JP3215098B2 - Optical attenuating fiber assembly and optical attenuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel optical attenuating fiber set manufactured using an optical fiber having a certain optical attenuation characteristic by intentionally doping impurities into the optical fiber. About three-dimensional. More specifically, a light capable of giving an accurate constant amount of light attenuation value even when using an optical attenuation fiber which is difficult to manufacture by controlling the light attenuation value precisely for a predetermined length. The present invention relates to an attenuation fiber assembly and an optical attenuator using the assembly.

[0002]

SUMMARY OF THE INVENTION The present inventor has manufactured a connector type or an attenuator connectable to a connector using an optical fiber having a considerable attenuation per unit length by doping the impurities described above. Tried. 8 is a sectional view showing the connector type optical attenuator, and FIG. 9 is a sectional view showing a ferrule assembly of the optical attenuator. A through-hole 2 is provided at the center of the cylindrical ferrule 1 of the ferrule assembly of the optical attenuator shown in FIG. 9, and the optical attenuation fiber 3 is inserted and bonded into the through-hole 2.
A flange 4 is fixed to the outer periphery of the ferrule 1,
The flange 4 serves to regulate the position of the ferrule assembly in the axial and circumferential directions. The plug housing 5 is formed from main body parts 5A and 5B, and an alignment sleeve 7 is provided in the part 5A. One end of the cylindrical ferrule 1 of the ferrule assembly is aligned with the alignment sleeve 7.
And is coupled to 5A in a state where the rotation of the flange 4 is prevented by the component 5B. The coupling nut 6 is provided rotatably around the plug housing 5. By coupling the ferrule of another optical fiber connector (not shown) to the other end of the alignment sleeve 7, an optical fiber plug having an attenuator at the tip is formed.

If the axial length L of the ferrule 1 is constant and the optical attenuation value per unit length of the optical attenuation fiber is A decibel, an L × A decibel attenuator is formed. The optical attenuation value of the optical attenuator is generally 3, 5, 1
0, 15, and 20 dB are required as standard, and 8 ± 0.8 dB and 13 ± 1.3 depending on the application.
Any intermediate value, such as decibels, may be required.
In this case, there is a problem if the optical attenuation value per unit length of the optical fiber of the type described above varies or has an error. For example, if the desired optical attenuation value is 20 ± 2 dB with the axial length L of the ferrule 1 = 20 mm, the optical attenuation fiber must be manufactured so that the error of the optical attenuation value A per unit length is within ± 10%. Must. However, in order to stably manufacture with the current optical attenuation fiber manufacturing technology, the attenuation value error is about A ± 20%. Therefore, this L = 20 mm
In this case, the optical attenuation value error is as large as 20 ± 4 dB, and the standard value cannot be satisfied. If A with optical attenuation fiber
If sorting is performed so as to satisfy ± 10%, occurrence of a large defective rate cannot be avoided. Since it is difficult to adjust the length of the ferrule 1 individually, it is necessary to inspect and select only the acceptable optical attenuating fiber and use it, which inevitably increases the cost.

[0004] The optical attenuating fiber attempts to absorb light by doping impurities such as Co and Cr into the silicon glass of the ordinary optical fiber. However, it is not easy to control the manufacturing process, and the unit length is short. It is extremely difficult to obtain a desired attenuation characteristic per hit. However, it is known that substantially uniform attenuation characteristics can be obtained in a single lot. SUMMARY OF THE INVENTION An object of the present invention is to provide an optical attenuating fiber assembly that can provide a desired arbitrary attenuation using an optical attenuating fiber. It is still another object of the present invention to provide an optical attenuator using the optical attenuation fiber assembly.

[0005]

In order to achieve the above object, an optical attenuating fiber assembly according to the present invention comprises an optical attenuating fiber having a length providing a desired amount of attenuation, and a fusion spliced to one end of the optical attenuating fiber. A first ferrule having a small through hole and a stepped hole for receiving and fixing the tip of the light attenuating optical fiber,
A second ferrule having a small through hole and a stepped hole for receiving and fixing the tip of a normal optical fiber connected to one end of the optical attenuation fiber by fusion, the first ferrule and the second ferrule, And an alignment sleeve for aligning and fixing. In the optical attenuating fiber assembly, the end surfaces of the first and second ferrules are polished, preferably polished with inclined spherical surfaces. In the optical attenuation fiber assembly, the alignment sleeve may include a flange. The optical attenuator according to the present invention includes a plug housing, another alignment sleeve housed in the plug housing, and the second ferrule portion whose rotation is restricted by the flange portion in the plug housing, The light attenuating fiber assembly engaged with the other alignment sleeve.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings and the like. FIG. 4 is a sectional view showing an embodiment of an optical attenuation fiber assembly (FA) according to the present invention. FIG. 1 is a sectional view showing a fusion-bonding process of the embodiment of the optical attenuation fiber assembly (FA). FIG. 2 is a cross-sectional view showing the optical attenuation fiber assembly (F) connected in the fusion step. FIG. 3 is a sectional view showing an assembling process of an embodiment of an optical attenuation fiber assembly (FA) using the optical attenuation fiber assembly (F). As shown in FIG. 1, each end face 11, 12 of the optical attenuating fiber 9 and the ordinary optical fiber 10 are butted and fused by a discharge arc 13.
Optical attenuation fiber 9 as shown in FIG. 2 is cut at the position of the length L ₂ which is a required optical attenuation. Then, the ordinary optical fiber 10 is also cut into an appropriate length to form an optical attenuation fiber assembly (F). At the center of the cylindrical ferrule 16, as shown in FIG. 3, a minute through hole 14 and a stepped hole 15 that precisely receive the tip of the optical attenuation fiber 9.
Is provided. The cylindrical alignment sleeve 19 is provided with a through hole 18 into which the ferrule outer diameter surface 17 of the ferrule 16 is inserted.
Is inserted and bonded over the middle of the axial length of the. The optical attenuation fiber 9 of the optical attenuation fiber assembly (F) is
The first ferrule 16 is inserted into and adhered to the center minute through hole 14. The reason why two ferrules are used in the optical attenuating fiber assembly of the present invention is that the center of each ferrule is deviated and deformed due to the displacement (eccentricity) and deformation of the optical axis at the fusion splicing point between the optical attenuating fiber and the ordinary optical fiber. This is due to the inability to insert into the minute through-hole.

The ordinary optical fiber 10 has a second ferrule 2 having substantially the same shape as the first ferrule 16.
Inserted and fixed at 0. As shown in FIG. 4, the ordinary optical fiber 10 is connected to the small through hole 2 at the center of the second ferrule 20.
At the same time, the outer diameter surface 22 of the second ferrule 20 is inserted and adhered to the alignment sleeve hole 18. Thereafter, the ferrule end surfaces 23 and 24 are polished.
As a result, an optical attenuation fiber assembly (FA) is obtained.

FIG. 5 shows the optical attenuation fiber assembly (F) described above.
A) is the plug housing (P
It is sectional drawing which shows the Example of the optical attenuator formed by incorporating in H). The ferrule 20 on the normal optical fiber side of the optical attenuation fiber assembly (FA) is a plug housing (PH).
And the flange 19a of the alignment sleeve 19 of the optical attenuating fiber assembly (FA) is inserted into the alignment sleeve 7 (another alignment sleeve).
H) is held between the body parts 5A and 5B with rotation restricted. By connecting the optical fiber lines from the directions indicated by arrows A and B in the figure, an attenuator can be inserted into the optical fiber line.

FIG. 6 is a sectional view showing another embodiment of the optical attenuation fiber assembly according to the present invention. In this embodiment, the optical attenuating fiber assembly (F) is formed from an optical attenuating fiber 9 and a normal optical fiber 10, and its manufacturing method is as described with reference to FIGS.
The ferrule 116 has a thin tip, and has a hole for receiving and supporting an optical fiber and a stepped hole 118 connected to the inside thereof.
Accept and fix the tip of Similarly, the ferrule 120 also has a thin tip, has a hole for receiving and supporting an optical fiber and a stepped hole 123 connected to the inside, and receives and fixes and fixes the distal end of the normal optical fiber 10 in the hole for receiving and supporting the optical fiber. I have. Each ferrule 116 and 12
Numeral 0 is inserted and fixed in a sleeve 119 having a flange 119a. Tip 12 of each ferrule 116 and 120
The end surfaces of 5 and 126 are inclined surfaces of θ = 8 degrees or more with respect to the plane perpendicular to the optical axis, and are polished to spherical surfaces.

FIG. 7 is a sectional view showing a reference example in which an optical attenuation fiber assembly (F) is incorporated in an optical connector ferrule. The optical attenuation fiber 33 is connected to the optical fiber portion 34 from which the normal optical fiber coating portion 31 has been removed by discharge arc fusion. The optical attenuating fiber 33 is shown in FIG.
One end is cut slightly longer than the length shown in ₂ . The optical fiber coating portion 31 is inserted and fixed in the hole 32 of the flanged cylinder 30 having the flange 30A. The connection point between the optical attenuation fiber 33 and the ordinary optical fiber 34 is in the stepped hole. The reason for this is that there is a possibility that the optical fiber cannot be inserted into the center minute through-hole of each ferrule due to the displacement (eccentricity) and deformation of the optical axis at the fusion splicing point between the optical attenuation fiber and the ordinary optical fiber. Flanged cylinder 30
A stepped hole is provided on the flange side of the hole 32 of
The base of the ferrule 27 is inserted and fixed in this hole.
The tip of the optical attenuation fiber 33 and the tip of the ferrule are polished simultaneously. This assembly is used as an optical connector having an optical attenuation function.

As described above, it is difficult to stably manufacture an optical attenuation fiber having a predetermined optical attenuation value per unit length. However, the optical attenuator using the optical attenuating fiber of the present invention produces an optical attenuating fiber assembly having an accurate optical attenuating value even if an optical attenuating fiber having a large optical attenuating value error during manufacturing is used. it can. Also, various types of optical attenuation fiber assemblies having arbitrary optical attenuation values can be easily manufactured. Only the length of the optical attenuation fiber is adjusted, and there is no need to change the length of other components, such as a ferrule, for adjusting the attenuation.

Various modifications can be made to the embodiment described in detail above within the scope of the present invention. In addition to the above-described embodiment, the present invention can be incorporated in an optical device or the like that requires an optical attenuation function.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a fusion step of an embodiment of an optical attenuation fiber assembly according to the present invention.

FIG. 2 is a cross-sectional view showing an optical attenuation fiber assembly connected by the fusion process shown in FIG.

FIG. 3 is a cross-sectional view showing an assembling process of an embodiment of the optical attenuation fiber assembly using the optical attenuation fiber assembly shown in FIG. 2;

FIG. 4 is a sectional view showing an embodiment of an optical attenuation fiber assembly according to the present invention manufactured through the assembly process shown in FIG. 3;

FIG. 5 is a sectional view showing an embodiment of an optical attenuator in which the optical attenuation fiber assembly shown in FIG. 4 is incorporated in a plug housing.

FIG. 6 is a sectional view showing another embodiment of the optical attenuation fiber assembly according to the present invention.

FIG. 7 is a cross-sectional view showing another reference example in which the optical attenuation fiber assembly of the present invention is incorporated in an optical connector ferrule.

FIG. 8 is a sectional view for explaining a problem of an optical attenuator manufactured by incorporating only an optical attenuation fiber into a single-core optical fiber connector.

FIG. 9 is a sectional view showing a ferrule assembly of the optical attenuator shown in FIG.

[Explanation of symbols]

 1, 16, 20, 27, 116, 120 Ferrule 2, 8, 14, 18, 21, 28 Through hole 3, 9, 33 Optical attenuation fiber 4 Flange 5 Plug housing 6 Coupling nut 7, 19, 119 Alignment sleeve 10 , 34 Normal optical fiber 23, 24 End face 13 Discharge arc 15, 29, 118, 123 Stepped hole 30 Flanged cylinder 31 Optical fiber coating 32 Flanged cylinder inner diameter 125, 126 End face (spherical surface)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-334649 (JP, A) JP-A-63-313102 (JP, A) JP-A-54-2754 (JP, A) 15002 (JP, U) JP-A-63-96506 (JP, U) JP-A-63-96504 (JP, U) JP-B-61-19001 (JP, B2) US Patent 5388885 (US, A) US Patent 5109468 (US, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/00 G02B 6/38 G02B 6/26 G02B 6/36 G02B 5/20

Claims (4)

(57) [Claims] 1. A light-attenuating fiber having a length that provides a desired attenuation, a normal optical fiber connected to one end of the light-attenuating fiber by fusion, and a microscopic member for receiving and fixing the tip of the light-attenuating optical fiber. A first ferrule having a through hole and a stepped hole; and a second ferrule having a small through hole and a stepped hole for receiving and fixing the tip of a normal optical fiber connected to one end of the optical attenuation fiber by fusion. And an alignment sleeve for aligning and fixing the first ferrule and the second ferrule. 2. The optical attenuating fiber assembly according to claim 1, wherein said first and second ferrule end faces are polished, preferably slanted spherical polished. 3. The light attenuating fiber assembly according to claim 2, wherein said alignment sleeve comprises a flange. 4. A plug housing, another alignment sleeve housed within the plug housing, and a rotation limited at the flange portion within the plug housing, wherein the second ferrule portion is the other alignment sleeve. An optical attenuator comprising: the optical attenuating fiber assembly according to claim 3, wherein