JPS6029712A - Setting method of optical fiber end surface interval of welding connection method of optical fiber - Google Patents

Abstract

PURPOSE:To make a high-strength welding connection which has small light loss by allowing an optical signal to travel in optical fibers whose end parts face each other, and moving and placing the optical fibers in a zero end surface interval state and a specific interval state. CONSTITUTION:Optical fiber end parts 7A and 7B are moved as shown by arrows through slip holders 3A and 3B to approach each other, an optical signal from a transmitter 9 is detected by a receiver 10, and the photodetection level drops when both ends 8A and 8B abut on each other, so the movement is stopped. Then, one optical fiber is moved back by a specific extent to hold an initial end surface interval L2, and discharge is caused between discharge electrodes 4M and 4N to weld the fiber end parts together. The optical signal is therefore detected while the end surface interval is zero, so there is no flection due to the contacting, and the end surface interval L2 is held accurately, so that the high-strength welding connection having small light loss is made.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for setting the spacing between optical fiber end faces in an optical fiber fusion splicing method.

The fusion splicing method, which has been adopted as a permanent splicing method for optical fibers, is said to have advantages such as low splicing loss and high tensile strength at the optical fiber joint.

Among the conventionally adopted fusion splicing methods mentioned above, the technically advanced one is shown in Figure 7151 (a). Holder f31A, +31B, a pair of discharge electrodes +41M,
F4) A device equipped with N, etc. is used, and two recesses t117 (1) a and fil b of V Il- arranged in a straight line are formed on the top surface of the lTl+ combination stand (1). Along with each slip holder +31A
, 131 There are cherry bark pins a1 to a4 on the top surface of B, respectively.
, b1 to b4 are erected.

On the other hand, a pair of optical fibers t51 A and 15113 have coated portions +6) A and (6) B, but their ends [71 A].

(7) B has the coating removed, and the coating part (G) A,
(6) The lengths from B to the end faces f81A and +81B, that is, the lengths of the ends (force A and +71B) are uniform.

” When fusion splicing a pair of optical fibers (0)A and (5)B, the covering part t6 is first
1 A, (6) B is slip holder +31 A
, +31 B each contact pin a1 to a4, b1 to 1) 4
Insert the optical fiber ends (7) A, (
7) B is the 6-concave n17 (+) a of the shaft mounting base (1),
(I) Fitted into b.

Next, the slip holder (3) is attached via a drive system (not shown).
A, (3) B are moved in the direction of the arrow in Fig. 1 (a), and as a result, the optical fiber ends (7) ＼, (7) The end faces t8) A and +81 B abut against the end face spacing setting plate (2), resulting in the state shown in FIG. 1(b).

At this point, the slip holder (31A, +3113) is stopped immediately, but due to the above-mentioned excessive feeding, each end face t
Even if 81A and +81B are strongly pressed against the end face spacing setting plate (2), each cherry bark pin a1 to a4 and b
Phase L of 1 to b4 and each covering part (61A, +61B
Since slip occurs in L, the optical fiber end face t8] A
.

(8) No abutting force that would damage B acts on it.

After that, the end face spacing setting plate (2) is adjusted to each end face (8)A, (8)
) B was removed from work, and the optical fiber (51A) was removed from work.

(5) Both or one of B, for example, the original fiber (5) A, is moved so that the end face [8] A , +8)
B is set at a predetermined interval, and at this time, the interval between the end faces [8] A and +81 B is determined by 6゛4 using a microscope or the like, and if this is appropriate, the process proceeds to the next step.

Furthermore, apart from the case of a multimode optical fiber, in the case of a single mode optical fiber, more precise alignment is performed at this lR+ point.

After the end face spacing setting plate (2) is removed, either one of the optical fiber ends (7)A, (7)B is moved toward the other, and each end face (8)A, (8)B The interval is shown in Figure 1 (
When it is narrowed to the state of c), a pair of discharge electrodes (4
)M, (4)N discharge starts, and the following is shown in the same figure)
As shown in (E), the optical fiber ends i71A, (71B) are fused and spliced through end-butting movement and discharge heating, and after the connection, the discharge stops as shown in (F) of the same figure.

Here, the end face spacing (Fig. 1 (
The state (b)) is referred to as the phase interval L1, and the end face interval suitable for the subsequent start of discharge is referred to as the initial end face interval L2.

Normally, the end face spacing setting plate (2) is set to have an o5 thickness in view of its mechanical strength, processing accuracy, etc., and therefore the phase spacing L1 is 0.511111.

On the other hand, the initial end face spacing L2 is the optical fiber end moving speed (butting speed) after the spacing is set to 50 μm/sec.
Generally speaking, it is said that about 2 cents is good.

In other words, if you set L2 to 20 μm or more and start discharging, the end of the optical fiber will be exposed too much, and conversely, L2 will be set to 20 μm or more.
pm or less, insufficient melting of the optical fiber end will occur, and in any case, the problem of splice loss is undesirable because the fusion strength of the spliced portion will decrease.By the way, the phase spacing L1 in the above % Since the moving speeds of the optical fiber ends are all known -11 terms, it can be said that the initial end face spacing L2 can be easily set by moving the optical fiber ends by a predetermined amount after setting the phase spacing L2. However, in reality, L2 cannot be set accurately, causing the above-mentioned problem.

In other words, when setting the phase spacing L1, the optical fiber end face +8
) A , , +81 B is firmly pressed against the end face spacing setting plate (2) in order to achieve the 11'6 abutting state, but in such a case, the slip holder +31
Even though A and +31B are used, each optical fiber end t7) A and +71B is bent, and the spacing setting plate (
2) After leaving work, the fiber ends of each party (71A) were bent.
.

(7) When B is restored to a straight shape, an error occurs in the phase interval L1 by the amount of deflection.

Of course, after setting the phase spacing, L1 is inspected by microscopic observation, but this also involves an error of about 1 .mu.m, so high reliability cannot be obtained.

Therefore, when setting the initial end face spacing L2 based on the rough spacing L1, considerable variation will occur.

In order to solve the above problems, the present invention improves the accuracy of the end face spacing in the optical fiber fusion splicing method.
The specific method will be explained below using illustrated examples.

In FIG. 2 (a) illustrating the method of the present invention, the shafting table (
11, y, 'J 77'' Horta (31A-(311
3. Release? ! The electrodes +41M, +4)N, etc. are the same as in the case of Fig. 1 (A) above, and the optical fiber (51A
, (51B is the covering part ((31A).

(6) B is each slip holder +31 A, (3+
13 cherry bark bottles al a4, b, ~l) * between navel J
T is inserted into each, optical fiber end (7) A, +718
is the prestigious FEN [+1 a,
tll b, respectively.

In the case of the present invention, one optical fiber (51A has L
An optical transmission device (9) equipped with an ED etc. is optically connected, and an optical receiving and detecting device aω equipped with an APD etc. is optically connected to the other optical fiber. When the optical fiber ends [71A, +71B are moved in a pulsed manner in the direction of the arrow in FIG. fiber(
An optical signal is constantly transmitted across 51B, and the level of the received light is detected by an optical reception and detection device (GO).

When the optical fiber end portions t71A, 17113 are moved in this way and their end faces f81A, (81B) are brought closer to each other, as the distance between the end faces narrows, the light reception level increases as shown in Fig. 3, but as shown in Fig. 2( When the end faces +81A and +81B touch each other as shown in b), the light receiving level suddenly fluctuates as shown in T in FIG. 3.

Therefore, when the light reception level is monitored through the light receiving and detecting device aω, the state shown in FIG. 2 (B) can be detected due to the occurrence of T in FIG. If the movement of 31B, that is, the end of the optical fiber (force A, t71B) is stopped, the end face of the optical fiber (81A) is stopped.

18) The distance between the end faces of B becomes 0, and the optical fiber end t7]
A will not be deflected by the force B.

After the state shown in FIG. 2 (→) is achieved as described above, either one of the optical fiber ends t71 A and +7113 is moved by a predetermined amount in the direction of the arrow as shown in FIG. The interval V5L2 is set.

Below, a pair of emitting electrodes +41M and 41N start discharging, and as shown in Fig. 2) (e), the optical fiber end 171A is moved through the end butt movement and discharge heating.
, (7) B is fused and spliced, and after the connection, the discharge stops as shown in (f) of the same figure.

In addition, in the above, the end face spacing setting plate (
2) Optical fiber end +81A, 18 without using
1B is butted as shown in Figure 2 (B), but between the culms in Figure 2 (A) and the same figure (B), the mill spacing by the above-mentioned spacing setting plate (2), A setting step may be included. In this case, it is sufficient to pass optical signals through the optical fibers +51A and 151B from the time of setting the i11 interval. Also, the optical fiber ends (7)A and (7)B may be moved relative to each other at each point. When making these ends +71 A, +71
'13 may be moved, or both may be moved.

Furthermore, the drive system for the slip holders 31A and 31B used to move the optical fiber ends is preferably equipped with a motor capable of continuous drive and pulse drive, and the power of this motor is transferred to the cam feed 9. The information is transmitted to a mechanism etc. and the cam mechanism causes the slip holder t31A,
+31 When moving B in a predetermined direction, the coarse interval L1
When setting, the motor is driven continuously, and when setting the initial end face distance L2, the motor is driven by pulses (the feed amount of one pulse is 1).
It is preferable to make the distance (about 100 μm).

As a heating means for fusion splicing the optical fiber ends (7)A, (7)B, in addition to the above-mentioned discharge heating, laser heating can also be used.On the other hand, the optical fiber ends (7)A, ( 7) If each process from setting B to completing the fusion splicing of these end portions t71A and 71B is to be automated, each process will be electrically, electronically, and It can be controlled mechanically, and in particular in this case, the change in the received light level (T in Figure 3) when the optical fiber end faces t81A and +81B are butted together is detected by the optical receiving and detecting device (10+) and from there the change is detected by the computer. By sending a predetermined output signal to the arithmetic circuit or the like, the steps shown in Fig. 2(e), (e), and (f) can be automatically performed, including stopping the slip holder at the time when the end faces are brought together.

Furthermore, the above-mentioned initial surface spacing L2 is the original fiber end (7
) The outer diameter of A, (7) B, the insertion of the glass composition forming the 41'4 diameter, the moving speed of the optical fiber end almost synchronously with the start of heating, and the amount of light of 774,741 parts. Addition,
! I' + i + may be other than the 20 μm mentioned above depending on the IVi crystal, specifically, L2 is 5 μm bloμI
There are also blades such as ns 15μ+n% 2sμm.

As explained above, the present invention makes the ends of a pair of optical fibers face each other and sets the distance between the end faces of the two optical fibers, and then irradiates the ends of these optical fibers with 116 degrees of thermal energy. In the method of fusion splicing optical fibers of 1 thread J by abutting the end faces of both optical fibers against each other from (C), the above-mentioned pair of optical fibers whose ends are facing each other is An optical signal is passed through the fibers, and the end portions of both fibers are moved relative to each other in the direction of abutment to abut each other, and the abutment state is detected by a change in the received light level of the optical signal, and the ends of the optical fibers are abutted. The movement is stopped, and then the end portions of both optical fibers are relatively moved by a predetermined amount in the direction opposite to the abutting direction to set the distance between the end faces of both optical fibers.

Therefore, in the case of the present invention, the end face abutting state (distance between end faces 12j4 = 0), which is a reference when setting the end face interval, is reliably determined by detecting the received light level, and at the same time, the butting movement of the optical fiber end is stopped. There is no bending that would cause errors at the ends of the optical fibers, and as a result, by moving the ends of the optical fibers in the opposite direction to the butting direction with the end face spacing = 0 as a reference, the end face spacing can be set accurately. In addition, because the end face spacing is exactly 4', it is possible to realize optical fiber fusion splicing with low loss and high strength.

[Brief explanation of the drawing]

Figures 1 (a) to (f) are explanatory diagrams of the conventional method, and Figure 2 (a)
~(f) is an explanatory diagram showing one embodiment of the method of the present invention, Part 3
The figure is a diagram showing changes in the light reception level when the ends of the optical fibers are brought together. (1)・・・Axis mounting base (Ila, m b”・V-shaped recess rflff+31
A, +31B...Slip boulder (41M, f
・IIN・・・Discharge electrode (51A, +51B...
...Optical fiber (6) A, [G) B...Coating part t71 A, +71 B... End of optical fiber +81 A, +8) I3... Optical fiber End face (9)... Optical transmitter al... Optical reception and detection device L2... Initial end face spacing

Claims (1)

[Claims] After arranging the ends of a pair of optical fibers to face each other and setting the distance between the end faces of the two fibers, the ends of the optical fibers are irradiated with thermal energy and the ends are moved relative to each other in the direction of abutment, This allows both optical fiber end faces to be JL
In a method of fusion splicing a pair of optical fibers by butting them together, the ends are opposite to each other.
Pass the optical signal across the optical fiber of ``...'',
The ends of these optical fibers are moved relative to each other in the direction of the notch, and the end faces of these end faces are brought into contact with each other, and the abutment state is changed to the above-mentioned optical point. ';'''j is detected by the change in the received light level, and the butting movement of the ends of the optical fiber is stopped 1Z, and then both ends are moved relative to each other by a predetermined amount in the opposite direction of the butting direction. A method for setting the spacing between the end faces of original fibers in the optical fiber fusion splicing method.