JP2005062364A - Self-forming optical waveguide and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate formation of a self-forming optical waveguide that has small transmission loss without using a solvent. <P>SOLUTION: A first curing resin liquid 1 is filled in an acrylic transparent container 3 which is shaped to have an opening on the upper face of the rectangular parallelepiped and a plastic optical fiber is immersed, as shown in (a). The first curing resin liquid 1 is irradiated with a laser beam through the plastic optical fiber 4 and gradually hardened with the laser beam to form an axial core 5 through self convergence of light (b). From the opening of the transparent container 3, the uncured first curing resin liquid 1 is removed. In this case, the uncured first curing resin liquid 11 sticks to the surface of the core 5 and the inner face of the transparent container 3 and remains therein, as shown in (c). Then, a second curing resin liquid 2 is filled in the transparent container 3. In this case, the uncured first curing resin liquid 11 is dispersed in the second curing resin liquid 2. Thereafter, the second curing resin liquid 2 is photoset by ultraviolet rays to form a clad (d). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a self-forming optical waveguide having a columnar core obtained by curing a photocurable resin liquid. In the present invention, the photocurable resin liquid refers to a mixture of a photopolymerizable monomer, a photopolymerizable macromonomer or a photopolymerizable oligomer, and a photoinitiator.

An optical waveguide using a light-curing resin liquid irradiated with light from an optical fiber or the like to form a column-shaped cured product by a self-condensing phenomenon and using this as a core is described in Patent Document 1 and Patent Document 2. Yes. In these techniques, it is necessary to remove the uncured photocurable resin liquid around the core, and it has been proposed to use a solvent such as toluene. In addition, the present inventors developed a technique disclosed in Patent Document 3 below and received a patent (Japanese Patent No. 3444352). This technology introduces light that cures the photocurable resin liquid into the photocurable resin liquid through an optical fiber, and cures the columnar resin from the tip of the optical fiber to the diameter of the core of the optical fiber. The preferred conditions for forming the product are disclosed. After this, by removing the uncured photocurable resin liquid and surrounding the periphery with a resin having a lower refractive index, it is possible to easily form a module or the like using the previously formed resin cured product having a higher refractive index as an optical waveguide. Can be formed. It is easier to introduce light that cures only the high refractive index photocurable resin liquid into the mixed solution of the high refractive index photocurable resin liquid and the low refractive index photocurable resin liquid through an optical fiber. It was also disclosed in Patent Document 3 to form a columnar resin cured product.
JP-A-8-320422 JP-A-11-326660 JP 2000-347043 A

  When forming a columnar resin cured product using a high refractive index photocurable resin liquid without using a mixed solution of a high refractive index photocurable resin liquid and a low refractive index photocurable resin liquid, After removing the photocurable resin liquid having the refractive index as completely as possible, it is necessary to fill the container or the like with another photocurable resin having a lower refractive index. When uncured high-refractive-index photocurable resin liquid remains on the outer periphery of the core, particularly when uncured high-refractive-index photocurable resin liquid remains at the connection between the container and the core and the whole is cured. The shape of the core is different from the design in this part.

  More specifically, when an attempt is made to form a self-forming optical waveguide as shown in FIG. 7A by combining a total reflection mirror, a half mirror, or a dichroic mirror, an uncured high refractive index is formed after the core 5 is formed. If the photo-curing resin liquid 11 is not completely removed, as shown in FIG. 7B, the shape of the total reflection mirror 7, the half mirror 6, or the junction between the dichroic mirror and the core 5 is designed. It can be quite different. However, the photocurable resin liquid generally has a high viscosity, and the uncured photocurable resin liquid adheres to the cured core portion due to surface tension, and removal is never easy. Incomplete removal causes the following problems.

  First, when the uncured photocurable resin liquid is cured after the uncured photocurable resin liquid is embedded in the core portion and then the uncured photocurable resin liquid is cured, unevenness is formed on the core surface, resulting in a large scattering loss. Become. Excessive loss such as branch loss increases in the complicated part of the branch. Note that the possibility of remaining in the branched portion becomes a problem even when the viscosity of the photocurable resin liquid is small. Furthermore, even if uncured photo-curable resin liquid is not attached to the core, stray light may be scattered if it remains inside the housing or other optical components, or clad from the housing or optical components. Causes peeling, and has a considerable adverse effect on communication characteristics, leading to a decrease in reliability.

  By the way, when the solvent is used, the following adverse effects also occur. First, an increase in the process of filling with solvent, washing and drying occurs. Since the core member may swell due to the solvent and may cause deformation, the characteristics deteriorate. When the solvent enters the interface, the optical components, the core, and the casing are peeled off and easily broken. Optical properties are deteriorated by the penetration of the solvent into the core.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to easily form an optical waveguide using self-condensing properties without using a solvent.

The invention according to claim 1 is a self-forming optical waveguide having at least a part of a columnar core and a periphery thereof covered with a clad having a low refractive index, and the resin forming the core is photocured at a certain wavelength. A cured product of the first curable resin liquid that can be formed, and the resin that forms the clad is mainly different in composition from the first curable resin liquid and is compatible with the first curable resin. 2 is a cured product of the first curable resin liquid, both the first curable resin liquid and the second curable resin liquid have a viscosity of 1500 mPa · s or less, and the solubility parameter of the first curable resin liquid The difference in solubility parameter between the second curable resin liquid and the second curable resin liquid is 4.4 MPa ^1/2 or less. There is substantially no lower limit for the difference in viscosity and solubility parameter, and it may be selected within a common sense range.

  The invention according to claim 2 is a self-forming optical waveguide in which at least a part of the core is a columnar core and the periphery thereof is covered with a clad having a low refractive index, and the resin forming the core is at a certain wavelength. The cured product of the first curable resin liquid that is photocurable, and the resin that forms the clad is mainly a cured product of the second curable resin liquid that has at least a composition different from that of the first curable resin liquid. And the difference between the specific gravity of the first curable resin liquid and the specific gravity of the second curable resin liquid is 0.14 or more. Although there is no substantial upper limit for the difference in specific gravity, it is selected within a common sense range.

  According to a third aspect of the present invention, the core has a branching or bending portion at the joint with the total reflection mirror, half mirror, or dichroic mirror. The invention described in claim 4 is characterized in that the second curable resin liquid is a photocurable resin.

The invention according to claim 5 is a method of manufacturing a self-forming optical waveguide in which at least a part is a columnar core and the periphery thereof is covered with a clad having a low refractive index, at a wavelength in a desired container. A step of adding a photocurable first curable resin liquid, a step of irradiating the first curable resin liquid with light and photocuring to form at least a part of a columnar core; After forming the core of the shape, a step of taking out most of the uncured first curable resin liquid out of the container, and a container having a core that is a cured product of the first curable resin liquid are first. The curable resin liquid at least has a composition different from that of the first curable resin liquid that is compatible with the first curable resin and is filled with the second curable resin liquid remaining in the container. In the second curable resin liquid, and an uncured first curable resin And a step of curing the second curable resin liquid, both of the first curable resin liquid and the second curable resin liquid have a viscosity of 1500 mPa · s or less, and the first curable resin liquid The difference between the solubility parameter of the liquid and the solubility parameter of the second curable resin liquid is 4.4 MPa ^1/2 or less. The viscosity is the viscosity at the temperature when filling the second curable resin liquid. There is substantially no lower limit for the difference in viscosity and solubility parameter, and it may be selected within a common sense range. The invention described in claim 6 is a modified invention of the invention described in claim 5, in which the core is removed after the step of taking out most of the uncured first curable resin liquid out of the container. It is taken out and incorporated in another container, and in the other container in which the core is incorporated, the process after the step of filling the second curable resin liquid is performed in the same manner as in the invention described in claim 5.

  The invention according to claim 7 is a method of manufacturing a self-forming optical waveguide in which at least a part is a columnar core and its periphery is covered with a clad having a low refractive index, at a wavelength in a desired container. A step of adding a photocurable first curable resin liquid, a step of irradiating the first curable resin liquid with light and photocuring to form at least a part of a columnar core; After forming the core of the shape, a step of taking out most of the uncured first curable resin liquid out of the container, and a container having a core that is a cured product of the first curable resin liquid are first. A second curable resin liquid having at least a composition different from that of the curable resin liquid is filled, and the uncured first curable resin liquid remaining in the container is placed above the container by the second curable resin liquid. Or a step of moving downward, an uncured first curable resin liquid, and a second hard resin. And a step of curing the sexual resin liquid, the difference in the specific gravity of the first curable resin liquid specific gravity and a second curable resin liquid is equal to or is less than 0.14. Although there is no substantial upper limit for the difference in specific gravity, it is selected within a common sense range. The invention described in claim 8 is a modified invention of the invention described in claim 7, in which the core is removed after the step of taking out most of the uncured first curable resin liquid out of the container. It is taken out and incorporated in another container, and in the other container in which the core is incorporated, the process after the step of filling the second curable resin liquid is performed in the same manner as in the eighth aspect of the invention.

  The invention according to claim 9 is the invention according to claim 5 or 7, wherein at least one of a total reflection mirror, a half mirror, or a dichroic mirror is arranged in the container to form a columnar core. In the process, a junction between the total reflection mirror, half mirror, or dichroic mirror and the core is formed, and a branch of the core or a bent portion of the core is formed. Further, in the invention described in claim 10, in the invention described in claim 6 or 8, at least one of a total reflection mirror, a half mirror, and a dichroic mirror is disposed in the container for forming the core. In the step of forming the columnar core, a junction between the total reflection mirror, half mirror, or dichroic mirror and the core is formed, and a branch of the core or a bent portion of the core is formed, and the core is taken out into another container. In the assembling step, the total reflection mirror, half mirror, or dichroic mirror and the branch of the core or the bent portion of the core are taken out and integrated into another container.

  The invention described in claim 11 is characterized in that the second curable resin liquid is a photocurable resin.

[Action]
If the viscosity of the second curable resin liquid is low and the compatibility with the uncured first curable resin liquid is high, the uncured first curable resin liquid attached to the core surface or the inner surface of the container is: When the second curable resin liquid is poured into the container, it diffuses into the second curable resin liquid without remaining on the core surface or the inner surface of the container. Further, even when the uncured first curable resin liquid does not diffuse into the second curable resin liquid, the uncured first curable resin liquid is the second if the specific gravity is greatly different. It is driven up or down the curable resin liquid and cannot remain on the core surface.

When the viscosity of the second curable resin liquid is low and the compatibility with the uncured first curable resin liquid is high, it is removed by dissolving and diffusing the uncured first curable resin liquid from the core surface. (Claims 1, 5, 6). Moreover, when the specific gravity differs greatly, in any case, the uncured first curable resin liquid can be removed from the core surface (claims 2, 7 and 8). These effects are particularly effective when an optical waveguide is formed by curing a viscous curable resin liquid in a container having a relatively small internal volume of 1 to several cm ³ . If the second curable resin liquid is a photocurable resin, it can be cured together with the remaining uncured first curable resin liquid (claims 4 and 11). The present invention is particularly suitable for an optical waveguide having a branched or bent portion (reflecting portion) having a total reflection mirror, a half mirror, a dichroic mirror, and the like, and a method for manufacturing the same (claims 3, 9, 10).

  Hereinafter, specific examples of the present invention will be described. However, the present invention is not limited to the following examples.

Each of the core materials shown in Table 1 is a photocurable first curable resin liquid, and the second curable resin liquid is 8 parts by weight of OXT-221 manufactured by Toagosei Co., Ltd. An optical waveguide was prepared as follows using a mixture of 2 parts by weight of UVR-6110 manufactured by Union Carbide Corporation. In Table 1, the value of the dissolution parameter is simply “SP value”. In the following, the SP value indicates the solubility parameter. The second curable resin liquid has a viscosity of 120 mPa · s, SP value from Toagosei Co., Ltd. OXT-221 SP value 18.25 MPa ^1/2 and Union Carbide UVR-6110 SP value 23.44 MPa ^1/2 19.28 MPa ^1/2 was calculated. Here, the solubility parameter was calculated | required by the calculation method of Small et al. Described in Polymer Handbook 4th edition pp.682-685 published by Wiley International Co., Ltd., and data for the calculation (same book same page, table 1-3). The monomer of OXT-221 is di (1-ethyl (3-oxetanyl)) methyl ether, the monomer of UVR-6110 is 3,4-epoxycyclohexanecarboxylic acid-3,4-epoxycyclohexylmethyl, and OXT -221 contains a photopolymerization initiator.

図１は本願発明に係る光導波路１０の製造工程を示す工程図（断面図）である。まず、図１の（ａ）のように、直方体の上面が開口となった形のアクリル製の透明容器３に第１の硬化性樹脂液１を充填し、プラスチック光ファイバ４を浸漬した。プラスチック光ファイバ４はコア径980μm、開口数0.25のものを用いた。次に、このプラスチック光ファイバ４を通して波長488nmのレーザ光を第１の硬化性樹脂液１に照射した。レーザ光の出射光強度は100mWとした。また、波長488nmは、各第１の硬化性樹脂液１の有する光重合開始剤のいずれもが活性化される波長として選択された。こうして第１の硬化性樹脂液１に照射されたレーザ光により徐々に硬化し、自己集光性によって軸状のコア５が形成された。本実施例では、長さ15mmのコア５の形成をもって透明容器３の壁に到達した（図１の（ｂ））。

FIG. 1 is a process diagram (cross-sectional view) showing a manufacturing process of an optical waveguide 10 according to the present invention. First, as shown in FIG. 1A, an acrylic transparent container 3 having a rectangular parallelepiped upper surface was filled with the first curable resin liquid 1, and the plastic optical fiber 4 was immersed therein. A plastic optical fiber 4 having a core diameter of 980 μm and a numerical aperture of 0.25 was used. Next, the first curable resin liquid 1 was irradiated with laser light having a wavelength of 488 nm through the plastic optical fiber 4. The emitted light intensity of the laser beam was 100 mW. Further, the wavelength 488 nm was selected as the wavelength at which any of the photopolymerization initiators of each first curable resin liquid 1 was activated. In this way, the first curable resin liquid 1 was gradually cured by the laser light irradiated, and the shaft-like core 5 was formed by self-condensing property. In the present example, the formation of the core 5 having a length of 15 mm reached the wall of the transparent container 3 ((b) in FIG. 1).

  Next, the uncured first curable resin liquid 1 was removed from the opening of the transparent container 3. At this time, since the cleaning using a solvent or the like was not performed, most of the first curable resin liquid 1 could be removed, but the surface of the core 5 and the inner surface of the transparent container 3 as shown in FIG. A part of the uncured first curable resin liquid 11 adhered to and remained. Next, the transparent container 3 was filled with the second curable resin liquid 2. At this time, the uncured first curable resin liquid 11 is dispersed in the second curable resin liquid 2. Thereafter, the second curable resin liquid 2 was photocured using ultraviolet light to form a clad. At this time, the uncured first curable resin liquid 11 dispersed in the second curable resin liquid 2 was also photopolymerized and integrated into a cured product 22 ((d) in FIG. 1). .

The transmission loss of the optical waveguide 10 thus formed is measured, and the relationship between the viscosity of the first curable resin liquid 1 and the difference between the SP values of the first and second curable resin liquids is examined. It was. FIG. 2 is a graph showing the relationship between the viscosity of the first curable resin liquid 1 and the transmission loss of the optical waveguide 10, and FIG. 3 shows the SP value difference between the first and second curable resin liquids and the optical waveguide 10. FIG. 4 is a graph showing the relationship between the viscosity of the first curable resin liquid 1 and the SP value difference between the first and second curable resin liquids. In FIG. 2 to FIG. 4, black circles indicate good cases where the transmission loss is 1 dB / cm or less, and crosses (×) indicate cases where the transmission loss exceeds 1 dB / cm. A clear index cannot be obtained from FIGS. 2 and 3, and the transmission loss of the optical waveguide 10 is determined only from the viscosity of the first curable resin liquid 1 and only from the SP value difference between the first and second curable resin liquids. It is not possible to specify a range with a small amount. However, as shown in FIG. 4, by combining the viscosity of the first curable resin liquid 1 and the SP value difference between the first and second curable resin liquids, the viscosity of the first curable resin liquid 1 is It was found that the transmission loss of the optical waveguide 10 can be made 1 dB / cm or less when the SP value difference between the first and second curable resin liquids is 1500 mPa · s or less and the SP value difference is 4.4 MPa ^1/2 or less. That is, the uncured first curable resin liquid 11 adhering to the core 5 or the like is easily dispersed in the second curable resin liquid 2 because of low viscosity and good compatibility. Conversely, if any of the viscosity is high or the compatibility is poor, the uncured first curable resin liquid 11 attached to the core 5 or the like is easily dispersed in the second curable resin liquid 2. First, it hardens while adhering to the core 5 and the like, and the scattering loss on the surface increases. 4 that the viscosity is more preferably 1000 mPa · s or less. Furthermore, when the viscosity is xmPa · s and the SP value difference is yMPa ^1/2 , the viscosity xmPa · s and the SP value difference yMPa ^1/2 may be adjusted within the range of x / 1500 + y / 9 ≦ 1. Understand.

  Corresponding to the above experiments, after forming the core 5 having a length of 15 mm, the uncured first curable resin liquid 1 is removed by ultrasonic cleaning using isopropyl alcohol, and then the transparent container 3 is formed. Transmission loss was measured for an optical waveguide formed by filling the second curable resin liquid 2 and curing it. At this time, in any of the first curable resin liquids 1, the transmission loss is as small as 0.2-0.5 dB / cm, and high transmission loss as shown in Table 1 and FIGS. This is considered to be due to the influence of the first curable resin liquid 11 and its cured product.

  Using the first curable resin liquid 1 forming the core as shown in Table 2 and the second curable resin liquid 2 forming the clad, the optical waveguide 10 is formed in the same manner as in the first embodiment, and transmission loss is achieved. Was measured. The results are shown in Table 2 and FIGS. FIG. 5 shows the relationship between the refractive index and specific gravity of the first curable resin liquid 1 and the second curable resin liquid 2 before curing. In this example, Defender OP-38, 40, 43, 44, 47 manufactured by Dainippon Ink was used as the fluorinated acrylic monomer. These are fluorine-substituted acrylic monomers, and the defender OP-38 has the largest fluorine substitution amount, and the fluorine substitution amount decreases in the order of the defenders OP-40, 43, 44, and 47. For this reason, those having a large amount of fluorine substitution have a low refractive index and a high specific gravity. This is shown in FIG.

ディフェンサＯＰ−４７を第１の硬化性樹脂液１としてコアを形成し、第２の硬化性樹脂液２としてディフェンサＯＰ−３８、４０、４３、４４を用いて光導波路を作成したときの伝送損失について、第１の硬化性樹脂液１と第２の硬化性樹脂液２の比重の差との関係を図６に示す。比重の差が0.14を超えると伝送損失が1dB/cmを下回り、良好な結果が得られた。このとき、第１の硬化性樹脂液１と第２の硬化性樹脂液２はいずれも粘度が高いので、残存する未硬化の第１の硬化性樹脂液１１の第２の硬化性樹脂液２への分散は起こらなかったものと考えられる。また、比重差0.2以上で伝送損失は0.5dB/cm以下、比重差0.24以上で伝送損失は0.35dB/cm以下、比重差0.3以上で伝送損失は0.25dB/cm以下となる傾向が見られる。よって、比重差0.2以上が更に好ましく、比重差0.24以上がより好ましい。

Transmission loss when an optical waveguide is formed using the defender OP-47 as the first curable resin liquid 1 and the core as the second curable resin liquid 2 and using the defenders OP-38, 40, 43, and 44. 6 shows the relationship between the specific gravity difference between the first curable resin liquid 1 and the second curable resin liquid 2. When the difference in specific gravity exceeded 0.14, the transmission loss was less than 1 dB / cm, and good results were obtained. At this time, since both the first curable resin liquid 1 and the second curable resin liquid 2 have high viscosity, the second curable resin liquid 2 of the remaining uncured first curable resin liquid 11 is used. It is considered that no dispersion occurred. In addition, when the specific gravity difference is 0.2 or more, the transmission loss tends to be 0.5 dB / cm or less, when the specific gravity difference is 0.24 or more, the transmission loss is 0.35 dB / cm or less, and when the specific gravity difference is 0.3 or more, the transmission loss tends to be 0.25 dB / cm or less. Therefore, a specific gravity difference of 0.2 or more is more preferable, and a specific gravity difference of 0.24 or more is more preferable.

  In each of the above embodiments, a photocurable resin is used as the second curable resin liquid. However, the second curable resin liquid may be a thermosetting liquid, for example.

  As a monomer which performs radical photopolymerization, (meth) acrylic acid ester and (meth) acrylic acid amide are preferable. Specifically, monofunctional (meth) acrylic acid esters (mono (meth) acrylates) such as 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-butoxyethyl (meth) acrylate are used. Can do. Further, an ester (di (meth) acrylate) of diol such as ethylene glycol, neopentyl glycol, 1,6-hexanediol and 2 equivalents of (meth) acrylic acid can be used. Similarly, an ester (tri, tetra,... (Meth) acrylate) of an organic compound having a plurality of alcoholic hydroxyl groups and (meth) acrylic acid can be used. In these monomers, a part of methyl hydrogen, methylene hydrogen and methine hydrogen in the (meth) acryloyl group and other organic skeletons may be substituted with halogen. These monomers may be used in appropriate combinations.

  As the oligomer (macromonomer) for performing radical photopolymerization, a urethane-based oligomer, a polyether-based oligomer, an epoxy-based oligomer, a polyester-based oligomer having a (meth) acryloyl group at the terminal or branch is preferable. In these oligomers, a part of methyl hydrogen, methylene hydrogen, and methine hydrogen in the (meth) acryloyl group and other organic skeletons may be substituted with halogen. Moreover, you may use what combined these oligomers with the said monomer suitably.

  As a radical photopolymerization initiator, 2,2-dimethoxy-2-phenylacetophenone as a benzyldimethyl ketal compound, 2-hydroxy-2-methyl-phenylpropan-1-one as an α-hydroxyketone compound, (1 -Hydroxycyclohexyl) -phenyl ketone, α-aminoketone compounds include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-methyl-1- (4- (methylthio) ) Phenyl) -2-morpholinopropan-1-one, and bisacylphosphine oxide compounds include bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (2,4,6). -Trimethylbenzoyl) -phenylphosphine oxide, metallose Bis (η-cyclopentadienyl) -bis (2,6-difluoro-3- (N-pyroyl) phenyl) titanium or the like can be used as the silver compound. A plurality of these may be used.

  As the monomer or oligomer for performing cationic photopolymerization, monomers or oligomers such as an epoxy ring, an oxetane ring, a compound having a cyclic ether, a cyclic lactone compound, a cyclic acetal compound, and a vinyl ether compound can be used. Moreover, you may use what combined these monomers or oligomers appropriately.

  As a photocationic polymerization initiator, 4,4′-bis (di (2-hydroxyethoxy) phenylsulfonio) phenyl sulfide dihexafluoroantimonic acid, η-cyclopentadienyl-η-cumene iron (1 +)-hexa Fluorophosphoric acid (1-) or the like can be used.

  A photosensitizer may be added to the above-mentioned photo radical polymerization initiator or photo cationic polymerization initiator. Furthermore, a polymerization inhibitor, an ultraviolet absorber, a light stabilizer, an antioxidant, a leveling agent, an antifoaming agent and other additives can be blended as necessary. By the combination as described above, the photocurable liquid resin composition used in the present invention can be obtained. Further, the present invention does not exclude a combination of a photoanion polymerizable polymerization initiator and a monomer or oligomer. Further, polymerization by thiol-ene addition may be used. Similarly to the present invention, the core portion can be formed by light irradiation, and the clad portion can be formed by a method other than light irradiation.

  The time from filling the second curable resin liquid to curing is preferably about 10 minutes or less. This is to prevent the uncured second curable resin liquid from penetrating into the core (cured first curable resin liquid) and further swelling of the core.

  In the second embodiment, as shown in FIG. 7B, when the terminal end 51 of the core 5 is combined with the light receiving element or the light emitting element 8 mainly on the lower surface of the transparent container 3, the second curable resin liquid is used. Uses a material having a high specific gravity, removes the uncured first curable resin liquid 1 upward, and uncures from the vicinity of the end 51 of the core 5 coupled to the light receiving element or the light emitting element 8 on the lower surface of the transparent container 3. It is preferable that the first curable resin liquid 1 is easily removed.

  The refractive index after curing of the second curable resin liquid is desirably lower than the refractive index of the uncured first curable resin liquid. The shaft-shaped core formed by self-condensing property confines transmission light due to the difference in refractive index from the uncured first curable resin liquid, so that radiation loss due to the small difference in refractive index is reduced. In order to avoid this, it is desirable that the refractive index after curing of the second curable resin liquid is lower than the refractive index of the uncured first curable resin liquid.

Process drawing (sectional drawing) which shows the manufacturing process of the optical waveguide which concerns on this invention. The graph which shows the relationship between the viscosity of a 1st curable resin liquid, and the transmission loss of an optical waveguide. The graph which shows the relationship between SP value difference of the 1st and 2nd curable resin liquid, and the transmission loss of an optical waveguide. The graph which shows the relationship between the viscosity of a 1st curable resin liquid, and SP value difference of a 1st and 2nd curable resin liquid. The graph which shows the refractive index and specific gravity of a monomer in 2nd Example. The graph which shows the relationship between the specific gravity difference of the 1st and 2nd curable resin liquid, and the transmission loss of an optical waveguide. (A) is sectional drawing of an optical module, (b) is the intermediate figure of the work process in case washing | cleaning is not enough.

Explanation of symbols

1: Uncured first curable resin liquid 11: Remaining uncured first curable resin liquid 2: Uncured second curable resin liquid 22: Clad (cured second curable resin liquid)
3: Transparent container 4: Plastic optical fiber 5: Core (first curable resin liquid cured in a shaft shape)
6: Half mirror
7: Total reflection mirror

Claims (11)

A self-forming optical waveguide having at least a part of a columnar core and its periphery covered with a clad having a low refractive index,
The resin forming the core is a cured product of a first curable resin liquid that can be photocured at a certain wavelength,
The resin forming the clad is mainly a cured product of a second curable resin liquid having a composition different from that of the first curable resin liquid and having compatibility with the first curable resin.
Both the first curable resin liquid and the second curable resin liquid have a viscosity of 1500 mPa ⁴ s or less,
A difference between the solubility parameter of the first curable resin liquid and the solubility parameter of the second curable resin liquid is 4.4 MPa1 ^{/ 2} or less. A self-forming optical waveguide having at least a part of a columnar core and its periphery covered with a clad having a low refractive index,
The resin forming the core is a cured product of a first curable resin liquid that can be photocured at a certain wavelength,
The resin that forms the cladding is mainly a cured product of a second curable resin liquid having a composition different from that of the first curable resin liquid.
A self-forming optical waveguide, wherein a difference between a specific gravity of the first curable resin liquid and a specific gravity of the second curable resin liquid is 0.14 or more. 3. The self-forming optical waveguide according to claim 1, wherein the core has a branching portion or a bent portion at a joint portion with a total reflection mirror, a half mirror, or a dichroic mirror. 4. The self-forming optical waveguide according to claim 1, wherein the second curable resin liquid is a photocurable resin. 5. A method for producing a self-forming optical waveguide, wherein at least a part of a core is covered with a low refractive index cladding.
Adding a first curable resin liquid photocurable at a wavelength in a desired container;
Irradiating light to the first curable resin liquid and photocuring, forming at least a part of a columnar core; and
After forming the core of a desired shape, taking out most of the uncured first curable resin liquid out of the container;
A container having a core, which is a cured product of the first curable resin liquid, has at least a composition different from that of the first curable resin liquid and is compatible with the first curable resin. Filling the resin liquid and dissolving the uncured first curable resin liquid remaining in the container in the second curable resin liquid;
A step of curing the uncured first curable resin liquid and the second curable resin liquid,
Both the first curable resin liquid and the second curable resin liquid have a viscosity of 1500 mPa ^· s or less,
A method for producing a self-forming optical waveguide, wherein a difference between a solubility parameter of the first curable resin liquid and a solubility parameter of the second curable resin liquid is 4.4 MPa1 ^{/ 2} or less. A method for producing a self-forming optical waveguide, wherein at least a part of a core is covered with a low refractive index cladding.
Adding a first curable resin liquid photocurable at a wavelength in a desired container;
Irradiating light to the first curable resin liquid and photocuring, forming at least a part of a columnar core; and
After forming a core of a desired shape, removing the core and incorporating it in another container;
A container incorporating the core is filled with a second curable resin liquid having at least a composition different from that of the first curable resin liquid and having compatibility with the first curable resin, and the core surface, etc. Dissolving the uncured first curable resin liquid remaining in the second curable resin liquid;
A step of curing the uncured first curable resin liquid and the second curable resin liquid,
Both the first curable resin liquid and the second curable resin liquid have a viscosity of 1500 mPa · s or less,
A method for producing a self-forming optical waveguide, wherein a difference between a solubility parameter of the first curable resin liquid and a solubility parameter of the second curable resin liquid is 4.4 MPa1 ^{/ 2} or less. A method for producing a self-forming optical waveguide, wherein at least a part of a core is covered with a low refractive index cladding.
Adding a first curable resin liquid photocurable at a wavelength in a desired container;
Irradiating light to the first curable resin liquid and photocuring, forming at least a part of a columnar core; and
After forming the core of a desired shape, taking out most of the uncured first curable resin liquid out of the container;
A container having a core, which is a cured product of the first curable resin liquid, is filled with a second curable resin liquid having a composition different from that of the first curable resin liquid, and remains in the container. Moving the first curable resin liquid for curing to the upper or lower side of the container with the second curable resin liquid; and
A step of curing the uncured first curable resin liquid and the second curable resin liquid,
A method for producing a self-forming optical waveguide, wherein a difference between a specific gravity of the first curable resin liquid and a specific gravity of the second curable resin liquid is 0.14 or more. A method for producing a self-forming optical waveguide, wherein at least a part of a core is covered with a low refractive index cladding.
Adding a first curable resin liquid photocurable at a wavelength in a desired container;
Irradiating light to the first curable resin liquid and photocuring, forming at least a part of a columnar core; and
After forming a core of a desired shape, removing the core and incorporating it in another container;
The container incorporating the core is filled with a second curable resin liquid having a composition different from that of the first curable resin liquid, and the uncured first curable resin liquid remaining in the container is filled. Moving the container upward or downward with the second curable resin liquid;
A step of curing the uncured first curable resin liquid and the second curable resin liquid,
A method for producing a self-forming optical waveguide, wherein a difference between a specific gravity of the first curable resin liquid and a specific gravity of the second curable resin liquid is 0.14 or more. In the container, at least one of a total reflection mirror, a half mirror, or a dichroic mirror is disposed,
6. In the step of forming the columnar core, a junction between the total reflection mirror, half mirror, or dichroic mirror and the core is formed, and a branch of the core or a bent portion of the core is formed. Or the manufacturing method of the self-forming optical waveguide of Claim 7. In the container for forming the core, at least one of a total reflection mirror, a half mirror, or a dichroic mirror is disposed,
In the step of forming the columnar core, forming the junction between the total reflection mirror, half mirror, or dichroic mirror and the core and forming a branch of the core or a bent portion of the core,
In the step of taking out the core and incorporating it into another container, the core is taken out as a unit with the total reflection mirror, half mirror, or dichroic mirror and a branch of the core or a bent portion of the core, and incorporated into another container. A method for producing a self-forming optical waveguide according to claim 6 or 8. The method for producing a self-forming optical waveguide according to any one of claims 5 to 10, wherein the second curable resin liquid is a photocurable resin.

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