a large amount of space.

[0008] Since the design of the compensating waveguide fiber typically has more index modifying dopant in the core region,
The attenuation is typically large for standard waveguide fibers in the link.

[0009] Possibly due to the improved laser and optical amplifiers and the large signal power levels formed by the waveguide division multiplexing scheme, the link length or data transmission rate is likely to be limited by nonlinear optical effects. The strong effect of these nonlinear effects is due to the effective area of the fiber (A
_eff ) can be limited. The effective area is A _eff = 2Π (∫E ² rdr) ² /
(∫E ⁴ rdr), where the integration range is from 0 to ∞, and E is the electric field associated with the propagating light. The distortion for the non-linear effect depends on the formula Pxn ₂ A _eff , where P is the signal power and n ₂ is the non-linear index constant. Therefore, care must be taken in the design of the dispersion compensating waveguide fiber to ensure that the A _eff of the compensating fiber is large enough to ensure that the compensating fiber does not produce significant nonlinear effects in the link. If the A _eff of the compensating fiber is smaller than that of the original fiber in the link, the compensating fiber may be placed at the link position where the signal power is smaller and thus the nonlinear effect is minimal. Also, in many links, A
_The correction fiber with a small _eff is part of the overall link length and does not contribute significantly to the nonlinear distortion of the signal.

Therefore, a part of the link length, for example,
Having a length that is less than 15%, the attenuation is small enough to eliminate the need for additional signal amplification to simply offset the attenuation of the correction waveguide fiber, and the nonlinear dispersion effect in the correction waveguide fiber is the limiting factor Therefore, there is a need for a dispersion-correcting optical waveguide fiber having a sufficiently large effective area so as not to cause the above problem.

Definition— Effective area is A _eff = 2Π (∫E ² rdr) ² /
(∫E ⁴ rdr), where the integration range is from 0 to ∞, and E is the electric field associated with the propagating light.

The nonlinear discriminating factor is given by the equation G _nl = n ₂
/ A _eff (exp [D ₁ × L ₁ D _d / α] -1) / α
Where n ₂ is the nonlinear index of refraction, D ₁ is the dispersion of the wavelength portion optimized for operation around 1310 nm, L ₁ is the length corresponding to D _1, and D ₁ is _d
Is the dispersion of the dispersion compensating fiber, and α is the attenuation of the dispersion compensating fiber. The expression of G _nl are derived from the underlying definition _G nl _~n 2 _{/ A eff} (effective length × output power). The effective length and output power are expressed in terms of waveguide fiber length and attenuation α. The correction waveguide fiber is inserted into the equation with the requirement D ₁ × L ₁ = D _d × L _d . G _nl is a useful quantity to evaluate link efficiency because it is a combination of system factors such as system architecture, amplifier spacing, D _d / α, and n ₂ / A _eff .

SUMMARY OF THE INVENTION The present invention disclosed herein meets the requirements of an improved dispersion-compensating waveguide fiber. Bhagavatula U.S. Pat.
No. 4,715,679 and a segmented core refractive index profile of the type introduced in Liu US patent application Ser. No. 08 / 378,780 have been discovered.

A first aspect of the present invention is a single mode optical waveguide fiber having a central core glass region and a surrounding layer of cladding glass. Core glass area at least 3
It has two segments, each segment being characterized by a refractive index profile, a radius r, and Δ%. %
Definition of the refractive index ^{_{delta,% Δ = [(n 1}} 2 -n c 2) /
2n ₁ ^2] a × 100, where, _{n 1} denotes the refractive index of the core, _{n c} is the refractive index of the cladding. Unless otherwise stated, n ₁ is the maximum refractive index in the core region characterized by% Δ. The radius of each segment is the length measured from the centerline of the waveguide fiber to the point of the segment furthest from this centerline. The refractive index distribution of a segment gives the refractive index value at the radius point of the segment. In this first form of the invention, the delta percent of the first segment, Δ ₁ %, is positive and the Δ% of at least one other segment is negative. The segment radius and Δ% are selected to provide a negative total dispersion at 1550 nm that is less than -150 ps / nm-km.

In the first embodiment, the core glass region has three segments and the second segment has a negative Δ%. A preferred embodiment is
Beginning in the first segment and continuing outwardly, from about 1 to 1.5 μm, 5.5 to 6.5 μm, and 8 to
Each segment having a radius in the range of 9.5 μm, each segment starting from the first segment and continuing outward, and
From 1% to 2%, -0.2 to -0.5%, and 0.2% to 0.5% to provide an effective area A _eff of about 30 μm ² or greater at 1550 nm. Effective areas greater than 60 μm ² can be achieved.

In another embodiment of this first embodiment, the core glass region has four segments, and the second and fourth segments have a negative Δ%. The preferred embodiment is about 1-2 μm, 6-8 μm, 9-11 μm, starting at the waveguide center and continuing outward.
m, and respective radii in the range of 13 to 17 μm. The Δ% of the corresponding segment is
It is in the range of about 1-2%, -0.2 to -0.8%, 0.4 to 0.6%, and -0.2 to -0.8%. These preferred core distributions provide an A _eff at 1550 nm of 30 μm ² or greater. 2 to 15 ps / provided by these core distributions
The dispersion slope of nm-km is suitably small.

In another embodiment of this aspect of the invention, the core glass region has four segments numbered from 1 to 4, starting from the center of the waveguide fiber. Corresponding relative refractive index percent _{segment, Δ 1%> Δ 3%} > Δ 4%> Δ _2% order, delta _2% is negative. Each delta%, 2% from 1.5 regard delta _1%, with respect to delta _2% -0.2 -0.
45%, 0.25 to 0.45% with respect to delta _3% and _delta 4%
Are between 0.05 and 0.25%, and the respective radii associated with these Δ% are about 0.75 to 1.5 for r _1.
μm, with respect to _{r 2 5.5μm} from 4.5, with respect to _{r 3} is a 12μm 8μm, and from 9 to 7. In this embodiment, the total dispersion slope is negative, which serves to offset the positive slope of the original link waveguide fiber operating at the 1310 nm window. Typically, the negative slope of the total dispersion, from about -0.1 to range -5.0ps ^/ nm 2 -km.

A second form of the present invention is made from a first length of single mode fiber designed to operate with a 1310 nm window and a length of dispersion corrected single mode waveguide fiber. A single mode optical waveguide fiber link. The product of the length of the dispersion compensating fiber and the total dispersion at 1550 nm is algebraically added to the dispersion product of the length of the waveguide fiber of the first length times the pre-selected value of the total dispersion for the link. Is chosen to get The preselected value is preferably zero at 1550 nm and may be selected to provide the lowest total dispersion over this window. If four-wave mixing or self-phase modulation is the expected problem for operation of the 1550 nm window, the total dispersion at 1550 nm is
It may be chosen to be a small positive number.

The attenuation of the dispersion compensating waveguide fiber is
Small enough to not be a link data rate limiter
Retained by value. Furthermore, A_effIs the dispersion compensation waveguide
Fiber does not introduce significant nonlinear dispersion effects
Large enough, at least 30μm²Should be
It is. The correction fiber total dispersion and attenuation ratio is A
_effAnd as defined above in the prior art
G_nlAre combined by a function that represents the discriminating factor called
You. This factor is due to the correction waveguide
A measure of fiber characteristics.

An embodiment of this embodiment of the present invention has a value of -150.
Total dispersion D _{d of} ps / nm-km or less, A _eff ≧ 30 μm
² and a dispersion compensating waveguide fiber having a magnitude of D _d / α ≧ 150 ps / nm-dB. In a preferred embodiment, the magnitude of D _d / α is ≧ 250 ps
/ Nm-dB.

Since the total dispersion of the correction fiber is a large negative number, the length of the correction fiber required to reach a preselected value of the total dispersion for the link is typically 15 times the length of the link. % And may be less than 5% of the link length.

A third form of the invention is to reduce the dispersion in the link originally designed for operation in the 1310 nm window to 1550 n.
There is a method of manufacturing a single-mode optical waveguide to be corrected by m. The stretched preform consisting of the central core glass region and the surrounding cladding glass layer may be made by any of the conventional techniques. These techniques include internal and external chemical vapor deposition, axial chemical vapor deposition, and improvements of these techniques in the prior art. This core glass region has the features described in the first embodiment of the present invention. The core region having a positive relative refractive index may be formed in a silica glass matrix using a dopant such as germania. The core region with a negative relative refractive index may be formed using a dopant such as fluorine.

With a stretching tension greater than about 100 grams,
It has been found that a better total dispersion to attenuation ratio is obtained than a similar waveguide fiber drawn at lower tension. An outer diameter of greater than about 125 μm is preferred to limit bending losses. The upper limit of the outer diameter is set by practical limitations such as cost and required cable size. The practical upper limit is about 170 μm.

To limit attenuation due to residual coating stress, the coated waveguide fiber may be loosely wound on a spool and heat treated. For the most effective release of stress, the spool size should be greater than about 45 cm. The winding tension used to wind the waveguide fiber on the spool is less than about 20 grams. A preferred winding method is to cause the waveguide fiber to assume a sagging shape just before winding on a spool.

Glass transition temperature Tg of polymer coating
A heat treatment lasting 1 to 10 hours at a temperature at least 30 ° C. higher than that has been found to be effective in releasing residual coating stress for the thickness and type of coating used in the test. A retention time of about 5 hours has been found to be effective for a thickness of about 60 μm of the UV-cured acrylate coating used to make the waveguide fibers described herein.

It is believed that the heat treatment methods described herein include temperature and time limits suitable for some polymer coating types and thicknesses suitable for use in the manufacture of optical waveguide fibers.

The broad applicability of the core waveguide fiber composed of segments to the more detailed description requirements of the particular communication system of the invention are those derived from the adaptive obtained by core concept whose segments. The number of segments in the core is limited only by the diameter of the core and the narrowest core segment that can affect the propagation of light in the waveguide. Also, for example, the width, arrangement, refractive index distribution, and relative position of the core segment with respect to the center line of the major axis of the waveguide affect the characteristics of the core waveguide fiber composed of the segments. The large number of segment changes and combinations explains the applicability of core designs consisting of segments.

The problem to be solved by the invention disclosed and described herein is to overhaul the system without overhauling the system.
a communication system designed to work with nm windows,
It is to be modified to operate in the 1550 nm wavelength window.
The solution to this problem is a dispersion compensating waveguide fiber that can be easily inserted into a communication link and has full dispersion characteristics, attenuation, and _Aeff to achieve high data rates within the working window around 1550 nm. In particular, the compensating fiber must have a dispersion characteristic that substantially cancels the 1550 nm window dispersion of the 1310 nm portion of the link. The correction fiber should have sufficiently low attenuation that the correction fiber can be inserted into the link without having to regenerate the signal. In some cases, a signal optical amplifier may be required. The A _eff of the correction fiber should be large enough so that the correction fiber is not a data rate limiting member for nonlinear effects.

FIG. 1 shows the refractive index distribution of a general core region satisfying these requirements. Four segments 2, 4, 6, and 8 are shown in this figure. In one embodiment of the invention, segment 8 comprises a cladding
The refractive index is equal to 10 and the core glass region has three segments. The present invention is not limited to a three or four segment core refractive index distribution. However, in terms of manufacturing costs, the simplest distribution that meets the requirements of the system is preferred.

The dashed line 7 shows the changes that can be made within the refractive index distribution of the segment without substantially changing the properties of the waveguide fiber. The corners of the distribution may be rounded. The distribution shape of the center may be, for example, triangular or parabolic. Only one segment needs to have a negative Δ%. Another description of small distribution changes or the strong effects of perturbations is the width on a Δ% basis, and the outer radius of the segment is a more important factor in determining waveguide fiber characteristics.

Table 1 shows the arrangement of core segments and Δ%
1 shows a study of a computer model performed to evaluate the susceptibility of the properties of a waveguide fiber to. Refractive indices 1 to 5 follow the description of the four core region refractive index distributions in FIG. The refractive index distribution 6 is a distribution of three segments having all of the features of FIG. 1 except for the last segment 8.

[0032]

[Table 1] Some of the advantages of this design are shown in Table 1. These features:-For all of the studied refractive index profiles, a large A
_a very large negative dispersion is achieved with _eff ; the cut-off wavelength is relatively insensitive to changes in the parameters of the segment; and reducing the radius of the segment 2 reduces the total dispersion slope. Effective in reducing; and that the three-segment core can meet the requirements of many system geometries.

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

[0034]

[Table 2] The embodiment of the new distribution shown in FIG. 2 again shows four segments, 12, 14, 16 and 18 core glass regions. The cladding glass layer is shown as structure 20. The main features of this design are: the relative refractive index of the central segment is large compared to the design of FIG. 1; there is only one negative relative refractive index portion 14; the radius of the segments 14, 16 and 18 For the design shown in FIG. One of the effects of moving the position of the segment to the waveguide centerline is that A
_{eff is} to be reduced.

The design of the core glass region refractive index distribution 21 follows the design shown in FIG. Refractive index distribution 22 and
23 is similar to the distribution of FIG. 2, except that the Δ% of segment 18 is zero in these two cases. Table 2 shows the results of a computer model study evaluating the properties of the core region refractive index profile that causes a negative total dispersion slope in the dispersion-corrected waveguide fiber. The negative total dispersion slope in the correction waveguide fiber serves to offset at least a portion of the slope of the remaining examples of the link, thereby reducing the link dispersion slope over the working window wavelength of 1550 nm. The data in Table 2 shows that A _eff is small when a negative dispersion slope is achieved. Therefore, this compensation waveguide design should be used when only short lengths of compensation fiber are needed, or when nonlinear dispersion effects are not important, such as those parts of the link where the signal power density is low. is there.

Example-Three-Segment Distribution with Large D _d / α An optical waveguide fiber preform having a three-segment core glass region refractive index distribution as shown in FIG. 3 was prepared. Central segment 22 had a Δ% of 1.83. Segment 24 had a negative Δ% of −0.32%. segment
26 had a relative refractive index of 0.32%. The radius of the segment, read in millimeters from the horizontal axis, may be converted to the equivalent value of the waveguide fiber using the outer diameter of the last waveguide fiber, which was 155 μm. The stretching tension was on average 200 grams. The obtained waveguide fiber was loosely wound around a 46 mm diameter spool and annealed at 50 ° C. for about 10 hours.

The total dispersion is -214 ps / nm-km,
The attenuation is 0.6 dB / km and the D of 356 ps / nm-dB
_d / α. The effective area was 50 μm ² . Preferably, the dispersion slope of the waveguide having this core shape is -2.
To +2 ps / nm ² -km.

In FIG. 4a, G _nl, which is a nonlinear identification factor defined as described above, is plotted against D _d / α. The series of curves 34 obtained gives the ratio D _d
The performance of the system given by / α can be easily predicted.
Referring to the G _nl equation described above, it is clear that G _nl decreases as D _d / α increases.
Thus, from a system perspective, the performance of the waveguide fiber can be inferred from the D _d / α ratio. Also,
The cancellation of dispersion to attenuation in the dispersion compensating fiber is shown in FIG.
It can be read directly from the graph of a. For example, G
Given that a particular system can only operate when nl is less than about 30, the attenuation is 0.29 dB / km and 3.2 dB / k
m, the dispersion of the correction fiber is −15.
It can vary between 0 and -400 ps / nm-km.

The performance of the dispersion compensating waveguide fiber may be evaluated using the graph shown in FIG. 4B. The y-axis is the total loss introduced into the link by the dispersion compensating waveguide fiber. The x-axis is the D _d / α ratio. Assuming that the original system designed for operation of the 1310 nm window has a length of 100 km and a dispersion at 1550 nm of 17 ps / nm-km, curve 34 can be drawn. The significant improvement in contribution loss as Dd / α increases explains the value of this ratio that evaluates the performance of dispersion-corrected waveguide fibers.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a refractive index distribution of a novel core region.

FIG. 2 is a diagram showing another example of a refractive index distribution of a novel core region.

FIG. 3 shows the results of measurements performed on a stretched preform with a novel core distribution embodiment.

FIG. 4 shows a series of curves relating the discriminant to the ratio of total dispersion and attenuation (FIG. 4a), and the dependence of the system loss caused by the correction waveguide fiber on the ratio of total dispersion and attenuation. Curve (FIG. 4b)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor George E. Barkey 14871 Pine City Lily Hill Road, New York, USA 11551 (72) Inventor Daniel W. Khotov United States of America New York 14870 Painted Post Fox Lane Extension 40 (72) Inventor G. Thomas Holmes United States of America New York 14870 Painted Post Overbrook Drive 44 (72) Inventor Yangmin Liu United States of America 14845 Horseheads Glendale Drive 41 F-term (reference) 2H050 AA01 AB03Z AC13 AC38 AD01 AD16

Claims (5)

[Claims] 1. A method of manufacturing a dispersion-compensated single-mode optical waveguide fiber, comprising forming an elongated preform having a core glass region and a surrounding cladding layer, wherein the core glass region includes a longitudinal axis of the waveguide fiber. Consisting of at least three segments each having a refractive index distribution, wherein a first segment is arranged to include the centerline of the waveguide, and from the centerline to the centerline. Additional segments adjacent to each other having a radius r ₁ and a relative refractive index percent Δ ₁ % extending to a point of the furthest first segment extend radially outward from the first segment. the center line i th respective radii r _i and the relative refractive index percent delta _i% extending to a point of the segment farthest from the centerline from = 2
To n, where n is the number of segments, and wherein the first segments are symmetrically arranged around the long axis of the optical waveguide fiber, Δ ₁ % is positive, and at least 1 one segment is assumed to have the _i% negative delta, the surrounding cladding layer, surrounding said core glass region, and having at least a portion of the refractive index lower than the refractive index n _c of the core glass region, each The radii r ₁ and r _i and the relative refractive index percentages Δ ₁ % and Δ _i % are selected to provide a negative total dispersion at 1550 nm of -150 ps / nm-km or less; The fiber is drawn into a waveguide fiber having an outer diameter in the range of 170 μm, and the drawing tension at that time is
100 g or more, the method comprising coating the waveguide fiber with at least one layer of a polymer material, and heat-treating the coated waveguide fiber to substantially remove residual stress in the coating. And how. 2. The heat treatment step comprises: winding the waveguide fiber around a spool having a diameter of at least 46 cm, wherein the winding tension is 20 g or less, and the waveguide fiber is made of the polymer material. Tg of coating
3. The method of claim 1 including raising the temperature of the waveguide fiber to at least 30 ° C. above and maintaining the waveguide fiber at the temperature for a period ranging from 1 to 10 hours. 3. A method of manufacturing a dispersion-compensated single-mode optical waveguide fiber, comprising: forming an elongated preform having a core glass region and a surrounding cladding layer, wherein the core glass region includes a longitudinal axis of the waveguide fiber. Consisting of three segments, each having a refractive index distribution, disposed about a centerline of the waveguide, wherein a first segment is arranged to include a centerline of the waveguide;
Additional segments adjacent to each other having a radius r ₁ and a relative refractive index percentage Δ ₁ % extending from the centerline to a point of the first segment located furthest from the centerline, the first segment I extending radially outwardly from and located furthest from said centerline to said centerline
A respective radius r _i extending to the point of the th segment
And the relative refractive index percent Δ _i %, i = 2 to n, where n is the number of segments, wherein the surrounding cladding layer surrounds the core glass region and includes at least a portion of the core glass region. shall have a refractive index lower than the refractive index n _c, the first segment is symmetrically disposed about the longitudinal axis of the optical waveguide fiber, beginning at the first segment, each segment toward the outside , 1 to 1.5
starting at the first segment and having a radius in the range of 5.5 to 6.5 μm, and 8 to 9.5 μm, each outwardly directed segment has a radius of 1.5 to 2%, −0.2
From -0.5%, and Δ% in the range of 0.2 to 0.5%, negative total dispersion at 1550 nm below -150 ps / nm-km and effective area A _eff at 1550 nm above 30 μm ^2.
The preform is drawn into a waveguide fiber having an outer diameter in the range of 125 μm to 170 μm, and the drawing tension at that time is
100 g or more, the method comprising coating the waveguide fiber with at least one layer of a polymer material, and heat-treating the coated waveguide fiber to substantially remove residual stress in the coating. And how. 4. A method of manufacturing a dispersion-compensated single mode optical waveguide fiber, comprising forming a stretched preform having a core glass region and a surrounding cladding layer, wherein the core glass region comprises a major axis of the waveguide fiber. Consisting of four segments, each having a refractive index distribution, disposed about a centerline of the waveguide, wherein a first segment is positioned to include the centerline of the waveguide;
Additional segments adjacent to each other having a radius r ₁ and a relative refractive index percentage Δ ₁ % extending from the centerline to a point of the first segment located furthest from the centerline, the first segment I extending radially outwardly from and located furthest from said centerline to said centerline
A respective radius r _i extending to the point of the th segment
And the relative refractive index percent Δ _i %, i = 2 to n, where n is the number of segments, wherein the surrounding cladding layer surrounds the core glass region and includes at least a portion of the core glass region. shall have a refractive index lower than the refractive index n _c, the first segment is symmetrically disposed about the longitudinal axis of the optical waveguide fiber, beginning at the first segment, each segment toward the outside 1 to 2μ
m, 6 to 8 μm, 9 to 11 μm, and 13 to 17 μm
Starting at the first segment and having a radius in the range of 1 to 2
%, -0.2 to -0.8%, 0.4 to 0.6%, and -0.2 to-
With a% in the range of 0.8%, -150 ps / nm-km
Negative total dispersion at 1550 nm below and 15 μm above 30 μm ²
Providing an effective area A _eff at 50 nm, stretching said preform into a waveguide fiber having an outer diameter in the range of 125 μm to 170 μm, wherein the stretching tension is
100 g or more, the method comprising coating the waveguide fiber with at least one layer of a polymer material, and heat-treating the coated waveguide fiber to substantially remove residual stress in the coating. And how. 5. A method of manufacturing a dispersion-compensated single-mode optical waveguide fiber, comprising forming a stretched preform having a core glass region and a surrounding cladding layer, wherein the core glass region includes a longitudinal axis of the waveguide fiber. Consisting of four segments, each having a refractive index distribution, disposed about a centerline of the waveguide, wherein a first segment is positioned to include the centerline of the waveguide;
Additional segments adjacent to each other having a radius r ₁ and a relative refractive index percentage Δ ₁ % extending from the centerline to a point of the first segment located furthest from the centerline, the first segment I extending radially outwardly from and located furthest from said centerline to said centerline
A respective radius r _i extending to the point of the th segment
And the relative refractive index percent Δ _i %, i = 2 to n, where n is the number of segments, wherein the surrounding cladding layer surrounds the core glass region and includes at least a portion of the core glass region. shall have a refractive index lower than the refractive index n _c, the first segment is symmetrically disposed about the longitudinal axis of the optical waveguide fiber, it said core glass region has four segments, the said segments , Are sequentially numbered from 1 to 4 such that the first segment is 1, and Δ
A _{1%> Δ 3%> Δ} 4%> Δ 2%, each segment starting with the first segment, from 1 to 0.75.
5 μm, 4.5 to 5.5 μm, 7 to 8 μm, and 9 to 1
Each segment having a radius in the range of 2 μm and beginning with the first segment is 1.5 to 2%, −0.2
To -0.45%, 0.25 to 0.45%, and 0.05 to 0.25%
Δ% in the range of −150 ps / nm-km or less.
Providing a negative total dispersion at 1550 nm and a negative total dispersion slope, stretching the preform into a waveguide fiber having an outer diameter in the range of 125 μm to 170 μm, wherein the stretching tension is
100 g or more, the method comprising coating the waveguide fiber with at least one layer of a polymer material, and heat-treating the coated waveguide fiber to substantially remove residual stress in the coating. And how.