JPH043003A - fiber optic coupler - Google Patents

Abstract

PURPOSE:To easily and inexpensively form the optical fiber coupler by providing a coupler body with a groove which is previously curved with a predetermined certain curvature and a branch optical fiber and embedding the optical fiber in the groove thereof. CONSTITUTION:The curved groove 5 of a lower half part and a straight groove 6 are formed atop the optical coupler body 4 in the same size as the outside diameter of the optical fiber body from which the covering is removed. The optical fiber body 7a the tapered surface 7b of which is formed at a predetermined angle and the covering of the branch optical fiber 7 of which is removed is mounted in the straight groove 6 and the exposed optical fiber 10a is so curved and fitted from above as to be positioned along the curved groove 5. These optical fibers are then adhered by an adhesive 11. Upper caps 8, 9 are adhered and fixed simultaneously therewith to complete the optical fiber coupler 20. The optical fiber coupler is easily and inexpensively obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical fiber coupler used in optical communications, optical CATV networks, and optical fiber computer network lines.

[Conventional technology J: An optical coupler is required to add a signal to an optical fiber transmission line midway or to branch and take out a signal, but with conventional methods, it is necessary to cut the optical fiber and connect it. . For example, as shown in FIG.
When transmitting the signal from optical fiber 2 to It is configured like this.

However, such a connection causes excessive transmission loss, and when couplers are connected vertically in multiple stages, there are problems such as a limit to the number of stages.

[Problems to be Solved by the Invention] Covering as many terminals as possible with as many optical fibers as possible is important from the viewpoint of utilization efficiency and economy. That is, the cost per terminal is related to the total cost/number of terminals, and it is necessary to increase the number of terminals as much as possible. For this purpose, a low-loss coupler is absolutely necessary, and in order to achieve low loss, it is necessary to input and output optical signals without cutting the optical fiber. For this reason, it is known that it is sufficient to curve the optical fiber and bring the tip of another branch optical fiber into contact with this curved portion.

At this time, it is important to maintain an optimal contact angle with the branch optical fiber.6However, it is difficult to obtain this optimal angle and to stably fix the optical fiber simply by freely bending the optical fiber. It is. -1 The optimal contact angle is
As shown in the example, since the angle is extremely small at 8 to 10 degrees, it is considered technically difficult to precisely process the tip of an optical fiber with such a sharp angle, and its application as an optical fiber coupler is being considered. It had not been done.

The present invention has been made in view of these points, and an object of the present invention is to provide a novel non-destructive coupler.

[Means for Solving the Problems] The present invention provides a method for branching or combining optical signals by bringing the tip of an optical fiber, which is another branch, into contact with a curved portion of a curved optical fiber at a certain angle. In a fiber coupler, the coupler body has a pre-curved groove with a certain curvature and a branch optical fiber, and by burying the optical fiber in the groove, it is possible to easily branch and combine optical fiber signals. This optical fiber coupler is characterized by being able to satisfy the following conditions.

Further, the present invention is an optical fiber coupler having a structure in which an optical fiber is pressed by a member having sides with a predetermined curvature in order to achieve the function of branching and coupling optical fiber signals.

[Embodiment] Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 to 9. FIG. 1 is a perspective view of the bottom portion of the optical fiber coupler of the present invention. That is, the optical coupler main body 4 is a rectangular plate-like member, and is made by extruding plastic or fine ceramics using a precision mold, or by forming grooves on a glass substrate by etching or the like.

A lower half curved groove 5 and a straight groove 6 are formed on the upper surface of the optical coupler body 4 and have the same size as the outer diameter of the optical fiber body from which the coating is removed. The cross-sectional shape of these 5 and 6 parts is round, square, V-shaped, or stepped, so that the optical fiber can be stably fixed.

The straight groove 6 is for placing the optical fiber main body 7a from which the coating of the branch optical fiber 7 has been removed, as shown in FIG. 2, and the tip of the branch optical fiber main body 7a is
As shown in the enlarged front and side views of A) and (B), the tapered surface 7b is created by precisely cutting the tapered surface 7b at a predetermined angle using a high-speed rotating diamond cutter blade saw or the like. The angle of this taper must be selected to an optimum value depending on the wavelength; for example, in the case of a multimode optical fiber, the angle is 8 to 10'' for light with wavelength λ=o and aa of 3 μm.

The tapered surface 7b is installed so as to be parallel to the wall of the curved groove 5, as shown in the top view of FIG. Then, a top cover 8 having a groove in the upper half of the branch optical fiber 7a on the bottom surface is placed from above, and the branch optical fiber 7a is embedded and fixed with adhesive.

Next, as shown in FIG. 6, the coating of the optical fiber 10 having a width corresponding to the optical fiber coupler body 4 is peeled off to expose the optical fiber body 10a. and,
FIG. 7 shows a state in which the exposed optical fiber 10a is curved and fitted from above along the curved groove 5.

Subsequently, the adhesive 11 is dropped using a dropper 12 or the like, and the tapered surface 7b of the branch optical fiber 7 and the optical fiber 10a are bonded together, and the upper cover 9 on the curved portion side is fixed with adhesive, thereby completing the optical fiber coupler 20 of the present invention. do.

Next, a second embodiment will be described based on FIG. 1O and FIG. 11. In this example, there is no groove in the coupler body, and the elasticity of the holding member and the cushion member is used to bring the optical fiber and the branch optical fiber into contact. That is,
The coupler body 21 has a branch optical fiber 7 attached to the left protrusion 21a.
Hole 2 into which the optical fiber body 7a from which the coating has been removed is inserted.
2 is bored, and the branch optical fiber 7 is inserted and fixed so that its tip tapered surface 7a is flush with the stepped portion 21b. In addition, cushioning materials 23 made of a slightly soft material such as soft rubber or sponge rubber are pasted and fixed on both sides of the stepped portion 21b.

Subsequently, as shown in FIG. 6, the optical fiber 10 with the coating removed by the width of the coupler body 21 of the optical fiber 10 is
As shown in FIG. 1, the curved portion 25a is curved while abutting against the cushion members 23 on both sides to form a curved portion 25a having the same thickness as the step portion 21a of the coupler body 21 and a curvature that gives a predetermined curvature to the optical fiber 24. The cover body 25, which has a groove 25b into which the optical fiber body LOa is inserted, is pressed to the left in the direction of the arrow so as to sandwich the optical fiber 24, thereby forming a curve in the optical fiber 24 and fixing it with adhesive. . The optical fiber 24 is bent and comes into contact with the tapered surface 7a at the end of the branch optical fiber 7 to form an optical fiber coupler 30.

Next, a third embodiment of the invention will be described. In this example,
When installing the optical fiber 10, if the coating of the optical fiber 10 is peeled off and exposed to air, there is a risk that the transmission loss of the optical fiber 10 will decrease and the strength will decrease. The optical fiber coupler is formed by attaching the fibers with the fibers covered as much as possible, and then quickly bringing only the contact surfaces into partial contact.

In FIG. 12, a coupler body 31 has a branch optical fiber 7 fixed to a protrusion 31a without forming a groove, like the coupler body 21 shown in FIG. is fixed. Subsequently, as shown in FIG. 13, the coated optical fiber 10 is bent and placed so as to be pressed against the stepped portion 31b. A cross-sectional view of this state is shown in FIG.

Next, as shown in FIG.
A cut 34 is made in the coating at this portion. FIG. 15 shows a cross-sectional view of this coating with a cut 34 made therein.

Next, the lid 32 having the optimum curvature R at the tip is pressed in the direction of the arrow from the opposite side of the cut 34, as shown in FIG. The coating at the cut end 34 is expanded to expose the optical fiber main body 10a, and the branch optical fiber 7 at the stepped portion 31b is expanded.
The fiber body 10 of the optical fiber 10 is attached to the tapered surface 7b of the optical fiber 10.
Contact a. A sectional view of this state is shown in FIG. 17. In this state, the upper cover 32 is fixed with adhesive. If necessary, this is further sealed to form the optical coupler 40.

Therefore, in this example, since the optical fiber can be brought into contact immediately without removing its coating, an optical fiber coupler can be formed without any loss in the strength of the optical fiber or without causing transmission loss. be able to.

The dimensions of these couplers are 5 mm in height and 15 mm in length.
mm and width is about 15 mm.

[Effects of the Invention] As described above, according to the present invention, a coupler that adds a signal or takes out a signal from the middle of an optical fiber can be easily connected without cutting the optical fiber. Moreover, the structure is simple and can be formed at low cost. This results in a non-destructive coupler that can minimize optical fiber strength and transmission loss.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the bottom part of an optical fiber coupler according to an embodiment of the present invention, FIG. 2 is a perspective view showing a state in which a branch optical fiber is placed on the top surface of the optical coupler main body, and FIG. FIG. 4 (A) and (B) are a side view and a front view of the branch optical fiber, and FIG. 5 is a perspective view showing the state in which the lid is placed on the optical coupler. Figure 6 is a front view of the optical fiber with the coating removed, Figure 7 is a top view of the optical fiber inserted into the optical coupler body, and Figure 8 is the adhesive. FIG. 9 is a perspective view showing the completed state of the optical coupler; FIG. 10 is a perspective view of the optical coupler main body of the second embodiment of the present invention; FIG. 11 is the optical fiber 12 is a perspective view showing a state in which a branch optical fiber is attached to the optical coupler main body of the third embodiment of the present invention, and FIG. 13 is an optical coupler with a branch optical fiber attached. Figure 14 is a top view showing the state in which the optical fiber is placed, Figure 14 is a top view showing the state in which the optical fiber is cut, and Figure 15 is the state in which the cut optical fiber is pressed and connected. Top view, Figure 16 is a sectional view of Figure 13, Figure 17 is a sectional view of Figure 14, Figure 18 is a sectional view of Figure 15, Figures 19, 20 and 21. 1 is a schematic configuration diagram for explaining a conventional optical fiber branch connection. 4.21.31... Optical coupler body 5.6... Groove 7... Branch optical fiber 8.9, 25.32... Lid body 10... Optical fiber

Claims (2)

[Claims] (1) In an optical fiber coupler that branches or combines optical signals by bringing the tip of another branch optical fiber into contact with the curved part of the curved optical fiber at a certain angle, the coupler body has a pre-defined curvature. An optical fiber coupler characterized in that it has a curved groove and a branch optical fiber, and by burying the optical fiber in the groove, it is possible to easily branch and combine optical fiber signals. (2) An optical fiber coupler having a structure in which an optical fiber is pressed by a member having sides with a predetermined curvature in order to achieve the function of branching and coupling optical fiber signals.