JPH0784142A - Fusion splicing method for optical fibers - Google Patents

Abstract

PURPOSE:To provide the fusion splicing method for optical fibers capable of surely and easily lessening connection loss in connection of the optical fibers varying in mode field diameter to each other. CONSTITUTION:One end side 7 of the first optical fiber 1 and one end side 9 of the second optical fiber 2 are fusion spliced. A power meter 10 which is a monitor section is connected to the other side 15 of the optical fiber 2. a feedback control section 17 is connected to the power meter 10. A burner 8 is arranged in a fusion splicing region 5 of the optical fibers 1, 2. The burner 8 is connected to the feedback control section 17 via a burner control section 13. Light is passed to the optical fiber 2 from the optical fiber 1 side. While the intensity of the light emitted from the optical fiber 2 is kept detected and monitored by the power meter 10, the fusion splicing region 5 of the optical fibers 1, 2 is heated by the burner 8 until the light intensity attains the preset value applied to the feedback control section 17, by which the mode fields at the connecting ends of the optical fibers 1, 2 are both expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fusion splicing method for optical fibers having different mode field diameters.

[0002]

2. Description of the Related Art In the field of optical communication, an optical fiber having a different mode field diameter (a diameter of a region where the light intensity is attenuated to 1 / e ² with respect to the light intensity of the central axis of the optical fiber) is used. Fused connections are becoming commonplace.
When coupling optical fibers having different mode field diameters, for example, as shown in FIG. 4A, one end side 7 of the first optical fiber 1 and the first optical fiber 1 have a mode field diameter of One end side 9 of the second optical fiber 2 having a different
Are opposed to each other and are fusion-spliced by the discharge of the arc discharge electrodes 3a and 3b as shown in FIG. The applicant will be
By heating the fusion splicing region 5 of the first optical fiber 1 and the second optical fiber 2 to expand the mode field diameter at the connection end of the first optical fiber 1 and the second optical fiber 2 together. We propose a method to reduce connection loss.

[0003]

However, the first
When heating the fusion spliced region 5 of the second optical fibers 1 and 2, the splice loss cannot be effectively reduced unless the conditions such as heating time and temperature are appropriate, and conventionally, adjustment of those conditions is not possible. Since there is no means to judge during the mode field expansion process whether or not it is properly performed, the condition adjustment may not be properly performed, and in that case, the connection loss of the optical fibers 1 and 2 becomes large. There was a problem. For example, if the types of optical fibers 1 and 2 to be connected are different or the heating temperature is not stable, the mode field may be expanded appropriately even if the heating process is performed for the same time, and it is sufficient. In some cases, the connection loss may not be expanded, or the connection loss may increase due to excessive expansion. Therefore, the connection loss of the optical fibers 1 and 2 may vary depending on the connection, and the optical fibers 1 and 2 may be used for optical communication. The yield of good connection products was poor when used as.

The present invention has been made in order to solve the above problems, and an object thereof is to easily reduce the splice loss in splicing between optical fibers having different mode field diameters. To provide a fusion splicing method.

[0005]

In order to achieve the above object, the present invention is constructed as follows. That is, according to the present invention, one end side of the first optical fiber and one end side of a second optical fiber having a mode field diameter different from that of the first optical fiber are fusion-spliced, and the other end of the second optical fiber is A monitor unit for detecting and monitoring the light intensity is provided on the side, and after the first optical fiber and the second optical fiber are fusion-spliced, light is passed from the first optical fiber side to the second optical fiber. While the light intensity of the light emitted from the second optical fiber is detected and monitored by the monitor unit, the fusion of the first optical fiber and the second optical fiber is performed until the light intensity exceeds a preset value. The present invention is characterized in that the connecting / disconnecting region is heated to expand both the mode fields at the connecting ends of the first optical fiber and the second optical fiber.

[0006]

In the present invention having the above-mentioned structure, light is passed from the first optical fiber side to the second optical fiber, and the intensity of the light emitted from the second optical fiber is detected and monitored by the monitor section. , The fusion splicing region of the first optical fiber and the second optical fiber is heated until the light intensity becomes equal to or higher than a preset value, so that the connecting end portion of the first optical fiber and the second optical fiber is heated. The mode field in is expanded together,
When the size of the mode field is expanded to an appropriate size, the heating of the fusion spliced regions of the first and second optical fibers is completed. Then, since the mode fields of the first and second optical fibers are enlarged and connected to an appropriate size, the connection loss between the first and second optical fibers is surely reduced.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same reference numerals will be given to the same names as those in the conventional example, and the detailed description thereof will be omitted.
FIG. 1 shows a first embodiment of a fusion splicing apparatus for splicing optical fibers by using the fusion splicing method for optical fibers according to the present invention in a state where optical fibers 1 and 2 are attached.
In the figure, the optical fibers 1 and 2 are arranged such that one end side 7 of the first optical fiber 1 and one end side 9 of the second optical fiber 2 are opposed to each other as in the conventional example and are melted by the arc discharge electrodes 3a and 3b. They are connected to each other by welding, and after fusion connection, they are set in a heating device equipped with a burner. The mode field of the first optical fiber 1 is a perfect circle with a diameter of 9.5 μm, and the mode field of the second optical fiber 2 is 13 μm in major axis and 6.2 in minor axis.
The mode fields of both optical fibers 1 and 2 are different in size and shape.

A laser diode 4 is connected to the other end side 14 of the first optical fiber, and a power meter 10 as a monitor is connected to the other end side 15 of the second optical fiber 2. A feedback controller 17 is connected to the power meter 10. A burner 8 is arranged in the fusion splicing area 5 of the first and second optical fibers 1 and 2, and the burner 8 is connected to a burner controller 13, which in turn is connected to the feedback controller 17. Has been done.

The laser diode 4, which functions as a light emitting device, emits laser light (optical signal). The emitted light is incident on the first optical fiber 1 and passes through the first optical fiber 1 to reach the first optical fiber 1. First optical fiber side to second optical fiber 2
Through the optical fiber 2, the light is emitted from the end side 15 of the second optical fiber 2, and enters the power meter 10.

The power meter 10 detects the optical signal, converts it into an electric signal and monitors the light intensity of the emitted light moment by moment,
The monitor signal is added to the feedback control unit 17. The feedback control unit 17 includes the signal comparison unit 11
And a memory unit 12, and a preset value of light intensity is input to the memory unit 12. Signal comparison unit 11
Is the set value input to the memory unit 12 and the power meter 10
The monitor signal of the light intensity applied to the signal comparison unit 11 from the above is compared, and when the light intensity emitted from the second optical fiber 2 exceeds the set value input to the memory unit 12, the heating is terminated. The heating end signal (OFF signal) is applied to the burner control unit 13, and the burner control unit 13 stops the burner 8 in response to the heating end signal applied from the signal comparison unit 11, It is designed to finish heating.

When the optical fibers 1 and 2 are connected by the optical fiber fusion splicing method of the present invention, the first and second optical fibers 1 and 2 are heated by the burner 8 after the fusion splicing,
The mode field diameters of the optical fibers 1 and 2 are both expanded in the fusion splicing region 5, but at this time, laser light is emitted from the laser diode 4 to be incident on the first optical fiber 1. When the light intensity of the light emitted from the end side 15 of the optical fiber 2 is measured by passing light from the side of the first optical fiber 1 to the second optical fiber 2, the light intensity after heating gradually increases.

FIG. 2 shows the first and second optical fibers 1 and 2.
The experimental results for obtaining the relationship between the heating time of the fusion spliced region 5 and the light intensity (emission power) of the emitted light are shown. As shown in the figure, the emission power increases as the heating time increases, and conversely decreases after heating for a certain time or longer.

This means that both the mode fields at the connection ends of the first and second optical fibers 1 and 2 are expanded by heating, but the rate of expansion is the mode fields of the optical fibers 1 and 2. However, in the beginning, the area of the overlapping portions of the mode fields of the optical fibers 1 and 2 is expanded so that the area ratio is increased, and as a result, the connection loss of the optical fibers 1 and 2 is reduced and When the field expansion state is optimum, that is, when the ratio of the overlapping portions of the mode fields of the optical fibers 1 and 2 increases and the mode field diameters come close to each other, the connection loss of the optical fibers 1 and 2 becomes the smallest. However, when the state is further expanded beyond that state, the light is not confined in the core, and the light goes out of the optical fibers 1 and 2.

Therefore, by appropriately setting the mode field expansion state of the optical fibers 1 and 2, the connection loss is, for example, 0.2.
In order to keep it below dB, the laser diode 4
When the laser beam emitted from is −0.3 dBm, the set value of −0.5 dBm is input to the memory unit 12, and the light intensity emitted from the second optical fiber 2 and detected by the power meter 10 is If the heating by the burner 8 is terminated when the temperature reaches −0.5 dBm or more, the mode fields of the optical fibers 1 and 2 are expanded to an appropriate size, and the expansion is completed in that state to connect the optical fibers. The connection loss of 1 and 2 can be set to a small value of 0.2 dB or less.

In this way, the optical fiber 1,
The setting value is determined so that the connection loss of No. 2 is 0.2 dB or less, and the setting value is input to the memory unit 12.
While passing light through the optical fiber 2, the optical fiber 1,
When the fusion splicing region 5 of 2 was heated to expand the mode fields of the connection ends of the optical fibers 1 and 2, the optical fibers 1 and 2 could be connected with a small connection loss of 0.20 dB. . Similarly, when connecting the other optical fibers 1 and 2, the setting value is determined so that the connection loss of the optical fibers 1 and 2 is 0.2 dB or less.
Inputting into 12, heating the light emitted from the optical fiber 2 while passing it through the optical fibers 1 and 2 to a value above a set value and expanding the mode field, 9 out of 9 times It was possible to connect with a connection loss as small as 0.20 dB.

According to this embodiment, after the first optical fiber 1 and the second optical fiber 2 are fusion-spliced, light is passed from the first optical fiber 1 side to the second optical fiber 2 and then the second optical fiber 2 is passed. While the intensity of the light emitted from the optical fiber 2 is detected and monitored by the power meter 10, the first optical fiber 1 and the second optical fiber 2 until the optical intensity exceeds a preset value.
In order to heat the fusion splicing region 5 with and to expand the mode field at the connection ends of the first optical fiber 1 and the second optical fiber 2, the mode fields are connected in a properly expanded state. Therefore, it is possible to easily make a connection with surely small connection loss such that the light intensity is equal to or higher than a preset value.

That is, the light intensity of the emitted light emitted from the second optical fiber 2 is monitored every moment, and the burner 8 heats the light until the light intensity exceeds a preset value. Even if the types of fibers 1 and 2 are different or the temperature of the burner 8 is not stable,
The mode fields at the fusion spliced portions of the second optical fibers 1 and 2 are both expanded to an appropriate size, and heating is terminated in that state, so that the connection is surely made with a small connection loss.

FIG. 3 shows a second embodiment of the fusion splicing apparatus for splicing the optical fibers by using the fusion splicing method of the optical fibers of the present invention in a state where the optical fibers 1 and 2 are attached. . The main difference between the second embodiment and the first embodiment is that
That is, the arc discharge electrodes 3a and 3b are used as a heating system for heating the fusion spliced region 5 of the optical fibers 1 and 2. The arc discharge electrodes 3a and 3b are connected to the discharge control unit 20, and the discharge control unit 20 is connected to the feedback control unit 17 as in the first embodiment.

In the second embodiment, after the first and second optical fibers 1 and 2 are fusion-spliced by the arc discharge electrodes 3a and 3b, the first optical fiber is processed in the same manner as in the first embodiment. 1
While measuring the intensity of the light emitted from the second optical fiber 2 by passing the light from the side to the second optical fiber 2, the arc discharge electrode 3 until the light intensity reaches a preset value or more.
The connection region 5 of the first and second optical fibers 1 and 2 is heated by a and 3b to expand the mode field at the connection ends of the first and second optical fibers 1 and 2.

The second embodiment has the same effect as that of the first embodiment, and further, in the second embodiment, the arc discharge electrode 3 is used.
Since the first optical fiber 1 and the second optical fiber 2 are fusion spliced by a and 3b and then continuously heated to expand the mode field, it is not possible to move the optical fibers 1 and 2. Connection can be made more effectively. Actually, the set value was determined so that the splice loss was 0.6 dB or less, the set value was input to the memory unit 12, and the fusion splicing of the optical fibers 1 and 2 was performed 10 times. The connection loss was 0.60 dB at all times.

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in the above embodiment, the fusion spliced region 5 of the optical fibers 1 and 2 was heated by the burner 8 and the arc discharge electrodes 3a and 3b, but the heating system is not particularly limited, and the burner 8 and the arc can be used. The heating may be performed by a heating system other than the discharge electrodes 3a and 3b.

In the above embodiment, the mode field was expanded only by heating with the burner 8 and the arc discharge electrodes 3a and 3b. However, at least one side of the optical fibers 1 and 2 is moved in the drawing direction while being heated. The fusion splicing region 5 may be melt-stretched to expand the mode field.

Further, in the above embodiment, the burner controller 1
3, or a feedback control unit 17 is provided between the discharge control unit 20 and the power meter 10, and the light intensity detected by the power meter 10 is previously stored in the memory unit 12 of the feedback control unit 17.
When the value exceeds the set value input to the burner control section 13 or the discharge control section 20, the burner 8 or the arc discharge electrodes 3a and 3b finish the heating, but the feedback control section 17 is not always provided. Not limited to, power meter
When a person observes the 10 monitors and the light intensity becomes equal to or higher than the set value, the burner 8 or the like may be manually stopped to end the heating.

Further, in the above-mentioned embodiment, the laser diode 4 emits light to the optical fibers 1 and 2 and allows the light to pass through the optical fibers 1 and 2, but the light emitting device other than the laser diode 4 is used. And emits the light from the optical fiber 1,
You can pass it through 2.

Further, in the above embodiment, the connection loss is 0.2.
Memory unit 12 so that it is below dB or below 0.6 dB
Although the set value to be input to is determined, the set value to be input is not particularly limited and may be set appropriately according to the specifications of the optical fibers 1 and 2. Further, in the above embodiment, only the intensity of the light emitted from the optical fiber 2 was measured,
The optical fiber 2 detects the intensity of light emitted from the light emitting device.
A monitor is provided to monitor the value of the intensity of light emitted from the device, which is subtracted from the intensity of light emitted from the light emitting device, and the optical fiber is used until the value monitored by the monitor falls below a preset splice loss value. The fusion splicing regions 5 of 1 and 2 may be heated.

Further, in the above embodiment, the mode field of the first optical fiber 1 is a perfect circle and the mode field of the second optical fiber 2 is an ellipse. However, conversely, the first optical fiber is used. The mode field of 1 may be an ellipse and the mode field of the second optical fiber 2 may be a perfect circle, and both of the mode fields of the optical fibers 1 and 2 may be an ellipse or both may be perfect circles. Further, the size of the mode field diameter of the first optical fiber 1 and the second optical fiber 2 is not particularly limited, and it can be used for fusion splicing of optical fibers 1 and 2 having mode fields of various different diameters. The present invention can be applied.

[0027]

According to the present invention, light is passed from the first optical fiber side to the second optical fiber, and the monitor unit detects and monitors the light intensity of the light emitted from the second optical fiber. However, until the light intensity exceeds a preset value, the first
Of the first and second optical fibers for heating the fusion spliced region between the first optical fiber and the second optical fiber to expand the mode field at the connection end of the first optical fiber and the second optical fiber together. Both the mode fields of the optical fibers are expanded to an appropriate state, and it is possible to easily make a connection with surely small connection loss. Therefore, the connected optical fibers 1, 2
Even if the type is different or the heating temperature of the heating system is not stable, a connection with a small connection loss is always made so that the light intensity is equal to or higher than a preset value, and the fusion of the optical fiber of the present invention is performed. If the optical fibers are connected by the connection method, the connection can be always reliable even when the connected optical fibers are used for optical communication.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a fusion splicing apparatus for splicing optical fibers by a fusion splicing method for optical fibers according to the present invention, with attached optical fibers 1 and 2. FIG.

FIG. 2 is a graph showing an example of the relationship between the heating time of the fusion splicing regions of the first and second optical fibers and the emission power detected and monitored by the power meter 10.

FIG. 3 is a configuration diagram showing a second embodiment of the fusion splicing apparatus for splicing optical fibers by the fusion splicing method for optical fibers according to the present invention, with the optical fibers 1 and 2 attached.

FIG. 4 is an explanatory diagram showing an example of a fusion splicing process of optical fibers.

[Explanation of symbols]

 1 First Optical Fiber 2 Second Optical Fiber 3a, 3b Discharge Electrode 5 Fusion Splicing Area 8 Burner 10 Power Meter

Claims (1)

[Claims] 1. One end side of a first optical fiber and one end side of a second optical fiber having a mode field diameter different from that of the first optical fiber are fusion-spliced, and the other end side of the second optical fiber. Is provided with a monitor unit for detecting and monitoring the light intensity.
After the fusion splicing of the optical fiber and the second optical fiber, the light is passed from the first optical fiber side to the second optical fiber, and the light intensity of the light emitted from the second optical fiber is detected by the monitor unit. Then, while monitoring, the fusion splicing region of the first optical fiber and the second optical fiber is heated until the light intensity becomes equal to or higher than a preset value, and the first optical fiber and the second optical fiber are heated.
A method for fusion splicing optical fibers, characterized in that the mode field at the splicing end portion of the optical fiber is expanded together.