Optical connection structure and optical transceiver module equipped therewith

Abstract

This disclosure aims to reduce the size of optical components that perform fan-in / fan-out operations for multicore fibers. [Solution] The present disclosure provides an optical connection structure comprising a multicore fiber, a plurality of optical fibers corresponding to each core of the multicore fiber, and an optical component having a plurality of GRIN lenses connecting each core of the multicore fiber to the plurality of optical fibers, wherein the plurality of GRIN lenses are in contact with each other in a surface area.

Description

[[Technical Field]]

[0001] The present disclosure relates to an optical component that performs fan-in / fan-out for multi-core fibers. [[Background Art]]

[0002] To achieve FIFO (Fan-in-Fan-out) of connecting each core of a multi-core fiber to an optical device such as an optical fiber, the following methods have been proposed: a method of bundling and connecting reduced-diameter fibers, a method of connecting fibers by melt-drawing, and a method of spatial coupling (see, for example, Non-Patent Document 1). [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Patent No. 7360694 [[Non-Patent Documents]]

[0004] [[Non-Patent Document 1]] Hideyuki Nasu, Satoshi Ide, Fumio Koyama, "Data Center Optical Interconnection Technology", IEICE Transactions, Vol.106, No.2, pp.106-113 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] Conventional optical components including those described in Non-Patent Document 1 all have the problem of increased component size. An object of the present disclosure is to reduce the size of an optical component that performs fan-in / fan-out for multi-core fibers. [[Means for Solving the Problem]]

[0006] Specifically, the optical connection structure of the present disclosure includes: a multi-core fiber, a plurality of optical fibers respectively corresponding to each core of the multi-core fiber, an optical component comprising a plurality of GRIN lenses that connect each core of the multicore fiber to the plurality of optical fibers, comprising: wherein the plurality of GRIN lenses are in surface contact with each other, and a boundary surface between the plurality of GRIN lenses is a flat surface parallel to the central axes of the plurality of GRIN lenses.

[0007] A lens length of each of the plurality of GRIN lenses is 1 / 2 pitch or an integer multiple of 1 / 2 pitch.

[0008] The multicore fiber may include a core on a central axis of the multicore fiber. In this aspect, the plurality of GRIN lenses may include a GRIN lens that connects a core arranged on the central axis of the multicore fiber to an optical fiber. Further, the plurality of GRIN lenses may include an optical waveguide that connects a core arranged on the central axis of the multicore fiber to an optical fiber.

[0009] An optical transceiver module according to the present disclosure includes: the optical connection structure according to the present disclosure; an optical transmitter that outputs signal light to the plurality of optical fibers included in the optical connection structure, and an optical receiver that receives signal light from the plurality of optical fibers included in the optical connection structure, comprising the above.

[0010] Note that the above disclosures can be combined as much as possible.

Effects of the Invention

[0011] According to the present disclosure, an optical component for performing fan-in / fan-out of a multicore fiber can be reduced in size.

Brief Description of Drawings

[0012] [Figure 1]This is an example of an embodiment of the optical connection structure of the present disclosure, where (a) shows the end faces of multiple optical fibers, (b) shows a top view of the optical connection structure, and (c) shows the end face of a multicore fiber. [Figure 2] This disclosure shows an example of an embodiment of the optical connection structure. [Figure 3] This disclosure shows an example of an embodiment of the optical connection structure. [Figure 4] An example of a cross-sectional configuration of a conventional optical connection structure is shown. [Figure 5] This disclosure shows an example of an embodiment of the optical connection structure. [Figure 6] This is an explanatory diagram of the joint surface. [Figure 7] This disclosure shows an example of an embodiment of the optical connection structure. [Figure 8] This disclosure shows an example of an embodiment of the optical connection structure. [Figure 9] This disclosure shows an example of an embodiment of the optical transceiver module. [Modes for carrying out the invention]

[0013] Embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments shown below. These examples are illustrative, and this disclosure can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. In this specification and in the drawings, components with the same reference numerals refer to the same components.

[0014] Figure 1 shows an example of an embodiment of the optical connection structure of the present disclosure. The optical component 92 in this embodiment is a fan-in / fan-out component for a multicore fiber 93. The principle of the optical component 92 is the same as that of Patent Document 1. Specifically, the optical connection structure of this embodiment is Multicore fiber 93 and A plurality of optical fibers 91 corresponding to each core 31 of the multicore fiber 93, An optical component 92 comprising each core 31 positioned at a location other than the central axis of the multicore fiber 93 and a plurality of GRIN lenses 21 that connect the plurality of optical fibers 91, comprising:

[0015] The lens length of the GRIN lens 21 is 1 / 2 pitch or an integer multiple of 1 / 2 pitch. Although FIG. 1 shows an example where one optical component 92 has this lens length, the present disclosure is not limited thereto. For example, as shown in FIG. 2, it may be a combination of GRIN lenses 21-1 and 21-2 each having 1 / 4 pitch or an integer multiple of 1 / 4 pitch. Further, as shown in FIG. 3, a spacer 94 may be disposed between the GRIN lenses 21-1 and 21-2. The same applies to the following embodiments.

[0016] Further, in the following embodiments, an example is shown in which the connection destinations of a plurality of cores of the multi-core fiber 93 are a plurality of optical fibers 91, but the present disclosure may have any configuration that can function as a plurality of optical waveguides. For example, the plurality of optical fibers 91 may be one or more optical connectors, may be a plurality of optical waveguides provided in an optical circuit, or may be a plurality of terminals provided in an optical device such as a light source.

[0017] FIG. 4 shows an example of a cross-sectional configuration of a conventional optical component 192. The GRIN lens 121 itself is a cylindrical optical component. Therefore, when attempting to connect individual GRIN lenses 121 to each core 31 of the multi-core fiber 93, the diameter φ of the GRIN lens 121 g is limited by the spacing D between the cores 31 m .

[0018] The distance from the central axis 32 of the multi-core fiber 93 to the core 31 is the spacing D between the cores 31 m can be expressed as D m / √2. Further, the distance from the central axis 32 of the multi-core fiber 93 to the central axis of the GRIN lens 121 is the diameter φ of the GRIN lens 121 g can be expressed as φ g / √2. Then, the optical path conversion amount (shift amount) D d can be expressed by the following formula. (Formula 1) D d =2*(φ g / √2-Dm / √2) (Equation 1)

[0019] The core 31 of the multicore fiber 93 must be located within the GRIN lens 121. Therefore, if L is the distance from the central axis 32 of the multicore fiber 93 to the GRIN lens 121, the following equation must be satisfied. (Math 2) D m / √2>L(Equation 2)

[0020] Here, the distance L from the central axis 32 of the multicore fiber 93 to the GRIN lens 121 can be expressed by the following equation. (Math 3) L = φ g / √2-φ g / 2 (formula 3)

[0021] From equations 2 and 3, the GRIN lens diameter φ g and the distance D between core 31 m The following equation is satisfied. (Math 4) φ g < √2 / (√2 + 1) D m (Formula 4)

[0022] From equations (1) and (4), the following equation is obtained. (Math 5) D d <2*((√2+1)D m -D m / √2) D d < 2* ( √2+1 (-1 / √2)*D m (Formula 5)

[0023] From equation (5), the optical path conversion amount (shift amount) D d The spacing D of core 31 m It can be seen that it is limited to the diameter φ of the GRIN lens 121. gAs the value decreases, the amount of shift in the optical path conversion by the GRIN lens 121 decreases. Therefore, the spacing D of the cores 31 of the multicore fiber 93 m This presents a problem: it becomes impossible to widen the gap to the spacing of the optical fibers 91 using the cylindrical GRIN lens 121, making it difficult to manufacture the optical component 192.

[0024] (First Embodiment) Figure 5 shows an example of an embodiment of the optical component 92 of the present disclosure. In this embodiment, the optical component 92 has multiple GRIN lenses 21 that interact with each other at an interface S AB S BC S CD S DA They are in contact at the interface. In this embodiment, an example is shown in which a multicore fiber 93 is equipped with four GRIN lenses 21A, 21B, 21C, and 21D. In this embodiment, the four GRIN lenses 21A, 21B, 21C, and 21D are in contact at the interface S AB S BC S CD S DA They are in contact at the interface S. AB S BC S CD S DA This includes the central axis 32 of the multicore fiber 93. Hereafter, when GRIN lenses 21A, 21B, 21C, and 21D are not distinguished, they will be referred to as GRIN lens 21.

[0025] Figure 6 shows an explanatory diagram of the interface. Each interface S AB S BC S CD S DA This is a flat surface obtained by cutting the side surface of the cylindrical GRIN lenses 21A, 21B, 21C, and 21D with a plane parallel to the central axis of the GRIN lenses 21A, 21B, 21C, and 21D. For example, the interface S AB This is a flat surface S obtained by cutting the side of the cylindrical GRIN lens 21A with a plane parallel to the central axis. A2 And a flat surface S obtained by cutting the side of the cylindrical GRIN lens 21B with a plane parallel to the central axis. B1This is the bonding surface. When GRIN lenses 21A, 21B, 21C, and 21D are joined, the GRIN lens 21 is cut so that its central axis is located midway between core 11 and core 31.

[0026] When the optical component 92 is connected to the multicore fiber 93, the interface S AB S BC S CD S DA The four GRIN lenses 21A, 21B, 21C, and 21D are joined together after cutting so that the central axis 32 of the multicore fiber 93 passes through it. This connects the optical component 92 and the multicore fiber 93 so that their central axes coincide, allowing light from the four cores 31 of the multicore fiber 93 to be incident on the GRIN lenses 21A, 21B, 21C, and 21D at the appropriate positions.

[0027] In this embodiment, the cross-sections of the multiple GRIN lenses 21 can be made flat, allowing each GRIN lens 21 to be joined easily and accurately. Furthermore, by cutting the side surface of the GRIN lens 21 parallel to the central axis as shown in Figure 6 at the base material stage, joining them into the shape shown in Figure 5, and performing melt stretching, an optical component 92 with multiple GRIN lenses 21 precisely arranged can be efficiently manufactured. In this embodiment, quartz GRIN lenses 21 are used, and the interface S AB S BC S CD S DA A glass material with a lower refractive index than quartz may be provided.

[0028] Figures 1 to 3 show examples where multiple GRIN lenses 21 are surrounded by capillaries 22, but the disclosure is not limited thereto. In this embodiment, the arrangement of the multiple GRIN lenses 21 is fixed even without capillaries 22 surrounding them, because the cross-sections of the multiple GRIN lenses 21 are joined together.

[0029] Furthermore, in this disclosure, the diameter of the GRIN lens 21 is φ gSince the limitations are removed, it becomes possible to fabricate an optical component 92 to which the core 31 of the multicore fiber 93 can be connected at the position indicated by reference numeral 11 in Figure 5.

[0030] Alternatively, as shown in Figure 7, instead of the optical fiber 91, the core 31 of the multicore fiber 93 may be connected to the waveguide 51 of the optical waveguide circuit 95. In this configuration, a GRIN lens 24 with a 1 / 4 pitch or an integer multiple of a 1 / 4 pitch may be provided between the waveguide 51 and the GRIN lens 21. This allows the numerical aperture to be converted using the GRIN lens 24.

[0031] As described above, the optical component 92 of this embodiment uses the GRIN lens 21 to adjust the spacing D of the cores 31 of the multicore fiber 93. m This realizes a pitch conversion function. In this disclosure, the lens diameter of the GRIN lens 21 can be increased, so the spacing D of the core 31 that can be converted using the GRIN lens 21 is m This greatly expands the degree of freedom.

[0032] (Second embodiment) In the embodiments described above, an example was shown in which the optical component 92 is provided with four GRIN lenses, but the disclosure is not limited thereto. For example, as shown in Figure 8, the optical component 92 may be formed by joining six GRIN lenses 21. These interfaces also include the central axis of the multicore fiber 93. This enables fan-in and fan-out of the 6-core multicore fiber 93.

[0033] The six GRIN lenses 21 may be equipped with a component 23 at their center for propagating light from the cores positioned along the central axis of the multicore fiber 93. This also enables fan-in and fan-out for the 7-core multicore fiber 93.

[0034] Component 23 can employ any configuration that allows light incident on component 23 to enter the optical fiber 91 when it exits from component 23. For example, a GRIN lens similar to the one shown in Figures 1 to 3 can be used. Also, component 23 has a core spacing D m Since there is no need for conversion, it is also possible to use optical waveguides such as optical fibers.

[0035] As described above, in this embodiment, the optical component 92 cuts the side surface of the GRIN lens 21 in accordance with the number of cores of the multicore fiber 93 using a plane parallel to the central axis of the GRIN lens 21, and joins them together, thereby enabling fan-in and fan-out of the multicore fiber 93.

[0036] (Third embodiment) Figure 9 shows an example of applying the optical component 92 to an optical transceiver module. As shown in Figures 1 to 3, two optical components 92 are used to connect each core 31 of a 4-core multicore fiber 93 to an 8-core optical fiber 91, and the optical fiber 91 is connected in groups of four to an optical transmitter 96 and an optical receiver 97. The optical transmitter 96 outputs signal light to the optical fiber 91. The optical receiver 97 receives signal light from the optical fiber 91. This allows for the configuration of an optical transceiver with a multicore fiber 93 connected.

[0037] By employing the optical component 92 disclosed herein, as is clear from the structures shown in Figures 1 to 3, the component volume can be reduced to less than 1 / 10 of that of conventional products, allowing it to be housed within an optical transceiver module. Furthermore, optical loss from the multicore fiber 93 to its destination is extremely low, thereby preventing heat generation. In addition, since the optical path between the multicore fiber 93 and its destination can be formed using only quartz glass, extremely stable communication can be achieved even underwater. [Explanation of Symbols]

[0038] 11, 31: Core 12: Clad 21, 24, 21-1, 21-2, 21A, 21B, 21C, 21D, 121: GRIN lenses 22, 22-1, 22-2, 122: Capillary 23: Components 91: Fiber Optic 92: Optical components 93: Multicore fiber 94: Spacer 95: Optical waveguide circuit 96: Optical Transmitter 97: Light receiver

Claims

1. Multicore fiber and Multiple optical fibers corresponding to each core of the multicore fiber, An optical component that connects each core of the multicore fiber to the plurality of optical fibers on a one-to-one basis, Equipped with, The optical component comprises a plurality of GRIN lenses equal to the number of cores in the multicore fiber, The lens central axes located at the center of the virtual circles of the plurality of GRIN lenses are each positioned midway between the optical axis of the core of the corresponding multicore fiber and the optical axis of the core of the optical fiber. In the overlapping region of the virtual circles of the plurality of GRIN lenses, the plurality of GRIN lenses are in contact with each other in a surface, The interface of the plurality of GRIN lenses is a flat surface parallel to the lens central axis of the plurality of GRIN lenses. The GRIN lens diameter φ g of the plurality of GRIN lenses and the distance D m between the cores of the multicore fiber satisfy the following equation: φ g ≧√2 / (√2+1)D m Optical connection structure.

2. A multicore fiber having a core on its central axis, Multiple optical fibers corresponding to each core of the multicore fiber, An optical component that connects each core of the multicore fiber to the plurality of optical fibers on a one-to-one basis, Equipped with, The optical component comprises a plurality of GRIN lenses equal to the number of cores in the multicore fiber, The plurality of GRIN lenses include a first GRIN lens that connects the core located on the central axis of the multicore fiber to the optical fiber. Among the plurality of GRIN lenses, each GRIN lens different from the first GRIN lens is connected to a position different from the core of the corresponding multicore fiber and the core of the optical fiber. The plurality of GRIN lenses are in contact with each other on a surface, The interface of the plurality of GRIN lenses is a flat surface parallel to the lens central axis of the plurality of GRIN lenses. Optical connection structure.

3. The lens central axes of the plurality of GRIN lenses are each positioned midway between the optical axis of the core of the corresponding multicore fiber and the optical axis of the core of the optical fiber, The optical connection structure according to claim 2.

4. The lens lengths of the plurality of GRIN lenses are 1 / 2 pitch or an integer multiple of 1 / 2 pitch. The optical connection structure according to claim 1 or 2.

5. An optical connection structure according to any one of claims 1 to 3, An optical transmitter that outputs signal light to the plurality of optical fibers provided in the optical connection structure, An optical receiver that receives light from the plurality of optical fibers provided in the optical connection structure, An optical transceiver module equipped with the following features.

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