JPH0990160A - Method and device for connecting optical waveguide and optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always hold the intervals of connection faces to be constant, to detect pressure on the connection faces and to save a Z-axis for a desired distance by stopping movement when the contact pressure of an optical waveguide and an optical fiber is detected. SOLUTION: Output fiber parts 7 are set and light is made incident on the fibers of input fiber parts 5. After light is made incident on the fibers, the Z-axis 8 is automatically moved to the direction of the waveguide parts 4. When the end face of the fiber parts 5 touches the end face of the optical waveguide parts 4, a pressure sensor 9 detects it and an interval (ΔT) controller saves the Z-axis 8 for the prescribed distance. The intervals (ΔT) can be thus controlled. The input fiber parts 5 can automatically be aligned to X and Y-axes so that light which is made incident on the input fiber parts 5 passes through the optical waveguide 4 after contact faces are set at the prescribed intervals (ΔT). Thus, the optimum intervals for reducing a connection loss can be set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting an optical waveguide and an optical fiber, and a connecting device for implementing the method.

[0002]

2. Description of the Related Art Recently, research has been actively conducted to form various optical waveguide components by forming an optical waveguide composed of a core and a clad formed on a flat substrate, and has been actively used in optical communication and optical networks. It is about to be applied.

When such an optical waveguide component is used in an actual system, an optical fiber must be connected for inputting / outputting an optical signal.

The connection method and the conditions required for the device are summarized below.

1) Low connection loss 2) Good reproducibility 3) Short connection time 1) is a basic condition required for connection technology, 2),
3) is an important condition for mass production technology and cost reduction of optical parts.

FIG. 4 shows a schematic structure of a device conventionally used as a connecting device for connecting an optical waveguide and an optical fiber.

In the figure, reference numeral 1 is an optical waveguide component fixing portion,
2 is an input alignment stage, 3 is an output alignment stage, 4
Is an optical waveguide component, 5 is an input fiber component, 6 is a GI fiber component, and 7 is an output fiber component.

In the above-mentioned conventional connection, as shown in FIG. 4, a fine movement stage 2 for centering is provided with a stand for fixing optical fiber parts interposed therebetween.
This is performed by a device in which two sets of 3 and 3 are arranged. Each stage is X,
Performs translational movement in the Y and Z directions and rotational movement about the Z axis.

In order to connect the optical waveguide component 4 and the multi-core fiber component with such an apparatus, the optical waveguide component 4 is fixed to the optical waveguide component fixing portion 1 and the input fiber component 5 is attached to one stage 2 and the other. First, the GI fiber component 6 having a large core diameter is set on the stage 3, and the Z axis of the stage is moved to bring the connecting surface of the input fiber component 5 close to the connecting surface of the optical waveguide component 4. Next, light is incident on the input fiber component 5, and the input fiber component 5 is aligned in the X and Y directions so that the incident light passes through the core of the optical waveguide component 4. Output light that has passed through the optical waveguide component 4 is received by the GI fiber component 6, and the input fiber component 5 is designed to maximize the amount of received light.
Align. Usually, this alignment is performed automatically. After that, the GI fiber component 6 is replaced with the output fiber component 7, and the optical waveguide component 4 and the output fiber component 7 are aligned in the same manner. After the alignment is completed, an adhesive is dropped on the connecting portion to connect and fix the respective parts.

In the conventional connection method described above, the alignment accuracy must be on the order of submicron in order to realize a connection with low loss. Theoretically, a connection loss of 0.1 dB occurs with a positional deviation of 0.75 μm in the X or Y direction. Conventionally, the X and Y axis accuracy of the alignment stage is 0.
A 1 μm stage is often used. As a result, high accuracy is achieved in the alignment positioning in the X and Y directions.

[0011]

However, the conventional Z axis is merely a moving axis for bringing the connecting surface of the input fiber component or the output fiber component close to the connecting surface of the optical waveguide component, and has the function of aligning light. As I am not involved in anything,
The axis movement was done manually. For this purpose, the U
When V adhesive is dropped and both components are connected and fixed, there is a problem that the connection surface interval is not always constant and the connection loss varies depending on the variation in the connection interval.

In the initial state in which the core optical axes of the input fiber component and the optical waveguide component are aligned, if no light is received by the GI fiber, the input fiber component is moved in the X and Y directions at a pitch of, for example, 5 μm until it is received. It is operated to move continuously, but at this time, the connecting surface is 90 ° with respect to the core optical axis.
In parts other than the above, the connection surface may come into contact with each other, which causes a problem that the connection surface is scratched or, in the worst case, the connection surface is damaged.

Therefore, the present invention has been made to solve the above-mentioned problems, and it is possible to always keep the distance between the connecting surfaces constant, and at the same time as detecting the pressure on the connecting surface, retract the Z axis by a desired distance. An object of the present invention is to provide a connection method and a connection device between an optical waveguide and an optical fiber that can be connected.

[0014]

In order to solve the above problems, in the method of connecting an optical waveguide and an optical fiber according to the present invention, the optical waveguide and the core of the optical fiber are arranged so that their optical axes coincide with each other. In the first step, the optical waveguide and the optical fiber are moved closer to each other by moving in the direction along the optical axis, while the contact pressure between the optical waveguide and the optical fiber is measured. It has at least a second step of stopping the movement when detected, and a third step of moving the optical waveguide and the optical fiber by a predetermined amount in a direction opposite to the direction of the movement in the second step. It is characterized by

Further, in order to solve the above-mentioned problems, a connecting device for an optical waveguide and an optical fiber according to the present invention adjusts the optical waveguide and the optical fiber while measuring the transmitted light of the optical waveguide and the optical fiber. In a connecting device of an optical waveguide and an optical fiber for core connection, a means for arranging the optical waveguide and the core of the optical fiber so that their optical axes coincide with each other, and the optical waveguide and the optical fiber described above. It is characterized in that it has means for moving them in the direction along the optical axis to move them closer to or away from each other, and means for measuring the contact pressure between the optical waveguide and the optical fiber in the process of the movement. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A connection device for an optical waveguide and an optical fiber according to the present invention is provided with a pressure sensor on the Z axis of a stage for aligning an input fiber component and an output fiber component,
The connection device is characterized by having a function of detecting a contact state from a non-contact state of the connection surface with this pressure sensor, and setting a detection position to a zero distance to open a desired distance.

According to the connection device of the present invention, since the connection surface distance can be always kept constant, not only the connection loss can be reduced and the reproducibility can be improved, but also the loss fluctuation which has been a problem in the related art can be suppressed to be extremely small. .

In the present invention equipped with a pressure sensor,
By providing the function of retracting the Z-axis by a desired distance at the same time as detecting the pressure of the connecting surface, the connecting surface can move 90 ° to the core optical axis.
It is possible to eliminate the troubles caused by the contact of the connecting surfaces, which have occurred in the initial alignment of the parts other than the above.

A detailed description will be given below with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a schematic structure of an apparatus for connecting an optical waveguide and an optical fiber according to the present invention. In the figure, reference numeral 1 is an optical waveguide component fixing portion, 4 is an optical waveguide component, 5 is an input fiber component, 7
Is an output fiber component, 8 and 8'is a Z-axis fine movement table, and 9 and 9 '.
Is a pressure sensor for detecting pressure in the Z-axis direction, 10, 10 '
Is the θ-axis that controls the rotation around the Z-axis, and 11 and 11 'are X-axis
The axis fine movement tables 12 and 12 'are Y axis fine movement tables. As described above, in the connecting device of the present invention, the pressure sensor 9, 9'is provided on the Z axis of the stage for aligning the input fiber component 5 and the output fiber component 7, and the connecting surface is connected by this pressure sensor 9, 9 '. The contacting state is detected from the non-contacting state, and the detection position is set to zero, and the function is provided to open a desired distance.

In the step of connecting the optical waveguide and the multi-core fiber component with this apparatus, first, a GI fiber component (not shown) is set in place of the output fiber component 7 in FIG. A GI fiber component having a large core diameter of 50 μm or more can be aligned with the core optical axis of the optical waveguide 4 simply by setting it. In this state, light is incident on the fiber of the input fiber component. At this time, when the fiber component has two or more cores, light is incident on any two ports.

After the incidence, the Z axis 8 is automatically moved toward the optical waveguide component 4. When the end face of the fiber component 5 contacts the end face of the optical waveguide component 4, the pressure sensor 9 detects this,
The Z axis 8 is retracted by a predetermined distance by the interval (ΔT) controller. Therefore, according to the present embodiment, the interval (ΔT) can be managed in this way.

After the connection surface is set to the predetermined interval ΔT, the input fiber component 5 is automatically centered on the X and Y axes so that the light incident on the input fiber component 5 passes through the optical waveguide 4. Since the core dimensions of both parts are as small as 8 to 10 μm, light does not pass through in the initial state with both parts set. Therefore, the normal alignment method is a rough alignment step in which the input fiber component 5 is first moved in the X and Y directions at a pitch of 3 to 5 μm, and alignment is performed until light slightly passes through the core of the optical waveguide 4. , A fine alignment process in which the core optical axes of both components are moved in the X and Y directions at a pitch of 0.1 μm so that the slightly incident light has the maximum light intensity.

In the fine alignment process, in the coarse alignment process when the connecting surface is slanted as shown in FIG. 1, the fiber component 5 and the optical waveguide component 4 are moved even if the fiber component moves in the X and Y directions.
.DELTA.T must be set large so that the connection surfaces of the above will not contact. Although it depends on the dimensional accuracy of each component, the interval ΔT at which the connecting surfaces do not contact each other is 100 μm or more. However, 1
If the thickness is more than 00 μm, the fiber component 5 and the optical waveguide component 4
Even if the core position is optimized, the optical power that passes through is weakened, and it may be impossible to distinguish it from the optical power that propagates through the cladding, and alignment may not be possible.

Therefore, the pressure sensor 9 can detect the contact of the connection surface at the time of aligning, so that the pressure of the contact surface at the time of coarse aligning can be controlled, and if the contact is detected during the coarse aligning, the Z axis 8 is predetermined. It is possible to evacuate the distance and repeat the coarse alignment. That is, it is possible to set the interval (ΔT) to the interval of the fine alignment process even in the coarse alignment process. As a result of repeating the experiment, the interval ΔT is 5 to 10 μm for both the coarse alignment and the fine alignment.
Good alignment was achieved.

After the alignment of the input fiber component 5 and the optical waveguide component 4 is completed, the GI fiber component is moved and the output fiber component 7 is set instead, and the optical waveguide component 4 is set in the same manner as the alignment process of the input fiber component. The output fiber component 7 is aligned.

After the alignment of the input and the output is completed, an adhesive is dropped in the space between the connecting surfaces to fix the connection.

<Experimental Example 1> A 2 × 8 splitter was connected by the apparatus shown in FIG. A 1 × 8 optical waveguide whose connection surface was obliquely polished at 8 degrees was fixed to the optical waveguide component fixing portion, and a GI fiber component was arranged on the output side thereof. As the input fiber component, the connecting surface was polished to 8 degrees, similar to the circuit 1
The core fiber component is set in the fiber component holder provided on the upper part of the Z-axis fine movement table, and the wavelength of 1.3
Light of μm was incident. Further, the connection surface interval was set to 10 μm, and the withdrawal interval during rough alignment was set to 5 μm. Other parameters include a coarse alignment pitch of 3 μm, a fine alignment interval of 10 μm, a fine alignment pitch of 0.1 μm, and G
The threshold value for receiving light by the I fiber was set to 80 μw.

In such a state, automatic centering was started. The connection surface of the input fiber component gradually approached the connection surface of the 1 × 8 optical waveguide by the Z-axis fine movement table, and eventually contacted. At the same time when the pressure sensor detected this, the Z axis retracted. In order to confirm the present invention, the automatic alignment was stopped here, and the retracted interval was measured. As a result, the interval was 10 μm, which was the same as the setting. The amount of light received by the GI fiber was below the threshold value. After confirmation, we started automatic alignment.
The input fiber parts started moving in the X and Y directions at a pitch of 3 μm. Even if the moving range was expanded by 3 μm in the X and Y directions, the amount of light received by the GI fiber remained below the threshold value, but thereafter the pressure sensor started to operate. At the same time, the Z-axis retracted and the pressure sensor stopped operating. After repeating this operation several times, the GI fiber received light above the threshold value. After that, the process shifts to the fine alignment process, and the automatic alignment on the input side is completed at the position where the amount of received light is maximum.

The output side was aligned in the same manner as the input side.
8 aligned on the output fiber component with a pitch of 250 μm
A core fiber component was used. Regarding the alignment on the output side, light was received by the two ports at both ends of the eight fibers to perform alignment. That is, X, Y, and
The θ axis was automatically aligned.

In order to confirm the present invention, the alignment time of input and output excluding the time when the automatic alignment was stopped was 3 minutes and 40 seconds.

After aligning the input and output fiber parts, UV adhesive is dropped on each connection interface and irradiated with ultraviolet rays.
A × 8 splitter was produced.

In this way, 10 1 × 8 splitters were manufactured and the loss was measured. FIG. 2 shows a histogram of connection loss. The average connection loss of total 80 ports is 0.0
The result was a very low splice loss at 8 dB. Further, the fluctuation of the splice loss was 0.14 dB or less even in the maximum splice loss, which was a small fluctuation.

For comparison, a 1 × 8 splitter was manufactured with a conventional connecting device. That is, there is no pressure sensor on the Z axis, and the distance between the connecting surfaces cannot be set arbitrarily.

Prior to the start of rough alignment, the spacing between the connecting surfaces was manually set to 100 μm. The threshold value of the amount of received light is set to 40 μw in consideration of the decrease in the amount of light due to the wide interval. As a result of producing 10 1 × 8 splitters, there were three cases where the alignment was stopped due to the rough alignment without the incidence of light. For these, the parameters were set again and the alignment was performed again.

The alignment time of the parts excluding the parts that were re-aligned was about 25 minutes.

10 1 × 8 splitters manufactured, total 8
FIG. 3 shows a histogram of connection loss at the 0 port. The average connection loss was 0.16 dB, the loss fluctuation was large, and the maximum connection loss was 0.38 dB.

[0038]

As described above, in the device for connecting the optical waveguide component and the fiber component, according to the present invention including the pressure sensor for detecting the contact of the connection surface, the connection surface in the coarse alignment or the fine alignment is provided. Since the interval of can be managed, it becomes possible to set the optimum interval for reducing the connection loss,
Connection loss can be reduced. Also, fluctuations in connection loss can be minimized. Furthermore, since the Z-axis can be controlled by providing the pressure sensor, the Z-axis can be easily automated.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a schematic configuration of a connection device according to the present invention for connecting an optical waveguide and an optical fiber.

FIG. 2 is a histogram of connection loss of a 1 × 8 splitter manufactured by a connection device according to the present invention for connecting an optical waveguide and an optical fiber.

FIG. 3 is a histogram of connection loss of a 1 × 8 splitter manufactured by a conventional connecting device for connecting an optical waveguide and an optical fiber.

FIG. 4 is a schematic diagram for explaining a schematic configuration of a conventional connecting device for connecting an optical waveguide and an optical fiber.

[Explanation of symbols]

 1 Optical Waveguide Component Fixed Part 2 Input Alignment Stage 3 Output Alignment Stage 4 Optical Waveguide Component 5 Input Fiber Component 6 GI Fiber Component 7 Output Fiber Component 8, 8'Z-axis Fine Motion Table 9, 9 'Pressure Sensor 10, 10 'θ-axis 11, 11' X-axis fine movement stage 12, 12 'Y-axis fine movement stage

Claims (2)

[Claims] 1. A method of connecting an optical waveguide and an optical fiber, the first step of arranging the optical waveguide and the core of the optical fiber so that their optical axes coincide with each other; A second step of measuring the contact pressure between the optical waveguide and the optical fiber while moving them closer to each other by moving in the direction along the optical axis, and stopping the movement when the contact pressure is detected; A method of connecting an optical waveguide and an optical fiber, comprising at least a third step of moving the optical waveguide and the optical fiber in a direction opposite to the direction of the movement in the second step by a predetermined amount. 2. A connecting device for an optical waveguide and an optical fiber, which aligns and connects the optical waveguide and the optical fiber while measuring transmitted light of the optical waveguide and the optical fiber, wherein the core of the optical waveguide and the optical fiber And a means for arranging so that the optical axes coincide with each other, a means for moving the optical waveguide and the optical fiber in the direction along the optical axis so as to approach or separate from each other, and A device for connecting an optical waveguide and an optical fiber, comprising means for measuring a contact pressure between the optical waveguide and the optical fiber in the process.