Optical fiber connection structure

Abstract

A fiber connection structure according to one embodiment includes a tubular member, a first collimator attached to a first end of the tubular member in an axial direction, and a second collimator attached to a second end of the tubular member. The first collimator includes a first optical fiber, a first ferrule that holds the first optical fiber, a first lens, and a first sleeve that holds the first lens and the first ferrule inside. The second collimator includes a second optical fiber, a second ferrule that holds the second optical fiber, a second lens, and a second sleeve that holds the second lens and the second ferrule inside. The first sleeve is fixed to the first end via an adhesive in a state where the first lens opposes the tubular member, and the second sleeve is fixed to the second end via an adhesive in a state where the second lens opposes the tubular member. An outer diameter of the second ferrule is larger than an outer diameter of the second lens.

Description

Technical Field

[0001] This invention relates to optical fiber connection structures.

[0002] This application claims priority based on Japanese Application No. 2020-111739, dated June 29, 2020, and incorporates all the contents set forth in the aforementioned Japanese application. Background Technology

[0003] Patent Document 1 describes an optical functional component with a collimator. The collimator has a lens and a ferrule for holding an optical fiber. The optical functional component has a cylindrical tube that holds a collimator internally with a pair of lenses facing each other. A WDM filter or isolator is disposed between the pair of lenses inside the cylindrical tube.

[0004] Patent document 2 discloses a lens-type device having optical functional components such as an isolator. The lens-type device has a tubular component. Inside the tubular component are a pair of lenses and a Faraday element disposed between the pair of lenses.

[0005] Patent document 3 describes an optical isolator device. The optical isolator device includes a tubular metal component, an optical isolator disposed inside the tubular component, and a collimator fixed to the tubular component. The collimator has a ferrule for holding the optical fiber and a lens optically coupled to the isolator. Each collimator is fixed to the tubular component by spot welding.

[0006] Patent Document 1: US Patent No. 5,652,814

[0007] Patent Document 2: International Publication No. 2009 / 075168

[0008] Patent Document 3: Japanese Patent Application Publication No. 9-61683 Summary of the Invention

[0009] The optical fiber connection structure of the present invention comprises: a tubular component; a first collimator mounted at a first end in the axial direction of the tubular component; and

[0010] The second collimator is mounted at the second end of the tubular component, opposite to the first end. The first collimator has a first optical fiber, a first ferrule holding the first optical fiber, a first lens facing the first ferrule with a gap, and a first sleeve holding the first lens and the first ferrule internally. The second collimator has a second optical fiber, a second ferrule holding the second optical fiber, a second lens facing the second ferrule with a gap, and a second sleeve holding the second lens and the second ferrule internally. The outer surface of the first ferrule and the inner surface of the first sleeve, the outer surface of the first lens and the inner surface of the first sleeve, the outer surface of the second lens and the inner surface of the tubular component, and the outer surface of the second ferrule and the inner surface of the second sleeve are respectively fixed by adhesive. The first sleeve is fixed at the first end when the first lens is facing the tubular component, and the second sleeve is fixed at the second end when the second lens is inserted into the tubular component. The outer diameter of the second ferrule is larger than the outer diameter of the second lens. Attached Figure Description

[0011] Figure 1 This is a perspective view showing the optical fiber connection structure according to one embodiment.

[0012] Figure 2 yes Figure 1 A cross-sectional view of the fiber optic connection structure.

[0013] Figure 3 It is a cross-sectional view showing the ferrule and lens of the optical fiber connection structure involved in the comparative model.

[0014] Figure 4 This is a cross-sectional view showing the ferrule and lens of an optical fiber connection structure according to one embodiment.

[0015] Figure 5 This is a diagram illustrating one step of an assembly method for an optical fiber connection structure according to one embodiment.

[0016] Figure 6 This is a diagram illustrating one step of an assembly method for an optical fiber connection structure according to one embodiment.

[0017] Figure 7 This is a diagram illustrating one step of an assembly method for an optical fiber connection structure according to one embodiment.

[0018] Figure 8 This is a diagram illustrating one step of an assembly method for an optical fiber connection structure according to one embodiment.

[0019] Figure 9 This is a diagram illustrating one step of an assembly method for an optical fiber connection structure according to one embodiment.

[0020] Figure 10This is a diagram illustrating the optical fiber connection structure involved in one implementation.

[0021] Figure 11 This is a cross-sectional view showing the optical fiber connection structure involved in the modified example.

[0022] Figure 12 This is a cross-sectional view showing the optical fiber connection structure involved in other variations.

[0023] Figure 13 This is a perspective view showing the optical fiber connection structure involved in other variations.

[0024] Figure 14 This is a cross-sectional view showing the optical fiber connection structure involved in other variations.

[0025] Figure 15 This is a diagram illustrating an example of a single-core optical fiber.

[0026] Figure 16 This is a cross-sectional view showing the ferrule and lens of the optical fiber connection structure involved in other variations. Detailed Implementation

[0027] Furthermore, in fiber optic connection structures, when the ferrule is fixed to the tubular component with adhesive after it has entered the tubular component, the ferrule may tilt due to environmental changes such as temperature and humidity, depending on the thickness of the adhesive. In this case, the reliability of the optical connection may decrease. Additionally, when fixing the collimator to a metal tubular component by welding, advanced welding techniques are required, or various tools are needed for welding, which may make it difficult to easily fix the collimator.

[0028] The object of the present invention is to provide an optical fiber connection structure that allows for easy collimator fixation and improves the reliability of the optical connection.

[0029] According to the present invention, the collimator can be easily fixed, and the reliability of the optical connection can be improved.

[0030] [Description of embodiments of the present invention]

[0031] First, embodiments of the present invention will be described. One embodiment of the optical fiber connection structure includes: a tubular component; a first collimator mounted at a first end in the axial direction of the tubular component; and a second collimator mounted at a second end of the tubular component opposite to the first end. The first collimator includes a first optical fiber, a first ferrule holding the first optical fiber, a first lens facing the first ferrule with a gap, and a first sleeve internally holding the first lens and the first ferrule. The second collimator includes a second optical fiber, a second ferrule holding the second optical fiber, a second lens facing the second ferrule with a gap, and a second sleeve internally holding the second lens and the second ferrule. The outer surfaces of the first insert and the inner surfaces of the first sleeve, the outer surfaces of the first lens and the inner surfaces of the first sleeve, the outer surfaces of the second lens and the inner surfaces of the tubular component, and the outer surfaces of the second insert and the inner surfaces of the second sleeve are respectively fixed with adhesive. With the first lens facing the tubular component, the first sleeve is fixed at the first end. With the second lens inserted into the tubular component, the second sleeve is fixed at the second end. The outer diameter of the second insert is larger than the outer diameter of the second lens.

[0032] In this fiber optic connection configuration, a first collimator is installed at the first end of the tubular component, and a second collimator is installed at the second end of the tubular component opposite to the first end. The first collimator has a first sleeve, inside which a first lens and a first ferrule holding the first optical fiber are held. The second collimator has a second sleeve, inside which a second lens and a second ferrule holding the second optical fiber are held. The first sleeve is fixed to the first end when the first lens is facing the tubular component, and the second sleeve is fixed to the second end when the second lens is inserted into the tubular component. Therefore, by fixing the first collimator and the second collimator at the first and second ends respectively in the axial direction of the tubular component, the first and second collimators can be easily fixed to the tubular component. Furthermore, by fixing the first collimator and the second collimator at the first and second ends respectively, the tilt of the ferrule can be suppressed, thereby improving the reliability of the optical connection. The outer diameter of the second collimator's second insert is larger than the outer diameter of the second lens. Therefore, the second insert can be aligned in a direction orthogonal to the optical axis of the second lens while the second lens is fixed to the tubular component, thus facilitating alignment and component assembly.

[0033] The ends of the first sleeve and the first end of the tubular component, and the ends of the second sleeve and the second end of the tubular component, can be fixed by adhesive. The first sleeve and the tubular component, and the second sleeve and the tubular component can suppress their respective tilt, thereby improving the reliability of the optical connection.

[0034] The first lens may have a first lens end face opposite to the first ferrule. The first ferrule may have a first ferrule end face opposite to the first lens. The tilt angle of the first lens end face relative to a plane orthogonal to the axial direction may differ from the tilt angle of the first ferrule end face relative to a plane orthogonal to the axial direction, allowing light to be emitted from the first lens toward the tubular component along the axial direction. In this case, light is emitted along the axial direction of the tubular component, thus reducing beam distortion and further improving the reliability of optical coupling.

[0035] The second lens may have a second lens end face opposite to the second ferrule. The second ferrule may have a second ferrule end face opposite to the second lens. The tilt angle of the second lens end face relative to a plane orthogonal to the axial direction may differ from the tilt angle of the second ferrule end face relative to a plane orthogonal to the axial direction, allowing light to be emitted from the second lens toward the tubular component along the axial direction. In this case, similarly to the aforementioned, beam distortion can be reduced, further improving the reliability of optical coupling.

[0036] The end face of the first lens opposite the tubular component may be further inside the first sleeve than the end face of the first sleeve opposite the tubular component. In this case, the first lens will not protrude from the first sleeve, thus preventing interference between the first lens and the tubular component when the first collimator is aligned in a direction orthogonal to the optical axis of the first lens. Therefore, alignment and fixation of the first collimator can be easily performed.

[0037] At least one of the end face of the first lens opposite to the tubular component and the end face of the second lens entering the tubular component may be spherical. Additionally, at least one of the first and second lenses may be a GRIN lens.

[0038] The aforementioned fiber optic connection structure may have a Faraday element disposed inside the tubular component. In this case, the fiber optic connection structure can be configured as an optical isolator.

[0039] The first optical fiber can be a multi-core optical fiber. The second optical fiber can be multiple single-core optical fibers. Each of the multiple single-core optical fibers can have a beam amplification section capable of expanding the mode field diameter of light transmitted within the core of the single-core optical fiber. In this case, the optical fiber connection structure can be configured as a fan-in / fan-out device for multi-core optical fibers.

[0040] Either the first or second optical fiber can be a two-core fiber. The fiber optic connection structure can have a WDM filter configured inside the tubular component. In this case, the fiber optic connection structure can be configured as a WDM multiplexing / demultiplexing device.

[0041] The maximum thickness of the adhesive can be less than 50 μm. In this case, the maximum thickness of the adhesive can be set to be thin, less than 50 μm, thus making it easier to fix the collimator and further improving the reliability of the optical connection.

[0042] [Detailed Description of Embodiments of the Invention]

[0043] Hereinafter, specific examples of the optical fiber connection structure of the present invention will be described with reference to the accompanying drawings. Furthermore, the present invention is not limited to the examples described below, but is shown in the claims and includes all modifications within the scope equivalent to the claims. In the description of the drawings, the same or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted where appropriate. Additionally, regarding the drawings, for ease of understanding, some parts are sometimes simplified or exaggerated, and the scale and angles are not limited to those shown in the drawings.

[0044] Figure 1 This is a perspective view showing the optical fiber connection structure 1 according to the embodiment. Figure 2 This is a cross-sectional view showing fiber optic connection configuration 1. For example... Figure 1 and Figure 2 As shown, the fiber optic connection structure 1 includes a first collimator 2, a second collimator 3, and a tubular component 4. The first collimator 2 includes a first optical fiber 10, a first ferrule 13, a first lens 14, and a first sleeve 5. The second collimator 3 includes a second optical fiber 20, a second ferrule 23, a second lens 24, and a second sleeve 6. The tubular component 4 connects the first collimator 2 and the second collimator 3 to each other. The tubular component 4 is, for example, made of glass.

[0045] The first collimator 2 is installed at the first end 4b in the axial direction D of the tubular component 4. The first sleeve 5 of the first collimator 2 is fixed to the first end 4b, and can be fixed by adhesive or other various methods. When using an adhesive, for example, a UV (ultraviolet) curing adhesive is used. The first sleeve 5 and the first insert 13 are, for example, made of glass. When the tubular component 4 and the first sleeve 5 are made of glass, and the first sleeve 5 is fixed to the tubular component 4 by a UV curing adhesive, the difference in the coefficients of linear expansion between the tubular component 4 and the first sleeve 5 can be reduced, thus improving the reliability of the connection.

[0046] The first ferrule 13 holds the first optical fiber 10, and the front end face of the first optical fiber 10 faces the first lens 14. With the first lens 14 facing the tubular component 4, the first sleeve 5 is fixed to the first end 4b. The first lens 14 faces the first ferrule 13 and the first optical fiber 10 across a gap S1. The first sleeve 5 is cylindrical. The first ferrule 13 and the first lens 14 are held inside the first sleeve 5. The outer surface of the first ferrule 13 and the inner surface of the first sleeve 5, and the outer surface of the first lens 14 and the inner surface of the first sleeve 5 are respectively fixed with adhesive.

[0047] The second collimator 3 is mounted on the second end 4c of the tubular component 4, opposite to the first end 4b. The second sleeve 6 of the second collimator 3 is fixed to the second end 4c, for example, by adhesive, but various other fixing methods can be used. The second ferrule 23 holds the second optical fiber 20, the front end face of which faces the second lens 24. With the second lens 24 inserted into the tubular component 4, the second sleeve 6 is fixed to the second end 4c. The second lens 24 faces the second ferrule 23 and the second optical fiber 20 across a gap S2. The second sleeve 6 is cylindrical. The second ferrule 23 and the second lens 24 are held inside the second sleeve 6. The outer surface of the second ferrule 23 and the inner surface of the second sleeve 6 are fixed by adhesive.

[0048] The first lens 14 is, for example, a front spherical rod lens. The outer diameter of the first lens 14 is approximately the same as the outer diameter of the first insert 13. The inner diameter of the first sleeve 5 is slightly larger than the outer diameters of the first lens 14 and the first insert 13. A gap of 0 μm or more and 20 μm or less is formed between the outer peripheral surfaces of the first lens 14 and the first insert 13 and the inner peripheral surface of the first sleeve 5, respectively. The end face 14c of the first lens 14, which is opposite to the tubular member 4, extends further into the first sleeve 5 than the end face 5b of the first sleeve 5, which is opposite to the tubular member 4. Therefore, when the first collimator 2 is aligned in a direction orthogonal to the axial direction D, interference between the first lens 14 and the tubular member 4 can be avoided.

[0049] For example, the second lens 24 of the second collimator 3 is a front spherical rod lens. A portion of the second lens 24 is inserted into the interior of the tubular component 4. The outer diameter of the second lens 24 is slightly smaller than the inner diameter of the tubular component 4, smaller than the outer diameter of the second insert 23, and smaller than the inner diameter of the second sleeve 6. The outer diameter of the second insert 23 is larger than the inner diameter of the tubular component 4 and slightly smaller than the inner diameter of the second sleeve 6.

[0050] The length of the gap S1 formed between the first optical fiber 10 (first ferrule 13) and the first lens 14 in the axial direction is adjusted so that the light emitted from the first lens 14 toward the second lens 24 becomes collimated light. Figure 4This diagram illustrates the first optical fiber 10, the first ferrule 13, and the first lens 14 involved in the embodiment. Figure 3 This is a diagram showing the first optical fiber 110, the first ferrule 113, and the first lens 114 involved in the comparative example.

[0051] Furthermore, the refractive index of the first lens 114 sometimes differs from that of the first optical fiber 110, for example, it may be higher than the refractive index of the first optical fiber 110. In this case, such as... Figure 3 As shown, when the end face 113b (front end face of the first optical fiber 110) of the first ferrule 113 opposite to the first lens 114 and the face 114b of the first lens 114 opposite to the first ferrule 113 are parallel to each other, the light L emitted from the first optical fiber 110 may be tilted at the first lens 114 from the optical axis direction (axial direction D) of the first optical fiber 110.

[0052] In contrast, such as Figure 2 and Figure 4 As shown, when the first ferrule end face 13b (the front end face of the first optical fiber 10) of the first ferrule 13 opposite to the first lens 14 and the first lens end face 14b of the first lens 14 opposite to the first ferrule 13 are not parallel to each other, the light L emitted from the first optical fiber 10 is emitted parallel to the optical axis direction of the first optical fiber 10 at the first lens 14. As a result, the light L is emitted from the first lens 14 towards the second lens 24 parallel to the axial direction D, thus suppressing optical coupling loss. When the refractive index of the first lens 14 is higher than that of the first optical fiber 10, the tilt angle of the first ferrule end face 13b relative to the plane orthogonal to the axial direction D is greater than the tilt angle of the first lens end face 14b relative to the plane orthogonal to the axial direction D. Furthermore, the second ferrule end face 23b of the second ferrule 23 opposite to the second lens 24 and the second lens end face 24b of the second lens 24 opposite to the second ferrule 23 may also be non-parallel to each other. In this case, the same effect as the first lens 14 and the first insert 13 mentioned above can be obtained.

[0053] Next, an example of the assembly method for fiber optic connection structure 1 will be explained. First, as... Figure 5 As shown, a first sleeve 5 for the first collimator 2, a first ferrule 13 for holding the first optical fiber 10, and a first lens 14 are prepared. The first lens 14 is inserted into the first sleeve 5 and fixed to the first sleeve 5 by adhesive. At this time, the first lens 14 is inserted into the interior of the first sleeve 5 in such a way that the end face 14c of the first lens 14 does not protrude from the end face 5b of the first sleeve 5.

[0054] Then, the first ferrule 13 is inserted into the first sleeve 5. The first ferrule 13 is inserted into the first sleeve 5 from the opposite side of the end face 14c of the first lens 14. At this time, the rotational position of the first ferrule 13 around the first optical fiber 10 is adjusted so that the tilt direction of the first ferrule end face 13b of the first ferrule 13 is consistent with the tilt direction of the first lens end face 14b of the first lens 14. After the first ferrule 13 is inserted into the first sleeve 5, the length of the gap S1 between the first lens 14 and the first ferrule 13 in the axial direction D is adjusted.

[0055] For example, such as Figure 6 As shown, a reflector M is disposed on the side of the first sleeve 5 opposite to the first optical fiber 10. The aforementioned adjustment of the gap S1 is performed by reflecting the light L emitted from the first lens 14 through the first optical fiber 10 by the reflector M, while detecting the power of the light L reflected back to the first optical fiber 10 at the reflector M. When the direction extending from the first optical fiber 10 along the axial direction D is defined as the Z direction, the direction orthogonal to the Z direction is defined as the X direction, and the direction orthogonal to both the Z and X directions is defined as the Y direction, for example, the reflector M can be tilted in the θx direction about the X direction and the θy direction about the Y direction.

[0056] To maximize the power of the light L collimated from the first fiber 10 through the first lens 14 and reflected at the reflector M, the gap S1 is adjusted. Alternatively, instead of adjusting the gap S1 using the reflector M, a beam analyzer can be positioned opposite the end face 14c of the first lens 14, and the gap S1 is adjusted while observing the light L through the beam analyzer. In this case, the gap S1 is adjusted so that the beam diameter of the light L emitted from the end face 14c of the first lens 14 is the desired beam diameter. After adjusting the gap S1 in the above manner, the first ferrule 13 is fixed to the first sleeve 5 with adhesive, and the first collimator 2 is completed.

[0057] like Figure 7 and Figure 8As shown, the first collimator 2 is fixed to the tubular component 4. At this time, the position of the tubular component 4 and the position of the first sleeve 5 in the direction orthogonal to the axial direction D (XY direction) are adjusted. That is, the position of the first sleeve 5 relative to the tubular component 4 in the XY direction is adjusted so that the position of the axis of the tubular component 4 is aligned with the position of the axis of the first sleeve 5. The XY direction position adjustment of the first sleeve 5 relative to the tubular component 4 can be performed by a pin-hole clamp P inserted into the tubular component 4. The pin-hole clamp P has a cylindrical insertion portion P1 into which the tubular component 4 is inserted and a flange portion P2 that expands from the insertion portion P1. A through hole P3 is formed in the pin-hole clamp P, through which the insertion portion P1 and the flange portion P2 pass in the axial direction D.

[0058] For example, the insertion part P1 of the pin-hole clamp P is inserted into the tubular component 4 from the opposite side of the first sleeve 5, so that the light L emitted from the first lens 14 through the first optical fiber 10 is adjusted to the position of the first sleeve 5 by passing through the through hole P3 of the pin-hole clamp P. After adjusting the position of the first sleeve 5 relative to the tubular component 4 by passing the light L through the through hole P3, the end face 5b of the first sleeve 5 is fixed to the first end 4b of the tubular component 4. Then, the pin-hole clamp P is disengaged from the tubular component 4. After the above steps, the fixation of the first collimator 2 relative to the tubular component 4 is completed. The fixation of the first sleeve 5 and the tubular component 4 can be achieved by adhesive bonding and various other fixing methods.

[0059] Next, as Figure 9 As shown, the second lens 24 is inserted into the tubular component 4 from the opposite side of the first collimator 2. At this time, the rotational position of the second lens 24 about the optical axis of the first optical fiber 10 is adjusted and fixed by adhesive. Then, as... Figure 10 As shown, the second sleeve 6, into which the second insert 23 is inserted, is installed at the second end 4c of the tubular component 4.

[0060] At this point, after aligning the second optical fiber 20 relative to the second lens 24 in the X, Y, Z directions and θz direction around the Z direction, the second ferrule 23 is fixed to the second sleeve 6 using adhesive. Furthermore, the second sleeve 6 is aligned relative to the tubular member 4 in the X and Y directions, and then the end face 6b of the second sleeve 6 is fixed to the second end 4c of the tubular member 4. Adhesion and various other fixing methods can be used to fix the second sleeve 6 and the tubular member 4.

[0061] After the above steps, the second collimator 3 is fixed relative to the tubular component 4. Adhesive is applied between the first sleeve 5 and the first insert 13, between the first sleeve 5 and the first lens 14, between the tubular component 4 and the second lens 24, and between the second sleeve 6 and the second insert 23. By applying adhesive to these areas, the thickness of the adhesive can be made thin.

[0062] The maximum thickness of the adhesive in the fiber optic connection structure 1 is, for example, 50 μm or less. "Maximum adhesive thickness" indicates the maximum thickness of the adhesive applied between multiple components for the purpose of fixing the components, filling the gaps between them. As an example, the lower limit of the maximum adhesive thickness is 5 μm. Alternatively, the maximum adhesive thickness can be 10 μm or more, or 20 μm or more. Furthermore, the maximum adhesive thickness can be 40 μm or less, or 30 μm or less. As mentioned above, the adhesive is, for example, a UV-curable adhesive. However, the adhesive can also be an adhesive other than a UV-curable one, for example, a visible light-curable adhesive, a thermosetting adhesive, or a room-temperature curing adhesive.

[0063] Next, the effects of the optical fiber connection structure 1 according to the embodiment will be explained. In the optical fiber connection structure 1, a first collimator 2 is installed at the first end 4b of the tubular member 4, and a second collimator 3 is installed at the second end 4c of the tubular member 4 opposite to the first end 4b. The first collimator 2 has a first sleeve 5, inside which a first lens 14 and a first ferrule 13 holding the first optical fiber 10 are held. The second collimator 3 has a second sleeve 6, inside which a second lens 24 and a second ferrule 23 holding the second optical fiber 20 are held. The first sleeve 5 is fixed to the first end 4b when the first lens 14 is facing the tubular member 4, and the second sleeve 6 is fixed to the second end 4c when the second lens 24 is inserted into the tubular member 4. Therefore, the first collimator 2 and the second collimator 3 are respectively fixed at the first end 4b and the second end 4c in the axial direction D of the tubular component 4, thus the first collimator 2 and the second collimator 3 can be easily fixed to the tubular component 4. The first sleeve 5 and the tubular component 4, and the second sleeve 6 and the second lens 24 can be fixed by adhesive and other various fixing methods.

[0064] Furthermore, the first collimator 2 and the second collimator 3 are fixed at the first end 4b and the second end 4c, respectively, thereby suppressing the tilt of the first ferrule 13 and the second ferrule 23 and improving the reliability of the optical connection. The outer diameter of the second ferrule 23 of the second collimator 3 is larger than the outer diameter of the second lens 24. Therefore, with the second lens 24 fixed to the tubular component 4, the second ferrule 23 can be aligned in a direction orthogonal to the optical axis of the second lens 24 (orthogonal to the axial direction D), thus facilitating alignment and component assembly.

[0065] like Figure 2 and Figure 4 As shown, the first lens 14 has a first lens end face 14b opposite to the first insert 13, and the first insert 13 has a first insert end face 13b opposite to the first lens 14. The tilt angle of the first lens end face 14b relative to a plane orthogonal to the axial direction D may differ from the tilt angle of the first insert end face 13b relative to a plane orthogonal to the axial direction D, allowing light L to be emitted from the first lens 14 toward the second lens 24 along the axial direction D. Thus, light L is emitted along the axial direction D of the tubular component 4, thereby suppressing beam distortion and further improving the reliability of optical coupling.

[0066] In this embodiment, the second lens 24 has a second lens end face 24b opposite to the second insert 23, and the second insert 23 has a second insert end face 23b opposite to the second lens 24. The tilt angle of the second lens end face 24b relative to a plane orthogonal to the axial direction D may differ from the tilt angle of the second insert end face 23b relative to a plane orthogonal to the axial direction D, allowing light to be emitted from the second lens 24 toward the first lens 14 in the axial direction D. In this case, similarly to the aforementioned case, beam distortion can be reduced, further improving the reliability of optical coupling.

[0067] In this embodiment, the end face 14c of the first lens 14 opposite to the tubular member 4 extends further into the first sleeve 5 than the end face 5b of the first sleeve 5 opposite to the tubular member 4. Therefore, the first lens 14 does not protrude from the first sleeve 5, and thus interference between the first lens 14 and the tubular member 4 can be avoided when the first collimator 2 is aligned in a direction orthogonal to the optical axis of the first lens 14 (e.g., the X and Y directions). Therefore, alignment and fixation of the first collimator 2 can be easily performed. Furthermore, at least one of the end face 14c of the first lens 14 opposite to the tubular member 4 and the end face 24c of the second lens 24 opposite to the tubular member 4 can be spherical.

[0068] In this embodiment, the maximum thickness of the adhesive is 50 μm. Therefore, the maximum thickness of the adhesive can be set to be thin, less than 50 μm, making it easier to fix the first collimator 2 and the second collimator 3, and further improving the reliability of the optical coupling.

[0069] Next, various variations of optical fiber connection structures will be described. Figure 11 This is a cross-sectional view showing the optical fiber connection structure 31 involved in the modified example. A portion of the structure of the optical fiber connection structure 31 is identical to the structure of a portion of the aforementioned optical fiber connection structure 1. Therefore, descriptions that are repeated in the description of optical fiber connection structure 1 will be appropriately omitted using the same reference numerals. In the optical fiber connection structure 31, an optical functional component 32 is disposed inside the tubular component 4. As an example, the optical functional component 32 is a Faraday element. In this case, the optical fiber connection structure 31 can function as an optical isolator.

[0070] Figure 12 It means and Figure 11 Cross-sectional views of fiber optic connection configuration 41 involved in various other variations. (As described above...) Figure 2 In fiber optic connection configuration 1, the outer diameter of the first ferrule 13 is different from the outer diameter of the second ferrule 23, and is smaller. In contrast, Figure 12 The fiber optic connection structure 41 shown replaces the aforementioned first ferrule 13, first lens 14, and first sleeve 5, and instead includes a first ferrule 43, first lens 44, and first sleeve 45 with an outer diameter substantially the same as that of the second ferrule 23. The inner diameter of the first sleeve 45 is larger than the inner diameter of the tubular component 4. The outer diameter of the first lens 44 is larger than both the inner diameter of the tubular component 4 and the outer diameter of the second lens 24.

[0071] The second ferrule 23 replaces the aforementioned second optical fiber 20 and instead retains the two-core second optical fiber 20A. Furthermore, in Figure 12 For simplicity, the illustration of the 2-core configuration has been omitted. Furthermore, an optical functional component 42 is disposed inside the tubular component 4. The optical functional component 42 is, for example, a WDM filter. In this case, the fiber optic connection configuration 41 can be configured as a WDM multiplexing / splitting device. Moreover, the example shown above is a second fiber 20A with 2 cores. However, any fiber with 2 cores, whether the first or second fiber, is acceptable; for example, the first fiber 10 could also be a 2-core fiber.

[0072] Figure 13 This is a perspective view showing the optical fiber connection structure 51 involved in other variations. Figure 14 This is a cross-sectional view showing the fiber optic connection structure 51. (Example) Figure 13 and Figure 14As shown, the optical fiber connection structure 51 has a first collimator 62, a second collimator 63, and a tubular component 4. In the first collimator 62, the first ferrule 13 holds a multi-core optical fiber 60, and in the second collimator 63, the second ferrule 23 holds a multiple single-core optical fiber 65.

[0073] like Figure 15 As shown, for example, the single-core fiber 65 is a TEC (Thermally Expanded Core) fiber. The single-core fiber 65, for example, has a beam amplification section 68 capable of expanding the mode field diameter of the light transmitted through the fiber core 67. The beam amplification section 68 is, for example, a core amplification section that expands the core diameter of the fiber core 67 at the end face 66 opposite to the second lens 24. For example, the beam amplification section 68 includes a tapered portion 68b that expands the fiber core 67 in a tapered shape. In this case, the fiber core 67 is expanded at the end face 66, thereby expanding the mode field diameter of the light transmitted within the single-core fiber 65 in the beam amplification section 68 in a direction orthogonal to the axial direction D.

[0074] In the modified optical fiber connection structure 51 described above, the first optical fiber is a multi-core optical fiber 60, and the second optical fiber is a plurality of single-core optical fibers 65. Each of the plurality of single-core optical fibers 65 has a beam amplification section 68 that can amplify the mode field diameter of light transmitted within the core 67 of the single-core optical fiber 65. Thus, the optical fiber connection structure 51 can be configured as a fan-in / fan-out device for the multi-core optical fiber 60.

[0075] Figure 16 This is a cross-sectional view showing the fiber optic connection structure 71 involved in other variations. For example... Figure 16 As shown, the fiber optic connection structure 71, for example, constitutes a lens-coupled multi-core fiber fan-in / fan-out (FIFO) device. The fiber optic connection structure 71 includes a multi-core fiber 80, a plurality of single-core fibers 90, a first lens 70A sandwiched between the multi-core fiber 80 and the plurality of single-core fibers 90, and a second lens 70B sandwiched between the plurality of single-core fibers 90 and the first lens 70A.

[0076] The multi-core optical fiber 80 has a cladding 82 and multiple cores 81, while each single-core optical fiber 90 has a core 91 and a cladding 92. Furthermore, in Figure 16 For simplicity, the diagrams of fiber cores 81 and 91 are shown as lines. Multiple single-core optical fibers 90 are bundled together by a second ferrule 93. Multi-core optical fibers 80 are held in place by a first ferrule 83. Each multi-core optical fiber 80 has a first end face 84 opposite to the first lens 70A. For example, the first end face 84 is flat and inclined relative to a plane orthogonal to the axial direction D. Each single-core optical fiber 90 has a second end face 94 opposite to the second lens 70B. The second end face 94 is similarly flat to the first end face 84 and inclined relative to a plane orthogonal to the axial direction D.

[0077] The first lens 70A is positioned opposite the multi-core optical fiber 80 along the axial direction D. The first lens 70A focuses the multiple beams L emitted from each of the multiple cores 81 of the multi-core optical fiber 80 on the opposite side of the multi-core optical fiber 80. The second lens 70B is positioned opposite the single-core optical fiber 90 along the axial direction D.

[0078] Both the first lens 70A and the second lens 70B are GRIN lenses. For example, the second lens 70B may be a GRIN lens that functions as a beam amplification section. An anti-reflective (AR) coating may be applied between the first lens 70A and the first end face 84, or a small gap may be created. Additionally, an adhesive (for example, a gel-like adhesive) may be sandwiched between the first lens 70A and the first end face 84. The same applies to the area between the second lens 70B and the second end face 94. The above... Figure 16 An example of a first lens 70A and a second lens 70B being a GRIN lens has been described. However, it is sufficient if at least one of the first lens 70A and the second lens 70B is a GRIN lens. As described above, GRIN lenses can also be used as the first lens and the second lens.

[0079] The embodiments and variations of the optical fiber connection structure according to the present invention have been described above. However, the present invention is not limited to the foregoing embodiments or variations. That is, the present invention can be modified and altered in various ways within the scope of the claims, which will be readily apparent to those skilled in the art. For example, the shape, size, material, quantity, and arrangement of the various parts of the optical fiber connection structure can be appropriately changed within the scope of the above-described scope.

[0080] Explanation of the label

[0081] 1, 31, 41, 51, 71… Fiber optic connection structure

[0082] 2. 62...1st collimator

[0083] 3. 63…2nd collimator

[0084] 4… tubular components

[0085] 4b…First end

[0086] 4c… second end

[0087] 5, 45… First Sleeve

[0088] 5b…end face

[0089] 6…Second sleeve

[0090] 6b…end face

[0091] 10…First fiber

[0092] 13, 43, 83… First ferrule

[0093] 13b…First ferrule end face

[0094] 14, 44, 70A… Lens 1

[0095] 14b…First lens end face

[0096] 14c…end face

[0097] 20, 20A…Second fiber

[0098] 23, 93…Second ferrule

[0099] 23b…Second ferrule end face

[0100] 24, 70B…Second Lens

[0101] 24b…Second lens end face

[0102] 24c…end face

[0103] 32, 42… optical functional components

[0104] 60, 80… multi-core optical fiber (first fiber)

[0105] 65, 90… single-core optical fiber (second fiber)

[0106] 66…end face

[0107] 67…core

[0108] 68… Beam Enlargement Section

[0109] 68b…cone

[0110] 81…core fiber

[0111] 82…cladding

[0112] 84…First end face

[0113] 91…core fiber

[0114] 92…cladding

[0115] 94…Second end face

[0116] D…axis direction

[0117] L…light

[0118] M…reflector

[0119] P…Pin Hole Fixture

[0120] P1…Insert section

[0121] P2…Flange

[0122] P3…through hole

[0123] S1, S2... gaps

[0124] S2…gap

Claims

1. An optical fiber connection structure, comprising: tubular components; The first collimator is mounted at the first end in the axial direction of the tubular component; and The second collimator is installed at the second end of the tubular component, opposite to the first end. The first collimator includes a first optical fiber, a first ferrule holding the first optical fiber, a first lens opposite to the first ferrule with a gap, and a first sleeve holding the first lens and the first ferrule inside. The second collimator includes a second optical fiber, a second ferrule for holding the second optical fiber, a second lens opposite to the second ferrule with a gap, and a second sleeve for holding the second lens and the second ferrule inside. The first lens is a front spherical rod lens or a GRIN lens. The second lens is a front spherical rod lens or a GRIN lens. The outer surface of the first insert and the inner surface of the first sleeve, the outer surface of the first lens and the inner surface of the first sleeve, the outer surface of the second lens and the inner surface of the tubular component, and the outer surface of the second insert and the inner surface of the second sleeve are respectively fixed by adhesive. With the first lens facing the tubular component, the first sleeve is fixed to the first end; with the second lens entering the tubular component, the second sleeve is fixed to the second end. The ends of the first sleeve and the first end of the tubular component, and the ends of the second sleeve and the second end of the tubular component are respectively fixed by adhesive. The second lens has a second lens end face opposite to the second ferrule. The end face of the second lens protrudes from the tubular component. The end face of the first lens, opposite to the tubular component, extends further into the first sleeve than the end face of the first sleeve, which is also opposite to the tubular component. The outer diameter of the second ferrule is larger than the outer diameter of the second lens. The first optical fiber is a multi-core optical fiber. The second optical fiber consists of multiple single-core optical fibers. Each of the plurality of single-core optical fibers has a beam amplification section capable of expanding the mode field diameter of light transmitted within the core of the single-core optical fiber. Multiple light beams are transmitted between the first lens and the second lens inside the tubular component.

2. The optical fiber connection structure according to claim 1, wherein, The first lens has a first lens end face opposite to the first ferrule. The first insert has a first insert end face opposite to the first lens. The tilt angle of the first lens end face relative to a plane orthogonal to the axial direction is different from the tilt angle of the first ferrule end face relative to a plane orthogonal to the axial direction. Light is emitted from the first lens toward the second lens along the axis.

3. The optical fiber connection structure according to claim 1 or 2, wherein, The second insert has a second insert end face opposite to the second lens. The tilt angle of the second lens end face relative to the plane orthogonal to the axial direction is different from the tilt angle of the second ferrule end face relative to the plane orthogonal to the axial direction. Light is emitted from the second lens toward the first lens along the axis.

4. The optical fiber connection structure according to claim 1 or 2, wherein, It has Faraday elements arranged inside the tubular component.

5. The optical fiber connection structure according to claim 1 or 2, wherein, Either the first optical fiber or the second optical fiber is a 2-core optical fiber. It has a WDM filter configured inside the tubular component.

6. The optical fiber connection structure according to claim 1 or 2, wherein, The maximum thickness of the adhesive is less than 50 μm.

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