Optical connectors and methods for connecting optical connectors

Abstract

To provide: an optical connector capable of preventing a spring force required for a connector from increasing when mounting optical fibers at high density to reduce a size; an optical connector connection structure; and an optical mounting circuit.SOLUTION: An optical connector includes: a first ferrule 110 including a first end surface 112 having an optical fiber insertion hole 114 for inserting an optical fiber 30 and a pair of guide pin insertion holes 116 for inserting a pair of guide pins 40; and a tabular lens holding member 200 bonded on the first end surface 112 of the first ferrule 110 through a refractive index matching adhesive layer. The lens holding member 200 includes a member body 210 and a GRIN lens 250 provided in the member body 210, and the GRIN lens 250 is optically combined with the optical fiber 30.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical connector, an optical connector connection structure, and an optical mounting circuit.

Background Art

[0002] A structure for connecting optical fibers generally uses two mated ferrule assemblies including ferrules to facilitate handling of the optical fibers and to accurately position them. Patent Document 1 (WO2019 / 244388) proposes an optical connector using a GRIN lens in order to increase optical coupling efficiency and reduce the influence on IL (transmission loss) due to foreign matter, misalignment, etc.

[0003] The optical connection component of Patent Document 1 includes a first end portion and a second end portion located on the opposite side of the first end portion. The first end portion has a first contact surface, a first recess, and a first bottom surface that contact the mating connector. The second end portion has a second contact surface, a second recess, and a second bottom surface that contact the MT ferrule. The first bottom surface and the second bottom surface face the optical fiber holding holes of the MT ferrule. This optical connection component further includes a guide hole through which a guide pin can be inserted. In the resin constituting the optical connection component, the transmittance is 80% or more and 100% or less with respect to light having a wavelength of 1210 nm or more and 1650 nm or less. The optical connector according to one embodiment includes the above-described optical connection component, a plurality of optical fibers, and an MT ferrule. GRIN lenses are fusion-connected to the tips of each of the plurality of optical fibers (paragraph 0021).

[0004] Patent Document 2 (Japanese Patent Application Laid-Open No. 2020-122816) discloses a ferrule and an optical connector that can easily mount a lens-attached optical fiber in which a GRIN lens is fusion-connected to the tip of an optical fiber while suppressing an increase in optical connection loss.

[0005] The ferrule and optical connector described in Patent Document 2 comprises a main body that holds a plurality of lensed optical fibers, each having a GRIN lens fused to its tip. The main body includes a lower member with a plurality of grooves extending along the X direction and aligned along the Y direction, and an upper member facing the plurality of grooves and separate from the lower member. The grooves include a first region for supporting the optical fibers and a second region located between the first region and the front end surface for supporting the GRIN lens. The lower member further includes a first recess provided between the first and second regions, the first recess accommodating the fused portion between the optical fiber and the GRIN lens.

[0006] Patent Document 3 (Japanese Patent Publication No. 2017-161831) discloses a spacer for an optical connector, an optical connector, and an optical connection structure that can improve durability against attachment and detachment of the optical connector and suppress a decrease in positioning accuracy.

[0007] The optical connector spacer described in Patent Document 3 comprises a plate-shaped main body including one end face facing the ferrule end face, another end face on the opposite side of the first end face, and an outer peripheral surface connecting the first and second end faces. The main body has an opening facing the optical fiber holding hole through which light passes from one end face to the other, a pair of recesses formed on at least one of the first and second end faces, and guide pin insertion holes formed within the pair of recesses through which a pair of guide pins penetrate from one end face to the other, with the guide pin insertion holes being positioned biased toward the opening side within the recesses. A lens array is provided on the ferrule end face. The lens array has a plurality of collimating lenses that collimate the light emitted from each optical fiber of the ferrule, and the collimating lenses are, for example, GRIN lenses (paragraph 0023).

[0008] Patent document 4 (Japanese Patent Publication No. 2016-95431) discloses an optical connector coupling system with improved reliability.

[0009] The optical connector coupling system described in Patent Document 4 comprises a first optical fiber, a first optical connector, a second optical fiber, a second optical connector, a spacer portion, and an adapter. The first optical connector comprises a first ferrule having a first optical interface portion and a first housing. The second optical connector comprises a second ferrule having a second optical interface portion and a second housing. The spacer portion is positioned on the first optical ferrule. With the first ferrule and the second ferrule positioned relative to each other, the first optical fiber is optically coupled to the second optical fiber via the first and second optical interface portions. The first optical interface portion has a plurality of GRIN (Gradient-Index) lenses arranged parallel to each other in the X-axis direction (paragraph 0042). [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] WO2019 / 244388 publication [Patent Document 2] Japanese Patent Publication No. 2020-122816 [Patent Document 3] Japanese Patent Publication No. 2017-161831 [Patent Document 4] Japanese Patent Publication No. 2016-95431 [Overview of the project] [Problems that the invention aims to solve]

[0011] In the connection structure of an optical connector, the optical fiber is fixed to the ferrule, and the end face of each optical fiber is positioned so as to be approximately flush with the end face of the ferrule, or so as to slightly protrude from the end face of the ferrule. The end faces of the optical fibers are generally polished to a predetermined finish.

[0012] The two ferrule assemblies are positioned and connected to each other via guide pins, and the connected optical connectors are secured together with clamp springs or the like. When the two ferrule assemblies are mated in this way, the optical fiber of one ferrule assembly comes into contact with the optical fiber of the other ferrule assembly with a predetermined pressing force.

[0013] The end faces of a pair of optical fibers are in physical contact with each other, causing optical transmission between the pair. In such optical connector connection structures, the efficiency of optical transmission between optical fibers is reduced by various factors. For example, irregularities or scratches on the end faces of the optical fibers, misalignment between the pair of optical fibers, and foreign matter such as dust and debris between the connected optical fibers. For example, when optical connectors are repeatedly connected and disconnected, foreign matter such as dust adhering to the surface of the guide pins may enter the guide pin insertion holes, making it difficult to insert and disconnect the guide pins smoothly. In this case, damage to the guide pin insertion holes may reduce the positioning accuracy of the optical connectors, potentially increasing coupling loss.

[0014] Because the optical path between optical fibers is small compared to the size of foreign objects such as dust or debris, such objects are prone to interfering with optical transmission. In this case, a beam connector that widens the width of the optical beam increases the relative size between beams with respect to foreign matter such as dust, thus reducing the effects of foreign matter and misalignment.

[0015] Therefore, it has been proposed to use a spherical lens to generate a magnified beam in order to reduce connection loss due to foreign matter, but the structure for aligning the spherical lens and the optical fiber becomes complex.

[0016] In the optical connection component described in Patent Document 1, a GRIN lens is fusion-spliced ​​to the end of each of the multiple optical fibers. In this case, it is not necessary to use a spherical lens, but productivity is reduced due to the fusion splicing process between the optical fiber and the GRIN lens. Also, connection loss may be large because it is difficult to achieve the required precision in the fusion splicing process. Furthermore, the outer diameter of the fusion portion between the optical fiber and the GRIN lens becomes larger than the outer diameters of the optical fiber and the GRIN lens.

[0017] Therefore, if the outer diameter of the fusion splice is larger than the optical fiber insertion hole in the ferrule, it becomes difficult to insert the fusion splice into the insertion hole. On the other hand, if the inner diameter of the insertion hole is larger than the fusion splice, the clearance between the insertion hole and the GRIN lens becomes larger, which makes misalignment of the GRIN lens more likely and increases optical connection loss. For this reason, a special structure is required for the ferrule that houses the optical fiber and the GRIN lens.

[0018] The ferrule described in Patent Document 2 also has the same drawbacks as Patent Document 1, as a GRIN lens is fused to the end face of the optical fiber, and a recess is formed in the ferrule to accommodate the fused portion.

[0019] In the optical connector described in Patent Document 3, the collimating lens is held in a through-hole provided in the lens holding member. Therefore, it is difficult to manufacture the lens holding member, and it is difficult to hold the lens in the very small hole of the lens holding member and to ensure accuracy. Furthermore, in Patent Document 3, the collimating lens and the ferrule are simply bonded together. However, the end face of the optical fiber is exposed to the ferrule, and when an optical signal is passed from this optical fiber to the collimating lens, there is a problem that light reflection or loss occurs at the interfaces between the optical fiber and the adhesive, and between the adhesive and the collimating lens.

[0020] In the optical connector coupling system described in Patent Document 4, similar to Patent Document 3, the GRIN lens provided in the first optical interface portion is configured such that the GRIN lens is provided in a through hole formed in the plate-shaped first optical interface portion. Therefore, it is difficult to process the first optical interface portion and to perform the operation and accuracy of inserting and arranging the lens in the lens holding member. In addition, in the optical connector coupling system described in Patent Document 4, since the lens array is fixed with a latch together with the spacer, problems such as the clearance between the guide pin and the guide pin hole and the displacement of each component during fitting using the latched spacer occur, resulting in variations in optical characteristics. During molding, if the holding hole is bent, the posture of the fiber optic with a lens held in the holding hole is likely to be inclined. When the posture of the fiber optic with a lens is inclined near the front end face, an angular displacement of the fiber optic with a lens occurs on the front end face, which may increase the optical connection loss between the optical connectors.

[0021] Furthermore, in the optical connectors described in the above patent documents, when densely mounting optical fibers, a large spring force is required (20 N or more in the case of 16 channels), resulting in a problem that it is difficult to achieve both high density and miniaturization. Therefore, an optical connector capable of optical connection with a lower pressing force is desired.

[0022] In recent years, an optical module has been developed in which an optical element is mounted on a substrate and the optical element and the optical fiber are optically coupled. As a result, a high-speed and high-density optical communication is directly introduced to (or near) the electronic substrate, and an optical mounting circuit without using an electrical communication wiring is being studied. When processing high-speed and large-capacity data, some electronic components on the substrate become hot during operation, so it may be necessary to submerge the entire electronic substrate in a refrigerant for cooling. However, conventional optical communication components are not designed on the premise of being immersed in liquid. Also, since the optical characteristics of an optical circuit are likely to change when it comes into contact with a liquid such as a refrigerant, there is a problem that when an optical connector is submerged in a refrigerant, it stops functioning or the loss becomes extremely large. In addition, the refrigerant may be circulated and may contain foreign matter. If the optical connector is immersed in this, the transmission loss may deteriorate due to the influence of the foreign matter.

[0023] The present invention has been made to solve the above drawbacks, and an object thereof is to provide an optical connector capable of reducing the influence on transmission loss due to foreign matter such as dust on the fiber end face during connection, misalignment, etc., an optical connector connection structure, and an optical mounting circuit. Another object of the present invention is to provide an optical connector, an optical connector connection structure, and an optical mounting circuit with high transmission efficiency even when used as a component of an immersion processor.

[0024] Another object of the present invention is to provide an optical connector, an optical connector connection structure, and an optical mounting circuit that can prevent an increase in the spring force required for the connector when densely mounting optical fibers and enable miniaturization. Still another object of the present invention is to provide an optical connector, an optical connector connection structure, and an optical mounting circuit that can use a conventional ferrule, have good processing accuracy, and have a lens holding member with a relatively simple structure.

Means for Solving the Problems

[0025] (1) An optical connector according to one aspect includes a first ferrule having a first end face in which an optical fiber insertion hole through which an optical fiber is inserted and a pair of guide pin insertion holes through which a pair of guide pins are inserted are formed, a plate-shaped lens holding member bonded to the first end face of the first ferrule via a refractive index matching adhesive layer, and a spacer provided on the side opposite to the first end face side of the lens holding member. The lens holding member has a member body and a GRIN lens provided on the member body. The spacer has a light guiding portion that allows the light transmitted through the GRIN lens to pass through. The GRIN lens is optically coupled to the optical fiber.

[0026] This eliminates the need to fuse a GRIN lens to the end of the optical fiber, allowing the use of conventional ferrules. By using a GRIN lens to enlarge the beam diameter and transmit signals through space, it becomes possible to reduce the impact of transmission loss caused by foreign matter such as dust and misalignment at the fiber end face during connection. In particular, even when the optical connector is immersed in a refrigerant, the impact of foreign matter contained in the refrigerant can be reduced. Furthermore, while high-density mounting of optical fibers requires a large spring force (for example, 20N or more for 16 channels), spatial transmission allows for holding with a spring force of around 3N. In other words, unlike the PC (Physical Contact) method, non-contact optical connection structures allow for simultaneous optical connection of numerous optical fibers without requiring a large force for optical connection.

[0027] In particular, GRIN lenses have a problem where the length of the lens directly affects the focal length, and thermal fusion of the surface of the GRIN lens affects the length of the lens, resulting in the inability to obtain accurately parallel light rays and affecting connection loss. Furthermore, since GRIN lenses are formed by creating a spatial distribution of refractive index by giving a concentration distribution to the glass components, fusion of the lens affects the spatial distribution of concentration, resulting in the inability to obtain stable optical properties. The optical connector of the present invention adheres a plate-shaped lens holding member to the first end face of the first ferrule using a refractive index matching adhesive, so that optical properties can be reliably maintained without performing fusion at the connection surface between the optical fiber and the GRIN lens.

[0028] Furthermore, the optical connector may be an MT connector or MPO connector equipped with an MT ferrule. By using an MT ferrule as the first ferrule, a compact and high-density connection connector can be realized using a commonly available MT ferrule.

[0029] (2) The optical connector according to the second invention is an optical connector according to one aspect of the invention, wherein the refractive index of the light guide portion of the spacer may be 1.2 or more and 1.6 or less.

[0030] This minimizes light reflection at the interface between the GRIN lens of the lens holding member and the light guide portion of the spacer. In this case, the light guide portion of the spacer may be made of a resin or glass having a predetermined refractive index, or it may be filled with a liquid having a predetermined refractive index. The spacer body may also be made of a transparent resin material, and a refractive index matching agent may be applied between the spacer body and the GRIN lens of the lens holding member.

[0031] (3) The optical connector according to the third invention is a single-face or second-face optical connector, and the light guide portion may have an opening filled with a fluorine-based refrigerant.

[0032] When the optical connector is immersed in a fluorine-based refrigerant, the fluorine-based refrigerant fills the opening formed in the spacer. As a result, light emitted from the GRIN lens of the lens holding member can pass through the light guide portion of the spacer without reflection. Furthermore, since the refrigerant can be used as the filling material for the light guide portion, the optical connector can be suitably used in systems in which the server is immersed in liquid.

[0033] In immersion servers, the entire electronic circuit board of the optically mounted circuit is submerged in a refrigerant tank containing a liquid refrigerant, thereby cooling the processor and other components. The liquid refrigerant filling the inside of the immersion server has a higher specific heat than air, and the flow of the refrigerant reduces the temperature gradient, allowing for efficient heat removal. Furthermore, if a fluorine-based refrigerant with a low boiling point of 50 degrees Celsius (122 degrees Fahrenheit) is used, it will boil quickly due to the heat generated by the processor and other components. The heat of vaporization (heat absorbed from the surroundings when a liquid turns into a gas) at this time can also be used for server cooling. When the optical connector is immersed in a fluorine-based refrigerant, the fluorine-based refrigerant fills the opening formed in the spacer. As a result, light emitted from the GRIN lens of the lens holding member can pass through the light guide portion of the spacer without reflection. Furthermore, since the refrigerant can be used as the filling material for the light guide portion, the optical connector can be suitably used in systems in which the server is immersed in liquid.

[0034] The refractive index of the refrigerant in the immersion processor is preferably between 1.2 and 1.6. By immersing the optical connector in the refrigerant tank containing the refrigerant, the refrigerant fills the opening of the spacer, cooling the optical mounting circuit and simultaneously enabling optical connection of each component without hindrance. When using Fluorinert® as the refrigerant, the refractive index is between 1.25 and 1.30. Furthermore, conventional spherical lenses, such as plastic lenses designed for use in air, would either cease to function or undergo a significant change in focal length when used in an immersion processor, making it impossible to construct an expanded beam. On the other hand, by using a GRIN lens as in the present invention, an expanded beam can be realized in an immersion state without being affected by the refrigerant.

[0035] In other inventions, the optical connector may be immersed in a coolant for cooling electronic components.

[0036] In recent years, there has been active development of optical modules in which optical elements are mounted on a substrate and optically coupled with optical fibers. This has led to the consideration of optically mounted circuits that do not require electrical wiring, by directly introducing high-speed, high-density optical communication to (or near) the electronic substrate. On the other hand, some electronic components on a circuit board become hot during operation, so the entire circuit board is sometimes cooled by submerging it in a liquid coolant. However, optical circuits are prone to changes in optical properties when exposed to liquids such as coolants, so submerging optical connectors in a coolant often results in them becoming non-functional or experiencing extremely high losses. Unlike conventional optical systems that use spherical lenses, the optical connector according to the other invention can achieve a stable, widened beam even in an immersion state, unaffected by the coolant, even when used in an immersion processor, resulting in an optical connector with high transmission efficiency.

[0037] (4) The optical connector according to the fourth invention is an optical connector according to any of the third inventions, wherein the spacer has a frame and the frame may have two or more flow channels.

[0038] The spacer may have a channel in its frame for guiding the refrigerant to the light guide. This channel allows the refrigerant to be smoothly guided to the light guide, efficiently filling the light guide with the refrigerant, and thus stabilizing the optical properties in a short time. The spacer may have one flow path, but it is preferable to have two or more. Having two or more flow paths allows air present in the opening of the frame to be efficiently released to the outside when immersed in the refrigerant, thus enabling the light guide section to be filled with the refrigerant more efficiently.

[0039] (5) The optical connector according to the fifth invention is an optical connector according to any of the fourth inventions, wherein a resin reservoir recess or protrusion for refractive index matching adhesive may be formed on the first end face of the first ferrule and / or on the member body of the lens holding member.

[0040] This allows for a uniform thickness of the adhesive layer, thereby stabilizing the optical properties. Furthermore, it prevents excess adhesive from entering guide pin insertion holes, thus suppressing problems such as guide pins being unable to be properly inserted.

[0041] (6) The optical connector connection structure according to the sixth invention comprises: a first ferrule having a first end face formed with an optical fiber insertion hole through which an optical fiber is inserted and a pair of guide pin insertion holes through which a pair of guide pins are inserted; a plate-shaped lens holding member bonded to the first end face of the first ferrule via a refractive index matching adhesive layer; a second optical connector disposed opposite to the first end face of the first ferrule; and a spacer disposed between the lens holding member and the second optical connector, having a light guiding portion that can allow light to pass between the lens holding member and the second optical connector. The lens holding member comprises a plate-shaped member body and a GRIN lens provided on the member body, the GRIN lens being aligned with the end face of the optical fiber inserted through the optical fiber insertion hole, the member body being constructed by joining a lower plate member and an upper plate member, and a holding hole for holding the GRIN lens being formed on the joint surface between the lower plate member and the upper plate member.

[0042] This eliminates the need to fuse a GRIN lens to the end of the optical fiber, allowing the use of conventional ferrules. The main body of the component is constructed by joining a lower plate member and an upper plate member, and a retaining hole for holding the GRIN lens is formed in the joint surface between the lower plate member and the upper plate member. Therefore, a lens retaining member having a retaining hole can be manufactured easily and with high precision. Furthermore, since the GRIN lens can be placed in the holding hole before joining the lower and upper plate members, and then the lower and upper plate members can be joined together, the GRIN lens can be held in the holding hole with high precision.

[0043] By using a GRIN lens to enlarge the beam diameter and transmit signals through space, it becomes possible to reduce the impact on IL (transmission loss) caused by foreign matter such as dust and misalignment at the fiber end face during connection. In particular, even when the optical connector is immersed in a liquid such as a refrigerant, the impact of foreign matter contained in the refrigerant can be reduced. Furthermore, when implementing high-density mounting of 16 channels or more, using MPO requires a spring force of 20N or more, whereas spatial transmission allows for holding with a spring force of around 3N. In other words, unlike the PC (Physical Contact) method, the non-contact optical connector connection structure 1 allows for simultaneous optical connection of numerous optical fibers without requiring significant force for optical connection. Furthermore, since a plate-shaped lens holding member is bonded to the first end face of the first ferrule using a refractive index matching adhesive, the optical properties can be reliably maintained at the connection surface between the optical fiber and the GRIN lens.

[0044] The optical connector may be an MT connector or MPO connector equipped with an MT ferrule, or it may be a dedicated connection connector. By using an MT ferrule as the first ferrule, a compact and high-density connection connector can be realized using a commonly available MT ferrule.

[0045] (7) The optical connector connection structure according to the seventh invention is the optical connector connection structure according to the sixth invention, wherein the second optical connector includes a second ferrule having a second end face, and the second end face of the second ferrule may have an optical fiber insertion hole through which an optical fiber is inserted and a pair of guide pin insertion holes through which a pair of guide pins are inserted.

[0046] This reduces the impact of foreign matter such as dust and misalignment on the fiber end face during connection on transmission loss, and also prevents an increase in the spring force required for the connector when optical fibers are densely mounted, enabling a miniaturized optical connector connection structure.

[0047] (8) The optical mounting circuit according to the eighth invention comprises a refrigerant tank containing a refrigerant and an electronic component, wherein the electronic component is immersed in the refrigerant of the refrigerant tank, and the optical connector connected to the electronic component comprises a first ferrule having a first end face formed with an optical fiber insertion hole through which an optical fiber is inserted and a pair of guide pin insertion holes through which a pair of guide pins are inserted, and a plate-shaped lens holding member bonded to the first end face of the first ferrule via a refractive index matching adhesive layer, wherein the lens holding member comprises a member body and a GRIN lens provided on the member body, and the GRIN lens is aligned with the end face of the optical fiber inserted through the optical fiber insertion hole.

[0048] This reduces the impact of foreign matter such as dust and misalignment on the fiber end face during connection on transmission loss, and also prevents an increase in the spring force required for the connector when optical fibers are densely mounted, enabling a miniaturized optical connector connection structure.

[0049] (9) The optical mounting circuit according to the ninth invention is the optical mounting circuit according to the eighth invention, wherein the lens holding member has a first surface on the first end face side of the first ferrule and a second surface on the opposite side of the first surface, a spacer is disposed on the second surface side of the lens holding member, the spacer has an opening that allows light transmitted through the GRIN lens to pass through, and the opening is filled with a medium.

[0050] This reduces the impact of foreign matter such as dust and misalignment on the fiber end face during connection on transmission loss, and also prevents an increase in the spring force required for the connector when optical fibers are densely mounted, enabling a miniaturized optical connector connection structure.

[0051] The refractive index of the refrigerant in the immersion processor is preferably between 1.2 and 1.6. Therefore, by immersing the optical connector in the water tank containing the refrigerant, the refrigerant fills the opening of the spacer, cooling the optical connector connection structure and simultaneously enabling optical connection of each component without hindrance. When using Fluorinert® as the refrigerant, the preferred refractive index is between 1.25 and 1.30. Furthermore, conventional spherical lenses, such as plastic lenses designed for use in air, would either cease to function or undergo a significant change in focal length when used in an immersion processor, making it impossible to construct an expanded beam. On the other hand, by using a GRIN lens as in the present invention, an expanded beam can be realized in an immersion state without being affected by the refrigerant. [Brief explanation of the drawing]

[0052] [Figure 1] This is an exploded perspective view of the optical connector connection structure of Embodiment 1. [Figure 2] Figure 1 is an exploded plan view of the optical connector connection structure. [Figure 3] Figure 1 is an exploded front view of the optical connector connection structure. [Figure 4] Figure 1 is a plan view of the optical connector connection structure. [Figure 5] Figure 1 shows the front view, top view, bottom view, left side view, and right side view of the ferrule used in the optical connector connection structure. [Figure 6] This is a schematic diagram illustrating the lens holding member of Embodiment 1. [Figure 7] This is a schematic perspective view illustrating the lens holding member of Embodiment 1. [Figure 8] This is a reference cross-sectional diagram (cross-sectional diagram along line A-A' in Figure 4) for explaining the operation of the optical connector and the optical beam. [Figure 9] This is a schematic perspective view illustrating a lens holding member of another embodiment. [Figure 10] This is a schematic perspective view illustrating the lens holding member of yet another embodiment. [Figure 11]This is a schematic perspective view illustrating the spacer of Embodiment 1. [Figure 12] This is a schematic perspective view illustrating other forms of spacers. [Figure 13] This is a schematic perspective view illustrating other forms of spacers. [Figure 14] This is a schematic perspective view illustrating other forms of spacers. [Figure 15] This is a schematic perspective view illustrating other forms of spacers. [Figure 16] This is a schematic perspective view illustrating other forms of spacers. [Figure 17] This is a schematic perspective view illustrating other forms of spacers. [Figure 18] This is a schematic perspective view illustrating other forms of spacers. [Modes for carrying out the invention]

[0053] 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.

[0054] [Embodiment 1] (Optical connector connection structure 1) Figure 1 is an exploded perspective view showing one embodiment of the optical connector connection structure 1. Figure 2 is an exploded plan view showing the optical connector connection structure 1, and Figure 3 is an exploded front view of the optical connector connection structure 1. As shown in Figures 1 to 3 and Figure 6, the optical connector connection structure 1 of this embodiment comprises a first ferrule 110, a plate-shaped lens holding member 200 bonded to the first end face 112 of the first ferrule 110 via a refractive index matching adhesive layer (not shown), a second optical connector 20 disposed opposite the first end face 112 of the first ferrule 110, and a spacer 300 disposed between the lens holding member 200 and the second optical connector 20, having a light guide portion 310 that allows light to pass between the lens holding member 200 and the second optical connector 20.

[0055] Furthermore, as shown in Figures 1 to 5, the first optical connector 10 of this embodiment includes a first ferrule 110 having a first end face 112 through which an optical fiber insertion hole 114 through which an optical fiber 30 is inserted and a pair of guide pin insertion holes 116 through which a pair of guide pins 40 are inserted, and a plate-shaped lens holding member 200 bonded to the first end face 112 of the first ferrule 110 via a refractive index matching adhesive layer.

[0056] The second optical connector 20 may have a second ferrule 120 and a plate-shaped lens retaining member 200 bonded to the second end face 122 of the second ferrule 120 via a refractive index matching adhesive layer. In such a case, the optical connector connection structure 1 comprises a first ferrule 110 and a second ferrule 120 connected to each other, a first lens retaining member 200, a second lens retaining member 200' positioned between the first and second ferrules 110 and 120, and a spacer 300.

[0057] (Refractive index matching adhesive layer) The refractive index matching adhesive used in the refractive index matching adhesive layer preferably has a refractive index of 1.4 to 1.5 after curing, and more preferably 1.45 to 1.48. This minimizes the connection loss between the optical fiber 30 and the GRIN lens 250, and also minimizes the generation of reflected light. As the refractive index matching adhesive for the refractive index matching adhesive layer, an acrylic or epoxy-based optical adhesive can be used. The refractive index matching adhesive may be a thermosetting adhesive or a UV-curing adhesive. If there are opaque components, a thermosetting adhesive is preferable, and if there are heat-sensitive components, a UV-curing adhesive is preferable. This minimizes the connection loss between the optical fiber 30 and the GRIN lens 250, and also minimizes the generation of reflected light.

[0058] (ferrule) The first and second ferrules 110 and 120 each have a substantially rectangular parallelepiped appearance and are molded from, for example, a resin. The first and second ferrules 110 and 120 may be formed from a moldable resin such as polyphenylene sulfide or liquid crystal polymer (LCP), and may also contain additives such as silica (SiO2) to enhance the strength and stability of the resin. They may also be formed from an inorganic material such as ceramics. The first and second ferrules 110 and 120 each have a flat first end face 112 and a second end face 122 provided on one end in the connection direction, and a rear end face 113 and 123 provided on the other end. The first and second ferrules 110 and 120 also have a pair of side surfaces extending along the connection direction, as well as a bottom surface and a top surface. The first end face 112 of the first ferrule 110 and the second end face 122 of the second ferrule 120 are positioned facing each other.

[0059] The first end face 112 and the second end face 122 have a pair of guide pin insertion holes (guide holes) 116 formed in a direction that intersects the cross-section along the optical axis of the optical fiber 30. A pair of guide pins 40, 40 are inserted into the pair of guide pin insertion holes 116. That is, the relative positions of the first ferrule 110 and the second ferrule 120 are determined by the pair of guide pins 40, 40.

[0060] The first end face 112 has multiple optical fiber insertion holes 114 into which optical fibers 30 are inserted. The rear end faces 113 of the first and second ferrules 110 and 120 have introduction holes 117 for receiving a ribbon fiber consisting of multiple optical fibers 30 (Figure 5(d)). Multiple optical fiber insertion holes 114 are formed to penetrate from the first end face 112 to the introduction hole 117. An optical fiber 30 is inserted into and held in each of these optical fiber insertion holes 114.

[0061] The optical fibers 30 each extend along the connection direction and are arranged in a single row horizontally intersecting the connection direction. The number of optical fiber insertion holes 114 can be determined according to the purpose. There may be one (in which case it will be a single-core ferrule) or multiple (in which case it will be a multi-core ferrule). In this embodiment, examples of multi-core MT ferrules such as 12-core and 16-core ferrules in which the optical fibers 30 are arranged in a single row are described. The optical fiber 30 in this embodiment has a bare optical fiber and a resin coating covering the bare optical fiber, and the bare optical fiber is exposed by removing the resin coating from the middle to the tip in the connection direction. A bare optical fiber is held in the optical fiber insertion hole 114. The tip of each bare optical fiber is exposed at the first end face 112, and is, for example, flush with the first end face 112 or slightly protruding. In this invention, a bare optical fiber is also simply referred to as an optical fiber 30.

[0062] In this embodiment, the inner diameter of the optical fiber insertion hole 114 is set to 125.5 μm or more and 127.5 μm or less, and a multimode fiber with an outer diameter of 125 μm is used. In this case, the core diameter of the optical fiber 30 is 50 μm. In this embodiment, the case of transmitting a 1300 nm optical signal using a multimode optical fiber with a cladding diameter of 125 μm is described. However, the optical fiber 30 may have a cladding diameter of 80 μm or the like, and may be multimode or singlemode. The wavelength of the optical signal can also be appropriately selected according to the purpose. For example, a multimode fiber (small-diameter cladding fiber) with a core diameter of 50 μm and a cladding diameter of 80 μm may be used, or a single-mode fiber with a core diameter of 10 μm and a cladding diameter of 80 μm or 125 μm can be used. In this case, the inner diameter of the optical fiber insertion hole 114, the lens design of the GRIN lens 250, the physical properties of the refrigerant, etc., can be appropriately selected according to the selected optical fiber or optical signal.

[0063] (Lens holding member 200) Plate-shaped lens holding members 200 and 200' are provided on the first end face 112 of the first ferrule 110 and the second end face 122 of the second ferrule 120, respectively. The lens holding member 200 has a plurality of GRIN lenses 250 that diffuse and collimate the light emitted from the optical fiber 30 of the first ferrule 110. The GRIN lenses 250 are held in holding holes 220 formed in the lens holding member 200. The lens holding member 200' disposed on the second ferrule 120 side also has a plurality of GRIN lenses 250 that focus the light that has passed through the light guide portion 310 of the spacer 300. The GRIN lenses 250 are held in holding holes 220 formed in the lens holding member 200'. The array pitch of each GRIN lens 250 is set to be equal to the array pitch of the optical fibers 30 held by the first and second ferrules 110 and 120. Each GRIN lens 250 is arranged in correspondence with the optical fibers 30, optically connecting the GRIN lenses 250 and the optical fibers 30.

[0064] Each GRIN lens 250 is cylindrical in shape, and its central axis is positioned to coincide with the central axis of the optical fiber 30. In this embodiment, the optical fiber 30 is a multimode fiber with an outer diameter of 125 μm and a core diameter of 50 μm. In this case, the outer diameter of each GRIN lens 250 is preferably 130 μm to 300 μm, more preferably 150 μm to 250 μm, and even more preferably 180 μm to 220 μm. As a result, the 50 μm diameter multimode beam diameter is expanded to a diameter of 100 μm to 120 μm and transmitted collimated, thereby reducing transmission loss due to foreign matter at the connection point. Furthermore, the beam carrying the communication signal is collimated by the GRIN lens 250, allowing the signal to be transmitted non-contact between the first and second ferrules 110 and 120. Therefore, even when connecting high-density optical fibers, there is no need to apply strong force with physical contact, allowing for a smaller optical connector. Furthermore, unlike conventional optical systems using spherical lenses, even when the optical connector is used in an immersion processor, it is unaffected by the refrigerant and can achieve a stable, widened beam even in an immersion state, resulting in an optical connector with high transmission efficiency.

[0065] As shown in Figures 6 and 7, the lens holding member 200 is formed in a plate shape including a first surface 202 facing the first end surface 112, a second surface 204 on the opposite side of the first surface 202, and an outer peripheral surface 206 connecting the first surface 202 and the second surface 204.

[0066] Furthermore, guide holes 224 are formed at both ends of the lens holding member 200, through which guide pins 40 that penetrate from the first surface 202 to the second surface 204 are inserted. The spacing between the pair of guide holes 224, 224 formed in the lens holding member 200 is set to be equal to the spacing between the pair of guide pin insertion holes 116, 116 formed on the end face of the first ferrule 110.

[0067] Details of the lens holding member 200 in this embodiment are as follows. The lens holding member 200 has a horizontally elongated plate-shaped member body 210 and a GRIN lens 250 provided on the member body 210. The main body 210 is constructed by joining a lower plate member 212, which is long in the lateral (horizontal) direction, and an upper plate member 214, which is also long in the lateral (horizontal) direction, vertically. The lower plate member 212 and the upper plate member 214 may be joined together using an adhesive. A retaining hole 220 for holding the GRIN lens 250 is formed between the upper surface (joint surface) of the lower plate member 212 and the lower surface (joint surface) of the upper plate member 214. Specifically, a recess 216 is formed on the joint surface of the lower plate member 212, and the joint surface of the upper plate member 214 is joined to the joint surface of the lower plate member 212, thereby forming a retaining hole 220 between the recess 216 and the joint surface of the upper plate member 214.

[0068] The cross-sectional shape of the recess 216 may be U-shaped, V-shaped, semicircular, or the like. In this embodiment, as shown in Figure 6, the recess 216 is formed in an inverted triangular cross-section. Since the joining surface (bottom surface) of the upper plate member 214 is formed as a flat surface, when the joining surface (bottom surface) of the upper plate member 214 is joined to the joining surface (top surface) of the lower plate member 212, an inverted triangular retaining hole 220 is formed between them. In the embodiments shown in Figures 6 and 7, a plurality of inverted triangular retaining holes 220 are formed in a continuous manner (like a saw blade) along the longitudinal direction of the member body 210.

[0069] The lens holding member 200 can be formed from inorganic materials such as quartz, glass, or ceramics, or from resin, which can be precisely machined. By machining the member body 210 by cutting or other methods, the inverted triangular-shaped recess 216 and the inverted triangular-shaped holding hole 220 can be accurately formed. The lens holding member 200 may also be formed from a transparent resin. Due to the high machining accuracy, the GRIN lens 250 can be positioned in the holding hole 220 as designed and aligned (optically coupled) with the end face of the optical fiber 30.

[0070] To hold the GRIN lens 250 in the holding hole 220 of the lens holding member 200, the GRIN lens 250 is placed in the recess 216 of the lower plate member 212, and then the joining surface of the upper plate member 214 is joined to the joining surface of the lower plate member 212. The GRIN lens 250 can be bonded and fixed to the holding hole 220 using adhesive. For example, after placing and holding the GRIN lens 250 in the recess 216, the GRIN lens 250 may be fixed to the recess 216 by filling the recess 216 with adhesive, or the GRIN lens 250 may be held in the holding hole 220 and then the holding hole 220 may be filled with adhesive to bond it.

[0071] Furthermore, the cross-sectional shape of the lower recesses 218 formed at both ends of the lower plate member 212 may be semicircular, U-shaped, or V-shaped. Similarly, the cross-sectional shape of the upper recesses 222 formed at both ends of the upper plate member 214 may be semicircular, U-shaped, or V-shaped. In this embodiment, the lower recess 218 formed in the lower plate member 212 has an inverted triangular cross-section, and the upper recess 222 has a triangular cross-section. Therefore, when the joining surface (upper surface) of the lower plate member 212 is joined to the joining surface (upper surface) of the upper plate member 214, a diamond-shaped guide hole (guide pin insertion hole) 224 is formed between them.

[0072] By machining the lens holding member 200, a recess with an inverted triangular cross-section and a holding hole 220 with an inverted triangular cross-section can be accurately formed.

[0073] When bonding the joint surface of the lower plate member 212 to the joint surface of the upper plate member 214 with an adhesive, suitable adhesives include thermosetting epoxy resin-based and cyanoacrylic-based adhesives. Specifically, adhesives such as acrylic, epoxy, vinyl, silicone, rubber, urethane, methacrylic, nylon, bisphenol, diol, polyimide, fluorinated epoxy, and fluorinated acrylic adhesives can be used. Silicone and acrylic adhesives are particularly preferred.

[0074] To prevent the guide pin 40 from adhering to the guide pin insertion hole 116 due to the adhesive used to join the lower plate member 212 and the upper plate member 214, and the adhesive used to fix the GRIN lens 250 to the lens holding member 200, an adhesive reservoir may be provided on the lens holding member 200. For example, an adhesive reservoir may be provided between the guide pin insertion hole 116 and the holding hole 220.

[0075] In the lens holding member 200 configured in this way, the GRIN lens 250 held by the lens holding member 200 is aligned with the end face of the optical fiber 30 inserted through the optical fiber insertion hole 114 and optically coupled. Therefore, the light emitted from the optical fiber 30 will pass through the GRIN lens 250. There may be more than one GRIN lens 250. Multiple GRIN lenses 250 may be provided at regular intervals along the longitudinal direction (lateral direction) of the lens holding member 200.

[0076] In one embodiment of the optical connector, the main body of the component is constructed by joining a lower plate member and an upper plate member, and a retaining hole for holding a GRIN lens may be formed in the joining surface between the lower plate member and the upper plate member.

[0077] The main body of the component is constructed by joining a lower plate member and an upper plate member, and a retaining hole for holding the GRIN lens is formed in the joint surface between the lower plate member and the upper plate member. Therefore, a lens retaining member having a retaining hole can be manufactured easily and with high precision. Furthermore, since the GRIN lens can be placed in the holding hole before joining the lower and upper plate members, and then the lower and upper plate members can be joined together, the GRIN lens can be held in the holding hole with high precision.

[0078] In one embodiment of the optical connector, a recess may be formed on the joining surface of the lower plate member, and a retaining hole may be formed between the recess and the joining surface of the upper plate member by joining the joining surface of the upper plate member to the joining surface of the lower plate member.

[0079] To hold the GRIN lens in the holding hole of the lens holder, the GRIN lens is placed in the recess formed in the joint surface of the lower plate member, and then the joint surface of the upper plate member is joined to the joint surface of the lower plate member. Therefore, the manufacturing of the lens holder member becomes relatively simple, the processing accuracy of the holding hole is improved, and the GRIN lens can be held in the lens holder member with high precision.

[0080] In one embodiment of the optical connector, lower recesses for guide holes are formed at both ends of the joining surface of the lower plate member, and upper recesses for guide holes are formed at both ends of the joining surface of the upper plate member. By joining the joining surface of the lower plate member and the joining surface of the upper plate member, guide holes may be formed between the lower recesses and the upper recesses at both ends of the lens holding member.

[0081] This makes it possible to manufacture lens holding members with guide holes (guide pin insertion holes) with high precision and relatively easy. Furthermore, the lens holding member can be formed from inorganic materials such as quartz, glass, and ceramics, or resin, which can be precisely machined. By processing the main body of the member, a recess with an inverted triangular cross-section and a holding hole with an inverted triangular cross-section can be accurately formed.

[0082] In one embodiment of the optical connector, the lens holding member may have a lower recess with an inverted triangular cross-section, an upper recess with a triangular cross-section, and a guide hole with a rhombic cross-section.

[0083] The lens holder can be formed from inorganic materials such as quartz, glass, and ceramics, or from resin, which are capable of precision machining. By machining the main body of the holder, a recess with an inverted triangular cross-section and a guide hole for inserting a guide pin with an inverted triangular cross-section can be precisely formed.

[0084] In one embodiment of the optical connector, the joint surface of the lower plate member and the joint surface of the upper plate member may be bonded together with an adhesive. The joint surface of the lower plate member and the joint surface of the upper plate member can be bonded together with an adhesive, allowing for easy manufacture of the lens holding member.

[0085] (Lens holding member 200a in another embodiment) In other embodiments, the lens holding member 200a has a circular (cylindrical) holding hole 220 for holding the GRIN lens 250, and is integrally formed with the lower plate member 212 and the upper plate member 214 without being separated. Figure 9 shows a schematic perspective view illustrating the lens holding member 200a of other embodiments. In other embodiments, the inner diameter of the holding hole 220 of the lens holding member 200a is preferably 1 μm to 3 μm larger than the diameter of the GRIN lens 250. In the case of fixing the GRIN lens 250 to the lens holding member 200a of another embodiment, adhesive is applied to the GRIN lens 250 before inserting it into the holding hole 220. When the GRIN lens 250 is inserted into the holding hole 220, a misalignment may occur between the cross-sectional center position of the GRIN lens 250 and the cross-sectional center position of the holding hole 220. However, the curing shrinkage stress of the adhesive works to hold the GRIN lens 250 at the cross-sectional center of the holding hole 220 during curing, thus enabling a lens holding member 200a with high assembly accuracy.

[0086] (GRIN Lens 250) The GRIN lens 250 is configured such that its refractive index gradually changes from the center outward (having a refractive index distribution). The GRIN lens 250, held by the lens holding member 200, is configured to magnify the light beam emitted from the optical fiber 30. The GRIN lens 250 is also configured to collimate the divergent light emitted from the optical fiber 30 and emit parallel light in the direction of emission. Since the GRIN lens 250 has flat optical surfaces on both sides, it facilitates the attachment of the GRIN lens 250 to the holding hole 220 of the lens holding member 200. GRIN lenses can be used with a base rod whose refractive index distribution has been formed by an "ion exchange" process, in which the rod is immersed in a high-temperature molten salt. After ion exchange, the rod is cut to the appropriate length for the application and both ends are polished. The length of the GRIN lens 250 is preferably 0.5 mm to 1.5 mm, and more preferably 0.8 mm to 1.2 mm. In this case, the size of the lens holding member 200 and the holding hole 220 can be reduced. The GRIN lens 250 of the lens holding member 200, which is disposed on the second ferrule 120 side, is configured to collect the light beam, which is parallel light that has passed through the light guide portion of the spacer and entered the GRIN lens 250, and to focus it onto the optical fiber 30.

[0087] (Spacer 300) As shown in Figures 1 to 3 and Figure 11, the spacer 300 is sandwiched between the first end face 112 of the first ferrule 110 and the second end face 122 of the second ferrule 120, between the pair of lens holding members 200, 200'. That is, the spacer 300 can control the distance between the first end face 112 of the first ferrule 110 and the second end face 122 of the second ferrule 120 to be constant. The distance between the pair of ferrule end faces is controlled by the distance between the pair of lens holding members 200 controlled by the spacer 300. The spacer 300 may be bonded to at least one of the lens holding members 200, or it may be joined by welding (laser welding, etc.). When the spacer 300 is bonded to the lens holding member 200, an MPO connector is preferred for bonding.

[0088] As shown in Figure 11, the spacer 300 comprises a spacer body 305 including one end face 301, another end face 302 on the opposite side of the one end face 301, and an outer peripheral surface 303 connecting the one end face 301 and the other end face 302. The one end face 301 of the spacer 300 faces the first end face 112 of the first ferrule 110, and the other end face 302 of the spacer 300 faces the second end face 122 of the second ferrule 120. The spacer body 305 may have an opening 311 as a light guide portion 310 that allows light to pass through between one end face 301 and the other end face 302. In this embodiment, as shown in Figure 11, the spacer 300 is provided with a pair of guide holes 320, 320 for inserting guide pins and an opening 311 for allowing light to pass through. The optical path formed between the pair of lens holding members 200, 200' passes through this opening 311 (light guide portion 310). The inside of this opening 311 may be filled with a gas or liquid of a predetermined refractive index. If the optical connector is immersed in liquid, a predetermined coolant may be filled inside. In addition, the inside of the opening 311 may be provided with a transparent resin or glass of a predetermined refractive index. If the spacer body 305 has an opening 311, the spacer body 305 is formed in a frame shape. If the spacer 300 does not have an opening, the spacer body 305 may be formed of a plate-like member (for example, a sheet) that is transparent to the wavelength of light transmitted through it.

[0089] Furthermore, a pair of guide holes 320, 320 are formed at both ends of the spacer 300, through which a guide pin 40 is inserted, penetrating from one end face 301 to the other end face 302. The spacing between the pair of guide holes 320, 320 is set to be equal to the spacing between the pair of guide pin insertion holes 116, 116 and the pair of guide holes 224, 224.

[0090] In this embodiment, one end face 301 of the spacer 300 is bonded to the lens holding member 200 positioned on the first end face 112 of the first ferrule 110. The other end face 302 of the spacer 300 then contacts the lens holding member 200 positioned on the second end face 122 of the second ferrule 120 when connecting to the second ferrule 120. Here, the optical connector (first optical connector) 10 is formed by the first ferrule 110, the lens holding member 200 bonded to the first ferrule 110, and the spacer 300.

[0091] The positions of the first optical connector 10, the lens holding member 200, and the spacer 300 are fixed by inserting a pair of guide pins 40 through a pair of guide pin insertion holes 116 and a pair of guide holes 224 in the first ferrule 110, and a pair of guide holes 320 in the spacer 300.

[0092] In this embodiment, a ferrule and optical connector for optically coupling two multimode optical fibers 30 have been described, but the present invention can also be applied to a ferrule and optical connector for optically coupling two single-mode optical fibers 30.

[0093] (Function of optical connector) Next, the optical coupling between the optical fiber 30 fixed to the first ferrule 110 of the first optical connector 10 and the optical fiber 30 fixed to the second optical connector 20 will be described below. The light beam propagates through the optical fiber 30 fixed to the first ferrule 110 and enters the GRIN lens 250 of the lens holding member 200. The GRIN lens 250 then amplifies the light beam, and it is emitted towards the light guide portion 310 (aperture 311) of the spacer 300. As shown in Figure 8, the GRIN lens 250 collimates the divergent light from the optical fiber 30, converting it into a substantially parallel light beam.

[0094] The light beam, magnified by the GRIN lens 250, propagates through the light guide section 310 and, upon entering the GRIN lens 250 of the second optical connector 20, is focused by the GRIN lens 250 onto the end face of the optical fiber 30 fixed to the second ferrule 120, and propagates through the optical fiber 30. In this way, the optical fiber 30 fixed to the first ferrule 110 and the optical fiber 30 fixed to the second ferrule 120 are optically coupled via the lens holding member 200 and the spacer 300.

[0095] According to the optical connector connection structure 1 of this embodiment, the optical beam is expanded between the first optical connector 10 and the second optical connector 20. Therefore, with the optical connector connection structure 1 of this embodiment, light is transmitted and received in the expanded optical beam configuration, which can suppress connection losses caused by misalignment or the presence of foreign matter between the first optical connector 10 and the second optical connector 20 in a plane (XY plane) perpendicular to the optical coupling direction (Z axis direction). Consequently, connection losses in optical properties due to misalignment, foreign matter on the end face of the optical fiber during connection, etc., can be reduced.

[0096] The second optical connector 20 includes a second ferrule 120 having a second end face 122, the second end face 122 of the second ferrule 120, which may have an optical fiber insertion hole through which an optical fiber 30 is inserted and a pair of guide pin insertion holes through which a pair of guide pins 40 are inserted. As a result, the pair of guide pins 40 precisely align the pair of guide pin insertion holes 116 in the first ferrule 110, the pair of guide holes 224 in the lens holding member 200, the pair of guide holes 320 in the spacer 300, the pair of guide holes 224 in the lens holding member 200', and the optical fiber insertion hole in the second ferrule 120. This optically connects the optical fiber 30 of the first optical connector 10 and the optical fiber 30 of the second optical connector 20, forming the optical connector connection structure 1.

[0097] The optical mounting circuit according to this embodiment comprises a refrigerant tank containing a refrigerant and an electronic component, wherein the electronic component is immersed in the refrigerant of the refrigerant tank. In this case, the refractive index of the refrigerant is preferably between 1.2 and 1.6. By having the refractive index within this range, the effect of light reflection occurring at the interface between the GRIN lens 250 and the refrigerant can be minimized, and connection loss can also be minimized. When using Fluorinert® as a refrigerant, the refractive index is preferably 1.25 to 1.30, and more preferably 1.26 to 1.28. This allows it to be used in a variety of cooling applications as it is a chemically stable insulator. Furthermore, since various boiling points can be selected, it can be used in single-phase applications where it is kept in liquid form, or in two-phase applications where it is boiled and cooled by the latent heat of vaporization. Optically mounted circuits refer to electronic devices that require ultra-high performance and stable operation, such as supercomputers and data centers, and that generate a large amount of heat themselves, but are not limited to these. Electronic components include processors, memory, and servers, and these electronic components have optical connectors.

[0098] The optical connector used in the optical mounting circuit can be the same optical connector used in the above embodiment. In other words, the optical connector comprises a first ferrule 110 having a first end face 112 through which an optical fiber insertion hole 114 through which an optical fiber is inserted and a pair of guide pin insertion holes 116 through which a pair of guide pins 40 are inserted, and a lens holding member 200 bonded to the first end face 112 of the first ferrule 110 via a refractive index matching adhesive layer, wherein the lens holding member 200 has a member body 210 and a GRIN lens 250 provided on the member body 210, and the GRIN lens 250 is aligned to correspond to the end face of the optical fiber inserted through the optical fiber insertion hole 114. Furthermore, the lens holding member 200 has a first surface 202 on the side of the first end face 112 of the first ferrule 110 and a second surface 204 on the opposite side of the first surface 202. A spacer 300 is disposed on the side of the second surface 204 of the lens holding member 200, and the spacer 300 has an opening 311 (light guide portion 310) that allows light transmitted through the GRIN lens 250 to pass through, and the opening 311 (light guide portion 310) is filled with a coolant. According to the optical mounting circuit of this embodiment, it is an immersion cooling system that uses a fluorocarbon-based coolant.

[0099] (Assembly Instructions) Next, the process of placing the lens holding member 200 on the first end face 112 of the first ferrule 110 will be described. With each of the pair of jig guide pins inserted into the corresponding guide pin insertion hole 116 of the first ferrule 110 and the guide hole 224 of the lens retaining member 200, the lens retaining member 200 is temporarily placed slightly away from the first end face 112. Then, refractive index matching adhesive is supplied between the rear surface of the lens retaining member 200 and the first end face 112, and the lens retaining member 200 and the first end face 112 are brought into close contact, thereby fixing the lens retaining member 200 to the first ferrule 110 via the refractive index matching adhesive. Finally, each of the pair of jig guide pins is removed from the corresponding guide pin insertion hole 116 and guide hole 224.

[0100] In this way, each GRIN lens 250 is positioned relative to the end face of the corresponding optical fiber 30, so that each GRIN lens 250 is optically coupled to the corresponding optical fiber 30. Furthermore, each guide pin insertion hole 116 is positioned relative to the corresponding guide hole 224, so that each guide pin insertion hole 116 communicates with the corresponding guide hole 224.

[0101] (Lens holding member 200b of another embodiment) Figure 10 shows a lens holding member 200b in which a pair of resin reservoir recesses 280 are formed on the first end face 112 side of the first ferrule 110 of the lens holding member 200b. The resin reservoir recesses 280 are formed as grooves running vertically between the holding hole 220 and the guide hole 224. By filling the space between the pair of resin reservoir recesses 280 with refractive index matching adhesive, the thickness of the adhesive layer can be easily made uniform, thereby stabilizing the optical properties. In addition, this prevents excess adhesive from entering the guide hole 224, etc., thereby suppressing problems such as the guide pin 40 not being able to be inserted correctly. The structure of the resin reservoir may include not only a recess (resin reservoir recess 280) but also a protrusion. By making the resin reservoir a recess, the amount of adhesive dripped can be reduced, and the strength around the guide pin insertion hole 116 can be ensured. In this embodiment, the resin reservoir recess 280 or protrusion of the lens holding member 200b may be provided on a lens holding member 200b with a circular (cylindrical) holding hole 220 as shown in Figure 9. Furthermore, the resin reservoir protrusion or recess may be provided on the lens holding member 200 side or on the spacer 300 side.

[0102] (Spacer 300a in another embodiment) Figure 12 shows an example of a spacer 300a with a flow path 350 formed therein. The spacer 300a in this embodiment has a frame having an opening 311, and a flow path 350 is formed in the frame, communicating the opening 311 with the outside of the frame. This allows an external gas or liquid (such as a refrigerant) to be introduced into the opening 311 through the flow path 350. The flow path 350 may penetrate from one end face 301 to the other end face 302 of the spacer body 305 as shown in Figure 12, or a concave flow path 350 that does not penetrate the end face of the spacer body 305 may be formed as shown in Figure 13.

[0103] (Spacer 300b in another embodiment) Figure 13 is a schematic perspective view showing an example of a spacer 300b with two or more flow channels 350. In this embodiment, two flow channels 351 and 352 are provided on one end face 301 and the other end face 302 of the spacer body 305 (on opposite sides of the frame), and these flow channels 351 and 352 can be formed on the top and bottom of the frame. By providing multiple flow channels 351 and 352, when the optical connector including the spacer 300a is immersed in a refrigerant, the air present in the opening 311 of the frame can be released to the outside through the flow channels 351 and easily replaced with the refrigerant.

[0104] (Spacer 300c in other embodiments) Figure 14 is a schematic perspective view showing an example of a spacer 300c in which a through-hole 331 serving as a light guide is provided in the spacer body 305. The through-hole 331 is a through-hole in which an opening 311 for guiding the optical signal and a guide hole 320 for inserting a guide pin 40 are integrated. A flow path 350 may also be provided in this spacer 300c.

[0105] (Spacer 300d in other embodiments) Figure 15 is a schematic perspective view showing an example of a spacer 300d in which a through-hole 332 serving as a light guide is provided in the spacer body 305. In this embodiment, the through-hole 332 is formed to penetrate the plate-shaped spacer body 305 in a slit-like manner. Therefore, the through-hole 332 in this embodiment is an integrated entity comprising an opening 311 for guiding optical signals, a guide hole 320 for inserting a guide pin 40, and a flow path 350 for introducing liquid or the like. The inner part of the through-hole 332 is located at a position corresponding to the guide hole.

[0106] (Spacer 300e in other embodiments) Figure 16 is a schematic perspective view showing an example of a spacer 300e in which a spacer body 305 is provided with multiple openings 312. Each of the multiple openings 312 is provided so that its central axis coincides with that of the GRIN lens 250. The size of the openings 312 is set to be the same as or larger than the diameter of the optical surface of the GRIN lens 250. As a result, since multiple openings 312 are provided for each GRIN lens 250, the intrusion of stray light from adjacent GRIN lenses 250 can be reliably prevented.

[0107] (Spacer 300f in other embodiments) Figure 17 shows an example of another embodiment of the spacer 300f, in which the spacer 300f is entirely made of a transparent resin or glass having a predetermined refractive index. In this case, since the spacer body 305 of the spacer 300f functions as a light guide 310, the spacer 300f is provided with a guide hole 320, but it is not necessary to provide a through hole (such as an opening 311). In this case, the spacer 300f is in close contact with or bonded to the lens holding member 200, and is configured so that liquid does not enter the optical path even when immersed in a refrigerant or the like. This makes it possible to reduce connection loss without being affected by liquid. In the example in Figure 17, the spacer 300f is shown to be a resin or glass body having a predetermined thickness, but it is not limited to this, and the spacer 300f may be a resin film or the like.

[0108] (Spacer 300g in other embodiments) Figure 18 shows an example where the guide hole 320 of the spacer 300f (Figure 17) is a guide hole 321 formed as a slit that penetrates the outer circumferential surface 303 of the spacer body 305. In this case, the spacer 300g can be easily machined.

[0109] In the present invention, the optical connector connection structure 1 corresponds to the "optical connector connection structure," the optical fiber 30 corresponds to the "optical fiber," the first ferrule 110 corresponds to the "first ferrule," the second ferrule 120 corresponds to the "second ferrule," the optical fiber insertion hole 114 corresponds to the "optical fiber insertion hole," the guide pin insertion hole 116 corresponds to the "guide pin insertion hole," the first end face 112 corresponds to the "first end face," the lens holding member 200 corresponds to the "lens holding member," the member body 210 corresponds to the "member body," the GRIN lens 250 corresponds to the "GRIN lens," the second optical connector 20 corresponds to the "second optical connector," and the spacer 300 corresponds to the "spacer."

[0110] 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]

[0111] 1. Optical connector connection structure 10. First optical connector (optical connector) 20. Second optical connector 30 optical fibers 40 guide pins 110 First ferrule 114 Optical fiber insertion hole 116 Guide pin insertion holes 120 Second ferrule 200 Lens holding member 210 Main body component 212 Lower plate member 214 Upper plate member 216 recess 220 Retaining hole 224 Guide hole (guide pin insertion hole) 250 GRIN lens 300 Spacer 310 Light guide section 311 Opening 320 Guide hole (guide pin insertion hole) 350 channels

Claims

1. An optical connector connected to an electronic component immersed in the refrigerant of a refrigerant tank, A first ferrule having an optical fiber insertion hole through which an optical fiber is inserted, and a pair of guide pin insertion holes, A lens holding member provided on the connecting end face side of the first ferrule and having a pair of guide pin insertion holes, The lens holding member comprises a spacer provided on the side opposite to the first ferrule, having a pair of guide pin insertion holes, The spacer has an opening through which the light from the optical fiber passes and which is filled with the refrigerant, and a flow path through which the refrigerant and / or the air in the opening passes. The lens holding member holds a lens that expands the beam diameter of the optical fiber, An optical connector that is detachably positioned via guide pins.

2. An optical connector connected to an electronic component immersed in the refrigerant of a refrigerant tank, A first ferrule having an optical fiber insertion hole through which an optical fiber is inserted, A spacer having an opening is provided on the connecting end face side of the first ferrule, The system includes a lens that expands the beam diameter of light passing through the aperture, The opening of the spacer allows light from the optical fiber to pass through and is filled with the refrigerant. The spacer further has a channel for passing the refrigerant and / or air within the opening, wherein the optical connector.

3. A method for connecting an optical connector to an electronic component immersed in the refrigerant of a refrigerant tank, A first ferrule having an optical fiber insertion hole through which an optical fiber is inserted, and a pair of guide pin insertion holes, A lens holding member provided on the connecting end face side of the first ferrule, having a pair of guide pin insertion holes, A spacer provided on the side of the lens holding member opposite to the first ferrule, having a pair of guide pin insertion holes, an opening through which the light of the optical fiber passes, and a flow path for the coolant and / or air within the opening, The process of connecting the second ferrule provided on the electronic component side in this order, The process includes filling the opening of the spacer with the refrigerant through the flow path, The lens holding member holds a lens that expands the beam diameter of the optical fiber, A method for connecting an optical connector, wherein the optical connector is detachably positioned via guide pins.

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