JPH0715058A - Optical fiber and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an optical fiber which can be made compact without sacrifice of reliability and can be fixed easily in the form of coil having small diameter. CONSTITUTION:A carbon coat layer is formed on the surface of an optical fiber doped with a rare earth element and then a metal coat layer is formed thereon by electrolytic plating to produce a metal coat optical fiber 23 which is then coiled 23a and bonded by means of a solder 24 thus obtaining an optical fiber coil 26. This structure allows miniaturization of an optical amplifier mounted with an optical fiber coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coiled optical fiber (hereinafter referred to as an optical fiber coil) used for an optical amplifier or the like.

[0002]

2. Description of the Related Art In recent years, an optical fiber doped with a rare earth has been actively developed by amplifying a signal of a communication wavelength and utilizing it. 2. Description of the Related Art Conventionally, an optical fiber coil used for an optical amplifier is formed by winding an optical fiber of several meters to several tens of meters around a metal reel in a coil shape and coating several turns of the outermost layer with an adhesive. Mounted in the amplifier package. The problem of such an optical amplifier is miniaturization for forming a high-level communication network, but in order to achieve the object, it is desired to make the optical fiber coil compact, that is, to develop a small diameter winding. .

However, the quartz glass constituting the optical fiber has a very high hardness and exhibits a strong restoring force when wound with a small diameter, and it is very difficult to fix it after winding with a small diameter. Further, when the optical fiber is wound around the metallic reel, it is difficult to align and wind the optical fiber sequentially from one side of the reel, and in addition, the side pressure from the reel is easily received and the optical characteristics are easily deteriorated. Furthermore, the fiber diameter is about 12
Since it is as thin as 5 μm, it exhibits sufficient flexibility, but even a slight surface scratch may cause breakage, and particularly when wound with a small diameter, breakage may occur due to lateral pressure. For these reasons, it was difficult to maintain reliability of the optical fiber coil having a winding diameter of 30 mm or less for a long period of time.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain an optical fiber coil which can be easily fixed after winding an optical fiber with a small diameter and can be made compact without impairing the reliability of the optical fiber. It is in.

[0005]

This problem is solved by forming a metal-coated layer on the surface of a carbon-coated optical fiber by electrolytic plating to obtain a metal-coated optical fiber, and then winding the metal-coated optical fiber. Is solved, molten solder is applied to the metal coating layer of the metal coated optical fiber of the winding portion, and the metal coated optical fiber is fixed by solder to form an optical fiber coil.

[0006]

In the present invention, the carbon coating layer of the carbon coated optical fiber acts as a conductor and the non-conductive optical fiber is subjected to electrolytic plating to form a solderable metal coating layer. Then, the metal-coated optical fiber is wound to form a wound portion, and when the molten solder is applied to the metal-coated layer of the metal-coated optical fiber of the wound portion, the metal coating layer and the metal adjacent to the wound portion are formed. The coat layer is welded by solder, and the restoring force becomes difficult to work,
The metal-coated optical fiber can be fixed in a substantially wound state. Further, since the optical fiber is not wound around a metallic reel or the like, the optical characteristics are not deteriorated by the lateral pressure from the reel, and the breaking is not caused by the lateral pressure when wound in a small diameter. Therefore, it is possible to easily fix the optical fiber after the small-diameter winding, and it is possible to make the optical fiber coil compact without impairing the reliability of the optical fiber.

[0007]

Embodiments of the optical fiber coil of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a metal-coated optical fiber according to the present invention. This metal coated optical fiber comprises an optical fiber 2, a carbon coating layer 3 and a metal coating layer 4.

In order to obtain this metal coated optical fiber, first, the carbon coated layer 3 is formed on the surface of the optical fiber 2 by the CVD method to obtain the carbon coated optical fiber. The optical fiber 2 used here has a diameter of about 20 mm.
In order to minimize deterioration of optical characteristics when wound around the core rod, the core rod is designed to be strong against bending with a high relative refractive index difference. When manufacturing an optical fiber coil used for an optical amplifier, a rare earth-doped optical fiber is used. The rare earth-doped optical fiber has a higher power density to the core portion in order to optimize the amplification efficiency and meets the specifications. The carbon coat layer 3 has a thickness of about 0.05.
Since it is as thin as μm and does not retain sufficient conductivity, a metal coat layer 4 is further formed on the surface of the metal coat layer by electrolytic plating.

FIG. 2 is a schematic view showing an example of an electroplating apparatus for forming the metal coat layer 4, and reference numeral 11 in the figure indicates carbon that is passed between the take-up drum 12 and the delivery drum 13. It is a coated optical fiber. The carbon-coated optical fiber 11 delivered from the delivery drum 13 passes through the plating solution 14 a in the plating tank 14 and is wound up on the take-up drum 12. The plating solution 14a
An annular anode 15 is provided in the inside of the plating tank 1.
It is connected via a power supply 18 to a metal roller 17 which is one of the cathodes of the rollers 16 and 17 for passing 4 through.
The roller 16 is insulated.

In order to form the metal coat layer 4 using this apparatus, the carbon coat layer 3 is provided with a function as a cathode through the metal roller 17 and an electric current is applied between the carbon coat layer 3 and the anode 15 in the plating solution 14a. The target metal is deposited and deposited on the surface of the optical fiber by.

That is, in the first step, the surface of the carbon coating layer 3 is coated with a primary metal layer of about 0.1 to 1.0 μm by strike plating. Strike plating is a method of cleaning and activating the surface with hydrogen gas generated in a liquid. Although the deposition rate is low, a stable metal film can be obtained even when the surface has low conductivity. The primary metal layer provides the surface with sufficient conductivity.

Next, as a second step, electrolytic plating treatment with a sufficient current density is performed to coat the surface of the primary metal layer with a secondary metal layer. The coating film thickness is determined by the current density and the processing time, that is, the linear velocity of the carbon-coated optical fiber that passes through the plating tank. Since the surface resistance is uniquely determined by the material to be coated, it is necessary to slow the linear velocity or lengthen the processing time in order to obtain the film thickness. Since the former leads to deterioration of productivity, it is desirable to adjust the processing time of the latter. For this purpose, a continuous processing method in which the secondary metal layer is connected in tandem in the axial direction of the carbon-coated optical fiber 11 is adopted.

As the material of the metal coat layer 4, it is preferable to use nickel, copper or the like having excellent solderability.
The solderability was determined based on the determinations of the solder wettability on the surface and the solder erodibility associated with soldering.

Soldering corresponds to an alloy reaction between the solder and the target metal, and when the alloy formation region reaches the interface of the carbon coat layer 3 provided with the metal coat layer 4, delamination is likely to occur. . For solder erosion, it was determined whether or not peeling would occur with soldering. As a result, the thickness of the metal coating layer 4 which does not cause peeling due to soldering is 2 μm or more for nickel, and copper has a larger amount of solder erosion than nickel.
It has been found that it is preferable that the thickness is μm or more.

When nickel is used as the material of the metal coat layer 4, it has good solderability immediately after coating, but is easily oxidized by oxygen in the atmosphere, and the oxidized nickel has extremely deteriorated solderability. I knew that. Further, when copper is used as the material of the metal coat layer 4, the oxide layer can be removed by using the flux even after it has been oxidized, and there is no problem, whereas the oxidized nickel is very removed by the flux. It is known to be difficult to do.

In order to solve this problem, as shown in FIG. 3, a protective layer 5 is formed on the surface of the metal coating layer 4 made of nickel.
It is desirable to form the metal-coated optical fiber 23 so as to form it.

Gold or the like is preferably used as the material of the protective layer 5. Au is a material that can be easily applied to both electrolytic plating and electroless plating, and the method is properly used depending on the case. Electroless plating is suitable for processing short objects, and electrolytic plating is suitable for online long processing. Au exhibits excellent stability in the atmosphere and is a very excellent material in a corrosive atmosphere. Furthermore, the solder wettability is also very excellent. However, since solder erosion is very high, when it is used alone, almost all becomes an alloy layer with the solder.
A thickness of 00 μm or more is required. From these facts, by combining the protective layer 5 made of gold and the metal coating layer 4 made of nickel, it becomes possible to give excellent surface wettability and slight solder erosion. If the thickness of the protective layer 5 made of gold is 0.1 μm or more, it is possible to sufficiently provide desired corrosion resistance and oxidation resistance. Also,
It is also possible to combine this with copper and still provide corrosion resistance.

Next, a method of manufacturing an optical fiber coil using the above metal coated fiber will be described. Figure 4
(A), (B), (C), (D) is a figure which shows an example of the process of manufacturing an optical fiber coil using the metal coat fiber 23. First, as shown in FIG. 4A, the peeling removal material 21 is wrapped around the core rod 22. The material for the peeling / removing material 21 is not limited as long as it can be easily peeled / removed from the metal-coated optical fiber coated with solder, and for example, paraffin paper is used.
The material of the core rod 22 is not specified as long as it can be easily pulled out from the peeling / removing material 21 around which the metal-coated optical fiber 23 is wound. The diameter of the core rod 22 is set according to the diameter of the target optical fiber coil.
In this embodiment, the diameter of the optical fiber coil is set to be about 20 mm.

Then, as shown in FIG. 4B, the core rod 2
After the metal-coated optical fiber 23 is wound around the surface of the stripping / removing material 21 wound around 2, the winding portion 23a is formed and temporarily fixed, the core rod 22 is pulled out from the stripping / removing material 21.
As a method of winding the metal-coated optical fiber 23, the winding section 2
It is preferable to perform the aligned winding so that the interval between the adjacent metal-coated optical fibers 23 of 3a and the metal-coated optical fiber 23 is as narrow as possible. The number of turns and the interval between the adjacent metal-coated optical fibers 23 and the metal-coated optical fibers 23 are not specified and can be changed according to the application.

Next, as shown in FIG. 4C, the metal coated optical fiber 23 is dipped together with the peeling / removing material 21 in a solder bath 25 filled with solder 24. This solder bath 25 is kept at about 260 ° C.
Is sufficiently melted. It is desirable that the solder 24 does not contain flux.

After that, when the metal coated optical fiber 23 is taken out from the solder bath 25, the metal coated optical fiber 2
Since the metal coat layer 4 made of a metal having excellent solderability is formed on the surface of No. 3, the metal coat layer 4 is selectively formed.
Is soldered.

Then, as shown in FIG. 4D, an optical fiber coil 26 is obtained by removing the peeling-removing material 21 from the metal-coated optical fiber 23. In the optical fiber coil 26, the metal coat layer 4 and the metal coat layer 4 of the metal coat optical fibers 23 adjacent to each other in the winding portion 23a are welded and fixed by the solder 24. The peeling / removing material 21 can usually be easily peeled / removed. However, when the peeling / removing material 21 is adhered to the metal-coated optical fiber 23 due to flux, oil on the surface of the peeling / removing material 21, or the like, the surface is lightly rubbed with flame. Can be removed easily.

In this embodiment, the carbon coating layer 3 on the surface of the optical fiber 2 acts as a conductor, and the non-conductive optical fiber 2 is electroplated to form a solderable metal coating layer 4. be able to. Also, the winding part 2
The metal coat layer 4 and the metal coat layer 4 of the metal coat optical fiber 23 of 3a are welded by the solder 24, the restoring force becomes difficult to work, and it can be fixed in a substantially wound state. Further, since the optical fiber 2 is not wound around a metallic reel or the like, the optical characteristics are not deteriorated by the lateral pressure from the reel, and the breaking is not caused by the lateral pressure when wound in a small diameter. Further, since the solder is used to fix the wound metal-coated optical fiber 23, it is possible to fix the metal-coated optical fiber 23 to a metal plate such as copper by soldering with a normal soldering iron, and to the package of the optical amplifier. Is easy to implement. Therefore, the optical fiber 2 can be easily fixed after being wound with a small diameter, and the optical fiber coil 26 can be made compact without impairing the reliability of the optical fiber 2, and the optical amplifier in which the optical fiber coil 26 is mounted is mounted. Can be downsized. Further, since the adhesive is not used for fixing the metal-coated optical fiber 23 in the winding portion 23a, the adhesive is not melted by heat, and there is no step of drying the adhesive, so that heat resistance and manufacturing The speeding up can be improved.

In the manufacturing method of the present invention, the core rod 22
If a material such as glass or ceramic to which solder 24 does not adhere is used as the peeling removal material 21, the peeling removal material 21 can be omitted. In addition to the method of immersing in the solder bath 25, a method of dropping molten solder onto the winding portion 23a can be adopted. Further, it is not necessary to fix the whole winding part 23a with solder, but only a part of the winding part 23a may be fixed with solder along the longitudinal direction. The point is that the winding part 23a is sufficient to maintain its shape. I wish I had it.

[0025]

As described above, the optical fiber coil of the present invention has the winding part around which the metal-coated optical fiber having the metal coating layer is wound, and the metal-coated optical fiber of this winding part is wound. Since the fiber is fixed by solder, the metal coating layer and the metal coating layer of the metal coated optical fiber in the winding part are welded by the solder, the restoring force becomes difficult to work, and it is almost wound. Fixed. Further, since the optical fiber is not wound around a metallic reel or the like, the optical characteristics are not deteriorated by the lateral pressure from the reel, and the breaking is not caused by the lateral pressure when wound in a small diameter. Also, since solder is used to fix the metal-coated optical fiber in the wound state,
It can be fixed to a metal plate such as copper by ordinary soldering, and the optical amplifier can be easily mounted on a package. Therefore, it is easy to fix the optical fiber after winding it in a small diameter, and it is possible to make the optical fiber coil compact without impairing the reliability of the optical fiber, and it is possible to miniaturize the optical amplifier in which the optical fiber coil is mounted. It has the advantage of being possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a metal-coated optical fiber in an example.

FIG. 2 is a schematic view showing an example of an electrolytic plating apparatus for forming a metal coat layer in Examples.

FIG. 3 is a cross-sectional view showing an example of a metal-coated optical fiber in which a protective layer is formed in the example.

FIG. 4 is a diagram showing a process of manufacturing an optical fiber coil using the metal-coated fiber.

[Explanation of symbols]

2 ... Optical fiber, 3 ... Carbon coat layer, 4 ... Metal coat layer, 5 ... Protective layer, 11 ... Carbon coat optical fiber, 12 ... Take-up drum, 13 ... Delivery drum, 14
... plating bath, 14a ... plating solution, 15 ... anode, 16
... roller, 17 ... metal roller (cathode), 18 ... power supply, 21 ... peeling removal material, 22 ... core rod, 23 ... metal-coated optical fiber, 23a ... winding part, 24 ...・ Solder, 2
5 ... Solder bath, 26 ... Optical fiber coil

Claims (4)

[Claims] 1. An optical fiber coil having a winding portion formed by winding a metal-coated optical fiber having a metal coating layer formed thereon, and the metal-coated optical fiber of the winding portion being fixed by solder. 2. The optical fiber coil according to claim 1, wherein the metal-coated optical fiber is a metal-coated optical fiber having a protective layer formed on the outermost layer thereof. 3. The optical fiber coil according to claim 1, wherein the optical fiber is a rare earth-doped optical fiber. 4. A metal-coated optical fiber is obtained by forming a metal-coated layer on the surface of a carbon-coated optical fiber by electrolytic plating, and then the metal-coated optical fiber is wound to form a winding portion, and the winding portion is formed. 2. A method for producing an optical fiber coil, which comprises applying molten solder to the metal coating layer of the metal coated optical fiber and fixing the metal coated optical fiber with solder.