JP2008102296A - Long-length optical waveguide and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-length optical waveguide that can easily be manufactured, and also to provide its manufacturing method. <P>SOLUTION: On the surface of an underclad layer, a core layer 3 is formed in a non-linear belt-like pattern such as a meandering shape having bends, with an over-clad layer formed in a manner enclosing the core layer. A three-layered structure so shaped is formed in an optical waveguide A having a profile along the non-linear belt-like pattern of the core layer 3. Then, by pulling both ends of the optical waveguide A in directions opposite to each other, the optical waveguide A of the meandering shape for example is stretched and formed into a long shape. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a long optical waveguide widely used in optical communication, optical information processing, and other general optics, and a method for manufacturing the same.

  An optical waveguide is incorporated in an optical device such as an optical waveguide device, an optical integrated circuit, or an optical wiring board, and is widely used in the fields of optical communication, optical information processing, and other general optics. Examples of the optical waveguide include a three-layer structure in which a core layer is formed in a predetermined pattern on an under cladding layer, and an over cladding layer is formed so as to include the core layer. The pattern formation of the core layer is performed by a photolithography process (see, for example, Patent Document 1).

Recently, with the development of optical communication, information communication between optical devices such as optical wiring boards is shifting from metal cables to optical interconnections using optical waveguides. Correspondingly, a long optical waveguide is required.
Japanese Patent Laid-Open No. 2005-266739

  As described above, the production of the optical waveguide requires a photolithography process, and the exposure area of the exposure apparatus used in the photolithography process is usually about 250 mm × 250 mm. For this reason, in order to produce an optical waveguide having a length exceeding the area, it is necessary to divide the exposure into a plurality of times. However, in this case, it is difficult to manage the exposure between adjacent exposure areas (connecting portions), and the positional deviation is likely to occur. Due to the positional deviation, a part where the exposure overlaps or a part where the exposure is not performed occurs. There is a risk of disconnection in the optical waveguide.

  Although it is conceivable to use an exposure apparatus with a long exposure area, the area where uniform exposure is possible is the above-mentioned area, and it is practically cost effective to newly develop an exposure apparatus with a long exposure area. is not. In addition, it is possible to make a plurality of optical waveguides having a short path length by using the normal exposure area, and to obtain an optical waveguide having a long path length by connecting them. There is a drawback of becoming longer.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a long optical waveguide that can be easily manufactured and a manufacturing method thereof.

  In order to achieve the above object, the present invention provides an optical waveguide having a long path length formed in a non-linear belt-like pattern having a bent portion such as a meandering shape, wherein the bent portion in the meandering shape is folded. The first gist of the present invention is a long optical waveguide that is formed so that a non-linear strip-shaped optical waveguide such as a meandering shape can be formed in a substantially straight line by being bent using this folding margin.

  The present invention also includes a step of forming an undercladding layer, a step of forming a core layer on the surface of the undercladding layer in a non-linear strip pattern having a bent portion such as a meandering shape, and the core layer. And forming a three-layer structure including the under cladding layer, the core layer, and the over cladding layer into an optical waveguide having a shape along the non-linear strip pattern of the core layer. And a method for producing a long optical waveguide, comprising: stretching the both ends of the optical waveguide in opposite directions to stretch the shape of a meandering shape, etc. Is the second gist.

  The long optical waveguide of the present invention forms a bent portion or the like in a meandering shape at a folding margin, and bends using the folding margin to make a non-linear belt-like optical waveguide such as a meandering shape substantially linear. Since it can be formed, it is easy to make the path length longer than the exposure area. That is, according to the present invention, a pattern having a bent portion, such as a meandering shape, is formed without difficulty in an exposure area of the exposure apparatus, and then the length of the path is reduced by a simple process of stretching the shape of the meandering shape. A long optical waveguide can be obtained. For this reason, a connection part (connector) and a complicated connection operation become unnecessary. Moreover, since there is no connection part (connector) in the optical waveguide with a long path length, the obstacle (disconnection etc.) by the connection part (connector) does not arise.

  According to the method for producing a long optical waveguide of the present invention, an optical waveguide having a long path length as described above can be simply obtained by pulling both ends of an optical waveguide having a bent portion, such as a meandering shape, in opposite directions. It can be obtained by a process. For this reason, a long optical waveguide longer than the exposure area can be easily manufactured.

  In particular, when the non-linear band-shaped pattern of the core layer is a folded shape having one or more U-shaped bent portions, the optical waveguide is formed more effectively in a limited exposure area. Therefore, the length of the optical waveguide can be increased more easily.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIGS. 1-7 shows 1st Embodiment of the manufacturing method of the elongate optical waveguide of this invention, FIG. 7 shows 1st implementation of the elongate optical waveguide of this invention obtained by the manufacturing method among them. The form of is shown. In the long optical waveguide of this embodiment, as shown in FIG. 7, adjacent strip-shaped optical waveguides 10 are continuous at the side portions (bent portions 11 described later) of the respective one end portions, and the bent portions 11 thereof. In this embodiment, four strip-shaped optical waveguides 10 are continuous.

  The method for producing the long optical waveguide will be described in more detail.

  First, the base film 1 (refer FIG. 1) used as the foundation which manufactures the said optical waveguide is prepared. The material for forming the base film 1 is not particularly limited, and examples thereof include PEN (polyethylene naphthalate), PET (polyethylene terephthalate), and SUS (stainless steel). The dimension of the base film 1 is preferably about 250 mm × 250 mm from the viewpoint of approaching the exposure area (about 250 mm × 250 mm), and the thickness is not particularly limited, but the forming material is usually made of PEN or PET. In this case, it is about 180 μm, and when the forming material is SUS, it is about 20 μm.

Next, as shown in FIG. 1, an under cladding layer 2 is formed on the surface of the base film 1. Examples of the material for forming the under cladding layer 2 include polyimide resin, epoxy resin, photopolymerizable resin, and photosensitive resin. A method for forming the under cladding layer 2 is not particularly limited. For example, the under cladding layer 2 is formed by applying a varnish in which the resin is dissolved in a solvent and then curing the varnish. The varnish is applied by, for example, a spin coating method, a dipping method, a casting method, an injection method, an ink jet method, or the like. Moreover, the said hardening is suitably performed with the formation material, thickness, etc. of the under clad layer 2, for example, when the under clad layer 2 consists of polyimide resins, it is performed by the heat processing of 300-400 degreeC x 60-180 minutes. When the undercladding layer 2 is made of a photopolymerizable resin, it is performed by heat treatment at 80 to 120 ° C. for 10 to 30 minutes after irradiation with ultraviolet rays of 1000 to 5000 mJ / cm ² . The thickness of the under cladding layer 2 is usually set to 5 to 50 μm in the case of a multimode optical waveguide, and is set to 1 to 20 μm in the case of a single mode optical waveguide.

  Next, as shown in FIG. 2, a resin layer 3a to be a core layer 3 (see FIGS. 3A and 3B) is formed on the surface of the under cladding layer 2 later. As a material for forming the resin layer 3a, a photopolymerizable resin is usually used, which has a refractive index higher than that of the material for forming the under cladding layer 2 and the following over cladding layer 4 (see FIGS. 4A and 4B). Is a big material. The formation of the resin layer 3a is not particularly limited. For example, the resin layer 3a is formed by applying a varnish in which a photopolymerizable resin is dissolved in a solvent on the under cladding layer 2 and then drying the varnish. . The varnish is applied in the same manner as described above, for example, by spin coating, dipping, casting, injection, ink jet, or the like. Moreover, the said drying is performed by 50-120 degreeC x 10-30 minutes heat processing.

Then, the resin layer 3a is exposed with an irradiation line L through a photomask M in which an opening pattern corresponding to a desired core layer 3 [see FIGS. 3 (a) and 3 (b)] pattern is formed. In this embodiment, as shown in FIG. 3B, the core layer 3 pattern is formed so that each core layer 3 is substantially W-shaped (a folded shape having three U-shaped bent portions 11). In addition, a plurality of substantially W-shaped core layers 3 are formed side by side. Examples of the exposure method include projection exposure, proximity exposure, contact exposure, and the like. When the resin layer 3a is not sticky, a contact exposure method in which the photomask M is brought into contact with the resin layer 3a is preferably used. This is because the workability is improved and the latent image can be surely formed. Further, as the irradiation line L for exposure, for example, visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, γ-rays and the like are used. Preferably, ultraviolet rays are used. This is because when ultraviolet rays are used, a large curing rate can be obtained by irradiating large energy, and the irradiation device is also small and inexpensive, and the production cost can be reduced. Examples of the ultraviolet light source, for example, low pressure mercury lamp, high pressure mercury lamp, ultra-high pressure mercury lamp and the like, the dose of ultraviolet radiation is typically, 10 to 10000 mJ / cm ^2, preferably from 50 to 3000 mJ / cm ^2.

  After the exposure, heat treatment is performed to complete the photoreaction. This heat treatment is performed at 80 to 250 ° C., preferably 100 to 200 ° C., for 10 seconds to 2 hours, preferably 5 minutes to 1 hour. Then, by developing using a developing solution, as shown to FIG. 3 (a), (b), the unexposed part in the resin layer 3a is dissolved and removed, and the resin layer 3a is pattern-formed. Then, the developer in the patterned resin layer 3a is removed by heat treatment to form the core layer 3. This heat treatment is usually performed at 80 to 120 ° C. for 10 to 30 minutes. The thickness of the core layer 3 is usually set to 20 to 100 μm in the case of a multimode optical waveguide, and is set to 2 to 10 μm in the case of a single mode optical waveguide. For the development, for example, an immersion method, a spray method, a paddle method, or the like is used. As the developer, for example, an organic solvent, an organic solvent containing an alkaline aqueous solution, or the like is used. Such a developer and development conditions are appropriately selected depending on the composition of the photopolymerizable resin composition.

  In this way, as shown in FIG. 3B, a plurality of substantially W-shaped core layers 3 are formed side by side. Further, as shown in FIG. 3A, each of the substantially W-shaped core layers 3 is formed with one or a plurality of strip-shaped cores 30 in parallel in a substantially W-shape. In (b), the cores 30 are collectively shown as one.

  Next, as shown in FIGS. 4A and 4B, the over clad layer 4 is formed so as to include the core layer 3 (core 30). Examples of the material for forming the over clad layer 4 include the same materials as those for the under clad layer 2. The material for forming the over cladding layer 4 may be the same as or different from the material for forming the under cladding layer 2. The method for forming the over cladding layer 4 is performed in the same manner as the method for forming the under cladding layer 2. The thickness of the over clad layer 4 is usually set to 5 to 100 μm in the case of a multimode optical waveguide, and is set to 1 to 20 μm in the case of a single mode optical waveguide. In this way, as shown in FIG. 4B, a plurality of optical waveguide planned portions (portions along the substantially W-shaped core layers 3) are formed side by side.

Next, as shown in FIG. 5A, each of the optical waveguide planned portions is cut along with the substantially W shape of the core layer 3 together with the base film 1 by punching using a mold. Thereby, a substantially W-shaped (a folded shape having three U-shaped bent portions 11) of the optical waveguide A is obtained in a state where it is adhered to the surface of the substantially W-shaped base film 1. The dimensions of the substantially W-shaped optical waveguide A are, for example, the total length L ₁ : 220 mm, the total width W ₁ : 8.3 mm, and the width W _{2 of} the strip-shaped optical waveguide 10 that forms a substantially W-shape: 2 mm. The gap D of the strip-shaped optical waveguide 10 is set to 0.1 mm, and the length L _{2 of} the U-shaped bent portion 11 (folded portion) is set to 3 mm. Further, for example, as shown in FIG. 5B, four strip-shaped cores 30 are formed in each core layer 3, and the cross-sectional dimension of each core 30 is set to 50 μm × 50 μm. The thickness of the under cladding layer 2 is set to 25 μm, and the thickness of the over cladding layer 4 (thickness on the core layer 3) is also set to 25 μm.

  Then, as shown in FIG. 6, when the both ends of the substantially W-shaped optical waveguide A are pulled in opposite directions (in the direction of the arrow X shown in FIG. 6), the substantially W-shaped optical waveguide A is As shown in FIG. 7, it is stretched to be long and a long optical waveguide can be obtained. The length of the long optical waveguide is longer (for example, 300 mm or more) than the exposure area (about 250 mm × 250 mm). In FIGS. 6 and 7, the side surfaces of each layer such as the base film 1 and the under cladding layer 2 are omitted.

  In the second embodiment of the method for producing a long optical waveguide of the present invention, the base film 1 is removed from the under cladding layer 2 prior to cutting by punching using a mold in the first embodiment. It is the manufacturing method which peels. In this manufacturing method, the base film 1 and the under clad layer 2 are easily peeled off by pulling the base film 1 and the over clad layer 4 by air adsorption because the adhesive force is weak from the forming material. Can do. This manufacturing method is effective when the long optical waveguide is used as a more flexible one.

  8 and 9 show a third embodiment of the method for manufacturing a long optical waveguide of the present invention. In this embodiment, after peeling the base film 1 from the under-cladding layer 2 in the second embodiment, as shown in FIG. 8, both end edges along the lateral direction in which the optical waveguide planned portions are arranged This is a manufacturing method in which a reinforcing tape T is applied to one side or both sides of a part and then cut by punching using a mold. In this manufacturing method, examples of the reinforcing tape T include polyethylene tape and polyester tape. In this manufacturing method, as shown in FIG. 9, the reinforcing tape T is positioned at three U-shaped bent portions 11 (folded portions) and both end portions of the substantially W-shaped optical waveguide A, In a state where the substantially W-shaped optical waveguide A is elongated (see FIG. 7), resistance to stress applied to the inside of the U-shaped bent portion 11 can be obtained.

  10 and 11 show a fourth embodiment of the method for manufacturing a long optical waveguide of the present invention. In this embodiment, in the first embodiment, the base film 1 is made of SUS, and as shown in FIG. 10, the under cladding layer 2 and the over cladding layer 4 are patterned in a substantially W shape. (However, in the fourth embodiment, the adjacent underclad layers 2 and overclad layers 4 of the planned optical waveguides adjacent to each other are connected). When the under clad layer 2 and the over clad layer 4 are patterned in this way, a photopolymerizable resin or a photosensitive resin is used as a forming material thereof, and after applying each forming material, a desired opening pattern is formed. Patterning is performed by exposure with irradiation rays through the photomask formed. Prior to the cutting of the adjacent optical waveguide predecessors, as shown in FIG. 11, the SUS bases corresponding to the three U-shaped bent portions 11 and both end portions of the substantially W-shaped optical waveguide A are provided. The remaining SUS base film portion is removed by etching, leaving the material film portion. In this manufacturing method, the remaining SUS base film portion exhibits the same operations and effects as the reinforcing tape T (see FIG. 9) in the third embodiment.

  In the fifth embodiment of the method for producing a long optical waveguide of the present invention, the under-cladding layers 2 and the over-cladding layers 4 of the optical waveguide adjacent portions adjacent to each other are not connected in the second embodiment. In this way, the under-cladding layer 2 and the over-cladding layer 4 are patterned in a substantially W shape. In this manufacturing method, since the substantially W-shaped optical waveguide A is obtained when the base film 1 is peeled off, a cutting step such as punching using a mold can be made unnecessary.

  In each of the above embodiments, the inner portion of the three U-shaped bent portions 11 (folded portions) of the substantially W-shaped optical waveguide A is, for example, shown in FIG. As shown, it may be formed in a rounded shape.

  In each of the above embodiments, the optical waveguide A has a substantially W shape having three U-shaped bent portions 11 (folded portions). However, the present invention is not limited to this. It may be substantially V-shaped with one bent portion 11, may be substantially N-shaped with two U-shaped bent portions 11, or meanders with four U-shaped bent portions 11. Shape may be sufficient.

  Furthermore, if the shape of the optical waveguide is a non-linear strip-like pattern having a bent portion, the bent portion may not be U-shaped, and may be formed in a spiral shape, for example. When formed in this spiral shape, the spiral shape may be circular (bending portions are continuous), or may be a triangular shape or more (corner portions are bending portions).

  In each of the above embodiments, the base film 1 is used as a base for manufacturing the optical waveguide A. However, in each of the second, third, and fifth embodiments, the base film 1 is underclad. It is not necessary to cut or etch the base film 1 after peeling off from the layer 2, and instead of the base film 1, plate-like base materials such as blue plate glass, synthetic quartz, silicon wafer, silicon wafer with silicon dioxide, etc. May be used.

  Next, examples will be described. However, the present invention is not limited to this.

[Formation material of under clad layer and over clad layer]
35 parts by weight of bisphenoxyethanol fluorenediglycidyl ether (component A) represented by the following general formula (1), 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate (which is an alicyclic epoxy) Daicel Chemical Industries, Celoxide 2021P) (Component B) 40 parts by weight, cycloaliphatic epoxy resin having a cyclohexene oxide skeleton (Daicel Chemical Industries, Celoxide 2081) (Component C) 25 parts by weight, 4,4-bis [di (Β-Hydroxyethoxy) phenylsulfinio] phenylsulfide-bis-hexafluoroantimonate in 50% propion carbonate solution was mixed with 2 parts by weight to prepare materials for forming the undercladding layer and the overcladding layer.

[Material for forming the core layer]
By dissolving 70 parts by weight of the above component A, 30 parts by weight of 1,3,3-tris (4- (2- (3-oxetanyl) butoxyphenyl) butane, and 1 part by weight of the above component B in ethyl lactate. A material for forming the core layer was prepared.

[Production of long optical waveguide]
A long optical waveguide was produced in the same manner as in the fourth embodiment (see FIGS. 10 and 11). That is, after applying the formation material of the said under clad layer on the surface of the base film made of SUS [250 mm × 250 mm × 20 μm (thickness)] by a spin coat method, it passes through a photomask in which a desired opening pattern is formed. Then, exposure by ultraviolet irradiation at 2000 mJ / cm ² was performed. Subsequently, an under clad layer was formed by performing heat treatment at 100 ° C. for 15 minutes. The thickness of the under cladding layer was 25 μm as measured with a contact-type film thickness meter. Further, the refractive index of this under cladding layer at a wavelength of 830 nm was 1.542.

Then, a core layer forming material was applied to the surface of the under cladding layer by a spin coating method, followed by drying at 100 ° C. for 15 minutes. Next, a synthetic quartz-based chromium mask (photomask) having a substantially W-shaped pattern formed thereon is disposed above, and exposure is performed by ultraviolet irradiation at 4000 mJ / cm ² by contact exposure from above. It was. Further, a heat treatment was performed at 120 ° C. for 15 minutes. Next, by developing with an aqueous γ-butyrolactone solution, the unexposed portion was dissolved and removed, and then a heat treatment at 120 ° C. for 30 minutes was performed to form a substantially W-shaped core layer [FIG. (See (b)). Four cores were formed in this core layer (see FIG. 5B), and the cross-sectional dimensions of each core were 50 μm width × 50 μm height as measured by SEM. Further, the refractive index of the core layer at a wavelength of 830 nm was 1.602.

Next, the over clad layer forming material is applied by spin coating so as to include each core of the core layer, and then an ultraviolet ray of 2000 mJ / cm ² is passed through a photomask on which a desired opening pattern is formed. Exposure by irradiation was performed. Subsequently, an over clad layer was formed by heat treatment at 150 ° C. for 60 minutes (see FIG. 10). The thickness of the over clad layer was 25 μm when measured with a contact-type film thickness meter. Further, the refractive index of the over cladding layer at a wavelength of 830 nm was 1.542.

  Then, the SUS base film portions corresponding to the three U-shaped bent portions and both end portions of the substantially W-shaped optical waveguide are masked with a photoresist, and the other SUS base film portions. Was removed by etching (see FIG. 11).

  The dimensions of the substantially W-shaped optical waveguide (see FIG. 5A) are 220 mm in total length, 8.3 mm in total width, 2 mm in width of the strip-shaped optical waveguide, 0.1 mm in gap between adjacent strip-shaped optical waveguides, U-shaped The length of the bent portion (folded portion) was 3 mm.

  And the elongate optical waveguide was able to be obtained by pulling the both ends of the said substantially W-shaped optical waveguide to a mutually reverse direction (refer FIG. 7).

It is sectional drawing which shows 1st Embodiment of the manufacturing method of the elongate optical waveguide of this invention. It is sectional drawing which shows the manufacturing method of the said elongate optical waveguide. The manufacturing method of the said elongate optical waveguide is shown, (a) is the sectional drawing, (b) is the top view. The manufacturing method of the said elongate optical waveguide is shown, (a) is the sectional drawing, (b) is the top view. The manufacturing method of the said elongate optical waveguide is shown, (a) is the top view, (b) is the one part enlarged view. It is a perspective view which shows the manufacturing method of the said elongate optical waveguide. It is a perspective view which shows the elongate optical waveguide obtained by the manufacturing method of the said elongate optical waveguide. It is a top view which shows 3rd Embodiment of the said elongate optical waveguide. It is a top view which shows the elongate optical waveguide obtained by the said 3rd Embodiment. It is a top view which shows 4th Embodiment of the said elongate optical waveguide. It is a top view which shows the elongate optical waveguide obtained by the said 4th Embodiment. It is a top view which shows the modification of the said elongate optical waveguide.

Explanation of symbols

A Optical waveguide 3 Core layer

Claims (5)

  An optical waveguide having a long path length formed in a non-linear belt-like pattern having a bent portion such as a meandering shape, wherein the bent portion in a meandering shape or the like is formed as a folding margin, and this folding margin is utilized. A long optical waveguide characterized in that a non-linear strip-shaped optical waveguide such as a meandering shape can be formed in a substantially linear shape by bending.   The long optical waveguide according to claim 1, wherein a path length of a non-linear belt-like pattern having a bent portion such as a meandering shape is 300 mm or more.   The long optical waveguide according to claim 1 or 2, wherein the size of the entire band-shaped pattern before folding is within a square area of 250 mm x 250 mm.   Forming an undercladding layer; forming a core layer on the surface of the undercladding layer in a non-linear band pattern having a bent portion such as a meandering shape; and overcoating to include the core layer. A step of forming a clad layer, a step of forming a three-layer structure comprising the under clad layer, the core layer, and the over clad layer in an optical waveguide having a shape along the non-linear strip pattern of the core layer; A method for producing a long optical waveguide, comprising: stretching the shape of a meandering shape by pulling both ends of the optical waveguide in opposite directions to form the optical waveguide in a long shape.   5. The method for producing a long optical waveguide according to claim 4, wherein the non-linear strip pattern of the core layer has a folded shape having one or more U-shaped bent portions.

Images