JPH04240808A - Clamp for optical fiber - Google Patents

Abstract

PURPOSE:To improve positioning precision of the clamp mechanism in an optical fiber coupler manufacturing device. CONSTITUTION:The clamping mechanism is constituted from a member with groove 1 and a pressing member 2. The member with groove 1 is provided with a groove part 1a where the optical fiber is inserted and an optical fiber conducting part 1b opening up to its exterior. At the time of clamping, the optical fiber is inserted to the groove part and clamped by positioning the optical fiber to the optical fiber conducting part in a state where the member with groove and the pressing member are separated, and then moving the pressing member from the conducting part toward the groove part so that the optical fiber is pressed in.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber clamp used in an apparatus for manufacturing optical fiber couplers used in communication systems and sensor systems.

0002

2. Description of the Related Art In constructing an optical communication system, an optical data link network, etc., an optical branching device that distributes optical signals emitted from a light source in a desired ratio is an important component. One type of optical splitter is an optical fiber coupler, which is usually made by heating and melting multiple optical fiber couplers, fusing them together, and then stretching the fused part under constant tension. It is something. During fusion splicing, it is necessary to closely align the glass parts of the optical fibers in parallel, and a clamp mechanism is used for this purpose, but the accuracy of clamp alignment greatly depends on the characteristics of the manufactured optical fiber. influence

[0003] The conventionally used clamp is
As described in Japanese Patent No. 3-118705, the optical fiber was held down from two directions. Figure 10 shows
It is a perspective view of the clamp described in the above publication, in which two optical fibers 3 and 4 are held vertically by a clamp 28, and the lined up optical fibers are held from the side by a horizontal position adjustment device 24 to align them. It is something.

[0004] Since such conventional clamps are pressed from two orthogonal directions at positions shifted in the axial direction, they are often twisted and clamped. Furthermore, if the groove of the clamper 28 is deeper than the diameter of the optical fibers 3 and 4, as shown in FIG.
As shown in the figure, they shift and it is difficult to align them horizontally.

As shown in FIG. 12, it is conceivable to use two position adjusting devices, a vertical position adjusting device 23 and a horizontal position adjusting device 24, as the clamper mechanism, but either position adjusting device first connects the optical fiber. 3 and 4, and if the horizontal position adjustment device 24 is used first, Fig. 1
It is much more likely that the result will be as shown in Figure 3 (B) than as shown in Figure 3 (A).

After that, even if the vertical position adjustment device 23 is used, the horizontal position adjustment device 24 becomes as shown in FIG.
The optical fibers 3 and 4 remain axially displaced. The same applies if the vertical position adjustment device 23 is used first.

[0007] Therefore, with the conventional method of separately clamping from two orthogonal directions, there is a problem in that good clamping cannot be expected.

[0008] Furthermore, the optical fiber fixing device described in Japanese Utility Model Application Publication No. 1-94904 uses a pair of optical fiber clamping tools having a thickness and a step smaller than the diameter of the optical fiber and larger than the radius. However, the workability is poor,
The problem is that it is difficult to use.

In the optical fiber coupler manufacturing apparatus described in Japanese Patent Application Laid-Open No. 64-80913, two blocks with V-grooves are used, one optical fiber is housed in each V-groove, and the V-groove is The two optical fibers are pressed against each other from both sides by the groove walls to tightly sandwich them.

[0010] In this way, when using a V-groove, the size of the V-groove is such that when the two blocks are in contact as shown in FIG. 14(A), the two optical fibers 3 and 4 are It cannot be larger than touching.

In the state shown in FIG. 14(A), the state shown in FIG.
), when the angle of the V-groove is 90 degrees, and the radius of the optical fiber is r, the width M of the opening of the V-groove is M=2.
(1+21/2)r. Therefore, as shown in FIG. 3(C), the maximum possible value of the width D of the opening of the V-groove is M shown in FIG. 3(B). If the diameter 2r of the optical fiber is 125 μm, M is 600 μm.
m.

Therefore, in practice, the opening width D of the V-groove is approximately 200 to 300 μm, which is very small. Therefore, a microscope is required to insert the optical fiber into this V-groove.

Furthermore, it is rare for two optical fibers to be completely parallel to the V-groove due to curling habits, etc., and it is normal for them to be slightly deviated from each other. Therefore, in the method described in Japanese Patent Application Laid-Open No. 64-80913, it is necessary to confirm that the optical fiber is completely inserted into the V-groove, and since this work is also done using a microscope, it is difficult for the operator to see. It's hard considering how tired I am.

[0014]

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and provides an optical fiber clamp that has good workability and can easily and reliably hold optical fibers in parallel. It was done for the purpose of

[0015]

[Means for Solving the Problems] The present invention, in the invention set forth in claim 1, provides an optical fiber clamp comprising:
A grooved member having a groove into which an optical fiber is inserted and an optical fiber introduction part expanding outward from the groove, and a grooved member for pushing the optical fiber from the introduction part toward the groove in proximity to the grooved member. The grooved member and the pushing member are separated from each other when not clamped, and when clamped, the pushing member is movably arranged.
The grooved member is characterized in that it is fixed at a clamping position, and in the invention according to claim 2, the pushing member and/or the grooved member are air floating bearings. In the invention according to claim 3, the position of the pushing member and/or the grooved member is secured by stopping the air supplied to the air floating bearing. It is characterized by:

[0016] The grooved member and the pushing member may be supported by the same movement guide shaft.

[0017] Furthermore, the grooved member may push the optical fiber by the thickness of the coating of the optical fiber.

[0018] The push member may be moved by a weight or an electromagnet.

[0019]

[Operation] As shown in FIG. 2, the clamp of the present invention positions the optical fiber in the optical fiber introduction part of the grooved member with the grooved member and the pushing member separated, and the pushing member The optical fiber can be inserted into the groove and clamped by pushing the optical fiber from the fiber introduction part toward the groove.

By supporting the pushing member and/or the grooved member with an air floating bearing, the pushing member and/or the grooved member can be moved with low frictional force, and the air supplied to the air floating bearing can be moved. By stopping , the position of the push member and/or the grooved member can be secured.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram of an optical fiber coupler manufacturing apparatus for explaining an embodiment of the present invention. In the figure, 1 is a grooved member, 2 is a push member, 3 and 4 are optical fiber glass parts, 5 is an optical fiber coating part, 6 is a heat fusion part,
7 is a burner, 8 is a flame, 9 is a clamp for the covering part, 10
is a stretching stage, 11 is a slider, 12 is a stand, 1
3 is a guide shaft. The slider 11 and the guide shaft 13 constitute a linear bearing.

The clamp composed of the grooved member 1 and the pusher member 2 has a groove into which the glass portions 3 and 4 (two in this figure) of the optical fiber from which the coating has been removed are inserted, but details are not given. This will be explained later. After the glass portion of the optical fiber is fixed with this clamp, the outer side of the optical fiber is clamped with the covering clamp 9. The coating clamp 9 is placed on a stretching stage 10 for stretching the optical fiber in the axial direction,
The covering portions 5 of the two optical fibers arranged side by side are clamped from the lateral direction. The heat-fused portion 6 at the center of the glass portions 3 and 4 of the optical fiber aligned in parallel by the grooved member 1 and the push member 2 is heated by the flame 8 of the burner 7 and is fused.

Thereafter, the grooved member 1 and the pushing member 2 are separated, and the heat-fused part 6 is heated by the flame 8 while being tensioned by the stretching stage 10 on which the coating clamp 9 that fixes the optical fiber coating part 5 is placed. has been added. The heat-fused portion 6 is stretched by this tension, and when a predetermined branching ratio is obtained, the stretching is stopped and an optical fiber coupler is manufactured.

FIG. 2 is an explanatory diagram of an embodiment of the optical fiber clamp of the present invention. In the figure, 1 is a grooved member, 1a
1b is a groove, 1b is an optical fiber introduction part, 1c is a groove into which a pushing member is inserted, and 2 is a pushing member. As shown in the perspective view of FIG. 2(A), in this clamp, the optical fiber is inserted into the groove 1a of the grooved member 1, and the pushing member 2 presses the optical fiber to clamp it. be. The pushing member 2 is configured to have a width that allows it to fit into the groove 1c of the grooved member.

Note that the optical fiber is inserted into the groove 1a of the grooved member 1.
Since the grooves 1a are inserted side by side and pressed from the outside by the pushing member 2, the height of the groove 1a is at least as high as 1 of the optical fibers.
．． About 5 times as much is required. If it is larger than that, there is no problem as the optical fiber can be fully accommodated in the groove 1a, but as shown in Figure (B), if the bottom of the groove 1c is higher than the bottom of the groove 1a, the groove The difference h between the bottom of the groove 1a and the bottom of the groove 1c needs to be at least about 1.5 times the length of the optical fiber. In this case, the groove 1a is also extended at the bottom of the groove 1c. The bottom of the groove 1c may be lower than the bottom of the groove 1a. However, if the bottom of the groove 1c is higher than the bottom of the groove 1a, there is an advantage that the force exerted on the optical fiber by the pushing member 2 is evenly distributed.

The groove width is, for example, 125 mm in diameter of the optical fiber.
In the case of μm, a slightly larger value of about 130 μm is preferable. If the diameter accuracy and processing accuracy of the optical fiber are good, the groove width can be close to 125 μm. As mentioned above, the depth of the groove should be at least 125 μm x 1.5 = 187.5 μm, which is 250 μm or more, which is more than twice the diameter of the optical fiber.
It is also possible to make the depth deeper than μm. There is no problem if h as explained in FIG. 2(B) is 187.5 μm or more and 250 μm or less.

According to FIG. 3, the clamp explained in FIG.
The manner in which two optical fibers are clamped will be explained. In the figure, parts similar to those in FIG. 2 are denoted by the same reference numerals, and explanations thereof will be omitted. Note that 3 and 4 are glass parts of the optical fiber.

Ideally or theoretically, if the two optical fibers are well aligned using the sheathing clamp 9 described in FIG. ), but the force due to twisting or bending of the optical fiber itself, or the clamp 9 for the sheathing part
Therefore, it is difficult to align the coating 27 completely, and as shown in FIG.
As shown in (A), in reality, the two optical fibers are separated and their positions are uneven.

Now, as shown in FIG. 3(A), the grooved member 1 is attached to the glass portions 3 and 4 of the optical fiber in the direction indicated by the arrow 26.
Proceed in the direction of. If everything goes well, the glass parts 3 and 4 will fit into the groove 1a, as shown in Figure (B), but if things go wrong, one of the glass parts 4 will not fit into the groove, as shown in Figure (C). Furthermore, as shown in FIG. 1D, both glass parts 3 and 4 may stop at the entrance of the groove 1a and cannot enter the groove 1a. In either state, the two optical fibers can be perfectly aligned by the pushing member 2 pushing the glass portion of the optical fiber into the groove, as shown in FIG.

FIG. 4 is an explanatory diagram of the process of clamping two optical fibers in the optical fiber coupler manufacturing apparatus described in FIG. 1. In the figure, 1, 1' are grooved members, 2,
2' is a pushing member, 3 and 4 are optical fiber glass parts, 5,
5 is a covering portion.

Before clamping, the grooved members 1, 1' and the pushing members 2, 2' are in separate positions, as shown in FIG. 2A. Before starting the fusion process, the grooved members 1, 1'
and the pushing members 2, 2' move to clamp the glass portions 3, 4 of the optical fiber as explained with reference to FIG. In this case, it is important that the glass portions 3 and 4 of the two optical fibers are clamped symmetrically, as shown in FIG. 3B. Therefore, the grooved members 1, 1' and the pushing members 2, 2' each have a glass portion 3 corresponding to the thickness of the coating of the optical fiber.
It is important to press and 4, and in order to set them in this way, it is necessary to consider the position regulation of both and how to apply pressing force.

FIG. 6 is a schematic diagram of a clamp mechanism in an optical fiber coupler manufacturing apparatus for explaining an embodiment in which the clamp is driven using a weight. In the figure, 1 is a grooved member, 2 is a push member, 3 and 4 are optical fiber glass parts, 1
1a and 11b are sliders, 13a and 13b are guide shafts,
14a, 14b are air cylinders, 15 is a stopper, 1
6 is a thread fixing part, 17 is a thread, 18 is a roller, 19 is a weight, 20a and 20b are air supply pipes, and 21a and 21b are air sources. Air sliders are used for the sliders 11a and 11b.

An example of an air slider is shown in FIG. A gap is provided between the guide shaft 13 and the slider 11. A plurality of injection holes 29 are provided around the guide shaft 13, and an air supply pipe 2 attached to one end of the guide shaft 13 is provided.
Connected to 0. When compressed air is introduced into the guide shaft 13 from the air supply pipe 20, the slider 11 can be floated relative to the guide shaft 13 by the pressure of the air flowing out from the injection hole 29. Since the slider 11 is floated by air, the slider 11 can be moved with extremely low friction, and the clamp attached to the slider 11 can be moved with a small force.

The operation of the clamp mechanism shown in FIG. 6 will be explained. When not clamped, as shown in the figure, the grooved member 1 and the pushing member 2 are separated, and the glass parts 3 and 4 of the optical fiber are set between them. The grooved member 1 is an air cylinder 14a.
The glass parts 3 and 4 are moved so as to be accommodated in the grooves. The stop position of the grooved member 1 is controlled by a stopper 15 . The pushing member 2 is moved by the weight 19, the roller 18, and the thread 17 applying force to the thread fixing portion 16. Prior to movement, the pressure applied to the slider 11b by the air cylinder 14b is released. The force of this weight 19 causes the glass parts 3 and 4 of the optical fiber to
is pressed.

On the pushing member 2 side, it is sufficient that the force pushing the optical fiber continues, so if an air slider is used on the pushing member 2 side, after contacting the optical fiber,
Even if the air supply is stopped, there is no problem as the optical fiber is held down. Not only does it save air, but it doesn't cause any problems even if it shakes, so it's actually better that way.

When using the clamp of the present invention,
It is preferable to reduce the force with which the pushing member pushes the optical fiber to prevent damage to the optical fiber. From this point of view, it seems appropriate to use an air floating type bearing on the pushing member side.

FIG. 7A is a schematic diagram of a clamp mechanism in an optical fiber coupler manufacturing apparatus for explaining another embodiment of the clamp drive mechanism. In the figure, parts similar to those in FIG. 6 are denoted by the same reference numerals, and explanations thereof will be omitted. 22 is a magnet mechanism, and 25 is an automatic stage. Grooved member 1
has an important meaning in positioning, so automatic stage 2
5 can be used. The push member 2 side has an electromagnet 22
There is no problem even if it is driven by

FIG. 7(B) is a schematic diagram of a clamp mechanism in an optical fiber coupler manufacturing apparatus for explaining another embodiment of the clamp drive mechanism. In the figure, parts similar to those in FIG. 6 are denoted by the same reference numerals, and explanations thereof will be omitted. In this embodiment, the same guide shaft 13 is used instead of the two guide shafts 13a and 13b explained in FIG. Therefore, positioning of the grooved member 1 and the pushing member 2 is easy.

The method of moving the clamp is not limited to the embodiment described above. Although a well-known linear bearing can be used, it is not limited to a linear bearing as long as a moving mechanism with a large radius is used.

Furthermore, the grooved members 1, 1' and the pushing members 2,
2' may be located at a position shifted in the axial direction of the optical fiber, as shown in FIG. However, since the shearing force applied to the optical fiber increases, the optical fiber becomes more likely to break, so it is necessary to pay sufficient attention to how to apply the pushing force.

Next, the results of an experiment using the mechanism explained in FIG. 6 will be shown. As a comparative example, the clamp mechanism described in FIG. 12 was used. The prototype has a cladding diameter of 125
±1.5μm, MFD 9.5±1μm, cutoff wavelength 1.2μm single mode optical fiber for normal 1.3μm band, outer diameter 0.25m using ultraviolet curable resin.
An optical fiber finished to a diameter of m.m was used. L with wavelength 1.3μm
A D light source was introduced into one optical fiber, and the output light of each optical fiber was detected from the opposite side using a power meter, and the fiber was stretched while monitoring the branching ratio. When the branching state reached 50%, the burner was moved away from the fiber to stop the stretching. Aiming for a branching ratio within 50±3%, we decided to prototype an optical fiber coupler and evaluate excess loss. The length of the exposed glass portion after removing the coating was approximately 30 mm, and an acetylene and oxygen burner were used for heat fusing. For fusion, the optical fiber was heated for 5 minutes to reach a temperature of 1400° C. using a radiation thermometer, and then stretched using a weight of 3 g to provide stretching tension.

Thirty couplers prototyped using the conventional technique and 30 couplers prototyped using the apparatus of the present invention were tested. The average value of excess loss of the couplers manufactured according to the comparative example is 0.
．． 29 dB, and the maximum value was 0.6 dB, whereas the average value of excess loss of the couplers manufactured according to the example was 0.6 dB.
It was 18 dB, and the maximum value was 0.46 dB, which was good.

[0043]

Effects of the Invention As is clear from the above description, according to the optical fiber clamp of the present invention, the optical fibers can be reliably aligned every time during fusion in the optical fiber coupler manufacturing process, and the reproducibility is good. It has now become possible to manufacture optical fiber couplers that are of high quality.

As confirmed from the experimental results, the variation in excess loss of manufactured optical fiber couplers can be reduced, which is effective in improving yield.

Furthermore, since the clamp can be opened and closed automatically, it is effective in saving manpower.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of an optical fiber coupler manufacturing apparatus of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the optical fiber clamp of the present invention.

FIG. 3 is an explanatory diagram of the operating state of the clamp described in FIG. 2;

FIG. 4 is an explanatory diagram of the process of clamping two optical fibers in the optical fiber coupler manufacturing apparatus.

FIG. 5 is an explanatory diagram of the positional relationship of the glass portions of the optical fiber.

FIG. 6 is an explanatory diagram of an embodiment of a drive mechanism for an optical fiber clamp according to the present invention.

FIG. 7 is an explanatory diagram of another embodiment of the drive mechanism for the optical fiber clamp of the present invention.

FIG. 8 is an explanatory diagram of an example of an air slider.

FIG. 9 is a schematic diagram of another embodiment of the optical fiber clamp of the present invention.

FIG. 10 is a perspective view of a conventional clamp.

FIG. 11 is an explanatory diagram of the operating state of the clamp in FIG. 10;

FIG. 12 is a perspective view of another conventional clamp.

FIG. 13 is an explanatory diagram of the operating state of the clamp shown in FIG. 12;

FIG. 14 is an explanatory diagram of another conventional example.

[Explanation of symbols]

1 Grooved member 2 Push member 3, 4...Glass part of optical fiber 5 Optical fiber coating part 6 Heat fusion part 7 Burner 9 Clamp for covering part 10 Stretching stage 11 Slider 12 Stand 13 Guide shaft

Claims (3)

[Claims] 1. A grooved member having a groove into which an optical fiber is inserted, an optical fiber introduction part expanding outward from the groove, and a grooved member that is adjacent to the grooved member and directed from the introduction part toward the groove. the grooved member and the pushing member are separated from each other when not clamped, and when clamped, the grooved member is movably arranged to push the optical fiber. An optical fiber clamp characterized in that it is fixed at a position where it is fixed. 2. The optical fiber clamp according to claim 1, wherein the pushing member and/or the grooved member are supported by an air floating bearing. 3. The optical fiber clamp according to claim 2, wherein the position of the pushing member and/or the grooved member is secured by stopping the air supplied to the air floating bearing.