Optical circuit mounting substrate, computer, multi-core optical ferrule, and optical connection method
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HAKUSAN INC
- Filing Date
- 2025-03-26
- Publication Date
- 2026-08-05
Smart Images
Figure 0007901205000001 
Figure 0007901205000002 
Figure 0007901205000003
Abstract
Description
Technical Field
[0001] The present invention relates to a manufacturing method of a multi-core optical ferrule for optically connecting optical fibers of an optical cable that transmits optical signals, an optical circuit mounting substrate provided with the multi-core optical ferrule, a computer, and an optical connection method.
Background Art
[0002] Optical cables using optical fibers are widely used for information communication in homes and industries because they enable high-speed communication of a large amount of information. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-108867), high accuracy is required for the diameter of the optical fiber hole, the diameter of the guide pin hole, the distance between the centers of the left and right guide pin holes, and the position of each optical fiber hole with respect to the midpoint between the line segments connecting the centers of the left and right guide pin holes. When plastic molding the ferrule, if the required accuracy for these is not satisfied, it must be discarded as a defective product, resulting in a decrease in the manufacturing yield. However, it does not disclose how to solve the problem that as the number of fiber holes increases, the ferrule warps and eccentricity of the positions of the fiber holes occurs.
[0003] The ferrule for a multi-core optical connector described in Patent Document 1 is a plastic ferrule for a multi-core optical connector of a fitting pin alignment method in which guide pin holes are formed on both the left and right sides of a plurality of horizontally arranged optical fiber holes, and the middle part between the left and right guide pin holes is made thin and vertically symmetric.
[0004] Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-86069) discloses a multi-core optical ferrule, a multi-core optical connector, and an optical module using these, which can utilize a housing for an MT connector and are easy to mold with high precision for 16 cores or more. The multi-core optical ferrule described in Patent Document 2 is a multi-core optical ferrule having multiple optical fiber insertion holes and two guide pin holes, wherein the optical fiber insertion holes consist of 16 or more holes arranged in a row in parallel, and the external shape and guide pin holes of the multi-core optical ferrule are configured to be the same shape and arrangement as the MT ferrule specified in IEC60874-16.
[0005] Patent Document 3 (Japanese Patent Publication No. 2007-286354) discloses an optical connector that prevents PC connection interference caused by poor end face angle of opposing ferrule tip faces due to protrusions formed on the obliquely polished surface of the ferrule.
[0006] The optical connector described in Patent Document 3 is an optical connector in which a pair of ferrules, each having a guide pin guide hole drilled in the longitudinal direction of the ferrule and an obliquely polished tip surface, are pressed and held together so that their obliquely polished surfaces are in close contact, and a recess is formed on the edge of the guide pin guide hole exposed on the obliquely polished surface.
[0007] Patent document 4 (Japanese Patent Publication No. 2012-194481) discloses an optical connector that can perform optical connection with low loss by compensating for variations in the amount of fiber protrusion between optical fibers, even without a polishing process on the end face of the optical connector.
[0008] The optical connector described in Patent Document 4 includes a fiber holding portion having a plurality of guide holes for guiding a plurality of optical fibers, a space connecting the plurality of guide holes and housing a plurality of optical fibers, and a deformable member that constitutes at least a part of the fiber holding portion and deforms the space to cause a portion or all of the plurality of optical fibers to bend within the space.
[0009] Patent Document 5 (Japanese Patent Publication No. 5-60949) discloses a multi-core optical connector that allows switching from the main line to the backup line (or vice versa) simply by reversing one of a pair of multi-core optical connectors that are connected, and since there is no need to match the core wires of the main line and the backup line, the line switching can be performed in an extremely short time.
[0010] The multi-core optical connector described in Patent Document 5 has two rows of insertion holes, each with the same number of optical fiber insertion holes arranged at the same pitch, between two parallel pin holes into which guide pins are inserted. These rows are arranged symmetrically with respect to a plane P containing the central axis of the two pin holes, and also symmetrically with respect to a plane Q perpendicular to the plane P that passes through the center of the two pin holes. [Prior art documents] [Patent Documents]
[0011] [Patent Document 1] Japanese Patent Publication No. 2001-108867 [Patent Document 2] Japanese Patent Publication No. 2004-86069 [Patent Document 3] Japanese Patent Publication No. 2007-286354 [Patent Document 4] Japanese Patent Publication No. 2012-194481 [Patent Document 5] Japanese Patent Application Publication No. 5-60949 [Overview of the project] [Problems that the invention aims to solve]
[0012] The optical connectors or optical connector ferrules described in the above-mentioned Patent Documents 1 to 4 disclose techniques for improving dimensional accuracy and enhancing properties such as mechanical strength.
[0013] In particular, Patent Document 2 discloses an optical connector that prevents light from conducting between optical fibers even when incorrectly connected to an MT connector. Therefore, the optical connector described in Patent Document 2 is not compatible with other connectors. Furthermore, Patent Document 5 discloses a multi-core optical connector in which two rows of optical fiber insertion holes are provided symmetrically with respect to a plane perpendicular to a plane P passing through the center of two pin holes. This multi-core optical connector is designed to be switched between using one end for the main line and the other for the backup line, and therefore has a lower connection density compared to existing connectors, and the pitch in the central part is not doubled, resulting in no connection compatibility. Furthermore, in recent years, there has been a growing demand for high-density mounting and space-saving solutions for ultra-small connectors. Additionally, compatibility with existing MPO (Multi-Fiber Push On) connectors is also becoming increasingly important.
[0014] The objective of the present invention is to provide a multi-core optical ferrule and a multi-core optical connector that enable low loss and high density even in optical fibers with a cladding diameter of 80 μm, and that are compatible with conventional optical connectors. Another object of the present invention is to provide a multi-core optical ferrule and a multi-core optical connector that enable high-density, high-speed, and high-capacity communication while maintaining connection compatibility with conventional optical connectors. Another object of the present invention is to provide multi-core optical ferrules and multi-core optical connectors that have low connection loss and low quality variation, even in optical fibers with a cladding diameter of 80 μm. [Means for solving the problem]
[0015] (1) A multi-core optical ferrule conforming to a single plane comprises a body made of a resin composition, multiple optical fiber insertion holes provided in the body into which optical fibers are inserted, and two guide pin holes provided in the body into which guide pins are inserted. The optical fiber insertion holes consist of 24 or more, arranged on a straight line connecting two of the guide pin holes, and the optical fiber insertion holes have a small diameter section and a large diameter section, with an inner diameter of 81 μm, and the pitch Pm in the central part of the optical fiber insertion holes is twice the pitch P of the optical fiber insertion holes other than the central part.
[0016] The cladding diameter of currently used optical fibers is 125 μm, and the outer diameter of the protective coating is 250 μm. To increase communication density, 12-core optical ferrules, which connect 12 optical fibers in a tape-like structure, are currently the most commonly used multi-core optical fibers. To connect these 12-core optical ferrules, multi-core optical ferrules with an optical fiber pitch of 250 μm are used as the standard. Furthermore, to achieve high-density information communication by increasing the number of optical fibers, a 24-core multi-optical ferrule has been developed in which 12 optical fibers are arranged in two rows with a pitch of 250 μm. In addition, a 16-core multi-optical ferrule has been developed in which 16 optical fibers are bundled together, with multiple optical fibers arranged in a single row with a pitch of 250 μm. Moreover, in recent years, optical fibers with coating thicknesses of 200 μm or 180 μm are being developed for even higher density packaging, and in this case, a 16-core optical fiber tape with a pitch of 200 μm is also being considered.
[0017] On the other hand, in recent years there has been a demand for even higher density and faster capacity in communications, and further multi-core applications are being considered, such as increasing the cladding diameter of optical fibers to 80 μm. This is particularly necessary because, in order to use optical fibers not only for long-distance communications but also as optical wiring on circuit boards inside computers such as servers, it is necessary to perform communications at higher density, speed, and capacity than ever before in confined environments. However, when connecting 24 cores by arranging 12 bundles of 80 μm cladding optical fibers in two rows, it becomes difficult to achieve high precision due to the structure of the molding die, resulting in a problem of high connection loss. Furthermore, this leads to a problem where the variability in product quality increases as the number of optical fibers increases. Furthermore, if the bundle of 12 optical fibers is in one row, CH1 to CH12 are in the same row, so by reversing the connector on one side, it is possible to connect the same CH. However, if the bundle of 12 optical fibers is in two rows, CH1 and CH13 will be connected, resulting in unstable optical characteristics.
[0018] Therefore, in the present invention, an optical fiber with an outer diameter of 80 μm is arranged in a single row to improve the positional accuracy of each optical fiber, and the pitch Pm at the center of the optical fiber insertion hole is designed to be twice the pitch P of the optical fiber insertion holes other than the center. Thus, a multi-core optical ferrule is developed with the aim of enabling low-loss and high-density mounting while having connection compatibility with conventional connectors. That is, according to the multi-core optical ferrule of the present invention, by setting the pitch P to 1 / 2 of the conventional standard, the optical fibers numbered odd from the center can communicate directly using the conventional standard communication method, while the optical fibers numbered even from the center located between them can perform high-density communication as newly added optical fibers. In this case, the newly added optical fibers may communicate using the conventional standard communication method or a communication method different from the conventional standard. For example, in the added optical fibers, the communication density can be doubled by communicating using the conventional standard method, and more than twice the amount of information can be communicated by communicating using a new standard such as high-frequency and multiplex communication. In this way, a multi-core optical ferrule can be obtained that has connection compatibility with multi-core optical ferrules of existing standards and enables high-speed and high-density mounting between multi-core optical ferrules of the present invention. Therefore, it also becomes easy to connect existing optical fibers for long-distance communication and optical fibers mounted on a substrate.
[0019] In this way, according to the present invention, while using an optical fiber with a cladding diameter of 80 μm, a multi-core optical ferrule can be obtained that achieves low loss and high density while also having connection compatibility with conventional standards. Furthermore, when there are 12 bundles of optical fibers arranged in two rows, connecting the connector in reverse results in the connection of CH1 and CH13. However, according to the present invention, since all CHs are in a single row, connections can be made with the same CH, and the optical characteristics can be stabilized.
[0020] By setting the inner diameter of the small-diameter portion to 81 μm, a slight clearance of 0.5 μm in radius is created between the optical fiber with a cladding diameter of 80 μm. Therefore, an adhesive can be filled here to securely fix the ferrule while precisely ensuring the positional accuracy of the optical fiber connection end face. That is, when attaching and fixing an optical fiber to a multi-core optical ferrule, an adhesive is filled on the large-diameter portion side of the optical fiber insertion hole, and the optical fiber is inserted. Then, the adhesive is pushed into the small-diameter portion together with the inserted optical fiber, and the adhesive fills the clearance with a radius of 0.5 μm within the small-diameter portion. When the adhesive hardens and shrinks, the central axis of the small-diameter portion 110 of the optical fiber insertion hole 103 can be precisely aligned with the central axis of the optical fiber.
[0021] (2) The multi-core optical ferrule according to the second invention is the multi-core optical ferrule according to an aspect of the invention, in which 24 optical fiber insertion holes may be provided and the pitch P may be 125 μm.
[0022] Thereby, it can have high connection compatibility with a general-purpose multi-core optical ferrule. That is, the multi-core optical ferrules currently generally used are 12MT ferrules with 12 cores in a row with a pitch of 250 μm and 16MT ferrules with 16 cores in a row with a pitch of 250 μm. Therefore, by making the multi-core optical ferrule with 24 cores in a row with a pitch P of 125 μm, it can have high connection compatibility with existing general-purpose multi-core optical ferrules. Specifically, when connecting 24 optical fibers, it is preferable that the pitch at the central portion is 250 μm and the pitch of the optical fiber insertion holes other than the central portion is 125 μm. In this way, by setting the pitch at the central portion of the optical fiber insertion holes to 250 μm and the pitch of the optical fiber insertion holes other than the central portion to 125 μm, the optical fibers with a double interval (12 optical fibers with a pitch of 250 μm) are compatible because their arrangement and communication method match those of the conventional 12-core optical fiber line, and the 12 optical fibers located therebetween can perform high-density communication as additional optical fibers. Therefore, it is possible to obtain a multi-core optical ferrule that is compatible with conventional optical connectors while enabling low-loss and high-density mounting communication.
[0023] (3) The multi-core optical ferrule according to the third invention is a multi-core optical ferrule according to the first aspect of the invention, in which 32 optical fiber insertion holes are provided and the pitch P is 125 μm.
[0024] This allows for high connection compatibility with general-purpose multi-core optical ferrules. In other words, the multi-core optical ferrules currently in general use are 12MT ferrules, which have 12 cores in a row with a pitch of 250 μm, and 16MT ferrules, which have 16 cores in a row with a pitch of 250 μm. Therefore, by creating a multi-core optical ferrule with 32 cores in a row with a pitch P of 125 μm, it is possible to achieve high connection compatibility with existing general-purpose multi-core optical ferrules.
[0025] Specifically, when connecting 32 optical fibers, it is preferable that the pitch of the central part be 250 μm and the pitch of the optical fiber insertion holes other than the central part be 125 μm. In this way, by setting the pitch of the optical fiber insertion holes in the central part to 250 μm and the pitch of the other parts to 125 μm, optical fibers with twice the spacing (16 optical fibers with a pitch of 250 μm) are compatible with conventional 16-core optical fiber lines in terms of arrangement and communication method, and the 16 optical fibers located in between become additional optical fibers, enabling high-density communication. Therefore, it is possible to obtain a multi-core optical ferrule that is compatible with conventional optical connectors while enabling low-loss and high-density mounting communication.
[0026] (4) The multi-core optical ferrule according to the fourth invention is, in the case of the multi-core optical ferrule according to any of the third inventions, the inner diameter of the large diameter portion may be 100 μm, and the distance of the small diameter portion may be 0.5 mm.
[0027] (5) The multi-core optical ferrule according to the fifth invention, as described above, is a multi-core optical ferrule according to the fourth invention in which the inner diameter of the small diameter portion has a tolerance of 10% or less on the + side and a tolerance of 5% or less on the - side, the pitch P of the optical fiber insertion hole has a tolerance of ±5% or less, and the bending angle of the optical fiber insertion hole may be 0.5° or less.
[0028] This allows for low-loss connections even with optical fibers having a cladding diameter of 80 μm. By setting the tolerance of the inner diameter of the small-diameter section to within 10% on the positive side and within 5% on the negative side (i.e., between +10% and -5%), a clearance of 0.5 μm can be secured within the narrow clearance provided in the small-diameter section, ensuring that the adhesive is reliably filled. This allows the optical fiber to be fixed with high positional accuracy at the connection end face.
[0029] In this case, the tolerance on the positive side of the inner diameter of the small diameter portion is preferably +10% or less, more preferably +8% or less, and even more preferably +5% or less. The tolerance on the negative side is preferably -5% or more, more preferably -2% or more, and even more preferably 0% or more.
[0030] The bending angle of the optical fiber insertion hole is defined as the angle formed by the perpendicular line to the connecting end face and the center line of the optical fiber insertion hole, viewed from a depth of 0.3 mm to 0.5 mm from the end face of the multi-core optical ferrule. By having a bending angle of 0.5° or less for the optical fiber insertion hole, reliable connection can be ensured when performing multimode optical communication. Furthermore, by having a bending angle of 0.3° or less for the optical fiber insertion hole, low-loss connection can be ensured even when performing single-mode optical communication.
[0031] (6) The multi-core optical ferrule according to the sixth invention, as described in one aspect, is a multi-core optical ferrule according to the fifth invention, in which the body may be an integrally formed body of a resin composition containing polyphenylene sulfide.
[0032] In this case, the main body is formed mainly from a resin composition containing polyphenylene sulfide, allowing for high dimensional accuracy. As a result, misalignment of the optical fiber can be suppressed, minimizing adverse effects on connection loss and other factors. Furthermore, even if the electronic components on the substrate are subjected to temperature changes due to operation, characteristics such as connection loss will not fluctuate. Therefore, even when optical wiring is mounted on the substrate, a ferrule for a multi-core optical connector with low connection loss can be obtained. In this specification, a ferrule for a multi-core optical connector may be simply referred to as a ferrule or MT ferrule.
[0033] (7) The multi-core optical ferrule according to the seventh invention, as described above, is a multi-core optical ferrule according to the sixth invention, in which the main body may be installed on a photoelectric conversion element or an optical transceiver provided on a substrate.
[0034] In this case, since a multi-core optical ferrule is installed on the photoelectric conversion element or optical transceiver on the circuit board, it can be directly connected to an optical fiber. This allows for optical mounting closer to electronic components (such as CPUs) on the circuit board. Furthermore, high-density optical lines can be implemented even in locations close to electronic components, enabling high-speed, high-capacity information processing. Furthermore, in this case, since the multi-core optical ferrule on the substrate side has connection compatibility, the ferrule on the optical fiber side may be an existing ferrule or the multi-core optical ferrule of the present invention. This makes it possible to create an optical mounting substrate with connection compatibility.
[0035] (8) A multi-core optical connector following other aspects is one in which optical fibers are connected from one aspect to a multi-core optical ferrule according to the seventh invention.
[0036] In this case, since it has connection compatibility with existing optical connectors, a multi-core optical connector can be obtained that can perform optical communication and high-density mounting communication. Furthermore, in optical connectors with small diameter and high density optical fibers, even a slight deviation in the relative positions of all optical fibers from the design can lead to communication problems. In particular, when multiple rows of optical fibers are used, the mold structure becomes complex, making it impossible to achieve precise positional accuracy for the optical fibers.
[0037] Therefore, in the multi-core optical connector according to the present invention, the maximum bending angle of the fiber hole can be achieved at 0.5 degrees or less. Furthermore, it is preferable that the maximum angle be 0.3 degrees or less. In addition, to achieve miniaturization and further suppress or prevent misalignment, it has multiple guide pin holes. By achieving miniaturization in this way, high-density, high-speed, high-capacity optical communication can be directly introduced to the substrate (or to the vicinity of the substrate), an optical mounting circuit that does not require electrical wiring can be realized, and compatibility with existing multi-core optical connectors can be maintained.
[0038] (9) A method for manufacturing a multi-core optical ferrule according to another aspect is a method for manufacturing a multi-core optical ferrule according to the seventh invention, wherein the body is molded by injecting a resin composition into a cavity formed between an upper mold and a lower mold, and the plurality of optical fiber insertion holes are formed by a plurality of mold pins sandwiched between the upper mold and the lower mold.
[0039] In this case, errors in the pitch and / or inclination of the multiple optical fiber insertion holes of the multi-core optical ferrule can be minimized. For example, if multiple optical fiber insertion holes are formed in two stages, the structure of the mold forming the multiple optical fiber insertion holes becomes complex, making it difficult to stably form the pitch and / or bending angle of the multiple optical fiber insertion holes. In other words, when multiple optical fiber insertion holes are arranged in a straight line (uniform arrangement), the multiple mold pins are firmly held between a pair of molds (upper mold and lower mold), and the main body is molded by injecting the resin composition into the cavity formed between the pair of molds. At the same time, the optical fiber insertion holes are formed in the places where the multiple mold pins were removed, thus minimizing errors in the bending angle of the fiber holes. [Brief explanation of the drawing]
[0040] [Figure 1] This is an example of a diagram showing the front view, top view, bottom view, right side view, and left side view of the ferrule of this embodiment. [Figure 2] This is a left side view of Figure 1. [Figure 3] This is a cross-sectional view taken along line A-A' in Figure 1(b). [Figure 4] This is a schematic diagram illustrating the ferrule of this embodiment. [Figure 5] This is a schematic diagram showing an example of an optical module mounted on a circuit board. [Figure 6] This is a schematic diagram illustrating an example of compatibility between the 24-core optical connector of this embodiment and existing 12-core optical connectors. [Figure 7] This is a schematic cross-sectional view illustrating the manufacturing method of the ferrule according to this embodiment. [Figure 8] This is a schematic diagram illustrating the manufacturing method of a conventional MT ferrule (2 rows). [Modes for carrying out the invention]
[0041] The embodiments of the present invention will be described below with reference to the drawings. Although multiple embodiments of the present invention are shown, each embodiment may be implemented independently or in combination of one or more embodiments. In the following description, identical parts are denoted by the same reference numeral. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.
[0042] [Embodiment] Figures 1(a), (b), (c), (d), and (e) are examples of diagrams showing the front view, top view, bottom view, right side view, and left side view of the ferrule 100 of this embodiment, respectively. Figure 2 is Figure 1(e), i.e., the left side view of this embodiment (enlarged view rotated 90° counterclockwise). Figure 3 is a cross-sectional view along line A-A' in Figure 1(b), and Figure 4 is a schematic diagram illustrating the ferrule 100 of this embodiment.
[0043] The multi-core optical ferrule 100 (hereinafter also simply referred to as ferrule 100) is a key component of the multi-core optical connector. It is provided on both the end face of one optical fiber and the end face of the other optical fiber to precisely adjust the position of the connecting end faces of each optical fiber and to apply contact force for optical connection. The ferrule 100 allows for the simultaneous connection of multiple optical fibers and can be formed by molding a resin composition containing polyphenylene sulfide (hereinafter referred to as PPS) in a mold. The ferrule 100 has an optical fiber insertion hole 103 for the optical fiber 11 and a guide pin hole 102 for inserting a guide pin, and is a single molded product (body) made of a resin composition containing polyphenylene sulfide.
[0044] (Ferrule 100) As shown in Figures 1 to 3, the ferrule 100 of this embodiment is provided with a fiber tape receiving port 101 for inserting an optical fiber tape, and a plurality of optical fiber insertion holes 103 for inserting and positioning an optical fiber 11 with its coating removed are provided communicating with the fiber tape receiving port 101. In addition, the ferrule 100 is provided with guide pin holes 102 for positioning and connecting a multi-core optical connector 12, which penetrate parallel to the optical fiber insertion holes 103.
[0045] The ferrule 100 of this embodiment has an opening 104 formed therein as an adhesive filling hole for filling with adhesive. The opening 104 is located approximately in the center of the upper surface of the ferrule 100 and is for filling with adhesive. The optical fiber tape is inserted into the fiber tape receiving port 101 from the rear side of the ferrule 100 after removing the coating from its tip. The exposed optical fibers 11 are then inserted into the optical fiber insertion holes 103 and fixed in place by the adhesive filling the opening 104. The connection end faces of the optical fibers 11 are fixed with the hardened adhesive after the optical fibers 11 are inserted into the ferrule 100 and polished together with the connection surface of the ferrule 100.
[0046] The optical fiber 11 is led out of the fiber tape receiving port 101 of the ferrule, protected by a boot made of an elastic material such as rubber or synthetic resin. The boot is fixed with adhesive to the boot insertion hole of the fiber tape receiving port 101 of the ferrule 100. In this embodiment, the ferrule 100 has an optical fiber insertion hole 103, a fiber tape receiving port 101, and an opening 104 that are in communication with each other. Below the filling portion where the adhesive is filled, a support portion 105 is provided, and guide grooves are formed in this support portion 105 for guiding and directing the optical fiber into the optical fiber insertion hole 103. The guide grooves in this embodiment are in communication with the rear end of the optical fiber insertion hole 103 and have a shape that is parallel to each other and has a semicircular cross-section.
[0047] As the optical fiber tape to be attached to the ferrule 100, an optical fiber tape core in which coated optical fiber strands are integrated with a common coating, or an optical fiber ribbon cord in which an additional protective coating is applied to the optical fiber tape core can be used.
[0048] (Guide pin hole 102) A guide pin (not shown) is pre-inserted and fixed into the guide pin hole 102 of one of the ferrules 100 that make up the multi-core optical connector. By inserting this guide pin into the guide pin hole 102 of the other ferrule 100 and bringing the connection surfaces of the multi-core optical connector 12 together, the optical fibers 11 are connected. In the ferrule 100 configured in this way, the axis of the optical fiber 11 is positioned by the guide pins, and the connection surfaces are brought together by a coupling clip or the like to perform an optical connection. Therefore, the ferrule 100 is provided with two guide pin holes 102 having a predetermined guide pitch Pg.
[0049] The guide pin diameter is preferably 0.7 mm or 0.55 mm, and the guide pitch is preferably 4.6 mm or 5.3 mm. Considering that 0.7mm guide pins are commonly used in existing MT ferrules, a 0.7mm guide pin diameter is preferable from the standpoint of connection compatibility. Furthermore, a 0.7mm guide pin offers higher reliability and alignment accuracy compared to a 0.55mm guide pin. In this embodiment, the guide pin hole 102 has an inner diameter of 0.699 mm, and a 0.700 mm guide pin is inserted into this guide pin hole 102. This allows for connection compatibility with conventional optical connectors and improves connection reliability.
[0050] Furthermore, the guide pitch Pg of the pair of guide pin holes 102 in this embodiment is 4.6 mm. The size of the guide pitch Pg is not particularly limited, but from the viewpoint of connection compatibility, it is preferable to use a guide pitch Pg that is commonly used in existing MT ferrules.
[0051] For example, single-mode or multi-mode optical fibers can be used as the optical fiber 11. Optical fibers 11 are standardized by the ITU-T (International Telecommunication Union - Telecommunication Standardization Sector) and the IEC (International Electrotechnical Commission), and in the case of those made of quartz glass, which is the most commonly used material, cladding diameters of 125 μm ± 1 μm and 80 μm ± 1 μm are specified. Currently, optical fibers 11 with a cladding diameter of 125 μm are the mainstream, but in the future, with the increasing demand for high-density packaging, the use of optical fibers 11 with a cladding diameter of 80 μm is expected. Therefore, in this embodiment, optical fibers 11 with a nominal cladding diameter of 80 μm are used. In addition, the number of cores in the optical fiber insertion hole 103 of the ferrule 100 can be, for example, 16 cores, 24 cores, 32 cores, or 60 cores.
[0052] The MT connector (JIS C5981) of this embodiment is cabled using ferrule 100 (JIS C5964-5) and can be connected using a positioning pin coupling method. Since the ferrule 100 of this embodiment conforms to existing pin coupling standards, it can be connected using conventional connecting components, thus providing connection compatibility with existing MT ferrules. Furthermore, it can be connected to optical transceivers and the like, enabling optical mounting on the substrate 14.
[0053] (Opening 104) Multiple optical fibers 11 are used as a tape core bundled together in a tape shape. The outer sheathing layer of this tape core is removed to a predetermined terminal length to expose the optical fibers 11, which are then inserted into the ferrule 100 and supported at a specified pitch for connection. The ferrule 100 may be a roughly rectangular parallelepiped with a stepped portion on its outside. One end face of the ferrule 100 is provided with a fiber tape receiving port 101 for receiving the tape core into the ferrule 100, and a support portion 105 for supporting the optical fibers 11 is provided.
[0054] The opening 104 is formed on the upper end surface of the ferrule 100 to connect the internal space with the outside, and as shown in Figure 2, it is vertically above the surface to which the adhesive is filled, and is a rectangular opening large enough to allow a view of the interior. The opening 104 is used to visually confirm the insertion of the optical fiber 11 into the support portion 105, and also as a filling port for pouring adhesive to fix the optical fiber 11 in place. The shape of the filling port (opening) 104 is arbitrary as long as it allows a clear view of the optical fiber insertion hole 103.
[0055] (Optical fiber insertion hole 103) The optical fiber insertion hole 103 is a hole that penetrates from the insertion surface to the connection surface of the support portion 105, and adjacent holes are formed parallel to each other. Furthermore, the axis of the optical fiber insertion hole 103 is positioned perpendicular to the connecting end face of the ferrule 100, thereby ensuring that the connecting end faces of the optical fibers come into precise contact on the same axis.
[0056] The angle of the optical fiber insertion hole 103 with respect to the connection end face is quantified as the bending angle. The bending angle of the optical fiber insertion hole 103 is the angle formed by the perpendicular line to the connection end face and the center line of the optical fiber insertion hole, viewed from a depth of 0.3 mm to 0.5 mm from the end face of the ferrule 100. The bending angle of the optical fiber insertion hole is preferably 0.5° or less. This ensures reliable connection when performing multimode optical communication. Furthermore, the bending angle of the optical fiber insertion hole is more preferably 0.3° or less. This allows for low-loss connection even when performing single-mode optical communication. The bending angle in this embodiment is a value measured as follows: The amount of misalignment of the fiber holes on the end face of the ferrule 100 is measured using a 2D / 3D automatic dimension measuring machine. To measure the amount of misalignment of the fiber holes, the intersection point of the line connecting the midpoints of the two guide holes and its perpendicular bisector is set as the coordinate (0,0), and then the position of each fiber hole is measured, and the difference between the measured value and the design value is calculated as the amount of misalignment. Furthermore, the amount of fiber hole displacement is calculated using the same method as described above, even at depths of 0.3 mm or more and 0.5 mm or less from the end face. In this way, the fiber hole bending angle is calculated from the difference between the displacement of the fiber hole at the end face and the displacement of the fiber hole at a predetermined depth.
[0057] Although the relationship between the connecting end face of the ferrule 100 and the optical fiber insertion hole 103 in this embodiment is as described above, in situations where two ferrules 100 are brought into contact to perform optical connection, the connecting end face of the ferrule 100 may be polished to an 8° angle to reduce the amount of return loss. In this case, the connection end faces will be inclined at an angle, but the two ferrules 100 will be brought into contact in a straight line by the guide pins, and the optical fibers 11 inside the ferrules 100 will be optically connected in a straight line.
[0058] The optical fiber insertion hole 103 is formed with a large-diameter section 106 and a small-diameter section 110 such that the diameter gradually decreases from the proximal end side through which the optical fiber 11 is inserted towards the tip side. In this embodiment, by setting the inner diameter of the small-diameter portion 110 to 81 μm, a clearance of radius 0.5 μm is created between it and the optical fiber with a cladding diameter of 80 μm. This clearance can be filled with adhesive, ensuring precise positional accuracy of the optical fiber connection end face while securely fixing it to the optical fiber. In other words, when attaching and fixing the optical fiber to the ferrule 100, adhesive is applied near the guide groove, and the optical fiber is inserted. As a result, the adhesive is pushed from the large-diameter section 106 to the small-diameter section 110 along with the inserted optical fiber, and the adhesive fills a clearance of radius 0.5 μm within the small-diameter section 110. Then, as the adhesive hardens, it shrinks, allowing the central axis of the small-diameter section 110 of the optical fiber insertion hole to precisely align with the central axis of the optical fiber. The inner diameter of the optical fiber insertion hole 103 can be appropriately changed according to the cladding diameter of the optical fiber to be inserted. For example, when using an optical fiber with a cladding diameter of 50 μm, the inner diameter of the small diameter section 110 may be set to 51 μm and the inner diameter of the large diameter section 106 to 80 μm.
[0059] (PCB mounting) Figure 5 shows an example of a schematic diagram of an optical module mounted on a substrate 14. The ferrule 100 is mounted inside the multi-core optical connector 12, which is fixed directly or nearby on the substrate 14 and connected to the photoelectric conversion element 13 via the optical fiber 11. There are no particular restrictions on what the ferrule 100 of this embodiment connects to; for example, it can be connected to an existing MT ferrule 200, and the optical fiber 11' extending from the MT ferrule 200 is routed to the side of the case 10.
[0060] When optically mounting an electronic circuit onto a substrate 14, an optical transceiver having a photoelectric conversion element 13 may be provided at the edge of the substrate 14 and connected to a multi-core optical connector 12 (Figure 5). An example of an optical transceiver is one in which a photodetector and a light-emitting element are housed together with a lens in a device holder as the photoelectric conversion element. In this device holder type optical transceiver, the leads (or their FPCs) of the photoelectric conversion element 13 are soldered to the substrate 14 and connected to a ferrule 100 attached to a receptacle fixed to the substrate 14. In this way, it becomes possible to mount optical wiring on a circuit board inside computers such as servers, and it can also be connected to optical fibers for long-distance communication between computers.
[0061] The connector for the ferrule 100 used as the multi-core optical connector 12 is not particularly limited, and for example, Lightray MPX connectors, MT-RJ connectors, and MPO connectors can be used. The ferrule 100 of this embodiment can be connected as a multi-core optical connector 12 using a general MPO housing (JIS C5982, IEC 61754-7 series) or the like. The housing may contain a compression spring to mechanically connect the optical fibers 11. This allows for easy attachment and detachment by push-pull operation.
[0062] The body of the ferrule 100 can be obtained, for example, by transfer molding using a thermosetting resin such as epoxy resin, injection molding using a thermoplastic resin such as polyphenylene sulfide resin (PPS), or liquid crystal polymer (LCP). The ferrule 100 of this embodiment is formed by molding a resin composition mainly composed of PPS. In addition to PPS, the resin composition may contain an inorganic filler. The inorganic filler may include silica particles or fibrous fillers.
[0063] (Connection compatibility) Figure 6 is a schematic diagram illustrating the connection compatibility between the ferrule 100 according to this embodiment and an existing 12-core MT ferrule 90. Currently, the most commonly used MT ferrules 90 are 12MT ferrules 90, which have a pitch of 250 μm and 12 cores in a single row. In recent years, 16MT ferrules, which have a pitch of 250 μm and 16 cores in a single row, have also been developed. Therefore, by creating a multi-core optical ferrule 100 with a pitch P of 125 μm and 24 or 32 cores in a single row, it is possible to achieve high connection compatibility with existing general-purpose MT ferrules 90. As shown in Figure 6, in the multi-core optical connector 12 according to this embodiment, the pitch Pm of the central optical fiber 11 is 250 μm, and the pitch P of the optical fibers other than the central part is 125 μm. In other words, the pitch Pm of the central part is designed to be twice the pitch P of the other parts. Furthermore, the guide pin diameter of the ferrule 100 in this embodiment is φ0.7 mm, and the guide pitch Pg of the pair of guide pin holes 102 is 4.6 mm, which is the same as that of the existing MT ferrule 90.
[0064] By arranging the optical fibers in this manner, the end faces of the odd-numbered optical fibers from the center are optically connected to the fiber end faces of the existing MT ferrules 90, allowing communication to proceed using conventional communication standards. The even-numbered optical fibers from the center are newly added optical fibers that are not present in the existing MT ferrules 90. Therefore, when two multi-core optical connectors 12 of this embodiment are connected, high-density optical communication including these newly added optical fibers becomes possible. In this case, the newly added optical fibers at even-numbered positions may communicate using the conventional communication standard or a different communication standard. For example, if the added optical fibers communicate using the conventional standard, the communication density can be doubled, and if they communicate using the new standard, such as high-frequency multiplexing, more than twice the amount of information can be transmitted. Therefore, the ferrule 100 of this embodiment enables high-speed, high-density optical communication, and is also compatible with and can communicate with existing MT ferrules 90.
[0065] An example of a compatible connection between the ferrule 100 according to this embodiment and an existing MT ferrule 90 will be described in detail using an enlarged view of Figure 6. The ferrule 100 of this embodiment and the existing MT ferrule 90 can be easily positioned using guide pins. In this case, the optical fiber 11b of the ferrule 100 of this embodiment is connected to the optical fiber 91a of the existing MT ferrule 90, the optical fiber 11d is connected to the optical fiber 91b, and the optical fiber 11f is connected to the optical fiber 91c. Furthermore, the optical fiber 11h of the ferrule 100 of this embodiment is connected to the optical fiber 91d of the existing MT ferrule 90, the optical fiber 11j is connected to the optical fiber 91e, the optical fiber 11m is connected to the optical fiber 91f, and the optical fiber 11n is connected to the optical fiber 91g. As a result, the existing 12-core MT ferrule 90 and the ferrule 100 of this embodiment can be optically connected and communicate with each other. Furthermore, since the optical fibers 11 of the ferrule 100 of this embodiment are arranged symmetrically, communication can be maintained even if the orientation of the ferrule 100 is changed. In this way, compatibility between the existing MT ferrule 90 and the ferrule 100 of this embodiment can be reliably maintained.
[0066] Furthermore, when the ferrule 100 of this embodiment is connected to the ferrule 100 of this embodiment, communication can be performed using the 24-core optical fiber 11, thereby enabling high-capacity communication. In particular, the optical fibers 11a, 11c, 11e, 11g, 11i, and 11k of the ferrule 100 in this embodiment are optical fibers 11 that are connected only to the ferrule 100 of this embodiment and are not connected to the existing MT ferrule 90. Therefore, it is possible to use the same communication method as the existing MT ferrule 90 or to use a new communication method. Therefore, the ferrule 100 of this embodiment enables high-speed, high-density optical communication, and is also compatible with existing MT ferrules 90, allowing them to communicate with each other.
[0067] Furthermore, in recent years, optical fibers with coating thicknesses of 200 μm or 180 μm are being developed for even higher density packaging, and in this case, 16-core optical fiber tapes with a 200 μm pitch are also being considered. In this case, the pitch Pm of the central part of the ferrule 100 is 200 μm, and the pitch P of the parts other than the central part is 100 μm. The inner diameter of the large diameter section may be 90 μm.
[0068] (Manufacturing method) Figure 7 is a schematic diagram showing the manufacturing method of the ferrule 100 in this embodiment. This explains the reason for arranging the optical fibers 11 in a straight line. As shown in Figure 7, an optical fiber insertion hole 103 is formed from a support portion 105 that supports the optical fiber 11, and the optical fiber insertion hole 103 is formed with a large diameter portion 106 and a small diameter portion 110 such that the diameter gradually decreases from the base end side through which the optical fiber is inserted to the tip end side. The guide groove of the support portion 105 is formed with a curvature of 100 μm in diameter, the large diameter portion 106 of the fiber insertion hole 103 is formed with a diameter of φ100 μm, and the small diameter portion 110 of the fiber insertion hole 103 is formed with a diameter of φ81 μm.
[0069] In this case, since the inner diameter of the large-diameter section 106 is less than 160 μm, only one optical fiber 11 with a cladding diameter of 80 μm can be inserted into each fiber insertion hole 103, thus reliably avoiding the inconvenience of two or more optical fibers 11 being inserted into a single fiber insertion hole 103. Moreover, since only the inner diameter of the large-diameter section 106 needs to be defined in this way, and no special configuration is required, the structure of the ferrule 100 does not become complicated.
[0070] Furthermore, the guide grooves of the support portion 105 are configured to communicate with the rear end of the large-diameter portion 106, be parallel to each other, and have a semicircular cross-section. These multiple guide grooves are for guiding the optical fiber 11 inserted from the rear side of the ferrule 100 into the fiber insertion hole 103. In this embodiment, the curvature of the guide groove is 100 μm, which is the same as the inner radius of the large-diameter portion 106. Therefore, the end face of the optical fiber placed in the guide groove is smoothly guided into the fiber insertion hole 103.
[0071] Here, Figure 8 shows an example of a manufacturing mold for an existing MT ferrule. In recent years, in order to increase communication capacity and communication speed, a method of increasing the density of optical fibers has been developed to create a 24-core MT ferrule by arranging 12 optical fibers in two rows. Figure 8 is an example of a mold for manufacturing an existing 24-core MT ferrule. As shown in Figure 8, the pin mold for forming the fiber insertion hole 103 is held and precisely positioned by a pin holder, as shown in Figure 8(b). However, when there are two rows of fiber insertion holes 103, as shown in Figure 8(b), it is necessary to stack three pin holders to hold the pin mold, which results in lower precision compared to the case of a single row. In the case of optical fibers with a cladding diameter of 125 μm, as in the past, there was no problem using a three-tiered pin holder as shown in Figure 8(b) to arrange the fiber insertion holes 103 in two rows. However, in the case of optical fibers with a cladding diameter of 80 μm, this precision issue cannot be ignored. In other words, when 12-core optical fibers with a cladding diameter of 80 μm are arranged in two rows, it becomes difficult to maintain high positional accuracy and angular precision of the optical fiber insertion holes 103 on the ferrule connection end face due to problems with the mold structure. As a result, when 24 optical fibers are connected by arranging 12 bundles of optical fibers in two rows as in the conventional method, the connection loss increases. Furthermore, this leads to a problem where the variation in product quality increases as the number of optical fibers increases.
[0072] In particular, if the bundle of 12 optical fibers is in one row, CH1 to CH12 are in the same row, so by reversing the connector on one side, it is possible to connect the same CH. However, if the bundle of 12 optical fibers is in two rows, CH1 and CH13 will be connected, resulting in unstable optical characteristics. In other words, when connecting optical fibers in a single row with identical misaligned end faces, the misalignment of the optical fiber end faces can be canceled out in the X-axis direction (optical fiber arrangement direction; transverse direction) at the time of connector connection because the misalignment occurs in the same direction at both connecting ferrules. On the other hand, in the Y-axis direction (vertical direction), the relative amount of misalignment increases because the misalignment occurs in the direction away from each other at both connecting ferrules. Thus, the positional accuracy in the Y-axis direction has a greater impact on connection loss than the positional accuracy in the X-axis direction. Therefore, when arranging a bundle of optical fibers in two rows, it is necessary to ensure connectivity between the upper and lower rows, which have different misalignment characteristics, and the problem arises that connection loss increases because the cancellation effect that occurs in the single-row case cannot be obtained.
[0073] Therefore, in this embodiment, as shown in Figure 7, since the multiple optical fiber insertion holes 103 are arranged in a straight line, the pin mold is held by only two pin holders, so that the pin mold for creating the optical fiber insertion holes 103 can be held precisely and reliably. As a result, the arrangement of the optical fiber insertion holes 103 and the fiber bending angle can be precisely controlled, and a high-precision ferrule 100 can be formed. In this embodiment, the inner diameter of the small diameter portion 110 of the ferrule 100 preferably has a tolerance of 5% or less on the positive side, and more preferably 3% or less. Furthermore, the tolerance of the negative side is preferably 0%. In addition, in this embodiment, the pitch P of the optical fiber insertion hole 103 of the ferrule 100 preferably has a tolerance of ±5% or less, and more preferably ±3% or less. Furthermore, in this embodiment, the bending angle of the optical fiber insertion hole 103 of the ferrule 100 preferably is 0.5° or less, and more preferably 0.3° or less. This makes it possible to create a ferrule 100 that is low-loss and high-density even in optical fibers with a cladding diameter of 80 μm, while maintaining compatibility with conventional optical connectors.
[0074] In the present invention, the optical fiber 11 corresponds to "optical fiber," the optical fiber insertion hole 103 corresponds to "optical fiber insertion hole," the guide pin hole 102 corresponds to "guide pin hole," the multi-core optical ferrule 100 corresponds to "multi-core optical ferrule," the large diameter portion 106 corresponds to "large diameter portion," the small diameter portion 110 corresponds to "small diameter portion," and the multi-core optical connector 12 corresponds to "multi-core optical connector."
[0075] While the above describes a preferred embodiment of the present invention, the present invention is not limited thereto. It will be understood that various other embodiments can be made without departing from the spirit and scope of the present invention. Furthermore, although the operation and effects of the configuration of the present invention are described in this embodiment, these operation and effects are examples and do not limit the present invention. [Explanation of Symbols]
[0076] 11 Optical Fiber 12-core optical connector 100 Multi-core optical ferrules 101 Fiber tape receiving port 102 Guide pin holes 103 Optical fiber insertion hole 104 Opening 105 Support part 106 Large diameter section 110 Small diameter section
Claims
1. The system comprises an electronic circuit board equipped with a photoelectric conversion element or an optical transceiver, an optical fiber connected to the photoelectric conversion element or the optical transceiver, and a multi-core optical ferrule connected to the optical fiber, The aforementioned multi-core optical ferrule is A multi-core optical fiber insertion hole into which optical fibers are inserted, It has two guide pin holes into which guide pins are inserted, The optical fiber insertion hole is arranged on a straight line connecting the two guide pin holes, When optical fibers are inserted into each of the aforementioned optical fiber insertion holes to form an optical connector, it can be connected to an optical connector with the same pitch P and the same number of optical fibers inserted, and can also be connected to an optical connector with twice the pitch Pm and half the number of optical fibers inserted. An optical circuit board in which optical fibers inserted into odd-numbered optical fiber insertion holes from one guide pin hole side of the multi-core optical ferrule and optical fibers inserted into even-numbered optical fiber insertion holes from one guide pin hole side are connected to a photoelectric conversion element or optical transceiver that transmits or receives optical signals of different communication standards.
2. The optical circuit mounting substrate according to claim 1, wherein the communication speed of the even-numbered optical fiber is faster than the communication speed of the odd-numbered optical fiber.
3. The aforementioned optical connector can connect optical fibers used for long-distance communication between computers and optical fibers used for optical wiring within computers. The odd-numbered optical fibers from one of the guide pin holes of the multi-core optical ferrule communicate using the communication method used for long-distance communication. The optical circuit mounting substrate according to claim 1 or 2, wherein the even-numbered optical fibers from the side of one of the guide pin holes of the multi-core optical ferrule communicate using the communication method used in the optical wiring.
4. The optical circuit mounting substrate according to any one of claims 1 to 3, wherein the optical fiber insertion holes are arranged symmetrically and allow for reverse connection.
5. The system comprises an electronic circuit board equipped with a photoelectric conversion element or an optical transceiver, an optical fiber connected to the photoelectric conversion element or the optical transceiver, and a multi-core optical ferrule connected to the optical fiber, The aforementioned multi-core optical ferrule is A multi-core optical fiber insertion hole into which optical fibers are inserted, It has two guide pin holes into which guide pins are inserted, The pitch Pm at the center of the row of multiple optical fiber insertion holes is twice the pitch P of the optical fiber insertion holes other than the center. An optical circuit board in which optical fibers inserted into odd-numbered optical fiber insertion holes from one guide pin hole side of the multi-core optical ferrule and optical fibers inserted into even-numbered optical fiber insertion holes from one guide pin hole side are connected to a photoelectric conversion element or optical transceiver that transmits or receives optical signals of different communication standards.
6. A computer comprising an optical circuit mounting substrate according to any one of claims 1 to 5.