JPS63150603A - Connecting device for optical fiber core - Google Patents

Abstract

PURPOSE:To align individual core conductors with high accuracy by driving and controlling a bimorph piezoelectric element according to axis deviation measured by an axis deviation measuring means and minimizing the axis deviation between individual core conductors. CONSTITUTION:An optical fiber core connecting device consists of a V-groove substrate 12 which holds the core conductors 1A of optical fibers, the bimorph piezoelectric element 13, an axis deviation quantity measuring instrument 16, a controller 17, and an amplifier 18 which amplifies the signal from the controller 17. Then the instrument 16 measures the quantity of the axis deviation between the tips of the core conductors A; when the axis deviation is comparatively large the elements 13 provided to both sides of V groove 11 of the substrate 12 are moved finely to perform control and when the axis deviation is not so large, the core conductor 1A on one side is moved finely while the core conductor 1A on the other side is held as it is. When a fine movement adjustment is made, the element 13 on one side of the V-groove 11 where a core conductor 1A to be adjusted is controlled according to information regarding to the axis deviation fed back to a controller 17 so that the axis deviation is minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an optical fiber splicing device, and more particularly to a multi-fiber optical fiber splicing device that is equipped with a glaze aligner for each fiber. It is something.

[Prior Art] As a device for connecting high-density fibers made of a plurality of optical fibers, such as tape fibers, there is a multi-fiber batch fusion type splicing method. Conventionally, in this type of multi-fiber optical fiber splicing device, the axes of the optical fibers are aligned with V? as shown in FIG. It was carried out only by M's guide.

That is, in this figure, 1 is an optical fiber tape held by a clamp member 3 on a fine movement table 2,
The clamp member 3 is provided with a hard clamp 3A and a soft clamp 3B, and the tip of the core wire IA is held by the soft clamp 3B guided onto the V gantry 4. In this way, by pushing the 11 units 2 toward each other in the direction of the arrow, the tips IAs are brought close to each other, and the connections are made by melting. However, if the dimensions and alignment of the left and right grooves are not perfect, all It is not possible to align the optical fiber core IA with high precision. That is, in reality, there is a limit to the high precision of the dimensions and positioning of the V-groove, and glaze misalignment errors are likely to occur in the fiber core 131A. Become.

Optical fibers can generally be divided into two types: multimode graded fibers with a core diameter of 50 μm and single mode fibers with a core diameter of several μm. In the case of multi-core connections of multimode graded fibers, the core diameter is relatively large at 50 μm, a certain degree of IFIll misalignment error is allowed, and even if axis alignment is performed using only the grooves mentioned above, the connection loss can be reduced to O, l.
It is possible to suppress it to below dB.

However, since the core diameter of a single mode fiber is several μm, the splice loss due to glaze misalignment is [very large] compared to a multimode graded fiber, as shown in Figure 8.
For example, if the core diameter is 5 μm and the axis misalignment is 2 μm, the theoretical splice loss for a graded multimode fiber is very small at 0.066 (dB), but for a single mode fiber, the theoretical splice loss is 2 μm. (dB).

Therefore, we set the splice loss of the single mode fiber to 0.1 (d[
1) In order to achieve the following, it is necessary to suppress the amount of glaze misalignment to 0.49 μm or less, and this limitation of glaze misalignment cannot be achieved simply by combining medium + h with only groove guides, but with multiple cores. A glaze alignment mechanism is required that independently aligns the axis of each core fiber of the tape core wire 1 one by one.

FIGS. 9A and 9B respectively show examples of high-precision axis alignment mechanisms that have been used for conventional single-core splicing of single-mode fibers. These include stress strain type and lever type.
Each of these mechanisms has a cantilever 6 as shown in FIG. 9A or a lever 7 as shown in FIG. 9B, and is moved by the slight movement of a micrometer 8 driven by a motor (not shown) to move the fiber core IA. The glaze is matched by slightly moving the V gantry 4 that supports the glaze in two dimensions. Note that 9 is a coil spring for MjL.

[Problems to be Solved by the Invention] However, in the above-mentioned device for single-core connection of single mode fibers, a cantilever or lever, a micrometer, and a motor as its driving source are installed for each fiber core. Two of each must be provided, which increases the size of the structure. In addition, for example, in the case of a 10-core tape fiber, the spacing between the fiber cores is approximately 0.25 m/m, so the above mechanism is incorporated in such a space. That's almost impossible. Moreover, even if it were possible, it would require 20 micrometers, motors, etc., making it expensive.

The present invention focuses on the above-mentioned conventional problems, and in order to solve them, provides a compact multi-core optical fiber splicing device that is capable of independently aligning each fiber core with high accuracy. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a groove substrate which is arranged at positions facing each other and supports individual fibers of a multi-core optical fiber by a plurality of V-grooves. (2) A bimorph piezoelectric element disposed on both side walls of the groove and having a tip protruding toward the opposing V-groove substrate, means for bringing the core wire into close contact with the bimorph piezoelectric element, and core wires facing each other. and means for controlling the bimorph piezoelectric element to change the direction of the tip of the core wire by driving the bimorph piezoelectric element in accordance with the amount of axis misalignment. It is characterized in that the axis misalignment between the core wires of the arranged multi-core optical fibers is adjusted.

[Function] According to the present invention, by providing bimorph piezoelectric elements on both wall surfaces of a plurality of V grooves provided on a substrate, by controlling the applied voltage to be supplied to these bimorph piezoelectric elements, the piezoelectric elements The joint ends of the individual core wires can be independently turned up, down, left and right along the axis, and the amount of axis misalignment can be adjusted to the minimum, reducing the connection loss in all core wires to 0.
It is possible to keep it below 1 dB.

[Examples] Examples of the present invention will be described below in detail and specifically based on the drawings.

1A to 1C and FIG. 2 illustrate one embodiment of the present invention. In the following, the means for fusing both tape cores to be joined and the means for bringing the ends of both tapes close to each other for fusion may be different from conventional optical fiber splicing devices. Since there is no such thing, the drawing and explanation thereof will be omitted.

1A to 1C, the core wires IA of the 11-digit multi-core optical fiber are each held in the vicinity of their tips by V-grooves, and 12 is a V-groove substrate provided with a plurality of V-grooves 11. Reference numeral 13 denotes a bimorph piezoelectric element disposed on the side wall of each groove 11. As is well known, the bimorph piezoelectric element 13 is constructed by joining two piezoelectric plates, and electrodes 14 are disposed on both outer sides thereof. It is being Thus, the free end of the bimorph piezoelectric element 13 provided with the electrode 14 is connected to the V-groove substrate 1 as shown in FIGS. 1B and 1C, respectively.
1 so that the curvature generated in the cells of the bimorph piezoelectric element 13 is transmitted to the core wire IA.

In addition, 15 is a clamp plate, and the individual core wires IA are
By setting the clamp plate 15 in the groove 11 of the groove substrate 12 and pressing the clamp plate 15, each of the core wires IA is bent, and its restoring force causes the tip of the core wire to be crimped to the bimorph piezoelectric element 13. can be kept.

Now, the tips of the core wires IA fixed by the clamp plate 15 in this way are brought closer to each other from the state shown in FIG. 1B to be in a position close to performing fusion, and then the amount of axis deviation is determined as shown in FIG. 2. The measuring device 16 measures the amount of axis misalignment between the tips of both core wires IA, and if the amount of glaze misalignment is not so large, the core wire IA on one side is kept as it is, and the core wire IA on the other side is Follow the steps below to make slight movements.

Note that here, as the axis deviation measuring device 16, ITV
Although it is possible to minimize the axis misalignment by setting the maximum value of the power passing through the combination of the television and the image processing system or the core of the optical fiber core IA to be connected, usually T
The amount of axis deviation is determined by monitoring the images of light transmitted through the optical fiber from two opposing directions using a V camera and processing the images.

Therefore, once the amount of axis deviation has been determined as described above, first select the bimorph piezoelectric element 1 on either side of the V-groove 11 holding the core wire IA on the side where the imaging adjustment is to be performed.
3, so that the axis misalignment becomes the minimum value. That is, the amount of imaging at this time is determined by the PID according to the signal by constantly feeding back information regarding the amount of axis deviation described above from the axis deviation measurement device 16 to the controller 17.
This is carried out based on a control law, and by repeating this operation several times, it is possible to minimize the amount of glaze shift. In addition, in FIG. 2, 18 is the controller 1.
This is an amplifier that amplifies the signal from 7.

In addition, if the initial axis misalignment amount is relatively large, V m
It is necessary to perform control by slightly moving both bimorph piezoelectric elements 13 provided on both sides of the PVDF bimorph piezoelectric element 11, and an embodiment in which the force and displacement amount necessary for actual alignment can be generated using the PVDF bimorph piezoelectric element. will be explained below.

Figure 3 shows a bimorph piezoelectric element 1 formed at VtR11.
3 is taken out and shown, and its dimensions are as follows: the length λ protruding from the edge of the substrate 12 is I n+m, the thickness h of each piezoelectric plate is 0.02 mm, and the width is 0.1 m.
m, so that it can be adapted to the actual V-groove 11. Now, the applied voltage V-50 (V
) Then, the amount of displacement and the force generated at the tip of the element 13 have the following values.

-18 (μm) ... (1)
Force F −Ebhds+V I1 4×1 = 57mgf...
(2) Here d3. : piezoelectric constant, E: longitudinal elastic constant.

However, the displacement amounts and forces shown in equations (1) and (2) are for a state where the optical fiber is not set. Therefore, when the optical fiber is set, the amount of displacement of the piezoelectric element is reduced by the repulsive force from the optical fiber. Therefore, next we will calculate the amount of displacement in such a case.

FIG. 4A shows a state in which the optical fiber core j, 21A is set in the V-groove substrate 12. IB is the optical fiber coating. At this time, the optical fiber core Is I A has an initial deflection a
is given, and since it is clamped by a clamp plate (not shown), the restoring force of the core wire IA is applied to the piezoelectric element 1.
It acts on 3. The force at this time is F as shown in Figure 4B.
Let a be that V? Let Fn be the vertical component force acting on the element 13 on the R side.

FIG. 5A schematically shows such a set state. When a voltage is applied to the bimorph piezoelectric element 13 in this set state, the fiber core IA is pushed up due to deformation as shown in FIG. 5B, for example. The curved state is balanced when the reaction force R due to the elasticity of the fiber core IA itself and the force generated in the element 13 are balanced.

Therefore, if the amount of displacement at this time is yl, the reaction force Fa due to the initial deflection a is expressed by the following equation.

Fa=-3Erlfa/ 11 y3"" (3) Here, Ef: Longitudinal elastic constant of the optical fiber If: Second moment of area of the optical fiber fly: Length of the optical fiber Therefore, normal direction component force Fn of the piezoelectric element 13 When the inclination θ of the piezoelectric element 13 is 45°, Fn−-315x E(Iya/ 11 t”
・= (4) Also, the force Fr that presses the optical fiber core IA against the piezoelectric element 13 at the equilibrium point is Ef -3EtIrym/-'2 r3
...(5) Therefore, at the equilibrium point, the piezoelectric element 13
The reaction force R that the tip receives is 11=Fn"Fr"-(33'm"3/ffa) E
II(/j213...(6).

Also, the displacement fi at the distance x from the fixed end of the piezoelectric element 13
y is the reaction force exerted on the tip of the piezoelectric element 13, and when the moment generated by the applied voltage R1 is Mv, it can be expressed as shown in the following equation.

Here, j2: length X of the piezoelectric bimorph element/distance from the fixed end Therefore, the displacement fiyn can be expressed as in the following equation by substituting equation (6) into equation (7).

Therefore, d, +-4X 10-' (mm/V),
V-50 (V) b-0,1 (mm), h-0,02 (
mm), d-0,125 (mm).

E-1,9x to' (3/mm2).

5-7Jx 1106(/mm'), x-1(mm
).

Yu f-10 (mm) In this case, the relationship between a and yl is as shown in FIG.

That is, as shown in this figure, by controlling the initial deflection amount a of the optical fiber, the axial displacement II V m can be controlled, and the axial displacement amount 1 (
.mu.m) can be achieved by setting the initial displacement amount of the optical fiber to 0.20 (ff1m) or less in the case of this embodiment.

In the above description, the axis alignment mechanism in a multi-core optical fiber splicing device has been described, but it goes without saying that the present invention can also be applied to a splicing device for single mode optical fibers.

[Effects of the Invention] As described above, according to the present invention, there are provided V-groove substrates that are arranged to face each other and support individual core fibers of a multi-core optical fiber by a plurality of V-grooves; A bimorph piezoelectric element is provided on both side walls of each V-groove and has a tip portion projected toward the opposing groove substrate side, and the individual core wires are brought into close contact with the bimorph piezoelectric element, By driving and controlling the bimorph piezoelectric element in response to the axis misalignment measured by the total axis misalignment measuring means, the axis misalignment between individual fibers is minimized, making it possible to create multicore optical fibers, which was previously difficult. It has become possible to achieve high-precision axis alignment of individual core wires.

[Brief explanation of the drawing]

FIG. 1A is a schematic diagram showing the arrangement of the V-groove substrate and the bimorph piezoelectric element provided in the V-groove according to the present invention in a state where optical fiber cores are set, FIG. 1B is a side view of that state, and FIG. 1C is a top view of the state, FIG. 2 is a configuration diagram of the axis alignment mechanism according to the present invention, FIG. 3 is a perspective view schematically showing a bimorph piezoelectric element applied to the present invention, and FIGS. 4A and 4B are A state diagram in which an optical fiber is set on a substrate according to the present invention and a vector diagram for explaining that a repulsive force is generated due to initial deflection in that state, FIGS. 5A and 5B, are as shown in FIG. 4A. Figure 6 is a reference diagram for theoretically calculating the amount of displacement that occurs when a bimorph piezoelectric element is driven under the following conditions. Figure 7 is a schematic diagram showing an overview of the configuration of a conventional multi-core optical fiber connection device; Figure 8 is a graph showing an example of the relationship between single-mode optical fiber and graded multi-mode optical fiber. Figures 9A and 9B are perspective views respectively showing two aspects of the axis alignment mechanism in a conventional single mode fiber splicing device. IA... Optical fiber core wire, 11... V groove, 12... V groove substrate, 13... Bimorph piezoelectric element, 14... Electrode, 15... Axial deviation measuring device, 16. ...controller, 17...amplifier.

Claims (1)

[Scope of Claims] 1) V-groove substrates that are arranged in opposing positions and support individual fibers of a multi-core optical fiber through a plurality of V-grooves; and a bimorph piezoelectric element having a tip protruding toward the V-groove substrate; a means for bringing the core wire into close contact with the bimorph piezoelectric element; and a means for measuring an amount of axis misalignment between the core wires facing each other. and means for controlling the bimorph piezoelectric element so as to drive the bimorph piezoelectric element in accordance with the amount of axis deviation to change the direction of the tip of the core wire, the control means controlling the bimorph piezoelectric element disposed at the opposing position. An optical fiber splicing device characterized by adjusting the axis misalignment between the cores of multi-core optical fibers. 2) In the optical fiber connecting device according to claim 1, a deflection is generated in the core wire by means of bringing the core wire into close contact with the bimorph piezoelectric element, and the amount of the deflection is determined by the amount of the deflection. An optical fiber splicing device characterized in that the change is made by driving the optical fiber.