Self-repairing optical waveguide, its manufacturing method and its reconnection method

Abstract

A self-repairing optical waveguide made of a composite polymer of a photopolymer and a self-repairing polymer, a method for manufacturing the same, and a method for reconnecting the self-repairing optical waveguide are provided. [Solution] The above-mentioned problem is solved by a self-healing optical waveguide formed between opposing optical waveguides and a composite polymer, wherein the composite polymer comprises a copolymer or mixed polymer of a photopolymer and a self-healing polymer, and the self-healing polymer is a polymer of monomers having a host group and a guest group and bonding through host-guest interaction. In this case, it is preferable that the photopolymer is a polymer of one or more photopolymerizable monomers, and the self-healing polymer is a polymer of a composition having a host group-containing polymerizable monomer and a guest group-containing polymerizable monomer.

Description

[Technical Field]

[0001] The present invention relates to a self-repairing optical waveguide, a method for manufacturing the same, and a reconnection method for the same. More specifically, the present invention relates to a self-repairing optical waveguide made of a composite polymer of an optical polymer and a self-repairing polymer, a method for manufacturing the same, and a reconnection method for a self-repairing optical waveguide that can reconnect a disconnected self-repairing optical waveguide simply by butting together the disconnected portions of the self-repairing optical waveguide. [Background technology]

[0002] There is a need for higher speeds and larger capacities in communications between electronic devices installed in automobiles and other vehicles, and optical communications is becoming mainstream to meet this need. The development of high-speed optical communications systems for in-vehicle use is particularly anticipated for the realization of autonomous driving in the future. For in-vehicle optical communications systems, plastic optical fibers with a core diameter of 1 mm are being considered for gigabit speeds, while multimode optical fibers (glass and plastic) with a core diameter of approximately 50 μm are being considered for speeds of over 10 gigabits. Furthermore, methods for connecting such optical fibers to light-receiving and light-emitting elements, as well as to connect optical fibers to relay connectors, are also being considered.

[0003] Vehicles such as automobiles generate vibrations when traveling on roads, and conventional optical fiber aligning connector connections are prone to optical axis misalignment due to vibration. When an optical axis misalignment occurs, it is difficult to reconnect the optical fibers by aligning the optical axes, and this is extremely difficult, especially in the case of small core diameters, in terms of transmission loss and cost. Therefore, the use of self-written optical waveguides, which can automatically align and connect optical fibers, is being considered as a method of connecting optical fibers that is less likely to cause optical axis misalignment. Such self-written optical waveguides are advantageous in that they can significantly reduce costs.

[0004] Self-written optical waveguides are formed by inserting an optical fiber into a photopolymerizable resin, irradiating the resin with laser light, and growing a core from the tip of the optical fiber without misalignment with the optical fiber core. Because the resin hardens after polymerization, self-written optical waveguides formed in this way can sometimes be damaged by vibration.

[0005] To address these problems, Patent Document 1 proposes a method for manufacturing a self-written optical waveguide that is less susceptible to misalignment and the resulting breakage and peeling even under vibration conditions, and that can ensure a satisfactory connection. A and a photopolymerizable polymer gel material A that polymerizes when irradiated with light at a wavelength λ B (≠λ A ) and a photopolymerizable polymer gel material B that polymerizes when irradiated with light of wavelength λ. One end of an optical fiber is immersed in the mixture, and light of wavelength λ is emitted from the other end of the optical fiber. A The photopolymerizable polymer gel material A is polymerized in the axial direction of the optical axis of the optical fiber by irradiating the laser beam of wavelength λ B This is a method of irradiating light to polymerize photopolymerizable polymer gel material B. This technology makes it possible to form flexible self-forming optical waveguides, which are less likely to become misaligned and the resulting breakage and peeling even under vibration conditions, and it has been reported that a satisfactory connection can be ensured. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-36382 [Patent Document 2] Japanese Patent Application Publication No. 2020-143220 Summary of the Invention [Problem to be solved by the invention]

[0007] In automotive optical communication systems, it is necessary to disconnect and reconnect connected optical components during periodic inspections, etc. Therefore, in the case of optical fibers, optical fibers connected via an optical adapter also need to be disconnected from the optical adapter and then reconnected. However, as mentioned above, the optical fiber connection method using an optical adapter has the drawback that the optical axis is easily misaligned due to vibration, and also when the optical fiber is disconnected from the optical adapter and then reconnected.

[0008] Furthermore, although the self-forming optical waveguides in which optical fibers are connected using the above-mentioned conventional photopolymerizable polymer gel material have the advantage of being flexible, separating (cutting) the optical fibers after polymerization and then reconnecting them requires many steps, making it difficult. To reconnect the optical fibers, for example, the optical fibers must be separated and inspected periodically, the cut surfaces of the cut optical fibers must be brought together, a photopolymerizable resin monomer must be injected between the cut surfaces, laser light must be irradiated from the cut surfaces of the optical fibers, and photopolymerization must be performed again to form and connect the self-forming optical waveguide. This requires many steps and is not practical.

[0009] The present invention has been made to solve the above-mentioned problems, and its object is to provide a self-healing optical waveguide made of a composite polymer of a photopolymer and a self-healing polymer, a method for manufacturing the same, and a method for reconnecting a disconnected self-healing optical waveguide that can be reconnected simply by butting together the disconnected parts of the self-healing optical waveguide. [Means for solving the problem]

[0010] (1) The self-healing optical waveguide of the present invention is a self-healing optical waveguide formed between opposing optical waveguides using a composite polymer, characterized in that the composite polymer has a copolymer or mixed polymer of an optical polymer and a self-healing polymer, and the self-healing polymer is a polymer of monomers having a host group and a guest group and bonding through host-guest interaction.

[0011] The self-repairing optical waveguide of this invention is a self-repairing optical waveguide formed by connecting optical waveguides (e.g., optical fibers) facing each other (optical fibers, planar optical waveguides, etc., hereinafter referred to as "optical fibers" for ease of understanding) with a composite polymer, and therefore has lower transmission loss than the current common method of connecting optical fibers with connectors connected using an optical adapter, and does not cause optical axis misalignment due to vibrations, etc. Furthermore, even if the connection between the optical fibers is cut due to reasons such as periodic inspection of the optical communication system, the self-repairing optical waveguide of this invention can self-repair by simply butting the cut parts together afterwards. Furthermore, the composite polymer comprises a copolymer or mixed polymer of a photopolymer and a self-healing polymer, and the self-healing polymer is a polymer of monomers that have host and guest groups and bond through host-guest interaction. Therefore, when the optical waveguide is first formed, the photopolymer-forming composition and the self-healing polymer composition can be copolymerized or polymerized to form a mixed polymer, and when reconnecting after disconnection, the self-healing polymer that has host and guest groups and bonds through host-guest interaction exhibits reversible self-healing properties, enabling reconnection. This allows the optical waveguide to be re-formed and reconnected by self-healing simply by butting the disconnected parts together, without the need to apply a photopolymer-forming composition to the disconnected part or irradiate it with light for polymerization, as in the conventional method.

[0012] (2) In the self-healing optical waveguide of the present invention, the photopolymer is a polymer of one or more types of photopolymerizable monomers, and the self-healing polymer is a polymer of a composition having a host group-containing polymerizable monomer and a guest group-containing polymerizable monomer.

[0013] (3) In the self-repairing optical waveguide according to the present invention, the monomer ratio of the photopolymerizable monomer constituting the photopolymer to the sum of the host group-containing polymerizable monomer and the guest group-containing polymerizable monomer constituting the self-repairing polymer is preferably within a range of 9.9:0.1 to 0.1:9.9. According to this invention, the monomer ratio can be adjusted as desired within the above range depending on the hardness, flexibility, degree of self-repairing property, etc. of the self-repairing optical waveguide.

[0014] (4) In the self-repairing optical waveguide of the present invention, the photopolymer is obtained by photopolymerizing a photopolymer-forming composition containing one or more photopolymerizable monomers, a photopolymerization initiator, and a light absorber.

[0015] (5) In the self-repairing optical waveguide according to the present invention, the two or more photopolymerizable monomers are blended in a ratio that corresponds to the photopolymerizability, flexibility, refractive index of the core and clad, and cross-sectional area of ​​the optical waveguide. According to this invention, the photopolymerizability, flexibility, refractive index of the core and clad, and cross-sectional area of ​​the self-repairing optical waveguide can be adjusted by polymerizing a photopolymer-forming composition containing an arbitrary blend of two or more photopolymerizable monomers.

[0016] (6) The method for manufacturing a self-repairing optical waveguide according to the present invention is a method for manufacturing a self-repairing optical waveguide in which opposing optical waveguides are connected to each other by a composite polymer containing a copolymer or a mixed polymer of a photopolymer and a self-repairing polymer, wherein the photopolymer is a polymer of one or more types of photopolymerizable monomers, and the self-repairing polymer is a polymer having a host group and a guest group and bonding through host-guest interaction, preparing a mixed composition including a photopolymer-forming composition that forms the photopolymer and a self-repairing polymer-forming composition that forms the self-repairing polymer; The prepared mixed composition is placed between the opposing optical waveguides, and then the photopolymer-forming composition and the self-healing polymer-forming composition are copolymerized or polymerized separately to form a mixed polymer, thereby forming the self-healing optical waveguide.

[0017] According to this invention, the manufactured self-healing optical waveguide contains a self-healing polymer having a molecular structure that has a host group and a guest group and is bonded through host-guest interaction, or a copolymer of a photopolymer and a self-healing polymer.Therefore, when reconnecting after cutting, the reversibility of the molecular structure of the self-healing polymer or copolymer allows the cut parts to be butted together to be reconnected by self-healing, thereby reforming the optical waveguide, without having to apply a photopolymer-forming composition to the cut part or irradiate light for a polymerization reaction as in the conventional case.

[0018] (7) In the method for manufacturing a self-repairing optical waveguide according to the present invention, the photopolymer-forming composition contains one or more photopolymerizable monomers, and the self-repairing polymer-forming composition is a polymer of a composition containing a host group-containing polymerizable monomer and a guest group-containing polymerizable monomer.

[0019] In this case, the photopolymer forming composition can be made of two or more photopolymerizable monomers, and by doing so, the mixing ratio can be adjusted depending on the photopolymerizability, flexibility, refractive index of the core and clad, and connection cross-sectional area of ​​the optical waveguide.

[0020] (8) In the method for manufacturing a self-repairing optical waveguide according to the present invention, the composition ratio of the core and the cladding that make up the self-repairing optical waveguide is changed by adjusting the blending ratio of the photopolymer-forming composition and the self-repairing polymer-forming composition. According to this invention, the composition ratio of the core and the cladding that make up the self-repairing optical waveguide can be changed by changing the blending ratio of the photopolymer-forming composition and the self-repairing polymer-forming composition, so that an increase in the contact cross-sectional area can be realized and connectivity can be improved.

[0021] (9) A method for reconnecting a self-repairing optical waveguide according to the present invention is a method for reconnecting a self-repairing optical waveguide formed between opposing optical waveguides by a composite polymer to connect the optical waveguides, wherein the composite polymer has a copolymer or a mixed polymer of an optical polymer and a self-repairing polymer, and the self-repairing polymer is a polymer of a monomer having a host group and a guest group and bonding by host-guest interaction, After the self-repairing optical waveguide that connects the optical waveguides is cut, the cut portions (cut sections) are simply butted together to be reconnected by self-repair, without the need to reapply the composition for forming the composite polymer or irradiate with light.

[0022] According to this invention, when reconnecting after disconnection, the self-healing polymer, which has a host group and a guest group and is bonded through host-guest interaction, exhibits reversible self-healing properties, enabling reconnection. This makes it possible to reconnect by self-healing simply by butting the disconnected parts together, thereby forming a self-healing optical waveguide again and reconnecting the parts, without having to apply a photopolymer-forming composition to the disconnected part or irradiate it with light for a polymerization reaction, as in the conventional case.

[0023] (10) The optical waveguide connection structure according to the present invention is characterized in that the self-repairing optical waveguide according to the present invention is provided between optical waveguides, or optical waveguides are reconnected to each other by the reconnection method for the self-repairing optical waveguide according to the present invention. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a self-healing optical waveguide, a manufacturing method thereof, and a reconnection method of a self-healing optical waveguide that can reconnect a disconnected self-healing optical waveguide simply by butting together the cut portions. More specifically, according to the present invention, facing optical waveguides are connected using a self-healing optical waveguide, which results in lower transmission loss and no optical axis misalignment due to vibration or the like compared to a connection method of optical waveguides connected using a connector with an optical adapter. Furthermore, even if the connection portion between optical waveguides is disconnected due to reasons such as periodic inspection of an optical communication system, the self-healing optical waveguide of the present invention can be reconnected by self-healing simply by butting together the cut portions to reform and reconnect the optical waveguide.

[0025] The self-repairing optical waveguide obtained by this invention can be reconnected without light irradiation after being cut during inspection, etc., thereby reducing the takt time, material costs, and energy required for inspection and repair. As a result, it can be preferably used as a replacement for connector structures and optical adapters that are expensive and difficult to align with optical axis misalignment. For example, a low-cost connection method can be provided that has low transmission loss and does not cause optical axis misalignment, even after cutting optical fibers used at a connection point for transmission at speeds over 10 gigabits using multimode optical fibers with a core diameter of approximately 50 μm. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is an example of a method for manufacturing a self-repairing optical waveguide according to the present invention. [Figure 2] 1 is an example of a method for reconnecting a self-repairing optical waveguide according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The self-repairing optical waveguide, its connection method, and its reconnection method according to the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and the present invention is not limited to only the following embodiment, and can be applied to applications and modifications within the scope of the gist thereof.

[0028] [Self-healing optical waveguide] The self-healing optical waveguide of the present invention is a self-healing optical waveguide formed between opposing optical waveguides using a composite polymer, characterized in that the composite polymer has a copolymer or mixed polymer of an optical polymer and a self-healing polymer, and the self-healing polymer is a polymer of monomers that have a host group and a guest group and are bonded through host-guest interaction.

[0029] Conventionally, optical fibers could be spliced ​​by polymerizing a photopolymer-forming composition (e.g., a photocurable resin) using light irradiated from an optical fiber. However, to reconnect optical fibers after they have been cut, the photopolymer-forming composition had to be reinjected between the cut optical fibers and light irradiated from the optical fiber again to polymerize the photopolymer-forming composition, resulting in a splice. This required many steps, was cumbersome, and unrealistic. The present inventors have discovered that by providing a self-repairing optical waveguide between the optical fibers, which is made of a composite polymer having a copolymer or mixed polymer of a photopolymer and a self-repairing polymer, it is possible to repeatedly cut and reconnect the optical fibers without having to reapply a photopolymer-forming composition or irradiate light between the cut optical fibers as in the past. The present invention was made based on this finding.

[0030] The self-repairing optical waveguide of this invention is a self-repairing optical waveguide formed by connecting optical waveguides (e.g., optical fibers) facing each other (optical fibers, planar optical waveguides, etc., hereinafter referred to as "optical fibers" for ease of understanding) with a composite polymer, and therefore has lower transmission loss than the current common method of connecting optical fibers with connectors connected using an optical adapter, and does not cause optical axis misalignment due to vibrations, etc. Furthermore, even if the connection between the optical fibers is cut due to reasons such as periodic inspection of the optical communication system, the self-repairing optical waveguide of this invention can self-repair by simply butting the cut parts together afterwards. Furthermore, the composite polymer comprises a copolymer or mixed polymer of a photopolymer and a self-healing polymer, and the self-healing polymer is a polymer of monomers that have host and guest groups and bond through host-guest interaction. Therefore, when the optical waveguide is first formed, the photopolymer-forming composition and the self-healing polymer composition can be copolymerized or polymerized to form a mixed polymer, and when reconnecting after disconnection, the self-healing polymer that has host and guest groups and bonds through host-guest interaction exhibits reversible self-healing properties, enabling reconnection. This allows the optical waveguide to be re-formed and reconnected by self-healing simply by butting the disconnected parts together, without the need to apply a photopolymer-forming composition to the disconnected part or irradiate it with light for polymerization, as in the conventional method.

[0031] Patent Document 2 proposes a polymer of a host-group-containing polymerizable monomer, a guest-group-containing polymerizable monomer, and a third polymerizable monomer capable of dissolving the host-group-containing polymerizable monomer and the guest-group-containing polymerizable monomer as an alternative material for self-healing adhesives. The present invention uses a self-healing polymer similar to that described in Patent Document 2 as one of the components for solving the above-mentioned problems of the present application. Self-healing of self-healing optical waveguides is achieved by reversible bonding via the structure of the self-healing polymer already present at the cut surface (structural elements of a polymer of monomers that bond via host-guest interactions having a host group and a guest group). Therefore, even if the cutting and reconnection are repeated two or more times, the connection can be achieved without reapplying a photopolymer-forming composition to the cut surface or irradiating it with light, as in the past. Therefore, the self-healing optical waveguide obtained by this invention can be reconnected without irradiating light after cutting during inspection, etc., thereby reducing the takt time, material costs, and energy required for inspection and repair. As a result, it can be preferably used as a replacement for connector structures and optical adapters that are expensive and difficult to align to correct optical axis misalignment. For example, it can provide a connection method that is low cost, has low transmission loss, and does not cause optical axis misalignment, even after cutting optical fibers used for transmission at speeds of over 10 gigabits using multimode optical fibers with a core diameter of approximately 50 μm at the connection point.

[0032] In the above, the meaning of "the composite polymer has a copolymer or mixed polymer of a photopolymer and a self-healing polymer" means that it may be a copolymer of the monomers in the composition for forming each polymer, or a mixed polymer in which each polymer is simply mixed or chemically bonded. Furthermore, in the case of a mixed polymer, self-healing of the self-healing optical waveguide is achieved by a polymer (self-healing polymer) of monomers that have host groups and guest groups and are bonded by host-guest interaction, but in the case of a copolymer, it is achieved by a structural element that achieves self-healing (the above-mentioned "structural element of a polymer of monomers that have host groups and guest groups and are bonded by host-guest interaction").

[0033] Each component will be explained in detail. In this application, "monomer" and "monomer compound" are used to mean the same thing, and "polymer" and "polymerized polymer" are also used to mean the same thing. "Photopolymerization" means polymerization by light, and simply "polymerization" also means polymerization by light or heat.

[0034] <Optical waveguide> An optical waveguide is an object in which the self-repairing optical waveguide of the present invention is formed. Specifically, it refers to an optical waveguide used in optical communications, such as an optical fiber or a substrate with an optical waveguide. Hereinafter, "optical waveguide" refers to a component such as an optical fiber or a planar optical waveguide, and the "self-repairing optical waveguide" of the present invention is provided between such optical waveguides to connect them, and the two are different entities. In the following, to avoid confusion between "optical waveguide" and "self-repairing optical waveguide," "optical waveguide" may be referred to as "optical fiber" for ease of understanding. Therefore, "optical fiber" will be described as "optical waveguide."

[0035] The "self-repairing optical waveguide" according to the present invention refers to a composite polymer that connects opposing optical waveguides. Note that the "optical waveguide connection structure" according to the present invention refers to a structure that includes opposing optical waveguides and a composite polymer provided between them, and is formed by providing the self-repairing optical waveguide according to the present invention between the optical waveguides, or by reconnecting optical waveguides using the self-repairing optical waveguide reconnection method according to the present invention.

[0036] The optical fiber is not particularly limited, but examples thereof include plastic optical fibers with a core diameter of 1 mm used at gigabit speeds in in-vehicle optical communication systems, and multimode optical fibers (glass or plastic) with a core diameter of approximately 50 μm used at speeds of over 10 gigabits. The planar optical waveguide also encompasses substrates with optical waveguides, and examples thereof include, but are not limited to, substrates with optical waveguides for multi-channel optical wiring that achieve high-speed transmission between chips and large-capacity communication, substrates with polymer optical waveguides capable of single-mode transmission, and substrates with optical waveguides in which optical wiring (optical waveguides) are formed directly on a substrate for flip-chip packaging. The self-repairing optical waveguide of the present invention can be disposed between optical fibers when connecting such optical fibers, between planar optical waveguides when connecting planar optical waveguides, or between an optical fiber and a planar optical waveguide when connecting them.

[0037] The self-repairing optical waveguide of the present invention can also be provided between an optical waveguide (such as an optical fiber or a substrate with an optical waveguide) and a general optical component. For example, it can be provided between an optical fiber and a light-receiving element or a light-emitting element to connect the two, or between an optical fiber and a relay connector to connect the two. General optical components may include, for example, a connection to an optical fiber terminated with a ferrule, or a connection between optical fibers terminated with a ferrule. In this way, the self-repairing optical waveguide of the present invention can be applied to connecting optical waveguides and optical components in optical communication systems.

[0038] <Composite polymer> The composite polymer is formed between the opposing optical waveguides, and the composite polymer constitutes the self-healing optical waveguide. The composite polymer includes a copolymer or a mixed polymer of an optical polymer and a self-healing polymer. The meanings of copolymer and mixed polymer have already been explained, and the optical polymer and the self-healing polymer, which will be explained in detail below, may be a copolymer obtained by copolymerization, or may be a mixture (mixed polymer) of the respective polymers.

[0039] (photopolymer) The photopolymer constitutes a composite polymer consisting of a copolymer or mixed polymer together with a self-healing polymer. The photopolymer may be any polymer that polymerizes upon irradiation with light, and is generally a polymer obtained by photopolymerizing a photopolymer-forming composition that is composed of a monomer, an oligomer, a photopolymerization initiator, a light absorber, and various additives (stabilizers, fillers, pigments, etc.). A monomer is an organic material that polymerizes to form a large molecule, while an oligomer is an organic material that is obtained by reacting several monomers in advance and that polymerizes to form a large molecule in the same way as the monomer. Monomers are usually conveniently used, but oligomers or a mixture of monomers and oligomers may also be used.

[0040] The monomers constituting the photopolymer-forming composition are preferably one or more photopolymerizable monomers, which include at least a radically polymerizable monomer or a cationically polymerizable monomer and a crosslinking agent that crosslinks these monomers.

[0041] Examples of radical polymerizable monomers include monofunctional acrylate monomers. Examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. In this specification, "(meth)acrylate" refers to both acrylate and methacrylate. In the examples described below, a crosslinkable bifunctional acrylic monomer is used as the photopolymerizable acrylate monomer.

[0042] The crosslinking agent for crosslinking the radical polymerizable monomer may be a polyfunctional acrylate having two or more functional groups per molecule capable of forming a covalent bond with the radical polymerizable monomer through radical polymerization. Examples of polyfunctional acrylates include bifunctional to hexafunctional acrylates. Examples of bifunctional acrylates include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethylene oxide-modified hexahydrophthalic acid di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, adamantane di(meth)acrylate, and 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene. Examples of trifunctional acrylates include trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, and tris(meth)acryloxyethyl isocyanurate. Examples of tetrafunctional acrylates include diglycerin tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate. Examples of pentafunctional acrylates include propionic acid-modified dipentaerythritol penta(meth)acrylate. Examples of hexafunctional acrylates include dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate. In addition, polyfunctional thiols and the like may also be used, and specific examples thereof include pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, trimethylolpropane tris(3-mercaptobutyrate), 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinane-2,4,6-trione, and the like.

[0043] Photopolymerization initiators are added to monomers and oligomers to initiate photopolymerization reactions, preventing them from easily undergoing polymerization. Photopolymerization initiators absorb light and become activated (excited), causing reactions such as cleavage, hydrogen abstraction, and electron transfer to generate reaction initiators such as radical molecules and hydrogen ions. The generated radical molecules and hydrogen ions attack oligomer and monomer molecules, causing three-dimensional polymerization and crosslinking reactions. By generating molecules of a certain size or larger through this reaction, the irradiated portion can change from a liquid state (monomer) to a solid state (polymer).

[0044] Examples of photopolymerization initiators that photopolymerize radically polymerizable monomers include halogenated hydrocarbon derivatives (e.g., compounds having a triazine skeleton, compounds having an oxadiazole skeleton, etc.), aromatic ketones, α-aminoalkylphenones, α-hydroxyketones, acylphosphine oxides, oxime esters, aromatic onium salts, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

[0045] The light absorber used in radical polymerization is not particularly limited as long as it absorbs light of the predetermined wavelength used in photopolymerization. Examples include, for example, various near-infrared absorbing dyes that readily absorb light in the wavelength bands of 650 nm or 850 to 980 nm used in optical communication systems. Specific examples include sensitizers such as dyes. Specific examples of such dyes include, but are not limited to, cyanine dyes, rhodamine dyes, coumarin dyes, squarylium dyes, immonium dyes, phthalocyanine dyes, and porphyrin dyes.

[0046] Examples of the cationically polymerizable monomer include monofunctional monomers having an epoxy group or an oxetanyl group. Specific examples of the monofunctional epoxy monomer include ethyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, t-butylphenyl glycidyl ether, and glycidyl lauryl ether. Examples of monofunctional oxetane monomers include 2-ethylhexyloxetane, 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane, 3-hydroxymethyl-3-normal butyloxetane, 3-hydroxymethyl-3-phenyloxetane, 3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane, 3-hydroxyethyl-3-ethyloxetane, 3-hydroxyethyl-3-propyloxetane, 3-hydroxyethyl-3-phenyloxetane, 3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane, 3-hydroxypropyl-3-phenyloxetane, and 3-hydroxybutyl-3-methyloxetane.

[0047] Examples of crosslinking agents that crosslink cationic polymerizable monomers include polyfunctional epoxies such as bifunctional and trifunctional epoxies. Examples of bifunctional epoxies include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, and 2,2-bis(4-glycidyloxyphenyl)propane. Examples of trifunctional epoxies include trimethylolpropane triglycidyl ether, tris(4-hydroxyphenyl)methane triglycidyl ether, glycerin triglycidyl ether, N,N,O-triglycidyl-p-aminophenol, N,N,O-triglycidyl-m-aminophenol, N,N,O-triglycidyl-4-amino-m-cresol, N,N,O-triglycidyl-5-amino-o-cresol, and 1,1,1-(triglycidyloxyphenyl)methane. In addition, polyfunctional oxetanes may also be used. Specifically, bifunctional oxetanes include xylylene bisoxetane, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,4-bis{[(3-ethyloxetan-3-yl)methoxy]methyl}bene, bis[1-ethyl(3-oxetanyl)]methyl ether, 1,2-bis[(3-ethyloxetan-3-yl)methyloxy]ethane, 1,3-bis[(3-ethyloxetane Examples of the methyloxycarbonyl alcohol include 1,4-bis[(3-ethyloxetan-3-yl)methyloxy]propane, 1,4-bis[(3-ethyloxetan-3-yl)methyloxy]butane, 1,5-bis[(3-ethyloxetan-3-yl)methyloxy]pentane, 1,6-bis[(3-ethyloxetan-3-yl)methyloxy]hexane, 1,7-bis[(3-ethyloxetan-3-yl)methyloxy]heptane, and 1,8-bis[(3-ethyloxetan-3-yl)methyloxy]octane.

[0048] Examples of the polymerization initiator for initiating cationic polymerization include sulfonium salt compounds, iodonium salt compounds, phosphonium salt compounds, ammonium salt compounds, antimonate compounds, diazonium salt compounds, selenium salt compounds, oxonium salt compounds, and bromine salt compounds.

[0049] The light absorber used in cationic polymerization is the same as the light absorber used in radical polymerization described above, and is not particularly limited as long as it is a light absorber that absorbs light of a predetermined wavelength used in photopolymerization, but examples include various near-infrared absorbing dyes that easily absorb light in the wavelength bands of 650 nm and 850 to 980 nm used in optical communication systems.Specific examples are also the same as the light absorbers used in radical polymerization described above, so their description will be omitted here.

[0050] The photopolymer-forming composition may contain other additives as desired within the range that does not impair the effects of the present invention. Examples of such additives include various additives such as stabilizers and fillers for the purposes of stabilization and reinforcement.

[0051] Such a photopolymer-forming composition may contain only one or two or more of the above-mentioned photopolymerizable monomers. Blending two or more photopolymerizable monomers is preferred because it allows for the photopolymerization, flexibility, and refractive index adjustment of the core and clad portions to be adjusted as desired. The blending ratio of the two or more photopolymerizable monomers can be adjusted as desired depending on the blending purpose, and can be set, for example, taking into account the flexibility and hardness of the composite polymer that constitutes the self-repairing optical waveguide.

[0052] (self-healing polymer) The self-healing polymer is a characteristic constituent material of the self-healing optical waveguide according to the present invention, and together with the optical polymer, it constitutes a composite polymer consisting of a copolymer or a mixed polymer. The self-healing polymer itself is a polymer of monomers having a host group and a guest group and bonded through host-guest interaction, as proposed in Patent Document 2. This self-healing polymer is obtained by polymerizing a self-healing polymer composition containing a host group-containing polymerizable monomer and a guest group-containing polymerizable monomer. This self-healing polymer composition may also contain a third polymerizable monomer that has the property of dissolving the host group-containing polymerizable monomer and the guest group-containing polymerizable monomer. Furthermore, the "bonding" in the host-guest interaction is thought to be a physical bonding mode.

[0053] A host group is a structural element capable of bonding with a guest group through host-guest interaction and forming an inclusion compound (clathrate complex) with the guest group. Specifically, the host group is a monovalent group obtained by removing one hydrogen atom or hydroxyl group from a cyclodextrin derivative. The removed hydrogen atom or hydroxyl group may be located at any site on the cyclodextrin derivative. From the viewpoint of facilitating the formation of a host group, the host group is preferably a monovalent group obtained by removing one hydroxyl group from a cyclodextrin derivative. Specific examples of cyclodextrin derivatives include at least one selected from the group consisting of α-cyclodextrin derivatives, β-cyclodextrin derivatives, and γ-cyclodextrin derivatives. Note that the cyclodextrin derivative referred to here refers to a molecule having a structure in which a cyclodextrin molecule is substituted with another organic group.

[0054] A cyclodextrin derivative has a structure in which at least one hydroxyl group of cyclodextrin is substituted with at least one group selected from the group consisting of a hydrocarbon group, an acyl group, and -CONHR (R is a methyl group or an ethyl group). For convenience, "at least one group selected from the group consisting of a hydrocarbon group, an acyl group, and -CONHR (R is a methyl group or an ethyl group)" is also referred to as "hydrocarbon group, etc."

[0055] The hydrocarbon group is not particularly limited, but examples thereof include alkyl groups, alkenyl groups, and alkynyl groups. The number of carbon atoms in the hydrocarbon group is not particularly limited, but is preferably 1 to 4, from the viewpoints of ease of dissolution in the third polymerizable monomer and ease of formation of host-guest interactions in the polymer. Specific examples of hydrocarbon groups having 1 to 4 carbon atoms include methyl groups, ethyl groups, propyl groups, and butyl groups. When the hydrocarbon group is a propyl group or a butyl group, it may be either linear or branched. The hydrocarbon group may have a substituent, as long as the effects of the present invention are not impaired. Examples of acyl groups include acetyl groups, propionyl groups, and formyl groups. The acyl group may further have a substituent. The acyl group is preferably an acetyl group, from the viewpoints of ease of dissolution in the third polymerizable monomer and ease of formation of host-guest interactions in the polymer. -CONHR (R is a methyl group or an ethyl group) is a methyl carbamate group or an ethyl carbamate group. As for --CONHR, it is also preferable that it is an ethyl carbamate group, from the viewpoints of ease of dissolving in the third polymerizable monomer and ease of forming host-guest interactions in the polymer.

[0056] The host group-containing polymerizable monomer is a compound having the host group described above and a polymerizable functional group. The host group is, for example, covalently bonded to the side chain of the host group-containing polymerizable monomer. The polymerizable functional group can be a radically polymerizable functional group, such as an acryloyl group (CH═CH(CO)—), a methacryloyl group (CH═CCH(CO)—), or a group containing a carbon-carbon double bond, such as a styryl group, a vinyl group, or an allyl group. These carbon-carbon double bond-containing groups may further have a substituent, provided that the radical polymerizability is not inhibited. Specific examples of the host group-containing polymerizable monomer include those described in Patent Document 2. For example, a vinyl-based polymerizable monomer containing a host group is preferred, and a (meth)acrylic acid ester derivative or a (meth)acrylamide derivative is preferred. The method described in Patent Document 2 can also be used to produce the host group-containing polymerizable monomer.

[0057] A guest group is a group that can bond with a host group through host-guest interaction and is a structural element that can form an inclusion compound (clathrate complex) with the host group. The type of guest group is not limited, and examples include linear or branched hydrocarbon groups having 3 to 30 carbon atoms, cycloalkyl groups, aryl groups, heteroaryl groups, and organometallic complexes, which may have one or more substituents. More specific examples of the guest group include linear or cyclic alkyl groups having 4 to 18 carbon atoms. The linear alkyl groups having 4 to 18 carbon atoms may be linear or branched. The cyclic alkyl groups may have a cage structure. Examples of the substituent include halogen atoms (e.g., fluorine, chlorine, bromine, etc.), hydroxyl groups, carboxyl groups, ester groups, amide groups, and optionally protected hydroxyl groups.

[0058] In addition to the above, the guest group may also include a monovalent group formed by removing one atom (e.g., a hydrogen atom) from at least one guest molecule selected from the group consisting of alcohol derivatives, aryl compounds, carboxylic acid derivatives, amino derivatives, azobenzene derivatives having a cyclic alkyl group or a phenyl group, cinnamic acid derivatives, aromatic compounds and their alcohol derivatives, amine derivatives, ferrocene derivatives, azobenzene, naphthalene derivatives, anthracene derivatives, pyrene derivatives, perylene derivatives, clusters composed of carbon atoms such as fullerene, and dansyl compounds. Further specific examples of the guest group include a t-butyl group, an n-octyl group, an n-dodecyl group, an isobornyl group, an adamantyl group, and the like.

[0059] The guest group-containing polymerizable monomer is a compound having the above-described guest group and a polymerizable functional group. The guest group is, for example, covalently bonded to the side chain of the guest group-containing polymerizable monomer. The polymerizable functional group is the same as that of the host group-containing polymerizable monomer. Specific examples of the guest group-containing polymerizable monomer include those described in Patent Document 2. For example, vinyl polymerizable monomers containing a guest group are preferred, and (meth)acrylic acid esters or derivatives thereof, and (meth)acrylamide or derivatives thereof are preferred. These are preferred because they facilitate polymerization reactions and also have excellent solubility in the third polymerizable monomer. The method described in Patent Document 2 can also be used as a method for producing the guest group-containing polymerizable monomer.

[0060] Specific examples of guest group-containing vinyl monomers include n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-dodecyl (meth)acrylate, adamantyl (meth)acrylate, hydroxyadamantyl (meth)acrylate, 1-(meth)acrylamidoadamantane, 2-ethyl-2-adamantyl (meth)acrylate, N-dodecyl (meth)acrylamide, t-butyl (meth)acrylate, 1-acrylamidoadamantane, N-(1-adamantyl) (meth)acrylamide, N-benzyl (meth)acrylamide, N-1-naphthylmethyl (meth)acrylamide, ethoxylated O-phenylphenol acrylate, phenoxy polyethylene glycol acrylate, isostearyl acrylate, nonylphenol EO adduct acrylate, isobornyl (meth)acrylate, etc. Acrylate compounds are particularly preferred.

[0061] The third polymerizable monomer is a monomer that is optionally blended into the self-healing polymer composition as needed. The third polymerizable monomer is also described in Patent Document 2 and has the property of dissolving the host group-containing polymerizable monomer and the guest group-containing polymerizable monomer. Examples of such a third polymerizable monomer include various vinyl polymerizable monomers, and it is preferable that the third polymerizable monomer contains a (meth)acrylic ester compound. Specific examples of the (meth)acrylic ester compound include water-insoluble (meth)acrylates such as 2-ethylhexyl acrylate, n-octyl acrylate, 2-methoxy acrylate, tetrahydrofurfuryl acrylate, and 2-phenylethyl acrylate; and water-soluble (meth)acrylates such as 4-hydroxybutyl acrylate. Examples of water-insoluble (meth)acrylates include 2-methoxy acrylate, tetrahydrofurfuryl acrylate, and 2-phenylethyl acrylate.

[0062] It is preferable that all of the (meth)acrylic ester compounds contained in the third polymerizable monomer are acrylate compounds. Furthermore, it is preferable that the (meth)acrylamide contained in the third polymerizable monomer is acrylamide, and it is preferable that all of the (meth)acrylamide derivatives contained in the third polymerizable monomer are acrylamide derivatives. By appropriately designing the type and combination of the third polymerizable monomer, it is possible to freely design the elasticity, strength, and hardness of the obtained self-healing polymer.

[0063] The self-repairing polymer can be obtained by preparing a monomer mixture containing at least a host group-containing polymerizable monomer and a guest group-containing polymerizable monomer, and then polymerizing the monomer mixture.

[0064] Composite polymers containing copolymers or blends of such self-healing polymers and the above-mentioned photopolymers have excellent self-healing properties and can also be imparted with elasticity, flexibility, and rigidity (strength) as needed. In particular, since the composite polymer contains a copolymer or blend of a photopolymer and a self-healing polymer that has a host group and a guest group and bonds via host-guest interaction, even if the composite polymer is cut, simply butting the cut surfaces together again creates a host-guest interaction between the butted cut surfaces, resulting in rebonding and achieving self-healing properties. Self-healing of self-healing optical waveguides is achieved by reversible bonding through the molecular structure (a molecular structure form that has a host group and a guest group and bonds via host-guest interaction) of the self-healing polymer already present at the cut surface. Therefore, even if the cutting and reconnection are repeated two or more times, the connection can be achieved without the need for conventional methods such as applying a photopolymer-forming composition to the cut surface or irradiating it with light.

[0065] (Photopolymer and self-healing polymer content) Regarding the content ratio of the photopolymer and the self-healing polymer, the ratio of the photopolymerizable monomer constituting the photopolymer to the sum of the host group-containing polymerizable monomer and the guest group-containing polymerizable monomer constituting the self-healing polymer is preferably within a monomer ratio range of 9.9:0.1 to 0.1:9.9. The content ratio (compounding ratio) of the photopolymer and the self-healing polymer thus formed can be adjusted as desired depending on the required properties of the composite polymer. For example, if the proportion of the photopolymer is increased, a self-healing polymer that can self-heal even at a small proportion can be selected, and if the proportion of the self-healing polymer is increased, a photopolymer that can photocure even at a small proportion can be selected. Note that in the examples described below, favorable self-healing results were obtained when the content ratio (compounding ratio) of the photopolymer and the self-healing polymer thus formed was approximately 1:0.67 (e.g., approximately 0.6 to 0.8) by mass.

[0066] Since the present invention relates to a self-healing optical waveguide that is applied to connecting optical waveguides used in optical communication systems, a core and a clad can be formed in the self-healing optical waveguide itself. The core is formed using a core mixture composition whose core refractive index is the same as the refractive index of the composite polymer after photopolymerization, and the clad is formed using a clad mixture composition whose clad refractive index is the same as the refractive index of the composite polymer after photopolymerization. Note that the mixture composition refers to a composition containing a photopolymer-forming composition that forms a photopolymer and a self-healing polymer-forming composition that forms a self-healing polymer.

[0067] The core and cladding are formed by first providing a core mixture composition between opposing optical fibers, and then photopolymerizing the core mixture composition with light irradiated from the optical fiber to produce a self-repairing core. The excess core mixture composition that has not yet polymerized (cured) is then removed. Next, a cladding mixture composition is provided around the core formed between the opposing optical fibers. The cladding mixture composition is then photopolymerized with light irradiated from the optical fiber to produce a self-repairing cladding. The excess cladding mixture composition that has not yet polymerized (cured) is then removed. In this way, a core and a cladding with different refractive indices can be formed as a self-repairing optical waveguide. The core mixture composition and the cladding mixture composition can be obtained by selecting materials that will result in the desired refractive index of the composite polymer after polymerization.

[0068] [Method of manufacturing a self-repairing optical waveguide] The method for manufacturing a self-healing optical waveguide according to the present invention is a method for manufacturing a self-healing optical waveguide in which opposing optical waveguides are connected by a composite polymer containing a copolymer or mixed polymer of a photopolymer and a self-healing polymer, wherein the photopolymer is a polymer of one or more types of photopolymerizable monomers, and the self-healing polymer is a polymer having a host group and a guest group and bonding through host-guest interaction, and is characterized by preparing a mixed composition containing a photopolymer-forming composition that forms the photopolymer and a self-healing polymer-forming composition that forms the self-healing polymer, and then providing the prepared mixed composition between the opposing optical waveguides, and then copolymerizing the photopolymer-forming composition and the self-healing polymer-forming composition or polymerizing each of them to form a mixed polymer to form the self-healing optical waveguide.

[0069] In this manufacturing method, a prepared mixed composition is placed between opposing optical waveguides, and then the photopolymer-forming composition and the self-healing polymer-forming composition are polymerized to form a self-healing optical waveguide. The produced self-healing polymer or copolymer of a photopolymer and a self-healing polymer has a molecular structure that has a host group and a guest group and is bonded through host-guest interaction. Therefore, when reconnecting after being cut, the reversibility of the molecular structure of the self-healing polymer or copolymer allows the cut ends to be butted together to reconnect through self-healing, thereby reforming the optical waveguide, without the need to apply a photopolymer-forming composition to the cut end or irradiate it with light for a polymerization reaction, as in the conventional method.

[0070] As mentioned in the description of the self-healing optical waveguide above, by using two or more photopolymerizable monomers as the photopolymer-forming composition that forms the photopolymer, the mixing ratio of the two or more photopolymerizable monomers can be adjusted depending on the photopolymerizability, flexibility, refractive index of the core and cladding, and connection cross-sectional area of ​​the self-healing optical waveguide.

[0071] Similarly, by adjusting the blending ratio of the photopolymer-forming composition and the self-healing polymer-forming composition, the composition ratio of the core and the clad that make up the self-healing optical waveguide after polymerization can be changed, thereby increasing the contact cross-sectional area and improving connectivity.

[0072] The components constituting the method for manufacturing a self-repairing optical waveguide have been described in the section explaining the self-repairing optical waveguide, and therefore will not be described here.

[0073] FIG. 1 illustrates an example of a method for manufacturing a self-repairing optical waveguide according to the present invention. As shown in FIG. 1, (1) a pair of optical fibers are arranged so that their tips face each other; (2) a mixed composition containing a photopolymer-forming composition and a self-repairing polymer-forming composition is provided in the gap between the opposing optical fibers (100 μm in the example of FIG. 1); and (3) light (851 nm in the example of FIG. 1) is irradiated from one or both of the opposing optical fibers to photopolymerize the mixed composition, forming a self-repairing optical waveguide composed of a copolymer or mixed polymer thereof. The self-repairing optical waveguide is formed by photopolymerization of the mixed composition as light irradiated from the tip of the optical fiber passes through the mixed composition. When light is irradiated from both tips of the opposing optical fibers, photopolymerization proceeds from the tips of both optical fibers, and the self-repairing optical waveguide automatically grows without misalignment from the tip of the optical fiber. As a result, loss due to optical axis misalignment, as occurs in conventional connector connections, does not occur. After photopolymerization, the unpolymerized portion remaining around the polymerized self-repairing optical waveguide is removed. In addition, the "50GI-fiber" in Figure 1 refers to a graded-index multimode optical fiber with a core diameter of 50 μm.

[0074] [Method for reconnecting self-repairing optical waveguides] The method for reconnecting a self-healing optical waveguide according to the present invention is a method for reconnecting a self-healing optical waveguide formed between opposing optical waveguides using a composite polymer to connect the optical waveguides together, wherein the composite polymer comprises a copolymer or mixed polymer of an optical polymer and a self-healing polymer, and the self-healing polymer is a polymer of monomers that have a host group and a guest group and bond through host-guest interaction, and after cutting the self-healing optical waveguide connecting the optical waveguides together, the cut portions (cut sections) are simply butted together to reconnect through self-healing, without reapplying a composition to form the composite polymer or irradiating light.

[0075] In this reconnection method, when reconnecting after disconnection, a molecular structure having a host group and a guest group that are bonded by host-guest interaction exhibits reversible self-repairing properties, enabling reconnection. This allows reconnection by self-repairing simply by butting the disconnected portions together, without the need to apply a photopolymer-forming composition to the disconnected portion or irradiate light for a polymerization reaction, as in the conventional method. A self-repairing optical waveguide can be formed and reconnected. Note that the components constituting this reconnection method were also described in the section describing the self-repairing optical waveguide above, and therefore will not be described here.

[0076] [Optical waveguide connection structure] The optical waveguide connection structure according to the present invention is (1) one in which the self-repairing optical waveguide according to the present invention is provided between optical waveguides, or (2) one in which optical waveguides are reconnected by the self-repairing optical waveguide reconnection method according to the present invention. Both (1) and (2) have a self-repairing optical waveguide provided between optical waveguides, and there is no difference in appearance between the two, but more specifically, (1) is the state before reconnection, and (2) is the state after reconnection. [Example]

[0077] The present invention will be described in detail below with reference to examples.

[0078] [Example 1] The mixed composition for forming the self-repairing optical waveguide contains a photopolymer-forming composition, a self-repairing polymer-forming composition, a photopolymerization initiator, and a light absorber. The photopolymer-forming composition contains a urethane acrylate monomer (product name: UV-3200B, manufactured by Mitsubishi Chemical Corporation, molecular weight: 10,000 Mw, number of oligomer functional groups: 2, Tg: -8°C), and the photopolymerization initiator contains P3B ([C 16 H 36 N]+[C 22 H 24The materials used were a near-infrared absorbing dye (product name: IRT, manufactured by Showa Denko K.K.) as a light absorber, a cyclodextrin (CD) derivative (product name: YNB-W13, manufactured by Yushiro Chemical Industry Co., Ltd.), an acrylate-based self-healing monomer, as a self-healing polymer-forming composition. These materials were mixed and stirred at room temperature for several hours to prepare a mixed composition for fabricating a self-healing optical waveguide. The mixing ratio of the mixed composition was photopolymer:self-healing polymer:photopolymerization initiator:light absorber = 1:0.67:0.005:0.0025 by mass.

[0079] Next, as shown in Figure 1, two 50 μm core diameter graded-index multimode optical fibers (50GI-fiber, OM4 standard, core diameter: 50 μm, cladding diameter: 125 μm) were placed facing each other with a 100 μm gap between them, and the prepared mixed composition was placed in the gap. Next, 851 nm laser light (output: 5 W, irradiation time: 10 seconds) was irradiated from both opposing optical fibers to polymerize the mixed composition, forming a self-healing optical waveguide with an outer diameter of 50 μm between the optical fibers. The unpolymerized excess mixed composition was then removed. In this way, the self-healing optical waveguide shown in Figure 2(A) was formed.

[0080] Next, the self-healing optical waveguide was cut and reconnected. The optical fibers sandwiching the self-healing optical waveguide were overstretched (Fig. 2(B)) to tear them apart, resulting in the configuration shown in Fig. 2(C). The cut ends were then simply butted together, and reconnected after one minute, as shown in Fig. 2(D). The reconnected waveguide, as shown in Fig. 2(E), was a stretchable, flexible self-healing optical waveguide. This cutting and reconnection was repeated 10 times, but the cutting force remained constant without any decrease. This confirmed that the reconnected connection strength was comparable to that of the initial state. Furthermore, the optical transmission loss after reconnection was evaluated and found to be similar to that of the initial state, confirming that low loss was maintained even after reconnection. The stretching and propagation loss measurements were performed using an optical axis stage alignment system composed of optical fiber alignment components from Suruga Seiki Co., Ltd. The optical axis stage alignment system was used to move the film horizontally (left and right in Figure 2) for stretching. [Industrial Applicability]

[0081] The present invention can be used in the optical communications industry, such as the automotive industry and IOWN (Innovative Optical and Wireless Network), as well as the TT equipment industry. It can also be applied to optical wiring connections using silicon photonics, for example, for inter-chip and intra-chip optical wiring connections in data centers or information processing devices (including PCs and smartphones).

Claims

1. A self-repairing optical waveguide formed between opposing optical waveguides using a composite polymer, wherein the composite polymer has a copolymer or mixed polymer of an optical polymer and a self-repairing polymer, and the self-repairing polymer is a polymer of a monomer having a host group and a guest group and bonding through host-guest interaction.

2. The self-repairing optical waveguide of claim 1, wherein the photopolymer is a polymer of one or more types of photopolymerizable monomers, and the self-repairing polymer is a polymer of a composition having a host group-containing polymerizable monomer and a guest group-containing polymerizable monomer.

3. The self-healing optical waveguide according to claim 2, wherein the photopolymerizable monomer constituting the photopolymer and the total of the host group-containing polymerizable monomer and the guest group-containing polymerizable monomer constituting the self-healing polymer are in a monomer ratio within the range of 9.9:0.1 to 0.1:9.

9.

4. The self-repairing optical waveguide according to claim 1 or 2, wherein the photopolymer is formed by photopolymerizing a photopolymer-forming composition containing one or more photopolymerizable monomers, a photopolymerization initiator, and a light absorber.

5. 3. The self-repairing optical waveguide according to claim 1, wherein the two or more photopolymerizable monomers are blended in a ratio that depends on the photopolymerizability, flexibility, refractive index of the core and clad, and connection cross-sectional area of ​​the optical waveguide.

6. A method for manufacturing a self-repairing optical waveguide in which opposing optical waveguides are connected with a composite polymer containing a copolymer or a mixed polymer of an optical polymer and a self-repairing polymer, comprising: the photopolymer is a polymer of one or more types of photopolymerizable monomers, and the self-repairing polymer is a polymer having a host group and a guest group and bonded through host-guest interaction; preparing a mixed composition including a photopolymer-forming composition that forms the photopolymer and a self-repairing polymer-forming composition that forms the self-repairing polymer; A method for manufacturing a self-repairing optical waveguide, characterized in that the prepared mixed composition is placed between the opposing optical waveguides, and then the photopolymer forming composition and the self-repairing polymer forming composition are copolymerized or polymerized separately to form a mixed polymer, thereby forming the self-repairing optical waveguide.

7. The method for producing a self-repairing optical waveguide according to claim 6, wherein the photopolymer-forming composition has one or more photopolymerizable monomers, and the self-repairing polymer-forming composition is a polymer of a composition having a host group-containing polymerizable monomer and a guest group-containing polymerizable monomer.

8. 8. The method for producing a self-repairing optical waveguide according to claim 6 or 7, wherein the composition ratio of the core and the clad constituting the self-repairing optical waveguide is changed by adjusting the blending ratio of the photopolymer forming composition and the self-repairing polymer forming composition.

9. A method for reconnecting a self-repairing optical waveguide formed between opposing optical waveguides and made of a composite polymer to connect the optical waveguides, comprising: The composite polymer comprises a copolymer or a mixed polymer of a photopolymer and a self-healing polymer, and the self-healing polymer is a polymer of a monomer having a host group and a guest group and bonded by host-guest interaction; A method for reconnecting a self-repairing optical waveguide, characterized in that after cutting the self-repairing optical waveguide that connects the optical waveguides together, the cut parts are simply butted together to be reconnected by self-repair, without reapplying a composition for forming the composite polymer or irradiating light.

10. 10. A connection structure of optical waveguides, characterized in that the self-repairing optical waveguide according to claim 1 is provided between optical waveguides, or optical waveguides are reconnected to each other by the reconnection method of the self-repairing optical waveguide according to claim 9.

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