JP2005099514A - Method for manufacturing optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical waveguide in which the optical waveguide having small light loss can be manufactured through simple processes. <P>SOLUTION: The method for manufacturing the optical waveguide includes the stages of: forming an intermediate clad layer 2 of resin on the top surface side of a lower clad material 1 made of a glass substrate; forming a nearly rectangularly-sectioned hole part 2a extending in the propagation direction of light in the intermediate clad layer 2; charging thermo/ultraviolet-ray setting resin 7 which contains at least either of a photopolymerization initiator and a thermal polymerization initiator and has a larger refractive index than the lower clad material 1 and intermediate clad layer 2 in the hole part 2a to coat the top surface side of the intermediate clad layer 2 with the thermal/ultraviolet-ray setting resin 7; and forming a core part 4 and an adhesive layer 5 in one body by setting the thermal/ultraviolet-ray setting resin 7 while the resin is joined with an upper clad material 3 made of a glass substrate which is nearly equal in refractive index to the lower clad material 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an optical waveguide constituting an optical device used in the fields of optical communication and optical information processing.

As a conventional optical waveguide manufacturing method, as shown in FIG. 5, a concave groove 20 is formed on the upper surface side of a lower clad material 1 made of a quartz glass substrate, and the lower clad material 1 and the upper clad material 1 are formed in the groove 20. A core portion 4 that is filled with an ultraviolet curable resin having a refractive index higher than the refractive index of the clad material 3 as an adhesive 30 and bonded to the upper clad material 3 and becomes a light propagation region by the adhesive 30 in the groove 20. Is forming. (Patent Document 1)
In such a manufacturing method, since the groove 20 is formed in the glass substrate (lower clad material 1) by the photolithography method and the ion etching method, it takes time to form the groove 20, and in particular, the groove portion is several tens μm or more. This tendency becomes significant when a relatively deep groove is formed.

Therefore, as shown in FIG. 6, a high-refractive-index heat / ultraviolet curable resin 7 that becomes the core portion 4 is formed on the lower clad material 1 formed of the first low-refractive index resin or the first low-refractive index glass. After the coating is applied to a predetermined thickness, the core portion 4 of the optical waveguide is formed by ultraviolet exposure using the photomask 8, and then the uncured portion is cured by heat to form the side cladding portion 30. Further, a manufacturing method is known in which the upper clad material 3 is formed by coating a high refractive index resin 40 and bonding a second low refractive index glass. In such a manufacturing method, a glass substrate ( Since the groove is not formed by directly processing the lower clad material 1), the core portion 4 can be formed more easily. (Patent Document 2)
By the way, although the light incident on the core portion 4 propagates while being repeatedly reflected from the clad material having a low refractive index, there is a problem that the light oozes out from the clad material and causes optical loss. In the case of the optical waveguide obtained in (1), the core portion 4 and the upper clad material 3 are bonded via the high refractive index resin 40 having a large light absorption loss, so that there is a problem that the light loss increases.
JP-A-6-88914 JP 2002-71987

  The present invention has been made in view of these points, and an object of the present invention is to provide an optical waveguide manufacturing method capable of manufacturing an optical waveguide with little optical loss by a simple process. It is in.

  In order to solve the above-described problem, an optical waveguide manufacturing method according to claim 1 of the present invention includes a step of forming an intermediate clad layer made of resin on the upper surface side of a lower clad material made of a glass substrate, and an intermediate clad A layer having a substantially rectangular cross section extending in the light propagation direction in the layer, and containing at least one of a photopolymerization initiator and a thermal polymerization initiator in the hole, and having a refractive index of a lower cladding material and an intermediate Filling with heat / ultraviolet curable resin larger than the clad layer and covering the upper surface side of the intermediate clad layer with the heat / ultraviolet curable resin, refracting the thermo / ultraviolet curable resin with the lower clad material And a step of integrally forming the core portion and the adhesive layer by curing in a state of being bonded to an upper clad material made of a glass substrate having substantially the same rate.

  In the method for manufacturing an optical waveguide according to claim 2 of the present invention, the step of forming the intermediate cladding layer and the step of providing the hole portion include a resin containing an uncured photopolymerization initiator on the upper surface side of the lower cladding material. After forming the layer, a mask on which a waveguide pattern is formed is attached to the resin layer and cured by light irradiation, and then the uncured portion is chemically removed to form the intermediate cladding layer and the void portion. It is characterized by being.

  In the method of manufacturing an optical waveguide according to claim 3 of the present invention, the step of forming the intermediate clad layer and the step of providing the hole portions are performed after the uncured resin layer is formed on the upper surface side of the lower clad material, and then transferred. A mold having a waveguide pattern formed on the surface is pressed from the upper surface side and inserted into the uncured resin layer, and the resin layer is cured with the transfer surface in contact with the upper surface side of the lower clad material, and then The mold is opened.

  In the method of manufacturing an optical waveguide according to claim 4 of the present invention, after the step of forming the intermediate cladding layer and the step of providing the hole portion, a resin layer made of a thermoplastic resin is formed on the upper surface side of the lower cladding material. In a state where the resin layer is heated and softened, a mold having a waveguide pattern formed on the transfer surface is pressed from the upper surface side to be inserted into the resin layer, and the transfer surface is brought into contact with the upper surface side of the lower clad material. In this state, the resin layer is cooled and cured, and then the mold is opened.

  According to the optical waveguide manufacturing method of the present invention, since the intermediate cladding layer is made of resin, the mechanical and chemical workability is improved, and the empty space for filling the core portion compared to the glass substrate is obtained. Formation of a hole becomes easy. Also, by forming the core part and the adhesive layer integrally, the core part can be formed and the core part, the intermediate clad layer and the upper clad material can be joined at the same time, and the optical waveguide manufacturing process can be shortened. it can.

  According to the method for manufacturing an optical waveguide according to claim 2, in addition to the effect of claim 1 described above, the formation of the hole portion includes an uncured photopolymerization initiator formed on the upper surface side of the lower clad material. Since the resin layer is cured by irradiating light with a mask having a waveguide pattern formed thereon, it is easy to finely process the mask. A waveguide pattern having a fine core part can be easily obtained. Further, since the uncured portion of the resin layer is chemically removed by development or the like to form the hole portion, the formation process of the hole portion is simplified.

  According to the method for manufacturing an optical waveguide according to claim 3, in addition to the effect of claim 1 described above, the mold having the waveguide pattern formed on the transfer surface is pressed from the upper surface side into the uncured resin layer. After the insertion and curing of the uncured resin layer with the transfer surface in contact with the upper surface side of the lower clad material, the mold is released to form the intermediate clad layer and the voids. There is no need to remove the resin layer to form the hole. Therefore, compared with the case where the hole portion is formed by processing the cured resin layer, the dimensional accuracy of the hole portion is easily ensured, and the dimensional accuracy of the core portion shape is improved. As a result, loss due to scattering can be reduced, and waveguide loss can be reduced.

  According to the method for manufacturing an optical waveguide according to claim 4, in addition to the effect of claim 1, the resin layer formed on the upper surface side of the lower clad material is a thermoplastic resin. The resin with the waveguide pattern formed on the transfer surface is pressed from the upper surface side while being softened by heating and inserted into the resin layer, and the resin is in contact with the upper surface side of the lower clad material. The layer is cooled and cured, and then the mold is opened to obtain an intermediate cladding layer and a void portion, so that the curing time is shortened compared to the case of using a thermosetting resin, and as a result, The optical waveguide manufacturing process is shortened.

The present invention will be described in detail based on the embodiments shown in the drawings.
(Embodiment 1)
FIG. 1 shows a process chart of a method for manufacturing an optical waveguide according to the first embodiment of the present invention. In the figure, 1 is a lower clad material, 2 is an intermediate clad layer, 2a is a hole portion, 3 is an upper clad material, 4 is a core portion, 5 is an adhesive layer, 6 is a resin layer, and 7 is a heat / ultraviolet curable resin. , 8 is a photomask, and 9 is an ultraviolet ray.

  As shown in FIG. 1A, an ultraviolet curable resin containing a photopolymerization initiator is formed on the upper surface side of the lower clad material 1 made of a glass plate such as quartz glass to a thickness of about 5 to 70 μm by spin coating or the like. The resin layer 6 is formed by coating uniformly. As the ultraviolet curable resin containing a photopolymerization initiator, a (meth) acrylic monomer resin having a refractive index substantially the same as that of the lower cladding material 1 (refractive index: 1.45 to 1.60) is preferably used. .

  Next, as shown in FIG. 1B, a photomask 8 in which a predetermined fine waveguide pattern is etched is placed on the resin layer 6, and ultraviolet rays 9 are irradiated from the upper surface side of the photomask 8. As a result, as shown in FIG. 1C, the portions other than the portion covered with the photomask 8 are cured to form the intermediate cladding layer 2. The intermediate clad layer made of resin is provided in this way when the space for filling the core portion (the hole portion 2a in the present invention) is provided between the upper clad 3 and the lower clad 1 rather than the glass substrate. This is because the processability is better mechanically and chemically, and it becomes easier to form a space for filling the core portion than the glass substrate.

  Thereafter, as shown in FIG. 1 (d), the lower clad material 1 is immersed in a developer composed of a mixed solution of ethanol and methyl ethyl ketone, and uncured portions of the resin layer 6 covered with the photomask 8 are removed. The hole 2a is formed by chemical removal. The uncured resin layer 6 is completely removed to the bottom surface side, and the lower clad material 1 is exposed from the bottom surface of the hole portion 2a. The hole 2a has a substantially rectangular cross section and is formed to extend in the light propagation direction.

  Next, as shown in FIG. 1 (e), the hole / hole 2a is filled with a heat / ultraviolet curable resin 7 containing a photopolymerization initiator, and further filled with an injection to fill the hole 2a. As shown in f), the upper surface side of the intermediate cladding layer 2 is covered with a heat / ultraviolet curable resin 7.

  Next, as shown in FIG. 1 (g), an upper clad made of a glass substrate having a refractive index substantially the same as that of the lower clad material 1 from the upper surface side is applied to the heat / ultraviolet curable resin 7 covering the upper surface side of the intermediate clad layer 2. The material 3 is joined. As shown in FIG. 1 (h), the upper clad material 3 is pressed so that the thickness of the heat / ultraviolet curable resin 7 interposed between the intermediate layer 2 and the upper clad 3 becomes 0.05 to 1.5 μm. In this state, ultraviolet rays 9 are irradiated from the lower surface side of the lower clad material 1. The ultraviolet rays 9 pass through the lower clad material 1 that is a glass plate and reach the heat / ultraviolet curable resin 7. Further, in the case where a thermal polymerization initiator is contained in the heat / ultraviolet curable resin 7, heat may be irradiated instead of the ultraviolet light 9, and a photopolymerization initiator and a thermal polymerization initiator may be applied to the ultraviolet curable resin 7. When both are contained, both ultraviolet rays 9 and heat may be irradiated.

As shown in FIG. 1 (i), the heat / ultraviolet curable resin 7 irradiated with ultraviolet rays 9 is cured and filled in the pores 2a due to the effects of the photopolymerization initiator and thermal polymerization initiator contained therein. Is formed with a core portion 4 and an adhesive layer 5 for adhering the core portion 4 between the upper clad 3 and the intermediate clad layer 2 is formed. By integrally forming the core portion 4 and the adhesive layer 5 in this manner, the core portion 4 can be formed and the core portion 4 and the intermediate clad layer 2 can be bonded to the upper clad material at the same time. The process can be shortened. The obtained optical waveguide has a structure in which the lower clad material 1 and the upper clad material 3 are made of a glass substrate with small optical loss, and the core part 4 is directly bonded to both the lower clad material 1 and the upper clad material 2. As a result, the leakage of light can be reduced, and an optical waveguide with little optical loss can be obtained.
(Embodiment 2)
FIG. 2 shows a process chart of a method of manufacturing an optical waveguide according to the second embodiment of the present invention. In the figure, 1 is a lower cladding material, 2 is an intermediate cladding layer, 2a is a hole, 6 is a resin layer, 9 is ultraviolet light, and 10 is a mold.

  In this embodiment, an uncured resin layer 6 made of an ultraviolet curable resin containing a photopolymerization initiator is formed on the upper surface side of the lower clad material 1, and then a mold 10 having a waveguide pattern transferred to the surface is transferred from the upper surface side. A feature is that the intermediate clad layer 2 and the hole 2a are formed by pressing the resin layer 6 into the resin layer 6 and curing the resin layer 6 with the transfer surface in contact with the upper surface side of the lower clad material. Since the other steps are the same as those in the first embodiment, the description thereof is omitted.

  As shown in FIG. 2A, the resin layer 6 formed on the upper surface side of the lower clad material 1 (see the description of FIG. 1A) is pressed and inserted from the upper surface side with a mold 10. In the mold 10, a predetermined fine waveguide pattern 10 a is formed on a pressing surface that is a surface facing the resin layer 6.

  As shown in FIG. 2B, the mold 10 inserted into the uncured resin layer 6 is pressed until the waveguide pattern 10a reaches the upper surface side of the lower clad material 1, and in this state, the resin is Layer 6 is cured to form intermediate cladding layer 2. The intermediate clad layer 2 is formed by irradiating ultraviolet rays 9 from the lower surface side of the lower clad 1. The ultraviolet rays 9 pass through the lower clad material 1 that is a glass plate and reach the resin layer 6. Due to the effect of the contained photopolymerization initiator, the resin layer 6 irradiated with the ultraviolet rays 9 is cured to form the intermediate clad material 2.

  In the present embodiment, an ultraviolet curable resin containing a photopolymerization initiator is also used as the resin layer 6. However, the present invention is not limited to this, and instead, a thermal polymerization initiator or a photopolymerization initiator and a heat A thermosetting resin or a heat / ultraviolet curable resin containing any of the polymerization initiators may be used. In these cases, the intermediate cladding layer 2 can be formed by curing the resin layer 6 with heat instead of curing the resin layer 6 by irradiation with ultraviolet rays 9.

Next, as shown in FIG. 2C, after forming the intermediate cladding layer 2, the mold part 10 is released and released to form the hole part 2 a. By forming the hole portion 2a in this way, the intermediate cladding layer 2 is mechanically processed to provide the hole portion 2a and a part thereof is removed, or the intermediate cladding layer 2 and the uncured resin layer 6 are removed. Need not be removed chemically. Therefore, compared with the case where the hole portion 2a is formed by mechanically and chemically processing, the dimensional accuracy of the hole portion 2a is easily ensured, and as a result, the dimensional accuracy of the core portion shape is improved. In addition, about the following processes, since it is common with the process after the above-mentioned FIG.1 (e), description is abbreviate | omitted.
(Embodiment 3)
FIG. 3 shows a process chart of a method for manufacturing an optical waveguide in the third embodiment of the present invention. In the figure, 1 is a lower clad material, 2 is an intermediate clad layer, 2a is a hole, 10 is a mold, and 11 is a thermoplastic resin layer.

  In the present embodiment, after forming a resin layer 11 made of a thermoplastic resin on the upper surface side of the lower clad material 1, a mold 10 in which a waveguide pattern is transferred to the surface in a state where the resin layer 11 is heated and softened. Is pressed from the upper surface side, and then cooled to harden the resin layer 11 to form the intermediate cladding layer 2 and the hole 2a, and the other steps are the same as in the first embodiment. Therefore, explanation is omitted.

  As shown in FIG. 3A, on the upper surface side of the lower clad material 1 made of a glass plate such as quartz glass, a thermoplastic resin is uniformly coated to a thickness of about 5 to 70 μm by a casting method or the like, The thermoplastic resin layer 11 is formed. As the thermoplastic resin, a thermoplastic resin such as PMMA or PC which is a material (refractive index: 1.45 to 1.60) whose refractive index after curing is substantially the same as that of the lower clad material 1 is preferably used.

  Next, as shown in FIG. 3 (b), the thermoplastic resin layer 11 is heated to the melting start temperature or higher and pressed with the mold 10 from the upper surface side to be inserted into the thermoplastic resin layer 11. . In the mold 10, a predetermined fine waveguide pattern 10 a is formed on a pressing surface that is a surface facing the thermoplastic resin layer 11.

  Next, as shown in FIG. 3C, the mold 10 inserted into the thermoplastic resin layer 11 is pressed until the waveguide pattern 10a reaches the upper surface side of the lower clad material 1, and in this state, heat is applied. The intermediate clad layer 2 is formed by stopping the heating of the plastic resin layer 11 and curing the thermoplastic resin layer 11 by air cooling or water cooling.

Next, as shown in FIG. 3 (d), after the formation of the intermediate cladding layer 2, the cavities 2 a are formed by releasing the pressure by releasing the mold 10. By forming the hole portion 2a in this way, it is not necessary to form the hole portion 2a by mechanical and chemical processing as in the case of the second embodiment, and the dimensional accuracy of the hole portion 2a is ensured. As a result, the dimensional accuracy of the core portion shape is improved, and the thermoplastic resin layer 11 is formed on the upper surface side of the lower clad material 1, so that the thermoplastic resin layer 11 is softened and heated by heating and cooling. Curing can be done quickly and easily. Therefore, the manufacturing process of the intermediate cladding layer 2 and the hole 2a is shortened as compared with the case where a thermosetting resin or the like is used. In addition, about the following processes, since it is common with the process after FIG.1 (e) described in Embodiment 1, description is abbreviate | omitted.
(Embodiment 4)
FIG. 4 shows a process chart of a method for manufacturing an optical waveguide in the fourth embodiment of the present invention. In the figure, 1 is a lower cladding material, 2 is an intermediate cladding layer, 2a is a hole, 8 is a photomask, and 12 is an etching mask layer.

  The present embodiment is characterized in that the intermediate cladding layer 2 and the hole 2a are formed by photolithography, and the other steps are the same as those in the first embodiment, and thus description thereof is omitted.

  As shown in FIG. 4A, a heat (light) curable resin such as a (meth) acrylic resin is applied to the upper surface side of the lower clad material 1 made of a glass plate such as quartz glass by spin coating or the like. The intermediate clad layer 2 is formed by uniformly coating to a thickness of about 5 to 70 μm and then curing. Further, when a thermoplastic resin is used, the intermediate cladding layer 2 can be formed by a casting method. The intermediate clad material 2 is preferably a material whose refractive index is substantially the same as that of the lower clad material 1 (refractive index: 1.45 to 1.60), and the (meth) acrylic resin as the thermo (light) curable resin. PMMA and PC are preferably used as the thermoplastic resin and the thermoplastic resin.

  Next, as shown in FIG. 4B, an etching mask layer 12 is formed on the intermediate cladding layer 2, and a core pattern 12a is formed by photolithography. As a material for the etching mask layer 12, an organic photoresistor or a metal is preferably used.

  Next, as shown in FIG. 4C, the portion of the intermediate cladding layer 2 that is not covered with the etching mask layer 12 is removed by reactive ion etching. The portion not covered with the etching mask layer 12 is completely removed to form a hole portion 2a in which the upper surface side of the lower cladding material 1 is exposed from the bottom surface. Since this hole portion is formed corresponding to the shape of the core pattern 12a, the obtained hole portion 2a is also formed with a pattern extending in the light propagation direction. Since the hole portion 2a is provided using such photolithography, a fine hole portion with high dimensional accuracy can be obtained, and as a result, a core portion with less loss can be formed.

  Next, as shown in FIG. 4D, the etching mask layer 12 is removed. As a result, as shown in FIG. 4E, the upper surface side of the intermediate cladding layer 2 is exposed, and a waveguide can be obtained by performing the steps shown in FIG. 1E and subsequent steps.

It is explanatory drawing which shows the manufacturing process of the optical waveguide in the 1st Embodiment of this invention. It is explanatory drawing which shows the manufacturing process of the optical waveguide in the 2nd Embodiment of this invention. It is explanatory drawing which shows the manufacturing process of the optical waveguide in the 3rd Embodiment of this invention. It is explanatory drawing which shows the manufacturing process of the optical waveguide in the 4th Embodiment of this invention. It is the schematic which shows a prior art example. It is the schematic which shows the prior art example different from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower clad material 2 Intermediate | middle clad layer 2a Air hole part 3 Upper clad material 4 Core part 5 Adhesive layer 6 Resin layer 7 Thermo-UV curing resin 8 Photomask 9 Ultraviolet 10 Mold 11 Thermoplastic resin layer 12 Etching mask layer

Claims (4)

Forming an intermediate clad layer made of a resin on the upper surface side of a lower clad material made of a glass substrate;
Providing an intermediate cladding layer with a substantially rectangular cross section extending in the light propagation direction;
The void portion contains at least one of a photopolymerization initiator and a thermal polymerization initiator, and is filled with a heat / ultraviolet curable resin having a refractive index larger than that of the lower clad material and the intermediate clad layer. Coating the upper surface side of the substrate with the heat / ultraviolet curable resin,
A step of integrally forming the core portion and the adhesive layer by curing the heat / ultraviolet curable resin in a state of being bonded to an upper clad material made of a glass substrate having substantially the same refractive index as the lower clad material;
A method for manufacturing an optical waveguide, comprising:   The step of forming the intermediate clad layer and the step of providing a void portion are formed by forming a waveguide pattern on the resin layer after forming an uncured resin layer containing a photopolymerization initiator on the upper surface side of the lower clad material. The light guide according to claim 1, wherein the mask is mounted and cured by irradiation with light, and thereafter the uncured portion is chemically removed to form an intermediate cladding layer and a hole portion. A method for manufacturing a waveguide.   The step of forming the intermediate clad layer and the step of providing the void portions are performed by forming a mold having a waveguide pattern on the transfer surface from the upper surface side after forming an uncured resin layer on the upper surface side of the lower clad material. It is inserted into an uncured resin layer by pressing, the resin layer is cured in a state where the transfer surface is in contact with the upper surface side of the lower clad material, and then the mold is opened. Item 12. A method for manufacturing an optical waveguide according to Item 1.   The step of forming the intermediate clad layer and the step of providing a void portion include forming a resin layer made of a thermoplastic resin on the upper surface side of the lower clad material, and then heating the resin layer in a softened state. The mold on which the waveguide pattern is formed is pressed from the upper surface side and inserted into the resin layer, and the resin layer is cooled and cured in a state where the transfer surface is in contact with the upper surface side of the lower clad material, 2. The method of manufacturing an optical waveguide according to claim 1, wherein the mold is opened.

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