Optical connector, optical connection assembly, and method for manufacturing optical connector

Abstract

An optical connector according to the present disclosure is provided with: an optical connector ferrule including a ferrule end surface and at least one through-hole extending from the ferrule end surface; and at least one optical waveguide member including a tip surface exposed at the ferrule end surface and a plurality of cores exposed at the tip surface, the at least one optical waveguide member being held by the optical connector ferrule in a state of being inserted into the through-hole. The ferrule end face has a shape having a first center line and a second center line. The core is disposed at a position offset from the central axis of the optical waveguide member, and includes at least an outermost core disposed at a position farthest from the central axis. When a parallel first straight line passing through the central axis and along the first center line is drawn on the tip surface, the center of the outermost core is disposed at a position offset from the first straight line.

Description

Technical Field

[0001] This disclosure relates to optical connectors, optical connection assemblies, and methods for manufacturing optical connectors. This application claims priority based on Japanese Application No. 2023-174446, filed on October 6, 2023, and invokes all the contents described in the said Japanese application. Background Technology

[0002] For example, Patent Document 1 discloses an optical connector for connecting multi-core optical fibers to each other. As a method of connecting multi-core optical fibers, the PC (Physical Contact) method is generally known. In the PC method, the fiber end face of the optical connector is physically contacted and pressed against the fiber end face of the optical connector to which it is connected, thereby achieving optical coupling between the optical fibers.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 9-68627 Summary of the Invention

[0004] The optical connector disclosed herein comprises: an optical connector ferrule, including a ferrule end face and at least one through hole extending from the ferrule end face; and at least one optical waveguide member, including a top face exposed on the ferrule end face and a plurality of fiber cores exposed on the top face, the at least one optical waveguide member being held in the optical connector ferrule when inserted into the through hole, the ferrule end face having a shape having a first center line and a second center line having a length shorter than the first center line, the fiber cores being disposed at a position offset from the central axis of the optical waveguide member, the fiber cores including an outermost fiber core disposed at a position furthest from the central axis, wherein, if a first straight line is drawn in the top face that passes through the central axis and is parallel to the first center line, the center of the outermost fiber core is disposed at a position offset from the first straight line. Attached Figure Description

[0005] Figure 1 This is a cross-sectional view showing an optical connection assembly according to one embodiment.

[0006] Figure 2 It means Figure 1 A 3D view of the optical connectors included in the optical connection assembly.

[0007] Figure 3 It means Figure 2 The front view of the optical connector.

[0008] Figure 4 It means Figure 2 A flowchart illustrating an example of the manufacturing process of an optical connector.

[0009] Figure 5AThis is a cross-sectional view used to illustrate the effect of the optical connector.

[0010] Figure 5B This is a cross-sectional view used to illustrate the effect of the optical connector.

[0011] Figure 6 It is Figure 5B An enlarged cross-sectional view of part A.

[0012] Figure 7 This is a front view showing a modified example of an optical connector.

[0013] Figure 8 This is a front view showing the optical connector of a comparative example.

[0014] Figure 9A It is used for explanation Figure 8 A cross-sectional view of the problems with the optical connector.

[0015] Figure 9B It is used for explanation Figure 8 A cross-sectional view of the problems with the optical connector.

[0016] Figure 10 It is Figure 9B The enlarged cross-sectional view of part B. Detailed Implementation

[0017] [The problem this disclosure aims to solve] In manufacturing optical connectors as described above, to connect optical fibers to each other, the ferrule end faces are sometimes polished while the fibers are installed in the ferrule. This polishing process removes damage to the fiber end faces and adjusts the slope of the ferrule end faces. However, during this polishing process, the ferrule end faces and the fiber end faces polished simultaneously can sometimes deviate significantly from their ideal positions due to polishing errors. In this case, when connecting the optical connector to another optical connector, gaps can easily form between the fiber end faces, making direct contact between them difficult. As a result, the connection loss between the optical connectors may increase.

[0018] This disclosure provides an enlarged optical connector, an optical connection assembly, and a method for manufacturing the optical connector, all of which reduce connection loss.

[0019] [Effects of this disclosure] According to the optical connector, optical connection assembly, and manufacturing method of the optical connector disclosed herein, the increase in connection loss can be reduced.

[0020] [Description of embodiments of this disclosure] First, the contents of the embodiments of this disclosure will be described.

[0021] (1) The optical connector of the present disclosure comprises: an optical connector ferrule, including a ferrule end face and at least one through hole extending from the ferrule end face; and at least one optical waveguide member, including a top face exposed on the ferrule end face and a plurality of fiber cores exposed on the top face, the at least one optical waveguide member being held in the optical connector ferrule when inserted into the through hole, the ferrule end face having a shape having a first center line and a second center line having a length shorter than the length of the first center line, the fiber cores being disposed at a position offset from the central axis of the optical waveguide member, the fiber cores including an outermost fiber core disposed at a position furthest from the central axis, and in the case where a first straight line is drawn in the top face that passes through the central axis and is parallel to the first center line, the center of the outermost fiber core being disposed at a position offset from the first straight line.

[0022] When manufacturing optical connectors, during the grinding process of the ferrule end face and the top surface of the optical waveguide component, the machining range along the long dimension of the ferrule end face along the first centerline is larger than the machining range along the short dimension of the ferrule end face along the second centerline. Therefore, there is a tendency for the grinding amount error (grinding error) to be larger at the location along the long dimension of the ferrule end face. When connecting the optical connector to another optical connector, this grinding error may result in large gaps between the ferrule end faces at the location along the long dimension. At locations where large gaps exist, it may be difficult for the fiber cores of the optical waveguide component exposed on the ferrule end face to directly contact the fiber cores of the optical waveguide component exposed on the ferrule end face of the other connector. To facilitate direct contact between these fiber cores, it is effective to avoid placing the fiber cores of the optical waveguide component at the location along the long dimension of the ferrule end face, i.e., at the location susceptible to the effect of grinding error. The outermost fiber core, located furthest from the central axis of the optical waveguide component, is susceptible to grinding errors, causing it to deviate significantly from its ideal position. Therefore, it is important to avoid positioning the outermost fiber core along the longitudinal direction of the ferrule end face. Thus, in the aforementioned optical connector, when viewing the ferrule end face axially, i.e., when drawing a first straight line through the central axis of the optical waveguide component and parallel to the first center line on the top surface, the center of the outermost fiber core of the optical waveguide component is positioned off-center from this first straight line. In other words, it is configured such that the outermost fiber core is not positioned along the longitudinal direction of the ferrule end face. This reduces the likelihood of direct contact between the fiber cores when connecting the optical connector to another optical connector, even in the event of grinding errors. Consequently, it reduces the likelihood of increased connection loss between optical connectors.

[0023] (2) Alternatively, the optical connector described in (1) above may have a plurality of optical waveguide members with their top surfaces arranged along a first straight line, and the optical connector ferrule may include a plurality of through holes for inserting the plurality of optical waveguide members. In the case where the plurality of optical waveguide members are arranged along the first straight line in this manner, the fiber cores of the optical waveguide members are easily positioned on the first straight line, which is susceptible to the influence of grinding and processing errors. In contrast, in the optical connector described above, as mentioned above, the outermost fiber cores of the optical waveguide members are positioned off-line, thus effectively achieving the aforementioned effect.

[0024] (3) In the optical connector described in (1) or (2) above, the optical waveguide component may also be a multi-core optical fiber comprising multiple cores. In this case, the cores of the optical waveguide component are easily positioned on a first straight line that is susceptible to the effects of grinding and polishing errors. In contrast, in the optical connector described above, as mentioned above, the outermost core of the optical waveguide component is positioned off-line, thus effectively achieving the aforementioned effect.

[0025] (4) In the optical connector described in (3) above, the centers of all the fiber cores of the optical waveguide member may be positioned off-center from the first straight line on the top surface. In this case, all the fiber cores, including the outermost fiber core, can be positioned off-center from the first straight line, which is susceptible to grinding errors. Thus, even in the event of grinding errors, the difficulty in making direct contact between the fiber cores when connecting the optical connector to another optical connector can be reduced more effectively. As a result, the increase in connection loss between optical connectors can be reduced more effectively.

[0026] (5) In the optical connector described in (4) above, all the fiber cores of the optical waveguide member may be symmetrically arranged about the central axis in the top surface. Assuming that the fiber cores of the optical waveguide member are asymmetrically arranged about the central axis, it can be assumed that when the rotational position of the optical waveguide member is adjusted with the outermost fiber core positioned off-center from the first straight line, the other fiber core opposite the outermost fiber core will be extremely close to the first straight line, which is susceptible to grinding errors. In contrast, in the configuration described in (5) above, the situation where the other fiber core opposite the outermost fiber core is extremely close to the first straight line when the rotational position of the optical waveguide member is adjusted can be reduced. Therefore, even in the event of grinding errors, the situation where it is difficult to make direct contact between the fiber cores when connecting the optical connector to another optical connector can be reduced more effectively. As a result, the increase in connection loss between optical connectors can be reduced more effectively.

[0027] (6) In any of the optical connectors described in (1) to (5) above, if a second straight line is drawn on the top surface that passes through the central axis and is parallel to the second center line, the center of the outermost fiber core may be positioned closer to the second straight line than the first straight line in the rotational direction centered on the central axis. In this case, the outermost fiber core can be positioned in a position less susceptible to the effects of grinding process errors, thus making it easier for the fiber cores to come into direct contact with each other when the optical connector is connected to the other optical connector. As a result, the increase in connection loss between optical connectors can be reduced more effectively.

[0028] (7) Alternatively, the optical connection assembly of this disclosure may include a first optical connector and a second optical connector as optical connectors as described in any one of (1) to (6) above, wherein the ferrule end face of the first optical connector and the ferrule end face of the second optical connector are opposed in the direction extending along the central axis. Since the optical connection assembly includes a first optical connector and a second optical connector as either of the aforementioned optical connectors, it can effectively achieve the aforementioned effect of reducing the increase in connection loss between optical connectors.

[0029] (8) The method for manufacturing the optical connector disclosed herein includes the following steps: preparing an optical connector ferrule and preparing an optical waveguide component, wherein the optical connector ferrule includes a ferrule end face and at least one through hole extending from the ferrule end face, and the optical waveguide component includes a top face and a plurality of fiber cores exposed on the top face; inserting the optical waveguide component into the through hole with the top face exposed from the ferrule end face; adjusting the rotational position of the optical waveguide component about a central axis while the optical waveguide component is inserted into the through hole; and, after determining the rotational position of the optical waveguide component, adjusting the optical waveguide component's rotational position about a central axis. The ferrule end face and the top face are ground. The ferrule end face has a shape with a first center line and a second center line shorter than the length of the first center line. The fiber core is disposed at a position offset from the central axis of the optical waveguide component. The fiber core includes at least the outermost fiber core disposed at the position farthest from the central axis. In the process of adjusting the rotational position of the optical waveguide component, the rotational position of the optical waveguide component about the central axis is determined as follows: when a first straight line passing through the central axis and parallel to the first center line is drawn in the top face, the center of the outermost fiber core is disposed at a position offset from the first straight line.

[0030] In the aforementioned manufacturing method of the optical connector, when grinding the ferrule end face and the top surface of the optical waveguide component with the rotational position of the optical waveguide component determined, the machining range of the ferrule end face along the long dimension direction of the first centerline is larger than the machining range along the short dimension direction of the ferrule end face. Therefore, there is a tendency for the grinding amount error (grinding error) to increase at the position of the ferrule end face along the long dimension direction. When connecting the optical connector to the optical connector of the other party, such grinding error may cause a large gap between the ferrule end faces at the position of the ferrule end face along the long dimension direction. At the position where a large gap occurs, it may be difficult to make direct contact between the fiber core of the optical waveguide component exposed on the ferrule end face and the fiber core of the optical waveguide component exposed on the ferrule end face of the other party. In order to facilitate direct contact between these fiber cores, it is effective not to place the fiber core of the optical waveguide component at the position of the ferrule end face along the long dimension direction, that is, at the position that is easily affected by the grinding error. The outermost fiber core, located furthest from the central axis of the optical waveguide component, is susceptible to grinding errors, causing it to deviate significantly from its ideal position. Therefore, it is important to avoid positioning the outermost fiber core along the longitudinal direction of the ferrule end face. Thus, in the aforementioned optical connector manufacturing method, when adjusting the rotational position of the optical waveguide component, the rotational position of the optical waveguide component about its central axis is determined such that, when viewing the ferrule end face along the axial direction extending from the central axis (i.e., when a first straight line passing through the central axis and parallel to the first center line is drawn on the top surface), the center of the outermost fiber core is positioned away from this first straight line. In other words, the rotational position of the optical waveguide component is determined so that the outermost fiber core is not positioned along the longitudinal direction of the ferrule end face. This reduces the likelihood of direct contact between the fiber cores when connecting the optical connector to another optical connector, even in the event of grinding errors. Consequently, it reduces the increase in connection loss between optical connectors.

[0031] [Details of the embodiments disclosed herein] The following detailed description, with reference to the accompanying drawings, illustrates specific examples of optical connectors, optical connection assemblies, and methods for manufacturing optical connectors according to this disclosure. The invention is not limited to these examples, but is shown in the claims, which are intended to include all modifications within the meaning and scope equivalent to the claims. In the description of the drawings, the same reference numerals are used to refer to the same elements, and repeated descriptions are omitted.

[0032] Figure 1 This is a cross-sectional view showing the optical connection component 1 of this embodiment. (e.g.) Figure 1As shown, the optical connector assembly 1 includes, for example, an optical connector 2 (first optical connector) and an optical connector 22 (second optical connector) for connection. Optical connectors 2 and 22 have, for example, the same shape. Optical connectors 2 and 22 are positioned opposite each other along axis D1, for example, with optical connector 22 flipped upside down relative to optical connector 2. Axis D1 is the direction in which the central axis C15 of the optical fiber 15 (described later) extends and is the connection direction between optical connectors 2 and 22. Optical connectors 2 and 22 are mated together and connected by a PC along axis D1. Thus, optical coupling between optical connectors 2 and 22 is achieved.

[0033] Figure 2 This is a 3D view of optical connector 2. Figure 3 This is a front view showing optical connector 2. (Example) Figure 2 As shown, the optical connector 2 includes, for example, a ferrule 5 (optical connector ferrule) and multiple optical fibers 15 (optical waveguide components). The ferrule 5 has a generally cuboid shape and is made of, for example, resin. The ferrule 5 is, for example, an MT ferrule. The ferrule 5 includes, for example, a ferrule end face 5a at a first end provided in the axial direction D1 and a rear end face 5b at a second end provided in the axial direction D1. Figure 1 In the optical connection assembly 1, the ferrule end face 5a is opposite to the ferrule end face 5a of the optical connector 22 connected to the other party in the axial direction D1. The ferrule end face 5a can contact the ferrule end face 5a connected to the other party, or it can be separated from the ferrule end face 5a connected to the other party. An inlet 6 for receiving multiple optical fibers 15 is formed on the rear end face 5b (see reference). Figure 1 ).

[0034] like Figure 3 As shown, the ferrule end face 5a, observed along axis D1, has a shape with a major axis (first centerline) A2 and a minor axis (second centerline) A3, for example, when an ellipse internally tangent to the shape of the ferrule end face 5a is defined. The first centerline A2 is a line segment (axis of symmetry) passing through the center of the ferrule end face 5a and along the longitudinal direction D2 of the ferrule end face 5a. The second centerline A3 is a line segment (axis of symmetry) passing through the center of the ferrule end face 5a and along the minor direction D3 of the ferrule end face 5a. The length of the first centerline A2 is longer than the length of the second centerline A3. Therefore, the length of the ferrule end face 5a along the longitudinal direction D2 along the first centerline A2 is longer than the length of the ferrule end face 5a along the minor direction D3 along the second centerline A3. The length of the second centerline A3 is shorter than the length of the first centerline A2. For example, the ferrule end face 5a may be a rectangle that extends long along the longitudinal direction D2. The long side of the ferrule end face 5a extends along the long dimension direction D2, and the short side of the ferrule end face 5a extends along the short dimension direction D3. The long dimension direction D2 and the short dimension direction D3 are directions that intersect (e.g., orthogonal) the axial direction D1. The long dimension direction D2 intersects (e.g., orthogonal) the short dimension direction D3.

[0035] The insert 5 also includes multiple through holes 7 and a pair of guide holes 8. For example... Figure 1 As shown, each optical fiber 15 is inserted into each through-hole 7. Each through-hole 7 is an optical fiber holding hole that holds the inserted optical fiber 15. Multiple through-holes 7 extend from the ferrule end face 5a toward the inlet 6 along the axial direction D1. The front end of each through-hole 7 opens at the ferrule end face 5a. The direction in which the central axis of each through-hole 7 extends is consistent with the axial direction D1. The openings of each through-hole 7 are arranged in a row along the longitudinal direction D2 at the ferrule end face 5a.

[0036] like Figure 2 As shown, guide holes 8 are arranged along the longitudinal direction D2, formed at a pair of positions separated by multiple through holes 7 (in other words, at both ends of a row of through holes 7). The guide holes 8 pass through the insert 5 in the axial direction D1. A pair of guide pins are inserted into the guide holes 8. With the pair of guide pins inserted into the guide holes 8, they are inserted into the optical connector 22 that connects to the other (see reference). Figure 1 A pair of guide holes. Thus, the relative position of the optical connector 2 and the optical connector 22 connected to it is fixed.

[0037] Multiple optical fibers 15 extend along the axial direction D1 and are arranged along the longitudinal direction D2, corresponding to the through holes 7 of the ferrule 5, respectively. In one example, twelve optical fibers 15 are arranged in a row along the longitudinal direction D2. Each optical fiber 15 is inserted into the through hole 7 along the axial direction D1. The configuration and number of the multiple optical fibers 15 can be appropriately varied according to the required specifications. For example, the optical fiber row formed by twelve optical fibers 15 arranged in the longitudinal direction D2 can also be configured into two rows along the short direction D3. The number of optical fibers 15 is not limited to twelve and can also be other numbers.

[0038] Each optical fiber 15 is covered by a resin-made outer sheath 12 to form an optical fiber core 13. The outer sheath 12 is removed from the optical fiber core 13 from the middle to the tip along the axial direction D1, thereby exposing the optical fiber 15. Each optical fiber 15 is fixed to the ferrule 5 by adhesive injected into the ferrule 5 while being inserted into the through holes 7. With each optical fiber 15 inserted into the through holes 7, the optical fiber end face 15a (top face) of each optical fiber 15 is exposed through the opening of the through hole 7 formed on the end face 5a of the ferrule.

[0039] With each optical fiber 15 inserted into each through hole 7 of the ferrule 5, an inclined grinding process is performed on the ferrule end face 5a, for example. In the inclined grinding process, the ferrule end face 5a is ground in a manner that it is inclined (e.g., 8 degrees) relative to the surface perpendicular to the axial direction D1. As a result, the ferrule end face 5a is inclined relative to the surface perpendicular to the axial direction D1. Figure 1As shown, the ferrule end face 5a is inclined in a direction perpendicular to the central axis C15 in the section containing the central axis C15. More specifically, the ferrule end face 5a extends in a direction inclined relative to the short dimension direction D3 perpendicular to the axial direction D1 in the section passing through the central axis C15 and along the minor dimension direction D3 and the axial direction D1.

[0040] Correspondingly, the fiber end face 15a of each optical fiber 15, which is polished simultaneously with the ferrule end face 5a, is also inclined relative to the surface perpendicular to the axial direction D1, just like the ferrule end face 5a. That is, each fiber end face 15a extends in a manner inclined relative to the short dimension direction D3 perpendicular to the axial direction D1 in the cross section passing through the central axis C15 and along the minor dimension direction D3 and the axial direction D1. Each fiber end face 15a may, for example, protrude relative to the ferrule end face 5a in the axial direction D1, or it may be a surface flush with the ferrule end face 5a without any height difference.

[0041] Sometimes, the ferrule end face 5a is also subjected to right-angle grinding with each optical fiber 15 inserted into each through hole 7 of the ferrule 5. In the right-angle grinding process, the ferrule end face 5a is ground so that it is perpendicular to the axis D1. As a result, the ferrule end face 5a and each optical fiber end face 15a are together perpendicular to the axis D1.

[0042] like Figure 3 As shown, each optical fiber 15 is, for example, a multi-core optical fiber comprising two (or more) cores 16A and 16B and a cladding 17 surrounding the cores 16A and 16B. Cores 16A and 16B have a refractive index higher than that of the cladding. Cores 16A and 16B are exposed at the fiber end face 15a and are arranged adjacent to each other at the fiber end face 15a. The number of cores in the optical fiber 15 is not limited to two; for example, it can also be four, six, or eight or more.

[0043] Fiber cores 16A and 16B, for example, when viewed along the optical fiber end face 15a along the axial direction D1, are positioned off-center from the central axis C15 of the optical fiber 15. Fiber cores 16A and 16B are, for example, positioned at a pair of locations on the optical fiber end face 15a, separated by the central axis C15. The distance between the central axis C15 and the center C16A of fiber core 16A is equal to the distance between the central axis C15 and the center C16B of fiber core 16B. Therefore, fiber cores 16A and 16B are symmetrically arranged about the central axis C15. Alternatively, it can be said that fiber cores 16A and 16B are symmetrically arranged about a point on the central axis C15.

[0044] At least one of fiber cores 16A and 16B corresponds to the "outermost fiber core" farthest from the central axis C15. The "outermost fiber core" farthest from the central axis C15 refers to the fiber core of fiber cores 16A and 16B located furthest from the central axis C15 when viewed along the fiber end face 15a along the axial direction D1. In the case where the two fiber cores 16A and 16B are symmetrically arranged about the central axis C15 as in this embodiment, the fiber cores 16A and 16B are arranged at equal distances relative to the central axis C15. In this case, either fiber core 16A or 16B can also be defined as the "outermost fiber core". In this embodiment, for convenience, fiber core 16A is defined as the "outermost fiber core". Hereinafter, "fiber core 16A" will be replaced with "outermost fiber core 16A" as needed for explanation.

[0045] From the viewpoint of clarifying the correspondence between the two fiber cores 16A and 16B and the two fiber cores 16A and 16B of the optical connector 22 connecting them, the first fiber core of the two fiber cores 16A and 16B is sometimes configured to deliberately deviate from its symmetrical position relative to the second fiber core. As a result, the first fiber core is sometimes configured to be further away from the central axis C15 than the second fiber core. In this case, only the first fiber core is equivalent to the "outermost fiber core". For example, when fiber core 16B is configured to be further away from the central axis C15 than fiber core 16A, fiber core 16B is equivalent to the "outermost fiber core".

[0046] In this embodiment, such as Figure 3 As shown, when observing the ferrule end face 5a along axis D1, i.e., when drawing a first straight line L2 that passes through the central axis C15 and is parallel to the longitudinal direction D2 in the fiber end face 15a, the center C16A of the outermost fiber core 16A is positioned offset from the first straight line L2. This offset means that when observing the ferrule end face 5a along axis D1, the center C16A of the outermost fiber core 16A does not coincide with the first straight line L2, but is positioned separately from it. Therefore, when drawing a straight line L16A connecting the central axis C15 and the center C16A of the outermost fiber core 16A along axis D1 on the ferrule end face 5a, the dashed line L16A does not coincide with the first straight line L2, but intersects it. That is to say, when the direction of extension of straight line L16A is set as the outermost core direction D16A, the outermost core direction D16A is not parallel to the long dimension direction D2, but intersects the long dimension direction D2.

[0047] When observing the ferrule end face 5a along axis D1, i.e., when drawing a second straight line L3 in the fiber end face 15a that passes through the central axis C15 and is parallel to the short dimension direction D3, the center C16A of the outermost fiber core 16A is positioned closer to the second straight line L3 relative to the first straight line L2 in the rotation direction D4 centered on the central axis C15. In other words, when the angle of the straight line L16A about the central axis C15 with reference to the first straight line L2 is set as the rotation angle θ, the rotation angle θ is, for example, set to a range greater than 45 degrees and less than or equal to 90 degrees. Figure 3 In the example shown, the center C16A of the outermost core 16A is positioned on the second straight line L3. In this case, the straight line L16A connecting the central axis C15 and the center C16A of the outermost core 16A is aligned with the second straight line L3 and perpendicular to the first straight line L2. That is, the rotation angle θ of the straight line L16A is 90 degrees. The outermost core direction D16A along the straight line L16A is perpendicular to the long dimension direction D2 and parallel to the short dimension direction D3.

[0048] In this embodiment, when observing the ferrule end face 5a along axis D1, that is, within the fiber end face 15a, the centers C16A and C16B of all fiber cores 16A and 16B, including the outermost fiber core 16A, are positioned offset from the first straight line L2. Therefore, when drawing the straight line L16B ​​connecting the central axis C15 and the center C16B of the fiber core 16B while observing the ferrule end face 5a along axis D1, the straight line L16B, like the straight line L16A, does not coincide with the first straight line L2, but rather intersects the first straight line L2. Specifically, the straight line L16B, like the straight line L16A, coincides with the second straight line L3 and is perpendicular to the first straight line L2.

[0049] Next, refer to Figure 4 The manufacturing method of the optical connector 2 described above will be explained. Figure 4 This is a flowchart illustrating the manufacturing process of optical connector 2.

[0050] First, such as Figure 4 As shown, a ferrule 5 and a plurality of optical fibers 15 are prepared (step S11). The ferrule 5 includes, for example, a plurality of through holes 7 extending from the ferrule end face 5a along the axial direction D1 and arranged along the longitudinal direction D2. Each optical fiber 15 includes, for example, two fiber cores 16A and two fiber cores 16B. The two fiber cores 16A and two fiber cores 16B are arranged symmetrically about the central axis C15. Here, for convenience, "fiber core 16A" is defined as the "outermost fiber core 16A" that is farthest from the central axis C15.

[0051] Next, each optical fiber 15 is inserted into the ferrule 5 (step S12). For example, each optical fiber 15 is inserted into the through hole 7 of the ferrule 5 along the axial direction D1, so that the fiber end face 15a of each optical fiber 15 is exposed above the ferrule end face 5a. Each fiber end face 15a protrudes slightly along the axial direction D1 relative to the ferrule end face 5a, for example.

[0052] Next, the rotational position of each fiber 15 relative to the ferrule 5 is adjusted (step S13). At this time, the rotational position of each fiber 15 about the central axis C15 is determined as follows: when observing the ferrule end face 5a along the axial direction D1, a first straight line L2 is drawn that passes through the central axis C15 of the fiber 15 and is parallel to the first center line A2 of the ferrule end face 5a; the center C16A of the outermost fiber core 16A is positioned offset from the first straight line L2. As a result, when observing the ferrule end face 5a along the axial direction D1, i.e., when drawing a second straight line L3 in the fiber end face 15a that passes through the central axis C15 of the fiber 15 and is parallel to the second center line A3 of the ferrule end face 5a, the center C16A of the outermost fiber core 16A is positioned on the second straight line L3, opposite to the outermost fiber core 16A across the central axis C15.

[0053] Next, the position of each optical fiber 15 relative to the ferrule 5 is fixed (step S14). For example, with the rotational position of each optical fiber 15 relative to the ferrule 5 determined, adhesive is introduced into the interior of the ferrule 5. As the adhesive, for example, an adhesive with a high viscosity that will not flow out from the through holes 7 inside the ferrule 5 to the ferrule end face 5a can be used. The adhesive cures inside the ferrule 5, thereby fixing each optical fiber 15 to the ferrule 5.

[0054] Next, the ferrule end face 5a and each fiber end face 15a are ground (step S15). For example, with the rotational position of each fiber 15 relative to the ferrule 5 determined, the ferrule end face 5a and each fiber end face 15a exposed on the ferrule end face 5a are subjected to inclined grinding. As a result, the ferrule end face 5a and each fiber end face 15a are inclined relative to a surface perpendicular to the axis D1. For example, as... Figure 1 As shown, the ferrule end face 5a and each fiber end face 15a are inclined relative to the short dimension direction D3 in the cross section along the short dimension direction D3 and the axial direction D1. Alternatively, the ferrule end face 5a and each fiber end face 15a can be ground at right angles. After the above processes, the optical connector 2 is obtained.

[0055] The effects obtained by the optical connector 2, optical connection assembly 1, and manufacturing method of the optical connector 2 of this embodiment will be explained together with the problems of the comparative examples.

[0056] Figure 8This is a front view of the optical connector 200, which is a comparative example. Figure 9A and Figure 9B This is a cross-sectional view used to illustrate the problems of the optical connector 200. Figure 10 This is a cross-sectional view showing part B of Figure 9(b) in an enlarged form. For example... Figure 8 As shown, in the optical connector 200, the centers C116A and C116B of each fiber core 116A and fiber core 116B held in the ferrule 5 are arranged on the first straight line L2. That is, the straight line L116A connecting the central axis C115 and the center C116A of fiber core 116A, and the straight line L116B connecting the central axis C115 and the center C116B of fiber core 116B, are parallel to the longitudinal direction D2 and coincide with the first straight line L2.

[0057] Figure 9A and Figure 9B The diagram illustrates the connection of optical connector 200 to optical connector 220. The grinding process performed on the ferrule end face 5a results in the ferrule end face 5a and each fiber end face 115a sometimes deviating significantly from the ideal state. For example, when the ferrule end face 5a is ground at an angle relative to the shorter dimension direction D3, ideally, the ferrule end face 5a should not be angled relative to the longer dimension direction D2, but rather parallel to D2. That is, in the cross-section along the longer dimension direction D2 and the axial direction D1 (refer to...) Figure 9A On the ), the ideal state is when the end face 5a of the ferrule is along the ideal straight line VL along the length direction D2.

[0058] In the grinding process, the machining range along the long dimension D2 of the ferrule end face 5a is larger than the machining range along the short dimension D3. Therefore, due to grinding errors, the ferrule end face 5a is prone to deviate significantly from its ideal state at a position along the long dimension D2. In other words, Figure 9A As shown, in the cross-section along the longitudinal direction D2 and the axial direction D1, the ferrule end face 5a tends to deviate from the ideal straight line VL along the longitudinal direction D2, instead tilting towards it. Consequently, the closer to the end of the ferrule end face 5a along the longitudinal direction D2, the greater the positional deviation of the ferrule end face 5a relative to the ideal straight line VL. This results in a greater positional deviation in the fiber end faces 115a of each fiber 115 that are simultaneously ground with the ferrule end face 5a. Such positional deviation also occurs when the ferrule end face 5a is ground at right angles.

[0059] When optical connectors 200 and 220, which have ferrule end faces 5a and fiber end faces 115a that are significantly tilted in the longitudinal direction D2 due to grinding errors, are connected to each other, the closer to the end of the ferrule end face 5a in the longitudinal direction D2, the greater the distance between opposing ferrule end faces 5a, i.e., the distance between opposing fiber end faces 115a. In this case, such as Figure 9B As shown, when optical connectors 200 and 220 are PC connected to each other, large gaps may occur between the fiber end faces 115a and 115a. If such gaps occur, then... Figure 10 As shown, even if you press the optical connector 200 to connect its PC to the optical connector 220 that is connected to the other, it may be difficult to make the fiber end face 115a and the fiber end face 115a fully contact each other.

[0060] As a result, regions that easily contact the fiber end face 115a connected to the other fiber end face 115a and regions that are difficult to contact the other fiber end face 115a are created on the fiber end face 115a. Regions that are difficult to contact the other fiber end face 115a are more likely to occur on the first straight line L2 and at positions far from the central axis C115. Therefore, when the fiber core 116A is defined as the outermost fiber core 116A farthest from the central axis C115, and the outermost fiber core 116A is positioned on the first straight line L2, the outermost fiber core 116A is more likely to be positioned in a region where it is difficult to contact the other fiber end face 115a connected to the other, and thus will be positioned at a position where it is difficult to contact the other fiber end face 115a connected to the other.

[0061] Therefore, even when pressing the optical connector 200 to connect its PC to the optical connector 220, it is sometimes impossible to make the outermost fiber core 116A contact with the outermost fiber core 116A of the fiber end face 115a connected to the other, resulting in gaps between the outermost fiber cores 116A. If such gaps occur, the connection loss between the optical connectors 200 and 220 may increase. If the optical connectors 200 and 220 are pressed together to fill the gaps between the fiber cores 116A, the fiber 115 itself may deform significantly, making it difficult to achieve PC connection between the optical connectors 200 and 220.

[0062] Figure 5A and Figure 5B This is a cross-sectional view used to illustrate the effect of the optical connector 2 in this embodiment. Figure 6 It is Figure 5BA cross-sectional view showing an enlarged view of part A. In the optical connector 2 of this embodiment, the outermost fiber core 16A of the fiber core 16A and fiber core 16B of the optical fiber 15, which is located furthest from the central axis C15, is located at a position offset from the first straight line L2 (see reference). Figure 3 In this case, even if the ferrule end face 5a deviates from the ideal straight line VL along the longitudinal direction D2 due to grinding errors, it can reduce the possibility of the outermost fiber core 16A being positioned in an area where it is difficult to contact the fiber end face 15a to which it is connected. That is to say, as Figure 6 As shown, the outermost fiber core 16A can be positioned in a region close to the central axis C15 of the fiber 15, where it is easy to contact the fiber end face 15a to which it is connected, rather than in a region close to the outer periphery of the fiber 15, where it is difficult to contact the fiber end face 15a to which it is connected. As a result, even if large gaps are created between the fiber end faces 15a due to polishing errors, the difficulty in making direct contact between the outermost fiber cores 16A and 16A can be reduced. Consequently, the increase in connection loss between optical connector 2 and optical connector 22 can be reduced.

[0063] As in this embodiment, the optical connector 2 may also include a plurality of optical fibers 15 arranged along a first straight line L2, and the ferrule 5 may include a plurality of through holes 7 for inserting the plurality of optical fibers 15. In the case where the plurality of optical fibers 15 are arranged along the first straight line L2, the fiber cores 16A and 16B of the optical fibers 15 are easily positioned on the first straight line L2, which is susceptible to the effects of polishing processes. In contrast, in this embodiment, as described above, the fiber cores 16A and 16B of the optical fibers 15 are positioned offset from the first straight line L2, thus effectively achieving the aforementioned benefits.

[0064] As in this embodiment, the optical fiber 15 can also be a multi-core optical fiber including cores 16A and 16B. In this case, cores 16A and 16B of the optical fiber 15 are easily positioned on the first straight line L2, which is susceptible to the influence of polishing errors. In contrast, in this embodiment, as described above, cores 16A and 16B of the optical fiber 15 are positioned off-center from the first straight line L2, thus effectively achieving the aforementioned effects.

[0065] As in this embodiment, when viewing the ferrule end face 5a along axis D1, i.e., in the fiber end face 15a, the centers C16A and C16B of all fiber cores 16A and 16B, including the outermost fiber core 16A, are positioned offset from the first straight line L2. In this case, all fiber cores 16A and 16B can be positioned offset from the first straight line L2, which is easily affected by polishing errors. Therefore, even if polishing errors occur, the difficulty in achieving direct contact between the fiber cores when connecting the optical connector 2 to the optical connector 22 can be more effectively reduced. As a result, the increase in connection loss between the optical connector 2 and the optical connector 22 can be more effectively reduced.

[0066] As in this embodiment, when observing the ferrule end face 5a along axis D1, i.e., in the fiber end face 15a, all the fiber cores 16A and 16B of the fiber 15, including the outermost fiber core 16A, are symmetrically arranged about the central axis C15. Assuming that the fiber cores 16A and 16B of the fiber 15 are asymmetrically arranged about the central axis C15, it can be assumed that when the rotational position of the fiber 15 is adjusted with the outermost fiber core 16A positioned away from the first straight line L2, the fiber core 16B opposite to the outermost fiber core 16A will be extremely close to the first straight line L2, which is easily affected by polishing errors. In contrast, with the fiber cores 16A and 16B symmetrically arranged about the central axis C15 as in this embodiment, the situation where the fiber core 16B opposite to the outermost fiber core 16A is extremely close to the first straight line L2 when the rotational position of the fiber 15 is adjusted can be reduced. Therefore, even with grinding errors, the difficulty in ensuring direct contact between the fiber cores when connecting optical connector 2 to optical connector 22 can be reduced more effectively. Consequently, the increase in connection loss between optical connector 2 and optical connector 22 can be reduced more effectively.

[0067] As in this embodiment, when viewing the ferrule end face 5a along the axial direction D1, i.e., when drawing a second straight line L3 in the fiber end face 15a that passes through the central axis C15 and is parallel to the short dimension direction D3, the center C16A of the outermost fiber core 16A is positioned closer to the second straight line L3 relative to the first straight line L2 in the rotational direction D4 centered on the central axis C15. In this case, the outermost fiber core 16A can be positioned in a position less affected by grinding errors, thus facilitating direct contact between the fiber cores when connecting the optical connector 2 to the optical connector 22. As a result, the increase in connection loss between the optical connector 2 and the optical connector 22 can be reduced more effectively.

[0068] The optical connector, optical connection assembly, and method for manufacturing the optical connector disclosed herein are not limited to the embodiments described above, and various other modifications are also possible.

[0069] Figure 7 This is a front view showing a modified example of the optical connector 2A. (Example:) Figure 7 As shown, the optical connector 2A includes an optical fiber 15A with four cores 18A, 18B, 18C, and 18D. Cores 18A, 18B, 18C, and 18D are, for example, positioned offset from the central axis C15 of the optical fiber 15A and arranged symmetrically about the central axis C15. Cores 18A, 18B, 18C, and 18D are positioned equidistant from the central axis C15 in the optical fiber end face 15a. Therefore, any one of cores 18A, 18B, 18C, and 18D can be defined as the "outermost core" farthest from the central axis C15. For convenience, one of the four fiber cores 18A, 18B, 18C, and 18D, fiber core 18A, is defined as the "outermost fiber core". In the following explanation, "fiber core 18A" will be replaced with "outermost fiber core 18A" as needed.

[0070] From the viewpoint of clarifying the correspondence between the four fiber cores 18A, 18B, 18C, and 18D and the four fiber cores of the optical connector connecting them, the first fiber core among the four fiber cores 18A, 18B, 18C, and 18D can be configured to deliberately deviate from its symmetrical position relative to the second to fourth fiber cores. In this case, the first fiber core is equivalent to the "outermost fiber core" configured at a position further away from the central axis C15 than the second to fourth fiber cores.

[0071] like Figure 7 As shown, when observing the ferrule end face 5a along axis D1, i.e., in the fiber end face 15a, the center C18A of the outermost core 18A is positioned offset from the first straight line L2. Therefore, when drawing the straight line L18A connecting the center C18A of the outermost core 18A and the central axis C15 when observing the ferrule end face 5a along axis D1, the straight line L18A, represented by the dashed line, is not consistent with the first straight line L2, but intersects the first straight line L2. That is to say, when the direction of extension of the straight line L18A is set as the outermost core direction D18A, the outermost core direction D18A is not parallel to the long dimension direction D2, but intersects the long dimension direction D2.

[0072] When observing the ferrule end face 5a along axis D1, i.e., when drawing a second straight line L3 in the fiber end face 15a that passes through the central axis C15 and is parallel to the short dimension direction D3, the center C18A of the outermost fiber core 18A is, for example, positioned between the first straight line L2 and the second straight line L3 in the rotation direction D4 centered on the central axis C15. When the angle of the straight line L18A about the central axis C15 with reference to the first straight line L2 is set as the rotation angle θ, the rotation angle θ is, for example, 45 degrees. In this way, the straight line L18A is not parallel to the first straight line L2, but is inclined, for example, relative to both the first straight line L2 and the second straight line L3.

[0073] In optical connector 2A, when viewing the ferrule end face 5a along axis D1, i.e., in the fiber end face 15a, the centers C18A, C18B, C18C, and C18D of all fiber cores 18A, 18B, 18C, and 18D, including the outermost fiber core 18A, are positioned offset from the first straight line L2. That is, the straight line L18B connecting the central axis C15 to the center C18B of fiber core 18B, the straight line L18C connecting the central axis C15 to the center C18C of fiber core 18C, and the straight line L18D connecting the central axis C15 to the center C18D of fiber core 18D, like the straight line L18A, are not aligned with the first straight line L2, but rather intersect with it. Therefore, the straight lines L18B, L18C, and L18D are not parallel to the first straight line L2, but are inclined, for example, relative to both the first straight line L2 and the second straight line L3.

[0074] In optical connector 2A, compared to the case where the outermost fiber core 18A is positioned on the first straight line L2, the outermost fiber core 18A can be positioned in a region close to the central axis C15 of the fiber 15, making it easier to contact the fiber end face 15a connected to it. As a result, even if large gaps are created between the fiber end faces 15a due to polishing errors, the difficulty in making direct contact between the outermost fiber cores 18A is reduced. Consequently, the increase in connection loss between optical connector 2 and optical connector 22 is reduced.

[0075] In the above embodiments, the case where the centers of all the fiber cores of the optical fiber are arranged off-center from the first straight line has been described. However, the centers of the fiber cores arranged closer to the central axis than the outermost fiber core can also be arranged on the first straight line. In the above embodiments, the case where each fiber core of the optical fiber is arranged symmetrically or point-symmetrically about the central axis has been described. However, the fiber cores of the optical fiber can also be arranged non-linearly or non-point-symmetrically about the central axis. Furthermore, the optical fiber may have a central fiber core arranged on the central axis in addition to the peripheral fiber cores arranged off-center from the central axis. In the above embodiments, a "multi-core optical fiber" (fiber 15) is shown as an example of an "optical waveguide member". However, a "bundled optical fiber" composed of multiple single-core optical fibers can also be used as an "optical waveguide member" instead of a multi-core optical fiber. In the above embodiments, the case where the optical waveguide member has multiple fiber cores has been described. However, the optical waveguide member may also have only one fiber core. If one fiber core is set as the outermost fiber core, the same effect as the case where the optical waveguide member has multiple fiber cores can be obtained.

[0076] As is understood from the description of the above embodiments, the following schemes are disclosed in this specification.

[0077] (Note 1) An optical connector includes: an optical connector ferrule, including a ferrule end face and at least one through hole extending from the ferrule end face; and at least one optical waveguide member, including a top face exposed from the ferrule end face and at least one fiber core exposed from the top face, the at least one optical waveguide member being held in the optical connector ferrule when inserted into the through hole, the ferrule end face having a shape having a major axis and a minor axis, the fiber core being disposed at a position offset from the central axis of the optical waveguide member, the fiber core including an outermost fiber core disposed at a position furthest from the central axis, and with a major axis drawn in the top face passing through the central axis and along the major axis, the center of the outermost fiber core being disposed at a position offset from the major axis.

[0078] Explanation of reference numerals in the attached figures 1: Optical connector assembly; 2, 2A: Optical connector (first optical connector); 5: Flanger (optical connector ferrule); 5a: Flanger end face; 5b: Rear end face; 6: Inlet; 7: Through hole; 8: Guide hole; 12: Outer sheath; 13: Fiber optic core; 15, 15A: Fiber optic (optical waveguide component); 15a: Fiber optic end face (top face); 16A, 16B, 18A, 18B, 18C, 18D: Fiber core; 17: Cladding; 22: Optical connector (second optical connector); 115: Fiber optic; 115a: Fiber optic end face; 116A, 116B: Fiber core; 200, 220: Optical connector; A2 A1: First centerline (major axis); A3: Second centerline (minor axis); C15: Central axis; C16A, C16B, C18A, C18B, C18C, C18D, C116A, C116B: Center; D1: Axial axis; D2: Long dimension direction; D3: Short dimension direction; D4: Rotation direction; D16A, D18A: Outermost core direction; L2: First straight line (major axis); L3: Second straight line (minor axis); L16A, L16B, L18A, L18B, L18C, L18D, L116A, L116B: Straight line; VL: Ideal straight line; θ: Rotation angle.

Claims

1. An optical connector, comprising: An optical connector ferrule, including a ferrule end face and at least one through hole extending from said ferrule end face; and At least one optical waveguide component includes a top surface exposed on the end face of the ferrule and a plurality of fiber cores exposed on the top surface, the at least one optical waveguide component being held in the optical connector ferrule when inserted into the through hole. The ferrule end face has a shape having a first center line and a second center line whose length is shorter than the length of the first center line. The fiber core is positioned off-center from the central axis of the optical waveguide component. The fiber core includes the outermost fiber core located at the position furthest from the central axis. When a first straight line is drawn in the top surface that passes through the central axis and is parallel to the first center line, the center of the outermost core is positioned off-center from the first straight line.

2. The optical connector according to claim 1, wherein, The optical connector includes a plurality of optical waveguide components arranged along the first straight line on the top surface. The optical connector ferrule includes a plurality of through holes into which the plurality of optical waveguide components are inserted.

3. The optical connector according to claim 1 or 2, wherein, The optical waveguide component is a multi-core optical fiber comprising multiple fiber cores.

4. The optical connector according to claim 3, wherein, In the top surface, the centers of all the fiber cores of the optical waveguide member are positioned off-center from the first straight line.

5. The optical connector according to claim 4, wherein, In the top surface, all the fiber cores of the optical waveguide member are arranged symmetrically about the central axis point.

6. The optical connector according to any one of claims 1 to 5, wherein, When a second straight line is drawn in the top surface that passes through the central axis and is parallel to the second center line, the center of the outermost core is positioned closer to the second straight line than the first straight line in the rotational direction centered on the central axis.

7. An optical connection component, It comprises a first optical connector and a second optical connector as optical connectors as described in any one of claims 1 to 6. The ferrule end face of the first optical connector is opposite to the ferrule end face of the second optical connector in the direction extending from the central axis.

8. A method for manufacturing an optical connector, comprising the following steps: Prepare the optical connector ferrule and the optical waveguide components, wherein... The optical connector ferrule includes a ferrule end face and at least one through hole extending from the ferrule end face, and the optical waveguide component includes a top face and a plurality of fiber cores exposed on the top face. The optical waveguide component is inserted into the through hole with its top surface exposed on the end face of the ferrule. With the optical waveguide component inserted into the through hole, the rotational position of the optical waveguide component about its central axis is adjusted. as well as With the rotational position of the optical waveguide component determined, the ferrule end face and the top face are ground. The ferrule end face has a shape having a first center line and a second center line whose length is shorter than the length of the first center line. The fiber core is positioned off-axis. The fiber core includes the outermost fiber core located at the position furthest from the central axis. In the process of adjusting the rotational position of the optical waveguide component, The rotational position of the optical waveguide component about the central axis is determined as follows: when a first straight line is drawn in the top surface that passes through the central axis and is parallel to the first center line, the center of the outermost fiber core is positioned off-center from the first straight line.

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