JP2002243996A - Dispersion compensating fiber, dispersion compensating fiber unit, and dispersion compensator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the variation of transmission loss due to temperature change caused by the heat cycle of a dispersion compensating fiber unit using a dispersion compensating fiber and a dispersion compensator. SOLUTION: In the dispersion compensating fiber 3 in which a seathing 2 is applied to the circumference of an optical fiber 1 made of silica glass, the sheathing 2 consists of an inner layer seathing 2a, outer layer seathing 2c, and a lubricating layer 2b provided in between. The pull-out force between the optical fiber 1 and the inner layer sheathing 2a is 5N or higher, and the pull-out force between the inner layer sheathing 2a and the outer layer sheathing 2c is within the range of 0.1 N to 5.0 N.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a dispersion compensating fiber, a dispersion compensating fiber unit, and a dispersion compensator used for reducing transmission distortion caused by chromatic dispersion of an optical fiber transmission line.

[0002]

2. Description of the Related Art To perform long-distance and large-capacity optical transmission in the 1.55 μm band using a single-mode optical fiber having a zero-dispersion wavelength in the 1.3 μm band, chromatic dispersion in the 1.55 μm band is reduced. A canceling dispersion compensator has been developed (Japanese Patent Laid-Open No. Hei 10-123342). Such a dispersion compensator is composed of a single-mode optical fiber having a zero-dispersion wavelength in the 1.3 μm band and a long dispersion compensating fiber having a chromatic dispersion in the 1.55 μm band and a chromatic dispersion having an opposite sign to the chromatic dispersion in the 1.55 μm band. It is wound around a small bobbin and made compact.

[0003] FIG.
FIG. 1 is a cross-sectional view showing an example of a dispersion compensating fiber described in Japanese Unexamined Patent Publication, No. 21: optical fiber made of silica-based glass; 21a, a core portion; 21b, a depressed cladding portion; 21c, an outer cladding portion; Is an inner layer coating, 23 is an outer layer coating, and 24 is a coating. FIG. 7B is a diagram showing a refractive index distribution of the optical fiber 21 in the radial direction. The optical fiber 21 includes a core portion 21a having a central refractive index higher by Δ + than that of quartz glass, a depressed cladding portion 21b surrounding the core portion having a refractive index lower by Δ− than quartz glass, and a quartz glass around the core portion 21a. And an outer cladding portion 21c having the same refractive index.

The inner coating 22 and the outer coating 23 of the coating 24 on the optical fiber 21 are each made of an ultraviolet curable resin such as urethane acrylate resin.
2 is a resin having a relatively low Young's modulus, the outer layer coating 23 is made of a resin having a relatively high Young's modulus, the outer diameter of the optical fiber 21 is about 100 μm, the outer diameter of the inner layer coating 22 is 140 μm,
The outer diameter of the outer coating 23 is 180 μm. The thickness of the inner coating 22 and the outer coating 23 is 20 μm, respectively.

In constructing a dispersion compensator, 500
Since a long dispersion compensating fiber having a length of m or more is wound around a bobbin having a small body diameter, there is a problem in that laterally or vertically adjacent dispersion compensating fibers apply side pressure to each other, thereby increasing transmission loss. To cope with this problem, in the technique described in Japanese Patent Application Laid-Open No. 10-123342, after a dispersion compensating fiber is wound around a bobbin, the bobbin is taken out or the bobbin body diameter is reduced to reduce the dispersion compensation. Move the fiber away from the bobbin barrel.

The state in which the dispersion compensating fiber is merely pulled out of the bobbin is a mass state in which the dispersion compensating fibers are tightly adhered to each other, and this state is called a coil here. If this coil is vibrated or the coil is twisted with both hands, the degree of adhesion between the dispersion compensating fibers is loosened and the wound state is deformed, and the dispersion compensating fibers are in a state where they are not tightly adhered. Are called bundles here. When the dispersion compensating fiber is in the coil state, the transmission loss increases due to the side pressure due to the close contact of the dispersion compensating fibers, but by loosening the degree of close contact to form a bundle, the side pressure exerted by the dispersion compensating fibers decreases,
An increase in transmission loss is suppressed.

[0007]

However, since the dispersion compensating fiber in a bundle state is in a state in which it can move freely, the shape of the bundle is easily deformed by vibration or impact, and a bending loss is caused by the deformation of the bundle. There is. In order to suppress this deformation, a method of fixing the bundle at a plurality of positions in the housing is described in JP-A-10-123342. And local bending losses may occur. Further, since the bundle is locally fixed, a change in transmission loss when a temperature change is given by a heat cycle is large.

The present invention provides a dispersion compensating fiber, a dispersion compensating fiber unit, and a dispersion compensator which solve the above-mentioned problems of the prior art.

[0009]

A dispersion compensating fiber according to the present invention is a dispersion compensating fiber in which a coating is provided around an optical fiber made of silica glass, and the coating is provided between an inner coating and an outer coating. A pull-out force between the optical fiber and the inner layer coating is 5N or more, and a pull-out force between the inner layer coating and the outer layer coating is in a range of 0.1N to 5.0N. There is something.

Further, the dispersion compensating fiber unit of the present invention comprises a plurality of dispersion compensating fibers arranged along a steel wire,
The steel wire and the dispersion compensating fiber are filled and covered with a protective layer having a Young's modulus at room temperature of 500 MPa or less.

Further, the dispersion compensator of the present invention accommodates the dispersion compensating fiber in a housing as a coil or a bundle,
The periphery of the dispersion compensating fiber in the housing is filled with a filling material having a Young's modulus at room temperature of 50 MPa or less.

Thus, it is possible to reduce the amount of change in transmission loss with respect to temperature change due to a heat cycle in the dispersion compensating fiber unit and dispersion compensator using the dispersion compensating fiber of the present invention.

The measurement of the pull-out force is performed by the following method. 6A and 6B are diagrams for explaining the measurement method. FIG. 6A is a plan view when a sample to be measured is fixed, FIG. 6B is a cross-sectional view along XX, and FIG. ) Is a YY cross-sectional view. In FIG. 6, 1 is an optical fiber, 2
Is a coating, 2a is an inner coating, 2b is a lubricating layer, 2c is an outer coating, 3 is a dispersion compensating fiber, 11 is a pattern paper, and 12 is an adhesive.

The procedure for measuring the pull-out force is as follows. (1) A dispersion compensating fiber 3 (sample) having a length of 160 mm is collected. (2) Two 25 mm × 25 mm patterns 11 are prepared. (3) As shown in FIG. 6A, both ends of the dispersion compensating fiber 3 to be measured are adhered and fixed with the adhesive 12 along the pattern 11. The adhesive 12 is Alon Alpha (trade name). (4) The dispersion compensating fiber 3 to be measured and the adhesive 12 are cut with a knife at a position (a position in the XX cross section) 10 mm into the pattern side from the inside (a position in the YY cross section) of one of the patterns. . (The pattern is not cut. It is also desirable to bend the pattern at that portion to confirm that the portion of the optical fiber 1 made of quartz glass of the dispersion compensating fiber 3 to be measured has been cut reliably.) (5) A) A cut is made with a razor on the coating 2 of the dispersion compensating fiber 3 on the inner side (at the Y-Y section) of one of the patterns. The depth of the cuts in the case of measuring the pullout force between the optical fiber 1 and the inner coating 2a is, L ₂ -L ₂ shown in FIG. 6 (C)
Up to the line. That is, the cut is made to the vicinity of the middle of the thickness of the inner layer coating 2a, but the cut is not made in the optical fiber 1 made of quartz glass. The depth of the cuts in the case of measuring the pullout force between the inner layer cover 2a and an outer layer covering 2c is up to L ₁ -L ₁ line in FIG. 6 (C). That is, the outer layer coating 2c is cut to near the middle of its thickness so that no cut is made in the inner layer coating 2a. (6) Both patterns 11 are fixed to the chuck of the Tensilon type tensile tester, and a tensile test is performed at a pulling speed of 5 mm / min. In addition, the optical fiber 1 and the inner layer coating 2
When measuring the pullout force between a and
m optical fibers 1 come out of the coating 2. When measuring the pull-out force between the inner coating 2a and the outer coating 2c, the optical fiber 1 having a length of 10 mm is pulled out of the outer coating 2c while being covered with the inner coating 2a.

The Young's modulus of the filling material or the protective layer is determined by taking a No. 3 type test piece according to JIS K 7113 from a resin sheet and conducting a tensile test. The tensile rate in the tensile test is 2 mm / min, the sample temperature and the measurement temperature are 23 ° C., the measurement environment relative humidity is 50% RH, and the Young's modulus is determined using a 2.5% secant formula. The determination is made based on the average value of five samples.

[0016]

1 is a cross-sectional view showing an embodiment of a dispersion compensating fiber according to the present invention, wherein 1 is an optical fiber, 2 is a coating, 2a is an inner coating, 2b is a lubricating layer,
c is an outer layer coating, and 3 is a dispersion compensating fiber. FIG. 2A is a cross-sectional view illustrating an example of the optical fiber 1, and FIG. 2B illustrates an example of a refractive index distribution of the optical fiber 1 in a radial direction. In FIG. 2, reference numeral 1 denotes an optical fiber, 1a denotes a core, 1b denotes a depressed clad, and 1c denotes an outer clad.

As shown in FIG. 2B, for example, the optical fiber 1 has a core portion 1a having a central refractive index higher by Δ + than that of quartz glass and a core portion surrounding the core portion by Δ− compared with that of silica glass. It is composed of a low depressed cladding 1b and an outer cladding 1c having the same refractive index as the surrounding quartz glass.

In an example of an optical fiber used as a dispersion compensating fiber for a dispersion compensator, the outer diameter of the core 1a is 2.
7 μm, outer diameter of depressed cladding 1b is 6.6μ
m, the outer diameter of the outer cladding 1c is 125 μm,
Δ + indicating the change rate of the refractive index is 1.9%, and Δ− is −0.4.
%. The chromatic dispersion, chromatic dispersion slope, and transmission loss of this optical fiber are -120 ps / nm / km and -0.28 ps / at a wavelength of 1.55 μm, respectively.
nm ^{2 /} km and 0.40 dB / km. Further, in an example of the optical fiber used for the dispersion compensating fiber for the dispersion compensating fiber unit, the outer diameter of the core portion 1a is 3.8 μm,
The outer diameter of the depressed cladding part 1b is 7.5 μm, the outer diameter of the outer cladding part 1c is 125 μm, Δ + indicating the rate of change of the refractive index is 1.4%, and Δ− is −0.4%. . The chromatic dispersion, chromatic dispersion slope, and transmission loss of this optical fiber are -45 ps / nm / km and -0.07 ps / nm ^{2 at} a wavelength of 1.55 μm, respectively.
/ Km, 0.27 dB / km.

Although an example of a double clad structure has been described above as an optical fiber, any other optical fiber having a dispersion compensation function may be used, and an optical fiber generally called a segment type may be used. Further, the present invention can be applied to a case where a dispersion compensation function is provided by using an optical fiber that propagates a higher-order mode at a wavelength of 1.55 μm.

As shown in FIG. 1, a coating 2 is applied on the optical fiber 1 to form a dispersion compensating fiber 3. The coating 2 is composed of an inner coating 2a and an outer coating 2c and a lubricating layer 2b provided therebetween. Further, a further layer may be provided outside the outer coating layer 2c as necessary. Each of the inner layer coating 2a and the outer layer coating 2c is made of an ultraviolet curable resin such as urethane acrylate resin.
a is a resin having a relatively low Young's modulus, and the outer layer coating 2c is formed of a resin having a relatively high Young's modulus. For example, inner layer coating 2
The Young's modulus of a is 1 MPa, and the Young's modulus of the outer layer coating 2c is 800 MPa.

The lubricating layer 2b is made of silicone oil,
It is composed of highly lubricating substances such as petroleum jelly, animal and vegetable oils, dibasic esters, graphite, molybdenum disulfide, talc, grease and the like. The outer diameter of the optical fiber 1 is about 125 μm, and the thickness of the inner layer coating 2 a is 15 μm to 3 μm.
About 5 μm, the thickness of the lubrication layer 2 b is about 1 μm to 5 μm,
The thickness of the outer layer coating 2c is about 15 μm to 20 μm.
The outer diameter of the dispersion compensating fiber 3 is 180 μm to 245.
It is about μm, but may be smaller.

The pull-out force between the optical fiber 1 and the inner layer coating 2a is set to 5N or more. To change the pull-out force between the optical fiber 1 and the inner coating 2a, the amount of the silane coupling agent added to the inner coating 2a may be adjusted. Further, the pull-out force between the inner layer coating 2a and the outer layer coating 2c is adjusted to be in the range of 0.1N to 5.0N. To change the pullout force between the inner coating 2a and the outer coating 2c, the material and thickness of the lubricating layer 2b may be adjusted. When silicone oil is used as the material of the lubricating layer 2b, when the thickness is about 1 μm, the pull-out force between the inner coating 2a and the outer coating 2c is about 6N, and when the thickness is about 2 μm, the inner coating is about 2 μm. The pull-out force between the inner coating 2a and the outer coating 2c is about 4N, and when the thickness is about 5 μm, the pull-out force between the inner coating 2a and the outer coating 2c is about 1N.

If the pull-out force between the optical fiber 1 and the inner layer coating 2a is smaller than 5N, the degree of adhesion between the inner layer coating 2a and the optical fiber 1 becomes low, and the strength of the optical fiber against bending decreases. Absent. The pull-out force between the inner coating 2a and the outer coating 2c is 0.1 N.
If it is smaller than this, the outer layer coating 2c becomes slippery on the inner layer coating 2a, and the outer layer coating is wavy due to rewinding, and the coating cannot be removed neatly during connection work, which is not preferable. On the other hand, if the pullout force between the inner coating 2a and the outer coating 2c is larger than 5.0 N, the amount of change in transmission loss at the time of temperature change is not preferable, as described in the embodiment.

FIG. 3 is a cross-sectional view showing an embodiment of the dispersion compensating fiber unit according to the present invention, wherein 3 is a dispersion compensating fiber, 4 is a steel wire, and 5 is a protective layer. This dispersion compensating fiber unit is made of a thermosetting resin such as a silicone resin, a butadiene rubber or a silicone rubber-based high-viscosity jelly admixture, or an ultraviolet-curing type resin. The space between the steel wire 4 and the dispersion compensating fiber 3 is filled and covered with a protective layer 5 made of resin. The protective layer 5
Another coating layer may be provided on the substrate.

When the number of the dispersion compensating fibers 3 is eight, the outer diameter of the steel wire is about 0.6 mm, and the outer diameter of the protective layer is 2.6 mm.
Degree. The Young's modulus of the protective layer 5 at room temperature is 50
It is desirable that the pressure be 0 MPa or less in order to suppress the amount of change in transmission loss when the temperature changes. The Young's modulus of the protective layer can be changed by adjusting the crosslinking point of the resin used. This dispersion compensating fiber unit is usually housed in an optical cable, and the optical cable is used after being extended.

FIG. 4 shows an embodiment of the dispersion compensator according to the present invention. FIG. 4 (A) is a plan view of the internal structure, and FIG. 4 (B) is a sectional view in the X direction. In FIG. 4, 3 is a dispersion compensating fiber, 6 is a housing, and 7 is a filling material. This dispersion compensator is configured such that the dispersion compensating fiber 3 is housed in a housing 6 as a coil or a bundle, and the periphery of the dispersion compensating fiber 3 in the housing 6 is filled with a filling material 7. When the dispersion compensating fiber 3 is used as a coil,
For example, a dispersion compensating fiber 3 having a length of about
The coil may be wound around a bobbin of about mm, the body of the bobbin may be pulled out, and the dispersion compensating fibers may be brought into close contact with each other to form a coil. Further, if the coil is vibrated or held by both hands and twisted, the state of tight contact between the dispersion compensating fibers is loosened and the wound state is deformed, so that the bundle of the dispersion compensating fibers 3 is formed. Regardless of whether the coil or bundle is housed in the housing, the entire coil or bundle is uniformly held by the filling material filled around it, so that fluctuations in transmission loss during the heat cycle can be reduced. In the case where the fibers are accommodated in a bundle, the filler material spreads to the gap between the dispersion compensating fibers, so that the transmission loss difference during the heat cycle can be further reduced.

As the filling material 7, a thermosetting resin such as silicone resin, butadiene rubber or a highly viscous jelly admixture based on silicone rubber, or an ultraviolet curable resin can be used. The Young's modulus of the filling material 7 at room temperature is desirably 50 MPa or less in order to suppress the amount of change in transmission loss when the temperature changes. The Young's modulus of the filling material can be changed by adjusting the crosslinking point of the resin.

When the same material as the material used for the lubricating layer of the dispersion compensating fiber 3 is used as the filling material 7, for example, when the material of the lubricating layer is silicone oil, the lubricating material can be lubricated by adding silicone oil to the filling material. The material of the layer can be prevented from seeping out of the surface of the dispersion compensating fiber and decreasing. Further, since the silicone oil has good compatibility with the silicone resin as the filling material, the silicone oil can be easily added to the silicone resin and does not hinder the curing of the silicone resin as the filling material.

[0029]

EXAMPLE A dispersion compensating fiber having the coating shown in FIG. 1 provided on the optical fiber shown in FIG. 2 described above was produced. The optical fiber used for the dispersion compensating fiber for the dispersion compensating fiber unit and the optical fiber used for the dispersion compensating fiber for the dispersion compensator have the refractive index distributions of the core portion and the depressed clad portion as exemplified above. I changed it. The lubricating layer was formed of silicone oil, and by changing the thickness of the lubricating layer, various types of dispersion compensating fibers having a pull-out force between the inner coating and the outer coating were obtained.

The pull-out force between the optical fiber and the inner layer coating was adjusted by the amount of the silane coupling agent added to the inner layer coating. A dispersion compensating fiber unit and a dispersion compensator were manufactured using the completed dispersion compensating fibers having various pull-out forces. As the protective layer of the dispersion compensating fiber unit and the filling material of the dispersion compensator, a silicone resin to which silicone oil was added was used. Also,
A silicone resin having variously changed Young's modulus at room temperature by adjusting the crosslinking point of the silicone resin was prepared and used. The length of the dispersion compensating fiber of the dispersion compensating fiber unit and the dispersion compensator was 5 km each.

The difference in transmission loss due to the heat cycle was determined as follows. Place the completed dispersion compensating fiber unit and dispersion compensator in a thermostat,
Hold for 5 hours at + 70 ° C for 5 hours → Repeat the heat cycle at -20 ° C for 5 cycles, and within 1 hour before the end of the 5 hour holding time at each temperature, 1.55 μm wavelength each
The transmission loss was measured by using, and a value obtained by subtracting the minimum value from the maximum value of the measured values was defined as a transmission loss difference.

By combining three types of dispersion compensating fibers with different pull-out forces between the inner layer coating and the outer layer coating and two types of protective layer materials with different Young's modulus at room temperature, five types of dispersion compensating fiber units are formed. Obtained. The results of measuring the transmission loss difference during the heat cycle for these five types of dispersion compensating fiber units are shown in Table 1 for case number 1.
~ 5. According to this, the transmission loss difference of case numbers 1 to 4 is satisfactory when the transmission loss difference is 0.0005 dB / km or less, but the transmission loss difference of case number 5 is as large as 0.0010 dB / km. In the case of the dispersion compensating fiber unit, the transmission loss difference is 0.0005 dB /
If it exceeds km or more, it is treated as defective, and case number 5 is defective. The cause is considered to be that the pull-out force between the inner layer coating and the outer layer coating is as large as 6N.

Further, from the results of the transmission loss differences of Case Nos. 1 to 4, it can be seen that the transmission loss difference increases as the Young's modulus of the protective layer at room temperature increases. In the case of case numbers 2 and 4, the Young's modulus of the protective layer at room temperature is 600 MP.
a, the transmission loss difference is as good as 0.0005 dB / km, but at the very end of the upper limit range. Therefore, the Young's modulus of the protective layer at room temperature is desirably 500 MPa or less.

[0034]

[Table 1]

Nine types of dispersion compensators were obtained by combining seven types of dispersion compensating fibers with different pull-out forces or coating outer diameters and three types of filler materials with different Young's moduli at room temperature. In each of the dispersion compensators, the dispersion compensating fibers were housed in the casing in a bundle state, and the periphery thereof was filled with a filling material. And the result of having measured the transmission loss difference at the time of a heat cycle about these nine types of dispersion compensators is as the case numbers 11-19 of Table 2. According to this, the case numbers 11 to 16, 18, and 19 are:
In all cases, the transmission loss difference is small at 0.025 dB / km or less, whereas the transmission loss difference in case No. 17 is 0.15 dB / km.
It is as large as 035 dB / km. In the case of a dispersion compensator, a case in which the transmission loss difference exceeds 0.025 dB / km is treated as a failure, and thus case number 17 is a failure. In the case of case number 11, peeling was observed between the optical fiber and the inner layer coating, which was also defective.

It is considered that the cause of these defects is that in case No. 17, the pull-out force between the inner layer coating and the outer layer coating is as large as 6N. For case number 11,
This is probably because the pullout force between the optical fiber and the inner layer coating was as small as 4N. Case numbers 13 and 1
From the comparison of No. 4 and the comparison of Case Nos. 15 and 16, it can be seen that in any case, if the Young's modulus of the filling material at room temperature increases, the transmission loss difference increases. In case number 16, the Young's modulus of the filling material at room temperature is 60.
MPa, and the transmission loss difference is 0.025 dB / km, which is very close to the upper limit range. Therefore, the Young's modulus of the filling material at room temperature is desirably 50 MPa or less.

In case numbers 11 to 17, the outer diameter of the dispersion compensating fiber is 185 μm, whereas in case numbers 18 and 19, the outer diameter of the dispersion compensating fiber is 245 μm. Also in case numbers 18 and 19, the transmission loss difference is good, so that the outer diameter of the dispersion compensating fiber is 24
Even if the diameter is relatively large as 5 μm, the outer diameter is 185 μm.
It can be seen that the transmission loss difference can be reduced as in the case of m.

[0038]

[Table 2]

In the dispersion compensators shown in Table 2, the case numbers 14, 15, wherein the pull-out force between the optical fiber and the inner layer coating and the Young's modulus of the filling material are the same and the pull-out force between the inner layer coating and the outer layer coating are different. FIG. 5 is a graph showing the relationship between the pullout force between the inner layer coating and the outer layer coating and the transmission loss difference for No. 17. According to this graph, when the pull-out force between the inner layer coating and the outer layer coating is approximately 5 N or less, the transmission loss difference is good at 0.025 dB / km or less.

[0040]

The dispersion compensating fiber of the present invention is a dispersion compensating fiber in which a coating is provided around an optical fiber made of silica glass, and the coating comprises an inner coating, an outer coating, and a lubricating layer provided therebetween. Wherein the pull-out force between the optical fiber and the inner layer coating is 5N or more, and the pull-out force between the inner layer coating and the outer layer coating is 0.1N.
Since it is in the range of 5.0 to 5.0 N, the amount of change in transmission loss with respect to temperature change due to a heat cycle in the dispersion compensating fiber unit and dispersion compensator using this dispersion compensating fiber can be reduced.

Also, by setting the Young's modulus of the protective layer of the dispersion compensating fiber unit at room temperature to 500 MPa or less and the filling material of the dispersion compensator at room temperature to 50 MPa or less, the temperature change due to the heat cycle can be prevented. The amount of change in transmission loss can be further reduced.
Further, if the same material as the material used for the lubricating layer of the dispersion compensating fiber is added to the filling material, it is possible to prevent the material of the lubricating layer from seeping into the surface of the dispersion compensating fiber and decreasing.

[Brief description of the drawings]

FIG. 1 is a transverse sectional view showing an embodiment of a dispersion compensating fiber according to the present invention.

FIG. 2A is a cross-sectional view showing an example of an optical fiber used for a dispersion compensating fiber, and FIG. 2B shows a refractive index distribution of the optical fiber in a radial direction.

FIG. 3 is a cross-sectional view showing an embodiment of the dispersion compensating fiber unit according to the present invention.

FIGS. 4A and 4B show an embodiment of a dispersion compensator according to the present invention, wherein FIG. 4A is a plan view of an internal configuration, and FIG.

FIG. 5 is a graph showing a relationship between a pull-out force between an inner layer coating and an outer layer coating and a transmission loss difference.

6A and 6B are diagrams illustrating a method of measuring a pull-out force, wherein FIG. 6A is a plan view when a sample to be measured is fixed,
(B) is an XX sectional view, and (C) is a YY sectional view.

FIG. 7A is a cross-sectional view showing an example of a conventional dispersion compensating fiber, and FIG. 7B is a diagram showing a radial refractive index distribution of an optical fiber used therein.

[Explanation of symbols]

 1: optical fiber 1a: core 1b: depressed clad 1c: outer clad 2: coating 2a: inner coating 2b: lubricating layer 2c: outer coating 3: dispersion compensating fiber 4: steel wire 5: protective layer 6: housing Body 7: Filling material 11: Pattern 12: Adhesive

Claims (6)

[Claims] 1. A dispersion compensating fiber in which a coating is provided around an optical fiber made of quartz glass, the coating comprising an inner coating, an outer coating, and a lubricating layer provided therebetween.
Dispersion characterized in that a pullout force between the optical fiber and the inner layer coating is 5N or more, and a pullout force between the inner layer coating and the outer layer coating is in a range of 0.1N to 5.0N. Compensating fiber. 2. A steel wire comprising a plurality of the dispersion compensating fibers according to claim 1 having a Young's modulus at room temperature of 500 MPa.
A dispersion compensating fiber unit, wherein the surroundings of the steel wire and the dispersion compensating fiber are filled and covered with the following protective layer. 3. The dispersion compensating fiber according to claim 1 is housed in a housing in the form of a coil or a bundle, and the periphery of the dispersion compensating fiber in the housing is filled with a filling material having a Young's modulus at room temperature of 50 MPa or less at room temperature. A dispersion compensator characterized in that: 4. The dispersion compensator according to claim 3, wherein the dispersion compensating fiber housed in the housing is a bundle. 5. The dispersion compensator according to claim 3, wherein the same material as the material of the lubricating layer is added to the filling material. 6. The dispersion compensator according to claim 5, wherein a material of the lubricating layer is silicone oil.