Ferrules and optical connectors

Abstract

This ferrule (30) comprises: a tip surface (32); an opening section (33a) provided on the opposite side to the tip surface (32) in a first direction crossing the tip surface (32); a plurality of fiber grooves (40) which extend in the first direction between the tip surface (32) and the opening section (33a), are arranged in a second direction crossing the first direction, and can support each of a plurality of optical fibers; and a plurality of lenses (31c) disposed on the respective extension lines of the plurality of fiber grooves (40). The fiber grooves (40) have: a first fiber groove section (41) for positioning the optical fibers with respect to the lenses (31c); and a second fiber groove section (42) for introducing the optical fibers into the first fiber groove section (41). The first fiber groove section (41) is disposed in the first direction to be closer to the lens (31c) than the second fiber groove section (42).

Description

[Technical Field]

[0001] The present disclosure relates to a ferrule and an optical connector. This application claims priority to Japanese Application No. 2020-161209, filed on September 25, 2020, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Conventionally, optical connectors have been known that include a ferrule having multiple lenses at its tip and multiple optical fibers inserted into the ferrule (see, for example, Patent Document 1). In such optical connectors, for example, multiple fiber grooves are provided at positions corresponding to the multiple lenses, each supporting one of the multiple optical fibers. When assembling the optical fiber into the ferrule, the optical fiber is inserted into the ferrule through an opening formed at the rear end of the ferrule, and the optical fiber is positioned in the fiber groove. By supporting the optical fiber in the fiber groove, the optical fiber can be positioned with high precision relative to the lens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-090974 Summary of the Invention

[0004] A ferrule according to an embodiment of the present disclosure includes a tip surface, an opening provided on the opposite side of the tip surface in a first direction intersecting the tip surface, a plurality of fiber grooves extending along the first direction between the tip surface and the opening, the fiber grooves being arranged along a second direction intersecting the first direction and capable of supporting a plurality of optical fibers, and a plurality of lenses respectively arranged on extension lines of the plurality of fiber grooves. The fiber grooves have a first fiber groove portion for positioning the optical fiber with respect to the lens and a second fiber groove portion for guiding the optical fiber into the first fiber groove portion. The first fiber groove portion is arranged closer to the lens than the second fiber groove portion in the first direction.

[0005] An optical connector according to an embodiment of the present disclosure includes the above-described ferrule and a plurality of optical fibers supported in a plurality of fiber grooves and arranged on the optical axes of a plurality of lenses, respectively. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing an optical connector according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the optical connector of FIG. [Figure 3] FIG. 3 is a perspective view showing a ferrule according to one embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing the ferrule of FIG. [Figure 5] FIG. 5 is an enlarged cross-sectional view of a portion of the ferrule of FIG. [Figure 6] FIG. 6 is another cross-sectional view of the ferrule of FIG. [Figure 7A] FIG. 7A is a cross-sectional view showing a straight portion of a first fiber groove portion. [Figure 7B] FIG. 7B is a cross-sectional view showing the straight portion of the second fiber groove portion. [Figure 8] FIG. 8 is a cross-sectional view showing the tapered portion of the second fiber groove section. [Figure 9A]FIG. 9A is a cross-sectional view showing a modified example of the shape of the second fiber groove portion. [Figure 9B] FIG. 9B is a cross-sectional view showing another modified example of the shape of the second fiber groove portion. [Figure 9C] FIG. 9C is a cross-sectional view showing another modified example of the shape of the second fiber groove portion. [Figure 10] FIG. 10 is a perspective view showing an optical connection structure including an optical connector. [Figure 11] FIG. 11 is a plan view showing the optical connection structure of FIG. [Figure 12] FIG. 12 is a rear view showing the optical connection structure of FIG. [Figure 13] FIG. 13 is a rear view showing a modified example of the adapter of the optical connection structure. [Figure 14] FIG. 14 is a diagram showing how an optical connector is inserted into the adapter of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] [Problem to be solved by this disclosure] In the optical connector described in Patent Document 1, if it is difficult to visually observe the fiber groove from the opening at the rear end of the ferrule, it may be difficult to reliably position the optical fiber inserted into the ferrule in the fiber groove when assembling the optical fiber to the ferrule. In such a case, there is a risk that the optical fiber inserted into the ferrule may collide with the wall between the fiber grooves, which may cause problems in the workability when assembling the optical fiber to the ferrule.

[0008] [Effects of this disclosure] The ferrule and optical connector according to the present disclosure can improve the workability when assembling an optical fiber.

[0009] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. A ferrule according to one embodiment of the present disclosure includes a tip surface, an opening provided on the opposite side of the tip surface in a first direction intersecting the tip surface, and a plurality of fiber grooves extending along the first direction between the tip surface and the opening, arranged along a second direction intersecting the first direction, each capable of supporting a plurality of optical fibers, and a plurality of lenses respectively arranged on extension lines of the plurality of fiber grooves. The fiber grooves have a first fiber groove portion for positioning the optical fiber with respect to the lens and a second fiber groove portion for guiding the optical fiber into the first fiber groove portion. The first fiber groove portion is arranged closer to the lens than the second fiber groove portion in the first direction.

[0010] The fiber groove of this ferrule has a first fiber groove portion for positioning the optical fiber relative to the lens, and a second fiber groove portion for guiding the optical fiber into the first fiber groove portion. The first fiber groove portion is positioned closer to the lens than the second fiber groove portion in the first direction. Therefore, when the optical fiber is inserted into the ferrule from the opening, the optical fiber is guided into the first fiber groove portion by the second fiber groove portion, and the first fiber groove portion positions the optical fiber relative to the lens. In this way, the presence of the second fiber groove portion for guiding the optical fiber into the first fiber groove portion reduces the risk of the optical fiber colliding with the wall between the fiber grooves when inserting the optical fiber into the ferrule, and the optical fiber can be reliably positioned in the first fiber groove portion. Therefore, the above-described ferrule can improve the workability when assembling an optical fiber.

[0011] In a cross section perpendicular to the first direction, each of the first fiber groove and the second fiber groove may have a V-shape, which allows for more accurate positioning of the optical fiber relative to the lens.

[0012] In a cross section perpendicular to the first direction, the opening width of the second fiber groove portion may be larger than the opening width of the first fiber groove portion. In this case, the allowable amount of misalignment of the optical fiber supported in the second fiber groove portion relative to the lens can be ensured to be larger than the allowable amount of misalignment of the optical fiber supported in the first fiber groove portion relative to the lens. As a result, when inserting the optical fiber into the ferrule, the approximate position of the optical fiber relative to the lens can be determined in the second fiber groove portion, and then the position of the optical fiber relative to the lens can be determined with high precision in the first fiber groove portion.

[0013] In a cross section perpendicular to the first direction, the diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the second fiber groove portion may be larger than the diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the first fiber groove portion. In this case, the allowable amount of misalignment of the optical fiber with respect to the lens when supported in the second fiber groove portion can be ensured to be larger than the allowable amount of misalignment of the optical fiber with respect to the lens when supported in the first fiber groove portion. This makes it possible, when inserting the optical fiber into the ferrule, to determine the approximate position of the optical fiber with respect to the lens in the second fiber groove portion, and then to determine the position of the optical fiber with respect to the lens with high precision in the first fiber groove portion.

[0014] The second fiber groove portion may include, at each position along the first direction, a straight portion in which the diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the second fiber groove portion is constant, and a tapered portion located on the opposite side of the first fiber groove portion from the straight portion in the first direction, which slopes so that the diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the second fiber groove portion increases with increasing distance from the straight portion. The presence of such a tapered portion allows the optical fiber inserted into the ferrule from the opening to be reliably guided into the straight portion. Furthermore, the presence of the straight portion allows the orientation of the optical fiber to be stabilized along the first direction, allowing the optical fiber to be smoothly introduced into the first fiber groove portion while maintaining the stable orientation. Therefore, the above-described configuration allows the optical fiber to be reliably and smoothly introduced into the first fiber groove portion.

[0015] The total length of the second fiber groove portion in the first direction may be equal to or greater than the total length of the first fiber groove portion in the first direction, in which case the attitude of the optical fiber in the second fiber groove portion can be more reliably stabilized.

[0016] The second fiber groove portion may be spaced a predetermined distance from the first fiber groove portion in the first direction, and in this case, the first fiber groove portion can be fabricated with high accuracy by forming the first fiber groove portion separately from the second fiber groove portion.

[0017] The ferrule may further include an upper surface disposed at a position facing the plurality of fiber grooves in a third direction intersecting the first and second directions. The upper surface may have a window opening in a region facing the first fiber groove portion in the third direction. When viewed from the third direction, the first fiber groove portion may be located inside the window. In this case, the window can be used not only as an injection window for injecting adhesive into the interior of the ferrule, but also for aligning the optical fiber when introducing it into the first fiber groove portion. This further improves the workability when assembling the optical fiber.

[0018] The above-described ferrule may further include a pair of side surfaces arranged opposite each other across the plurality of fiber grooves in the second direction. Each of the pair of side surfaces may be provided with a guide portion that guides insertion into the adapter along the first direction. In this case, the guide portions provided on each of the pair of side surfaces can be used to position the ferrule relative to the adapter. This allows the ferrule to be positioned relative to the adapter without using expensive guide pins.

[0019] An optical connector according to an embodiment of the present disclosure includes any of the ferrules described above and a plurality of optical fibers supported in a plurality of fiber grooves and arranged on the optical axes of a plurality of lenses, respectively. Because this optical connector includes any of the ferrules described above, as described above, the workability of assembling the optical fibers to the ferrules can be improved.

[0020] In the optical connector described above, the optical fiber may be fixed in the first fiber groove portion with an adhesive. In this case, the position of the optical fiber relative to the lens is fixed by the adhesive, so that the positioning of the optical fiber relative to the lens can be more reliably performed.

[0021] In the optical connector described above, the ferrule may have an upper surface arranged at a position facing the plurality of fiber grooves in a third direction intersecting the first and second directions, and the upper surface may have a window opening in a region facing the first fiber groove portion in the third direction. A lid may be provided inside the window and placed over the first fiber groove portion via the optical fiber. In this case, the lid presses the optical fiber against the first fiber groove portion, thereby more reliably positioning the optical fiber with respect to the lens.

[0022] [Details of the embodiments of the present disclosure] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0023] FIG. 1 is a perspective view showing an optical connector 10 according to this embodiment. FIG. 2 is a cross-sectional view showing the optical connector 10. For ease of understanding, each drawing shows an XYZ Cartesian coordinate system. In this embodiment, the longitudinal direction of the optical connector 10 is defined as the X direction (first direction), the lateral direction of the optical connector 10 is defined as the Y direction (second direction), and the height direction of the optical connector 10 is defined as the Z direction (third direction). In the following description, for convenience of explanation, directions may be defined as "front" and "rear." Within the X direction, the direction from the optical connector 10 toward the mating optical connector 10 (see FIG. 10) is defined as "front," and the opposite direction is defined as "rear."

[0024] As shown in FIGS. 1 and 2, the optical connector 10 includes a plurality of (12 in this embodiment) optical fibers 20 and a ferrule 30 into which the front ends of the optical fibers 20 are inserted. Each optical fiber 20 extends along the X direction and is arranged in a row along the Y direction. Each optical fiber 20 is a multi-mode optical fiber (MMF). It may be a single-mode optical fiber (SMF). The number of optical fibers 20 is not limited to 12, and may be other numbers such as 4, 8, or 16.

[0025] The ferrule 30 holds a plurality of optical fibers 20. The ferrule 30 has, for example, a substantially rectangular parallelepiped appearance. The ferrule 30 has a lens portion 31 at its front end. The ferrule 30 is, for example, configured integrally with the lens portion 31. That is, the ferrule 30 is formed by integral molding with the lens portion 31. Therefore, the ferrule 30 is configured from the same material as the lens portion 31, i.e., an optically transparent material capable of configuring the lens portion 31. The ferrule 30 can be configured from, for example, PPS (polyphenylene sulfide), PEI (polyetherimide), PC (polycarbonate), PMMA (polymethyl methacrylate), PES (polyethersulfone), COP (cycloolefin polymer), or the like.

[0026] The lens portion 31 is provided in front of the plurality of optical fibers 20 and faces the plurality of optical fibers 20 in the X direction. The lens portion 31 has, for example, a plate shape along the YZ plane. The lens portion 31 includes a front end face 31a located at the front end in the X direction, a rear end face 31b located at the rear end in the X direction, and a plurality of lenses 31c provided on the front end face 31a. The front end face 31a and the rear end face 31b are, for example, planes parallel to the YZ plane. The rear end face 31b faces the plurality of optical fibers 20 in the X direction.

[0027] Each lens 31c is a convex lens that protrudes forward from the front end face 31a. The lenses 31c are arranged in a row along the Y direction to correspond to the position of each optical fiber 20. Each lens 31c is disposed on the optical axis of each optical fiber 20 and is optically coupled to each optical fiber 20. For example, when viewed from the X direction, the optical axis of each lens 31c coincides with the optical axis of each optical fiber 20. Light emitted from each optical fiber 20 is converted into parallel light (i.e., collimated light) by each lens 31c and then enters the optical connector 10 (see FIG. 10 ) to be connected. In order to suppress light reflected back to the front end face of the optical fiber 20, the optical axis of the optical fiber 20 and the optical axis of the lens 31c may be misaligned with each other. Similarly, in order to suppress light reflected back, the front end face of the optical fiber 20 or the front end face 31a of the lens portion 31 may be inclined, for example, by 8° with respect to the YZ plane.

[0028] The ferrule 30 has a front end face 32 (tip face) located at the front end in the X direction, a rear end face 33 located at the rear end in the X direction, and four outer surfaces 34, 35, 36, and 37 connecting the front end face 32 and the rear end face 33 in the X direction. The front end face 32 and the rear end face 33 are, for example, along the YZ plane. The front end face 32 is located in a position that protrudes slightly forward from the front end face 31a of the lens portion 31. The rear end face 33 includes an opening 33a (see FIG. 2) that collectively receives multiple optical fibers 20. The opening 33a is a portion of the rear end face 33 that opens in the X direction.

[0029] The outer surface 34 and the outer surface 35 face each other in the Z direction and extend along the XY plane. The outer surface 34 faces one side in the Z direction and constitutes the upper surface of the ferrule 30. The outer surface 35 faces the other side in the Z direction and constitutes the lower surface of the ferrule 30. The outer surface 34 is located opposite a plurality of fiber grooves 40 (described later) in the Z direction. The outer surface 34 is provided with two windows 34a and 34b that open in the Z direction. The window 34a is located closer to the front end face 32 than the window 34b in the X direction. The window 34a is located, for example, behind the lens portion 31. The width of the window 34a in the Y direction is the same as or wider than the overall width of the plurality of optical fibers 20 in the Y direction. The window 34b is located at a predetermined distance rearward of the window 34a. The width of the window portion 34b in the Y direction is, for example, narrower than the width of the window portion 34a in the Y direction. The number of windows opening in the outer surface 34 is not limited to two, and may be one, or three or more.

[0030] The outer surface 36 and the outer surface 37 are positioned opposite each other in the Y direction and constitute a pair of side surfaces of the ferrule 30. The outer surface 36 and the outer surface 37 are respectively provided with V-grooves 36a and V-grooves 37a (guide portions) for guiding the insertion of the ferrule 30 into an adapter 50 (see FIG. 10 ), which will be described later. The V-grooves 36a and V-grooves 37a are, for example, positioned symmetrically with respect to the center of the ferrule 30 in the Y direction. The V-groove 36a is recessed from the outer surface 36 toward the inside of the ferrule 30 in the Y direction (i.e., toward the side from the outer surface 36 toward the outer surface 37), and opens to the outside of the ferrule 30 in the Y direction (i.e., on the side opposite the outer surface 37 from the outer surface 36). The V-groove 36a has a V-shape in a YZ cross section, and the bottom of the V-groove 36a is, for example, rounded. The V-groove 36a extends linearly along the X direction on the outer surface 36. For example, the V-groove 36a extends continuously along the X direction on the outer surface 36 from the front end face 32 to the rear end face 33. That is, the V-groove 36a extends over the entire length of the ferrule 30 in the X direction.

[0031] The V-groove 37a is recessed from the outer surface 37 toward the inside of the ferrule 30 in the Y direction and opens to the outside of the ferrule 30 in the Y direction. The V-groove 37a has, for example, the same shape as the V-groove 36a. The V-groove 37a extends linearly along the X-direction on the outer surface 37. For example, the V-groove 37a extends continuously along the X-direction from the front end face 32 to the rear end face 33 on the outer surface 37. In other words, the V-groove 37a extends over the entire length of the ferrule 30 in the X-direction.

[0032] As shown in FIG. 2 , the ferrule 30 has an accommodating hole 39 for accommodating the optical fibers 20 received through the opening 33a of the rear end face 33, and a plurality of fiber grooves 40 for supporting the optical fibers 20 accommodated in the accommodating hole 39. The accommodating hole 39 extends in the X direction from the opening 33a of the rear end face 33 to the rear end face 31b of the lens portion 31. The accommodating hole 39 communicates in the Z direction with the window portions 34a and 34b provided in the outer surface 34. The plurality of fiber grooves 40 extend in the X direction from the center of the accommodating hole 39 in the X direction to the front end of the accommodating hole 39. The front ends of the plurality of fiber grooves 40 are positioned opposite the window portion 34a in the Z direction. The rear ends of the plurality of fiber grooves 40 are positioned rearward of the window portion 34b. The plurality of fiber grooves 40 are arranged in the Y direction to correspond to the plurality of lenses 31c, respectively. That is, the lenses 31c are arranged on the extension lines of the fiber grooves 40. Therefore, the lenses 31c face the optical fibers 20 supported in the fiber grooves 40 in the X direction.

[0033] As shown in FIG. 2, adhesive A is applied to the fiber grooves 40 through the window 34a. The adhesive A is made of, for example, a light-transmitting material. Each optical fiber 20 is fixed to each fiber groove 40 by the adhesive A. Furthermore, a lid B is provided inside the window 34a above each fiber groove 40. The lid B is a plate-shaped member along the XY plane and is configured separately from the ferrule 30. The lid B is made of, for example, a light-transmitting glass plate or resin. The lid B is placed on each optical fiber 20 supported in each fiber groove 40 and is positioned so as to press each optical fiber 20 against the fiber groove 40. This fixes the position of each optical fiber 20 relative to each fiber groove 40. The lid B is, for example, positioned in a region inside the window 34a that faces a straight portion 41b (see FIG. 5) of a first fiber groove 41 (described later) in the Z direction and is in contact with the straight portion 41b. 2, the lid portion B is arranged to fit inside the window portion 34a, but a portion of the lid portion B may protrude outward from the window portion 34a in the Z direction. In other words, a portion of the lid portion B may protrude upward from the window portion 34a. The adhesive A may penetrate into the gaps between the lid portion B and each fiber groove 40, or may penetrate into the interior of each fiber groove 40 (i.e., the gaps between each optical fiber 20 and each fiber groove 40).

[0034] FIG. 3 is a perspective view showing the ferrule 30. FIG. 4 is a cross-sectional view showing the ferrule 30. FIG. 4 shows an XZ cross section of the ferrule 30. As shown in FIG. 4, the fiber groove 40 includes, in order from the lens portion 31 side in the X direction, a first fiber groove portion 41 and a second fiber groove portion 42. The first fiber groove portion 41 is disposed behind the lens portion 31. The second fiber groove portion 42 is disposed further behind the first fiber groove portion 41. Therefore, the first fiber groove portion 41 is disposed closer to the lens portion 31 in the X direction than the second fiber groove portion 42. In other words, the second fiber groove portion 42 is disposed on the opposite side of the first fiber groove portion 41 from the lens portion 31 in the X direction.

[0035] Each of the first fiber groove 41 and the second fiber groove 42 is, for example, a V-groove. That is, each of the first fiber groove 41 and the second fiber groove 42 has a V-shape that opens upward (i.e., in the Z direction from the outer surface 35 to the outer surface 34) in the YZ cross section. The first fiber groove 41 is provided to position the optical fiber 20 with respect to the lens 31c with high precision. Therefore, the first fiber groove 41 is formed with high precision so that the optical axis of the optical fiber 20 supported in the first fiber groove 41 coincides with or is very close to the optical axis of the lens 31c when viewed from the X direction. The optical fiber 20 supported in the first fiber groove 41 is aligned with high precision with respect to the lens 31c.

[0036] On the other hand, the second fiber groove 42 is provided for guiding the optical fiber 20 into the first fiber groove 41. The second fiber groove 42 determines the approximate position of the optical fiber 20 relative to the lens 31c so that the optical fiber 20 inserted into the ferrule 30 from the opening 33a can be easily introduced into the first fiber groove 41. In other words, the second fiber groove 42 roughly positions the optical fiber 20 relative to the lens 31c before accurately positioning the optical fiber 20 in the first fiber groove 41. Therefore, when the optical fiber 20 is supported in the second fiber groove 42, a larger tolerance for misalignment of the optical axis of the optical fiber 20 relative to the optical axis of the lens 31c is ensured compared to when the optical fiber 20 is supported in the first fiber groove 41. Therefore, before reaching the first fiber groove 41, the optical fiber 20 supported in the second fiber groove 42 is roughly positioned relative to the lens 31c.

[0037] Here, the configurations of the first fiber groove portion 41 and the second fiber groove portion 42 will be described in more detail. Fig. 5 is an enlarged cross-sectional view showing the vicinity of the first fiber groove portion 41 and the second fiber groove portion 42 in Fig. 4. Fig. 6 is another cross-sectional view showing the vicinity of the first fiber groove portion 41 and the second fiber groove portion 42. Fig. 5 shows an XZ cross-section of the ferrule 30. Fig. 6 shows an XY cross-section of the ferrule 30.

[0038] As shown in Fig. 5, the first fiber groove portions 41 are formed at positions facing the window portions 34a in the Z direction. When viewed from the Z direction, the first fiber groove portions 41 are contained within the window portions 34a and are not present outside the window portions 34a. The total length L1 of the first fiber groove portions 41 in the X direction is shorter than the width of the window portions 34a in the X direction and longer than the width in the X direction of the lid portion B (see Fig. 2) disposed inside the window portions 34a. The total width of all the first fiber groove portions 41 in the Y direction is smaller than the width of the window portions 34a in the Y direction.

[0039] The total length L1 of the first fiber groove portion 41 is set, for example, in the range of 3 to 40 times the diameter of the optical fiber 20. Here, the diameter of the optical fiber 20 means 0.125 mm, which is the diameter of a general-purpose optical fiber. In this way, by making the total length L1 of the first fiber groove portion 41 larger than the diameter of the optical fiber 20, it is possible to easily stabilize the posture of the optical fiber 20 supported by the first fiber groove portion 41 along the X direction. The total length L1 of the first fiber groove portion 41 means the length in the X direction of the entire first fiber groove portion 41, including the tapered portion 41a, the straight portion 41b, and the tapered portion 41c, which will be described later.

[0040] On the other hand, the second fiber groove portion 42 is not formed at a position facing the window portion 34a in the Z direction. The second fiber groove portion 42 is arranged rearward in the X direction from the window portion 34a and the first fiber groove portion 41 at a predetermined distance. As shown in FIGS. 5 and 6, the second fiber groove portion 42 is arranged rearward from the first fiber groove portion 41 by a distance R in the X direction. The distance R is set, for example, in the range of 0.01 mm to 3 mm. The second fiber groove portion 42 is formed at a position facing the window portion 34b rearward of the window portion 34a in the Z direction.

[0041] The window portion 34b is provided, for example, at a position facing in the Z direction with respect to the center portion of the second fiber groove portion 42 in the X direction. The overall length L2 of the second fiber groove portion 42 in the X direction is longer than the width of the window portion 34b in the X direction. The overall length L2 of the second fiber groove portion 42 in the X direction is set to be equal to or longer than the overall length L1 of the first fiber groove portion 41 in the X direction. In other words, the overall length L2 of the second fiber groove portion 42 is the same as or longer than the overall length L1 of the first fiber groove portion 41. The overall length L2 of the second fiber groove portion 42 means the length in the X direction of the entire second fiber groove portion 42, including a straight portion 42a and a tapered portion 42b, which will be described later.

[0042] 5 and 6, the first fiber groove portion 41 includes, in order from the lens portion 31 side in the X direction, a tapered portion 41a (second tapered portion), a straight portion 41b, and a tapered portion 41c (first tapered portion). The straight portion 41b is a portion that extends linearly along the X direction behind the lens portion 31. In the straight portion 41b, the YZ cross-sectional shape of the first fiber groove portion 41 (i.e., the opening shape of the V-groove) is constant at each position along the X direction. The straight portion 41b is formed so as to position the optical fiber 20 with respect to the lens 31c with high precision.

[0043] FIG. 7A is a cross-sectional view showing the straight portion 41b of the first fiber groove portion 41. FIG. 7A shows an imaginary circle C1 inscribed in a pair of inner surfaces S1, S1 constituting the straight portion 41b. The center C0 of the imaginary circle C1 coincides with the optical axis of the lens 31c (see FIGS. 5 and 6) when viewed from the X direction, and the diameter d1 of the imaginary circle C1 is the same as the diameter of the optical fiber 20 (see FIGS. 1 and 2). The optical axis of the optical fiber 20 supported by the straight portion 41b coincides with the optical axis of the lens 31c when viewed from the X direction. Therefore, in FIG. 7A, the two-dot chain line indicating the imaginary circle C1 can be said to represent the outer shape of the optical fiber 20 supported by the straight portion 41b. The center C0 of the imaginary circle C1 does not need to strictly coincide with the optical axis of the lens 31c when viewed from the X direction, and may be slightly deviated from the optical axis of the lens 31c.

[0044] As described above, the shape of the straight portion 41b is designed so that the optical axis of the optical fiber 20 supported by the straight portion 41b coincides with or is extremely close to the optical axis of the lens 31c. This allows the optical fiber 20 to be positioned with high precision in the straight portion 41b. Therefore, when the optical fiber 20 is supported by the straight portion 41b, the optical fiber 20 is aligned with high precision relative to the lens 31c. In the straight portion 41b, the YZ cross-sectional shape of the first fiber groove portion 41 is constant at each position along the X direction, and therefore the diameter d1 of the imaginary circle C1 is also constant at each position along the X direction. In this case, the opening width W1 and depth D1 of the first fiber groove portion 41, which is a V-shaped groove, are also constant at each position along the X direction of the straight portion 41b. The opening width W1 of the first fiber groove portion 41 is the maximum width of the opening portion of the first fiber groove portion 41 in the Y direction. More specifically, the opening width W1 of the first fiber groove 41 is the width in the Y direction of the opening of the first fiber groove 41 on the forming surface where the first fiber groove 41 is formed. The depth D1 of the first fiber groove 41 is the distance in the Z direction from the forming surface of the first fiber groove 41 to the bottom of the first fiber groove 41.

[0045] As shown in FIGS. 5 and 6, the tapered portion 41a of the first fiber groove portion 41 is located in front of the straight portion 41b. Specifically, the tapered portion 41a extends in the X direction from the front end of the straight portion 41b to a position just before the lens portion 31 (i.e., a position slightly spaced rearward from the rear end face 31b of the lens portion 31). Therefore, the tapered portion 41a is located between the lens portion 31 and the straight portion 41b in the X direction. In the tapered portion 41a, the YZ cross-sectional shape of the first fiber groove portion 41 changes at each position along the X direction. The tapered portion 41a is inclined so that the diameter d1 (see FIG. 7A) of the imaginary circle C1 increases with increasing distance from the straight portion 41b in the X direction. The inclination of the tapered portion 41a may be linear or curved in the XZ cross section shown in FIG. 5.

[0046] As a result, the diameter d1 of the imaginary circle C1 at the rear end of the tapered portion 41a is the same as the diameter d1 of the imaginary circle C1 at the straight portion 41b, and the diameter d1 of the imaginary circle C1 at the front end of the tapered portion 41a is larger than the diameter d1 of the imaginary circle C1 at the straight portion 41b. For example, in the tapered portion 41a, the opening width W1 of the first fiber groove portion 41 is constant at each position along the X direction, while the depth D1 of the first fiber groove portion 41 becomes deeper with increasing distance from the straight portion 41b in the X direction (see FIG. 7A). The presence of such a tapered portion 41a makes it possible to ensure a space in front of the straight portion 41b to accommodate the adhesive A (see FIG. 2).

[0047] As shown in FIGS. 5 and 6, the tapered portion 41c of the first fiber groove portion 41 extends further rearward from the rear end of the straight portion 41b. The tapered portion 41c is disposed between the straight portion 41b and the second fiber groove portion 42 in the X direction. In the tapered portion 41c, the YZ cross-sectional shape of the first fiber groove portion 41 changes at each position along the X direction. The tapered portion 41c is inclined so that the diameter d1 (see FIG. 7A) of the imaginary circle C1 increases with increasing distance from the straight portion 41b in the X direction. The inclination of the tapered portion 41c may be linear or curved in the XZ cross section shown in FIG. 5.

[0048] As a result, the diameter d1 of the imaginary circle C1 at the front end of the tapered portion 41c is the same as the diameter d1 of the imaginary circle C1 in the straight portion 41b, and the diameter d1 of the imaginary circle C1 at the rear end of the tapered portion 41c is larger than the diameter d1 of the imaginary circle C1 in the straight portion 41b. Therefore, among the diameters d1 of the imaginary circle C1 at each position along the X direction of the first fiber groove portion 41, the diameter d1 of the imaginary circle C1 in the straight portion 41b is the smallest.

[0049] For example, in the tapered portion 41c, the opening width W1 of the first fiber groove portion 41 is constant at each position along the X direction, while the depth D1 of the first fiber groove portion 41 increases with increasing distance from the straight portion 41b in the X direction (see FIG. 7A). The presence of such tapered portion 41c makes it possible to guide the optical fiber 20 from the second fiber groove portion 42 into the straight portion 41b of the first fiber groove portion 41. Therefore, the tapered portion 41c functions as a guide portion that guides the optical fiber 20 from the second fiber groove portion 42 to the straight portion 41b.

[0050] 5 and 6, the second fiber groove portion 42 includes, in order from the first fiber groove portion 41 side in the X direction, a straight portion 42a and a tapered portion 42b. The straight portion 42a is a portion that extends linearly along the X direction behind the first fiber groove portion 41. The straight portion 42a extends rearward from a position that is a distance R away from the rear end of the tapered portion 41c of the first fiber groove portion 41. The tapered portion 42b extends further rearward from the rear end of the straight portion 42a. Therefore, the tapered portion 42b is located on the opposite side of the straight portion 42a from the first fiber groove portion 41 in the X direction. A window portion 34b is located at a position facing the connection portion between the straight portion 42a and the tapered portion 42b in the Z direction.

[0051] In the straight portion 42a, the YZ cross-sectional shape of the second fiber groove portion 42 (i.e., the opening shape of the V-groove) is constant at each position along the X direction. The straight portion 42a is formed to determine the approximate position of the optical fiber 20 relative to the lens 31c. Therefore, the optical fiber 20 supported by the straight portion 42a is roughly positioned relative to the lens 31c.

[0052] FIG. 7B is a cross-sectional view showing the straight portion 42a of the second fiber groove portion 42. In addition to the imaginary circle C1 shown in FIG. 7A, FIG. 7B also shows an imaginary circle C2 inscribed in a pair of inner surfaces S2, S2 constituting the straight portion 42a. The imaginary circle C2 is concentric with the center C0 of the imaginary circle C1 (i.e., the optical axis of the lens 31c) and has a diameter d2 larger than that of the imaginary circle C1. Therefore, the allowable amount of misalignment of the optical fiber 20 supported by the straight portion 42a of the second fiber groove portion 42 relative to the lens 31c is ensured to be greater than the allowable amount of misalignment of the optical fiber 20 supported by the straight portion 41b of the first fiber groove portion 41 relative to the lens 31c. Thus, the shape of the straight portion 42a is formed to roughly position the optical fiber 20 relative to the lens 31c.

[0053] In the straight portion 42a, the YZ cross-sectional shape of the second fiber groove portion 42 is constant at each position along the X direction, and therefore the diameter d2 of the imaginary circle C2 is also constant at each position along the X direction. In this case, the opening width W2 and depth D2 of the second fiber groove portion 42, which is a V-shaped groove, are also constant at each position along the X direction of the straight portion 42a. The opening width W2 of the second fiber groove portion 42 is the maximum width in the Y direction of the opening portion of the second fiber groove portion 42. More specifically, the opening width W2 of the second fiber groove portion 42 is the width in the Y direction of the opening portion of the second fiber groove portion 42 at the forming surface where the second fiber groove portion 42 is formed. The depth D2 of the second fiber groove portion 42 is the distance in the Z direction from the forming surface of the second fiber groove portion 42 to the bottom of the second fiber groove portion 42. The diameter d2 of the imaginary circle C2 is greater than the diameter d1 of the imaginary circle C1. Therefore, the opening width W2 of the straight portion 42a is larger than the opening width W1 of the straight portion 41b, and the depth D2 of the straight portion 42a is deeper than the depth D1 of the straight portion 41b.

[0054] FIG. 8 is a cross-sectional view showing the tapered portion 42b of the second fiber groove portion 42. In FIG. 8, along with the virtual circle C2 shown in FIG. 7B, a virtual circle C3 inscribed in a pair of inner surfaces S3, S3 constituting the tapered portion 42b is shown. The virtual circle C3 is a concentric circle having a diameter d3 larger than that of the virtual circle C2, centered on the center C0 of the virtual circle C1 (i.e., the optical axis of the lens 31c). In the tapered portion 42b, the YZ cross-sectional shape of the second fiber groove portion 42 changes at each position along the X direction. The tapered portion 42b is inclined such that the diameter d3 of the virtual circle C3 increases with increasing distance from the straight portion 42a in the X direction. The inclination of the tapered portion 42b may be linear or curved in the XZ cross section shown in FIG. 5.

[0055] As a result, the diameter d3 of the imaginary circle C3 at the rear end of the tapered portion 42b is larger than the diameter d2 of the imaginary circle C2 in the straight portion 42a. The diameter d3 of the imaginary circle C3 at the front end of the tapered portion 42b is the same as the diameter d2 of the imaginary circle C2 in the straight portion 42a. Therefore, among the imaginary circles C2 and C3 at each position along the X direction of the second fiber groove portion 42, the diameter d2 of the imaginary circle C2 in the straight portion 42a is the smallest. The diameter d1 of the imaginary circle C1 in the straight portion 41b of the first fiber groove portion 41 is smaller than the diameter d2 of the imaginary circle C2 in the straight portion 42a of the second fiber groove portion 42.

[0056] For example, in the tapered portion 42b, the opening width W2 of the second fiber groove portion 42 is constant at each position along the X direction, while the depth D3 of the second fiber groove portion 42 increases with increasing distance from the straight portion 42a in the X direction (see FIG. 8). The existence of such tapered portion 42b makes it possible to guide the optical fiber 20 inserted through the opening 33a into the straight portion 42a. Therefore, the tapered portion 42b functions as a guide that guides the optical fiber 20 into the straight portion 42a.

[0057] When manufacturing the optical connector 10 described above, first, multiple optical fibers 20 are inserted into the receiving hole 39 inside the ferrule 30 through the opening 33a of the rear end face 33 of the ferrule 30. Then, each optical fiber 20 inserted into the receiving hole 39 is placed in each fiber groove 40. At this time, the optical fiber 20 is guided to the straight portion 42a by the tapered portion 42b of the second fiber groove portion 42. In the straight portion 42a, the optical fiber 20 is corrected to a state along the X direction and its approximate position relative to the lens 31c is determined. In this manner, the optical fiber 20 is roughly positioned in the second fiber groove portion 42.

[0058] The optical fiber 20 is then introduced from the straight portion 42a of the second fiber groove portion 42 into the tapered portion 41c of the first fiber groove portion 41. The optical fiber 20 is then guided from the tapered portion 41c to the straight portion 41b. In the straight portion 41b, the optical fiber 20 is straightened to a state along the X direction, and its precise position relative to the lens 31c is determined. In this manner, the optical fiber 20 is positioned with high precision in the first fiber groove portion 41. That is, the optical fiber 20 is positioned so that the optical axis of the optical fiber 20 supported by the straight portion 41b coincides with or is very close to the optical axis of the lens 31c, as viewed from the X direction. The optical fiber 20 is then transferred from the straight portion 41b to the tapered portion 41a and abuts against the rear end face 31b of the lens portion 31. The optical fiber 20 may be spaced apart from the rear end face 31b of the lens portion 31. That is, the optical fiber 20 may be positioned at a predetermined distance from the rear end face 31b of the lens portion 31.

[0059] Thereafter, adhesive A is injected into the interior of the ferrule 30 through the window portion 34a, and the lid portion B is placed inside the window portion 34a (see FIG. 2). At this time, the adhesive A injected into the interior of the ferrule 30 also spreads into the gaps between the lid portion B and each optical fiber 20. With the lid portion B pressing each optical fiber 20 against each fiber groove 40, the adhesive A hardens, thereby fixing each optical fiber 20 to each fiber groove 40. This fixes the position of each optical fiber 20 relative to the ferrule 30.

[0060] The configurations of the first fiber groove portion 41 and the second fiber groove portion 42 are not limited to those described above and can be modified as appropriate. For example, the second fiber groove portion 42 may be a groove having a different shape from the first fiber groove portion 41. In other words, the second fiber groove portion 42 is not limited to a V-groove having a V-shape in the YZ cross section, but may be a groove having another shape. Figures 9A, 9B, and 9C are cross-sectional views showing modified shapes of the second fiber groove portion 42.

[0061] As shown in FIG. 9A, the second fiber groove 42A may be a semicircular groove having a semicircular shape in the YZ cross section. As shown in FIG. 9B, the second fiber groove 42B may be a rectangular groove having a rectangular shape in the YZ cross section. As shown in FIG. 9C, the second fiber groove 42C may be a U-groove having a U-shape in the YZ cross section. The first fiber groove 41 does not necessarily have to be a V-groove, and may have another shape. The second fiber groove 42 does not necessarily have to be separated from the first fiber groove 41 in the X direction, and may be directly connected to the first fiber groove 41 in the X direction.

[0062] The second fiber groove 42 may not include the tapered portion 42b and may include only the straight portion 42a. The second fiber groove 42 may not include the straight portion 42a and may include only the tapered portion 42b. The first fiber groove 41 may not include the tapered portion 41a and the tapered portion 41c and may include only the straight portion 41b. The total length L2 of the second fiber groove 42 may be shorter than the total length L1 of the first fiber groove 41.

[0063] Next, an optical connection structure 1 including the optical connector 10 described above will be described with reference to Fig. 10, Fig. 11, and Fig. 12. Fig. 10 is a perspective view showing the optical connection structure 1. Fig. 11 is a plan view showing the optical connection structure 1. Fig. 12 is a rear view showing the optical connection structure 1. Figs. 10, 11, and 12 show the optical connector 10 in a state where the multiple optical fibers 20 are omitted (i.e., a state where only the ferrule 30 is shown). Figs. 10 and 11 show a cross section when the adapter 50 of the optical connection structure 1 is cut in the XY plane.

[0064] 10 and 11, the optical connection structure 1 includes a pair of optical connectors 10, 10 arranged to face each other in the X direction, and an adapter 50 into which the pair of optical connectors 10, 10 are inserted. The pair of optical connectors 10, 10 are arranged upside down relative to each other. The pair of optical connectors 10, 10 are fitted into the adapter 50 so that the respective ferrules 30, 30 face each other inside the adapter 50. Inside the adapter 50, the pair of ferrules 30, 30 may be in contact with each other by butting against each other, or may be arranged with a predetermined distance between them.

[0065] The adapter 50 is made of an elastic material such as PEI (polyetherimide), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), PC (polycarbonate), PMMA (polymethyl methacrylate), PES (polyethersulfone), or PA (polyamide). From the viewpoint of reducing the difference in the linear expansion coefficient between the material of the adapter 50 and the material of the ferrule 30, the material of the adapter 50 may be the same as that of the ferrule 30.

[0066] The adapter 50 has a cylindrical shape capable of accommodating the pair of ferrules 30, 30, and extends along the X direction. In the X direction, the overall length of the adapter 50 is longer than, for example, the combined length of the pair of ferrules 30, 30 when connected to each other. As shown in FIG. 12 , the adapter 50 has a rectangular cylindrical shape when viewed from the X direction. The adapter 50 has an insertion hole 51 that forms the interior of the rectangular cylindrical shape. The insertion hole 51 is a through-hole that penetrates the adapter 50 in the X direction. The insertion hole 51 has a rectangular shape when viewed from the X direction, and is composed of four inner surfaces 52, 53, 54, and 55.

[0067] The inner surface 52 faces the outer surface 34 of the ferrule 30 in the Z direction, and the inner surface 53 faces the outer surface 35 of the ferrule 30 in the Z direction. The inner surface 54 faces the outer surface 36 of the ferrule 30 in the Y direction, and the inner surface 55 faces the outer surface 37 of the ferrule 30 in the Y direction. The inner surfaces 54 and 55 are provided with V-shaped protrusions 54a and 55a, respectively, for guiding the V-grooves 36a and 37a of the ferrule 30. The V-shaped protrusions 54a and 55a are disposed symmetrically with respect to the center of the insertion hole 51 in the Y direction, for example. The V-shaped protrusions 54a and 55a are each V-shaped in a YZ cross section. The V-shaped protrusions 54a protrude from the inner surface 54 toward the outer surface 36 of the ferrule 30 and abut against the V-groove 36a of the outer surface 36. The V-shaped protrusion 54a is provided, for example, to extend continuously along the X direction on the inner surface 54. The V-shaped protrusion 55a protrudes from the inner surface 55 toward the outer surface 37 of the ferrule 30 and abuts against the V-groove 37a on the outer surface 37. The V-shaped protrusion 55a is provided, for example, to extend continuously along the X direction on the inner surface 55.

[0068] The V-protrusion 54a has a shape corresponding to the V-groove 36a. The opening angle of the V-protrusion 54a (i.e., the angle formed by the pair of outer surfaces that make up the V-protrusion 54a) is set smaller than the opening angle of the V-groove 36a of the ferrule 30 (i.e., the angle formed by the pair of inner surfaces that make up the V-groove 36a). The top of the V-protrusion 54a is, for example, rounded. The V-protrusion 55a has a shape corresponding to the V-groove 37a. The V-protrusion 55a has, for example, the same shape as the V-protrusion 54a. The distance between the V-protrusion 54a and the V-protrusion 55a in the Y direction is set slightly smaller than the width between the V-groove 36a and the V-groove 37a of the ferrule 30 in the Y direction. The distance between the V-protrusion 54a and the V-protrusion 55a in the Y direction can be defined as the distance between the top of the V-protrusion 54a and the top of the V-protrusion 55a when the ferrule 30 is not inserted into the adapter 50. The width in the Y direction between the V groove 36a and the V groove 37a can be defined as the distance in the Y direction between the bottom of the V groove 36a and the bottom of the V groove 37a.

[0069] The adapter 50 has a hollow portion 61 provided on one side of the insertion hole 51 in the Y direction. The hollow portion 61 is located outside the insertion hole 51 in the Y direction, sandwiching a wall portion 54W constituting the inner surface 54 therebetween. That is, the hollow portion 61 is adjacent to the insertion hole 51 in the Y direction via the wall portion 54W. The hollow portion 61 extends linearly along the X direction, for example, at a position aligned with the insertion hole 51 in the Y direction. The wall portion 54W extends in the Z direction between the hollow portion 61 and the insertion hole 51 to separate them. The thickness of the wall portion 54W (i.e., the width of the wall portion 54W in the Y direction) is, for example, constant. The thickness of the wall portion 54W is sufficiently thin to allow elastic deformation of the V-shaped protrusion 54a. Similarly, the thickness of the wall portion constituting the inner surface 55 is also sufficiently thin to allow elastic deformation of the V-shaped protrusion 55a. The presence of such hollow portion 61 makes it easier for the V-shaped protrusion 55a to be elastically deformed. No hollow portion is provided on the other outer side of the insertion hole 51 in the Y direction (i.e., on the opposite side of the insertion hole 51 with respect to the inner surface 55 in the Y direction).

[0070] In the optical connection structure 1 described above, when the ferrule 30 is inserted into the adapter 50, the V-groove 36a and V-groove 37a of the ferrule 30 are fitted into the V-protrusion 54a and V-protrusion 55a of the adapter 50, respectively. At this time, the V-protrusion 54a enters and abuts against the V-groove 36a of the ferrule 30, and the V-protrusion 55a enters and abuts against the V-groove 37a of the ferrule 30. Here, as described above, the distance between the V-protrusion 54a and V-protrusion 55a of the adapter 50 is set to be smaller than the width between the V-groove 36a and V-groove 37a of the ferrule 30. Therefore, the V-protrusion 54a and V-protrusion 55a of the adapter 50 receive a reaction force from the V-groove 36a and V-groove 37a of the ferrule 30, and are elastically deformed outward from the ferrule 30 in the Y direction. Then, a force acts on the ferrule 30 as the V-protrusions 54a and 55a of the adapter 50 return to their original positions, and the ferrule 30 is clamped and fixed between the V-protrusions 54a and 55a of the adapter 50.

[0071] As a result, the V-shaped protrusions 54a and 55a of the adapter 50 come into contact with the V-grooves 36a and 37a of the ferrule 30, respectively. Therefore, the gap between the V-shaped protrusions 54a and the V-groove 36a in the Y direction and the gap between the V-shaped protrusions 55a and the V-groove 37a in the Y direction are both zero. This determines the position of the ferrule 30 relative to the adapter 50 within the YZ plane, as well as the rotational position of the ferrule 30 relative to the adapter 50. Then, a spring (not shown) attached to the rear of the ferrule 30 biases the ferrule 30 in the X direction toward the mating ferrule 30, thereby determining the X-directional position of the ferrule 30 relative to the adapter 50 (see FIGS. 10 and 11 ). In this manner, the position of the ferrule 30 relative to the adapter 50 is determined.

[0072] If there is a gap in the Z direction between the V-protrusion 54a and the V-groove 36a (i.e., the difference between the Z-direction width of the V-protrusion 54a and the Z-direction width of the V-groove 36a) and a gap in the Z direction between the V-protrusion 55a and the V-groove 37a (i.e., the difference between the Z-direction width of the V-protrusion 55a and the Z-direction width of the V-groove 37a), the size of these gaps can cause a positional or angular misalignment between the ferrule 30 and the mating ferrule 30. Therefore, it is desirable to make these gaps as small as possible.

[0073] In this embodiment, the V-shaped protrusions 54a and 55a are part of the adapter 50, which is made of an elastic material. Therefore, both the V-shaped protrusions 54a and 55a are configured to be elastically deformable. However, for example, only the V-shaped protrusion 54a may be configured to be elastically deformable. In this case, the V-shaped protrusion 55a does not need to be configured to be elastically deformable. In this embodiment, the hollow portion 61 is provided outside the wall portion 54W on which the V-shaped protrusion 54a is provided (i.e., on the opposite side of the wall portion 54W from the receiving hole 39). Therefore, by forming the portion near the wall portion 54W from an elastic material, only the V-shaped protrusion 54a can be configured to be elastically deformable. In this case, when the ferrule 30 is inserted into the adapter 50, the V-shaped protrusion 55a, which does not elastically deform, is positioned so that the V-groove 37a of the ferrule 30 abuts against the V-shaped protrusion 55a, which does not elastically deform, and the V-shaped protrusion 54a, which does elastically deform, is abutted against the V-shaped groove 36a of the ferrule 30. At this time, the V-protrusion 54a receives a reaction force from the V-groove 36a and elastically deforms, and a force that causes the V-protrusion 54a to return to its original position is applied to the ferrule 30. As a result, the ferrule 30 is sandwiched and fixed between the V-protrusions 54a and 55a, and the position of the ferrule 30 relative to the adapter 50 is determined.

[0074] In this embodiment, the outer surface 36 and the outer surface 37 of the ferrule 30 are provided with V-grooves 36a and 37a, respectively. However, grooves having other shapes may be provided instead of the V-grooves 36a and 37a. For example, the outer surface 36 and the outer surface 37 of the ferrule 30 may be provided with U-grooves that are U-shaped in the YZ cross section, semicircular grooves that are semicircular in the YZ cross section, or rectangular grooves that are rectangular in the YZ cross section. Accordingly, the inner surfaces 54 and 55 of the adapter 50 may be provided with elliptical protrusions that are elliptical in the YZ cross section, semicircular protrusions that are semicircular in the YZ cross section, or rectangular protrusions that are rectangular in the YZ cross section, instead of the V-protrusions 54a and 55a. Alternatively, protrusions may be provided on the outer surface 36 and the outer surface 37 of the ferrule 30, or grooves may be provided on the inner surfaces 54 and 55 of the adapter 50. In this way, as long as it is possible to determine the position of the ferrule 30 relative to the adapter 50 when the ferrule 30 is fitted into the adapter 50, the combination of grooves and protrusions on the ferrule 30 and adapter 50 can be changed as appropriate.

[0075] The following describes the effects obtained by the ferrule 30 and optical connector 10 according to the present embodiment described above. In the present embodiment, when the optical fiber 20 is inserted into the ferrule 30 through the opening 33a, the optical fiber 20 is guided into the first fiber groove portion 41 by the second fiber groove portion 42, and the optical fiber 20 is positioned relative to the lens 31c in the first fiber groove portion 41. In this way, the presence of the second fiber groove portion 42 that guides the optical fiber 20 into the first fiber groove portion 41 reduces the possibility of the optical fiber 20 colliding with the wall portions between the fiber grooves 40 when inserting the optical fiber 20 into the ferrule 30, and the optical fiber 20 can be reliably positioned in the first fiber groove portion 41. Therefore, according to the present embodiment, the workability when assembling the optical fiber 20 into the ferrule 30 can be improved.

[0076] In this embodiment, the first fiber groove 41 and the second fiber groove 42 each have a V-shape in the YZ cross section, which allows the optical fiber 20 to be positioned with higher precision relative to the lens 31c.

[0077] In this embodiment, in the YZ cross section, the opening width W2 of the second fiber groove 42 is larger than the opening width W1 of the first fiber groove 41. This ensures that the allowable amount of misalignment of the optical fiber 20 supported in the second fiber groove 42 relative to the lens 31c is larger than the allowable amount of misalignment of the optical fiber 20 supported in the first fiber groove 41 relative to the lens 31c. As a result, when inserting the optical fiber 20 into the ferrule 30, the second fiber groove 42 determines the approximate position of the optical fiber 20 relative to the lens 31c, and then the first fiber groove 41 determines the position of the optical fiber 20 relative to the lens 31c with high accuracy. Therefore, with the above-described configuration, the second fiber groove 42 for guiding the optical fiber 20 into the first fiber groove 41 can be suitably realized.

[0078] In this embodiment, in the YZ cross section, the diameter d2 of an imaginary circle C2 centered on the optical axis of the lens 31c and inscribed in the second fiber groove 42 is larger than the diameter d1 of an imaginary circle C1 centered on the optical axis of the lens 31c and inscribed in the first fiber groove 41. This ensures that the allowable amount of misalignment of the optical fiber 20 supported in the second fiber groove 42 with respect to the lens 31c is greater than the allowable amount of misalignment of the optical fiber 20 supported in the first fiber groove 41 with respect to the lens 31c. As a result, when inserting the optical fiber 20 into the ferrule 30, the second fiber groove 42 determines the approximate position of the optical fiber 20 with respect to the lens 31c, and then the first fiber groove 41 determines the position of the optical fiber 20 with respect to the lens 31c with high accuracy. Therefore, the above-described configuration makes it possible to preferably realize the second fiber groove 42 for guiding the optical fiber 20 into the first fiber groove 41.

[0079] In this embodiment, the second fiber groove portion 42 includes a straight portion 42a in which the diameter d2 of the imaginary circle C2 is constant at each position along the X direction, and a tapered portion 42b that slopes so that the diameter d3 of the imaginary circle C3 increases with increasing distance from the straight portion 42a. The presence of this tapered portion 42b ensures that the optical fiber 20 inserted into the ferrule 30 from the opening 33a is guided reliably into the straight portion 42a. Furthermore, the presence of the straight portion 42a ensures that the orientation of the optical fiber 20 is stabilized along the X direction, allowing the optical fiber 20 to be smoothly introduced into the first fiber groove portion 41 while maintaining the stable orientation. Therefore, the above-described configuration ensures that the optical fiber 20 can be introduced reliably and smoothly into the first fiber groove portion 41.

[0080] In this embodiment, the total length L2 of the second fiber groove 42 is equal to or greater than the total length L1 of the first fiber groove 41. This makes it possible to more reliably stabilize the posture of the optical fiber 20 in the second fiber groove 42.

[0081] In this embodiment, the second fiber groove 42 is disposed at a predetermined distance from the first fiber groove 41. In this configuration, the first fiber groove 41 can be fabricated with high precision by forming the first fiber groove 41 separately from the second fiber groove 42. This makes it possible to suitably obtain the first fiber groove 41 for positioning the optical fiber 20 relative to the lens 31c.

[0082] In this embodiment, the first fiber groove portion 41 is located inside the window portion 34a when viewed from the Z direction. This allows the window portion 34a to be used not only as an injection window portion for injecting adhesive A into the inside of the ferrule 30, but also for the alignment work when introducing the optical fiber 20 into the first fiber groove portion 41. This further improves the workability when assembling the optical fiber 20.

[0083] In this embodiment, the outer surface 36 and the outer surface 37 are provided with V-grooves 36a and 37a, respectively, that guide the insertion into the adapter 50 along the X direction. This makes it possible to determine the position of the ferrule 30 relative to the adapter 50 using the V-grooves 36a and 37a. In other words, it is possible to position the ferrule 30 relative to the adapter 50 without using expensive guide pins.

[0084] In this embodiment, the optical fiber 20 is fixed to the first fiber groove portion 41 by adhesive A. As a result, the position of the optical fiber 20 relative to the lens 31c is fixed by adhesive A, so that the positioning of the optical fiber 20 relative to the lens 31c can be more reliably performed.

[0085] In this embodiment, a lid B is provided inside the window 34a and placed on the first fiber groove 41 via the optical fiber 20. The lid B presses the optical fiber 20 against the first fiber groove 41, thereby enabling more reliable positioning of the optical fiber 20 relative to the lens 31c.

[0086] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the claims.

[0087] FIG. 13 is a rear view showing a modified example of the optical connection structure 1 described above. FIG. 13 shows a cross section of the adapter 50A cut along the YZ plane. In the optical connection structure 1A shown in FIG. 13, the adapter 50A is made of a non-elastic material. Examples of materials for the adapter 50A include PPS (polyphenylene sulfide). The adapter 50A does not have the hollow portion 61 described above. In this case, elastic deformation of the adapter 50A is unlikely to occur even if a particularly hard material is not used as the material for the adapter 50A.

[0088] As shown in FIG. 13 , semicircular protrusions 54b and 55b are provided on the inner surfaces 54 and 55 of the adapter 50A, respectively, instead of the V-shaped protrusions 54a and 55a. The semicircular protrusions 54b and 55b are each semicircular in the YZ cross section. The semicircular protrusions 54b and 55b are in contact with the V-grooves 36a and 37a of the ferrule 30, respectively. The distance between the semicircular protrusions 54b and 55b in the Y direction is slightly larger than the width between the V-grooves 36a and 37a of the ferrule 30 in the Y direction. The distance between the semicircular protrusions 54b and 55b can be defined as the distance in the Y direction between the top of the semicircular protrusion 54b and the top of the semicircular protrusion 55b when the ferrule 30 is not inserted into the adapter 50A. A small gap is generated between the semicircular protrusion 54b and the V-groove 36a in the Y direction, and between the semicircular protrusion 55b and the V-groove 37a in the Y direction.

[0089] FIG. 14 is a side view showing the optical connection structure 1A. FIG. 14 shows a cross section of the adapter 50A cut along the XZ plane. As shown in FIG. 14, both ends of the semicircular protrusion 54b in the X direction are tapered as they move away from each other in the X direction. When the ferrule 30 is inserted into the adapter 50A and fitted, the ferrule 30 is moved along the X direction from one end of the adapter 50A to the other end in the X direction. At this time, the semicircular protrusion 54b enters and abuts against the V-groove 36a (see FIG. 13) of the ferrule 30, and the semicircular protrusion 55b (see FIG. 13) enters and abuts against the V-groove 37a of the ferrule 30. As a result, the ferrule 30 is held by the semicircular protrusions 54b and 55b of the adapter 50A, and the position of the ferrule 30 relative to the adapter 50A is determined.

[0090] Therefore, the optical connection structure 1A according to this modification also achieves the same effects as the optical connection structure 1 according to the above-described embodiment. When the adapter 50A is made of a material that does not elastically deform, as in this modification, if the V-groove 36a and the V-groove 37a are configured to fit into the V-protrusions 54a and 55a, respectively, as in the above-described embodiment, gaps are likely to occur between the V-groove 36a and the V-protrusion 54a in the Y direction and between the V-groove 37a and the V-protrusion 55a in the Y direction due to the influence of manufacturing tolerances, etc. In this case, it is expected that the position of the ferrule 30 relative to the adapter 50A will be significantly misaligned depending on the contact positions between the V-groove 36a and the V-groove 37a and the V-protrusions 54a and 55a. In contrast, by configuring the V-groove 36a and the V-groove 37a to fit into the semicircular protrusions 54b and 55b, respectively, it is possible to prevent such misalignment of the ferrule 30 relative to the adapter 50A.

[0091] The ferrule and optical connector of the present disclosure are not limited to the above-described embodiments and modifications, and various other modifications are possible. For example, in the above-described embodiments and modifications, the configuration of the ferrule can be changed as appropriate. For example, although the above-described embodiments illustrate cases in which the ferrule is integrally configured with the lens portion, the ferrule may be configured separately from the lens portion. In this case, the ferrule may be configured from a material other than optically transparent resin. [Explanation of symbols]

[0092] 1,1A...Optical connection structure 10...Optical connector 20...Optical fiber 30...Ferrule 31...Lens section 31a...front end surface 31b...Rear end surface 31c...lens 32…Front end surface (tip end surface) 33...Rear end surface 33a...Opening 34...Outer surface (top surface) 35…Outer surface 36,37...Outer surface (side) 34a...Window section 34b...Window section 36a, 37a...V groove (guide part) 39...Housing hole 40...Fiber groove 41...first fiber groove portion 42...Second fiber groove 41a...Tapered portion (second tapered portion) 41c...Tapered portion (first tapered portion) 42b...Tapered section 41b, 42a...Straight section 50,50A...adapter 51...insertion hole 52, 53, 54, 55...Inside 54a,55a…V protrusion 54b, 55b...Semicircular protrusions 54W…Wall part 61...Hollow part A...Adhesive B…Lid part C0…center C1, C2, C3...virtual circles D1, D2, D3...Depth d1,d2,d3…Diameter L1,L2…Total length R…Distance S1, S2, S3...Inner surface W1, W2...Opening width

Claims

1. The tip surface and an opening provided on the opposite side to the tip surface in a first direction intersecting the tip surface; a plurality of fiber grooves extending along the first direction between the tip surface and the opening and arranged along a second direction intersecting the first direction, each capable of supporting a plurality of optical fibers; a plurality of lenses respectively arranged on extension lines of the plurality of fiber grooves, The fiber groove is a first fiber groove for positioning the optical fiber relative to the lens; a second fiber groove portion for introducing the optical fiber into the first fiber groove portion; the first fiber groove portion is disposed closer to the lens than the second fiber groove portion in the first direction, The first fiber groove portion is a straight portion in which the diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the first fiber groove portion is constant at each position along the first direction; a first tapered portion disposed between the straight portion and the second fiber groove portion in the first direction, and inclined so that the diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the first fiber groove portion increases with increasing distance from the straight portion; a second tapered portion disposed between the lens and the straight portion in the first direction, the second tapered portion inclined such that a diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the first fiber groove portion increases with increasing distance from the straight portion.

2. 2. The ferrule according to claim 1, wherein in a cross section perpendicular to the first direction, each of the first fiber groove portion and the second fiber groove portion has a V-shape.

3. 3. The ferrule according to claim 1, wherein an opening width of the second fiber groove portion is larger than an opening width of the first fiber groove portion in a cross section perpendicular to the first direction.

4. 4. The ferrule according to claim 1, wherein in a cross section perpendicular to the first direction, a depth of the second fiber groove portion is greater than a depth of the first fiber groove portion.

5. 5. The ferrule according to claim 1, wherein, in a cross section perpendicular to the first direction, a diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the second fiber groove portion is larger than a diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the first fiber groove portion.

6. The second fiber groove portion is a straight portion in which the diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the second fiber groove portion is constant at each position along the first direction; 6. The ferrule according to claim 5, further comprising: a tapered portion that is disposed on an opposite side of the straight portion from the first fiber groove portion in the first direction, the tapered portion being inclined such that a diameter of an imaginary circle that is centered on the optical axis of the lens and inscribed in the second fiber groove portion increases with increasing distance from the straight portion.

7. 7. The ferrule according to claim 1, wherein the entire length of the second fiber groove portion in the first direction is equal to or greater than the entire length of the first fiber groove portion in the first direction.

8. 7. The ferrule according to claim 1, wherein the second fiber groove portion is disposed at a predetermined distance from the first fiber groove portion in the first direction.

9. an upper surface disposed at a position facing the plurality of fiber grooves in a third direction intersecting the first direction and the second direction; the upper surface has a window portion that opens in a region facing the first fiber groove portion in the third direction, 9. The ferrule according to claim 1, wherein the first fiber groove portion is located inside the window portion when viewed from the third direction.

10. 10. The ferrule of claim 9, wherein a total length of the first fiber groove portions in the first direction is less than a width of the window portions in the first direction, and a total width of all the first fiber groove portions in the second direction is less than a width of the window portions in the second direction.

11. a pair of side surfaces disposed opposite to each other across the plurality of fiber grooves in the second direction; 9. The ferrule according to claim 1, wherein the pair of side surfaces are provided with guide portions that guide insertion into the adapter along the first direction.

12. The ferrule according to claim 1 , wherein the ferrule is integral with the lens.

13. A ferrule according to any one of claims 1 to 12; the plurality of optical fibers supported in the plurality of fiber grooves and arranged on the optical axes of the plurality of lenses; An optical connector comprising:

14. 14. The optical connector according to claim 13, wherein the optical fiber is fixed in the first fiber groove by an adhesive.

15. the ferrule has an upper surface disposed at a position facing the plurality of fiber grooves in a third direction intersecting the first direction and the second direction, the upper surface has a window portion that opens in a region facing the first fiber groove portion in the third direction, 15. The optical connector according to claim 14, wherein a lid portion is provided inside the window portion and is placed over the first fiber groove portion with the optical fiber interposed therebetween.

16. the first fiber groove portion includes a straight portion in which a diameter of an imaginary circle centered on the optical axis of the lens and inscribed in the first fiber groove portion is constant at each position along the first direction, The optical connector according to claim 15 , wherein the cover portion is disposed in a region inside the window portion that faces the straight portion in the third direction.

17. 17. The optical connector according to claim 15, wherein the lid portion is a plate-like member formed separately from the ferrule and is positioned so as to contact the plurality of optical fibers supported in the plurality of fiber grooves, respectively.

18. 18. The optical connector according to claim 13, wherein the total length of the first fiber groove portion in the first direction is set in a range of 3 times to 40 times the diameter of the optical fiber.

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