Optical fiber array

Abstract

An optical fiber array is provided with a multi-core optical fiber. The outer peripheral shape of the glass cladding in a cross section orthogonal to the longitudinal direction has a first convex curved surface and a second convex curved surface which are symmetrical about a first axis and protrude away from the first axis, and a first surface and a second surface which are symmetrical about a second axis orthogonal to the first axis and cut toward the second axis side compared with the extension of the first convex curved surface and the extension of the second convex curved surface; a disposition member having a trapezoidal groove in a cross-section orthogonal to the longitudinal direction, the trapezoidal groove being configured from a first side surface, a second side surface, and a bottom surface facing the opening; and a pressing member that presses the glass fiber toward the arrangement member and fixes the glass fiber in the groove, and in a state where the first surface is in surface contact with the pressing member, the first convex curved surface is in contact with the first side surface, the second convex curved surface is in contact with the second side surface, or a boundary portion between the first convex curved surface and the second surface is in contact with the first side surface, and a boundary portion between the second surface and the second convex curved surface is in contact with the second side surface.

Description

[0001] This application is a divisional application based on Chinese national application No. 201980013455.8 (fiber optic array) filed on March 28, 2019, the contents of which are cited below. Technical Field

[0002] The present invention relates to optical fiber arrays.

[0003] This application claims the benefit of Japanese Patent Application No. 2018-064385, filed on March 29, 2018, the entirety of which is incorporated herein by reference. Background Art

[0004] A multi-core optical fiber consists of multiple cores covered by a common cladding, which increases the transmission capacity of each optical fiber. To connect two multi-core optical fibers, for example, the following method is known: first, the multi-core optical fibers are arranged in a V-shaped groove (V-groove), the arrangement of the cores is aligned (also called rotation alignment) in a specific direction, and then pressed from above with a pressing plate.

[0005] When a multi-core optical fiber is circular in cross-section, it is difficult to align the cores in a specific direction. Therefore, for example, Patent Document 1 discloses a multi-core optical fiber structure in which a portion of the outer surface of the cladding is cut away to form a flat surface, resulting in a substantially D-shaped cross-section perpendicular to the longitudinal direction.

[0006] Patent Document 1: U.S. Patent Application No. 2011 / 0229086 Summary of the Invention

[0007] An optical fiber array according to one embodiment of the present invention comprises: a multi-core optical fiber having a glass fiber and a resin coating, wherein the glass fiber has a plurality of cores and a cladding surrounding the plurality of cores, the resin coating covering the glass fiber, the outer peripheral shape of the cladding of the multi-core optical fiber comprising a first convex curved surface, a second convex curved surface, a first surface, and a second surface, the first convex curved surface and the second convex curved surface in a cross section perpendicular to the longitudinal direction of the multi-core optical fiber being symmetrical about a first axis and convex away from the first axis, the first surface in a cross section perpendicular to the longitudinal direction of the multi-core optical fiber being The shape of the first and second surfaces is symmetrical with respect to a second axis orthogonal to the first axis and is cut into the second axis side compared to the extension of the first convex surface and the extension of the second convex surface, and the length of the first and second surfaces of the cladding in the second axis direction is longer than the length of the outer peripheral shape of the cladding in the first axis direction; a configuration component having a groove for arranging glass fibers, the groove accommodating the glass fibers exposed from the resin coating at one end of the multi-core optical fiber, and the inner peripheral shape of the groove in a cross section orthogonal to the longitudinal direction is such that it approaches from the opening toward the bottom of the groove. and a pressing member that presses the glass fiber toward the arrangement member and fixes it in the groove, wherein the trapezoidal shape of the groove of the arrangement member is set as follows: before the glass fiber is pressed toward the bottom of the groove by the pressing member, the first convex surface of the cladding contacts the first side surface of the groove, the boundary portion of the first convex surface and the second surface contacts the bottom surface, and the second convex surface contacts the first convex surface. The second side surfaces of the cladding are in contact with each other, and when an angle φ is defined as φ between the second axis passing through the center of the cladding before the glass fiber is pressed toward the groove bottom by the pressing member and the first side surface or the second side surface, φ is less than or equal to π / 2. In a state in which the first surface of the cladding is in surface contact with the pressing member, the first convex curved surface of the cladding is in contact with the first side surface, and the second convex curved surface is in contact with the second side surface, or the boundary between the first convex curved surface and the second surface is in contact with the first side surface, and the boundary between the second surface and the second convex curved surface is in contact with the second side surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A This is a perspective view of an optical fiber array according to one embodiment of the present invention.

[0009] Figure 1B yes Figure 1A Sagittal section view along line II-II.

[0010] Figure 1C yes Figure 1B A partial enlarged view of .

[0011] Figure 1D yes Figure 1AA front cross-sectional view of a trapezoidal groove of a groove substrate included in an optical fiber array.

[0012] Figure 2 This is a cross-sectional view of a barrel-shaped fiber perpendicular to its longitudinal direction.

[0013] Figure 3A This is a diagram for explaining the relationship between barrel-shaped glass fibers and trapezoidal grooves.

[0014] Figure 3B This is a diagram for explaining the relationship between barrel-shaped glass fibers and trapezoidal grooves.

[0015] Figure 3C This is a diagram for explaining the relationship between barrel-shaped glass fibers and trapezoidal grooves.

[0016] Figure 4A This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal grooves of Sample 1 before rotational alignment.

[0017] Figure 4B This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal groove of Sample 1 after rotational alignment.

[0018] Figure 5A This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal grooves of Sample 2 before rotational alignment.

[0019] Figure 5B This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal groove of Sample 2 after rotational alignment.

[0020] Figure 6A This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal grooves of Sample 3 before rotational alignment.

[0021] Figure 6B This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal grooves of Sample 4 before rotational alignment.

[0022] Figure 6C This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal groove of Sample 5 before rotational alignment.

[0023] Figure 6D This figure shows the state of the barrel-shaped glass fiber arranged in the trapezoidal grooves of Sample 6 before rotational alignment. DETAILED DESCRIPTION

[0024] First, the contents of the embodiments of the present invention are listed and described. One embodiment of the present invention involves an optical fiber array, (1) which has: a multi-core optical fiber, which has a glass fiber and a resin coating, the glass fiber has a plurality of cores and a cladding surrounding the plurality of cores, the resin coating covers the glass fiber, the outer peripheral shape of the cladding has a first convex surface, a second convex surface, a first surface, and a second surface, the shapes of the first convex surface and the second convex surface in a cross section perpendicular to the longitudinal direction of the multi-core optical fiber are symmetrical about the first axis and protrude away from the first axis, the shapes of the first surface and the second surface in a cross section perpendicular to the longitudinal direction of the multi-core optical fiber are symmetrical about the second axis perpendicular to the first axis and cut into the second axis side compared to the extension of the first convex surface and the extension of the second convex surface;

[0025] an arrangement member having a groove in which the glass fiber is arranged, the groove accommodating the glass fiber exposed from the resin coating at one end of the multi-core optical fiber, wherein the inner peripheral shape of the groove in a cross section perpendicular to the longitudinal direction of the groove is a trapezoidal shape consisting of a first side surface and a second side surface arranged opposite to each other so as to approach the groove bottom from the opening, and a bottom surface opposite to the opening and connected to the first side surface and the second side surface; and

[0026] A pressing member presses the glass fiber toward the placement member to fix it in the groove,

[0027] When the first surface of the cladding of the optical fiber array is in surface contact with the pressing component, the first convex surface of the cladding is in contact with the first side surface, and the second convex surface is in contact with the second side surface, or the boundary between the first convex surface and the second surface is in contact with the first side surface, and the boundary between the second surface and the second convex surface is in contact with the second side surface.

[0028] (2) In one embodiment of the optical fiber array of the present invention, the trapezoidal shape is such that the first convex surface of the cladding can contact the first side surface of the groove, the boundary portion between the first convex surface and the second side surface can contact the bottom surface, and the second convex surface can contact the second side surface. This allows the multi-core optical fiber to be easily rotated within the groove. In this case, (3) may be such that, when the angle formed by the second axis passing through the center of the cladding and the first side surface or the second side surface is φ, φ is less than or equal to π / 2.

[0029] (4) In one embodiment of the optical fiber array of the present invention, the trapezoidal shape is such that the first convex surface of the cladding can contact the first side surface and the bottom surface of the groove, respectively, and the second surface can contact the second side surface. This allows the multi-core optical fiber to be easily rotated within the groove. In this case, (5) may be such that, when the angle formed by the extension of the first side surface relative to the opening and the extension of the second side surface is θ, θ is greater than or equal to π / 2.

[0030] (6) In one embodiment of the optical fiber array of the present invention, the arrangement member arranges the glass fibers exposed from the resin coating at one end of the multi-core optical fibers in parallel. This allows the arranged multi-core optical fibers to be easily rotated within the grooves.

[0031] [Details of the embodiments of the present invention]

[0032] Hereinafter, preferred embodiments of the optical fiber array according to the present invention will be described with reference to the accompanying drawings.

[0033] As for the multi-core optical fiber described in Patent Document 1, it is asymmetrical with respect to a plane containing a central axis and parallel to a flat surface. If a portion of the outer surface of the optical fiber mother material is cut off and made into a flat surface and then drawn, the optical fiber becomes easy to warp toward the flat surface side (easy to curl). In order to solve this situation, it is conceivable to set the outer peripheral shape of the multi-core optical fiber to have two opposite flat surfaces. However, if the multi-core optical fiber with two opposite flat surfaces is arranged in a V-groove, the multi-core optical fiber sinks to the bottom of the V-groove, and therefore there is a problem that it is not easy to align the arrangement direction of the fiber cores to a specific direction. The purpose of the present invention is to provide an optical fiber array that can easily align the arrangement direction of a plurality of fiber cores to a desired direction.

[0034] Figure 1A This is an oblique view of an optical fiber array 1 involved in one embodiment of the present invention. The optical fiber array 1 is composed of a groove substrate 40, a flat plate 60, and a plurality of multi-core optical fibers 10. In addition, the groove substrate 40 is equivalent to the configuration component of the present invention, and the flat plate 60 is equivalent to the pressing component of the present invention. The groove substrate 40 has a trapezoidal groove 50 that opens upward (in the positive direction of the Y axis shown in the figure). The trapezoidal groove 50 is equivalent to the groove of the present invention. The trapezoidal groove 50 can support the barrel-shaped glass fiber 12 exposed at one end of the multi-core optical fiber 10 along the Z-axis direction shown in the figure.

[0035] Figure 1B It is a sagittal cross-sectional view taken along line II-II in FIG1 . In this embodiment, a plurality of trapezoidal grooves 50 (e.g., 8) are provided, which are arranged along the X-axis direction shown in the figure. In this embodiment, an example of an array of 8 trapezoidal grooves 50 is given for explanation, but the present invention can also be applied to a case where there is only one trapezoidal groove 50. The plane plate 60 is, for example, in the shape of a flat plate, and the flat surface 61 covers the trapezoidal groove 50 to restrict the upward movement of the barrel-shaped glass fiber 12 made of quartz glass exposed from the front end of the multi-core optical fiber 10. In this embodiment, the multi-core optical fiber 10 is arranged, for example, in the X-axis direction shown in the figure. In addition, the barrel-shaped glass fiber 12 is equivalent to the glass fiber of the present invention. Figure 1C yes Figure 1BThe barrel-shaped glass fiber 12 has a plurality of (eg, four) cores 20 and a cladding 30 surrounding each core 20, and extends along the Z-axis direction (equivalent to the optical axis) shown in the figure.

[0036] Figure 1D This is a front cross-sectional view of a trapezoidal groove 50. The inner circumference of the trapezoidal groove 50 is, for example, an isosceles trapezoid facing downward. Specifically, the trapezoidal groove 50 has a first side surface 51 and a second side surface 52 arranged opposite each other. The first side surface 51 and the second side surface 52 are tapered from the opening 53 downward (toward the groove bottom). The angle formed by the extension of the first side surface 51 and the extension of the second side surface 52 is θ. Furthermore, a bottom surface 54 is provided opposite the opening 53 and is connected to the lower ends of the first side surface 51 and the lower ends of the second side surface 52.

[0037] Figure 2 This is a cross-sectional view of a barrel-shaped fiber taken orthogonally to the Z axis. The cores 20 are arranged at equal intervals along the second axis shown in the figure. The cladding 30 surrounds the entire circumference of the four cores 20 and has a non-circular shape (e.g., barrel-shaped) that is linearly symmetrical about both the X and Y axes shown in the figure. The outer periphery of the cladding 30 includes a first convex surface 31 and a second convex surface 32, which are linearly symmetrical about the cladding's minor axis (first axis); and an upper surface (first surface) 33 and a lower surface (second surface) 34, which are linearly symmetrical about the cladding's major axis (second axis), which is orthogonal to the cladding's minor axis.

[0038] Specifically, the first convex surface 31 is curved so as to convexly extend away from the minor axis of the cladding 30 (in other words, the center of the cladding). The second convex surface 32 is, for example, located on a different circumference than the circumference constituting the first convex surface 31 (although it may also be located on the same circumference as the circumference constituting the first convex surface 31). Like the first convex surface 31, it is curved so as to convexly extend away from the minor axis of the cladding 30. The upper surface 33 is parallel to the second axis and is cut into the second axis side (inward toward the center of the cladding 30) relative to the extension of the circumference constituting the first and second convex surfaces 31 and 32. The lower surface 34 is parallel to the second axis at a position opposite to the upper surface 33 and, like the upper surface 33, is cut into the second axis side relative to the extension of the circumference constituting the first and second convex surfaces 31 and 32.

[0039] As described above, since the outer periphery of the cladding 30 is symmetrical with respect to both the intersecting first and second axes, fiber curling can be prevented. Furthermore, the core and cladding can be primarily composed of quartz glass, with additives added to adjust the refractive index as needed. For example, the core can be made of quartz glass doped with GeO2, and the cladding can be made of pure quartz glass. Alternatively, the core can be made of pure quartz glass, and the cladding can be made of quartz glass doped with the element F. Furthermore, the diameters and refractive indices of the cores can differ.

[0040] Figure 3A 、 Figure 3B 、 Figure 3C This figure illustrates the relationship between the barrel-shaped glass fiber 12 and the trapezoidal groove 50. The cross-sectional shape of the cladding 30 of the barrel-shaped glass fiber 12 is composed of curved surfaces and flat surfaces. Therefore, point A, the boundary between the upper surface 33 and the first convex surface 31, point B, the boundary between the first convex surface 31 and the lower surface 34, point C, the boundary between the lower surface 34 and the second convex surface 32, and point D, the boundary between the second convex surface 32 and the upper surface 33, constitute edges.

[0041] If the curvature radius of the first convex surface 31 (second convex surface 32 ) is r and the distance from the center of the first convex surface 31 to the center of the second convex surface 32 is d, the line segment BC can be expressed by the following formula 1.

[0042] [Formula 1]

[0043]

[0044] If the maximum height of the cladding 30 is h1, in order to rotate the glass fiber 12 by being pressed by the flat plate 60, it is necessary to satisfy h1 ≤ line segment BC, which yields the following formula 2.

[0045] [Formula 2]

[0046]

[0047] When this equation 2 is solved with respect to h1, the following equation 3 is obtained.

[0048] [Formula 3]

[0049]

[0050] When the length of the bottom surface 54 of the trapezoidal groove 50 (in the X-axis direction shown in the figure, the same applies hereinafter) is set to W, W has an upper limit and a lower limit for preventing the positional deviation of the core 20. Specifically, Figure 3AAs shown, the lower surface 34 of the cladding 30 is arranged parallel to the bottom surface 54, and the length W of the bottom surface 54 becomes the maximum value W when it is equal to the length of the lower surface 34. max (Formula 4).

[0051] [Formula 4]

[0052]

[0053] In this case, a straight line descending from the center of the first convex surface 31 (second side surface 52 ) to point B (point C) is perpendicular to (tangent to) the first side surface 51 (second side surface 52 ).

[0054] When the depth of the trapezoidal groove 50 is set to h2, and the protrusion amount of the cladding 30 is set to h head , use the maximum value W of the length of the bottom surface 54 max If , h2 becomes the following formula 5.

[0055] [Formula 5]

[0056]

[0057] On the other hand, the length W of the bottom surface 54 is as follows Figure 3B 、 Figure 3C As shown, the minimum value W is achieved when the second axis (the major axis of the cladding 30) passing through the center of the first convex surface 31 and the center of the second convex surface 32 is perpendicular to the first side surface 51 and the boundary portion 35 (point B) between the first convex surface 31 and the lower surface 34 contacts the bottom surface 54. min If you use Figure 3B 、 Figure 3C For c, a, e, f, and g shown in FIG, there is a relationship of c+a+e=f+g. Since c=h1 / 2, a becomes the following formula 6, and e becomes the following formula 7.

[0058] [Formula 6]

[0059]

[0060] [Formula 7]

[0061]

[0062] In addition, i=r-√(r 2 -c 2 ).

[0063] Furthermore, f=(d+r) / tanθ, g=r / sinθ, and therefore, substituting these into Formula 6 yields the following Formula 8.

[0064] [Formula 8]

[0065]

[0066] Figure 4A 、 Figure 4B This is a conceptual diagram illustrating a first specific example of the optical fiber array of the present invention. Figure 4A This figure shows the barrel-shaped glass fiber before rotational alignment. The trapezoidal groove 50 is shaped so that, before the barrel-shaped glass fiber 12 is pressed downward by the flat plate 60, the cladding 30, from the first convex surface 31 through the lower surface 34 to the second convex surface 32, contacts the trapezoidal groove 50 at a total of three locations: the first side surface 51, the bottom surface 54, and the second side surface 52.

[0067] In more detail, Figure 4A The trapezoidal groove 50 shown (referred to as Sample 1) has a shape such that the first convex surface 31 of the cladding 30 is in line contact with the first side surface 51 (a line extending in the optical axis direction, the same applies hereinafter), the boundary 35 between the first convex surface 31 and the lower surface 34 is in line contact with the bottom surface 54, and the second convex surface 32 is in line contact with the second side surface 52. The trapezoidal groove 50 of Sample 1 preferably has a shape such that φ is less than or equal to π / 2 in order to reliably prevent the barrel-shaped glass fiber 12 from sinking, assuming the angle formed between the second axis (indicated by a dashed line in the figure) passing through the center of the cladding 30 and the first side surface 51 is φ. In this case, the depth h2 of the trapezoidal groove 50 is such that φ is less than or equal to π / 2.

[0068] Figure 4B This diagram shows the state of a barrel-shaped glass fiber after rotational alignment. After placing the barrel-shaped glass fiber 12 in the trapezoidal groove 50 of Sample 1, if the flat plate 60 is lowered toward the barrel-shaped glass fiber 12, the flat surface 61 contacts the vicinity of the boundary between, for example, the upper surface 33 and the second convex surface 32 of the cladding 30. If the flat plate 60 further presses the barrel-shaped glass fiber 12 downward, the boundary 35 between the first convex surface 31 and the lower surface 34 separates from the bottom surface 54, causing the barrel-shaped glass fiber 12 to rotate clockwise. The upper surface 33 contacts the flat surface 61, and the lower surface 34 becomes parallel to the bottom surface 54. At this point, the height of the line of contact between the first convex surface 31 and the first side surface 51 and the height of the line of contact between the second convex surface 32 and the second side surface 52 from the bottom surface 54 are approximately equal.

[0069] As described above, the trapezoidal groove 50 is formed into a trapezoidal shape such that, after the barrel-shaped glass fiber 12 is pressed downward, the upper surface 33 and lower surface 34 of the cladding 30 are arranged parallel to the flat surface 61. Therefore, when the barrel-shaped glass fiber 12 is arranged in the trapezoidal groove 50, the barrel-shaped glass fiber 12 does not sink downward compared to conventional methods. Furthermore, the alignment position of the core 20 of the barrel-shaped glass fiber 12 arranged in the trapezoidal groove 50 of Sample 1 after being pressed by the flat plate 60 was evaluated. The results showed that the deviation from the ideal position (maximum core eccentricity) was within ±1.0 μm.

[0070] Figure 5A 、 Figure 5B This is a conceptual diagram illustrating a second specific example of the optical fiber array of the present invention. Figure 5A : is a diagram showing the state of the barrel-shaped glass fiber before rotational alignment. In the second specific example, the shape of the trapezoidal groove 50 (set as sample 2) is as follows, that is, before the barrel-shaped glass fiber 12 is pressed downward by the flat plate 60, the first convex surface 31 of the cladding 30 is in line contact with the first side surface 51 and the bottom surface 54, respectively, and the lower surface 34 is in surface contact with the second side surface 52. When the angle formed by the extension of the first side surface 51 and the extension of the second side surface 52 of the trapezoidal groove 50 of sample 2 is set to θ, in order to reliably prevent the barrel-shaped glass fiber 12 from sinking, it is preferable that θ is greater than or equal to π / 2. When the groove depth is set to d th In the case of trapezoidal groove 50, the depth h2 is less than d th The trapezoidal groove 50 (sample 1) is a shape that is valid even when the angle θ formed by the first side surface 51 and the second side surface 52 is less than or equal to π / 2. However, in the case of sample 1, θ can also be set to be greater than or equal to π / 2.

[0071] Figure 5BThis diagram shows the state of a barrel-shaped glass fiber after rotational alignment. After placing the barrel-shaped glass fiber 12 in the trapezoidal groove 50 of Sample 2, if the flat plate 60 is lowered toward the barrel-shaped glass fiber 12, the flat surface 61 contacts the vicinity of the boundary between, for example, the upper surface 33 and the second convex surface 32 of the cladding 30. If the flat plate 60 further presses the barrel-shaped glass fiber 12 downward, the first convex surface 31 separates from the bottom surface 54, and the surface contact between the lower surface 34 and the second side surface 52 is released. The barrel-shaped glass fiber 12 rotates clockwise, the upper surface 33 contacts the flat surface 61, and the lower surface 34 becomes parallel to the bottom surface 54. At this point, the height of the line where the boundary 35 between the first convex surface 31 and the lower surface 34 contacts the first side surface 51 is equal to the height of the line where the boundary 36 between the lower surface 34 and the second convex surface 32 contacts the second side surface 52. The barrel-shaped glass fiber 12 disposed in the trapezoidal groove 50 of Sample 2 was evaluated for the arrangement position of the core 20 after being pressed by the flat plate 60. As a result, the maximum core eccentricity was within ±1.0 (μm).

[0072] Figure 6A 、 Figure 6B 、 Figure 6C 、 Figure 6D This is a diagram showing the state of a barrel-shaped glass fiber before rotational alignment. Figure 6A The length W of the bottom surface 54 of the trapezoidal groove 50 (sample 3) shown is longer than the lower surface 34 of the cladding 30. Therefore, the lower surface 34 is in surface contact with the bottom surface 54, while the first convex surface 31 (second convex surface 32) is not in contact with the first side surface 51 (second side surface 52). When the flat plate 60 is lowered toward the barrel-shaped glass fiber 12, the flat surface 61 is in surface contact with the upper surface 33, but the barrel-shaped glass fiber 12 moves left and right. Evaluation of the arrangement position of the core 20 revealed that the maximum core eccentricity did not fall within ±1.0 μm.

[0073] At once Figure 6B In the illustrated trapezoidal groove 50 (sample 4), the depth h2 of the trapezoidal groove 50 is large, causing the barrel-shaped glass fiber 12 to sink downward. Furthermore, the length W of the bottom surface 54 is shorter than the maximum height h1 of the cladding 30. Consequently, the first convex surface 31 is in line contact with both the first side surface 51 and the bottom surface 54, and the boundary 35 between the first convex surface 31 and the lower surface 34 is in line contact with the second side surface 52. When the flat plate 60 is lowered toward the barrel-shaped glass fiber 12, the flat surface 61 contacts the second convex surface 32, and the first convex surface 31 is pressed against the bottom surface 54, preventing the barrel-shaped glass fiber 12 from rotating.

[0074] Figure 6CIn the illustrated trapezoidal groove 50 (sample 5), the angle φ formed between the second axis (indicated by a dashed line in the figure) passing through the center of the cladding 30 and the first side surface 51 exceeds π / 2, causing the barrel-shaped glass fiber 12 to sink downward. Consequently, the first convex surface 31 makes line contact with both the first side surface 51 and the bottom surface 54, while the boundary 36 between the bottom surface 34 and the second convex surface 32 makes line contact with the second side surface 52. When the flat plate 60 is lowered toward the barrel-shaped glass fiber 12, the flat surface 61 contacts the second convex surface 32, and the first convex surface 31 is pressed against the first side surface 51 and the bottom surface 54, preventing the barrel-shaped glass fiber 12 from rotating.

[0075] At once Figure 6D In the illustrated trapezoidal groove 50 (sample 6), the angle θ formed by the extension of the first side surface 51 and the extension of the second side surface 52 is less than π / 2, causing the barrel-shaped glass fiber 12 to sink downward. Consequently, the first convex surface 31 is in line contact with the first side surface 51, while the lower surface 34 is in surface contact with the second side surface 52. When the flat plate 60 is lowered toward the barrel-shaped glass fiber 12, the flat surface 61 contacts the vicinity of the boundary between the upper surface 33 and the second convex surface 32. However, the first convex surface 31 is pressed by the first side surface 51, and the lower surface 34 is pressed by the second side surface 52, preventing the barrel-shaped glass fiber 12 from rotating.

[0076] The embodiments disclosed herein are illustrative in all respects and should not be construed as restrictive. The scope of the present invention is defined by the claims rather than the above, and is intended to encompass all modifications within the meaning and scope of the claims and equivalents.

[0077] Description of the label

[0078] 1…fiber array, 10…multi-core optical fiber, 11…resin coating, 12…barrel-shaped glass fiber, 20…fiber core, 30…cladding, 31…first convex curved surface, 32…second convex curved surface, 33…upper surface, 34…lower surface, 35…boundary portion between the first convex curved surface and the lower surface, 36…boundary portion between the lower surface and the second convex curved surface, 40…grooved substrate, 50…trapezoidal groove, 51…first side surface, 52…second side surface, 53…opening, 54…bottom surface, 60…flat plate, 61…flat surface.

Claims

1. An optical fiber array, comprising: A multi-core optical fiber comprising a glass fiber and a resin coating, the glass fiber having a plurality of cores and a cladding surrounding the plurality of cores, the resin coating covering the glass fiber, the outer peripheral shape of the cladding comprising a first convex curved surface, a second convex curved surface, a first surface, and a second surface, the first and second convex curved surfaces in a cross section perpendicular to a longitudinal direction of the multi-core optical fiber being symmetrical about a first axis and protruding away from the first axis, the first and second surfaces in a cross section perpendicular to the longitudinal direction of the multi-core optical fiber being symmetrical about a second axis perpendicular to the first axis and being incised toward the second axis side relative to extensions of the first and second convex curved surfaces, the lengths of the first and second surfaces of the cladding in the direction of the second axis being longer than the length of the outer peripheral shape of the cladding in the direction of the first axis; a placement member having a groove in which the glass fiber is placed, the groove accommodating the glass fiber exposed from the resin coating at one end of the multi-core optical fiber, wherein the inner circumference of the groove in a cross section perpendicular to the longitudinal direction of the groove is a trapezoidal shape consisting of a first side surface and a second side surface that are arranged opposite to each other so as to approach the groove bottom from the opening, and a bottom surface that is opposite to the opening and connected to the first side surface and the second side surface; as well as a pressing member that presses the glass fiber toward the placement member to fix it in the groove, The trapezoidal shape of the groove of the arrangement member is set to be such that, before the glass fiber is pressed toward the groove bottom by the pressing member, the first convex curved surface of the cladding contacts the first side surface of the groove, the boundary portion between the first convex curved surface and the second surface contacts the bottom surface, and the second convex curved surface contacts the second side surface. When an angle φ formed by the second axis passing through the center of the cladding and the first side surface or the second side surface before the glass fiber is pressed toward the groove bottom by the pressing member is defined as φ, φ is less than or equal to π / 2, When the first surface of the cladding is in surface contact with the pressing part, the first convex surface of the cladding is in contact with the first side surface, and the second convex surface is in contact with the second side surface, or the boundary portion between the first convex surface and the second surface is in contact with the first side surface, and the boundary portion between the second surface and the second convex surface is in contact with the second side surface.

2. The optical fiber array according to claim 1, wherein: The trapezoidal shape is a shape in which the first convex curved surface of the cladding layer can contact each of the first side surface and the bottom surface of the groove, and the second surface can contact the second side surface.

3. The optical fiber array according to claim 1 or 2, wherein: When an angle formed by an extension of the first side surface and an extension of the second side surface relative to the opening is denoted by θ, θ is equal to or greater than π / 2.

4. The optical fiber array according to any one of claims 1 to 3, wherein: The arrangement member arranges in parallel the glass fibers exposed from the resin coating at one end of the multi-core optical fiber.

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