Ferrule and optical connector

Abstract

To provide a ferrule and an optical connector capable of preventing deterioration of optical characteristics.SOLUTION: The ferrule includes a front end surface, a rear end surface located on a side opposite to the front end surface in a first direction, and a plurality of fiber holes opening in the front end surface and arranged in a second direction intersecting the first direction. Each of the plurality of fiber holes has a first hole portion and a second hole portion located closer to the rear end surface than the first hole portion in the first direction. A pitch of the plurality of first holes in the second direction is larger than a pitch of the plurality of second holes in the second direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a ferrule and an optical connector. [Background technology]

[0002] An optical connector is known that includes a plurality of optical fibers and a ferrule that holds the ends of the plurality of optical fibers (see, for example, Patent Document 1). The ferrule has a plurality of fiber holes formed in a row in a predetermined direction, and the plurality of optical fibers are inserted into the corresponding fiber holes. Such a ferrule is manufactured by placing a plurality of core pins, each having a shape corresponding to the fiber holes, in a mold and filling the mold with ferrule material (for example, molten resin). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-119622 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, optical fibers (thin-diameter fibers) with coating diameters smaller than the outer diameter (coating diameter) of conventional optical fibers have been developed. Because the coating layer of thin-diameter fibers is thinner than that of conventional optical fibers, optical fibers can be arranged at a smaller pitch. However, as the pitch of optical fibers becomes smaller, the pitch of fiber holes formed in ferrules and the pitch of core pins used to form the fiber holes during ferrule manufacturing also become smaller. This can lead to the risk that the ferrule material filled in the mold during ferrule manufacturing will not be properly filled between the core pins, and the fiber holes into which the optical fibers are inserted will not be formed in the desired position and shape. This can increase loss when connecting an optical connector to a mating optical connector, potentially degrading optical characteristics.

[0005] An object of the present disclosure is to provide a ferrule and an optical connector that can prevent degradation of optical characteristics. [Means for solving the problem]

[0006] A ferrule according to an embodiment of the present disclosure includes a front end face, a rear end face located on the opposite side of the front end face in a first direction, and a plurality of fiber holes that open at the front end face and are aligned in a second direction intersecting the first direction. Each of the plurality of fiber holes has a first hole portion and a second hole portion located closer to the rear end face in the first direction than the first hole portion. The pitch in the second direction of the plurality of first hole portions, each of which is a first hole portion, is greater than the pitch in the second direction of the plurality of second hole portions, each of which is a second hole portion. [Effects of the Invention]

[0007] According to the present disclosure, a ferrule and an optical connector capable of preventing degradation of optical characteristics are provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an optical connector according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the optical fiber shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the ferrule taken along line III-III shown in FIG. [Figure 4] FIG. 4 is a view showing the front end face of the ferrule shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view of a ferrule showing the configuration of a plurality of second hole portions. [Figure 6] FIG. 6 is a diagram showing an optical connector according to the second embodiment. [Figure 7] FIG. 7 is a cross-sectional view of the ferrule taken along line VII-VII shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view of the ferrule taken along line VIII-VIII shown in FIG. [Figure 9] FIG. 9 is a cross-sectional view showing a modification of the ferrule according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. (1) The ferrule of the present disclosure comprises a front end face, a rear end face located on the opposite side of the front end face in a first direction, and a plurality of fiber holes that open at the front end face and are aligned in a second direction that intersects the first direction, each of the plurality of fiber holes having a first hole portion and a second hole portion located closer to the rear end face than the first hole portion in the first direction, and the pitch in the second direction of the plurality of first hole portions, each of which is a first hole portion, is greater than the pitch in the second direction of the plurality of second hole portions, each of which is a second hole portion.

[0010] Typically, a ferrule is formed by placing multiple core pins for forming multiple fiber holes in a mold and filling the mold with ferrule material (e.g., molten resin). When filling the mold with the ferrule material, it is difficult for the ferrule material (e.g., molten resin) to fill the gaps between the tip portions of the core pins (the portions for forming the first holes). In contrast, in the above-described ferrule, each of the multiple fiber holes has a first hole portion and a second hole portion located closer to the rear end face than the first hole portion in the first direction, and the pitch of the multiple first hole portions in the second direction is greater than the pitch of the multiple second hole portions in the second direction. In other words, the large pitch of the multiple first hole portions ensures a large gap between the tip portions of the core pins during the ferrule manufacturing process, making it easy to fill the gaps between the tip portions with the ferrule material. This reduces the possibility of unintended unfilled areas of the ferrule material occurring between the first hole portions, and allows fiber holes to be formed in the desired positions and shapes. Therefore, this ferrule prevents degradation of optical characteristics.

[0011] (2) In the ferrule of (1) above, when viewed from the extending direction of the first hole portion, the inner surface of the first hole portion extends along a circle, and when viewed from the extending direction of the second hole portion, the inner surface of the second hole portion extends along a circle, and the inner diameter of the second hole portion may be larger than the inner diameter of the first hole portion. In this case, the end of the optical fiber can be easily inserted into the corresponding first hole portion via the second hole portion.

[0012] (3) In the ferrule of (1) or (2) above, each of the plurality of fiber holes may further have a third hole portion located between the first hole portion and the second hole portion in the first direction, and the pitch of the plurality of third hole portions, each of which is a third hole portion, in the second direction may increase from the plurality of second hole portions to the plurality of first hole portions. In this case, even if the pitch of the first hole portions and the pitch of the second hole portions are different from each other and the first hole portion and the second hole portion cannot be directly connected to each other, the first hole portion and the second hole portion can be connected to each other via the third hole portion.

[0013] (4) In the ferrule of (3) above, the pitch of the first holes may be 235 μm or more and 265 μm or less, and the pitch of the second holes may be 150 μm or more and 180 μm or less. In this case, the large pitch of the first holes can prevent a deterioration in optical characteristics for the reasons described above. Furthermore, the small pitch of the second holes can reduce the width of the bundle of optical fibers drawn from the rear end face of the ferrule in the second direction.

[0014] (5) In the ferrule of (3) or (4) above, when viewed from the extending direction of the first hole portion, the inner surface of the first hole portion extends along a circle, when viewed from the extending direction of the second hole portion, the inner surface of the second hole portion extends along a circle, the inner diameter of the first hole portion may be 110 μm or more and 140 μm or less, and the inner diameter of the second hole portion may be 185 μm or more and 215 μm or less. In this case, the end of the optical fiber can be easily inserted into the fiber hole.

[0015] (6) The ferrule of (1) or (2) above may further include a first side surface and a second side surface positioned to sandwich the plurality of fiber holes in the second direction, and when viewed from the first direction, the center of a first outermost hole portion of the plurality of first hole portions that is closest to the first side surface may be positioned closer to the first side surface than the center of a second outermost hole portion of the plurality of second hole portions that is closest to the first side surface, and when viewed from the first direction, the center of a third outermost hole portion of the plurality of first hole portions that is closest to the second side surface may be positioned closer to the second side surface than the center of a fourth outermost hole portion of the plurality of second hole portions that is closest to the second side surface. In this case, a large pitch between the plurality of first hole portions can be ensured, and degradation of optical characteristics can be prevented for the reasons described above.

[0016] (7) In the ferrule of (6) above, the portion of the inner surface of the first outermost hole closest to the first side surface and the portion of the inner surface of the second outermost hole closest to the first side surface may be located on the same straight line, and the portion of the inner surface of the third outermost hole closest to the second side surface and the portion of the inner surface of the fourth outermost hole closest to the second side surface may be located on the same straight line. In this case, the end of the optical fiber can be easily inserted into the first outermost hole via the second outermost hole. Similarly, the end of the optical fiber can be easily inserted into the third outermost hole via the fourth outermost hole.

[0017] (8) In the ferrule of (6) or (7) above, the pitch of the first hole portions may be 161 μm or more and 191 μm or less, and the pitch of the second hole portions may be 150 μm or more and 180 μm or less. In this case, the large pitch of the first hole portions can prevent a deterioration in optical characteristics for the reasons described above. Furthermore, the small pitch of the second hole portions can reduce the width of the bundle of optical fibers drawn from the rear end face of the ferrule in the second direction.

[0018] (9) In the ferrule of any one of (6) to (8) above, when viewed from the extending direction of the first hole portion, the inner surface of the first hole portion extends along a circle, when viewed from the extending direction of the second hole portion, the inner surface of the second hole portion extends along a circle, the inner diameter of the first hole portion may be 110 μm or more and 140 μm or less, and the inner diameter of the second hole portion may be 235 μm or more and 265 μm or less. In this case, the end of the optical fiber can be easily inserted into the fiber hole.

[0019] (10) An optical connector according to the present disclosure includes a ferrule according to any one of (1) to (9) above and a plurality of optical fibers, each end of which is inserted into a corresponding one of a plurality of fiber holes. This optical connector can prevent degradation of optical characteristics for the reasons described above.

[0020] (11) In the optical connector of (10), each of the plurality of optical fibers may have a glass fiber and a coating layer covering the outer periphery of the glass fiber, the outer diameter of the glass fiber being 110 μm or more and 140 μm or less, and the outer diameter of the coating layer being 150 μm or more and 180 μm or less. In this case, since the optical fiber is a small-diameter fiber with a small outer diameter of the coating layer, the width of the bundle of the plurality of optical fibers drawn out from the rear end face of the ferrule in the second direction can be reduced.

[0021] [Details of the embodiments of the present disclosure] Specific examples of ferrules and optical connectors according to embodiments of the present disclosure will be described below with reference to the drawings. In the following description, identical elements or elements having the same functions will be designated by the same reference numerals, and duplicate explanations will be omitted. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0022] [Optical connector configuration] The configuration of an optical connector 1 according to one embodiment will be described with reference to Fig. 1 to Fig. 4. Fig. 1 is a perspective view showing an optical connector according to this embodiment. Fig. 2 is a cross-sectional view of the optical fiber shown in Fig. 1. Fig. 3 is a cross-sectional view of the ferrule taken along line III-III shown in Fig. 1. Fig. 4 is a diagram showing the front end face of the ferrule shown in Fig. 1. Fig. 5 is a cross-sectional view of the ferrule showing the configuration of a plurality of second hole portions.

[0023] The optical connector 1 is optically connected to an external mating optical connector. In the following description, the connection direction of the optical connector 1 is referred to as the X-axis direction (first direction), a direction perpendicular to the X-axis direction is referred to as the Y-axis direction (second direction), and a direction perpendicular to the X-axis and Y-axis directions is referred to as the Z-axis direction (third direction). The optical connector 1 includes a plurality of optical fibers 2 and a ferrule 3.

[0024] The plurality of optical fibers 2 transmit input light (optical signals). In this example, the number of the plurality of optical fibers 2 is 12. The number of optical fibers 2 is not limited. An end 2a of each optical fiber 2 extends along the X-axis direction. As shown in FIG. 2, each optical fiber 2 has a glass fiber 21 and a coating layer 22.

[0025] The glass fiber 21 includes a core 23 and a clad 24 surrounding the core 23. The clad 24 has a different refractive index from that of the core 23. The refractive index of the core 23 is higher than that of the clad 24. As a result, light input to the optical fiber 2 is guided in the core 23. The cross sections of the optical fiber 2 and the glass fiber 21 are circular. In this example, the outer diameter of the glass fiber 21 is approximately 125 μm. The outer diameter of the glass fiber 21 may be 110 μm or more and 140 μm or less.

[0026] The coating layer 22 covers the outer periphery of the glass fiber 21. The coating layer 22 is formed in a cylindrical shape. A portion of the end of the coating layer 22 is removed from the optical fiber 2. That is, the end of the glass fiber 21 has an exposed portion that is not covered with the coating layer 22. The exposed portion of the glass fiber 21 is located closer to the tip surface of the optical fiber 2 than the portion of the glass fiber 21 that is covered with the coating layer 22. The exposed portion of the glass fiber 21 is inserted into a first hole portion 41 of a fiber hole 31, which will be described later. The coating layer 22 is formed of, for example, resin.

[0027] The optical fiber 2 is a thin fiber with a small coating diameter. In this example, the outer diameter of the coating layer 22 is approximately 165 μm. The outer diameter of the coating layer 22 may be 150 μm or more and 180 μm or less. The thickness of the coating layer 22 is approximately 20 μm. The ends 2 a of the multiple optical fibers 2 are arranged side by side in the Y-axis direction. The end 2 a of each optical fiber 2 is spaced apart from the end 2 a of an adjacent optical fiber 2 without contacting each other.

[0028] The ferrule 3 is, for example, an MT ferrule. The ferrule 3 holds end portions 2a of a plurality of optical fibers 2. The ferrule 3 is formed in a substantially rectangular parallelepiped shape. In this example, the ferrule 3 is made of resin. The ferrule 3 has a front end face 3a, a rear end face 3b, a side face 3c (first side face), a side face 3d (second side face), a main face 3e, and a main face 3f. The rear end face 3b is located on the opposite side of the front end face 3a in the X-axis direction. The side face 3d is located on the opposite side of the side face 3c in the Y-axis direction. The side faces 3c and 3d are located in the Y-axis direction so as to sandwich a plurality of fiber holes 31, which will be described later. The main face 3f is located on the opposite side of the main face 3e in the Z-axis direction.

[0029] The front end face 3a is a surface that abuts against the ferrule of a mating optical connector to be connected to the optical connector 1 in the X-axis direction. In this example, the front end face 3a extends along the Z-axis direction, but the front end face 3a may be inclined with respect to the Z-axis direction so that it approaches the rear end face 3b as it moves from the main face 3e to the main face 3f. In this case, the inclination angle of the front end face 3a with respect to the Z-axis direction may be, for example, 8 degrees.

[0030] The ferrule 3 has a plurality of fiber holes 31, a plurality of grooves 32, an internal space 33, and a pair of guide holes 34. The plurality of fiber holes 31 have a hollow shape and open at the front end face 3a. The plurality of fiber holes 31 are aligned in the Y-axis direction. An end 2a of a corresponding optical fiber 2 can be inserted into each fiber hole 31. Each of the plurality of fiber holes 31 includes a first hole portion 41, a second hole portion 42, a third hole portion 43, and a tapered portion 44. That is, the ferrule 3 includes a plurality of first hole portions 41, a plurality of second hole portions 42, a plurality of third hole portions 43, and a plurality of tapered portions 44.

[0031] Each of the multiple first holes 41 is a hole extending along the X-axis direction. The length of each first hole 41 along the X-axis direction is, for example, approximately 500 μm. The length of each first hole 41 along the X-axis direction may be 200 μm or more, 300 μm or more, or 500 μm or more. One end of each first hole 41 opens to the front end face 3a, and the other end is connected to the corresponding third hole 43. As shown in FIG. 4 , each first hole 41 can receive an end 2a of a corresponding optical fiber 2 among the multiple optical fibers 2. That is, one optical fiber 2 is inserted into one first hole 41. In this example, the exposed portion of the glass fiber 21 that is not covered with the coating layer 22 is inserted into the first hole 41. For ease of explanation, FIG. 4 illustrates only the optical fibers 2 inserted into three of the multiple first holes 41, and does not illustrate the optical fibers 2 inserted into the other first holes 41.

[0032] When viewed from the extension direction of the first hole portion 41 (X-axis direction), the inner surface 41a of the first hole portion 41 extends along a circle centered on an axis along the X-axis direction. That is, in a cross section perpendicular to the extension direction of the first hole portion 41, the inner surface 41a follows a circle. In this example, the inner diameter of the first hole portion 41 (the diameter of the circle along which the inner surface 41a follows) is approximately 125 μm. The inner diameter of the first hole portion 41 may be 110 μm or more and 140 μm or less. The inner diameter of the first hole portion 41 approximately matches the outer diameter of the glass fiber 21. The distance between the inner surfaces 41a of adjacent first hole portions 41 (shortest distance in the Y-axis direction) is approximately 125 μm.

[0033] The multiple first hole portions 41 are arranged at predetermined intervals in the Y-axis direction. In this example, the pitch P1 of the multiple first hole portions 41 in the Y-axis direction is approximately 250 μm. The pitch P1 of the first hole portions 41 is the distance in the Y-axis direction between the centers C1 of adjacent first hole portions 41. The pitch P1 of the first hole portions 41 may be, for example, not less than 235 μm and not more than 265 μm. In this example, the pitch P1 of the multiple first hole portions 41 is constant. That is, the multiple first hole portions 41 are formed at equal intervals in the Y-axis direction.

[0034] The second holes 42 are located closer to the rear end face 3b in the X-axis direction than the first holes 41, the third holes 43, and the tapered portions 44. In the direction from the front end face 3a to the rear end face 3b, the first holes 41, the third holes 43, the tapered portions 44, and the second holes 42 are located in this order. Each of the second holes 42 is a hole extending along the X-axis direction. One end of each second hole 42 is connected to the corresponding tapered portion 44, and the other end is connected to the corresponding groove portion 32. An end portion 2a of a corresponding optical fiber 2 among the multiple optical fibers 2 can be inserted into each second hole 42. That is, one optical fiber 2 is inserted into each second hole 42. In this example, a portion of the glass fiber 21 covered with the coating layer 22 is inserted into the second hole 42. Furthermore, in this example, an exposed portion of the glass fiber 21 not covered with the coating layer 22 is also inserted into the second hole 42. That is, the boundary between the portion of the glass fiber 21 that is covered with the coating layer 22 and the exposed portion that is not covered with the coating layer 22 is located inside the second hole portion 42 .

[0035] When viewed from the extension direction of the second hole 42 (X-axis direction), the inner surface 42a of the second hole 42 extends (in an arc shape) along a circle whose center is an axis along the X-axis direction. That is, in a cross section perpendicular to the extension direction of the second hole 42, the inner surface 42a follows a circle. In this example, the inner diameter of the second hole 42 (the diameter of the circle along which the inner surface 42a follows) is approximately 200 μm. The inner diameter of the second hole 42 may be 185 μm or more and 215 μm or less. The inner diameter of the second hole 42 is larger than the inner diameter of the first hole 41. The inner diameter of the second hole 42 is larger than the outer diameter of the coating layer 22 of the optical fiber 2.

[0036] The multiple second hole portions 42 are aligned without any gaps in the Y-axis direction. That is, adjacent second hole portions 42 among the multiple second hole portions 42 are connected to each other in the Y-axis direction. More specifically, adjacent second hole portions 42 are directly connected to each other in space without any intervening space. When viewed from the X-axis direction, a circle along the inner surface 42a of each second hole portion 42 overlaps with a circle along the inner surface 42a of an adjacent second hole portion 42. That is, the inner surface 42a of each second hole portion 42 is directly connected to the inner surface 42a of an adjacent second hole portion 42.

[0037] The pitch P2 of the second hole portions 42 in the Y-axis direction is smaller than the pitch P1 of the first hole portions 41 in the Y-axis direction. The pitch P2 of the second hole portions 42 is the distance in the Y-axis direction between the centers C2 of adjacent second hole portions 42. That is, the pitch P1 of the first hole portions 41 in the Y-axis direction is larger than the pitch P2 of the second hole portions 42 in the Y-axis direction. In this example, the pitch P2 of the second hole portions 42 is approximately 165 μm. The pitch P2 of the second hole portions 42 may be, for example, not less than 150 μm and not more than 180 μm. In this example, the pitch P2 of the second hole portions 42 is constant. That is, the second hole portions 42 are formed at equal intervals in the Y-axis direction.

[0038] Each of the multiple third hole portions 43 is located between the first hole portion 41 and the second hole portion 42 in the X-axis direction. In the direction from the front end face 3a toward the rear end face 3b, the multiple first hole portions 41, the multiple third hole portions 43, and the multiple second hole portions 42 are located in this order. One end of each third hole portion 43 is connected to the corresponding first hole portion 41, and the other end is connected to the corresponding second hole portion 42 via a tapered portion 44. That is, each third hole portion 43 includes an end portion E1 connected to the first hole portion 41 and an end portion E2 connected to the second hole portion 42. The end portion E2 is indirectly connected to the second hole portion 42 via the tapered portion 44.

[0039] An end portion 2a of a corresponding optical fiber 2 among the plurality of optical fibers 2 can be inserted into each third hole portion 43. That is, one optical fiber 2 is inserted into one third hole portion 43. In this example, an exposed portion of the glass fiber 21 that is not covered with the coating layer 22 is inserted into the third hole portion 43.

[0040] When viewed from the extending direction of the third hole portion 43, the inner surface 43a of the third hole portion 43 extends along a circle whose center is an axis along the extending direction of the third hole portion 43. That is, in a cross section perpendicular to the extending direction of the third hole portion 43, the inner surface 43a follows a circle. In this example, the inner diameter of the third hole portion 43 (the diameter of the circle along which the inner surface 43a follows) is approximately 125 μm. The inner diameter of the third hole portion 43 may be 110 μm or more and 140 μm or less. The inner diameter of the third hole portion 43 is equal to the inner diameter of the first hole portion 41. The inner diameter of the third hole portion 43 approximately matches the outer diameter of the glass fiber 21.

[0041] The third hole portions 43 are formed such that the spacing between them in the Y-axis direction increases from the rear end surface 3b toward the front end surface 3a. The pitch of the third hole portions 43 in the Y-axis direction increases from the second hole portions 42 toward the first hole portions 41. The pitch of the third hole portions 43 in the Y-axis direction is the distance in the Y-axis direction between the centers of adjacent third hole portions 43. The pitch of the third hole portions 43 at the end E1 is greater than the pitch of the third hole portions 43 at the end E2. The pitch of the third hole portions 43 at the end E1 matches the pitch P1 of the first hole portions 41. The pitch of the third hole portions 43 at the end E2 matches the pitch P2 of the second hole portions 42.

[0042] The multiple tapered portions 44 are holes formed between the multiple third hole portions 43 and the multiple second hole portions 42 in the X-axis direction. The multiple tapered portions 44 are aligned in the Y-axis direction. One end of each tapered portion 44 is connected to the corresponding first hole portion 41, and the other end is connected to the corresponding second hole portion 42. An end portion 2a of a corresponding optical fiber 2 among the multiple optical fibers 2 can be inserted into each tapered portion 44. That is, one optical fiber 2 is inserted into one tapered portion 44. In this example, an exposed portion of the glass fiber 21 that is not covered with the coating layer 22 is inserted into the tapered portion 44.

[0043] The tapered portion 44 has a tapered shape in which the inner diameter decreases from the rear end surface 3b toward the front end surface 3a. The inner diameter of the end of the tapered portion 44 connected to the second hole portion 42 matches the inner diameter of the second hole portion 42, and the inner diameter of the end of the tapered portion 44 connected to the third hole portion 43 matches the inner diameter of the third hole portion 43 (first hole portion 41). The pitch of the tapered portions 44 in the Y-axis direction matches the pitch P2 of the second hole portions 42. The pitch of the tapered portions 44 in the Y-axis direction is the distance in the Y-axis direction between the centers of adjacent tapered portions 44.

[0044] The multiple grooves 32 are formed on the inner surface of the ferrule 3 at positions closer to the rear end face 3b in the X-axis direction than the multiple second holes 42. Each groove 32 extends along the X-axis direction. Each groove 32 is recessed in a direction from the main surface 3e toward the main surface 3f of the ferrule 3. One end of each groove 32 is connected to the corresponding second hole 42, and the other end is connected to an internal space 33, which will be described later. In each groove 32, an end 2a of a corresponding optical fiber 2 among the multiple optical fibers 2 can be placed. In other words, one optical fiber 2 is placed in one groove 32.

[0045] When viewed from the X-axis direction, the inner surfaces 32a of the groove portions 32 coincide with the inner surfaces 42a of the corresponding second hole portions 42. That is, when viewed from the X-axis direction, the inner surfaces 32a of the groove portions 32 extend (in an arc shape) along a circle whose center is an axis along the X-axis direction. The pitch of the groove portions 32 in the Y-axis direction coincides with the pitch P2 of the second hole portions 42. The pitch of the groove portions 32 in the Y-axis direction is the distance in the Y-axis direction between the centers of adjacent groove portions 32 (the centers of the circles along which the inner surfaces 32a follow).

[0046] The internal space 33 is a housing portion capable of housing a plurality of optical fibers 2. The internal space 33 opens to the rear end face 3b and is spatially connected to the plurality of fiber holes 31. The internal space 33 is spatially connected to the outside of the ferrule 3 via a window portion 35 that opens to the main surface 3e of the ferrule 3. The internal space 33 houses a portion of the optical fiber 2 that is covered with the coating layer 22.

[0047] The end portions 2a of the multiple optical fibers 2 are accommodated in the internal space 33 through the opening in the rear end face 3b. The end portion 2a of each optical fiber 2 accommodated in the internal space 33 is placed in the corresponding groove portion 32, and then inserted into the second hole portion 42, the tapered portion 44, the third hole portion 43, and the first hole portion 41 in that order. That is, the end portions 2a of each of the multiple optical fibers 2 are inserted into the corresponding fiber hole 31. The tip surface of the optical fiber 2 inserted into the first hole portion 41 is exposed to the outside of the ferrule 3 from the opening of the first hole portion 41 in the front end face 3a.

[0048] The ferrule 3 is disposed in the internal space 33 and further includes an adhesive (not shown) for fixing the plurality of optical fibers 2 to the ferrule 3. The adhesive may be injected into the internal space 33 through the window 35. The adhesive may be disposed so as to reach the groove 32 and the fiber hole 31.

[0049] The pair of guide holes 34 are positioned so as to sandwich the plurality of fiber holes 31 in the Y-axis direction. Each guide hole 34 extends in the X-axis direction and opens to the front end face 3a and the rear end face 3b. A guide pin (not shown) for aligning the optical connector 1 with the mating optical connector is inserted into each guide hole 34. One end of the guide pin is inserted into each guide hole 34 from the opening formed in the front end face 3a. The other end of the guide pin is inserted into a guide hole formed in the mating optical connector. The guide holes 34 and the guide pins inserted into the guide holes 34 function as positioning parts for positioning the optical connector 1 with the mating optical connector.

[0050] [Ferrule manufacturing method] In the manufacturing process of the ferrule 3, first, a mold for the ferrule 3 is prepared. The mold for the ferrule 3 has, for example, a shape corresponding to the outer shape of the ferrule 3. Next, a plurality of core pins having a shape corresponding to the shape of the fiber holes 31 are placed in the mold (internal space of the mold). At this time, a catcher that holds the end of the core pin may be used to fix the core pin.

[0051] Next, the material of the ferrule 3 is filled into the mold for the ferrule 3, and the ferrule 3 is molded (injection molding is performed). Specifically, the material of the ferrule 3 (resin in this example) is melted, and the molten material is filled into the mold. The molten material of the ferrule 3 is filled into the mold so as to cover the core pin. Next, the filled material is cooled and hardened. After the material has hardened, the mold and core pin are removed. In this way, the ferrule 3 is formed. When removing the core pin, there is a risk that the hardened material of the ferrule 3 (resin-filled portion) and the core pin will interfere with each other. For this reason, the core pin may be made of a highly tough material.

[0052] When the material of the ferrule 3 is filled into the mold, the area where the core pin is located is not filled with the material of the ferrule 3. Therefore, when the core pin is removed, the area where the core pin was located is formed as a hollow area in the ferrule 3. The area where the core pin was located corresponds to the fiber hole 31 and the groove portion 32.

[0053] Generally, a ferrule is formed by placing multiple core pins for forming multiple fiber holes in a mold and filling the mold with ferrule material (e.g., molten resin). When filling the mold with the ferrule material, it is difficult for the ferrule material (e.g., molten resin) to fill the spaces between the tip portions of the core pins (portions for forming the first holes). In contrast, in the optical connector 1 and the ferrule 3, each of the multiple fiber holes 31 has a first hole portion 41 and a second hole portion 42 located closer to the rear end face 3b in the X-axis direction than the first hole portion 41, and the pitch P1 of the multiple first hole portions 41 in the Y-axis direction is larger than the pitch P2 of the multiple second hole portions 42 in the Y-axis direction. In other words, because the pitch P1 of the multiple first hole portions 41 is large, a large gap can be secured between the tip portions of the core pins during the manufacturing process of the ferrule 3, making it easy to fill the spaces between the tip portions with the ferrule material. This reduces the possibility of unintended unfilled regions (air traps, weld lines, etc.) of the ferrule 3 material occurring between the first hole portions 41, and allows the fiber holes 31 to be formed in the desired positions and shapes (improved mold transferability). Therefore, the optical connector 1 and ferrule 3 can prevent degradation of optical characteristics.

[0054] In particular, in ferrules used with small-diameter fibers having small coating diameters, the spacing between the multiple fiber holes becomes narrow, which in turn narrows the spacing between the core pins used in the ferrule manufacturing process. The inventors determined through resin flow analysis that the narrower the spacing between the core pins, the more likely it is that material will not be properly filled between the core pins (especially between the tip portions), resulting in unintended areas of the ferrule that are unfilled with material. In the ferrule 3, the pitch P1 between the multiple first hole portions 41 is intentionally kept large, which makes it less likely that unintended areas of the ferrule 3 that are unfilled with material will occur, even when a small-diameter fiber is used, and thus prevents a deterioration in optical characteristics.

[0055] When viewed from the extension direction of the first hole portion 41 (X-axis direction), the inner surface 41a of the first hole portion 41 extends along a circle. When viewed from the extension direction of the second hole portion 42 (X-axis direction), the inner surface 42a of the second hole portion 42 extends along a circle. The inner diameter of the second hole portion 42 is larger than the inner diameter of the first hole portion 41. This allows the end portion 2a of the optical fiber 2 to be easily inserted into the corresponding first hole portion 41 via the second hole portion 42.

[0056] Each of the plurality of fiber holes 31 has a third hole portion 43 located between the first hole portion 41 and the second hole portion 42 in the X-axis direction. The pitch of the plurality of third hole portions 43 in the Y-axis direction increases from the plurality of second hole portions 42 toward the plurality of first hole portions 41. As a result, even if the pitch P1 of the first hole portions 41 and the pitch P2 of the second hole portions 42 are different from each other and therefore the first hole portion 41 and the second hole portion 42 cannot be directly connected to each other, the first hole portion 41 and the second hole portion 42 can be connected to each other via the third hole portion 43.

[0057] The pitch P1 of the multiple first holes 41 may be 235 μm or more and 265 μm or less. The pitch P2 of the multiple second holes 42 may be 150 μm or more and 180 μm or less. In this case, since the pitch P1 of the multiple first holes 41 is large, it is possible to prevent a deterioration in optical characteristics for the reasons described above. Furthermore, since the pitch P2 of the multiple second holes 42 is small, it is possible to reduce the width along the Y-axis direction of the bundle of multiple optical fibers 2 drawn out from the rear end face 3b of the ferrule 3.

[0058] The inner diameter of the first hole 41 may be 110 μm or more and 140 μm or less. The inner diameter of the second hole 42 may be 185 μm or more and 215 μm or less. In this case, the end 2 a of the optical fiber 2 can be easily inserted into the fiber hole 31.

[0059] Each of the multiple optical fibers 2 has a glass fiber 21 and a coating layer 22 that covers the outer periphery of the glass fiber 21. The outer diameter of the glass fiber 21 may be 110 μm or more and 140 μm or less. The outer diameter of the coating layer 22 may be 150 μm or more and 180 μm or less. In this case, because the optical fiber 2 is a small-diameter fiber with a small outer diameter of the coating layer 22, the width along the Y-axis direction of the bundle of multiple optical fibers 2 drawn out from the rear end face 3b of the ferrule 3 can be reduced.

[0060] Each of the multiple first hole portions 41 extends along the X-axis direction. This makes it possible to prevent the positions of the openings of the first hole portions 41 (fiber holes 31) in the front end face 3a from changing along the Y-axis direction when the front end face 3a is polished. The front end face 3a may be polished to set the inclination angle of the front end face 3a with respect to the Z-axis direction to, for example, 8 degrees.

[0061] [Second embodiment] The configuration of an optical connector 1 according to a second embodiment will be described with reference to Figs. 6 to 8. Fig. 6 is a diagram showing an optical connector according to the second embodiment. In Fig. 6, a plurality of second holes are indicated by dashed lines. Fig. 7 is a cross-sectional view of the ferrule taken along line VII-VII shown in Fig. 6. Fig. 8 is a cross-sectional view of the ferrule taken along line VIII-VIII shown in Fig. 6. The optical connector 1 according to the second embodiment includes a ferrule 3A instead of the ferrule 3. Below, differences between the ferrule 3A and the ferrule 3 will be mainly described, and explanations of commonalities may be omitted.

[0062] In the second embodiment, each fiber hole 31 does not have a third hole portion 43, and has a first hole portion 141 instead of the first hole portion 41. That is, the ferrule 3A has a plurality of first hole portions 141.

[0063] Each of the multiple first hole portions 141 is a hole extending along the X-axis direction. One end of each first hole portion 141 opens to the front end face 3a, and the other end is connected to the corresponding tapered portion 44. As shown in FIG. 6, an end portion 2a of a corresponding optical fiber 2 among the multiple optical fibers 2 can be inserted into each first hole portion 141. That is, one optical fiber 2 is inserted into one first hole portion 141. In this example, an exposed portion of the glass fiber 21 that is not covered with the coating layer 22 is inserted into the first hole portion 141. For ease of explanation, FIG. 6 illustrates only the optical fibers 2 inserted into two of the multiple first hole portions 141, and does not illustrate the optical fibers 2 inserted into the other first hole portions 141.

[0064] When viewed from the extension direction (X-axis direction) of the first hole portion 141, the inner surface 141a of the first hole portion 141 extends along a circle whose center is an axis along the X-axis direction. That is, in a cross section perpendicular to the extension direction of the first hole portion 141, the inner surface 141a follows a circle. In this example, the inner diameter of the first hole portion 141 (the diameter of the circle along which the inner surface 141a follows) is about 125 μm. The inner diameter of the first hole portion 141 may be 110 μm or more and 140 μm or less. The inner diameter of the first hole portion 141 approximately matches the outer diameter of the glass fiber 21.

[0065] When viewed from the extension direction of the second hole portion 42 (X-axis direction), the inner surface 42a of the second hole portion 42 extends along a circle whose center is an axis along the X-axis direction. That is, in a cross section perpendicular to the extension direction of the second hole portion 42, the inner surface 42a follows a circle. In this embodiment, the inner diameter of the second hole portion 42 (the diameter of the circle along which the inner surface 42a follows) is approximately 250 μm. The inner diameter of the second hole portion 42 may be 235 μm or more and 265 μm or less.

[0066] In this embodiment, one end of the tapered portion 44 is connected to the corresponding first hole portion 141, and the other end is connected to the corresponding second hole portion 42. The tapered portion 44 has a tapered shape in which the inner diameter decreases from the rear end face 3b toward the front end face 3a. The inner diameter of the end of the tapered portion 44 connected to the second hole portion 42 matches the inner diameter of the second hole portion 42, and the inner diameter of the end of the tapered portion 44 connected to the first hole portion 141 matches the inner diameter of the first hole portion 141. The pitch of the tapered portion 44 in the Y-axis direction matches the pitch P1 of the first hole portions 141, which will be described later.

[0067] The side surface 3c (first side surface) and the side surface 3d (second side surface) of the ferrule 3A are positioned in the Y-axis direction so as to sandwich the plurality of fiber holes 31. The plurality of first hole portions 141, the plurality of second hole portions 42, and the plurality of tapered portions 44 are positioned between the side surface 3c and the side surface 3d in the Y-axis direction.

[0068] 6, when viewed from the X-axis direction, the center C1 of the first hole portion 141A (first outermost hole portion), which is closest to the side surface 3c among the multiple first hole portions 141, is located closer to the side surface 3c than the center C2 of the second hole portion 42A (second outermost hole portion), which is closest to the side surface 3c among the multiple second hole portions 42. In this example, the center C1 is the center of the circle that the inner surface 141a follows, and the center C2 is the center of the circle that the inner surface 42a follows. When viewed from the X-axis direction, the center C1 of the first hole portion 141B (third outermost hole portion), which is closest to the side surface 3d among the multiple first hole portions 141, is located closer to the side surface 3d than the center C2 of the second hole portion 42B (fourth outermost hole portion), which is closest to the side surface 3d among the multiple second hole portions 42.

[0069] A portion 141b of the inner surface 141a of the first hole portion 141A that is closest to the side surface 3c and a portion 42b of the inner surface 42a of the second hole portion 42A that is closest to the side surface 3c are located on the same straight line (straight line L1). The portion 141b is the portion of the inner surface 141a of the first hole portion 141A that is closest to the side surface 3c in the Y-axis direction. The portion 42b is the portion of the inner surface 42a of the second hole portion 42A that is closest to the side surface 3c in the Y-axis direction. In this example, the straight line L1 is along the X-axis direction.

[0070] A portion 141c of the inner surface 141a of the first hole portion 141B that is closest to the side surface 3d and a portion 42c of the inner surface 42a of the second hole portion 42B that is closest to the side surface 3d are located on the same straight line (straight line L2). The portion 141c is the portion of the inner surface 141a of the first hole portion 141B that is closest to the side surface 3d in the Y-axis direction. The portion 42c is the portion of the inner surface 42a of the second hole portion 42B that is closest to the side surface 3d in the Y-axis direction. In this example, the straight line L2 is along the X-axis direction.

[0071] The multiple tapered portions 44 include tapered portion 44A located closest to side surface 3c and tapered portion 44B located closest to side surface 3d. Portion 44b of the inner surface 44a of tapered portion 44A, which is closest to side surface 3c, portion 141b, and portion 42b, are located on the same straight line. Portion 44b is the portion of the inner surface 44a of tapered portion 44A that is closest to side surface 3c in the Y-axis direction. In this example, portions 44b, 141b, and 42b are located on a straight line L1. Portion 44c of the inner surface 44a of tapered portion 44B, which is closest to side surface 3d, portion 141c, and portion 42c are located on the same straight line. Portion 44c is the portion of the inner surface 44a of tapered portion 44B that is closest to side surface 3d in the Y-axis direction. In this example, portions 44c, 141c, and 42c are located on a straight line L1.

[0072] The plurality of fiber holes 31 include a fiber hole 31A located closest to the side surface 3c and a fiber hole 31B located closest to the side surface 3d. In this example, the fiber hole 31A is composed of a first hole portion 141A, a second hole portion 42A, and a tapered portion 44A. The inner surface 31a of the fiber hole 31A has a portion 31b (portion 141b, portion 42b, and portion 44b) along a straight line L1 along the X-axis direction. The fiber hole 31B is composed of a first hole portion 141B, a second hole portion 42B, and a tapered portion 44B. The inner surface 31a of the fiber hole 31B has a portion 31c (portion 141c, portion 42c, and portion 44c) along a straight line L2 along the X-axis direction.

[0073] The multiple first hole portions 141 are arranged at predetermined intervals in the Y-axis direction. In this embodiment, the pitch P1 of the multiple first hole portions 141 in the Y-axis direction is approximately 176 μm. The pitch P1 of the first hole portions 141 is the distance in the Y-axis direction between the centers C1 of adjacent first hole portions 141. The pitch P1 of the first hole portions 141 may be, for example, not less than 161 μm and not more than 191 μm. The distance between the inner surfaces 141a of adjacent first hole portions 141 (shortest distance in the Y-axis direction) is approximately 50 μm.

[0074] The pitch P2 of the multiple second hole portions 42 in the Y-axis direction is smaller than the pitch P1 of the multiple first hole portions 141 in the Y-axis direction. That is, the pitch P1 of the multiple first hole portions 141 in the Y-axis direction is larger than the pitch P2 of the multiple second hole portions 42 in the Y-axis direction. In this embodiment, the pitch P2 of the second hole portions 42 is approximately 165 μm. The pitch P2 of the second hole portions 42 may be, for example, not less than 150 μm and not more than 180 μm.

[0075] The ferrule 3A has side surfaces 3c and 3d positioned to sandwich the plurality of fiber holes 31 in the Y-axis direction. When viewed from the X-axis direction, the center C1 of the first hole 141A, which is closest to the side surface 3c among the plurality of first hole portions 141, is located closer to the side surface 3c than the center C2 of the second hole 42A, which is closest to the side surface 3c among the plurality of second hole portions 42. When viewed from the X-axis direction, the center C1 of the first hole 141B, which is closest to the side surface 3d among the plurality of first hole portions 141, is located closer to the side surface 3d than the center C2 of the second hole 42B, which is closest to the side surface 3d among the plurality of second hole portions 42. This ensures a large pitch P1 between the plurality of first hole portions 141. This reduces the possibility of unintended unfilled regions between the first hole portions 141, and allows the fiber holes 31 to be formed in the desired positions and shapes. Therefore, the ferrule 3A can prevent degradation of optical characteristics.

[0076] A portion 141b of the inner surface 141a of the first hole 141A that is closest to the side surface 3c and a portion 42b of the inner surface 42a of the second hole 42A that is closest to the side surface 3c are located on the same straight line (straight line L1). A portion 141c of the inner surface 141a of the first hole 141B that is closest to the side surface 3d and a portion 42c of the inner surface 42a of the second hole 42B that is closest to the side surface 3d are located on the same straight line (straight line L2). This allows the end 2a of the optical fiber 2 to be easily inserted into the first hole 141A via the second hole 42A. Similarly, the end 2a of the optical fiber 2 can be easily inserted into the first hole 141B via the second hole 42B. Specifically, there is no gap in the Y-axis direction between portion 141b of first hole portion 141A and portion 42b of second hole portion 42A, and portion 141b and portion 42b are connected flatly via portion 44b of tapered portion 44. Therefore, end portion 2a of optical fiber 2 can be easily inserted into first hole portion 141A via second hole portion 42A. Also, damage to optical fiber 2 during insertion can be prevented. The same applies to insertion of optical fiber 2 into first hole portion 141B and second hole portion 42B.

[0077] The pitch P1 of the multiple first holes 141 may be 161 μm or more and 191 μm or less. The pitch P2 of the multiple second holes 42 may be 150 μm or more and 180 μm or less. In this case, since the pitch P1 of the multiple first holes 141 is large, it is possible to prevent a deterioration in optical characteristics for the reasons described above. Furthermore, since the pitch P2 of the multiple second holes 42 is small, it is possible to reduce the width along the Y-axis direction of the bundle of multiple optical fibers 2 drawn out from the rear end face 3b of the ferrule 3A.

[0078] When viewed from the extension direction of the first hole portion 141 (X-axis direction), the inner surface 141a of the first hole portion 141 extends along a circle. When viewed from the extension direction of the second hole portion 42 (X-axis direction), the inner surface 42a of the second hole portion 42 extends along a circle. The inner diameter of the first hole portion 141 may be 110 μm or more and 140 μm or less. The inner diameter of the second hole portion 42 may be 235 μm or more and 265 μm or less. In this case, the end portion 2a of the optical fiber 2 can be easily inserted into the fiber hole 31.

[0079] Although the embodiments have been described above, the present disclosure is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure. In addition, the above-described embodiments may be combined as appropriate.

[0080] 9, in a ferrule 3A, the bottom 141d of the first hole 141, the bottom 42d of the second hole 42, and the bottom 44d of the tapered portion 44 may be located on the same straight line (straight line L3). The bottom 141d of the first hole 141 is the portion of the inner surface 141a of the first hole 141 that is closest to the main surface 3f of the ferrule 3. The bottom 42d of the second hole 42 is the portion of the inner surface 42a of the second hole 42 that is closest to the main surface 3f. The bottom 44d of the tapered portion 44 is the portion of the inner surface 44a of the tapered portion 44 that is closest to the main surface 3f. In this example, the straight line L3 is along the X-axis direction. The bottom 32d of the groove 32 may be located on the same straight line (straight line L3) as the bottom 42d of the second hole 42. The bottom 32d of the groove 32 is the portion of the inner surface 32a of the groove 32 that is closest to the main surface 3f. This allows the end 2a of the optical fiber 2 to be easily inserted into the fiber hole 31 via the groove 32. Specifically, there are no steps (gaps) in the Z-axis direction between the bottom 141d of the first hole 141, the bottom 42d of the second hole 42, the bottom 44d of the tapered portion 44, and the bottom 32d of the groove 32, and the bottoms are connected flat. Therefore, after the end 2a of the optical fiber 2 is inserted into the fiber hole 31 via the groove 32, it can be easily inserted from the second hole 42 into the first hole 141. Furthermore, if a step is formed at the bottom, the optical fiber 2 may collide with the step and be damaged when inserted. However, the ferrule 3A according to this modification can prevent such damage to the optical fiber 2.

[0081] When viewed from the extension direction of the first hole portion 41, the inner surface 41a of the first hole portion 41 may extend along a shape other than a circle (for example, an ellipse, a polygon, etc.). When viewed from the extension direction of the first hole portion 141, the inner surface 141a of the first hole portion 141 may extend along a shape other than a circle (for example, an ellipse, a polygon, etc.). When viewed from the extension direction of the second hole portion 42, the inner surface 42a of the second hole portion 42 may extend along a shape other than a circle (for example, an ellipse, a polygon, etc.). When viewed from the extension direction of the third hole portion 43, the inner surface 43a of the third hole portion 43 may extend along a shape other than a circle (for example, an ellipse, a polygon, etc.).

[0082] In the ferrule 3, the pitch P1 of the first hole portions 41 may be smaller than 235 μm or larger than 265 μm. The pitch P2 of the second hole portions 42 may be smaller than 150 μm or larger than 180 μm. In the ferrule 3A, the pitch P1 of the first hole portions 141 may be smaller than 161 μm or larger than 191 μm. The pitch P2 of the second hole portions 42 may be smaller than 150 μm or larger than 180 μm.

[0083] In the ferrule 3, the inner diameter of the first hole portion 41 may be smaller than 110 μm or larger than 140 μm. The inner diameter of the second hole portion 42 may be smaller than 185 μm or larger than 215 μm. In the ferrule 3A, the inner diameter of the first hole portion 141 may be smaller than 110 μm or larger than 140 μm. The inner diameter of the second hole portion 42 may be smaller than 235 μm or larger than 265 μm.

[0084] In the ferrule 3A, the portion 141b of the first hole portion 141A and the portion 42b of the second hole portion 42A do not have to be positioned on the same straight line (straight line L1). The portion 141c of the first hole portion 141B and the portion 42c of the second hole portion 42B do not have to be positioned on the same straight line (straight line L2).

[0085] The outer diameter of the glass fiber 21 may be smaller than 110 μm or larger than 140 μm, and the outer diameter of the coating layer 22 may be smaller than 150 μm or larger than 180 μm.

[0086] Only the exposed portion of the glass fiber 21 that is not covered with the coating layer 22 may be inserted into the second hole 42. That is, the boundary between the portion of the glass fiber 21 that is covered with the coating layer 22 and the exposed portion that is not covered with the coating layer 22 may be located within the groove 32 or the internal space 33. [Explanation of symbols]

[0087] 1...Optical connector 2...Optical fiber 2a...end 3...Ferrule 3a...front end surface 3A...Ferrule 3b…Rear end surface 3c...side 3d...side 3e...Main surface 3f…Main surface 21...Glass fiber 22…Covering layer 23...Core 24...Clad 31...Fiber hole 31A...Fiber hole 31a...Inside 31B...Fiber hole 31b…part 31c...part 32...Groove 32a...Inside 32d…Bottom 33...Interior space 34...Guide hole 35...Window section 41...First hole 41a...Inside 42...Second hole 42a...Inner surface 42A…Second hole 42B…Second hole 42b…part 42c…part 42d…Bottom 43...Third hole 43a...Inner surface 44...Tapered section 44A...Tapered section 44a...Inner surface 44B...Tapered section 44b…part 44c…part 44d…Bottom 141...First hole 141a...Inner 141A…First hole 141B…First hole 141b…part 141c… part 141d…bottom C1…Center C2…Center E1…end E2…end L1… Straight line L2… Straight line L3… Straight line P1…ピッチ P2…ピッチ

Claims

1. A front end surface and a rear end surface located on the opposite side to the front end surface in the first direction; a plurality of fiber holes that open in the front end surface and are aligned in a second direction that intersects with the first direction, each of the plurality of fiber holes has a first hole portion and a second hole portion located closer to the rear end face than the first hole portion in the first direction; a pitch in the second direction of the plurality of first hole portions, each of which is the first hole portion, is larger than a pitch in the second direction of the plurality of second hole portions, each of which is the second hole portion; Ferrule.

2. When viewed from the extending direction of the first hole portion, the inner surface of the first hole portion extends along a circle, When viewed from the extending direction of the second hole portion, the inner surface of the second hole portion extends along a circle, The inner diameter of the second hole portion is larger than the inner diameter of the first hole portion.

2. The ferrule according to claim 1.

3. each of the plurality of fiber holes further includes a third hole portion located between the first hole portion and the second hole portion in the first direction; a pitch in the second direction of the third hole portions, each of which is the third hole portion, increases from the second hole portions toward the first hole portions; The ferrule according to claim 1 or 2.

4. the pitch of the plurality of first holes is equal to or greater than 235 μm and equal to or less than 265 μm, The pitch of the plurality of second hole portions is 150 μm or more and 180 μm or less.

4. The ferrule according to claim 3.

5. When viewed from the extending direction of the first hole portion, the inner surface of the first hole portion extends along a circle, When viewed from the extending direction of the second hole portion, the inner surface of the second hole portion extends along a circle, the inner diameter of the first hole portion is 110 μm or more and 140 μm or less; The inner diameter of the second hole portion is 185 μm or more and 215 μm or less.

4. The ferrule according to claim 3.

6. a first side surface and a second side surface positioned to sandwich the plurality of fiber holes in the second direction; When viewed from the first direction, a center of a first outermost hole portion, which is located closest to the first side surface among the plurality of first hole portions, is located closer to the first side surface than a center of a second outermost hole portion, which is located closest to the first side surface among the plurality of second hole portions, When viewed from the first direction, a center of a third outermost hole portion, which is located closest to the second side surface among the plurality of first hole portions, is located closer to the second side surface than a center of a fourth outermost hole portion, which is located closest to the second side surface among the plurality of second hole portions. The ferrule according to claim 1 or 2.

7. a portion of the inner surface of the first outermost hole portion closest to the first side surface and a portion of the inner surface of the second outermost hole portion closest to the first side surface are positioned on the same straight line, a portion of the inner surface of the third outermost hole portion closest to the second side surface and a portion of the inner surface of the fourth outermost hole portion closest to the second side surface are positioned on the same straight line; 7. The ferrule according to claim 6.

8. the pitch of the plurality of first holes is equal to or greater than 161 μm and equal to or less than 191 μm; The pitch of the plurality of second hole portions is 150 μm or more and 180 μm or less.

7. The ferrule according to claim 6.

9. When viewed from the extending direction of the first hole portion, the inner surface of the first hole portion extends along a circle, When viewed from the extending direction of the second hole portion, the inner surface of the second hole portion extends along a circle, the inner diameter of the first hole portion is 110 μm or more and 140 μm or less; The inner diameter of the second hole portion is 235 μm or more and 265 μm or less.

7. The ferrule according to claim 6.

10. The ferrule according to claim 1 or 2; a plurality of optical fibers; an end portion of each of the plurality of optical fibers is inserted into a corresponding one of the plurality of fiber holes; Optical connector.

11. Each of the plurality of optical fibers includes a glass fiber and a coating layer covering the outer periphery of the glass fiber, the outer diameter of the glass fiber is 110 μm or more and 140 μm or less; The outer diameter of the coating layer is 150 μm or more and 180 μm or less. The optical connector according to claim 10.

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