JPH077136B2 - Optical fiber coupler - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical fiber coupler for branching or joining light in optical communication, an optical fiber sensor, or the like.

"Prior Art and its Problem" Conventionally, as one of the optical fiber couplers used for the above-mentioned purpose, the one shown in FIGS. 6 and 7 is known. The optical fiber coupler 1 shown in this figure includes a polishing optical fiber 5 formed by polishing and removing the clad portion 2 of a part of the optical fiber to form a polishing surface 4 in which a portion near the core 3 is exposed. Two polishing substrates 8 consisting of a grooved substrate 7 in which a fiber 5 is embedded in a groove 6 and fixed with the polishing surface 4 facing upward are used, and the polishing surfaces of each of these polishing substrates 8 and 8 are used. 4, 4 and 4 are contacted to form a contact portion 9. The polishing optical fiber 5 is a groove 6 of the grooved substrate 7.
It is fixed inside by an adhesive 10.

The optical fiber coupler 1 includes the respective polishing optical fibers 5,
At the contact portion 9 where the cores 3 and 3 of 5 are close to each other, the optical power guided through the polishing optical fiber 5 is branched and merged so that the optical power is coupled.

By the way, the polishing substrate 8 is prepared as follows. First, as shown in FIG. 8, the portion of the optical fiber 11 from which the coating 12 has been removed is inserted into the groove 6 of the grooved substrate 7. This groove 6
Is formed in an arc shape so that it is shallow at the center of the grooved substrate 7 and gradually becomes deeper at both ends. Next, an adhesive is injected into the groove 6 to solidify it. Thereby, the optical fiber 11 is fixed in the groove 6 of the grooved substrate 7. Next, the surface of the grooved substrate 7 on the groove 6 side is polished and removed by a predetermined dimension to expose a part of the optical fiber 11 near the core 3.

In the thus-prepared polishing substrate 8, breakage of the polishing optical fiber 5 easily occurs at both ends of the groove 6,
Therefore, as shown in FIG. 9, adhesive 13,1 is applied to both ends of the groove 6.
3 was applied to protect the polished optical fiber 5.

However, the adhesive 13 provided on both ends of the groove 6 is
Since the adhesive area with the polishing substrate 8 is small and the adhesive force is weak, there is a problem that the abrasive optical fiber 5 is likely to be peeled off and cut.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fiber coupler having high mechanical strength, which is unlikely to cause inconveniences such as cutting of a polished optical fiber.

"Means for Solving the Problem" The present invention relates to a polished optical fiber in which a clad portion is polished and removed in a part of an optical fiber to form a polished surface exposing a core vicinity portion, and the polished optical fiber. And a grooved substrate which is embedded in the groove and is fixed with the polishing surface facing upward. Two polishing substrates are used, and the polishing surfaces of these polishing substrates are contacted to form a contact portion. In the optical fiber coupler for coupling the optical power at the contact portion, the grooved substrate has a width capable of accommodating a polishing optical fiber coating at both ends of the groove, and from the upper surface to the lower surface of the grooved substrate. A means for solving the problem was to form an extended portion penetrating up to the point where the coated portion of the polishing optical fiber was put in the extended portion and fixed to the grooved substrate with an adhesive.

"Function" Since the expanded portions having the expanded groove size are formed at both ends of the groove of the grooved substrate, when the optical fiber is fixed in the groove, an adhesive is injected into the expanded portion so that the optical fiber By fixing the portions located at both ends of the groove, the adhesive area of the adhesive for fixing the portions is increased, and peeling of the adhesive is prevented.

"Embodiment" FIG. 1 is a view showing an embodiment of the present invention, which is designated by reference numeral 14
Is an optical fiber coupler. This fiber optic coupler 14
Is a polishing optical fiber 5 formed by polishing and removing the clad portion 2 of a part of the optical fiber 11 to expose a portion near the core 3, and the polishing optical fiber 5 in the groove 6. Two polishing substrates 16 consisting of a grooved substrate 15 which is embedded and fixed with the polishing surface facing upward are used, and the polishing surfaces 17 and 17 of these polishing substrates 16 and 16 are brought into contact with each other to make contact. It is configured by forming a part 18.

As the optical fiber 11, a normal optical fiber used for optical communication or the like, for example, a single mode optical fiber made of a silica-based or multi-component glass or plastic material, a multi-mode optical fiber, a stress imparting polarization-maintaining light Fiber etc. can be used. Also in this example, the optical fiber
As 11, there is used an optical fiber bare wire in which a bare optical fiber is coated with at least one layer.

As shown in FIG. 2, the grooved substrate 15 has expanded portions 19 and 19 formed by expanding the size of the groove 6 at both ends of the groove 6. These extensions 19 and 19 cover the optical fiber 11 with a coating 12
Is set to a size such that the optical fiber 11 can be inserted into the groove 6, and when the optical fiber 11 is embedded in the groove 6, the portion of the optical fiber 11 from which the coating 12 is removed is inserted into the groove 6 and the end portion of the coating 12 is expanded. It can be inserted into the part 19. This groove 6 and extension
The optical fiber 11 inserted in 19, 19 is fixed by an adhesive 20. As a material for the grooved substrate 15, a hard transparent material such as quartz glass, multi-component glass, or fluoride glass is used, and particularly the same material as the material forming the optical fiber 11 is preferably used.

In this optical fiber coupler 14, optical power is branched or merged at the contact portion 18 where the cores 3 of the two polishing optical fibers 5 are close to each other. For example, when optical power is incident on the core 3 on the incident side of one of the polishing optical fibers 5, this optical power is
Part of it leaks to the other polished optical fiber 5 side at the contact portion 18,
The optical power is made incident on the core 3, and as a result, optical power branched from the output side of one polishing optical fiber 5 and the branch output side of the other polishing optical fiber 5 with a predetermined coupling ratio is obtained.

The optical fiber coupler 14 is manufactured as follows. First, a substrate made of a transparent material such as quartz glass is appropriately ground to form an arc-shaped groove 6 having a shallow central portion and deep end portions.
And extending portions 19 and 19 having a size capable of inserting the coating 12 of the optical fiber 11 are formed at both ends of the groove 6, and
The grooved substrate 15 is as shown in the figure.

Next, the optical fiber 11 is inserted into the groove 6 of the grooved substrate 15. In this optical fiber 11, the coating 12 on the part to be inserted into the groove 6 is removed. And the coating of this optical fiber 11
The portion from which 12 has been removed is inserted into the groove 6, and both ends of the coating 12 are inserted into the expanded portions 19 and 19. Next, the groove 6 and the extension 1
The adhesive 20 is filled in the 9,19 and solidified. As a result, the optical fiber 11 is formed so that the groove 6 of the grooved substrate 15 and the extension portion
Fixed within 19,19.

Next, the surface on the side facing the groove 6 side is fixed to a holding jig of a polishing device, and the surface on the groove 6 side is polished until a predetermined polishing amount is obtained. By this polishing operation, a part of the optical fiber 11 fixed in the groove 6 is removed by polishing to the vicinity of the core 3 to become the polished optical fiber 5, and the grooved substrate 15 is polished on the surface on the groove 6 side. It becomes the polishing substrate 16 with the polishing surface 4 of the fiber 5 exposed.

Next, the two polishing substrates 16 prepared as described above are superposed so that the polishing surfaces 17 of the respective polishing optical fibers 5 are in contact with each other, and a matching liquid is interposed between the respective polishing surfaces 17, Join using an adhesive or the like. By the above operation, the optical fiber coupler 14 having the structure shown in FIG. 1 is manufactured.

The optical fiber coupler 14 according to this example includes the groove 6 of the grooved substrate 15.
Since the expanded portions 19 and 19 in which the size of the groove 6 is expanded are formed at both ends of the groove 6, when the optical fiber 11 is fixed in the groove 6, the adhesive 20 is injected into the expanded portions 19 and 19, Groove 6 of optical fiber 11
By fixing the parts located at both ends of the adhesive
It is possible to increase the adhesion area of the adhesive 20 and make it difficult for the adhesive 20 to be peeled off, and to prevent the abrasive optical fiber 5 from being cut due to the peeling of the adhesive.

Further, as the optical fiber 11, an optical fiber element wire having at least one layer of coating is used, and the extended portions 19 and 19 are covered with this coating 12.
Since the size is set so that the groove can be inserted, the groove 6 of the grooved substrate 15
When fixing the optical fiber 11 inside, cover 12 of the optical fiber 11
By inserting the removed portion into the groove 6 and inserting both ends of the coating 12 into the expanded portions 19 and 19 and fixing with the adhesive 20,
The effect of preventing the cutting of the optical fiber 11 can be further enhanced.

In the above-mentioned optical fiber coupler 14, the expansion portion 19 is formed as shown in FIG. That is, the rotating cemented carbide blade 21 is moved downward at both ends of the groove 6 in the substrate on which the groove 6 is formed, as shown by the arrow in FIG.

(Production example) As an optical fiber, core diameter 8μm, clad diameter 125μm
An optical fiber strand having an outer diameter of 400 μm provided with a thermosetting resin coating was used for the silica single mode optical fiber of (3).

As a grooved substrate, a glass block having a width of 5 mm, a thickness of 5 mm, and a length of 20 mm is provided with a groove having a width of 200 μm and a depth of 200 μm, and a groove-shaped expanded portion having a width of 1 mm and a length of 5 mm at both ends of the groove. Was used.

The coating of the optical fiber was removed over 13 mm, and this coating removal portion was inserted into the groove of the grooved substrate. Then, both ends of the coating of the optical fiber were positioned at the centers of the respective expanded portions, and then an epoxy adhesive was injected into the groove and the expanded portions to solidify them. Next, the groove-side surface of this grooved substrate was polished to 125 μm to 133 μm to obtain a polished substrate.

Next, the two polishing substrates prepared as described above were superposed so that their respective polishing surfaces were in contact with each other, and a matching liquid was interposed therebetween, and then the respective substrates were bonded. Through the above operation, an optical fiber coupler having the same structure as that shown in FIG. 1 was manufactured.

In this optical fiber coupler, the coating of the polished optical fiber was firmly fixed in a state where it was inserted into the expanded portion, and no sign of peeling of the adhesive at both ends of the groove was observed.

[Advantages of the Invention] As described above, the optical fiber coupler according to the present invention has a width capable of accommodating the coating of the polishing optical fiber at both ends of the groove of the grooved substrate and from the upper surface to the lower surface of the grooved substrate. Since the extended portion penetrating to the groove is formed, when the optical fiber is fixed in the groove, the adhesive is injected into the extended portion and the portions located at both ends of the groove of the optical fiber are fixed. It is possible to increase the adhesive area of the adhesive and prevent the adhesive from peeling off, and to prevent the abrasive optical fiber from being cut due to the peeling of the adhesive.

Furthermore, the adhesive portion can be accommodated in the expansion portion, the length in the longitudinal direction of the optical fiber coupler can be shortened, and miniaturization can be achieved. Conventional fiber optic couplers are long only at the adhesive.

Furthermore, when an optical fiber having at least one layer of coating is used and the expansion portion is set to a size such that this coating can be inserted, when fixing the optical fiber in the groove of the grooved substrate, By inserting the portion from which the coating has been removed into the groove and inserting both ends of the coating into the expansion portion and fixing them with an adhesive, the effect of preventing the abrasive optical fiber from being cut can be further enhanced.

Furthermore, in the present invention, by using a grooved substrate having a width capable of accommodating the coating of the polishing optical fiber at both ends of the groove and having an extended portion penetrating from the upper surface to the lower surface of the grooved substrate, Put the coating removal part of the optical fiber in the groove of this grooved substrate and put the optical fiber coating part in the extension part,
When the adhesive is injected into the groove and the expanded portion and solidified to fix the optical fiber, the adhesive can be injected from both the upper side and the lower side of the expanded portion to solidify the optical fiber. It can be done reliably.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an optical fiber coupler according to the present invention. FIG. 1 is a side view of the optical fiber coupler, and FIG. 2 is a plan view of a grooved substrate used in the optical fiber coupler of FIG. FIGS. 3 and 4 are views showing a polishing substrate used in the optical fiber coupler shown in FIG. 1. FIG. 3 is a side view of the polishing substrate, FIG. 4 is a plan view of the same, and FIG. 5 is a groove. FIG. 6 is a schematic side view for explaining an example of a method of forming an extension portion on a substrate with a substrate, FIGS. 6 and 7 are views showing a conventional optical fiber coupler, and FIG. 6 is a side view of the optical fiber coupler. ,
FIG. 7 is a cross sectional view of a portion A in FIG. 6, FIG. 8 and FIG.
FIGS. 8A and 8B are views for explaining a manufacturing process of the same conventional optical fiber coupler. FIG. 8 is a perspective view showing a state where an optical fiber is inserted into a groove of a grooved substrate, and FIG. 9 is a polishing substrate. It is a side view which shows the state which provided the adhesive agent at the both ends of a groove | channel. 2 ... Clad part, 3 ... Core, 5 ... Polished optical fiber, 6 ... Groove, 11 ... Optical fiber, 14 ... Optical fiber coupler, 15 ... Grooved substrate, 16 ... Polished substrate, 17 …… Abraded surface, 18 …… Contact part, 19 …… Extended part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Kawakami 1440 Rokuzaki, Sakura City, Chiba Prefecture, Fujikura Cable Co., Ltd.Sakura Plant (72) Inventor Yoshio Kikuchi, 1440, Rosaki, Sakura City, Chiba Fujikura Cable Co., Ltd.Sakura Plant ( 72) Inventor Cho Fukuda 1440 Rokuzaki, Sakura City, Chiba Fujikura Electric Co., Ltd. Sakura Factory (56) References JP-A-60-41007 (JP, A) JP-A-62-180308 (JP, A)

Claims (1)

[Claims] 1. A polished optical fiber in which a clad portion of a part of an optical fiber is removed by polishing to form a polished surface exposing a core vicinity portion, and the polished optical fiber is embedded in a groove, and Two polishing substrates consisting of a grooved substrate for fixing with the polishing surface facing upward are used, and each polishing surface of these polishing substrates is contacted to form a contact portion. In the optical fiber coupler for coupling, the grooved substrate has, at both ends of the groove, an extended portion having a width capable of accommodating the coating of the polishing optical fiber and penetrating from the upper surface to the lower surface of the grooved substrate. An optical fiber coupler in which a coated portion of a polished optical fiber is put in the expanded portion and fixed to a grooved substrate with an adhesive.