JP2003255170A - Dispersion compensating optical fiber and dispersion compensating optical fiber module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersion compensating optical fiber with a sufficient dispersion slope compensation characteristic even for a non-zero dispersion shifted optical fiber which requires large RDS for dispersion compensation by making the absolute value of a dispersion slope large on a negative side while maintaining the absolute value of wavelength dispersion. <P>SOLUTION: The dispersion compensating optical fiber is manufactured; the radius (c) of a ring core 3 being 6.5 to 9.5 μm; the b/a of a depressed core radius to a center core radius being 2.0 to 4.0 and the c/b of the ring core radius to the depressed core radius being 1.1 to 2.0; and the specific refractive index difference Δ1 of a center core 1 from a clad 4 being +1.00 to +1.90%, the specific refractive index difference Δ2 of the depressed core 2 from the clad 4 being -0.60 to -1.00%, and the specific refractive index difference Δ3 of the ring core 3 from the clad 4 being +0.20 to +1.00%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion compensating optical fiber and a dispersion compensating optical fiber module, and more particularly,
Non-zero dispersion-shifted optical fiber (Non-Ze) having chromatic dispersion of several ps / nm / km around 1.55 μm wavelength band
ro Dispersion Shifted Fib
er, hereinafter abbreviated as “NZ-DSF”. ) Applied to the above) and a dispersion compensation optical fiber module.

[0002]

2. Description of the Related Art Due to the practical use of erbium-doped optical fiber amplifiers, systems using optical amplifiers such as ultra-long-distance unregenerative repeaters have already been commercialized in the wavelength band of 1.53 to 1.63 μm. In addition, with the increase in communication capacity, the development of wavelength division multiplexing transmission has been rapidly advanced, and some transmission lines have already been commercialized.In the future, the wavelength band will be broadened and the number of wavelength division multiplexing will increase rapidly. It seems to proceed. Assuming high-speed transmission, it is desirable for these transmission lines to be optical fibers whose chromatic dispersion is as small as possible in the transmission band and whose chromatic dispersion does not become zero in order to suppress nonlinear effects. Also, for wavelength division multiplexing transmission, the gain difference due to the erbium-doped optical fiber amplifier in the used band is as small as possible, the chromatic dispersion is also small to some extent, and the difference in the dispersion value between each wavelength in the used wavelength band is In order to make it as small as possible, it is also important that the rate of change in dispersion with respect to the change in wavelength in the entire transmission line (hereinafter referred to as “dispersion slope”) is small.

In recent long-distance systems, many wavelengths are used.
The power of light propagating in the optical fiber
Non-linear effect that causes deterioration of transmission characteristics due to rapid increase
The suppression technology of is essential. The magnitude of this nonlinear effect is n_Two/ A_eff It is represented by. Where n_TwoIs the nonlinear refraction of an optical fiber
Rate, A_effIs the effective area of the optical fiber. non-linear
To reduce the effect, n_TwoOr make A
_effNeeds to be large, but n_TwoOptical fiber
Since it is a value specific to the constituent material, it is a silica-based optical fiber.
However, it is difficult to reduce it significantly. for that reason,
The development of the current nonlinear effect suppression optical fiber
Effective area A_{e ff}The focus is on increasing
ing.

At present, various zero-dispersion single mode optical fiber networks, which have a wavelength dispersion of several ps / nm / km in the used wavelength band, are slightly shifted from the used wavelength band like the 1.3 μm zero-dispersion single mode optical fiber network. NZ-DSF has already been installed all over the world and is expected to be installed in the future. These optical fibers have + wavelength dispersion in the 1.55 μm wavelength band.
1.3μm because it is suppressed to around 4ps / nm / km
The distance over which dispersion compensation is unnecessary can be made longer than that of a zero-dispersion single-mode optical fiber. When transmitting using this optical fiber, 200-
A transmission line length of about 300 km is the limit due to residual dispersion. Therefore, as with the dispersion compensating optical fiber for the 1.3 μm band zero dispersion single mode optical fiber, this NZ-D
Development of a dispersion compensating optical fiber for compensating for chromatic dispersion of SF is also in progress. This dispersion-compensating optical fiber has a large negative dispersion and dispersion slope in the wavelength band used by controlling the refractive index distribution, and by connecting it to the optical fiber for transmission at an appropriate length, a single-mode optical fiber for transmission can be obtained. It is possible to cancel out the positive dispersion generated in (1) in a wide wavelength range, and it becomes possible to perform high speed communication.

The NZ-DSF is a standard single mode.
Compared with optical fiber, the value of chromatic dispersion is smaller in the wavelength band used.
Therefore, the ratio of the dispersion slope to the chromatic dispersion to be compensated
(Relative dispersion slop
e, hereinafter abbreviated as "RDS". ) Is large, so manufacturing
Is very difficult. 1.3μm band zero dispersion single mode
In case of optical fiber, wavelength dispersion is 1.55μm band
About +17 ps / nm / km, dispersion slope is about +0.0
58 ps / nm^TwoSince it has a dispersion characteristic of / km,
This RDS is 0.0034 nm^-1Before and after. Only
However, in NZ-DSF, chromatic dispersion is about +4.5 ps / n
m / km, dispersion slope is about + 0.045ps / nm^Two
/ Km to + 0.090ps / nm ^Two/ Km dispersion characteristics
Required RDS is 0.01nm^-1~
0.02 nm^-1And as a dispersion compensation fiber
, It is necessary to increase the absolute value of the dispersion slope. Special
NZ-D, which has a large effective area among NZ-DSFs
The wavelength dispersion of SF is about +4.5 ps / nm / km,
Rope is about + 0.090ps / nm^Two/ Km dispersion characteristics
, The required RDS is 1.3 μm band zero dispersion.
0.02, which is about 6 times the RDS of single mode optical fiber
nm^-1As a dispersion-compensating fiber,
It is necessary to increase the absolute value of the dispersion slope of the line.

To date, there have been some reports on this type of dispersion compensating optical fiber. For example, chromatic dispersion of 0 ps / nm / km to -40 ps / nm
The dispersion slope is -0.1 ps / nm ^{2 in} the range of / km.
An invention regarding an optical fiber in the range of / km to −0.5 ps / nm ² / km is disclosed (for example, refer to Patent Document 1). Furthermore, wavelength dispersion is -40 ps / nm
In the range of / km or less, the ratio of chromatic dispersion and dispersion slope is 5
An invention regarding an optical fiber having a range of 0 nm to 230 nm is disclosed (for example, refer to Patent Document 2). In patent document 3, -0.8 ps / nm < ² > / km--0.
Dispersion slope of 5 ps / nm ² / km and -130 ps
The invention of an optical fiber having a chromatic dispersion of / nm / km to -90 ps / nm / km is disclosed. In Patent Document 4, W having an average dispersion slope of −0.6 ps / nm ² / km or less and a chromatic dispersion of −6 ps / nm / km or less W
The invention of a dispersion slope compensating optical fiber having a mold profile is disclosed.

[0007]

[Patent Document 1] US Pat. No. 5,838,867 or JP-A-10-39155.

[Patent Document 2] US Pat. No. 6,263,138

[Patent Document 3] Japanese Patent Laid-Open No. 2000-162462

[Patent Document 4] Japanese Patent Laid-Open No. 2000-47048

[0008]

However, in these inventions, although the range of RDS is preferably set to a range larger than 0.007 nm ^-1 , the chromatic dispersion is -50 ps / nm / km to -130 ps / n
the range of m / miles, RDS is 0.007Nm ^- how to obtain a large optical fiber than ^1, and the chromatic dispersion -2
The range of 0 ps / nm / km to -140 ps / nm / km and the RDS of 0.016 nm ^-1 to 0.024 nm
There is no indication of how to obtain an optical fiber in the ^-1 range. The present invention has been made to solve such a problem, and has a large absolute value of the dispersion slope on the negative side while increasing the absolute value of chromatic dispersion more than in the past, and is large for dispersion compensation. It is an object of the present invention to provide a dispersion compensating optical fiber having a sufficient dispersion slope characteristic even for NZ-DSF requiring RDS, and to provide a dispersion compensating optical fiber module that can be downsized.

[0009]

In order to solve the above problems, the invention according to claim 1 is provided with at least a central core having a refractive index higher than that of the clad, and provided on the outer periphery of the central core. A depressed core having a refractive index smaller than that of the clad, a ring core provided on the outer periphery of the depressed core and having a refractive index higher than that of the clad, and a clad provided on the outer periphery of the ring core are provided. 0.5 μm to 9.5
μm, the ratio of the depressed core radius to the central core radius is 2.0 to 4.0, the ratio of the ring core radius to the depressed core radius is 1.1 to 2.0, and the relative refractive index difference of the central core to the cladding is +1. 00%-+ 1.90
%, The relative refractive index difference of the depressed core with respect to the clad is −
0.60% to -1.00%, the relative refractive index difference of the ring core with respect to the cladding is + 0.20% to + 1.00%,
Chromatic dispersion of -50 ps / nm at at least one wavelength selected from 1.53 μm to 1.63 μm
/ Km~-150ps / nm / km in the range of, dispersion slope -0.25ps ^/ nm 2 /km~-3.0p
It is in the range of s / nm ² / km, and the ratio of the dispersion slope to the wavelength dispersion is 0.005 nm ^{−1 to} 0.020 nm.
^The dispersion compensating optical fiber is characterized by having a cutoff wavelength in the range of ⁻¹ and capable of substantially propagating a single mode in its used length when it is wound and used.

According to a second aspect of the present invention, at least a central core having a refractive index higher than that of the cladding, a depressed core provided on the outer periphery of the central core and having a refractive index lower than that of the cladding, and the depressed core. A ring core having a refractive index larger than that of the clad and provided on the outer circumference of the clad, and a clad provided on the outer circumference of the ring core.
9.5 μm, the ratio of the depressed core radius to the central core radius is 2.0 to 3.5, the ratio of the ring core radius to the depressed core radius is 1.1 to 1.5, and the relative refractive index difference of the central core to the cladding is + 1.30% to +1.
80%, the relative refractive index difference of the depressed core with respect to the clad is −0.68% to −0.75%, the relative refractive index difference of the ring core with respect to the clad is + 0.3% to + 0.6%,
Chromatic dispersion of -50 ps / nm at at least one wavelength selected from 1.53 μm to 1.63 μm
/ Km~-100ps / nm / km in the range of, dispersion slope -0.25ps ^/ nm 2 /km~-2.0p
It is in the range of s / nm ² / km, and the ratio of the dispersion slope to the wavelength dispersion is 0.005 nm ^{−1 to} 0.020 nm.
^The dispersion compensating optical fiber is characterized by having a cutoff wavelength in the range of ⁻¹ and capable of substantially propagating a single mode in its used length when it is wound and used.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the dispersion compensating optical fiber described above, the transmission loss is 0.5.
The bending loss at a diameter of 20 mm at the longest wavelength of the wavelength band selected from 1.53 μm to 1.63 μm is 100 dB / m or less. The invention according to claim 4 is the dispersion compensating optical fiber according to claim 1 or 2, wherein the transmission loss is 0.5 dB / k.
The bending loss at a diameter of 20 mm at the longest wavelength of the wavelength band selected from 1.53 μm to 1.63 μm is 20 dB / m or less. According to a fifth aspect of the present invention, in the dispersion compensating optical fiber according to the second aspect, at least one wavelength selected from 1.53 μm to 1.63 μm, the ratio of the dispersion slope to the chromatic dispersion is 0.010 nm ^{−. 1 to} 0.020n
m ⁻¹ , has a cutoff wavelength capable of substantially single mode propagation, and has a transmission loss of 0.5 dB / km.
The bending loss at the longest wavelength in the wavelength band selected from 1.53 μm to 1.63 μm is 20 mm at a diameter of 20 mm.
It is characterized by being 0 dB / m or less.

The present invention as defined in claim 6 is any one of claims 1 to 5.
In the dispersion compensating optical fiber described in any one of 1 to 3, a layer having a refractive index lower than that of the clad is provided between the ring core and the clad. The invention according to claim 7 is a dispersion-compensating optical fiber module using the dispersion-compensating optical fiber according to any one of claims 1 to 6.

According to an eighth aspect of the present invention, at least a central core having a refractive index higher than that of the cladding, a depressed core provided on the outer periphery of the central core and having a refractive index lower than that of the cladding, and the depressed core. And a clad provided on the outer periphery of the ring core, the ring core having a radius of 6.7 μm to
The ratio of the depressed core radius to the central core radius is 2.0 to 3.0, the ratio of the ring core radius to the depressed core radius is 1.3 to 2.0, and the relative refractive index difference of the central core to the cladding is 10.7 μm. + 1.00% to +
1.80%, the relative refractive index difference of the depressed core with respect to the clad is -1.20% to -1.50%, and the relative refractive index difference of the ring core with respect to the clad is + 0.20% to + 0.50%.
And at least one or more wavelengths selected from 1.53 μm to 1.57 μm, the chromatic dispersion is −20 p.
s / nm / km to -140 ps / nm / km, and the ratio of dispersion slope to chromatic dispersion is 0.016 nm
A dispersion-compensating optical fiber having a cutoff wavelength in the range of ^{−1 to} 0.024 nm ⁻¹ and capable of substantially propagating in a single mode when used by being wound.

According to a ninth aspect of the present invention, at least a central core having a refractive index higher than that of the clad, a depressed core provided on the outer periphery of the central core and having a refractive index lower than that of the clad, and the depressed core. And a clad provided on the outer periphery of the ring core, the ring core having a radius of 6.7 μm to
The ratio of the depressed core radius to the central core radius is 2.0 to 3.0, the ratio of the ring core radius to the depressed core radius is 1.4 to 2.0, and the relative refractive index difference of the central core to the cladding is 8.7 μm. + 1.40% to +1.
80%, the relative refractive index difference of the depressed core to the clad is −1.20% to −1.50%, the relative refractive index difference of the ring core to the clad is + 0.20% to + 0.50%, and 1.53 μm to 1 Chromatic dispersion of -40 ps / at least at one or more wavelengths selected from .57 μm
nm / km to -90 ps / nm / km, and the ratio of dispersion slope to chromatic dispersion is 0.016 nm ^-1 to
It is a dispersion compensating optical fiber having a cutoff wavelength in the range of 0.024 nm ⁻¹ and capable of substantially propagating a single mode in its used length when being wound and used. As a result, the same action and effect as those of the invention described in claim 8 can be obtained.

According to a tenth aspect of the present invention, in the dispersion compensating optical fiber according to the eighth or ninth aspect, the transmission loss is 0.
7 dB / km or less, 1.53 μm to 1.57 μm
20mm diameter at the longest wavelength of the wavelength band selected from
The bending loss at 40 dB / m is less than 40 dB / m. The invention described in claim 11 is the dispersion compensating optical fiber according to claim 8 or 9, wherein the transmission loss is 0.7 dB /
The bending loss at a diameter of 20 mm at the longest wavelength of the wavelength band selected from 1.53 μm to 1.57 μm is 10 dB / m or less.

A twelfth aspect of the present invention is a dispersion compensating optical fiber module using the dispersion compensating optical fiber according to any one of the eighth to eleventh aspects.
According to a thirteenth aspect of the present invention, in the dispersion compensating optical fiber module according to the twelfth aspect, the dispersion compensating optical fiber according to any one of the eighth to eleventh aspects is wound around a reel having a barrel diameter of 100 mm or less, and the dispersion compensating optical fiber is wound. 1.
3 μm band zero dispersion single mode optical fiber or 1.5
A 5 μm band non-zero dispersion shift optical fiber is connected.

According to a fourteenth aspect of the present invention, in the dispersion compensating optical fiber module according to the twelfth aspect, the dispersion compensating optical fiber according to any one of the eighth to eleventh aspects is wound on a reel having a barrel diameter of 100 mm or less and the dispersion is performed. An intermediate optical fiber for adjusting the mode field diameter to reduce the connection loss is connected to both ends of the compensation optical fiber, and a 1.3 μm band zero dispersion single mode optical fiber or a 1.55 μm band non-optical fiber is connected to both ends of the intermediate optical fiber. A zero dispersion shifted optical fiber is connected. As a result, the mode field diameter of the connected optical fiber can be adjusted, so that it is possible to realize a dispersion compensating optical fiber module that can reduce the connection loss and can be downsized.

According to a fifteenth aspect of the present invention, in the dispersion compensating optical fiber module according to the fourteenth aspect, the dispersion compensating optical fiber and the 1.3 μm band zero dispersion single mode optical fiber are connected via the intermediate optical fiber. When using the dispersion compensating optical fiber and the 1.55 μm
When the band non-zero dispersion shift optical fiber is connected through the intermediate optical fiber, the intermediate optical fiber is heated and connected to this connection portion while applying tension along the longitudinal direction of the optical fiber. The total of connection loss at both ends of is 1
It is characterized in that it is set to be not more than dB. Claim 1
According to a sixth aspect of the present invention, in the dispersion compensating optical fiber module according to any one of the thirteenth to fifteenth aspects, the dispersion compensating optical fiber is wound around the reel with a winding tension of 20 g or more and 50 g or less. . As a result, it is possible to realize a dispersion compensating optical fiber module that can prevent winding collapse and prevent loss and deterioration of polarization dispersion characteristics.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
FIG. 1 shows an example of the refractive index distribution of the dispersion compensating optical fiber of the present invention. 1 (a), 1 (b), and 1 (c), reference numeral 1 is a central core, reference numeral 2 is a depressed core provided on the outer periphery of the central core 1, and reference numeral 3 is an outer periphery of the depressed core 2. A ring core provided on the upper side, reference numeral 4 is a clad provided on the outer periphery of the ring core 3. In the figure, the radius of the central core 1 is a, the radius of the depressed core 2 is b, the radius of the ring core 3 is c, the relative refractive index difference of the central core 1 with respect to the clad 4 is Δ1, and the relative refractive index difference of the depressed core 2 with respect to the clad 4 is Δ1. Is Δ2 and the relative refractive index difference of the ring core 3 with respect to the cladding 4 is Δ3. The central core 1 has a refractive index higher than that of the cladding 4,
The depressed core 2 has a refractive index lower than that of the cladding 4, and the ring core 3 has a refractive index higher than that of the cladding 4. FIG. 1C shows a layer 5 having a lower refractive index than the cladding 4 between the ring core 3 and the cladding 4.
Is an example of the refractive index distribution in which the radius of this layer 5 is d,
The relative refractive index difference of this layer 5 with respect to the cladding 4 is Δ4.

The first example of the dispersion compensating optical fiber of the present invention has a radius c of the ring core 3 of 6.5 μm to 9.5 μm,
The ratio b / a of the depressed core radius to the central core radius is 2.0 to 4.0, the ratio c / b of the ring core radius to the depressed core radius is 1.1 to 2.0, and the relative refractive index of the central core 1 to the clad 4 is set. Difference Δ1 is + 1.00% to +
1.90%, the relative refractive index difference Δ2 of the depressed core 2 with respect to the cladding 4 is −0.60% to −1.00%, and the relative refractive index difference Δ3 of the ring core 3 with respect to the cladding 4 is +0.20.
% To + 1.00%. The ratio d / c of the radius d of the layer 5 between the ring core 3 and the cladding 4 to the ring core radius c is preferably 1.3 to 1.8, and the relative refractive index of this layer 5 to the cladding 4 is The difference Δ4 is preferably −0.04% to −0.20%.

By taking such a refractive index distribution,
Chromatic dispersion of -50 ps / nm at at least one wavelength selected from 1.53 μm to 1.63 μm
/ Km~-150ps / nm / km in the range of, dispersion slope -0.25ps ^/ nm 2 /km~-3.0p
s / nm ² / km range, RDS 0.005n
m is in the range of ^{-1 ~0.020nm -1,} substantially can be produced a dispersion compensating optical fiber having a single-mode propagation Cutoff wavelength.

Next, the second dispersion compensating optical fiber according to the present invention will be described.
In the example, the radius c of the ring core 3 is 6.5 μm to 9.5 μm.
m, ratio of depressed core radius to central core radius b /
a is 2.0 to 3.5, the ratio c / b of the ring core radius to the depressed core radius is 1.1 to 1.5, and the relative refractive index difference Δ1 of the central core 1 with respect to the cladding 4 is + 1.30%.
~ + 1.80%, Depressed core 2 for clad 4
Relative refractive index difference Δ2 of −0.68% to −0.75%, and relative refractive index difference Δ3 of the ring core 3 to the cladding 4 is +0.
It is formed as 3% to + 0.6%. The ratio d / c of the radius d of the layer 5 between the ring core 3 and the cladding 4 to the ring core radius c is preferably 1.3 to 1.8, and the relative refractive index of this layer 5 to the cladding 4 is The difference Δ4 is preferably −0.04% to −0.20%.

By taking such a refractive index distribution,
Chromatic dispersion of -50 ps / nm at at least one wavelength selected from 1.53 μm to 1.63 μm
/ Km~-100ps / nm / km in the range of, dispersion slope -0.25ps ^/ nm 2 /km~-2.0p
s / nm ² / km range, RDS 0.005n
A dispersion compensating optical fiber having a cutoff wavelength capable of substantially single mode propagation is produced in the range of m ^{−1 to} 0.020 nm ⁻¹ , more preferably in the range of 0.010 nm ^{−1 to} 0.020 nm ^−1. can do.

In a third example of the dispersion compensating optical fiber of the present invention, the radius c of the ring core 3 is 6.7 μm to 10.7 μm.
m, ratio of depressed core radius to central core radius b /
a is 2.0 to 3.0, the ratio c / b of the ring core radius to the depressed core radius is 1.3 to 2.0, and the relative refractive index difference Δ1 of the central core 1 to the cladding 4 is + 1.00%.
~ + 1.80%, Depressed core 2 for clad 4
Relative refractive index difference Δ2 of −1.20% to −1.50%, and relative refractive index difference Δ3 of the ring core 3 to the cladding 4 is +0.
It is formed as 20% to + 0.50%. The ratio d / c of the radius d of the layer 5 between the ring core 3 and the cladding 4 to the ring core radius c is preferably 1.3 to 2.0, and the relative refractive index of this layer 5 to the cladding 4 is The difference Δ4 is preferably −0.04% to −0.12%. Even if all of these numerical ranges are satisfied, it is not always possible to obtain a dispersion compensating optical fiber having the following characteristics. That is, it is possible to obtain an appropriate combination of a plurality of structural parameters that obtains the following characteristics only by performing trial and error.

Taking the refractive index profile of this appropriate combination
Selected from 1.53μm to 1.57μm.
At least one wavelength has chromatic dispersion of -20p
s / nm / km to -140 ps / nm / km
RDS is 0.016nm ^-1~ 0.024nm^-1
The range is within the range of
In addition, the
Of a dispersion compensating optical fiber having a cutoff wavelength
You can

Next, the fourth dispersion compensating optical fiber of the present invention will be described.
In the above example, the radius c of the ring core 3 is 6.7 μm to 8.7 μm.
m, ratio of depressed core radius to central core radius b /
a is 2.0 to 3.0, the ratio c / b of the ring core radius to the depressed core radius is 1.4 to 2.0, and the relative refractive index difference Δ1 of the central core 1 with respect to the cladding 4 is + 1.30%.
~ + 1.60%, Depressed core 2 for clad 4
Relative refractive index difference Δ2 of −1.20% to −1.50%, and relative refractive index difference Δ3 of the ring core 3 to the cladding 4 is +0.
It is formed as 2% to + 0.4%. The ratio d / c of the radius d of the layer 5 between the ring core 3 and the cladding 4 to the ring core radius c is preferably 1.3 to 2.0, and the relative refractive index of this layer 5 to the cladding 4 is The difference Δ4 is preferably −0.04% to −0.12%. Even if all of these numerical ranges are satisfied, it is not always possible to obtain a dispersion compensating optical fiber having the following characteristics. That is, it is possible to obtain an appropriate combination of a plurality of structural parameters that obtains the following characteristics only by performing trial and error.

By taking the refractive index distribution of this suitable combination, the chromatic dispersion is −40 p at least at one or more wavelengths selected from 1.53 μm to 1.57 μm.
s / nm / km~-90ps / nm / km in the range of, RDS is 0.016nm ^{- 1} ~0.024nm ^-1
When used by being wound around the range, reel, etc., it is possible to manufacture a dispersion compensating optical fiber having a cut-off wavelength capable of substantially single mode propagation.

Next, an example of the dispersion compensating optical fiber module of the present invention will be described. In the dispersion compensating optical fiber module of this example, the above-mentioned dispersion compensating optical fiber may have a larger barrel diameter, but for example, it is wound on a reel having a barrel diameter of 100 mm or less, and 1.3 μ at both ends of the dispersion compensating optical fiber.
m-band zero dispersion single mode optical fiber or NZ-DS
F is connected and formed. Also, an intermediate optical fiber may be connected to both ends of this dispersion compensating optical fiber, and a 1.3 μm band zero dispersion single mode optical fiber or NZ-DSF may be connected to both ends of this intermediate optical fiber. The intermediate optical fiber used here is for adjusting the mode field diameter of the connected optical fiber in order to reduce the connection loss that occurs when connecting the optical fibers. Close to the fiber,
It is an optical fiber that can be connected to a dispersion compensating optical fiber with low loss by low heating connection, and whose bending loss does not deteriorate even with high heating connection.

Thus, the dispersion compensating optical fiber and the 1.3 μm band zero dispersion single mode optical fiber are connected via the intermediate optical fiber, or the dispersion compensating optical fiber and the NZ are connected.
-When connecting with the DSF, it is preferable to adjust the heating temperature and time at each connection point and apply heat to the connection portion while applying tension along the longitudinal direction of the optical fiber. . This makes it possible to reduce the total connection loss at both ends of the intermediate optical fiber to 1 dB or less. Further, in the above dispersion compensation optical fiber module,
The winding tension when wound on the reel is preferably 20 g or more and 50 g or less. This is because if the weight is less than 20 g, rolling collapse occurs due to vibration or shock, and stable characteristics cannot be obtained, and if the weight exceeds 50 g, lateral pressure at the time of winding causes deterioration of the loss and polarization dispersion characteristics. Specific examples will be shown below.

(Example 1) VAD method, MCVD method, PC
The refractive index distribution shown in FIG. 1 (c) is obtained by a known method such as VD method, and Δ1, Δ2, Δ3, Δ4, b / a, c /
Four types of dispersion-compensating optical fibers A, B, C, and D were manufactured so that b and d / c had the values shown in Table 1. As can be seen from Δ4 = 0, the dispersion compensating optical fiber D does not have the layer 5 between the ring core 3 and the clad 4, and therefore has the refractive index distribution shown in FIG. .
Table 1 shows the optical characteristics of this dispersion compensating optical fiber.

[0031]

[Table 1]

The RDS of these dispersion compensating optical fibers is
In the optical fiber A 0.0088nm ^{- 1,} 0.010nm ^-1 in an optical fiber B, 0.016 nm in the optical fiber C
⁻¹ , and the optical fiber D has a thickness of 0.0085 nm ⁻¹ . These dispersion-compensating optical fibers have a large absolute value of chromatic dispersion, but have a large RDS as compared with conventional dispersion-compensating optical fibers. Therefore, the residual chromatic dispersion of the NZ-DSF forming the optical transmission line can be compensated in a wide wavelength range, and the transmission speed can be improved. The transmission loss of each of the optical fibers A to D is 0.5 dB / km or less. Furthermore, 1.
It is possible to set the bending loss at a diameter of 20 mm to 100 dB / m or less at the longest wavelength in the wavelength band selected from 53 μm to 1.63 μm. Particularly, for the optical fiber A and the optical fiber D, the diameter is 20 mm. Bending loss of 20d
It can be B / m or less.

(Example 2) VAD method, MCVD method, PC
The refractive index distribution shown in FIG. 1 (c) is obtained by a known method such as VD method, and Δ1, Δ2, Δ3, Δ4, b / a, c /
Two types of dispersion-compensating optical fibers E and F were manufactured so that b and d / c had the values shown in Table 2. Table 2 shows the optical characteristics of this dispersion compensating optical fiber.

[0034]

[Table 2]

The RDS of these dispersion compensating optical fibers is
0.007Nm ^-1 in the optical fiber E, which is 0.011 nm ^-1 in the optical fiber F. These dispersion-compensating optical fibers have a large absolute value of chromatic dispersion, but have a large RDS as compared with conventional dispersion-compensating optical fibers. Therefore, the residual chromatic dispersion of the NZ-DSF forming the optical transmission line can be compensated in a wide wavelength range, and the transmission speed can be improved. The transmission loss of both the optical fibers E and F is 0.5 dB.
/ Km or less. Furthermore, 1.53 μm to 1.63 μ
At the longest wavelength in the wavelength band selected from m, the bending loss at a diameter of 20 mm can be 20 dB / m or less.

According to the dispersion compensating optical fiber of this example, the absolute value of the chromatic dispersion is large, but the absolute value of the dispersion slope can be increased.
It is possible to manufacture a dispersion compensating optical fiber
A dispersion-compensating optical fiber having a high dispersion slope compensation rate can be realized even for an NZ-DSF having a chromatic dispersion of several ps / nm / km in the wavelength band of 1.55 μm.
As a result, the residual chromatic dispersion of the NZ-DSF forming the optical transmission line can be compensated for in a wide wavelength range, and the transmission speed can be improved. Further, according to the present invention, it is possible to realize a dispersion compensating optical fiber which has a low loss and does not cause an increase in loss even when wound on a small reel. Furthermore, by making a dispersion compensating optical fiber module using this dispersion compensating optical fiber,
A dispersion compensating optical fiber module that can be miniaturized can be realized.

(Example 3) VAD method, MCVD method, PC
The refractive index distribution shown in FIG. 1 (c) is obtained by a known method such as VD method, and Δ1, Δ2, Δ3, Δ4, b / a, c /
Five types of dispersion-compensating optical fibers G, H, I, J, and K were manufactured so that b and d / c had the values shown in Table 3. The dispersion-compensating optical fiber D has a layer 5 between the ring core 3 and the clad 4, as can be seen from Δ4 = 0.
Is not provided, it has the refractive index distribution shown in FIG. Table 3 shows the optical characteristics of this dispersion compensating optical fiber.

[0038]

[Table 3]

The RDS of these dispersion compensating optical fibers is
In the optical fiber G 0.0201nm ^{- 1,} 0.0197nm ^-1 in an optical fiber H, 0.0191n optical fiber I
m ^{- 1,} 0.0190nm ^-1 in an optical fiber J, 0.0191Nm optical fiber K ^- a ^1, all 0.0
In the range of 16nm ^-1 ~0.024nm ^-1. These dispersion-compensating optical fibers have a large RDS as compared with the conventional dispersion-compensating optical fibers while maintaining the absolute value of chromatic dispersion at a large value. Therefore, the residual chromatic dispersion of the NZ-DSF forming the optical transmission line can be compensated in a wide wavelength range, and the transmission speed can be improved. The transmission loss of each of the optical fibers G to K is 0.7 dB / km or less. further,
At the longest wavelength of the wavelength band selected from 1.53 μm to 1.57 μm, the bending loss at a bending diameter of 20 mm is 40 dB /
m or less, in particular, the optical fiber G,
For H, I, and J, the bending loss at a diameter of 20 mm is 1
It can be set to 0 dB / m or less.

Dispersion compensating optical fibers G to K shown in Table 3
Is wound on a small reel having a barrel diameter of 80 mm with a winding tension of 40 g to produce a small coil, and an intermediate optical fiber is connected to both ends of the small coil to reduce the connection loss.
NZ-DSF dispersion-compensating optical fiber modules G to K were produced in which m-band zero-dispersion single-mode optical fibers were connected and the input and output at both ends were 1.3 μm band zero-dispersion single-mode optical fibers. The dispersion compensating optical fiber modules G to K are all 100 km long NZ-DSFs.
Is a dispersion compensating optical fiber module for dispersion compensating. Table 4 shows the optical characteristics of these dispersion-compensating optical fiber modules.

[0041]

[Table 4]

The RDS of these dispersion compensating optical fiber modules are all 0.016 nm ^{−1 to} 0.024 nm.
^The dispersion-compensating optical fiber module is in the range of ⁻¹ , and there is no increase in loss due to entrainment and low loss. Therefore, the residual chromatic dispersion of NZ-DSF in the optical transmission line can be compensated for in a wide wavelength range, and the transmission speed can be improved.

According to the dispersion compensating optical fiber of this example, the RDS is less than 0, even though the absolute value of chromatic dispersion is large.
The dispersion-compensating optical fiber can be manufactured in a range of 016 nm ^{−1 to} 0.024 nm ⁻¹ , and a large RDS can be obtained, and the dispersion-compensating optical fiber has a wavelength of 1.55 μm and +4.5.
Chromatic dispersion of ps / nm / km and + 0.09ps / nm
It is possible to realize a dispersion compensating optical fiber having a high dispersion slope compensation rate even for an NZ-DSF having a dispersion slope of ² / km. This makes it possible to compensate the residual chromatic dispersion of the NZ-DSF forming the optical transmission line in a wide wavelength range, improve the transmission speed, and increase the transmission speed to 40 Gb /
It is possible to construct a high-speed optical transmission line such as s.

Further, according to the dispersion compensating optical fiber of this example, it is possible to realize a dispersion compensating optical fiber which has a low loss and which does not cause an increase in loss even when wound on a small reel. Further, by connecting an intermediate optical fiber to both ends of the dispersion compensating optical fiber wound on the reel, and connecting a 1.3 μm band zero dispersion single mode optical fiber or NZ-DSF to both ends of the intermediate optical fiber, respectively. Since it is possible to make a connection with the mode field diameter adjusted at the connection point, it is possible to realize a dispersion compensating optical fiber module capable of reducing connection loss and downsizing.

Further, the dispersion compensating optical fiber is connected to the 1.3 μm band zero dispersion single mode optical fiber via the intermediate optical fiber, or the dispersion compensating optical fiber and the NZ-D are connected.
When connecting to the SF, the total of the connection loss at both ends of the intermediate optical fiber is set to 1 by heating the connection while applying tension to the connection along the longitudinal direction of the optical fiber.
The value can be set to dB or less, and a low-loss dispersion compensation optical fiber module can be realized. Also, the winding tension when winding the dispersion compensating optical fiber around the reel is 20 g.
By setting the weight to 50 g or more, it is possible to realize a dispersion-compensating optical fiber module capable of preventing winding collapse even against vibration and shock, and preventing loss and deterioration of polarization dispersion characteristics. .

[0046]

As described above, according to the present invention,
Even though the absolute value of chromatic dispersion is large, the absolute value of dispersion slope can be increased, so that a large RD
A dispersion compensating optical fiber capable of obtaining S can be produced, and a dispersion compensating light having a high dispersion slope compensation rate can be obtained even for an NZ-DSF having a chromatic dispersion of several ps / nm / km in a wavelength of 1.55 μm. Fibers can be realized. As a result, the residual chromatic dispersion of the NZ-DSF forming the optical transmission line can be compensated for in a wide wavelength range, and the transmission speed can be improved. Further, according to the present invention, it is possible to realize a dispersion compensating optical fiber which has a low loss and does not cause an increase in loss even when wound on a small reel. Furthermore, by manufacturing a dispersion compensating optical fiber module using this dispersion compensating optical fiber, it is possible to realize a dispersion compensating optical fiber module that can be downsized.

Further, according to the present invention, the ring core radius is
6.7 μm to 10.7 μm, the data for the central core radius
The ratio of the radius of the pressed core is 2.0 to 3.0,
A ratio of ring core radius to radius is 1.3 to 2.0
And the relative refractive index difference of the central core with respect to the cladding is +1.
00%-+ 1.80%, Depressed to the clad
A relative refractive index difference of -1.20% to -1.50%,
The relative refractive index difference of the ring core with respect to + is + 0.20% to +
Fabrication of dispersion compensating optical fiber with 0.50%
Select from 1.53μm to 1.57μm
At least one or more wavelengths
-20 ps / nm / km to -140 ps / nm / km
Within the range, the ratio of dispersion slope to chromatic dispersion is 0.0
16 nm ^-1~ 0.024nm^-1Is in the range of
When used in combination, it is practically single-mode due to its length.
Can have a cut-off wavelength that can
Large RDS with a large absolute value of dispersion
Obtainable.

Therefore, in the wavelength band of 1.55 μm, about +4.
Wavelength dispersion of 5 ps / nm / km and about +0.09 ps /
A dispersion-compensating optical fiber having a high dispersion slope compensation rate can be realized even for NZ-DSF having a dispersion slope of nm ² / km. This makes it possible to compensate the residual chromatic dispersion of the NZ-DSF forming the optical transmission line in a wide wavelength range, improve the transmission rate, and
It is possible to construct a high-speed optical transmission line such as b / s. Further, it is possible to realize a dispersion compensating optical fiber which has a low loss and does not cause an increase in loss even when wound around a small reel.

Such an effect is obtained when the ring core radius is 6.
7 μm to 8.7 μm, the ratio of the depressed core radius to the central core radius is 2.0 to 3.0, the ratio of the ring core radius to the depressed core radius is 1.4 to 2.0,
The relative refractive index difference of the central core to the cladding is + 1.40%
˜ + 1.80%, the relative refractive index difference of the depressed core to the cladding is −1.20% to −1.50%, and the relative refractive index difference of the ring core to the cladding is + 0.20% to +0.5.
0%, and at least one or more wavelengths selected from 1.53 μm to 1.57 μm, the chromatic dispersion is −4.
It is in the range of 0 ps / nm / km to -90 ps / nm / km, and the ratio of dispersion slope to chromatic dispersion is 0.016 nm.
It can also be obtained by being a dispersion compensating optical fiber having a cutoff wavelength in the range of ^{−1 to} 0.024 nm ⁻¹ and capable of substantially propagating a single mode when used while being wound.

Further, according to the present invention, an intermediate optical fiber is connected to both ends of the dispersion compensating optical fiber wound on the reel, and 1.3 μm band zero dispersion single mode optical fiber or NZ-DSF is connected to both ends of the intermediate optical fiber. Since the connection can be made by adjusting the mode field diameter at each connection point, it is possible to realize a dispersion compensating optical fiber module which can reduce the connection loss and can be downsized. Further, the dispersion compensating optical fiber and the 1.3 μm band zero dispersion single mode optical fiber are connected via an intermediate optical fiber, or the dispersion compensating optical fiber and the NZ-DS are connected.
When connecting to F, the total of the connection loss at both ends of the intermediate optical fiber is 1d by heating and connecting to this connection portion while applying tension along the longitudinal direction of the optical fiber.
It can be B or less, and a low-loss dispersion-compensating optical fiber module can be realized. Further, by setting the winding tension when the dispersion compensating optical fiber is wound around the reel to 20 g or more and 50 g or less, it is possible to prevent the collapse of the winding and prevent the loss and the deterioration of the polarization dispersion characteristic. An optical fiber module can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a refractive index distribution of a dispersion compensating optical fiber of the present invention.

[Explanation of symbols]

1 ... Central core, 2 ... Depressed core, 3 ... Ring core, 4 ... Clad, 5 ... Layer between ring core and clad

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takaaki Suzuki             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office (72) Inventor Ryuji Suzuki             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office (72) Inventor Shinichi Nakayama             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office (72) Inventor Kuniharu Himeno             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office F-term (reference) 2H050 AB02Z AC09 AC15 AC29                       AC36 AC38 AC71 AC73 AC76                       AD01                 5K102 AA01 KA02 KA42 PA01 PA04                       PA06

Claims (16)

[Claims] 1. A central core having a refractive index higher than that of the cladding, a depressed core provided on the outer periphery of the central core and having a refractive index lower than the refractive index of the cladding, and a cladding provided on the outer periphery of the depressed core. A ring core having a refractive index larger than that of the core and a clad provided on the outer periphery of the ring core, the ring core radius is 6.5 μm to 9.5 μm, and the ratio of the depressed core radius to the central core radius is 2.0 to 4.
0, the ratio of the ring core radius to the depressed core radius is 1.1 to 2.0, and the relative refractive index difference of the central core with respect to the cladding is + 1.00%.
~ + 1.90%, the relative refractive index difference of the depressed core with respect to the clad is -0.60% to -1.00%, and the relative refractive index difference of the ring core with respect to the clad is + 0.20% to +1.0.
0%, and chromatic dispersion is -50 ps / nm at at least one wavelength selected from 1.53 μm to 1.63 μm.
/ Km~-150ps / nm / km in the range of, dispersion slope -0.25ps ^/ nm 2 /km~-3.0p
It is in the range of s / nm ² / km, and the ratio of the dispersion slope to the wavelength dispersion is 0.005 nm ^{−1 to} 0.020 nm.
A dispersion-compensating optical fiber having a cutoff wavelength in the range of ^-1 and capable of substantially propagating in a single mode at the length of use when wound and used. 2. A central core having a refractive index higher than that of the clad, a depressed core provided on the outer periphery of the central core and having a refractive index lower than the refractive index of the clad, and a cladding provided on the outer periphery of the depressed core. A ring core having a refractive index larger than that of the core and a clad provided on the outer periphery of the ring core, the ring core radius is 6.5 μm to 9.5 μm, and the ratio of the depressed core radius to the central core radius is 2.0 to 3.
5, the ratio of the ring core radius to the depressed core radius is 1.1 to 1.5, and the relative refractive index difference of the central core with respect to the cladding is + 1.30%.
~ + 1.80%, the relative refractive index difference of the depressed core to the cladding is -0.68% to -0.75%, and the relative refractive index difference of the ring core to the cladding is + 0.3% to + 0.6%.
And at least one or more wavelengths selected from 1.53 μm to 1.63 μm, the chromatic dispersion is −50 ps / nm.
/ Km~-100ps / nm / km in the range of, dispersion slope -0.25ps ^/ nm 2 /km~-2.0p
It is in the range of s / nm ² / km, and the ratio of the dispersion slope to the wavelength dispersion is 0.005 nm ^{−1 to} 0.020 nm.
A dispersion-compensating optical fiber having a cutoff wavelength in the range of ^-1 and capable of substantially propagating in a single mode at the length of use when wound and used. 3. The transmission loss is 0.5 dB / km or less, and the bending loss at a diameter of 20 mm is 100 at the longest wavelength of the wavelength band selected from 1.53 μm to 1.63 μm.
It is below dB / m, The claim 1 or 2 characterized by the above-mentioned.
The dispersion-compensating optical fiber described. 4. The transmission loss is 0.5 dB / km or less, and the bending loss at a diameter of 20 mm at the longest wavelength of the wavelength band selected from 1.53 μm to 1.63 μm is 20 d.
The dispersion compensating optical fiber according to claim 1 or 2, characterized in that it is B / m or less. 5. At least one or more wavelengths selected from 1.53Myuemu～1.63Myuemu, the ratio for the wavelength dispersion of the dispersion slope 0.010nm ^{- 1} ~0.0
It has a cutoff wavelength in the range of 20 nm ⁻¹ and can propagate substantially a single mode, and has a transmission loss of 0.5 dB.
/ Km or less, and the bending loss at a diameter of 20 mm at the longest wavelength of the wavelength band selected from 1.53 μm to 1.63 μm is 100 dB / m or less.
The dispersion-compensating optical fiber described. 6. The dispersion compensating optical fiber according to claim 1, wherein a layer having a refractive index lower than that of the clad is provided between the ring core and the clad. 7. A dispersion compensating optical fiber module using the dispersion compensating optical fiber according to any one of claims 1 to 6. 8. A central core having a refractive index higher than that of the clad, a depressed core provided on the outer periphery of the central core and having a refractive index lower than the refractive index of the clad, and a cladding provided on the outer periphery of the depressed core. A ring core having a refractive index larger than that of the core and a clad provided on the outer periphery of the ring core, the ring core radius is 6.7 μm to 10.7 μm, and the ratio of the depressed core radius to the central core radius is 2.0 to 3.
0, the ratio of the ring core radius to the depressed core radius is 1.3 to 2.0, and the relative refractive index difference of the central core with respect to the cladding is + 1.00%.
˜ + 1.80%, the relative refractive index difference of the depressed core to the cladding is −1.20% to −1.50%, and the relative refractive index difference of the ring core to the cladding is + 0.20% to +0.5.
0%, and chromatic dispersion is -2 at least at one or more wavelengths selected from 1.53 μm to 1.57 μm.
It is in the range of 0 ps / nm / km to -140 ps / nm / km, and the ratio of dispersion slope to chromatic dispersion is 0.016.
nm in the range of ^{-1 ~0.024nm -1,} is wound in substantially in its use length when using dispersed compensating optical fiber characterized by having a single-mode propagation Cutoff wavelength. 9. A central core having a refractive index higher than that of the clad, a depressed core provided on the outer periphery of the central core and having a refractive index lower than the refractive index of the clad, and a cladding provided on the outer periphery of the depressed core. A ring core having a refractive index larger than that of the core and a clad provided on the outer periphery of the ring core, the ring core radius is 6.7 μm to 8.7 μm, and the ratio of the depressed core radius to the central core radius is 2.0 to 3.
0, the ratio of the ring core radius to the depressed core radius is 1.4 to 2.0, and the relative refractive index difference of the central core with respect to the cladding is + 1.40%.
˜ + 1.80%, the relative refractive index difference of the depressed core to the cladding is −1.20% to −1.50%, and the relative refractive index difference of the ring core to the cladding is + 0.20% to +0.5.
0%, and at least one or more wavelengths selected from 1.53 μm to 1.57 μm, the chromatic dispersion is −4.
It is in the range of 0 ps / nm / km to -90 ps / nm / km, and the ratio of dispersion slope to chromatic dispersion is 0.016 nm.
A dispersion-compensating optical fiber having a cutoff wavelength in the range of ^{−1 to} 0.024 nm ⁻¹ and capable of substantially propagating in a single mode when used by being wound. 10. The transmission loss is 0.7 dB / km or less, and the bending loss at a diameter of 20 mm at the longest wavelength of the wavelength band selected from 1.53 μm to 1.57 μm is 40 d.
The dispersion compensating optical fiber according to claim 8 or 9, characterized in that it is B / m or less. 11. The transmission loss is 0.7 dB / km or less, and the bending loss at a diameter of 20 mm at the longest wavelength of the wavelength band selected from 1.53 μm to 1.57 μm is 10 d.
The dispersion compensating optical fiber according to claim 8 or 9, characterized in that it is B / m or less. 12. A dispersion compensating optical fiber module, which uses the dispersion compensating optical fiber according to any one of claims 8 to 11. 13. The dispersion compensating optical fiber according to claim 8, which is wound on a reel having a barrel diameter of 100 mm or less, and 1.3 μm band zero dispersion single mode optical fiber or 1 at both ends of the dispersion compensating optical fiber. 13. The dispersion compensating optical fiber module according to claim 12, further comprising a non-zero dispersion shift optical fiber connected in a 0.55 μm band. 14. The dispersion compensating optical fiber according to claim 8 is wound on a reel having a barrel diameter of 100 mm or less, and a mode field diameter is adjusted at both ends of the dispersion compensating optical fiber to reduce connection loss. 13. A 1.3 μm band zero-dispersion single-mode optical fiber or a 1.55 μm band non-zero-dispersion shifted optical fiber is connected to both ends of this intermediate optical fiber. The dispersion-compensating optical fiber module described. 15. The dispersion compensating optical fiber and the 1.3.
When connecting a μm band zero dispersion single mode optical fiber through the intermediate optical fiber, or connecting the dispersion compensating optical fiber and the 1.55 μm band non-zero dispersion shifted optical fiber through the intermediate optical fiber. At this time, the total connection loss at both ends of the intermediate optical fiber is set to 1 dB or less by heating and connecting to this connection portion while applying tension along the longitudinal direction of the optical fiber. The dispersion compensating optical fiber module according to claim 14, which is characterized in that. 16. The dispersion compensating optical fiber module according to claim 13, wherein the dispersion compensating optical fiber is wound around the reel with a winding tension of 20 g or more and 50 g or less.