WO2024143179A1 - Ferrule for optical fiber and ferrule with optical fiber - Google Patents

Abstract

This ferrule for an optical fiber comprises: a housing which is molded from a resin and has a connection end surface and a plurality of wall surfaces surrounding the connection end surface; a fiber insertion hole which is open to the connection end surface and into which an optical fiber can be inserted; and a first gate mark which is a mark of a gate formed on a first gate surface that is one of the plurality of wall surfaces, and in which the resin is filled into a mold for molding the housing. The fiber insertion hole has a linear first linear portion and an arc-shaped first arc portion in a horizontal cross-section orthogonal to the center axis of the fiber insertion hole, and the first linear portion is parallel to the first gate surface.

Description

Ferrules for optical fibers and ferrules with optical fibers

The present invention relates to a ferrule for an optical fiber and a ferrule with an optical fiber.
This application claims priority based on Japanese Patent Application No. 2022-211239, filed on December 28, 2022, the contents of which are incorporated herein by reference.

Patent Document 1 discloses a ferrule for optical fibers having a fiber insertion hole. In cross section, the fiber insertion hole has a D-shape that includes a straight portion and an arc portion. In this ferrule, the straight portion suppresses the rotation of the optical fiber inside the fiber insertion hole, thereby positioning the optical fiber in the circumferential direction of the fiber insertion hole.

Japanese Patent Publication No. 2014-225036

Ferrules molded from resin can undergo unintended deformation due to the shrinkage of the resin during the molding process. For example, if such deformation occurs in the ferrule described in Patent Document 1, the fiber insertion hole may deform into a shape different from the desired shape, potentially reducing the accuracy of positioning between the fiber insertion hole and the optical fiber.

The present invention was made in consideration of these circumstances, and aims to provide a ferrule for optical fiber and a ferrule with optical fiber that can suppress a decrease in the accuracy of positioning between the fiber insertion hole and the optical fiber caused by deformation of the fiber insertion hole during the molding process.

In order to solve the above problem, the optical fiber ferrule according to aspect 1 of the present invention comprises a housing molded from resin, the housing having a connection end face and a plurality of wall faces surrounding the connection end face, a fiber insertion hole that opens into the connection end face and through which an optical fiber can be inserted, and a first gate mark that is a mark of a gate that filled the resin into a mold for molding the housing and is formed on a first gate face that is one of the plurality of wall faces, the fiber insertion hole having a first straight line portion that is linear and a first arc portion that is arcuate in a cross section perpendicular to the central axis of the fiber insertion hole, and the first straight line portion is parallel to the first gate face.

Aspect 2 of the present invention is the optical fiber ferrule of aspect 1, in which the first straight portion is located between the first gate surface and the first arc portion in a direction perpendicular to the first gate surface.

Aspect 3 of the present invention is an optical fiber ferrule according to aspect 1 or 2, further comprising a second gate mark formed on a second gate surface located on the opposite side of the first gate surface, which is one of the plurality of wall surfaces, and which is a gate mark formed by filling the resin into a mold for molding the housing, and the fiber insertion hole further comprises, in the cross section, a second straight line portion that is linear and located on the opposite side of the first straight line portion, and a second arc portion that is arc-shaped, and the second straight line portion is parallel to the second gate surface.

The ferrule with optical fiber according to aspect 4 of the present invention comprises an optical fiber ferrule according to any one of aspects 1 to 3, and a plurality of optical fibers inserted into the fiber insertion holes.

The above aspects of the present invention provide a ferrule for optical fiber and a ferrule with optical fiber that can suppress a decrease in the accuracy of positioning between the fiber insertion hole and the optical fiber caused by deformation of the fiber insertion hole during the molding process.

FIG. 2 is a perspective view showing the ferrule with optical fiber according to the first embodiment. 3A to 3C are diagrams illustrating an example of a molding process for the optical fiber ferrule according to the first embodiment. FIG. 2B is a diagram showing a state subsequent to FIG. 2A. 2 is a perspective view showing a plurality of optical fibers extracted from the ferrule with optical fiber shown in FIG. 1 . 4 is a cross-sectional view taken along line IV-IV shown in FIG. FIG. 1 is a cross-sectional view showing a conventional ferrule with an optical fiber. FIG. 4 is a cross-sectional view showing a ferrule with an optical fiber according to a modified example of the first embodiment. FIG. 4 is a diagram showing an optical fiber ferrule according to a second embodiment. FIG. 4 is a cross-sectional view showing an optical fiber ferrule according to a second embodiment.

First Embodiment
Hereinafter, a ferrule for optical fiber and a ferrule with an optical fiber according to a first embodiment will be described with reference to the drawings.

As shown in FIG. 1, the ferrule with optical fiber 1 according to this embodiment includes a ferrule (a ferrule for optical fiber) 10, a plurality of optical fibers 20, and two positioning pins 30. The ferrule with optical fiber 1 does not necessarily have to include the positioning pins 30. The ferrule with optical fiber 1, together with, for example, a biasing member for biasing the ferrule 10, constitutes an optical connector (not shown).

The ferrule 10 comprises a housing H molded from resin and a gate mark 40. The housing H has a connection end face 10a, a rear end face 10b, a fiber insertion hole 11, and two positioning holes 12. The connection end face 10a is the surface that is butted against another ferrule when the ferrule 10 is connected to the other ferrule.

The fiber insertion hole 11 and the two positioning holes 12 open in the connection end face 10a. The fiber insertion hole 11 according to this embodiment is arranged between the two positioning holes 12 in the connection end face 10a. An introduction hole (not shown) that communicates with the connection end face 10a opens in the rear end face 10b. A plurality of optical fibers 20 are introduced into the fiber insertion hole 11 in the ferrule 10 through the introduction hole. A positioning pin 30 is inserted into each of the two positioning holes 12. If the ferrule 1 with optical fiber does not have a positioning pin 30, the housing H does not need to have a positioning hole 12. The housing H may have an injection hole that communicates with the internal space of the housing H and the fiber insertion hole 11. In this case, adhesive can be injected into the internal space of the housing H and the fiber insertion hole 11 through the injection hole.

(Direction definition)
In this specification, the direction parallel to the central axis O of the fiber insertion hole 11 is referred to as the Z direction, the axial direction, or the longitudinal direction Z. One direction perpendicular to the longitudinal direction Z is referred to as the first direction X. In this embodiment, the first direction X is also the direction in which the two positioning holes 12 are arranged. One direction along the first direction X is referred to as the +X direction or the right direction. The direction opposite to the +X direction is referred to as the -X direction or the left direction. The direction perpendicular to both the longitudinal direction Z and the first direction X is referred to as the second direction Y. The direction from the rear end face 10b of the ferrule 10 toward the connection end face 10a along the longitudinal direction Z is referred to as the +Z direction, the front, or the tip side. The direction opposite to the +Z direction is referred to as the -Z direction, the rear, or the base end side. The direction perpendicular to the central axis O as viewed from the longitudinal direction Z is referred to as the radial direction. A direction approaching the central axis O along the radial direction is referred to as the radially inner direction. A direction moving away from the central axis O as viewed from the longitudinal direction Z is referred to as the radially outer direction. A direction going around the central axis O as viewed from the longitudinal direction Z is referred to as the circumferential direction.
A cross section perpendicular to the longitudinal direction Z is referred to as a transverse cross section. That is, a transverse cross section is a cross section extending along the first direction X and the second direction Y.

As shown in FIG. 1, the housing H according to this embodiment includes a connection portion H1 and a flange portion H2. The flange portion H2 is located behind the connection portion H1. In the first direction X and the second direction Y, the dimensions of the flange portion H2 are greater than the dimensions of the connection portion H1. The connection portion H1 and the flange portion H2 are integrally molded from the same resin.

In this embodiment, the connection portion H1 and the flange portion H2 each have a rectangular parallelepiped shape. In addition to the connection end surface 10a described above, the connection portion H1 has four wall surfaces (connection portion wall surfaces) 11s1. The four wall surfaces 11s1 surround the connection end surface 10a when viewed from the longitudinal direction Z. In addition to the rear end surface 10b described above, the flange portion H2 has a flange surface 10c and four wall surfaces (flange portion wall surfaces) 11s2. The flange surface 10c faces forward. The flange surface 10c has a ring shape and is connected to the four wall surfaces 11s1 of the connection portion H1. The four wall surfaces 11s2 surround the connection end surface 10a when viewed from the longitudinal direction Z. Each wall surface 11s1, 11s2 faces radially outward and extends in a direction intersecting the connection end surface 10a.

As shown in FIG. 1, at least one gate mark 40 is formed on the outer peripheral surface of the ferrule 10. Hereinafter, the surface on which the gate mark 40 is formed will be referred to as the gate surface S. In this embodiment, the ferrule 1 with optical fiber has only one gate surface S (first gate surface S1) and only one gate mark 40 (first gate mark 41). In the illustrated example, of the four wall surfaces 11s2 that the flange portion H2 has, the one wall surface 11s2 facing leftward (-X side) corresponds to the gate surface S.

2A and 2B are diagrams showing an example of the molding process of the ferrule 10. The process of forming the gate mark 40 will be described using these figures 2A and 2B. As shown in Figure 2A, when manufacturing the ferrule 10, a mold 50 is used to mold (injection mold) the ferrule 10 with resin. The mold 50 has an internal space 51 having a shape substantially the same as the outer shape of the ferrule 10, a gate 52 opening into the internal space 51, and a runner 53 communicating with the gate 52. The internal space 51 is filled with heated and melted resin through the runner 53 and the gate 52. Hereinafter, the direction in which the resin is filled from the gate 52 into the internal space 51 is referred to as the filling direction, and the direction perpendicular to the filling direction in the cross section is referred to as the intersecting direction. In this embodiment, the filling direction is the first direction X, and the intersecting direction is the second direction Y.

The molten resin filled in the internal space 51 is cooled and solidified. After that, the resin solidified in the internal space 51 (casing H of the ferrule 10), the resin solidified at the gate 52 (gate portion G), and the resin solidified at the runner 53 (runner portion R) are removed from the mold 50. At this time, the casing H of the ferrule 10, the gate portion G, and the runner portion R are integrated with each other. Then, for example, the gate portion G is cut with nippers or the like to remove the gate portion G and the runner portion R, and the casing H is obtained. At this time, as shown in FIG. 2B, a part of the gate portion G remains in the casing H. The remaining part is the gate mark 40. In other words, the gate mark 40 is a mark of the gate 52. The gate mark 40 has a shape that protrudes from the wall surface 11s2 of the casing H in the filling direction (first direction X), for example.

FIG. 3 is a diagram showing the multiple optical fibers 20 shown in FIG. 1. As shown in FIG. 3, the ferrule with optical fiber 1 according to this embodiment has four optical fibers 20. However, the number of optical fibers 20 can be changed as appropriate so long as it is one or more. Each optical fiber 20 has a bare fiber 21 and a coating 22.

The bare fiber 21 is made of, for example, quartz glass. The coating 22 partially covers the bare fiber 21 and serves to protect the bare fiber 21. The coating 22 is made of, for example, resin. For example, the material of the coating 22 may be a UV-curable resin. The bare fiber 21 is inserted into the fiber insertion hole 11 of the ferrule 10. The bare fiber 21 (optical fiber 20) may be fixed to the fiber insertion hole 11 by an adhesive (not shown).

The bare fiber 21 has a small diameter portion 21a and a large diameter portion 21b. The outer diameter of the small diameter portion 21a is smaller than the outer diameter of the large diameter portion 21b. In this embodiment, the small diameter portion 21a is inserted into the fiber insertion hole 11 of the ferrule 10.

Figure 4 is a cross-sectional view of the ferrule 10. More specifically, Figure 4 is a cross-sectional view showing the vicinity of the fiber insertion hole 11 at the connection end face 10a. As shown in Figure 4, the bare fiber 21 has a core 21c and a clad 21d. The clad 21d is arranged to surround the core 21c. The refractive index of the clad 21d is lower than the refractive index of the core 21c. Therefore, the optical fiber 20 can confine light inside the core 21c.

As shown in FIG. 4, the fiber insertion hole 11 in this embodiment has one arc portion 11a (first arc portion 11a1) and one straight portion 11b (first straight portion 11b1). The arc portion 11a extends in an arc shape in a cross-sectional view. The straight portion 11b extends in a straight line in a cross-sectional view. In other words, the fiber insertion hole 11 is D-shaped in a cross-sectional view. The straight portion 11b extends parallel to the gate surface S. In other words, the straight portion 11b extends in the second direction Y in a cross-sectional view. In addition, in a direction perpendicular to the gate surface S (first direction X), the straight portion 11b is located between the gate surface S and the arc portion 11a. In other words, the gate surface S, the straight portion 11b, and the arc portion 11a are arranged in this order in the first direction X. In other words, the straight section 11b in this embodiment is formed on the left side (-X side) of the fiber insertion hole 11.

Of the four bare fibers 21, two bare fibers 21 abut both the arc portion 11a and the straight portion 11b. The remaining two bare fibers 21 abut the arc portion 11a but not the straight portion 11b. These four bare fibers 21 abut against the inner surface of the fiber insertion hole 11 as described above, and are positioned within the fiber insertion hole 11 with adjacent bare fibers 21 abutting against each other. In this way, the four bare fibers 21 are arranged in a square on the inner surface of the fiber insertion hole 11.

Next, the operation of the ferrule 1 with optical fiber and the ferrule 10 configured as described above will be explained.

　Conventionally, ferrules are known that have a fiber insertion hole that is D-shaped in cross section. In such ferrules, the straight portion prevents the optical fiber from rotating inside the fiber insertion hole, thereby positioning the fiber insertion hole and the optical fiber in the circumferential direction.

However, in ferrules molded from resin, unintended deformation can occur due to the shrinkage of the resin during the molding process. Figure 5 shows an example of such deformation that occurs in a conventional ferrule.

To facilitate the explanation, the first region R1, the second region R2, and a pair of third regions R3 are defined below. The first region R1 is a region adjacent to the left side (-X side) of the fiber insertion hole 11. In other words, the first region R1 is a region adjacent to the gate surface S side of the fiber insertion hole 11. The second region R2 is a region adjacent to the right side (+X side) of the fiber insertion hole 11. In other words, the second region R2 is a region located on the opposite side of the first region R1 with respect to the fiber insertion hole 11. The pair of third regions R3 are regions adjacent to both sides of the fiber insertion hole 11 in the intersecting direction (second direction Y). In the filling direction (first direction X), the first region R1 is closer to the gate surface S than the second region R2. In other words, the distance between the first region R1 and the gate surface S is shorter than the distance between the second region R2 and the gate surface S.

Generally, when the resin poured into the mold cools and solidifies, the resin shrinks more in the third region R3 than in the first region R1 and the second region R2. That is, during the molding process, the ferrule shrinks more in the intersecting direction (second direction Y) than in the filling direction (first direction X). Therefore, when the straight portion 11b faces the intersecting direction, the arc portion 11a deforms into an elliptical arc whose major axis extends in the first direction X. This type of deformation can cause a gap to form between the bare fiber 21 and the fiber insertion hole 11, reducing the positioning accuracy of the bare fiber 21 in the fiber insertion hole 11.

In consideration of this problem, in the ferrule 10 according to this embodiment, as shown in FIG. 4, the straight portion 11b of the fiber insertion hole 11 faces the filling direction (first direction X). That is, the straight portion 11b extends parallel to the gate surface S. This makes it less likely for the arc portion 11a to deform into an elliptical shape compared to, for example, a case in which the straight portion 11b faces the intersecting direction (second direction Y). Therefore, it is possible to suppress a decrease in the positioning accuracy of the bare fiber 21 in the fiber insertion hole 11.

As shown in the example of FIG. 6, the straight portion 11b may be disposed on the opposite side of the gate surface S (see FIG. 1) in the first direction X. That is, the straight portion 11b may be formed on the right side (+X side) of the fiber insertion hole 11. In other words, the gate surface S, the arc portion 11a, and the straight portion 11b may be arranged in this order in the first direction X. Even in this case, since the straight portion 11b faces the filling direction, it is possible to suppress a decrease in the positioning accuracy of the bare fiber 21 in the fiber insertion hole 11 compared to the case where the straight portion 11b faces the intersecting direction. However, the configuration of FIG. 4 in which the straight portion 11b is adjacent to the first region R1 is more preferable than the configuration shown in FIG. 6 in which the straight portion 11b is adjacent to the second region R2. The reason for this is explained below.

In the configuration of FIG. 4 in which the straight portion 11b is adjacent to the first region R1, the arc portion 11a is adjacent to the second region R2 and a pair of third regions R3. On the other hand, in the configuration of FIG. 6 in which the straight portion 11b is adjacent to the second region R2, the arc portion 11a is adjacent to the first region R1 and a pair of third regions R3. Here, generally, the shrinkage of the resin in the first region R1 is smaller than that in the second region R2. Therefore, the difference in the amount of shrinkage of the resin between the first region R1 and the third region R3 is greater than the difference in the amount of shrinkage of the resin between the second region R2 and the third region R3. Therefore, the configuration of FIG. 4 in which the arc portion 11a is adjacent to the second region R2 and the third region R3 can suppress the variation in the amount of shrinkage of the resin in the part adjacent to the arc portion 11a more than the configuration of FIG. 6 in which the arc portion 11a is adjacent to the first region R1 and the third region R3. This makes the shape of the arc portion 11a closer to a perfect circle, and further reduces the deterioration of the positioning accuracy of the bare fiber 21.

The resin used to mold the housing H of the ferrule 10 generally contains a glass filler. The molecules that make up the glass filler have a columnar shape. When the housing H is molded using the mold 50, the flow of the resin filled into the internal space 51 from the gate 52 causes the columnar molecules to solidify in a state where they extend approximately in the filling direction (first direction X). Therefore, in the molded housing H, the strength in the filling direction (first direction X) is higher than the strength in the intersecting direction (second direction Y). In the ferrule 10 according to this embodiment, the straight portion 11b faces the filling direction (first direction X), so that deformation of the straight portion 11b after molding of the housing H can be suppressed compared to, for example, a case in which the straight portion 11b is parallel to the filling direction. For example, the curvature of the straight portion 11b caused by the force of the bare fiber 21 pressing against the fiber insertion hole 11 can be suppressed.

As described above, the ferrule (optical fiber ferrule) 10 according to this embodiment has a connection end surface 10a and a plurality of wall surfaces 11s2 surrounding the connection end surface 10a, and includes a housing H molded from resin, a fiber insertion hole 11 that opens in the connection end surface 10a and through which an optical fiber 20 can be inserted, and a gate mark 40 (first gate mark 41) that is a mark of a gate 52 that filled a mold 50 for molding the housing H with resin, formed on a gate surface S (first gate surface S1) that is one of the plurality of wall surfaces 11s2, and the fiber insertion hole 11 has a straight straight portion 11b (first straight portion 11b1) and an arc-shaped arc portion 11a (first arc portion 11a1) in a cross section perpendicular to the central axis O of the fiber insertion hole 11, and the straight portion 11b is parallel to the gate surface S.

This configuration makes it possible to suppress unintended deformation of the fiber insertion hole 11 during the molding process of the ferrule 10, compared to, for example, a case in which the straight portion 11b faces the intersecting direction (second direction Y). More specifically, the arc portion 11a is less likely to deform into an elliptical shape. This makes it possible to suppress a decrease in the positioning accuracy of the bare fiber 21 within the fiber insertion hole 11. Furthermore, when the ferrule 10 is molded using a resin containing glass filler, it is possible to suppress deformation of the straight portion 11b after molding, such as bending of the straight portion 11b due to the pressing force of the bare fiber 21.

In addition, the straight portion 11b is located between the gate surface S and the arc portion 11a in a direction perpendicular to the gate surface S. With this configuration, the decrease in the positioning accuracy of the bare fiber 21 can be further suppressed compared to when the straight portion 11b is located on the opposite side of the gate surface S.

The ferrule with optical fiber 1 according to this embodiment includes the ferrule 10 described above and a plurality of optical fibers 20 inserted into the fiber insertion hole 11. In general, a configuration in which a plurality of optical fibers 20 are inserted into one fiber insertion hole 11 requires higher accuracy in positioning the optical fibers 20 compared to a case in which only one optical fiber 20 is inserted into one fiber insertion hole 11. Since the straight portion 11b of the fiber insertion hole 11 has the characteristics described above, positioning accuracy can be maintained even in a configuration in which a plurality of optical fibers 20 are inserted into one fiber insertion hole 11.

Second Embodiment
Next, a second embodiment will be described, but the basic configuration is similar to that of the first embodiment, so the same components are given the same reference numerals and the description thereof will be omitted, and only the differences will be described.

As shown in FIG. 7, the ferrule 2 with optical fiber according to this embodiment has two gate marks 40. That is, the housing H has two gate surfaces S. Hereinafter, the two gate marks 40 are referred to as the first gate mark 41 and the second gate mark 42, respectively. The wall surface 11s2 on which the first gate mark 41 is formed is referred to as the first gate surface S1, and the wall surface 11s2 on which the second gate mark 42 is formed is referred to as the second gate surface S2. In the illustrated example, of the four wall surfaces 11s2 of the flange portion H2, the two wall surfaces 11s2 facing the first direction X correspond to the first gate surface S1 and the second gate surface S2. The second gate surface S2 is located on the opposite side of the first gate surface S1. In this embodiment as well, the filling direction is the first direction X, and the intersecting direction is the second direction Y.

As shown in FIG. 8, the fiber insertion hole 11 according to this embodiment has two arc portions 11a and two straight portions 11b. Each of the two straight portions 11b extends parallel to the first gate surface S1 and the second gate surface S2. Hereinafter, the straight portion 11b closer to the first gate surface S1 of the two straight portions 11b is referred to as the first straight portion 11b1, and the straight portion 11b closer to the second gate surface S2 is referred to as the second straight portion 11b2. The second straight portion 11b2 is located on the opposite side of the first straight portion 11b1 in the first direction X. The two arc portions 11a connect both ends of the first straight portion 11b1 and the second straight portion 11b2 in the second direction Y. One of the two arc portions 11a is referred to as the first arc portion 11a1, and the other is referred to as the second arc portion 11a2. The second arc portion 11a2 is located on the opposite side to the first arc portion 11a1 in the second direction Y.

As described above, the ferrule 2 with optical fiber according to this embodiment further includes a second gate mark 42, which is a mark of a gate 52 that fills a resin into a mold 50 for molding a housing H, formed on the second gate surface S2, which is one of the multiple wall surfaces 11s2 and is located opposite to the first gate surface S1, and the fiber insertion hole 11 further includes a second straight portion 11b2 that is on a straight line and located opposite to the first straight portion 11b1, and a second arc portion 11a2 that is arc-shaped, in a cross section, and the second straight portion 11b2 is parallel to the second gate surface S2. Even in this configuration, the first straight portion 11b1 and the second straight portion 11b2 face in the filling direction (the first direction X in the illustrated example). This makes it possible to suppress unintended deformation of the fiber insertion hole 11 during the molding process of the ferrule 10, compared to the case where the straight portion 11b faces in the intersecting direction (the second direction Y in the illustrated example). This makes it possible to prevent a decrease in the positioning accuracy of the bare fiber 21 within the fiber insertion hole 11.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, the gate surface S faces the first direction X, but the gate surface S may face the second direction Y. In other words, the filling direction may be the second direction Y, and the intersecting direction may be the first direction X. In this case, the straight portion 11b may extend in the first direction X.

In addition, while in the above embodiment the gate surface S was the wall surface 11s2 of the flange portion H2, the gate surface S may be the wall surface 11s1 of the connection portion H1. Note that while the housing H in this embodiment includes the connection portion H1 and the flange portion H2, the shape of the housing H can be modified as appropriate. Regardless of the shape of the housing H, at least one of the multiple wall surfaces (multiple surfaces surrounding the connection end surface 10a) of the housing H can be made the gate surface S, and a straight portion 11b can be provided parallel to the gate surface S, thereby providing the same effect as in the above embodiment.

In addition, the components in the above-described embodiments may be replaced with well-known components as appropriate without departing from the spirit of the present invention, and the above-described embodiments and variations may be combined as appropriate.

1, 2...Ferrule with optical fiber 10...Ferrule (Ferrule for optical fiber) 10a...Connection end face 11...Fiber insertion hole 11a1...First arcuate portion 11a2...Second arcuate portion 11b1...First straight portion 11b2...Second straight portion 11s1, 11s2...Wall surface 20...Optical fiber 41...First gate mark 42...Second gate mark 50...Mold 52...Gate O...Center axis

Claims (4)

a housing molded from resin, the housing having a connection end surface and a plurality of wall surfaces surrounding the connection end surface;
a fiber insertion hole that opens in the connection end surface and through which an optical fiber can be inserted;
a first gate mark, which is a mark of a gate formed on a first gate surface that is one of the plurality of wall surfaces and which is formed by filling the resin into a mold for molding the housing;
the fiber insertion hole has a first linear portion and a first arc portion in a cross section perpendicular to a central axis of the fiber insertion hole,
the first linear portion is parallel to the first gate surface;
Ferrules for optical fibers. the first linear portion is located between the first gate surface and the first arc portion in a direction perpendicular to the first gate surface.
2. The optical fiber ferrule according to claim 1. a second gate mark formed on a second gate surface which is one of the plurality of wall surfaces and is located on the opposite side of the first gate surface, the second gate mark being a mark of a gate where the resin was filled into a metal mold for molding the housing;
the fiber insertion hole further has a second linear portion that is linear and located on an opposite side to the first linear portion in the cross section, and a second arc portion that is arc-shaped,
the second linear portion is parallel to the second gate surface;
3. The optical fiber ferrule according to claim 2. The optical fiber ferrule according to any one of claims 1 to 3,
A plurality of optical fibers are inserted into the fiber insertion holes.
Ferrule with optical fiber.

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