JP4962401B2 - Optical fiber ribbon and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical fiber ribbon in which the entire circumference of a plurality of optical fiber cores arranged in parallel is covered with a resin, and a manufacturing method thereof.

  One of the causes of signal degradation when performing high-speed and long-distance transmission with an optical fiber is polarization mode dispersion (PMD). PMD is caused by the group delay difference between two orthogonal polarization modes of an optical signal propagating in an optical fiber.

  As a technique for reducing this PMD, when manufacturing an optical fiber core wire, the optical fiber core wire is rolled by a swinging motion of a swing guide roller to effectively give a predetermined twist, and is a perfect concentric circle. As compared with the case, a technique for equivalently suppressing the polarization dispersion of the optical fiber core wire is known (see, for example, Patent Document 1).

  Further, in an optical fiber core wire including a glass part having a core and a clad and one or more coating layers formed around the glass part, on a cross section perpendicular to the longitudinal direction when the coating is applied There is also known an optical fiber core in which the center of the glass portion and the center of the coating layer are eccentric and the eccentric direction on the cross section is continuously changed in the longitudinal direction (for example, see Patent Document 2). ).

  Also, as an optical fiber ribbon that integrates a plurality of optical fibers, at least two optical fibers are twisted with a non-zero twist per unit length. (For example, see Patent Document 3). In this optical fiber ribbon, each component optical fiber core is formed from the twist amount per unit length of each component optical fiber and the center of the wire connecting the centers of the optical fiber cores positioned at both ends in the cross section. The sum of the products with the distance to the line center is substantially zero.

Further, as a cable accommodating a plurality of optical fiber ribbons, the ratio of the curvature radii R of the optical fiber cores in the same tape core is set to a predetermined value or less, and the difference in PMD is within a predetermined range. What was stored is known (for example, refer to Patent Document 4).
Further, in the cable in which the optical fiber core is housed in the groove portion of the long spacer formed with the spiral groove portion in which the twist direction is periodically reversed, the optical fiber core wire is twisted in the longitudinal direction. It is also known that the PMD is reduced by storing it in the groove in a twisted state by periodically changing (see, for example, Patent Document 5).
In addition, in an optical fiber core cable formed by twisting optical fiber core wires, a technique for reducing PMD by setting the twist rate of the optical fiber core wires to at least partially 0.0104 (rad / mm) or more is also known. (For example, see Patent Document 6).

JP-A-8-295528 Japanese Patent No. 3952949 JP-A-8-43694 JP 2005-257916 A JP 2007-25400 A JP 2002-122762 A

  Even if the PMD is reduced in the state of the optical fiber ribbon as in Patent Documents 1 and 2, when the optical fiber core twisted in one direction is converted into the tape core, Thus, circularly polarized waves are generated and PMD deteriorates. In addition, when the twist amount is increased, peeling occurs at the interface between the glass fiber and the resin, anisotropic strain remains in the glass fiber, and the bending of the optical fiber becomes large, resulting in a decrease in handling properties. Incurs transmission loss.

In Patent Document 3, a twisted optical fiber core is taped so that the twist is offset. However, circular polarization is generated by twisting in one direction, and deterioration of PMD is inevitable. .
In addition, in the techniques of Patent Documents 4 to 6, although it is possible to reduce PMD in a cabled state, it is difficult to reduce PMD of each optical fiber core in the state of the optical fiber ribbon. .

  An object of the present invention is to provide an optical fiber ribbon that can reliably reduce the polarization mode dispersion of each optical fiber, and has good handling properties, and to easily manufacture the optical fiber ribbon. An object of the present invention is to provide a manufacturing method that can be used.

The optical fiber ribbon according to the present invention that can solve the above-mentioned problems is formed by arranging a plurality of optical fiber ribbons in which glass fibers are coated with a resin, and the entire circumference is covered with a taped resin. An optical fiber ribbon that has been made into an optical fiber,
The optical fiber core wire has an elastic torsional strain in which the twisting direction is periodically reversed in the longitudinal direction.

  In the optical fiber ribbon according to the present invention, in the state where the optical fiber core is released from the integration, the glass fiber is eccentric with respect to the resin, and the eccentric position is spiral in the longitudinal direction. It is preferable to have a portion that changes.

  In the optical fiber ribbon according to the present invention, it is preferable that the eccentric rotation speed of the glass fiber is 0.2 times / m or more and 8.0 times / m or less.

  In the optical fiber ribbon according to the present invention, it is preferable that a period of rotation of the glass fiber in the eccentric direction of the optical fiber and a period of reversal of the twist direction of the twist strain are different.

  A method of manufacturing an optical fiber ribbon according to the present invention includes a plurality of optical fiber cores in which glass fibers are coated with a resin, in a state where elastic twisting strains that are periodically reversed in the longitudinal direction are applied. The entire circumference is covered with a taped resin and integrated.

  In the method for manufacturing an optical fiber ribbon according to the present invention, the glass fibers are eccentric in a spiral shape in the longitudinal direction, and the eccentric positions of the glass fibers are aligned in one direction. It is preferable to integrate with a taped resin.

  In the method of manufacturing an optical fiber ribbon according to the present invention, it is preferable that the optical fiber is integrated with the taped resin while twisting by periodically reversing the twist direction.

According to the optical fiber ribbon of the present invention, since the optical fiber has an elastic torsional strain in which the twisting direction is periodically reversed in the longitudinal direction, it does not cause circular polarization. The polarization mode dispersion of each optical fiber core can be reduced. In addition, the bending of the optical fiber core wire can be suppressed as much as possible as compared with a structure in which twisting is continuously applied in one direction, and handling properties can be improved.
According to the method for manufacturing an optical fiber ribbon of the present invention, an optical fiber core having an elastic twist strain in which the twist direction is periodically reversed in the longitudinal direction is taped. An optical fiber ribbon with reduced polarization mode dispersion can be obtained. In addition, the optical fiber ribbon manufactured by this method has excellent handling properties because the bending of the optical fiber is minimized as compared with a structure in which twist is continuously applied in one direction.

Hereinafter, an example of an embodiment of an optical fiber ribbon and a manufacturing method for the same according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an optical fiber core manufacturing apparatus.

  As shown in FIG. 1, the optical fiber core manufacturing apparatus 1 includes a heating furnace 2 that heats the optical fiber preform G on the upstream side of the traveling line of the optical fiber core. The heating furnace 2 includes a heating element 3 as a heater, and a heating region is formed in a space inside the heating furnace 2 by generating heat. A heating area | region here is an area | region which becomes the temperature which can be drawn by softening glass, for example, is an area | region which is 1800 degreeC or more. A gas such as helium or nitrogen is supplied to the heating region of the heating furnace 2.

  The optical fiber preform G is fed into the heating furnace 2 so that the upper part thereof is gripped by the feeding device and the lower end portion thereof is positioned in the heating region of the heating furnace 2. Thus, the lower end side of the optical fiber preform G supplied into the heating furnace 2 is heated and softened in the heating region, and is drawn downward to be reduced in diameter to form a glass fiber G1.

  On the downstream side of the heating furnace 2, for example, a cooling device 7 using a cooling solvent such as helium gas is provided, and the glass fiber G1 is rapidly cooled from several hundred degrees C to near room temperature.

  On the downstream side of the cooling device 7, a die 8 and an ultraviolet irradiation device 9 for applying an ultraviolet curable resin to the glass fiber G1 are provided in this order. Thereby, the glass fiber G1 passes through the die 8 and the ultraviolet irradiation device 9, and becomes an optical fiber core wire G2 in which a resin is applied to the outer peripheral side and a coating layer is formed.

  Thereafter, the direction of the travel line is changed by the direct roller 11, the swing roller 12, and the guide roller 13 provided on the downstream side of the ultraviolet irradiation device 9, and the optical fiber core wire G <b> 2 is taken up by the capstan 14. 15 and a guide roller 16 to be wound around a reel 17.

Next, a method for manufacturing the optical fiber core G2 using the optical fiber core manufacturing apparatus 1 will be described.
First, the optical fiber preform G is introduced into the heating furnace 2, heated by the heating element 3, and drawn downward to obtain a thinned glass fiber G1.
Next, the outer periphery of the glass fiber G1 is coated with an ultraviolet curable resin with a die 8, and further, the ultraviolet curable resin is irradiated with ultraviolet rays and cured with an ultraviolet irradiation device 9, and the optical fiber core wire G2 coated with the resin is coated. And

  Thereafter, the optical fiber core wire G2 is drawn by the capstan 14 through the directly below roller 11, the swinging roller 12 and the guide roller 13 to apply a predetermined tension, and sent to the reel 17 through the dancer roller 15 and the guide roller 16. The reel 17 is wound up.

  As shown in FIG. 2, in the swing roller 12, the rotation shaft X swings alternately in both the left and right directions by the swing mechanism 12a. In the swing roller 12, as shown in FIGS. 2A and 2B, a lateral force is applied to the optical fiber core wire G2 by swinging in one direction, and the circumference of the swing roller 12 is increased. The optical fiber core wire G2 rolls on the surface. This rolling imparts twist to the optical fiber core wire G2.

Subsequently, as shown in FIGS. 2B to 2D, the swing roller 12 swings in the opposite direction, and this time, the optical fiber core wire G <b> 2 faces the opposite direction on the peripheral surface of the swing roller 12. Roll to. Thereby, the twist to a reverse direction is provided to the optical fiber core wire G2. As described above, the oscillating roller 12 is repeatedly and periodically oscillated, whereby twists that are periodically inverted in the longitudinal direction are alternately applied to the optical fiber core wire G2.
Thereby, as shown in FIG. 3, the optical fiber core wire G2 is eccentric in the center with respect to the coating H1 of the glass fiber G1 made of resin, and the eccentric position periodically spirals in the longitudinal direction. It will be in the state which has the changed part.

Next, a method for manufacturing an optical fiber ribbon in which a plurality of optical fibers G2 arranged in parallel are integrated with a resin will be described.
FIG. 4 is a block diagram showing a manufacturing apparatus for manufacturing an optical fiber ribbon.
As shown in FIG. 4, the optical fiber ribbon manufacturing apparatus 40 has a supply 41. In this supply 41, the optical fiber core wire G2 is fed out from the plurality of reels 17 around which the optical fiber core wire G2 is wound, and the fed optical fiber core wire G2 is given a predetermined tension by the dancer roller 43, It is fed out toward the concentrating roller 50 through the turn roller 44.

  The concentrating rollers 50 have groove portions 61 through which the optical fiber cores G2 are passed, and are arranged at a predetermined interval from the number of the optical fiber cores G2.

Below the concentrating roller 50, two coating devices 51 and 52 for coating a plurality of optical fiber core wires G2 are provided. These coating devices 51 and 52 apply an ultraviolet curable resin (taped resin) supplied from the resin storage tank 53 to the optical fiber core G2 and irradiate the applied resin with ultraviolet rays to cure it. And an ultraviolet irradiation device 55.
A turn roller 56 is provided below the covering devices 51 and 52, and a feed capstan 57, a take-up tension control dancer 58, and a take-up device 59 are provided on the side of the turn roller 56.

  The covering devices 51 and 52 may cover a thermoplastic resin instead of an ultraviolet curable resin as a taped resin. The coating devices 51 and 52 in that case are configured to include an extruder for extruding a thermoplastic resin and a cooling device for cooling the extruded resin. Further, only one coating device may be used.

Next, a method for manufacturing an optical fiber ribbon using the above-described optical fiber ribbon manufacturing apparatus 40 will be described.
In the optical fiber ribbon manufacturing apparatus 40, first, a plurality of optical fiber cores G <b> 2 fed out from the supply 41 are arranged at a predetermined interval by the concentrating roller 50.
The plurality of optical fiber cores G2 arranged by the concentrating roller 50 are coated with a taped resin by the two coating devices 51 and 52 to form an integrated optical fiber core optical fiber tape core G3. .

  Thereafter, the direction of the traveling line is changed by the turn roller 56 and the optical fiber tape core G3 is taken up by the delivery capstan 57, and taken up by the take-up device 59 through the take-up tension control dancer 58 and taken up by the take-up device 59. .

FIG. 5 shows the groove 61 of the concentrating roller 50 in which the optical fiber core wires G2 are arranged. As shown in FIG. 5, the groove part 61 has a flat surface part 61a on the inner peripheral side, and has side walls 61b on both sides of the flat surface part 61a. The corners of the flat portion 61a and the side wall 61b are formed in an arc shape.
The flat portion 61a is formed so that its width dimension is about twice the diameter of the optical fiber core wire G2. For example, when the diameter of the optical fiber core wire G2 is 0.25 mm, the width dimension of the flat portion 61a is about 0.5 mm.

  When a predetermined tension (about 1 N) is applied to the groove portion 61 of the concentrating roller 50 having such a flat portion 61a and the optical fiber core wire G2 is passed, as shown in FIGS. The core G2 rolls on the flat surface portion 61a in the groove portion 61 so that the portion with high rigidity in the cross section is inside the curve. That is, the optical fiber core wire G2 in which the glass fiber G1 is periodically eccentric in the longitudinal direction is rolled and twisted on the flat surface portion 61a so that the glass fiber G1 side having high rigidity becomes the flat surface portion 61a side. Thereby, as for the optical fiber core wire G2, the eccentric position of the glass fiber G1 is arrange | positioned at the one side in a cross section. Therefore, on the downstream side of the concentrating roller 50, the optical fiber core wire G2 is in a state to which an elastic torsional strain is periodically applied in which the twisting direction is periodically reversed in the longitudinal direction.

  Therefore, as shown in FIG. 8, in the optical fiber ribbon G3 in which a plurality of optical fibers G2 to which torsional strain is applied are integrated into a tape shape by a coating H2 made of a taped resin, as shown in FIG. In addition, a plurality of optical fiber core wires G2 are integrated with the elastic twisting strain in which the twisting direction is periodically reversed in the longitudinal direction. In the example of FIG. 8, the eccentric position of the glass fiber G1 is shifted downward in the drawing, and this arrangement is continuous over the entire length of the optical fiber ribbon G3. Each optical fiber core wire G2 returns to the state where the glass fiber G1 is eccentric in a spiral shape in the longitudinal direction (see FIG. 3) when the integration by the coating H2 is released.

  In the optical fiber ribbon G3, the optical fiber G2 has an elastic torsional strain in which the twist direction is periodically reversed in the longitudinal direction, so that the polarization mode dispersion is canceled in the longitudinal direction. The polarization mode dispersion of each optical fiber core line G2 can be reduced. Further, as compared with a structure in which twist is continuously applied in one direction, the bending of the optical fiber core wire G2 can be suppressed as much as possible, and the handleability can be improved.

  Further, when the integration by the coating H2 is released, each optical fiber core wire G2 returns to a state where the glass fiber G1 is eccentric in a spiral shape in the longitudinal direction (see FIG. 3). At the time of integration by the coating H2, the helical change of the eccentric position is forcibly made linear, whereby an elastic torsional strain can be applied to the optical fiber core wire G2. Thereby, polarization mode dispersion can be reduced.

  The eccentric rotation speed of the glass fiber G1 is preferably 0.2 times / m or more and 8.0 times / m or less. Thereby, the polarization mode dispersion of each optical fiber core line G2 can be surely reduced, and the handling property can be improved.

  In addition, according to the above-described manufacturing method of the optical fiber ribbon, the optical fiber core G2 having an elastic torsional strain in which the twist direction is periodically reversed in the longitudinal direction is taped. The optical fiber ribbon G3 in which the polarization mode dispersion of G2 is reduced can be easily obtained.

  In particular, since the optical fiber core wire G2 in which the glass fiber G1 is periodically eccentric in the longitudinal direction is integrated with the taped resin with the eccentric position of the glass fiber G1 aligned in one direction, each optical fiber core is integrated. The optical fiber ribbon G3 in which the polarization mode dispersion of the line G2 is reduced can be easily manufactured. In addition, it is possible to obtain an optical fiber ribbon G3 having excellent handling properties by suppressing the bending of the optical fiber G2 as much as possible.

  In the above-described embodiment, the optical fiber core wire G2 in which the glass fiber G1 is eccentric while being periodically inverted in the longitudinal direction is used. However, the optical fiber core wire G2 in which the glass fiber G1 is not eccentric is used. The core wire G3 may be manufactured.

In this case, as shown in FIG. 10, when rewinding from the reel 70 around which the non-eccentric optical fiber core G2 is wound to another reel 71, it is periodically twisted in the longitudinal direction by the swing roller 72. Is granted. Then, a plurality of optical fiber core wires G2 provided with twists in this way are arranged and integrated by tape formation to obtain an optical fiber tape core wire G3.
Also in the optical fiber ribbon G3 manufactured in this way, a plurality of optical fiber cores G2 having an elastic torsional strain whose twist direction is periodically reversed in the longitudinal direction are integrated.

  In this case, in the optical fiber tape core manufacturing apparatus 40 in which a plurality of optical fiber cores G2 are integrated with a resin to form the optical fiber tape core G3, a concentrator having a groove 61 formed with a flat surface portion 61a. Instead of the roller 50, a concentrator roller 74 having a V-shaped groove 73 is used as shown in FIG. That is, when the concentrating roller 74 having the V-shaped groove 73 is used, the optical fiber core wires G2 to which twist is applied can be arranged while being twisted and integrated by the covering H2.

  When the optical fiber ribbon G3 is manufactured by using the non-eccentric optical fiber G2 in which the glass fiber G1 is not eccentric, as shown in FIG. 12, a concentrating roller 74 having a V-shaped groove 73, An optical fiber ribbon manufacturing apparatus 81 provided with a swing roller 80 between the supply 41 may be used.

  According to this optical fiber ribbon manufacturing apparatus 81, the non-eccentric optical fiber G <b> 2 fed out from the reel 70 of the supply 41 is periodically twisted in the longitudinal direction by the swing roller 12. Then, the optical fiber core wire G2 to which the twist is applied in this manner is arranged by arranging the optical fiber core wire G2 to which the twist is applied by the concentrating roller 74 having the V-shaped groove portion 73 while maintaining the twist. The coating H2 is applied and integrated.

  And if the manufacturing apparatus 81 of the optical fiber tape core wire provided with the concentrating roller 74 which has this V-shaped groove part 73, and the rocking | fluctuation roller 80 is used, twist is provided to the non-eccentric optical fiber core wire G2, The twists can be arranged while being held, and can be integrated by being covered with a taped resin.

  According to the optical fiber ribbon manufactured in this way, the optical fiber G2 is integrated with the taped resin while being twisted while periodically changing the direction, so that the polarization of each optical fiber G2 is polarized. The optical fiber ribbon G3 with reduced mode dispersion and excellent handling properties can be easily manufactured.

  Further, without providing the swing roller 80, the reel 70 of the supply 41 may be swung while being periodically reversed with the axis orthogonal to the rotation axis of the reel 70 as the rotation axis.

  In addition, while the glass fiber G1 is periodically inverted in the longitudinal direction, the eccentricity of the eccentric optical fiber G2 is returned to impart torsional strain, and the optical fiber G2 is twisted while periodically reversing the direction. Tapes may be used. In this case, it is preferable that the rotation period in the eccentric direction of the glass fiber G1 in the optical fiber core G2 is different from the inversion period in the twist direction of the elastic torsional strain. The polarization mode dispersion of G2 can be further effectively reduced.

At the time of manufacturing the optical fiber, the polarization mode dispersion and the amount of optical fiber bending (curvature radius) when the eccentric rotation speed of the glass fiber by the swing roller was changed by several levels were investigated.
In addition, when the amount of eccentricity of the glass fiber is excessively increased, the alignment step when the optical fiber tape is formed is deteriorated. Therefore, the experiment was performed with the amount of eccentricity of 3 to 30 μm.
The results are shown in Table 1 and FIG.

As shown in Table 1 and FIG. 13, it was found that good PMD characteristics can be obtained by setting the eccentric rotation speed of the glass fiber to 0.2 (times / m) or more. However, it has been found that when the eccentric rotation speed is 9 (times / m) or more, the curvature of the optical fiber increases abruptly and the radius of curvature decreases, which affects the handling property.
Therefore, the PMD is set to 0.15 (ps / s) by setting the eccentric rotation speed of the glass fiber in the optical fiber core wire within a certain range (0.2 times / m or more and 8.0 times / m or less). √ km) or less, the radius of curvature of the optical fiber can be set to 6 (m) or more, and it was found that both good PMD characteristics and handling properties can be achieved.

  In PMD determination, 0.2 (ps / √km) or less was determined to be good, and 0.2 (ps / √km) or more was determined to be defective. The determination of the radius of curvature of the optical fiber was determined to be good when 4 (m) or more was good and less than 4 (m). In the comprehensive determination in Table 1, A (good) was determined to be good in both PMD and radius of curvature, and B (defective) was determined to be defective on either side.

  Further, a four-fiber optical fiber ribbon is manufactured by using an optical fiber having an eccentric rotation speed of 3 (times / m), and a slot groove for receiving the optical fiber ribbon is provided. PMD was evaluated when it was housed in a 200-fiber tape slot type cable. As a result, PMD could be reduced by 40% compared to a cable containing an optical fiber core without eccentric rotation.

It is a schematic block diagram which shows an example of the manufacturing apparatus of the optical fiber core wire used for the optical fiber tape core wire which concerns on this invention. It is a schematic diagram which shows the motion of the rocking | swiveling roller of the manufacturing apparatus of FIG. It is a schematic perspective view of the optical fiber core wire which the glass fiber decentered. It is a block diagram which shows an example of the manufacturing apparatus which manufactures the optical fiber ribbon based on this invention. It is a schematic sectional drawing of the groove part of the concentrating roller which arranges an optical fiber core wire. It is a schematic sectional drawing of the groove part of a concentrating roller which shows the motion of the optical fiber core wire in the groove part of a concentrating roller. It is a schematic side view of the concentrating roller which shows the movement of the optical fiber core wire in the groove part of the concentrating roller. 1 is a cross-sectional perspective view of an optical fiber ribbon according to the present invention. It is a graph which shows the twist distortion of the optical fiber core wire which comprises the optical fiber tape core wire which concerns on this invention. It is a figure which shows the other method of providing twist to an optical fiber core wire. It is a schematic sectional drawing which shows the groove part of another concentrating roller. It is a schematic block diagram which shows the manufacturing apparatus of another optical fiber tape core wire. It is a graph which shows the relationship between the eccentric rotation speed of an optical fiber core wire, and various characteristics in an optical fiber tape core wire.

Explanation of symbols

1: optical fiber core manufacturing apparatus, 12: swing roller, 40, 81: optical fiber ribbon manufacturing apparatus, 50: concentrating roller, 61: groove, G1: glass fiber, G2: optical fiber core, G3: optical fiber ribbon, H1: coating (resin), H2: coating (taped resin)

Claims (4)

A plurality of optical fiber cores in which glass fibers are coated with a resin are juxtaposed, and the entire circumference is covered with a taped resin and integrated,
The optical fiber core has an elastic torsional strain in which the twisting direction is periodically reversed in the longitudinal direction ,
The optical fiber core has a portion in which the glass fiber is eccentric with respect to the resin in a state where the integration is released, and the eccentric position spirally changes in the longitudinal direction.
An optical fiber ribbon, wherein a period of rotation of the glass fiber in the eccentric direction of the optical fiber is different from a period of reversal of the twist direction of the twist strain. The optical fiber ribbon according to claim 1,
  An optical fiber ribbon having an eccentric rotation speed of the glass fiber of 0.2 times / m or more and 8.0 times / m or less. An optical torsional strain in which a glass fiber is eccentrically spirally coated in the longitudinal direction and coated with a resin, and the eccentric position of the glass fiber is aligned in one direction and is periodically reversed in the longitudinal direction. Is a method of manufacturing an optical fiber ribbon in which a plurality of fibers are juxtaposed in parallel with each other, and the entire circumference is covered with a taped resin and integrated.
  A method of manufacturing an optical fiber ribbon, wherein a period of rotation of the glass fiber in the eccentric direction of the optical fiber is different from a period of inversion of the twist direction of the twist strain. It is a manufacturing method of the optical fiber tape cable core according to claim 3,
  A method of manufacturing an optical fiber ribbon, wherein the optical fiber strands are integrated with the taped resin while twisting by periodically reversing the twist direction.

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