JPH10325915A - Protective structure for optical fiber coupler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb a shock from the outside by a buffer and to prevent a fused drawing part (optical branching coupling part) inside a protective tube (optical fiber coupler body) from being damaged and ruptured by arranging the buffer on the periphery of the optical fiber coupler body. SOLUTION: The buffer 12 is constituted of the 1st buffer 12a and the 2nd buffer 12b in symmtric structure, and the buffers 12a and 12b are laminated in a non-contact state each other by putting the optical fiber coupler body 10a (protective tube 8) in between. Grooves 12c and 12d having V-shaped cross section are formed in the length direction of the body 10a on the facing surfaces of the buffers 12a and 12b. The body 10a is housed, positioned and held in the grooves 12c and 12d. An arrangement distance d1 between the buffers 12a and 12b is set to about 1 mm. Furthermore, the buffers 12a and 12b are integrated through four screws 13 piercing the buffers 12a and 13b and assembled on an outer surface mount 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective structure for an optical fiber coupler for improving the strength of the optical fiber coupler and simplifying handling.

[0002]

2. Description of the Related Art In the fields of optical communication and optical measurement, optical fiber couplers are frequently used as circuit elements for branching and multiplexing light. This optical fiber coupler generally has a structure in which an input port composed of M optical fibers and an output port composed of N optical fibers are optically coupled at an optical branching / coupling portion. It is called an optical fiber coupler.

Among them, for example, a 2 × 2 type optical fiber coupler is manufactured by a method shown in FIGS. 4 (a) to 4 (d), for example. That is, first, in FIG.
The coating of the middle part of the two optical fibers 1a and 1b having the coating layer 2 is peeled off, and the bare optical fibers 3a and 3b are respectively removed.
Are exposed, and the bare optical fibers 3a and 3b are arranged in parallel. The bare optical fibers 3a and 3b are provided with a core at the center,
It is made of a clad having a lower refractive index than the core provided on the outer peripheral portion of the core.

Then, as shown in FIG. 4B, at least a part of the bare optical fiber 3a, 3b is brought into contact, and the contact portion 5 is fused to each other using an oxyhydrogen flame 6 (or a discharge arc or the like). As shown in FIG. 4 (c), the optical fiber 1a and the optical fiber 1b are optically coupled to each other to form a fusion-stretched extension (optical branch coupling section) 7. Next, FIG.
As shown in the figure, the entire bare optical fiber 3a, 3b including the fusion-spreading portion 7 is housed in a protective tube 8 made of a tubular metal or the like, and the covering portions on both sides of the bare wire and the protective tube 8 are accommodated. Are sealed with a sealing resin 4 at both ends. As a result, the protective tube 8 and the one housed inside the protective tube 8 are used as the optical fiber coupler body 10a, the coating portions of the optical fibers 1a extending from both ends thereof are used as the ports 9a and 9b, and the coating portions of the optical fiber 1b are used. A 2 × 2 type optical fiber coupler 10 having ports 9c and 9d is obtained. That is, the optical fiber coupler body 10a includes at least the protective tube 8 and the entire bare optical fibers 3a and 3b having the fusion-spread portion (optical branching / coupling portion) 7.

The bare optical fibers 3a and 3b are made of, for example, quartz glass and have an outer diameter of 125 μm. Further, the coating layer 2 is made of an ultraviolet curable resin,
The outer diameter of the optical fibers 1a and 1b including the coating layer 2 is, for example, 250 μm. In this case, the outer diameter of the fusion-spread portion 7 is smaller than the bare optical fibers 3a and 3b,
It is about 10 to 50 μm.

[0006]

However, even if the fusion stretched portion 7 is housed in the protective tube 8 as described above, the outer diameter of the fusion stretched portion 7 is very small, about 10 to 50 μm. If an impact is applied from the outside of the protection tube 8, it will be damaged,
It may break. Such an impact occurs, for example, when the optical device equipped with the optical fiber coupler is transported or collides with another external object, or when the optical device is accidentally dropped.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an optical fiber coupler having an optical fiber coupler in which a fusion extending portion (optical branching / coupling portion) is unlikely to be broken when an external impact is applied. The purpose is to provide a protective structure.

[0008]

According to a first aspect of the present invention, there is provided a protective structure for an optical fiber coupler, wherein a buffer material is provided around an optical fiber coupler body. Suggest. According to a second aspect of the present invention, there is provided a protective structure for an optical fiber coupler, wherein a buffer is provided around an optical fiber coupler body in a housing. According to a third aspect of the present invention, there is provided a protection for an optical fiber coupler, wherein a plurality of cushioning members are arranged at intervals around the optical fiber coupler main body in the housing in the longitudinal direction of the optical fiber coupler main body. Propose the structure.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first to third embodiments of the optical fiber coupler protection structure of the present invention shown in FIGS. The optical fiber coupler to be protected is, for example, the 2 × 2 type optical fiber coupler 10 manufactured by the method shown in FIGS. In the 2 × 2 type optical fiber coupler 10, for example, the bare optical fibers 3a and 3b are made of quartz glass and have an outer diameter of 125 μm. Coating layer 2
Is made of an ultraviolet curing resin, and the outer diameter of the optical fibers 1a and 1b including the coating layer 2 is 250 μm. Further, the outer diameter of the fusion-stretched portion 7 is about 10 to 50 μm.

The protection tube 8 is made of metal such as aluminum or stainless steel, glass, or the like, and has an inner diameter of 2 mm, an outer diameter of 3 mm, and a length of 50 mm. The length L1 of the bare optical fiber portion contained in the protective tube 8 is 40
mm. Note that these sizes can be appropriately changed according to the design conditions of the optical fiber coupler.

FIG. 1 shows a first embodiment of a protective structure for an optical fiber coupler according to the present invention, wherein FIG. 1 (a) is a plan view and FIG. 1 (b) is FIG. 1 (a). 2 is a partial side sectional view taken along a broken line AA shown in FIG. In the figure, reference numeral 12 denotes a cushioning material. The cushioning member 12 includes a first cushioning member 12a and a second cushioning member 12b having a symmetrical structure. The first cushioning member 12a and the second cushioning member 12b separate the optical fiber coupler body 10a (protective tube 8). The layers are stacked at intervals without contact with each other. These first cushioning materials 12
a, a groove 1 having a V-shaped cross section is formed on the opposing surface of the second buffer material 12b in the longitudinal direction of the optical fiber coupler body 10a.
2c and 12d are provided, and these grooves 12c and 1d are provided.
The optical fiber coupler body 10a is accommodated in 2d, positioned, and held. The arrangement distance d1 between the first buffer material 12a and the second buffer material 12b is about 1 mm.

Further, by means of four screws 13 penetrating the second buffer material 12b and the first buffer material 12a in order, they are integrated with the optical fiber coupler body 10a therebetween, and the first buffer material is formed. These are assembled on a mounting plate 14 arranged on the outer surface of the material 12a.

The cushioning material 12 (first cushioning material 12a, second cushioning material 12a
The cushioning material 12b) is made of a rubber-like elastic material and has a Young's modulus of 3
It is preferably about 30 kg / mm ² . this is,
The range is set so that the mechanical strength of the cushioning material 12 itself can be obtained to some extent and the buffering effect on the optical fiber coupler 10a can be obtained. That is, if it is less than 3 kg / mm ² , the mechanical strength of the cushioning material 12 is small,
If it exceeds / mm ² , the buffering effect decreases. For example, natural rubber, synthetic rubber, or the like can be used. Alternatively, various synthetic resins, for example, a sponge (porous synthetic resin) made of polyurethane or the like can be used.

In the first cushioning member 12a, if the dimension in the direction of the length of the optical fiber coupler body 10a is the length and the dimension in the direction perpendicular thereto is the width, the length is 6
6 mm and 13 mm in width. In addition, the first cushioning material 12
The thickness t1 of a is 5 mm. Unless otherwise specified, the dimensions of the constituent members will be referred to as the length in the length direction of the optical fiber coupler body 10a in the length direction, and the width in the direction perpendicular to the length thereof. Groove 1
2c has a width of 3.2 mm and a depth of 1.6 mm. These dimensions are the same for the second cushioning material 12b and the groove 12d.

However, the sizes of the first buffer material 12a and the second buffer material 12b can be appropriately changed depending on the size of the 2 × 2 type optical fiber coupler 10 to be protected, and are designed so as to obtain a buffer effect. Just do it. It is most preferable that the cushioning material 12 (the first cushioning material 12a and the second cushioning material 12b) be provided so as to cover the entire length of the optical fiber coupler body 10a in the longitudinal direction, but the invention is not limited to this. For example, a plurality of buffer materials having a length shorter than the length of the optical fiber coupler main body 10a or a plurality of buffer materials having a shorter length than the length of the optical fiber coupler main body 10a are provided at a distance from each other. It can also be placed around.

In this embodiment, the first cushion 1
2a and the second cushioning material 12b are laminated without being in contact with each other, but the first cushioning material 12a and the second cushioning material 12b
By adjusting the thickness of the first cushioning material 12a and the second cushioning material 12b
On the surface opposite to the groove 12c and the groove 12d,
The cushioning member 12a and the second cushioning member 12b may be designed to be in contact with each other. However, by being provided in such a state that they do not come into contact with each other, the degree of freedom between the first cushioning member 12a and the second cushioning member 12b is increased, and the cushioning effect can be improved.

The cross-sectional shape of the grooves 12c and 12d is not limited to a V-shape, but may be changed to a U-shape or the like as appropriate. However, if the optical fiber coupler body 10a is formed in a semicircular shape in close contact with the outer periphery thereof, the optical fiber coupler body 10a
And the contact area between the groove 12c and the groove 12d increases, and the degree of freedom in the length direction of the optical fiber coupler body 10a decreases. Therefore, a shape in which the contact area decreases, such as a V-shape, is selected. Is preferred.

The mounting plate 14 is provided so that the 2 × 2 type optical fiber coupler 10 can be easily mounted on an optical device, but is not essential. When the mounting plate 14 is not provided, only the first cushioning material 12a and the second cushioning material 12b may be fixed by the screws 13. The length of the mounting plate 14 is 75 mm, the width is 20 mm, and the thickness is 3 m
m.

In the first embodiment, since the buffer 12 is disposed around the optical fiber coupler body 10a, the buffer 12 absorbs the shock when an external shock is applied, and the protection tube is provided. 8 has a structure in which the fusion-stretched portion 7 inside is hardly damaged or broken.

FIG. 2 shows a second embodiment of the present invention. FIG. 2 (a) is a plan view, and FIG.
It is the partial side sectional view cut | disconnected along the broken line BB shown to (a). The feature of this embodiment is that a housing 21 is used, and an optical fiber coupler body 10a is housed in a housing 21c inside the housing 21.
The difference is that the buffer material 22 composed of the first buffer material 22a and the second buffer material 22b having a symmetrical structure is filled around 0a. These first cushioning material 22a and second cushioning material 22b
Has the same shape as the shape of the first buffer material 12a and the second buffer material 12b shown in FIG. In other words, of the optical fiber coupler protection structure shown in FIG.
Are housed in a housing 21.

The housing 21 comprises a main body 21a and a cover 21b obtained by dividing the housing 21 into two parts. An optical fiber coupler body 10a is housed in a housing portion 21c inside the housing 21 composed of the main body 21a and the cover 21b. Around the optical fiber coupler body 10a, a first buffer material 22a having a symmetric structure and a second The buffering material 22b is the optical fiber coupler body 1
0a is filled. The first buffer member 22a and the second buffer member 22b are stacked so as not to contact each other with the optical fiber coupler body 10a interposed therebetween. These first cushioning material 22a and second cushioning material 2
On the surface facing 2b, grooves 22c and 22d are provided in the longitudinal direction of the optical fiber coupler body 10a, respectively, so that the optical fiber coupler body 10a is sandwiched and positioned and held. Has become. Also,
The arrangement distance d2 between the first buffer material 22a and the second buffer material 22b is about 1 mm.

In the housing 21, port openings 21e, 21e are provided on both side surfaces of the optical fiber coupler main body 10a so as to open to the outside from the storage portion 21c.
Ports 9a and 9b and ports 9c and 9d extend from here. Then, the four screws 23 penetrating the cover 21b and the main body 21a in this order are integrated with each other to form the housing 21.
a, the first cushioning member 22a and the second cushioning member 22b are fixed via the cover 21b in the storage portion 21c with the optical fiber coupler body 10a interposed therebetween, and further attached to the mounting plate 24 provided on the outer surface of the body 21a. It is assembled.

The housing 21 is made of metal or the like and has a certain level of mechanical strength. The length of the housing 21 is 64 m
m, the width is 16 mm, and the height is 11 mm. Body 21
accommodating part 21 in which a and cover 21b are integrally formed
The length, width and height of c are 60 mm, 10 mm and 7 respectively.
mm.

The first cushioning member 22a and the second cushioning member 22b
Is made of a rubber-like elastic material and has a Young's modulus of 1 to 10 kg / m.
Those having a size of about m ² are preferred. For example, natural rubber, synthetic rubber, or the like can be used. Or various synthetic resins,
For example, a sponge (porous synthetic resin) made of polyurethane or the like can be used. Also, the first cushioning material 2
2a has a length of 60 mm and a width of 10 mm. The thickness t2 of the first cushioning member 22a is 3 mm. The groove 22
c has a width of 3.2 mm and a depth of 1.6 mm.
These sizes are the same for the second cushioning member 22b and the groove 22d.

The first cushioning member 22a and the second cushioning member 22
Although b may be adhered to the inside of the storage portion 21c, it is preferable that it is not adhered because the degree of freedom is high. Further, in the above-described embodiment, the length and width of the first cushioning member 22a and the second cushioning member 22b are set to correspond to the length and width of the storage portion 21c, but are set smaller than this. You can also. That is, the optical fiber coupler 10a may be provided only in the vicinity of the center in the longitudinal direction of the optical fiber coupler 10a, as long as it is provided in a range that can protect the optical fiber coupler main body 10a. The housing 21 (the main body 21)
a, the cover 21b) and the size of the cushioning material 22 (the first cushioning material 22a and the second cushioning material 22b) can be appropriately changed depending on the size of the 2 × 2 type optical fiber coupler 10 to be protected.

In the second embodiment, the first cushioning member 22a and the second cushioning member 22b are laminated without being in contact with each other.
By adjusting the thickness of the groove 2b and the depth of the groove 22c and the groove 22d, the first cushioning material 22a and the second cushioning material 2a are adjusted.
On the surface facing the surface 2b, the grooves 22c and 22d may be designed to be in contact with the outside of the grooves 22d. However, the first cushioning material 22
a, the degree of freedom with the second buffer material 22b is increased, and the buffer effect can be improved.

The cross-sectional shape of the grooves 22c and 22d is not limited to a V-shape, but can be changed to a U-shape or the like as appropriate. However, if the optical fiber coupler body 10a is formed in a semicircular shape in close contact with the outer periphery thereof, the optical fiber coupler body 10a
And the contact area between the groove 22c and the groove 22d is increased, and the degree of freedom of the optical fiber coupler body 10a in the length direction is reduced. Therefore, a shape in which the contact area is reduced, such as a V-shape, is selected. Is preferred.

The mounting plate 24 is provided so that the 2 × 2 type optical fiber coupler 10 can be easily mounted on optical equipment, but is not essential. When the mounting plate 24 is not provided, the main body 21a and the cover 2 are
What is necessary is just to fix only 1b. The length of the mounting plate 24 is 73 mm, the width is 23 mm, and the thickness is 3 mm.

In the optical fiber coupler protection structure according to the second embodiment, since the mechanical strength is obtained by the housing 21, the buffer 22 is made to have a Young's modulus smaller than that of the buffer 12 used in the first embodiment. Of a soft material having a small particle size. As described above, the cushioning effect can be enhanced by the cushioning member 22 made of a soft material, and the outer casing can obtain the mechanical strength of the housing 21, so that the strength against the external impact can be further enhanced as compared with the first embodiment. it can.

FIG. 3 shows a third embodiment of the present invention. FIG. 3 (a) is a plan view, and FIG.
FIG. 4 is a partial side sectional view taken along a broken line CC shown in FIG. Housing 31, main body 31a, cover 31b, storage unit 3
1c, port port 31e, screw 33, and mounting plate 34 are as shown in FIG.
, Body 21a, cover 21b, storage unit 21
c, the port opening 21e, the screw 23, and the mounting plate 24. The third embodiment differs from the second embodiment shown in FIG. 2 in that three buffer members are provided along the length of the optical fiber coupler main body 10a housed in the housing portion 31c of the housing 31 along the length direction. 32 is a point arranged at intervals. These cushioning members 32 are disposed near both ends and near the center of the optical fiber coupler body 10a.

The cushioning member 32 has a first symmetrical structure.
It consists of a member 32a and a second member 32b. The first member 32a and the second member 32b are provided with a groove 32c and a groove 32d having a V-shaped cross section, respectively. That is, the grooves 32c and 32d are in contact with the outer peripheral surface of the optical fiber coupler body 10a, so that the optical fiber coupler body 10a
Are sandwiched and supported by the first member 32a and the second member 32b. The first member 32a and the second member 32b are stacked so as not to contact each other with the optical fiber coupler body 10a interposed therebetween. The arrangement interval d3 is about 1 mm.

The cushioning member 32 is preferably made of a rubber-like elastic material and has a Young's modulus of about 1 to 10 kg / mm ² . For example, natural rubber, synthetic rubber, or the like can be used. Alternatively, various synthetic resins, for example, a sponge (porous synthetic resin) made of polyurethane or the like can be used. In the first member 32a, the depth of the groove 32c is 1.6 mm, and the width is 3.2 mm. The length L3 of the first member 32a is 10 mm and the width is 10 mm. The thickness t3 of the first member 32a is 3 mm. These sizes are the same for the second member 32b and the groove 32d. In the length direction of the optical fiber coupler body 10a, the distance L4 between the buffer members 32 is 8 mm, and the distance L5 from the end edge of the protective tube 8 to the buffer member 32 at the end is 2 m.
m.

The cross-sectional shapes of the grooves 32c and 32d are not limited to the V-shape as long as the optical fiber coupler body 10a can be supported, and may be a U-shape or the like. However, if the optical fiber coupler body 10a is formed in a semicircular shape or the like which is in close contact with the outer periphery of the optical fiber coupler body 10a, the first member 32
a, the contact area between the first member 32a and the second member 32b increases, and the degree of freedom in the length direction of the optical fiber coupler body 10a decreases. Therefore, a shape in which the contact area decreases, such as a V-shape, should be selected. Is preferred. In addition, the first cushioning material 3
2a and the second cushioning material 32b are laminated without being in contact with each other, but the first cushioning material 32a and the second cushioning material 32b
By adjusting the thickness of the first member 32a and the depth of the groove 32d, etc., the first member 32a and the second member 32b are designed to be in contact with each other outside the groove 32c and the groove 32d on the facing surface. You may. However, the first member 32a, the second member 3
The degree of freedom with respect to 2b is increased, and the buffering effect can be improved. In addition, the number of the cushioning members 32 may be two or more, and is substantially about 2 to 5, preferably about 3 to 4. The housing 31 (the main body 31a, the cover 31)
b), cushioning material 32 (first member 32a, second member 32b)
And the arrangement interval of the buffer material 32 can be appropriately changed as long as the buffering effect can be obtained while supporting the optical fiber coupler body 10a.

As described above, in the optical fiber coupler protection structure of the third embodiment, a plurality of cushioning members 32 are arranged at intervals in the storage portion 31c in the housing 31, and the optical fibers are separated by the cushioning members 32. Since the coupler body 10a is supported, the shock-absorbing effect is further improved as compared with the structure using one cushioning material 22 as in the second embodiment shown in FIG. In addition, housing 3
Since 1 has mechanical strength, similarly to the second embodiment, the buffer material 32 can be made of a relatively soft material having a high buffering effect. For this reason, the buffer effect can be further enhanced, and at the same time, the mechanical strength can be obtained by the housing 31, so that the strength of the protective structure can be further improved.

Although the first to third embodiments described above relate to a 2 × 2 type optical fiber coupler, the present invention is not limited to this, and the same applies to other M × N type optical fiber couplers. Needless to say, it can be applied to

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical fiber coupler according to a first embodiment (embodiment 1), a second embodiment (embodiment 2), and a third embodiment (embodiment 3) shown in FIGS. Protective structures were prepared and subjected to an impact test to check the strength. As a comparative example, a test was also performed on a structure having no buffer material around the optical fiber coupler body 10a shown in FIG. At this time, the material of the cushioning material of Example 1 was silicone RT having a Young's modulus of 7 kg / mm ² .
V rubber was used. Silicone RTV rubber having a Young's modulus of 1 kg / mm ² was used as the material of the cushioning material of Example 2.
The material of the cushioning material of Example 3 is a Young's modulus of 1 kg / mm.
^Two silicone RTV rubbers were used.

Each of Examples 1 to 3 and Comparative Example was 5
Each sample was dropped on a concrete surface at a different height. After falling, light was incident on the optical fiber coupler. The emitted light at this time was measured with a power meter, and it was determined that breakage occurred in the fusion-stretched portion (optical branching / coupling portion) when the light was no longer emitted. At this time, in each of Examples and Comparative Examples, an accelerometer was previously attached to the attachment plate, and the impact acceleration when a break occurred was measured. Table 1 shows the results. Table 1
The average impact acceleration shown in Fig. 7 shows the average value of the impact acceleration in each of the five samples.

[0038]

[Table 1]

From Table 1, it was confirmed that in Examples 1 to 3 according to the present invention, breakage was less likely to occur than in Comparative Examples in which no cushioning material was provided. In addition, the strength was increased in the order of Examples 1 to 3, and it was confirmed that the strength was improved by using the housing and the soft cushioning material, and that the strength was further improved by disposing the cushioning material at intervals. .

[0040]

According to the first aspect of the present invention, a cushioning material is provided around the optical fiber coupler body (protective tube).
The shock absorbing material absorbs an external impact, and it is possible to prevent the fusion-stretched portion (optical branching portion) inside the protective tube from being damaged or broken.

According to the second aspect of the present invention, the optical fiber coupler body is housed in the housing, and a buffer is provided around the optical fiber coupler body (protective tube).
The housing provides mechanical strength, and the cushioning member can be made of a soft material having a relatively small Young's modulus.
In this way, the cushioning material made of a soft material enhances the buffering effect, and the outer casing has the mechanical strength of the housing, so that the strength against external impact can be further increased.

In the third invention, the optical fiber coupler main body is housed in the housing, and a plurality of buffer members are provided around the optical fiber coupler main body (protective tube) at intervals in the length direction. And the buffer effect is further improved.

[Brief description of the drawings]

FIG. 1 is a first diagram illustrating a protection structure of an optical fiber coupler according to the present invention.
FIG. 1 (a) is a plan view,
FIG. 1B is a partial side cross-sectional view taken along a broken line AA shown in FIG.

FIG. 2 shows a second embodiment of the present invention,
2A is a plan view, and FIG. 2B is a partial side sectional view taken along a broken line BB shown in FIG. 2A.

FIG. 3 shows a third embodiment of the present invention,
FIG. 3A is a plan view, and FIG. 3B is a partial side cross-sectional view taken along a broken line CC shown in FIG.

FIG. 4 is a plan view showing an example of a method of manufacturing a 2 × 2 type optical fiber coupler in the order of (a) to (d).

[Explanation of symbols]

Reference numeral 8: protective tube, 9a, 9b, 9c, 9d: port (optical fiber), 10a: optical fiber coupler body, 12: cushioning material, 21: housing, 22: cushioning material, 31: housing, 32: cushioning material

Continued on the front page (72) Inventor Ryozo Yamauchi 1440 Musaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Factory

Claims (3)

[Claims] 1. A protective structure for an optical fiber coupler, wherein a buffer material is provided around the optical fiber coupler body. 2. A protective structure for an optical fiber coupler, wherein a buffer is provided around an optical fiber coupler body in a housing. 3. A protection structure for an optical fiber coupler, wherein a plurality of cushioning members are arranged around the optical fiber coupler main body in the housing at intervals in the longitudinal direction of the optical fiber coupler main body.