JPS63228108A - Method for mounting and fixing optical fiber to optical connector ferrule - Google Patents

Abstract

PURPOSE:To decrease the eccentricity of an optical fiber guide hole conversely by making positive use of the eccentricity generated by a clearance between the optical fiber guide hole and optical fiber. CONSTITUTION:The optical fiber guide hole 3 is offcentered upward from the center 2 of an optical connector ferrule 1. The optical fiber 5 is mounted on such optical fiber guide hole 3 after the clearance between the optical fiber 5 and the optical fiber guide hole 3 is so offcentered by utilizing the eccentricity thereof that the clearance is larger (a) in the upper part and smaller (b) in the lower part at the time of inserting said optical fiber to the optical fiber guide hole. The fiber is mounted and fixed by taking the predetermined eccentricity and direction of the optical fiber guide hole 3 and the eccentricity and direction of the core of the optical fiber 5 into consideration, using the direction and quantity of the clearance at the time of mounting the optical fiber 5 as parameters and offcentering the clearance in the optimum direction, i.e., the direction where the eccentricity of the core with respect to the optical connector ferrule 1 as the total result is minimized. The eccentricity as a whole is thereby decreased.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method of fixing an optical fiber to an optical connector ferrule that forms the central part of an optical connector that realizes coupling of optical fibers in optical communication. be.

The term "optical connector ferrule" as used in the present invention refers to a member that positions and fixes optical fibers to achieve mutual coupling, and does not necessarily have to be removable, and broadly refers to a member that realizes coupling of optical fibers.

(Prior Art) FIG. 4 is an explanatory diagram of an example of a method for attaching and fixing an optical fiber to a conventional single-fiber optical connector ferrule. As shown in the drawing, insert the optical fiber (
5) and fix with adhesive (7). At this time, in order to insert the optical fiber (5) into the optical fiber guide hole (3), a clearance is required between the two, but it is extremely rare that the clearance is uniform, and it is usually due to the bending of the optical fiber. It was common for clearance to occur due to eccentricity due to other random factors. In the drawings, (2) is the center of the optical connector ferrule, (4) is the center of the optical fiber guide hole, and (8) is the center of the optical fiber.

FIG. 5 is an explanatory diagram of an example of a fixing method for attaching an optical fiber to a conventional multi-core optical connector ferrule. For example, as shown in Figure 2 (a), the multi-fiber optical connector ferrule is made by attaching a reference plate (12) on a groove substrate (II) with optical fiber guide grooves and guide pin grooves formed on the upper surface using a thin film adhesive or the like. Joined and has an optical fiber guide hole inside (■3)
and a guide bin hole 04). The optical fiber (15) is inserted into the optical fiber guide hole (+3) of such a multi-core optical connector ferrule (1G) and fixed with adhesive (ill).
The actual situation is that the optical fiber (15) is fixed without controlling the direction in which the clearance occurs between the optical fiber guide hole (+3) and the optical fiber guide hole (+3).

(Problem to be Solved) As mentioned above, when attaching and fixing an optical fiber to the optical fiber guide hole of a conventional optical connector ferrule, there is no control over the distribution of clearance.
Even if an optical connector ferrule with a small eccentricity of the optical fiber guide hole is created and an optical fiber with a small eccentricity of the core with respect to the cladding is installed there, the eccentricity of the clearance will be added as an uncertain element due to the eccentricity caused by this clearance. Depending on the direction in which the eccentricity occurs, the coupling loss may become significantly worse.

For example, if an optical connector ferrule is supposed to be installed with an eccentricity of 2 μm when there is no clearance eccentricity, but if a clearance eccentricity of 1 μm occurs and this acts in the direction of increasing the eccentricity, the total eccentricity becomes 3 μm, and the original eccentricity of 2 μm increases. The coupling loss of a single mode fiber is about 0.7 dB, but when the eccentricity is 3 μm, the coupling loss is only 1 dB.
There was a problem in that just an increase in μm caused a problem of +5 dB or more, which was worse than the value, and the coupling loss significantly increased.

(Means for solving the problem) The present invention effectively utilizes the eccentricity caused by the clearance that occurs between the conventional optical fiber guide hole and the optical fiber, thereby achieving stable and low loss. The optical fiber mounting method provides a fixing method to realize a single optical connector ferrule.The feature is that the optical fiber is positioned and fixed in close proximity to the optical fiber guide hole of the optical connector ferrule in a certain direction. The reason is that the amount of clearance generated between the optical fiber guide hole and the outer diameter of the optical fiber is eccentrically mounted in the above-mentioned fixed direction.

1 to 3 are explanatory diagrams of specific examples of the optical fiber attachment and fixing method of the present invention.

The first basic concept of the present invention is to actively utilize the amount of eccentricity caused by the clearance, and by using this, conversely to reduce the amount of eccentricity of the optical fiber guide hole.

Figure 1 shows a concrete example based on this idea, where (heavy) is centered on the optical connector ferrule, (3)
is the optical fiber guide hole, (4) is the center of the guide hole, (5)
is an optical fiber, (B) is the center of the optical fiber, and () is an adhesive layer that fixes the optical fiber (5) to the optical fiber guide hole (3). Optical connector ferrule 0 as shown in the figure
) The optical fiber guide hole (3) is offset upward in the figure with respect to the center (2). When inserting and installing the optical fiber (5) into such an optical fiber guide hole (3), the clearance between the optical fiber (5) and the optical fiber guide hole (3) is wider at the top by taking advantage of its eccentricity. (A), the optical fiber guide hole (3) is mounted eccentrically so that the number is smaller at the bottom, and as a result, the amount of eccentricity of the optical fiber guide hole (3) is reduced.

The second basic idea of the present invention is that, for example, a multi-core optical connector ferrule (lO
), by installing the optical fiber close to this reference plate (12), the eccentricity caused by the clearance can be minimized by CI! I). (Refer to Figure 2) Thirdly, the eccentricity of an optical connector ferrule is originally the amount of eccentricity of the optical fiber core with respect to the attached optical connector ferrule that determines the coupling characteristics. Considering the predetermined eccentricity and direction of the optical fiber guide hole and the eccentricity and direction of the optical fiber core, the optical fiber installation is performed in the optimum direction, that is, by using the direction and amount of clearance as parameters. The purpose of the mounting is to set the clearance eccentrically in a direction that minimizes the amount of eccentricity of the core relative to the optical connector ferrule as a result.

FIG. 3 shows a specific example based on this idea, and the same symbols as in FIG. 1 represent the same parts. In the drawing, (8) is the core of the optical fiber (5), and (9) is the center of the core.

Conventionally, when a fixing method is introduced for installation as shown in Figures 1 to 3 above, eccentricity caused by clearance is an uncertain element, and taking a large clearance may lead to a major cause of eccentricity. However, in the method of the present invention, the clearance is grown by properly matching the direction and amount of the optical fiber with the optical connector ferrule to be attached. In addition to making it possible to realize an optical connector ferrule with significantly lower loss than conventional ones, it also eliminates the loss caused by clearance for optical connector ferrules with a large amount of eccentricity, which was previously considered to be defective1. By properly matching the eccentricity, it is possible to create an optical connector ferrule with extremely low loss. For example, for an optical connector ferrule with a large eccentricity, such as an optical fiber guide hole having a large eccentricity of 2 μm, it is possible to use an optical fiber with a small outer diameter to reduce the eccentricity to 0.5 μm or less. It is. Considering that the outer diameter of optical fibers is generally standardized at 125 μm±3 μm, finding a thin optical fiber that produces the above effect is not a big problem when considering mass production manufacturing installation.

The amount of clearance can be determined by measuring the optical fiber guide hole and the outer diameter of the optical fiber to be installed.
The amount and direction of the eccentricity of the optical fiber guide hole can be determined by, for example, optical measurement.

Regarding core eccentricity of an optical fiber, the amount and direction of eccentricity can be determined, for example, by transmitting parallel light from the side of the optical fiber and performing image processing.

In addition, as a method of attaching an optical fiber to an optical fiber guide hole by generating eccentric clearance, for example, as shown in Fig. 6, an optical connector ferrule (20) is set on a ferrule support stand (24), and the optical fiber is inserted from the tip of the optical connector ferrule (20). fiber(
22), and this optical fiber (22) is connected to a pressure member (25) having a pressure spring (2B) and a pressure terminal (27).
By pressing downward with , the clearance in this pressing direction is reduced. It can be seen that the setting should be made so that this and the eccentricity of the optical fiber guide hole are canceled. In the drawing, (21) is an optical fiber, (2
3) is a clamp member for the optical fiber core (22).

l Furthermore, when installing the optical fiber core with eccentricity in mind, for example, the optical connector ferrule and the optical fiber should be able to rotate independently, and the optimal installation can be done by using a computer to determine the direction of pressure in consideration of the amount of clearance generated. After the calculation, the above-mentioned operation can be performed automatically, and it can be fixed with adhesive. At this time, by determining the rotation direction of the optical connector ferrule and optical fiber in advance and inserting them,
It is desirable to take care to avoid torsional stress remaining in the optical fiber.

(Function) As mentioned above, according to the fixing method of the optical fiber of the present invention, the occurrence of eccentricity due to the clearance, which was conventionally considered to be a hindrance, can be effectively caused by the occurrence of eccentricity of the optical fiber guide hole. , the overall amount of eccentricity can be reduced. Normally, in order to insert an optical fiber into an optical fiber guide hole, a clearance of at least about 1 μm is required, but if this is achieved by eccentricity, an eccentric amount of 0.5 μm will occur due to the clearance.

In this case, the amount of eccentricity of the optical fiber guide hole itself of the optical connector ferrule is 1. Even if there is a um, it can be reduced to 0.5 μm in total by properly combining the direction with the amount of clearance eccentricity.

Furthermore, if the overall installation is performed while taking into account the eccentricity and direction of the core relative to the optical fiber club, an optical connector ferrule with smaller eccentricity can be realized. In the above case, if the core is eccentric by 0.5 μm with respect to the cladding, by combining these, the eccentricity of the core with respect to the optical connector ferrule can be made zero. Of course, in order to achieve the above effect, it is necessary to precisely measure each amount of eccentricity, its direction, hole diameter, and outer diameter, and as long as there are errors, it is difficult to completely reduce the amount of eccentricity to zero. It is easy to reduce the eccentricity of the core to less than
, 05 dB or less, and considering that conventional single mode fibers have a good coupling loss of 0.2 to 0.4 dB, it can be seen that the reduction effect is remarkable.

(Example) The inner diameter, amount of eccentricity, and direction of the optical fiber guide hole of an optical connector ferrule whose outer periphery is a metal sleeve and the inside is formed of molded resin were measured by optical processing by observing the end face, and the above optical fiber was measured. The outer diameter of the optical fiber inserted into the bar guide hole, the amount of eccentricity of the core, and its direction were measured. Regarding the eccentric direction, the optical connector ferrule was marked on its flange, and the optical fiber was similarly marked on the clamp member that grips its core part to make it easy to understand.

The eccentricity of the optical fiber guide hole is 01 The maximum eccentricity generated from the clearance is C1 The eccentricity of the optical fiber core is E, and the combination of C and G creates an optical connector ferrule with zero eccentricity. The average loss is 0.1
It was significantly reduced by 1dB.

At this time, G and C were each 0.5 μm. Similarly, when G and C were tested using 1 μm grains, an average of 0.18 dB was achieved, whereas the conventional method that did not take these combinations into account produced an average of 0.45 dB and a maximum of 1 dB or more. In the invention, the level was significantly improved to 0.4 dB or less at maximum.

Furthermore, G=1μm1C=0.5umt E=0.5μ
When installing the optical connector ferrule by taking into consideration the eccentricity of the core, we succeeded in creating an optical connector ferrule with an ultra-low loss of 0.04 dB on average and 0.2 dB or less at maximum.

What is particularly effective about this technology is that the eccentricity of the optical fiber guide hole of the optical connector ferrule is as much as 1 μm, and the optical connector ferrule, which was conventionally unsuitable for creating a low-loss optical connector ferrule, can be assembled with zero loss. .0
This means that it can be used as an extremely good optical connector ferrule with a voltage of less than 5 dB.

In addition, as shown in Figure 2, in the multi-core optical connector ferrule, by pressing it against the reference plate, the average coupling loss with the conventional SMe core is 0.35 dB, but the average coupling loss is 0.19 dB. Considering that this is a multi-core optical connector ferrule made of SMe core, it can be seen that the coupling loss was significantly reduced.

(Effects of the Invention) As described above, according to the fixing method for attaching an optical fiber to the optical connector ferrule of the present invention, the clearance generated between the optical fiber guide hole and the outer diameter of the optical fiber is effectively utilized, and this clearance is By skillfully combining eccentricity and optical fiber guide hole eccentricity, it is possible to easily create an optical connector ferrule with less eccentricity as a result, and furthermore, the optical fiber core can be installed by taking into account the amount of eccentricity and its direction. This makes it possible to further reduce loss. As a result, although conventional optical connector ferrules have had extremely poor coupling loss exceeding 1 dB depending on the direction in which clearance eccentricity occurs, such optical connector ferrules can be prevented from occurring.

Also, conventionally, the eccentricity of the optical fiber guide hole of the optical connector ferrule that can be applied to single mode fiber is 0.5 μm.
However, by applying the method of the present invention, 1
It is now possible to effectively utilize even eccentricity of more than μm.

In this way, in the past, clearance was harmful and caused an uncertain amount of eccentricity, but according to the method of the present invention, this conventional idea is completely new, and the amount of clearance eccentricity is determined. , fiber optic installation becomes one design parameter when the combined technology reduces the average coupling loss to 0.0.
It has become possible to stably produce optical connector ferrules of 5 dB or less on a mass-produced basis.

[Brief explanation of the drawing]

FIGS. 1 and 3 are explanatory diagrams of a specific example of a method for attaching and fixing a single-fiber optical connector ferrule according to the present invention. Figure 2 (A) is a cross-sectional view of an example of a multi-fiber optical connector ferrule, and Figure 2 (B) is an explanatory diagram of a specific example of the fixing method for mounting to the multi-fiber optical connector ferrule in Figure 2 (Gf). be. FIG. 4 and FIG. 5 are both explanatory diagrams of the conventional mounting and fixing method. FIG. 6 is an explanatory diagram of an example of a method for attaching an optical fiber to an optical fiber guide hole by generating an eccentric clearance. DESCRIPTION OF SYMBOLS 1... Optical connector ferrule, 3... Optical fiber guide hole, 5... Optical fiber, 7... Adhesive layer, 8...
...Optical fiber core! 0...Multi-core optical connector ferrule! ! ...Groove board, +2...Reference plate, +
3...Optical fiber guide hole.

Claims (4)

[Claims] (1) In an optical connector ferrule that positions and fixes an optical fiber to realize coupling, by positioning and fixing the optical fiber close to the optical fiber guide hole of the optical connector ferrule in a certain direction, the optical fiber guide hole and the optical fiber can be connected to each other. 1. A method for attaching and fixing an optical fiber to an optical connector ferrule, characterized in that the amount of clearance generated from the diameter is eccentric in the above-mentioned fixed direction. (2) The method for attaching and fixing an optical fiber to an optical connector ferrule according to claim 1, wherein the fixed direction is a direction that reduces the eccentricity of the optical fiber guide hole of the optical connector ferrule. (3) The method for attaching and fixing an optical fiber to an optical connector ferrule according to claim 1, wherein the fixed direction is a direction of a reference plate forming an optical fiber guide hole. (4) The direction in which eccentricity is reduced refers to the eccentricity direction of the core with respect to the cladding of the optical fiber itself, taking into account the eccentricity of the optical fiber guide hole of the optical connector ferrule, the eccentricity of the core with respect to the optical fiber cladding, and the eccentricity caused by the clearance. 3. The method of attaching and fixing an optical fiber to an optical connector ferrule according to claim 2, wherein the direction is such that the total amount of eccentricity is minimized.