TWI533042B - Manufacturing method of optical part, and optical part, transparent part for formation of optical part, optical waveguide , optical module and transparent member for forming optical waveguide core pattern - Google Patents

Description

Method for producing optical member, optical member, transparent member for forming optical member, optical waveguide, optical module, and transparent member for forming optical waveguide core pattern

The present invention relates to a method for producing an optical member, an optical member, a transparent member for forming an optical member, an optical waveguide, and an optical module.

The antireflection member can be used in various applications, and is particularly used by attaching a film-shaped antireflection member to an element body or a member such as a display. In general, the antireflection function can form an antireflection film by forming a multilayer structure including the repeating structures by a high refractive index portion and a low refractive index portion containing a transparent material such as a metal oxide on a transparent substrate. These multilayer structures can be generally formed by a dry film formation method such as a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method. Among the above methods, there is an advantage that the film thickness of the low refractive index portion and the high refractive index portion can be precisely controlled.

Moreover, as the capacity of information increases, not only trunks (trunks) In the communication field such as line) or access system, the development of light interconnection technology using optical signals is also performed in information processing in a router or a server. Specifically, in order to use light for short-distance signal transmission between routers or boards in a server device or in a board, development of a photovoltaic composite substrate in which an optical transmission line is combined on an electric wiring board has been developed. As the optical transmission line, it is preferable to use an optical waveguide having a high degree of freedom in wiring and a high density compared with an optical fiber. Among them, an optical waveguide using a polymer material excellent in workability or economy is promising.

In the optical waveguide, for example, Patent Document 1 discloses that after forming a lower cladding layer on a carrier film, a resin for forming a core pattern is formed on the lower cladding layer, and a patterned core is formed by exposure and etching. A pattern and an optical waveguide with an upper cladding layer laminated.

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-195081

However, when the anti-reflection member is formed by the above-described dry film formation method, film formation must be performed in a vacuum, and thus there is a problem that productivity is low, and if it is exposed to a vacuum, damage to the transparent member may occur, or In the case where the film shape is curved (also included in the case of bending in manufacturing), or in a complicated case, or a transparent member having an intricate shape, there is a non-uniformity in the position at which the refractive index is generated.

Further, a core pattern is formed by etching as described in Patent Document 1. In the case of the optical waveguide of the case, the optical loss of the propagated core pattern is deteriorated due to the interface roughness between the cladding-core patterns or the inhomogeneity of the refractive index in the core pattern due to the etching liquid. Hey.

The present invention has been made to solve the above problems, and an object of the invention is to provide a method for producing an optical member which is excellent in mass productivity and capable of controlling the refractive index of a vicinity of a surface layer portion and a center portion of a transparent member with high precision in position; An optical waveguide having low optical loss is provided by being used in a core pattern of an optical waveguide including a lower cladding layer, a core pattern, and an upper cladding layer.

The inventors of the present invention have made an effort to solve the above problems, and as a result, have found that the above-described problem can be solved by making the transparent member used characteristic, and an example thereof is a method for producing an optical member having the following step A: The transparent member is exposed to the solution such that the refractive index of the exposed portion of the transparent member is substantially lower than the refractive index of the central portion of the transparent member that is not the exposed portion of the transparent member; The optical waveguide exhibits the optical member forming transparent member having such a feature as a core pattern forming member. The present invention has been completed based on this finding.

That is, the present invention relates to the following items.

(1) A method of producing an optical member, comprising the step A: exposing the transparent member to a solution such that a refractive index of a surface portion of the transparent member exposed to the solution is substantially lower than that not exposed to the The refractive index of the central portion of the transparent member in the solution.

(2) The method of producing an optical member according to (1) above, wherein In the step A, when the transparent member is exposed to the solution, the solution is impregnated into the transparent member.

(3) The method of producing an optical member according to the above (1), wherein the solution contains a refractive index controlling agent, and the refractive index controlling agent is expressed by being contained on a surface layer of the transparent member The function of substantially reducing the refractive index of the surface layer portion.

(4) A method for producing an optical member, comprising the step A' of: in a transparent member, a surface layer portion of the transparent member is provided with a refractive index controlling agent that substantially reduces a refractive index of the transparent member, thereby containing The refractive index of the surface layer portion of the refractive index controlling agent is substantially lower than the refractive index of the central portion of the transparent member not including the refractive index controlling agent.

(5) The method of producing an optical member according to any one of the above-mentioned, wherein the transparent member is a transparent member etchable by an etching solution, and the optical member is manufactured The method comprises a step B of patterning by etching, which step B can be carried out simultaneously with said step A or said step A', or before said step A or said step A'.

(6) The method of producing an optical member according to any one of the above aspects, wherein the transparent member is a transparent resin, and the refractive index controlling agent is a monovalent cation.

(7) The method of producing an optical member according to (6), wherein the solution is an alkali solution.

(8) The method of producing an optical member according to the above (6) or (7), wherein The monovalent cation is at least one of a potassium ion and a sodium ion.

(9) The method of producing an optical member according to any one of the above-mentioned, wherein the transparent resin is a photosensitive transparent resin, before the step A or the step A', Or / and before the step B, the step C: irradiating the actinic ray which can photoharden the photosensitive transparent resin.

(10) The method for producing an optical member according to any one of the above-mentioned (6), wherein, after the step A or the step A', the step D' is included: performing the transparent resin Heat hardened.

(11) A method of producing an optical member, comprising the step of: thermally curing a transparent resin such that a refractive index in the vicinity of a surface portion of the transparent resin is substantially lower than a refractive index in a central portion of the transparent resin.

The method for producing an optical member according to the above aspect, wherein the transparent resin contains at least (A) a matrix resin having a thermally polymerizable functional group, and (B) a thermally polymerizable compound.

(13) A transparent member for forming an optical member, which is used in the method for producing an optical member according to any one of the above (1) to (12).

(14) An optical member obtained by the method for producing an optical member according to any one of the above (1) to (12).

(15) An optical waveguide comprising an optical waveguide including a core portion and a cladding portion, wherein at least a portion of the periphery of the core pattern includes a central portion of the core pattern in a core pattern forming the core portion The surface portion of the low refractive index.

(16) An optical waveguide, wherein the optical waveguide according to (15) above is laminated The optical waveguide of the cladding layer, the core pattern, and the upper cladding layer includes a lower cladding layer or/and an upper cladding layer on the outer side of the surface layer portion having a low refractive index.

(17) The optical waveguide according to the above (15) or (16), wherein the core pattern having two or more sides is a core pattern including at least two sides of the two side walls.

(18) The optical waveguide according to (16) or (17) above, wherein the low refractive index portion is different from a refractive index difference between a center of the core pattern and a low refractive index portion around the core pattern The difference in refractive index between the lower cladding layer and/or the upper cladding layer is greater.

(19) The optical waveguide according to any one of the above (15), wherein the core pattern is a transparent member for forming an optical member according to (13) above. form.

(20) The optical waveguide according to any one of the above (15), wherein the surface layer portion includes a refractive index controlling agent for lowering the refractive index.

(21) An optical module using the optical waveguide according to any one of (15) to (20) above.

(22) A transparent member for forming an optical waveguide core pattern, which is a transparent member for forming a core pattern in an optical waveguide in which a lower cladding layer, a core pattern, and an upper cladding layer are laminated, when the core pattern is formed The periphery of the two sides or more may substantially form a surface layer portion having a refractive index lower than a central portion of the core pattern.

The method for producing an optical member of the present invention is excellent in mass productivity and can be placed in position The refractive index of the vicinity of the surface layer portion of the core pattern of the transparent member and the central portion is controlled with high precision, and therefore, it is a method for manufacturing an optical member suitable for the optical waveguide. Moreover, the optical waveguide of the present invention has low light propagation loss due to the use of a specific core pattern.

1‧‧‧Substrate

2‧‧‧Lower coating

3‧‧‧ core pattern

4‧‧‧ core pattern center

5‧‧‧Low refractive index

6‧‧‧Upper cladding

1(a) and 1(b) are cross-sectional views of an optical waveguide of the present invention.

One of the manufacturing methods of the optical member of the present invention comprises the step A, that is, exposing the transparent member to the solution, so that the refractive index of the exposed portion exposed by the transparent member is substantially lower than the central portion of the transparent member which is not the exposed portion of the transparent member. Refractive index. Thereby, a transparent member having a portion having a different refractive index can be formed, and thus it can be used in an anti-reflection member or a core pattern of an optical waveguide to be described later. The term "transparent" in the present invention means transparency with respect to the wavelength of light used in the optical member of the present invention, and may have transparency to the extent that it does not adversely affect the propagation of light. Further, the term "substantially lowering the refractive index" in the present invention means not only the exposure of the transparent member to the solution, but also the low refractive index of the portion exposed to the solution, and means that it is passed through The step of producing a refractive index difference eventually makes the refractive index relatively low. The step of generating the refractive index difference may be shortly after the step A, and may be followed by the step B of patterning or the step D of thermal hardening described later.

In the present invention, since the refractive index is substantially lowered by using a solution, there is an advantage that the refractive index of the exposed portion of the optical member can be controlled under uniform conditions. Moreover, in order to lower the refractive index of the exposed surface, for example, to form a transparent component After the layer is placed on the object, the refractive index difference between the object and the opposite surface can be lowered by performing step A.

The type of the transparent member is not particularly limited, and may be any material that can cause a difference in refractive index. As a method of producing a refractive index difference of the transparent resin using a solution, for example, there is a method in which (a) a portion where a density is small at an exposed portion of a transparent member using a solution, thereby producing a refractive index difference; (b) a transparent a method comprising: a high refractive index component soluble in a solution, a solution of the high refractive index soluble component dissolved by the solution to produce a refractive index difference; (c) exposing the solution containing the component having a lower refractive index than the transparent member, A method of immersing in the transparent member to fix a low refractive index component as a refractive index controlling agent in a transparent member to generate a refractive index difference. In addition, as described later, (d) exposure, impregnation may change the molecular structure, molecular network form of the refractive index control agent, between the exposed, impregnated and other parts A method of refractive index difference, and the like. By the method of (d), the molecular structure and the molecular network form can be changed by the subsequent process. Any of the above methods for producing a refractive index difference may be used. In the present invention, it is important that the refractive index of the exposed and impregnated portions is substantially lowered by the solution.

Further, if the obtained optical member is transparent and does not cause diffusion or scattering of the transmitted light, for example, if the transparent member does not inherently have an absorption band for the light used (the transmittance is lowered) The factor) or the void (a factor of diffusion or scattering) is preferable because transparency, haze, and the like are good. In particular, if there is a void, the refractive index control around the void becomes difficult, and therefore it is preferably not inherent.

In the step A, if the transparent member is impregnated, the solution having a substantially reduced refractive index can be used. The impregnation means that the penetration is in any depth direction, and the refractive index modulation in the depth direction can be performed by appropriately adjusting the concentration, amount, time, temperature, pressure, and the like of the exposed solution. In the method for producing an optical member according to the present invention, the refractive index from the surface of the optical member toward the center portion (exposed direction) is generally formed in a gradual manner, but the refractive index may be uniformly changed until a certain depth. . In particular, when the transparent member to be described later is a resin, the penetration depth due to the exposure of the solution and the amount of penetration of the solution tend to be inversely proportional, and thus it is easy to become the former. In the present invention, the "solution which can substantially reduce the refractive index" is not used in the production of a refractive index distribution type optical component or the like, and is liquid at room temperature and is in the vicinity of the surface layer portion of the transparent member. The remaining liquid contains only the liquid of the low refractive index monomer group. In the present invention, it means that water or an organic solvent as a solvent or a mixture of these or the like does not remain in the vicinity of the surface layer portion of the transparent member even after the subsequent step, or other components are mixed therein (for example, A liquid of an alkali component, an acid component, an additive component for solution adjustment, or a refractive index controlling agent to be described later.

In the present invention, the solution containing water as a main component is used in the step A, thereby avoiding the adverse effect due to dissolution or swelling of the transparent member, and therefore having low refraction of the surface portion in a state where the shape of the transparent member can be sufficiently maintained. The advantages of rate. Further, the pattern shape can be obtained with high precision by processing the pattern shape formed in the step B of patterning described later by the aqueous solution.

In the present invention, the refractive index of any portion can be adjusted by virtue of the fact that a refractive index controlling agent is contained in one of the transparent members. The present invention is in the form of the following functions The surface has a feature that the refractive index of the surface layer portion is substantially lowered by including the refractive index controlling agent in a surface portion of the transparent member. Further, from the viewpoints of transparency and haze, the refractive index controlling agent is preferably one which does not have an absorption band for light to be used (a factor of a decrease in transmittance) or a void (a factor of diffusion or scattering).

The refractive index controlling agent having an effect of substantially reducing the refractive index of the transparent member may be contained in the solution. Since the refractive index controlling agent is contained in advance, the refractive index controlling agent is simultaneously exposed and impregnated into the transparent member by exposure or impregnation of the solution, and it is easy to efficiently form a portion where the refractive index is relatively low.

The method for producing another optical member according to the present invention includes the step A', that is, in the transparent member, the surface layer portion of the transparent member contains a refractive index controlling agent which substantially reduces the refractive index of the transparent member, thereby allowing the refractive index control to be contained. The refractive index of the surface portion of the agent is substantially lower than the refractive index of the central portion of the transparent member containing no refractive index controlling agent. The step A' includes a method of preparing a transparent member at a stage where the surface layer of the transparent member is previously contained with a refractive index controlling agent, and a method of exposing or impregnating the transparent member to a solution and containing the refractive index controlling agent on the surface layer thereof. Both. In the latter case, for example, it may be subjected to a post-curing process such as thermal hardening, and as a result, the refractive index of the surface layer portion is relatively lowered.

Thereby, a transparent member having a portion having a different refractive index can be formed in the same manner as in the above-described step A. Therefore, it can be used in an anti-reflection film member or a core pattern of an optical waveguide to be described later.

The transparent member is a transparent member that can be etched by an etching solution, if included The step B of patterning by etching can process the transparent member into an arbitrary shape. Further, by performing the above step A or step A' simultaneously with the step B of patterning the transparent member or after the step B, the refractive index in the vicinity of the surface layer portion of the sidewall of the patterned transparent member can be lowered. Further, in the case of an etchable transparent member, a plurality of transparent members can be collectively formed, and the productivity is excellent.

The type of the transparent member is not particularly limited as long as it can be substantially reduced in refractive index by exposure of a solution or a refractive index controlling agent. If the transparent member is a transparent resin, it is easy to process from the viewpoint of easy processing. Preferably, if the refractive index controlling agent is a cation, it is easily exposed and impregnated, and if the solution exposed to the transparent member is an alkali solution, the handleability is better, and if the combination is the above, the above-described production method is easily exhibited. The effect is therefore preferred.

In the above-described combination, in a transparent member containing a resin composition in which the cation functions as a refractive index controlling agent, a solution containing a cation is used as an alkali solution, and the cation is impregnated into the transparent member, whereby the cation can be easily and easily The optical member is efficiently manufactured. One of the specific resin compositions of the invention can be found, for example, as described later.

When the cation is a positively charged ion, it is easily exposed and impregnated into the transparent resin, and is easily fixed by ionic bonding or the like in the transparent resin, which is preferable. Further, when it is a monovalent cation, the density due to ionic bonding crosslinking in the transparent resin is suppressed from increasing, and it is easy to substantially reduce the refractive index. If it is a cation of two or more valences, there is a phenomenon that the density increases due to the ion crosslinking or the reaction product of the polyvalent cation, and thus it is difficult to perform a substantial low refractive index. Chemical. Among the monovalent cations, particularly potassium ions and/or sodium ions are preferable because they are easy to handle, and generally have a hygroscopic property lower than that of other alkali metal ions.

In the present invention, as the refractive index controlling agent having the same function as the cation, a monofunctional compound (monomer) or a compound having a polymerizable functional group having a hardening reaction slower than a central portion of the transparent member can be used ( monomer). The monofunctional compound (monomer) is adsorbed or impregnated on the surface layer of the transparent member, for example, by exposing the transparent member in a solution containing an organic solvent containing the monofunctional compound (monomer). By the subsequent photohardening or thermal hardening treatment, the crosslinking density of the surface layer portion of the transparent member is lowered, so that the refractive index is relatively lower than that of the unimpregnated portion. Similarly, when a compound (monomer) containing a polymerizable functional group having a slow central portion of the transparent member is used, the hardening is slowed at the surface layer portion of the transparent member to suppress the crosslinking reaction, so that it can be formed. A portion having a relatively low refractive index as compared with the central portion of the transparent member.

Examples of the monofunctional compound (monomer) include an acrylate or a methacrylate having a compound having one ethylenically unsaturated bond in one molecule, or an epoxy compound having one epoxy group. The transparent member used in the present invention contains at least a polyfunctional acrylate having two or more ethylenically unsaturated bonds, as a compound (monomer) containing a slow polymerizable functional group at a central portion of the relatively transparent member. In the case of methacrylate or the like, a compound having only one group selected from the group of the following groups, or the like: an addition polymerization aryl group which is slower than the ethylenically unsaturated bond, an epoxy group, and an amine formation can be used. Isocyanate group of a urethane bond. Further, when these compounds are materials having a low refractive index, the effect of substantially lowering the refractive index when used as a refractive index controlling agent is further increased. Examples of the compound having such a function include a monofunctional compound (monomer) containing no aromatic ring or alicyclic ring, or a compound (monomer) containing a polymerizable functional group having a slow curing reaction. In addition to this, a compound containing a fluorine element can also be used.

When the transparent member is a transparent resin, the transparent resin is more preferably a photosensitive transparent resin. Further, it is preferable to include the step C of irradiating the photosensitive transparent resin with an actinic ray which can be photocured before the step A or the step A' or before the step B'. Thereby, even if the transparent resin is exposed to a solution (an aqueous solution, an alkali solution or an organic solvent), it can be photohardened by actinic rays to improve the solution resistance. Further, the etching resistance to the etching liquid is improved when patterning by etching. When the solution and the etching liquid are the same liquid (may be a mixed liquid), the steps A and B can be simultaneously performed, and workability and mass productivity are improved.

In another method for producing an optical member according to the present invention, when the transparent member is a transparent resin and the transparent member can be cured by heat, the step D is included, that is, the transparent resin is heat-hardened to be thermally cured. The refractive index in the vicinity of the surface portion of the transparent resin is substantially lower than the refractive index in the central portion of the transparent resin after the heat curing. As a material of the transparent resin to be used at this time, a transparent resin which can be thermally cured to have a refractive index in the vicinity of the surface layer portion after curing which is lower than the refractive index of the central portion can be selected. The difference in refractive index can be produced by suppressing thermal hardening of the surface layer of the transparent resin (for example, a function of hardening by oxygen), or by subjecting the refractive index controlling agent to a prior exposure and impregnation to the surface layer of the transparent resin. In the former case At the time of thermal hardening of the transparent resin, the hardening in the vicinity of the surface layer portion of the transparent resin can be suppressed only by adjusting the surrounding gas atmosphere, so that the refractive index in the vicinity of the surface layer portion becomes lower than the refractive index at the center portion. In the latter case, if a crosslinking reaction agent is used to suppress the crosslinking reaction, the refractive index controlling agent can make the network structure crosslinked by heat become looser than the center portion. In the present invention, the change of the cross-linking structure or the suppression of the cross-linking reaction is set to the hardening suppression in a broad sense, and if the refractive index difference is generated by the hardening suppression, not only the refractive index is easily controlled but also the position is high. The refractive index control is performed with precision, so the latter method is preferred. The material composition which can exhibit such a phenomenon is as described later.

When the refractive index difference is generated by thermal hardening, even in such a member which is heated in the subsequent step, the refractive index difference can be stably maintained. Further, in the case where the refractive index difference is generated before the step D, the same as the former, even in such a member which is reheated in the step after the heating step (step D), the refractive index difference can be stably maintained. Further, when the refractive index difference is generated by thermal hardening, it is easy to ensure a difference in refractive index, which is more preferable. From the above viewpoints, it is more preferable if it is a material composition which causes a change in the aforementioned network structure by the difference in refractive index.

As the step D', the step of thermally hardening the transparent resin may be included after the step A or the step A'. When the thermal curing is performed, the unreacted photohardening component and the thermosetting component can be hardened by heat, and the exposed and impregnated refractive index reducing agent can be fixed to some extent. Step D' may also be step D above.

The transparent resin used as an example of the transparent member of the present invention contains at least (A) a matrix resin having a thermally polymerizable functional group, and (B) a thermal polymerizable property. The transparent resin of the compound can be used. In this case, as the refractive index controlling agent, for example, a refractive index difference can be produced by exposure or impregnation of a substance which inhibits the crosslinking reaction of (A) and (B). Particularly preferred is (A) a carboxyl group in the molecule, (B) an epoxy group which is thermally crosslinked with the carboxyl group in the molecule, and a refractive index controlling agent which is a substance which inhibits crosslinking reaction between the carboxyl group and the epoxy group. . More specifically, by using the above cation as the carboxyl group and the carboxyl group salt, the crosslinking reaction between the carboxyl group and the epoxy group can be suppressed. By suppressing the crosslinking reaction, the exposed and impregnated surface layer portion becomes a two-component system of the crosslinked body of (A) and (B), and the center portion which is not inhibited by the crosslinking reaction becomes (A) and (B). ) Cross-linked into one component. The difference in the number of these component systems affects the material density, and generally the tendency to decrease the density of the component system increases. Therefore, the refractive index of the center portion becomes high, and the refractive index of the surface layer becomes low. Further, in general, when a cation plasma is contained, the polarization tends to increase, and the refractive index rises (the relationship between the refractive index and the material density and the polarization generally has a linear relationship), and the above-mentioned crosslinking density is dominantly helpful. The resin composition having a refractive index lowers the refractive index even if it contains a cationic plasma. This effect becomes remarkable when a monovalent cation is used as a cation.

Further, when the refractive index difference is generated by thermal hardening by the step D, the refractive index after the thermosetting (corresponding to the refractive index of the central portion) is higher than that after the exposure (before the thermal curing) More preferably, the resin of 0.003 or more, more preferably a resin having a height of 0.005 or more, and still more preferably a resin having a height of 0.008 or more, is preferable because the hardening by heat is inhibited from affecting the refractive index.

Next, an optical waveguide which is preferable as a specific example of the optical member To be detailed.

The optical waveguide of the present invention is shown in Fig. 1 (a) and Fig. 1 (b). Fig. 1(a) is a view schematically showing a cross-sectional view of an optical waveguide, and Fig. 1(b) is a photograph showing a cross-sectional view (a portion surrounded by a broken line) of a core portion formed on the optical waveguide. The optical waveguide of the present invention is an optical waveguide including a lower cladding layer 2, a core pattern 3, and an upper cladding layer 6 which are formed on the substrate 1 as shown in Figs. 1(a) and 1(b), and a core pattern. Two or more of the circumferences of 3 (i.e., two or more of the four sides of the quadrilateral as the cross-sectional shape of the core pattern) have a low refractive index portion 5 having a refractive index lower than the central portion 4 of the core pattern, at a low refractive index The outer side of the portion 5 has a lower cladding layer 2 or/and an upper cladding layer 6 having a further lower refractive index.

In the present invention, the periphery of the core pattern 3 means a peripheral portion of the "inner" of the core pattern 3. By having at least two sides or more having a lower refractive index portion 5 having a lower refractive index than the central portion 4 of the core pattern, light propagating through the core pattern is easily propagated through the core pattern center portion 4, and optical loss can be reduced. In addition, by disposing the lower cladding layer 2 or the upper cladding layer 6 having a lower refractive index on the outer side of the low refractive index portion 5, the light propagating through the core pattern 3 should be leaked to the low refractive index portion 5 The outer components are efficiently confined within the core pattern 3. In the case of such an optical waveguide, for example, light that has propagated through the linear core pattern 3 easily propagates through the core pattern center portion 4, and light loss is low, and the core pattern 3 should be leaked to the outside of the core pattern 3 due to bending or the like. The light is totally reflected at the interface between the cladding layer 2 or the upper cladding layer 6 and the core pattern 3 at a lower refractive index difference, and thus it becomes difficult to generate light loss.

According to the above, it is preferable that the two sides are the two sides of the core pattern 3 When the wall is three or more, the above effects are performed on three or more sides, so that lower light loss can be achieved, which is more preferable.

Further, the low refractive index portion 5 and the lower cladding layer 2 and/or the upper portion are compared with the refractive index difference represented by the following formula in the low refractive index portion 5 around the central portion 4 of the core pattern and the core pattern. When the difference in refractive index of the coating layer 6 is larger, the light component which should be leaked from the low refractive index portion 5 can be more effectively confined in the core pattern 3, which is preferable.

[Formula 1] (refractive index difference) = (n ₁ ^{2 -} n ₂ ² ) ^1/2 / (2 × n ₁ ² )

Here, n ₁ and n ₂ are the refractive index of the high refractive index portion and the refractive index of the low refractive index portion, respectively.

The method for forming the core pattern of the optical waveguide is not particularly limited, and can be formed by the above-described optical member and optical member manufacturing method of the present invention. In particular, if the solution is made of the same liquid as the etching liquid, the core pattern having substantially the refractive index difference described above can be formed while forming the core pattern by etching.

When the core pattern is formed by the transparent member for forming a core pattern used in the formation, the peripheral surface layer of two or more sides can substantially form a low refractive index portion having a refractive index lower than the center of the core pattern, and for example, the above-mentioned At least (A) a matrix resin having a thermopolymerizable functional group, (B) a dry film of a transparent polymer of a thermally polymerizable compound, or the like.

1(a) and 1(b) are diagrams showing an example of a representative optical waveguide of the present invention, but the optical waveguide of the present invention is not limited to only shown in Figs. 1(a) and 1(b). An example of the shape of the film. For example, it can also be applied to a general optical fiber-shaped optical waveguide including a core portion and a cladding portion, and can be set in a core pattern forming the core portion, and at least one portion of the core pattern includes a ratio An optical waveguide of a surface portion having a low refractive index at a central portion of the core pattern. Further, in the optical waveguide shown in FIGS. 1(a) and 1(b), a film-shaped optical waveguide having no lower cladding layer 2 may be used. In this case, the substrate 1 also serves as a lower cladding layer, and the substrate 1 can use not only a hard substrate such as a ruthenium substrate, a glass substrate or a glass epoxy substrate, but also a film substrate.

The optical waveguide of the present invention can be used as an optical module optically coupled to an optical fiber or a light-emitting element or a light-receiving element.

Hereinafter, each member and material used in the present invention will be described in detail.

[transparent member]

The type of the transparent member used in the present invention is a material which is substantially reduced in refractive index in the vicinity of the surface layer portion of the transparent member, and has a range which does not adversely affect the wavelength of light used. The transparency is sufficient, and it may be quartz, glass, resin, or the like. From the viewpoint of the modulation of the refractive index and the easiness of control, a transparent resin is preferred. Further, since the refractive index of the central portion of the transparent member is the refractive index of the member itself, it is easy to maintain the stability and permeability of the refractive index, which is preferable.

[Transparent resin]

The transparent resin used in the present invention is not limited as long as it is a transparent resin having the properties of the above transparent member. The transparent resin which is an example of the transparent member of the present invention may be a transparent resin containing at least (A) a matrix resin having a thermopolymerizable functional group and (B) a thermally polymerizable compound. The refractive index difference can be produced by exposure, impregnation, and a substance containing a crosslinking reaction that inhibits (A) and (B). In particular, when (A) has a carboxyl group in the molecule and (B) has an epoxy group or the like which is thermally crosslinked with the carboxyl group in the molecule, the crosslinking reaction between the carboxyl group and the epoxy group can be suppressed, specifically The cation is preferably a carboxyl group and a carboxylate, and is capable of inhibiting a crosslinking reaction between a carboxyl group and an epoxy group. By suppressing the crosslinking reaction, the exposed, impregnated, and contained surface layer portion is a two-component system of the crosslinked body of (A) and (B), and the center portion which is not inhibited by the crosslinking reaction is (A) and (B) One component system which is crosslinked. The difference in the number of these component systems affects the material density, and generally the tendency to decrease the density of the component system increases. Therefore, the refractive index of the center portion becomes high, and the refractive index of the surface layer becomes low. Further, in general, when a cation plasma is contained, the polarization tends to increase, and the refractive index rises (the relationship between the refractive index and the material density and the polarization generally has a linear relationship), and the above-mentioned crosslinking density is dominantly helpful. The resin composition having a refractive index lowers the refractive index even if it contains a cationic plasma. The mechanism for producing a refractive index difference of a transparent resin according to an example of the present invention will be described in detail as described above, and an important aspect is that a refractive index difference is generated, and the refractive index in the vicinity of the surface layer portion becomes smaller than the refractive index of the central portion.

Further, it is preferable that the transparent resin contains (C) a photopolymerizable compound and further contains (D) a photopolymerization initiator. By containing (C) or (D), Photohardening can be carried out by exposure of step C, and can impart resistance to a solution or an etchant. Further, it is easy to process into an arbitrary shape by the etching step of the step B. Further, when (C) is contained and (C) is not crosslinked with (A) or (B), the number of the above-mentioned component systems is a three-component system in the vicinity of the surface layer portion, and the center portion is a two-component system. The refractive index difference is generated in the same manner as described above.

Hereinafter, the compounds (A) to (D) will be described in detail.

The (A) component is, for example, a matrix resin (polymer) having a thermopolymerizable functional group, and a carboxyl group-containing polymer is preferred. The polymer is not particularly limited, and examples thereof include the polymers represented by the following (1) to (6).

(1) A carboxyl-containing alkali-soluble polymer obtained by copolymerizing a compound having a carboxyl group and an ethylenically unsaturated group in a molecule with a compound having an ethylenically unsaturated group.

(2) a carboxyl group-containing group obtained by partially introducing an ethylenically unsaturated group into a side chain of a copolymer having a carboxyl group and an ethylenically unsaturated group in a molecule and a compound having an ethylenically unsaturated group Alkali soluble polymer.

(3) a copolymer having a compound having an epoxy group and an ethylenically unsaturated group in the molecule and a compound having an ethylenically unsaturated group, and a compound having a carboxyl group and an ethylenically unsaturated group in the molecule The reaction is carried out, and the resulting hydroxyl group is reacted with a polybasic acid anhydride to obtain a carboxyl group-containing alkali-soluble polymer.

(4) a copolymer obtained by reacting an acid anhydride having an ethylenically unsaturated group with a compound having an ethylenically unsaturated group, and a compound having a hydroxyl group and an ethylenically unsaturated group in the molecule, and having a carboxyl group Alkali soluble polymer.

(5) An alkali-soluble polymer containing a carboxyl group obtained by reacting a bifunctional epoxy resin with an addition polymer of a dicarboxylic acid or a bifunctional phenol compound with a polybasic acid anhydride.

(6) An alkali-soluble polymer containing a carboxyl group obtained by reacting a hydroxyl group of a difunctional propylene oxide compound with an addition polymer of a dicarboxylic acid or a bifunctional phenol compound with a polybasic acid anhydride.

From the viewpoints of the solubility in the alkali solution in the case where the alkali solution is used in the etching solution, the alkali-soluble polymer having a carboxyl group represented by the above (1) to (4) is preferred. . Further, the polymer is preferably a (meth)acrylic acid polymer having a (meth)acrylonitrile group. Here, the (meth)acryl fluorenyl group means an acryl fluorenyl group and/or a methacryl fluorenyl group, and the so-called (meth)acrylic acid polymer means acrylic acid, acrylate, methacrylic acid, methacrylic acid ester, And the derivatives are monomers which are polymerized by polymerization. The (meth)acrylic polymer may be a homopolymer of the above monomers, or may be a copolymer obtained by polymerizing two or more of these monomers. In addition, a copolymer of the above monomer other than the above-mentioned monomer and, if necessary, an ethylenically unsaturated group other than the (meth) acrylonitrile group may be contained in the range which does not inhibit the effect of this invention. Further, it may be a mixture of a plurality of (meth)acrylic polymers.

The weight average molecular weight of the polymer of the component (A) is preferably from 1,000 to 3,000,000. When it is 1,000 or more, the molecular weight is large, so that the strength of the cured product when the resin composition is formed is sufficient; when it is 3,000,000 or less, the solubility with respect to the etching solution containing the alkali solution or (B) the polymerizable compound Good compatibility.

From the above point of view, the weight average molecular weight of the component (A) is better. 3,000~2,000,000, especially 5,000~1,000,000.

Further, the weight average molecular weight in the present invention is measured by gel permeation chromatography (GPC) and is converted to a value in terms of standard polystyrene.

In the case where an alkali-soluble polymer having a carboxyl group is used as the component (A), the acid value can be specified by etching in an alkali solution in the step of patterning by etching. For example, in the case of using an alkali solution described later, the acid value is preferably from 20 mgKOH/g to 300 mgKOH/g.

When it is 20 mgKOH/g or more, it is easy to etch, and if it is 300 mgKOH/g or less, the etching liquid resistance does not fall. From the above viewpoints, the acid value is more preferably from 30 mgKOH/g to 250 mgKOH/g, particularly preferably from 40 mgKOH/g to 200 mgKOH/g.

In addition, the etching resistance is a property in which a portion which is not patterned by etching and is not eroded by an etching liquid.

Further, when an alkaline semi-aqueous etching solution containing an alkaline aqueous solution and one or more organic solvents is used as the alkali solution, the acid value is preferably from 10 mgKOH/g to 260 mgKOH/g. When the acid value is 10 mgKOH/g or more, the development is easy. When the acid value is 260 mgKOH/g or less, the etching liquid resistance (the property in which the pattern is not etched by the etching liquid without being removed by etching) does not decrease. From the above viewpoints, the acid value is more preferably from 20 mgKOH/g to 250 mgKOH/g, particularly preferably from 30 mgKOH/g to 200 mgKOH/g.

The blending amount of the component (A) is preferably relative to the component (A) and (B) The total amount of the components is 10% by mass to 85% by mass. When the content is 10% by mass or more, the strength and flexibility of the cured product of the transparent resin are sufficient. When the content is 85% by mass or less, the component (B) is easily cured during the exposure, and the etching resistance is not improved. insufficient. From the above viewpoints, the blending amount of the component (A) is more preferably 20% by mass to 80% by mass, particularly preferably 25% by mass to 75% by mass.

The thermally polymerizable compound of the component (B) may be a compound which can be crosslinked by heat, and examples thereof include a compound having a thermally polymerizable substituent such as an epoxy group.

Specific examples thereof include a bifunctional phenol glycidyl ether type epoxy resin; a hydrogenated bifunctional phenol glycidyl ether type epoxy resin; a trifunctional or higher polyfunctional phenol glycidyl ether type epoxy resin; and a bifunctional aliphatic alcohol shrinkage Glycidyl ether type epoxy resin; 2-functional alicyclic alcohol glycidyl ether type epoxy resin; polyfunctional aliphatic alcohol glycidyl ether type epoxy resin having 3 or more functions; 2 functional aromatic glycidyl ester; 2 functional alicyclic ring Glycidyl ester; bifunctional aromatic glycidylamine; polyfunctional aromatic glycidylamine having more than 3 functional groups; 2-functional alicyclic epoxy resin; polyfunctional alicyclic epoxy resin having 3 or more functional groups; A polyfunctional heterocyclic epoxy resin; a bifunctional or trifunctional or higher polyfunctional epoxy resin containing fluorene.

These compounds may be used singly or in combination of two or more kinds thereof, or may be further used in combination with other polymerizable compounds.

The photopolymerizable compound as the component (C) may be a compound which can be crosslinked by light, and examples thereof include a compound having a photopolymerizable substituent such as an ethylenically unsaturated group.

Specific examples thereof include (meth) acrylate, vinylidene halide, vinyl ether, vinyl ester, vinyl pyridine, vinyl decylamine, aryl vinyl, and the like, and from the viewpoint of transparency, Preferred are (meth) acrylate or arylated vinyl. As the (meth) acrylate, any of a monofunctional group, a bifunctional group, or a polyfunctional group can also be used.

The monofunctional (meth) acrylate is not particularly limited, and examples thereof include various (meth)acrylic acid alkyl esters and various aliphatic (meth) acrylates such as hydroxyalkyl (meth) acrylates; and alicyclic rings; a (meth) acrylate; an aromatic (meth) acrylate; a heterocyclic (meth) acrylate; ethoxylates thereof; the propoxylates; ethoxylated Propoxylates; such caprolactone modifiers and the like.

The bifunctional (meth) acrylate is not particularly limited, and examples thereof include various aliphatic di(meth)acrylates such as ethylene glycol di(meth)acrylate; and cyclohexane dimethanol di(methyl). Various alicyclic di(meth)acrylates such as acrylate; various aromatic (meth)acrylates such as bisphenol A di(meth)acrylate; and various (meth)acrylates of isocyanuric acid Heterocyclic di(meth)acrylates; ethoxylates thereof; such propoxylates; ethoxylated propoxylates; caprolactone modifications; Various aliphatic epoxy di(meth)acrylates such as pentanediol type epoxy di(meth)acrylate; hydrogenated bisphenol A type epoxy (meth)acrylate and various alicyclic epoxy di(A) Base) acrylate; various aromatic epoxy di(meth)acrylates such as bisphenol A type epoxy di(meth)acrylate.

The trifunctional or higher polyfunctional (meth) acrylate is not particularly limited, and examples thereof include various aliphatics such as trimethylolpropane tri(meth)acrylate. Any of various heterocyclic (meth) acrylates such as tris (meth) acrylate such as isomeric isocyanate; ethoxylates thereof; and propoxylates thereof; a propoxylate; a caprolactone modified product; a phenolic novolac type epoxy (meth) acrylate, a cresol novolak type epoxy (meth) acrylate, and the like, various aromatic epoxy resins (Meth) acrylate, etc.

The monofunctional (meth) acrylate, the bifunctional (meth) acrylate, and the trifunctional or higher polyfunctional (meth) acrylate may be used alone or in combination of two or more. Further, a (meth) acrylate having a different number of functional groups may be used in combination. Further, it can also be used in combination with other polymerizable compounds.

As the photopolymerization initiator of the component (D), a photoradical polymerization initiator or a photocationic polymerization initiator or the like is used, in order to reduce the refractive index difference caused by the inhibition of thermal hardening, if the photohardening in the step B is reduced The number of crosslinks caused, or the increase in the refractive index due to photohardening. Thereby, the refractive index rising stroke of the transparent resin becomes a thermal curing step, and is easily affected by the refractive index which is inhibited by the crosslinking as described above, and the refractive index in the vicinity of the surface layer portion of the transparent resin is easily lowered. From the above viewpoints, it is preferred to use a photoradical hardener as compared with the photocationic hardener. Specific examples thereof include benzoin ketal; α-hydroxyketone; glyoxylate; α-amino ketone; phosphine oxide; 2,4,5-triarylimidazole dimer; benzophenone a compound; an anthraquinone compound; a benzoin compound; a benzyl compound; an acridine compound; N-phenylglycine, coumarin, and the like.

Moreover, in the 2,4,5-triarylimidazole dimer, the substituents of the aryl groups of the two triarylimidazole sites may be the same to provide a symmetric compound, or may be different An asymmetric compound is provided.

From the viewpoints of self-hardening property, transparency, and heat resistance, preferred are the above-mentioned α-hydroxyketones; the above-mentioned glyoxylic acid esters; and the above-mentioned phosphine oxides.

The above photoradical polymerization initiators may be used singly or in combination of two or more. Alternatively, it may be used in combination with a suitable sensitizer.

The component (B) and the component (C) used in the present invention are more preferably a mixed compound containing a photopolymerizable ethylenically unsaturated group and a thermally polymerizable epoxy group in one molecule. In the present invention, in this case, it is considered that the component (B) and the component (C) are contained in one component.

By containing the compound of the type, even if the three components (A), (B), and (C) are contained, the number of the component systems as described above after thermal curing as described above becomes a two-component system in the vicinity of the surface layer portion. The center portion is a one-component system, and a refractive index difference can be generated in the same manner as described above. Further, since the number of crosslinks of the ethylenically unsaturated group is small, the refractive index of the transparent resin is higher than the degree of increase in refractive index due to photohardening, and the degree of increase in refractive index due to thermal hardening. Thereby, if thermal hardening is suppressed, it becomes easy to generate a refractive index difference.

The mixed polymerizable compound is an epoxy (meth) acrylate obtained by reacting an epoxy resin having two or more glycidyl groups in a molecule with a (meth)acrylic compound, and is preferably relative to The epoxy group is reacted with 0.1 to 0.9 equivalents of a (meth)acrylic acid compound, more preferably 0.2 to 0.8 equivalents. Particularly preferred is 0.4 equivalents to 0.6 equivalents.

Specific examples include a bisphenol A type epoxy (meth) acrylate and the like. Phenol glycidyl ether; hydrogenated bisphenol A type epoxy (meth) acrylate, etc. derived from hydrogenated bifunctional phenol glycidyl ether, phenolic novolak type epoxy (meth) acrylate, etc. derived from polyfunctional phenol shrinkage Glyceryl ether; polyethylene glycol type epoxy (meth) acrylate derived from difunctional aliphatic alcohol glycidyl ether; cyclohexane dimethanol type epoxy (meth) acrylate derived from 2 functional lipid a cyclic alcohol glycidyl ether; a trimethylolpropane type epoxy (meth) acrylate derived from a polyfunctional aliphatic alcohol glycidyl ether; a phthalic acid diglycidyl ester derived from a bifunctional aromatic An example of a glycidyl ester; an epoxy (meth) acrylate derived from a bifunctional alicyclic glycidyl ester, etc., such as tetrahydrophthalic acid diglycidyl ester.

Preferred from the viewpoints of transparency, high refractive index, and heat resistance, bisphenol A type epoxy (meth) acrylate, bisphenol F type epoxy (meth) acrylate, bisphenol AF Epoxy (meth) acrylate, bisphenol AD epoxy (meth) acrylate, biphenyl epoxy (meth) acrylate, naphthalene epoxy (meth) acrylate, fluorene epoxy An epoxy (meth) acrylate such as a (meth) acrylate, a phenol novolak type epoxy (meth) acrylate or a cresol novolak type epoxy (meth) acrylate.

[near the surface layer]

In the optical member of the present invention, the exposed portion, the impregnated portion, and the portion containing the refractive index reducing agent of the transparent member are in the vicinity of the surface portion of the transparent member, by adjusting the amount of exposure, impregnation or time, or by The depth contained in any depth can be selected arbitrarily to form a layer whose refractive index is substantially reduced in any depth direction.

The depth (the thickness in the vicinity of the surface layer portion) is not limited, and may be 0.01 μm to 5 mm, and if it is 0.05 μm to 1 mm, the depth control becomes relatively easy. Therefore, it is more preferable that if it is 0.1 μm to 100 μm, the depth control becomes easier, and therefore it is further preferable. When it is used in the core pattern of the optical waveguide, if it is further 0.1 μm to 30 μm, low light loss can be achieved, which is preferable.

In the case where the solution is used to substantially lower the refractive index, all of the faces exposed to the solution have a lower refractive index in the above-described depth direction. In the case of the core pattern of the optical waveguide, a layer of low refractive index is formed on at least two sides and the upper surface.

[solution]

The solution used in the method for producing an optical member of the present invention is a solution in which the refractive index in the vicinity of the surface portion of the transparent member is substantially lower than the refractive index in the central portion of the transparent member after the solution is exposed in the transparent member. Just fine. By using the solution, the refractive index in the vicinity of the surface layer portion of the transparent member is substantially lowered, and the unevenness at the position where the refractive index is lowered can be suppressed, and even if the transparent member has a complicated shape or an intricate shape, the refractive index can be substantially reduce.

As the kind of the solution, water, an organic solvent, an alkali solution, an acidic solution or the like can be used. For example, in the case of using a method in which a portion having a small density is formed by a solution at a portion exposed to a transparent member as described above, thereby producing a difference in refractive index, a solution which can dissolve at least a part of the exposed portion can be used. Further, in the case where a component having a high refractive index and a solution soluble in a transparent member is used in a transparent member to dissolve a high refractive index soluble component to produce a refractive index difference, if it is used in particular, A solution which selectively dissolves a soluble component having a high refractive index may be used. Further, a solution containing a component having a refractive index lower than that of the transparent member is exposed and impregnated into the transparent member, and a low refractive index component is fixed in the transparent member to cause a refractive index difference. In the case of the method, a solution which can dissolve the low refractive index component and permeate it into the transparent resin can be used. When a method of producing a refractive index difference by exposing or impregnating a refractive index controlling agent which changes a molecular structure or a molecular network form as described later, if it is used, the refractive index controlling agent can be dissolved and infiltrated. The solution in the transparent resin can be used. When a solution containing water as a main component is used in the solution, adverse effects due to dissolution or swelling of the transparent member are avoided, so that the shape of the transparent member or the pattern formed on the transparent member can be maintained with high precision. The refractive index is controlled in the shape of the shape.

As the type of the organic solvent, an organic solvent which can achieve the above object can be selected, and examples thereof include toluene, xylene, mesitylene, cumene, p-cymene, and the like. Aromatic hydrocarbon; chain ether such as diethyl ether, tert-butyl methyl ether, cyclopentyl methyl ether, dibutyl ether; cyclic ether such as tetrahydrofuran or 1,4-dioxane; methanol, ethanol, isopropanol, An alcohol such as butanol, ethylene glycol or propylene glycol; a ketone such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone or 4-hydroxy-4-methyl-2-pentanone; methyl acetate, Ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, γ-butyrolactone, etc.; carbonate such as ethylene carbonate or propylene carbonate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol Polyol alkyl ethers such as monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether; ethylene glycol monomethyl ether acetate, Glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, Polyol alkyl ether acetate such as diethylene glycol monoethyl ether acetate; N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc. Amines, etc.

These organic solvents may be used singly or in combination of two or more.

As the type of the alkali solution, an alkali solution which can achieve the above-mentioned object can be selected, and a solution obtained by dissolving an alkali metal hydroxide such as lithium hydroxide, sodium hydroxide or potassium hydroxide can be mentioned. Alkali metal carbonate such as lithium carbonate, sodium carbonate or potassium carbonate; alkali metal hydrogencarbonate such as lithium hydrogencarbonate, sodium hydrogencarbonate or potassium hydrogencarbonate; alkali metal phosphate such as potassium phosphate or sodium phosphate; sodium pyrophosphate and pyrophosphoric acid Alkali metal pyrophosphate such as potassium; sodium salt such as sodium tetraborate or sodium metasilicate; ammonium salt such as ammonium carbonate or ammonium hydrogencarbonate; tetramethylammonium hydroxide, triethanolamine, ethylenediamine, diethylenetriamine, 2 a base such as an organic base such as amino-2-hydroxymethyl-1,3-propanediol or 1,3-diaminopropanol-2-morpholine.

These bases may be used singly or in combination of two or more.

As the type of the acidic solution, an acidic solution which can achieve the above object can be selected, and examples thereof include hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chlorous acid, chloric acid, and perchloric acid. Hypobromous acid, bromic acid, bromic acid, perbromic acid, hypoiodous acid, iodic acid, iodic acid, periodic acid, sulfuric acid, fluorosulfonic acid, nitric acid, phosphoric acid, hexafluoroantimonic acid, tetrafluorophosphoric acid, chromium Acid, boric acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, trifluoromethanesulfonic acid, formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, tartaric acid, ascorbic acid, Meldrum's acid, etc. A solution obtained by mixing two or more of these.

Further, in the above water, an organic solvent, an alkali solution, or an acidic solution, a refractive index reducing agent which can lower the refractive index of the transparent resin may be contained as needed.

[Refractive Index Control Agent]

In the present invention, the refractive index controlling agent which can substantially reduce the refractive index in the vicinity of the surface layer portion of the transparent member is not particularly limited as long as it can substantially reduce the refractive index, for example, the refractive index is lower than that of the transparent one. a resin, which is fixed to the surface of the transparent resin by exposure, impregnation, or inclusion, or a transparent member as a transparent resin as described later, and a substance having a function of suppressing the crosslinking reaction as a refractive index controlling agent It is exposed, impregnated, and contained on the surface of the transparent resin to reduce the refractive index. As described above, the present invention has a large feature in that the surface layer portion of the transparent member contains a refractive index controlling agent, and exhibits a function of substantially lowering the refractive index of the surface layer portion. In the case of the above-mentioned resin composition, if the refractive index controlling agent is a cation, the refractive index can be effectively lowered, so that it is preferable, and if it is a positive monovalent metal ion, ion crosslinking is suppressed. On the other hand, it is more preferable to fix it by using an ionic bond or the like, and it is more preferable, and it is more preferable if it is a potassium ion or a sodium ion. Therefore, the aforementioned alkali solution can be used as a refractive index controlling agent.

Further, in the present invention, a monofunctional compound (monomer) or a compound (monomer) containing a polymerizable functional group having a slower reaction than a central portion of the transparent member is used instead of the monovalent metal ion as a refractive index controlling agent. In the case of the same, the effect of suppressing the crosslinking reaction can be obtained, and the refractive index in the vicinity of the surface layer portion of the transparent member is substantially lowered.

[optical waveguide]

The optical waveguide of the present invention is an optical waveguide including a lower cladding layer, a core pattern, and an upper cladding layer, and two or more of the four sides of the four-sided shape of the cross-sectional shape of the core pattern The periphery includes a low refractive index portion having a refractive index lower than the center of the core pattern, and a lower cladding layer or/and an upper cladding layer having a lower refractive index on the outer side of the low refractive index portion. The above-mentioned two sides are preferably two side walls of the core pattern, more preferably three or more sides.

Further, it is preferable that the low refractive index portion and the lower cladding layer and/or the upper portion are compared with the refractive index difference (the value calculated by the above formula) of the low refractive index portion around the center of the core pattern and the core pattern. The difference in refractive index of the cladding layer becomes large. Thereby, the light component which should be leaked from the low refractive index portion can be more effectively confined in the core pattern.

It is preferable that the refractive index difference between the center of the core pattern and the low refractive index portion around the core pattern is 0.01% to 2.0% (the value of the equation is multiplied by 100), and from the viewpoint of the easiness of controlling the refractive index of the material, If it is 0.02% to 2.0%, it is more preferable, and if it is 0.03% to 1.0%, it is further preferable.

The difference in refractive index between the low refractive index portion and the lower cladding layer or/and the upper cladding layer is greater than the refractive index difference between the center of the core pattern and the low refractive index portion around the core pattern, and is 0.1% to 6.0%. Preferably, from the viewpoint of optical limitation and the easiness of refractive index control of the material, it is preferably 1.0% to 5.0%, and further preferably 2.0% to 5.0%.

Further, when the refractive index of the central portion 4 of the core pattern 3 is the refractive index of the cured resin for forming the core pattern, it is easy to maintain the stability and permeability of the refractive index, which is preferable.

Further, the optical waveguide of the present invention may be provided with an optical path conversion mirror that converts the optical path into an optical axis of about 90° on the optical axis of the core pattern, and may also be a composite optical composite substrate formed by combining various electrical wiring boards. Used to bond to an optical fiber via a connector or the like Into the cable.

[The lower cladding layer. Upper cladding layer]

The lower cladding layer and the upper cladding layer used in the optical waveguide of the present invention are disposed so as to cover at least the lower surface and the upper surface of the core pattern, and are preferably disposed so as to further cover the two side walls.

The method for forming the lower cladding layer and the upper cladding layer is not particularly limited, and examples thereof include a resin layer for forming a coating layer in which a varnish is applied, or a resin layer for forming a coating layer for laminating or pressing a coating layer. A method of forming a lower cladding layer by laminating it on the object to be written. From the viewpoint of curing after coating or lamination, a thermosetting resin, a photocurable resin, a photocurable resin, and the like are preferably used.

The thickness of the lower cladding layer is not particularly limited, and is preferably 5 μm or more from the viewpoint of optical limitations of the core pattern, and is preferably 200 μm or less from the viewpoint of formation of a thick resin layer. good. From the viewpoint of the control of the thickness, it is more preferably 10 μm or more and 150 μm or less, and further preferably 10 μm or more and 100 μm or less from the viewpoint of low-profile.

Further, the lower cladding layer may be a single layer or a plurality of layers, and may be the same material as the upper cladding layer described later or may be a different material.

The thickness of the upper cladding layer is not particularly limited. When the thickness of the upper surface of the core pattern is 5 μm or more, it is preferable from the viewpoint of optical limitations, and the thickness of the resin layer for forming a cladding layer to be used is From the viewpoint of the formability of the thick resin layer, it is preferably 200 μm or less. From the point of view of the control of thickness, if It is more preferably 10 μm or more and 150 μm or less, and further preferably 10 μm or more and 100 μm or less from the viewpoint of low-profile.

[core pattern]

The core pattern 3 used in the optical waveguide of the present invention has a higher refractive index than the lower cladding layer 2 and the upper cladding layer 6, and is a main portion of the propagating light.

From the above viewpoints, it is sufficient to have transparency to the extent that the propagation of light does not adversely affect the propagation of light.

The material of the core pattern is not particularly limited as long as it satisfies the above-mentioned quartz, glass, resin, etc., and when it is formed into a pattern, it is preferable to use a transparent resin from the viewpoint of adhesion and formability. As a method of forming a core pattern, a resin for forming a varnish-like core pattern can be applied to a target (lower cladding layer); or a resin for forming a core pattern of a film can be laminated by lamination, pressing, or the like, and then used. A pattern is formed by performing photolithography or etching (dry etching) of exposure, etching, or the like, or by coating a film or varnish-like core pattern forming resin or the like only at a desired position. From the viewpoint of the high-precision positioning, the photolithography process is preferably exemplified. From this viewpoint, the resin for forming the core pattern is preferably an etchable resin layer, and more preferably a photosensitive resin layer.

Further important in the above range is that the periphery of the two sides of the core pattern is a material which can form a low refractive index portion having a refractive index lower than the center of the core pattern.

The cross-sectional shape of the core pattern may be a rectangular shape (quadrilateral shape), a polygon, a circle, an ellipse or the like. In the case of a polygon other than a rectangle, it is preferable that a low refractive index portion is formed around the two sides or more. It is preferable to form a low low refractive index portion as far as possible around the polygon. In the case of a circle or an ellipse, it is preferable that one or more of the surrounding portions are low refractive index portions, and more preferably all of the surrounding portions are low. Refractive index part. In the case where the core pattern is formed by the above-described photolithography, it is preferable because it is formed in a rectangular shape.

The thickness of the core pattern is not particularly limited, and if the thickness of the core pattern after formation is 10 μm or more, there is an advantage that the positioning can be expanded in combination with the light-receiving element or the optical fiber or the optical element after the optical element is formed. The tolerance, if it is 160 μm or less, has the advantage that after the formation of the optical element, in combination with the light-receiving element or the optical fiber or the optical element, the bonding efficiency is improved, and the propagation light which can be generated by total reflection is provided. The effect of reducing the phase difference reduces the light propagation loss. From the above viewpoints, the thickness of the core pattern is preferably from 10 μm to 160 μm, more preferably from 20 μm to 100 μm, still more preferably from 30 μm to 80 μm.

[etching solution]

The etching solution is not particularly limited, and examples thereof include an organic solvent-based etching solution such as an organic solvent or a semi-aqueous etching solution containing an organic solvent and water, an alkaline aqueous solution, and an alkaline semi-aqueous system containing an alkaline aqueous solution and one or more organic solvents. An alkaline etching solution such as an etching solution. Further, the etching temperature can be adjusted in accordance with the etching property of the resin layer for forming a core pattern.

The organic solvent is not particularly limited, and examples thereof include organic solvents and the like listed in the above solution.

These organic solvents may be used singly or in combination of two or more. and Further, a surfactant, an antifoaming agent, a refractive index reducing agent, or the like may be mixed in the organic solvent.

The base of the basic aqueous solution is not particularly limited, and examples thereof include the above-mentioned bases and the like.

These bases may be used singly or in combination of two or more.

The pH of the alkaline aqueous solution used in the etching is preferably 9 to 14. Further, a surfactant, an antifoaming agent, a refractive index reducing agent, or the like may be mixed in the alkaline aqueous solution.

The alkaline semi-aqueous etching solution is not particularly limited as long as it contains an alkaline aqueous solution and one or more organic solvents. The pH of the alkaline semi-aqueous etching solution is preferably as small as possible within a range in which etching can be sufficiently performed, preferably pH 8 to 13, more preferably pH 9 to 12.

The concentration of the organic solvent is usually preferably from 2% by mass to 90% by mass. Further, a small amount of a surfactant, an antifoaming agent, or the like may be mixed in the alkaline semi-aqueous etching solution, and a refractive index reducing agent or the like may be mixed.

The treatment after the etching may be carried out by using the organic solvent, a semi-aqueous cleaning solution containing the organic solvent and water, or water or an acidic solution. The refractive index reducing agent excessively impregnated into the transparent resin can also be removed to some extent by the cleaning.

In the case of the above transparent resin, if the transparent resin is washed by an acidic solution, excess potassium ions or sodium ions can be removed, and potassium ions or sodium ions in the outermost layer portion can be further removed (if the carboxylate is acidified) The solution becomes a carboxylic acid, Further, since the hydrophobicity is improved and the substitution of potassium or sodium is not carried out to the inside, it is preferable because potassium ions or sodium ions are substantially retained in the vicinity of the surface layer portion of the transparent resin.

Hereinafter, each step used in the method for producing an optical member of the present invention will be described in detail.

[Step A, Step A']

As step A used in the method for producing an optical member of the present invention, the transparent member is exposed to the solution so that the refractive index of the exposed portion of the transparent member exposed is substantially lower than the transparent member of the transparent member which is not the exposed portion. The refractive index of the center. The method of exposing the solution is not particularly limited, and examples thereof include a spray method, a dipping method, a liquid coating method, a spin coating method, a brush coating method, and a scraping method. Moreover, the methods can also be used in combination as needed.

Thereby, a portion having a different refractive index exposed to the solution can be formed substantially uniformly. Moreover, by using the solution, the exposed surface of the transparent member having a complicated shape or an intricate shape can also substantially reduce the refractive index, and can also make the surface portion of the side of the core pattern of the optical waveguide or the like. The refractive index in the vicinity is substantially reduced.

In the step A' of the method for producing another optical member of the present invention, in the transparent member, the surface layer portion of the transparent member contains a refractive index controlling agent which substantially reduces the refractive index of the transparent member, so that the refractive index control can be contained. The refractive index of the surface portion of the agent is substantially lower than the refractive index of the central portion of the transparent member. The method of adding the refractive index controlling agent includes a method of previously including a refractive index controlling agent in the vicinity of a surface layer portion of the transparent member, and is transparent to various known methods (for example, sputtering). a method of embedding a refractive index controlling agent in the member; or exposing the liquid refractive index controlling agent or the refractive index controlling agent dissolved in the solution to the transparent member as shown in the above step A, at the surface portion of the transparent member A method of containing the refractive index controlling agent in the vicinity.

If it is a method contained in advance, it is preferable from the viewpoint of controlling the refractive index at an arbitrary position, and it is preferable to control the refractive index of the liquid layer from the viewpoint of lowering the refractive index of the surface layer of the transparent member under uniform conditions. The method of exposing the agent or the refractive index controlling agent dissolved in the solution to the transparent member.

[Step B]

As the step B used in the method for producing an optical member of the present invention, the transparent member can be etched by the etching liquid, and the step B of patterning by etching can be included. Since the step of patterning by etching is included, it is easy to obtain a transparent member having an arbitrary shape, and the shape processing can be collectively performed, which is preferable. The etching method is not particularly limited. If a portion which can be etched by the etching liquid and a portion which cannot be etched are prepared in advance, the etchable portion can be removed by the etching liquid, for example, by performing the following method: a pattern-shaped etching resist is formed on the transparent member, and a portion where the resist is not etched is removed by etching; or an uncured portion and a hardened portion (including photohardening) are formed on the transparent member by using light or heat. Then, the uncured portion is removed by an etching solution. Further, the method of immersing the etching liquid is not particularly limited, and examples thereof include a spray method, a dipping method, a liquid coating method, a spin coating method, a brush coating method, and a scraping method. And these methods can also be used together as needed.

The above step A or step A' may be performed simultaneously with step B or after step B, whereby the surface layer of the patterned transparent member may be refracted The rate is substantially reduced. When the step A or the step A' is performed after the step B, if the etching treatment and the exposure solution are continuously performed, the optical member of the present invention can be efficiently produced; but if the step A or the step A' is the same as the step B If it is carried out, the work efficiency can be improved by reducing the number of steps, which is preferable. From the above viewpoints, in the case where the step B is carried out simultaneously with the step A or the step A', the etching liquid may be the same as the above-mentioned solution which can substantially reduce the refractive index or a mixture of the above.

[Step C]

In the step C used in the method for producing an optical member of the present invention, when the transparent member is a photosensitive transparent resin, the step C is included before the step A or the step A' or before the step B, that is, The actinic radiation that can be photohardened is irradiated. Thereby, even if it is exposed to a solution, it can improve the solution resistance by photohardening by photochemical ray. Further, the etching resistance to the etching liquid at the time of patterning by etching is improved. By making the solution and the etching liquid the same liquid (may also be a mixed liquid), the steps A and B can be simultaneously performed, so that the workability is improved.

The actinic ray used for photohardening of the photosensitive transparent resin may be light having a wavelength at which the photosensitive transparent resin can be cured, and examples thereof include ultraviolet light, visible light, and infrared light. If it is an ultraviolet ray, photohardening can be performed efficiently, and it is preferable. The amount of irradiation of the actinic ray is not particularly limited, and is preferably 10 mJ/cm ² to 10000 mJ/cm ² , more preferably 30 mJ/cm ² to 5000 mJ/cm ² , and is 40 mJ/cm ² to 4000 mJ/ Cm ² is even better. Further, in the case of patterning by etching, after patterning, the actinic ray may be further irradiated to perform photocuring. The amount of irradiation at this time is not particularly limited, and is preferably 100 mJ/cm ² to 10000 mJ/cm ² , more preferably 300 mJ/cm ² to 5000 mJ/cm ² , and is 400 mJ/cm ² to 4000 mJ/cm. ² is even better. By patterning and exposure, the adhesion of the pattern and the like can be improved.

[Step D]

In the step D used in the method for producing another optical member of the present invention, when the transparent member is a transparent resin, and the transparent member can be cured by heat, the transparent resin is heat-hardened to be thermally cured. The refractive index in the vicinity of the surface layer portion of the transparent resin is substantially lower than the refractive index in the central portion of the transparent resin after the heat curing.

Further, as the step D', the step of thermally hardening the transparent resin may be included after the step A or the step A'. When the thermal curing is performed, the unreacted photohardening component and the thermosetting component can be hardened by heat, and the exposed and impregnated refractive index reducing agent can be fixed to some extent.

The temperature of the step D or the heat curing of the step D' is not particularly limited. If it is 40 ° C to 280 ° C, the transparency of the resin is easily maintained. If it is 80 ° C to 200 ° C, it is more preferably 100 ° C to 190 ° C. Further better. If the heating time is 5 minutes to 5 hours, it may be thermally hardened, and it is more preferably 20 minutes to 3 hours, and further preferably 30 minutes to 2 hours.

The method for measuring the refractive index of the transparent member of the present invention is not particularly limited, and the measurement may be carried out by the following method. First, the sample for refractive index measurement can be produced by any of the following methods (1) to (3).

(1) separately produced low refractive index treatment (exposure, impregnation solution, including A transparent member having a refractive index reducing agent, a sample subjected to a low refractive index treatment, and each refractive index was measured.

(2) After covering a part of the surface of the transparent member, a low refractive index treatment is performed, and the refractive index of the uncoated transparent member is measured, and the refractive index of the coated transparent member is removed.

(3) After the transparent member was subjected to a low refractive index treatment, the transparent member was broken, and the refractive index of the transparent member in the vicinity of the surface layer portion and the center portion was measured.

The measurement method of the refractive index may be carried out by a known method, and a minimum declination method, a critical angle method, an interference method (low coherence interference method, phase shift interference method, or the like) may be used.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but not limited to these examples.

{Example 1}

<Production of Resin Film for Forming Transparent Member>

[Matrix Polymer for Forming Transparent Member: Production of (Meth)Acrylic Polymer (P-1)]

42 parts by mass of propylene glycol monomethyl ether acetate and 21 parts by mass of methyl lactate were weighed in a flask equipped with a stirrer, a condenser, an air tube, a dropping funnel, and a thermometer, and stirred while introducing nitrogen gas. The liquid temperature was raised to 65 ° C, and 14.5 parts by mass of N-cyclohexylmaleimide, 20 parts by mass of benzyl acrylate, 1.5 parts by mass of o-phenylphenol, 39 parts by mass of acrylate, and methacrylic acid were added dropwise over 3 hours. -2-hydroxyl 14 parts by mass of ethyl ester, 12.5 parts by mass of methacrylic acid, 4 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile), 37 parts by mass of propylene glycol monomethyl ether acetate, and lactate A A mixture of 21 parts by mass of the ester was stirred at 65 ° C for 3 hours, and further stirred at 95 ° C for 1 hour to obtain a (meth)acrylic polymer (P-1) solution (solid content: 45 mass%). .

[Measurement of acid value]

The result of measuring the acid value of P-1 was 80 mgKOH/g. Further, the acid value was calculated from the amount of 0.1 mol/L potassium hydroxide aqueous solution required for neutralizing the P-1 solution. At this time, the point at which the phenolphthalein added as an indicator was changed from colorless to pink was used as a neutralization point.

[Measurement of Weight Average Molecular Weight]

The result of measuring the weight average molecular weight of P-1 (standard polystyrene conversion) using GPC ("SD-8022", "DP-8020", and "RI-8020" manufactured by Tosoh Co., Ltd.) is 3.2 × 10 ⁴ . In addition, "Gelpack GL-A150-S" and "Gelpack GL-A160-S" manufactured by Hitachi Chemical Co., Ltd. are used for the pipe string. The elution liquid was measured using tetrahydrofuran, the sample concentration was set to 0.5 mg/ml, and the dissolution rate was set to 1 ml/min. The result is 32,000.

[Preparation of resin varnish for forming transparent members]

The P-1 solution (solid content: 45 mass%) of the (A) alkali-soluble (meth)acrylic polymer containing a maleic imine skeleton in the main chain was weighed in a plastic bottle of a wide mouth. And 40 parts by mass of bisphenol A type epoxy acrylate (EA-1010N manufactured by Shin-Nakamura Chemical Co., Ltd.) (epoxy equivalent: 518 g/eq) as (B) polymerizable compound,

1-[4-(2-Hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one as (D) polymerization initiator (Ciba Specialty) 1 part by mass of Irgacure 2959) manufactured by Chemicals Co., Ltd., bis(2,4,6-trimethylbenzylidene)phenylphosphine oxide (Irgacure 819 manufactured by Ciba Specialty Chemicals Co., Ltd.) 1 part by mass The mixture was stirred for 6 hours at a temperature of 25 ° C and a number of revolutions of 400 rpm using a stirrer to prepare a resin varnish for core formation. Thereafter, a polytetrafluoroethylene filter having a pore size of 2 μm (PF020 manufactured by Advantec Toyo Co., Ltd.) and a membrane filter having a pore size of 0.5 μm were used (Aiduobang Deco Co., Ltd.) The manufactured J050A) was subjected to pressure filtration under the conditions of a temperature of 25 ° C and a pressure of 0.4 MPa. Then, vacuum defoaming was performed for 15 minutes under the conditions of a reduced pressure of 50 mmHg using a vacuum pump and a bell jar to obtain a resin varnish for forming a transparent member.

[Production of Resin Film for Forming Transparent Member]

The resin varnish for forming a transparent member was applied to a PET film (A1517 manufactured by Toyobo Co., Ltd., thickness: 16 μm) by using a coater (Multicoater TM-MC manufactured by HIRANO TECSEED Co., Ltd.). On the surface, drying was carried out at 100 ° C for 20 minutes, and then a release film as a protective film (A31 manufactured by Teijin DuPont Films Co., Ltd., thickness: 25 μm) was attached to obtain a transparent member. A resin film is used. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coater, and in the present embodiment, the film thickness after curing is adjusted to 50 μm.

[Measurement of Refractive Index]

The obtained resin film for forming a transparent member was cut into a size of 100 mm × 100 mm, and an ultraviolet exposure machine (manufactured by ORC Co., Ltd., EXM-1172) was used for the self-supporting film side, and ultraviolet rays were irradiated at 3,500 mJ/cm ² (wavelength: 365 nm). ). Thereafter, the support film was peeled off, immersed in a 1.0% by mass aqueous potassium carbonate solution (liquid temperature: 30 ° C) for 3 minutes, and then washed with pure water. Next, heat drying and hardening were performed at 160 ° C for 1 hour, and the protective film was peeled off to form an optical member.

The refractive index at a wavelength of 830 nm of the support film surface (the potassium carbonate aqueous solution impregnation surface) of the optical member was measured using a tantalum-coupled refractometer (manufactured by Metricon Co., Ltd., trade name: Model 2020), and the refractive index was 1.556. The measurement of any position at 20 (the position separated by about 1 cm) is also the same refractive index, and there is no positional inhomogeneity. Infrared (IR) measurement of the surface was carried out, and as a result, the peak of the carboxylate anion was observed, and energy dispersive X-ray analysis (EDX) was measured, and as a result, potassium was detected. The refractive index of the protective film surface (non-impregnated surface of the aqueous solution of potassium carbonate) was 1.558, and the same refractive index was measured at any of 20 positions (positions separated by about 1 cm), and there was no positional unevenness. The surface IR measurement was carried out, and as a result, there was no carboxylate anion. The peak value was measured by EDX, and no potassium was detected as a result. EDX analysis was carried out in the depth direction, and potassium was detected from the surface up to 5 μm. Further, the film was heated at 160 ° C for 2 hours, and the refractive index was measured at any other position by the same method as described above. As a result, the support film surface side was 1.556, and the protective film surface side was 1.558, which did not change.

In addition, a resin film for forming a transparent member was produced in the same manner as described above except that the heat treatment was not performed, and the protective film was peeled off to form an optical member. The refractive index of the support film surface (the potassium carbonate aqueous solution impregnation surface) at a wavelength of 830 nm was measured by the same method as above, and as a result, it was 1.552, and the refractive index of the protective film surface was 1.549.

{Example 2}

In the first embodiment, an optical member was produced by the same method except that a 1.0 mass% potassium carbonate aqueous solution was changed to a 1.0 mass% sodium carbonate aqueous solution.

The refractive index at a wavelength of 830 nm of the support film surface (the sodium carbonate aqueous solution impregnation surface) of the optical member was measured using a 稜鏡-type refractometer (manufactured by Metricon Co., Ltd., trade name: Model 2020), and the refractive index was 1.556. The position (position separated by about 1 cm) is also the same refractive index, and there is no positional inhomogeneity. When the surface IR measurement was performed, the peak of the carboxylic acid anion was observed, and EDX measurement was performed, and as a result, sodium was detected. The refractive index of the protective film surface (non-impregnated surface of the aqueous sodium carbonate solution) was 1.558, and the same refractive index was measured at any of the 20 positions (the positions separated by about 1 cm), and there was no positional unevenness. When the surface IR measurement was performed, the peak of the carboxylate anion was not observed, and the EDX measurement was performed, and no sodium was detected. EDX analysis in the depth direction, the result is straight from the surface Sodium was detected to a position of 5 μm. Further, the film was heated at 160 ° C for 2 hours, and the refractive index was measured at any other position by the same method as described above. As a result, the support film surface side was 1.556, and the protective film surface side was 1.558, which did not change.

In addition, a resin film for forming a transparent member was produced in the same manner as described above except that the heat treatment was not performed, and the protective film was peeled off to form an optical member. The refractive index at a wavelength of 830 nm of the support film surface (the sodium carbonate aqueous solution impregnation surface) was measured by the same method as above, and as a result, it was 1.552, and the refractive index of the protective film surface was 1.549.

{Example 3}

<Preparation of resin film for forming a cladding layer>

[(A) Matrix Polymer: Production of (Meth)acrylic Polymer (A-1)]

In a flask equipped with a stirrer, a condenser, an air guide tube, a dropping funnel, and a thermometer, 46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate were weighed and stirred while introducing nitrogen gas. The liquid temperature was raised to 65 ° C, and 47 parts by mass of methyl methacrylate, 33 parts by mass of butyl acrylate, 16 parts by mass of 2-hydroxyethyl methacrylate, and 14 parts by mass of methacrylic acid were added dropwise over 3 hours. 3 parts by mass of 2'-azobis(2,4-dimethylvaleronitrile), 46 parts by mass of propylene glycol monomethyl ether acetate, and 23 parts by mass of methyl lactate, and then carried out at 65 ° C After stirring for an hour, the stirring was further continued at 95 ° C for 1 hour to obtain a (meth)acrylic polymer (A-1) solution (solid content: 45 mass%).

[Measurement of Weight Average Molecular Weight]

The weight average molecular weight (standard polystyrene conversion) of (A-1) measured by GPC ("SD-8022", "DP-8020", and "RI-8020" manufactured by Tosoh Corporation) was 3.9. ×10 ⁴ . In addition, "Gelpack GL-A150-S" and "Gelpack GL-A160-S" manufactured by Hitachi Chemical Co., Ltd. are used for the pipe string.

[Measurement of acid value]

The result of measuring the acid value of (A-1) was 79 mgKOH/g. Further, the acid value was calculated from the amount of 0.1 mol/L potassium hydroxide aqueous solution required for neutralizing the A-1 solution. At this time, the point at which the phenolphthalein added as an indicator was changed from colorless to pink was used as a neutralization point.

[Preparation of resin varnish for coating layer formation]

84 parts by mass of the (A-1) solution (solid content: 45 mass%) as the (A) matrix polymer (solid content: 38 parts by mass), and (B) photohardenable component having a polyester skeleton 33 parts by mass of (meth)acrylic acid urethane ("U-200AX" manufactured by Shin-Nakamura Chemical Co., Ltd.) and (meth)acrylic acid urethane having a polypropylene glycol skeleton (Xinzhongcun Chemical Industry) 15 parts by mass of "UA-4200" manufactured by the company, and the isocyanurate type terpolymer which protects hexamethylene diisocyanate by methyl ethyl ketone oxime as (C) thermosetting component 20 parts by mass of a polyfunctional block isocyanate solution (solid content: 75% by mass) ("Sumidur BL3175" manufactured by Sumika Bayer Urethane Co., Ltd.) (solid content: 15 parts by mass) ), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one as (D) photopolymerization initiator (Ciba Japan shares) "Irgacure 2959" manufactured by Ciba Japan KK), 1 part by mass of bis(2,4,6-trimethylbenzylidene)phenylphosphine oxide (manufactured by Ciba Japan Co., Ltd.) The "Irgacure 819") 1 part by mass, and as diluted with 23 parts by mass of propylene glycol monomethyl ether acetate of an organic solvent was mixed while stirring. After pressure filtration using a polytetrafluoroethylene filter ("PF020" manufactured by Aibangbond Co., Ltd.) having a pore size of 2 μm, pressure reduction and defoaming were carried out to obtain a resin varnish for forming a coating layer.

The resin composition for forming a cladding layer obtained above was applied to a PET film as a carrier film (COSMOSHINE A4100 manufactured by Toyobo Co., Ltd.) using a coater (Multicoater TM-MC, manufactured by HIRANO TECSEED Co., Ltd.). The non-treated surface having a thickness of 50 μm was dried at 100 ° C for 20 minutes, and then a surface-release PET film as a cover film (Purex A31 manufactured by Teijin DuPont Film Co., Ltd.) and having a thickness of 25 μm), a resin film for forming a cladding layer was obtained. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coater, and the thicknesses of the lower cladding layer 2 and the upper cladding layer 6 used in the present embodiment are described in the examples. Further, the film thickness after curing of the lower cladding layer 2 and the upper cladding layer 6 is the same as the film thickness after coating.

[Measurement of Refractive Index]

A resin film for forming a cladding layer was formed on the substrate (having a size of 60 mm × 20 mm and a thickness of 0.6 mm) and cured to prepare a sample for refractive index measurement. The refractive index of the sample at a wavelength of 830 nm was measured using a ruthenium combined refractometer (manufactured by Metricon Co., Ltd., trade name: Model 2020). The measurement is performed at a predetermined fixed temperature (for example, 25 ° C) in the range of 15 ° C to 30 ° C. The resin layer after hardening had a refractive index of 1.496.

<Example of fabrication of optical waveguide of Fig. 1>

[Formation of lower cladding layer 2]

A 100 mm × 100 mm polyimine film (polyimine: Kapton EN, thickness: 25 μm) was used as the substrate 1, and the protective film of the resin film for forming a 15 μm-thick coating layer obtained above was peeled off, and vacuum was applied thereto. Pressure laminating machine (manufactured by Nago Seisakusho Co., Ltd., MVLP-500), after being vacuumed at 500 Pa or less, heated at a pressure of 0.4 MPa, a temperature of 90 ° C, and a pressurization time of 30 seconds. Crimp-bonded and laminated on one of the faces of the substrate 1. Then, ultraviolet rays (wavelength: 365 nm) were irradiated from the support film side of the resin film A at 3000 mJ/cm ² using an ultraviolet exposure machine (manufactured by ORC Co., Ltd., EXM-1172). Thereafter, the support film was peeled off, and dried and hardened at 170 ° C for 1 hour to form a lower cladding layer 2 .

[Formation of Core Pattern 3]

The resin film for forming a transparent member having a thickness of 50 μm obtained as described above was used as a resin film for forming a core pattern, and the protective film was peeled off, and then a roll bonding machine (manufactured by Hitachi Plant Techno Co., Ltd.) was used. , HLM-1500), laminated on the lower cladding layer 2 forming surface under the conditions of a pressure of 0.4 MPa, a temperature of 50 ° C, and a laminating speed of 0.2 m/min, using a vacuum pressurizing laminating machine ( Manufactured by Nago Seiki Co., Ltd., MVLP-500), after vacuuming at 500 Pa or less, it was laminated by heating and pressure bonding under the conditions of a pressure of 0.4 MPa, a temperature of 65 ° C, and a pressurization time of 30 seconds. Then, using a UV exposure machine (manufactured by ORC Co., Ltd., EXM-1172), a negative mask having an opening of 50 μm × 90 mm × 12 (with a distance of 250 μm) was interposed, and ultraviolet rays were irradiated at 3,500 mJ/cm ² ( The wavelength is 365 nm). Next, the support film was peeled off, and etching was performed for 3 minutes in a 1.0 mass% potassium carbonate aqueous solution (liquid temperature: 30 ° C) to remove the uncured portion of the core pattern forming resin, followed by 1.0% sulfuric acid and pure Wash the water. Then, it was heat-dried and hardened at 160 ° C for 1 hour to form a core pattern having a height of 50 μm and a width of 50 μm.

[Formation of upper cladding layer 6]

After the protective film of the resin film for forming a cladding layer having a thickness of 75 μm obtained as described above was peeled off from the side of the core pattern forming surface, a vacuum pressure type laminator (manufactured by Naji Seisakusho Co., Ltd., MVLP-500) was used. After forming a vacuum of 500 Pa or less, lamination was carried out by heating and pressure bonding under the conditions of a pressure of 0.4 MPa, a temperature of 90 ° C, and a press time of 30 seconds. Then, ultraviolet rays (wavelength: 365 nm) were irradiated from the support film side of the resin film A at 3000 mJ/cm ² using an ultraviolet exposure machine (manufactured by ORC Co., Ltd., EXM-1172). Thereafter, the support film was peeled off, and dried and hardened at 170 ° C for 1 hour to form an upper cladding layer 6 as an optical waveguide.

[shape processing]

Using a wafer dicing machine (DAC 552, manufactured by DISCO Co., Ltd.), the core pattern of the optical waveguide obtained above was cut together with the substrate so as to be 80 mm, and the end surface was smoothed to produce an optical waveguide.

[Light loss measurement]

One of the core pattern end faces of the obtained optical waveguide is irradiated with light of 850 nm using the fiber of GI50, and the optical fiber of SI114 is received from the other end face. Light, the optical loss of the optical waveguide. As a result, the average was 0.05 dB/cm. One side of the obtained optical waveguide is incident on white light, and the end face of the core pattern of the other surface is observed. As a result, the brightness of the center of the core pattern is high (above the upper side and the side (from the interface between the core pattern and the upper cladding layer 5 μm) The range of the core pattern has a low brightness). When the EDX measurement of the cross section was performed, potassium was detected at a position of 5 μm from both sides and the upper side, and the refractive index at the position of the potassium was detected to be 1.556, and the refractive index at the center of the core pattern of the potassium was not detected to be 1.558.

{Comparative example 1}

In Example 3, an optical waveguide was produced by the same method except that the core pattern was formed by etching and then washed with a 1.0% aqueous solution of calcium chloride.

[Light loss measurement]

From one of the core pattern end faces of the obtained optical waveguide, light of a wavelength of 850 nm is incident using an optical fiber of GI50, and light output from the other end face is received by an optical fiber of SI114 to produce optical loss of the optical waveguide. As a result, the average was 0.42 dB/cm. One of the faces of the obtained optical waveguide is incident on white light, and the end face of the core pattern of the other face is observed. As a result, the brightness of the center of the core pattern is low (the brightness of the core pattern near the upper side and the side is high). When the EDX measurement of the cross section was performed, calcium was detected at a position of 5 μm from both sides and the upper side, and the refractive index at the position where calcium was detected was 1.559, and the refractive index at the center portion of the core pattern of calcium was not detected to be 1.558. As described above, it was confirmed that the refractive index of the site containing the divalent calcium cation is higher than that of the central portion, and the crosslinking of the transparent member is promoted by ion crosslinking or the like unlike the monovalent cation. Therefore, the light propagation loss of the optical waveguide becomes high, and the effect of the present invention cannot be achieved.

(industrial availability)

According to the method for producing an optical member of the present invention, it is possible to provide an optical member having a small unevenness in the position of the refractive index in the vicinity of the surface layer portion of the transparent member. Moreover, the optical waveguide having low optical loss can be provided by the present invention. Therefore, it can be applied to a wide range of fields such as an antireflection member, an antireflection film, various optical films, various optical devices, optical waveguide members, photoelectric composite members, optical cables, and optical interconnections.

1‧‧‧Substrate

2‧‧‧Lower coating

3‧‧‧ core pattern

4‧‧‧ core pattern center

5‧‧‧Low refractive index

6‧‧‧Upper cladding

Claims (19)

A method of producing an optical member, comprising the step A: exposing a transparent member comprising a transparent resin to an alkali solution such that a refractive index of a surface portion of the transparent member exposed to the alkali solution is substantially lower than The refractive index of the central portion of the transparent member exposed to the alkali solution. The method for producing an optical member according to claim 1, wherein in the step A, when the transparent member is exposed to the alkali solution, the alkali solution is impregnated into the transparent member. in. The method for producing an optical member according to claim 2, wherein the alkali solution contains a refractive index controlling agent, and the refractive index controlling agent exhibits a surface layer portion contained in the transparent member. The function of substantially reducing the refractive index of the surface layer portion. The method of producing an optical member according to claim 3, wherein the refractive index controlling agent is a monovalent cation. A method for producing an optical member, comprising the step A' of: in a transparent member, a surface layer portion of the transparent member contains a monovalent cation as a refractive index controlling agent which substantially reduces a refractive index of the transparent member, thereby The refractive index of the surface layer portion containing the refractive index controlling agent is substantially lower than the refractive index of the central portion of the transparent member not containing the refractive index controlling agent. The method for producing an optical member according to any one of the items 1 to 5, wherein the transparent member is a transparent member etchable by an etching solution, and the optical member is manufactured Including patterning by etching Step B, the step B is performed simultaneously with the step A or the step A', or before the step A or the step A'. The method for producing an optical member according to the invention of claim 4, wherein the monovalent cation is at least one of a potassium ion and a sodium ion. The method for producing an optical member according to claim 6, wherein the transparent resin is a photosensitive transparent resin, which is included before the step A or the step A', or/and before the step B Step C: Irradiating the actinic ray which can photoharden the photosensitive transparent resin. The method for producing an optical member according to Item 4 or 5, wherein the step A' is followed by the step D': thermally curing the transparent resin. The method for producing an optical member according to claim 9, wherein the transparent resin contains at least (A) a matrix resin having a thermally polymerizable functional group, and (B) a thermally polymerizable compound. A transparent member for forming an optical member, which is used in a method of producing an optical member according to any one of claims 1 to 10. An optical member obtained by the method for producing an optical member according to any one of claims 1 to 10. An optical waveguide, which is an optical waveguide including a core portion and a cladding portion, and in a core pattern forming the core portion, at least one portion of the periphery of the core pattern includes a surface layer portion, wherein the surface layer portion has a ratio The central portion of the core pattern has a low refractive index and contains a monovalent cation as a refractive index controlling agent. The optical waveguide according to claim 13, which is an optical waveguide in which a lower cladding layer, the core pattern, and an upper cladding layer are laminated, and includes a refractive index on the outer side of the surface layer portion having a low refractive index. The lower cladding layer or/and the upper cladding layer are lower in rate. The optical waveguide according to claim 13, wherein the core pattern having two or more sides is a core pattern including at least two side walls. The optical waveguide according to claim 14, wherein the low refractive index portion and the low refractive index portion are compared with a refractive index difference between a center of the core pattern and a low refractive index portion around the core pattern. The difference in refractive index between the lower cladding layer and/or the upper cladding layer is greater. The optical waveguide according to any one of the preceding claims, wherein the core pattern is formed by a transparent member for forming an optical member according to claim 11 of the invention. An optical module using the optical waveguide according to any one of claims 13 to 17. A transparent member for forming an optical waveguide core pattern, which is a transparent member for forming a core pattern in an optical waveguide in which a lower cladding layer, a core pattern, and an upper cladding layer are laminated, by forming the core pattern by A monovalent cation is contained as a refractive index controlling agent around two or more sides, and a surface layer portion having a refractive index lower than a central portion of the core pattern can be substantially formed.