JP2005099501A - Optical waveguide constituted by joining optical waveguides together - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain a long-sized optical waveguide as to a method for manufacturing an integrated circuit, an optical component for optical interconnection, an optical and electric hybrid board, etc. <P>SOLUTION: A plurality of optical waveguide films can be obtained by cutting an optical waveguide film 1 in a desired shape with a dicing saw, etc. Ends of two optical waveguides to be joined together among them are visually and roughly positioned to abut against each other, and sandwiched between members 2 such as glass plates and plastic plates from above and below. Further, they may be positioned without using a fine moving alignment stage etc., by fitting plates, rods, etc., in a shape conforming with grooves and recesses instead of the members between which the optical waveguides are sandwiched. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polymer optical waveguide, and more particularly to a method of manufacturing an optical integrated circuit, an optical component for optical interconnection, an opto-electric hybrid board, and the like.

  As base materials for optical components or optical fibers, inorganic materials such as quartz glass and multicomponent glass, which have the characteristics of low light propagation loss and wide transmission band, are widely used. System materials have also been developed and are attracting attention as materials for optical waveguides because they are superior in processability and price compared to inorganic materials. For example, a flat plate type having a core-clad structure in which a polymer having excellent transparency such as polymethyl methacrylate (PMMA) or polystyrene is used as a core and a polymer having a refractive index lower than that of the core material is used as a cladding material. An optical waveguide is manufactured (Patent Document 1: Japanese Patent Laid-Open No. 3-188402). On the other hand, a low-loss flat optical waveguide is realized using polyimide, which is a transparent polymer with high heat resistance (Patent Document 2: Japanese Patent Laid-Open No. 2-110500).

  For optical interconnection, optical waveguides are being considered as an alternative to electrical wiring. Since a transmission distance that makes high-speed transmission difficult with electrical wiring is required with optical wiring, for example, a multi-array optical waveguide with a length of 20 cm or more is often required. However, many polymer optical waveguides are limited to the size of the substrate because they are manufactured using spin coating. Therefore, even when an attempt is made to use a large substrate such as 10 inches, non-uniformity in film thickness and processing accuracy occurs, and it is very difficult to produce an optical waveguide having a length of 20 cm or more, for example It is.

On the other hand, it is possible to produce a long optical waveguide by connecting a plurality of optical waveguides with an optical connector. However, it is difficult to manufacture an optical connector having a wide width of several centimeters or more. In addition, when there is a solder reflow process, there is a problem with the heat resistance of the connector.
Japanese Patent Laid-Open No. 3-188402 JP 2-110500 A

An object of the present invention is to provide a long optical waveguide that can be easily realized in order to avoid the above problems.

  As a result of intensive studies, the present inventor has found that the above problems can be solved by sandwiching optical waveguides from above and below with a substrate and adhesively fixing them, thereby completing the present invention. That is, the present invention is an optical waveguide having a structure in which a plurality of optical waveguides are bonded and fixed at the end faces in the respective waveguide directions.

   It is preferable to have a structure in which the bonded and fixed portion is sandwiched from above and below by a member. In this case, it is preferable that the member and the optical waveguide are also bonded and fixed.

   Furthermore, the present invention is a method for joining optical waveguides, characterized in that alignment is performed using a dent present in the optical waveguide as a guide, and a plurality of optical waveguides are joined at the end faces in the respective waveguide directions.

 By using the optical waveguide bonding method according to the present invention, a long optical waveguide can be manufactured at low cost. Also, for a wide variety of circuit patterns, a variety of optical waveguides can be easily formed by changing the circuit design of each optical waveguide to be joined and the combination of the optical waveguide film. Even in a multi-array having a plurality of optical waveguides in parallel, an optical waveguide having a required length can be obtained. Furthermore, since the material of the member of a junction part can be selected widely, heat resistance can be improved.

Hereinafter, the present invention will be described in detail. Here, a polyimide optical waveguide will be described as an example, but it is of course possible to use an optical material resin other than polyimide as a material for the optical waveguide. FIG. 1 shows an example of bonding between optical waveguides of the present invention.

  First, a lower clad layer is formed on a silicon wafer. A layer having a core part and a resist layer are sequentially formed thereon. Next, the resist pattern used as a mask is formed by exposing using the mask pattern in which the desired core pattern was drawn. Using this resist pattern as a mask, a layer whose core is partly dry is etched with oxygen plasma. Next, the resist of the mask is removed with a stripping solution. Next, an upper clad layer is formed thereon. Then, the multi-layered silicon wafer is immersed in a hydrofluoric acid aqueous solution, and the multilayer that becomes the optical waveguide is peeled off from the silicon wafer. Thus, an optical waveguide film in which the optical waveguide is formed is obtained.

  The optical waveguide film 1 thus obtained can be cut into a desired shape with a dicing saw or the like to obtain a plurality of optical waveguide films. Of these, the two optical waveguides to be joined (FIG. 1 (a)) are roughly aligned with each other so as to abut against each other, and sandwiched between members 2 such as a glass plate and a plastic plate from above and below. Various materials can be used for the member regardless of whether they are inorganic or organic, and a film may be used. The width of this member is set slightly larger than the width of the optical waveguide. When sandwiched by this member, a UV curable or thermosetting adhesive 3 is applied between the optical waveguide and the member (FIG. 1B). Thereafter, a load is applied and pressed from above the member by a spring (not shown) or the like. This completes the alignment in the film thickness direction. In the case of a multi-array, it is only necessary to observe one waveguide of the multi-array.

Next, the core pattern is observed from the upper surface of the optical waveguide, and alignment is performed using a fine adjustment center stage so that both patterns are matched.
At this time, a groove formed by a dicing saw or the like in the optical waveguide, or a recess 11 on the outermost surface of the optical waveguide formed in the extending direction of the core caused by evaporation of the solvent in the optical waveguide manufacturing process is used as a guide (FIG. 2 (a)), alignment may be performed. For example, as shown in FIG. 2 (b), a plate 12 or a rod having a shape that fits into a groove or a recess is used instead of a member that sandwiches the optical waveguide. Can be combined (FIG. 2 (c)). The plate may be adhered and fixed as it is, or may be sandwiched with another member after alignment. Thereafter, the adhesive is cured by UV irradiation or heat treatment. By sandwiching the upper and lower portions of the optical waveguide joint with the members, not only reinforcement against bending, but also adhesive strength is improved. Moreover, even if the adhesive strength between the optical waveguide and the member is slightly weak, the adhesive strength is improved by bonding the members protruding from the optical waveguide by using the optimum adhesive for bonding between the members. The strength of the part, in particular, the peel strength can be improved. In this manner, a long optical waveguide in which the optical waveguides are joined can be manufactured without using an optical connector.

  Subsequently, the present invention will be described in more detail using several examples. It is apparent that an unlimited number of polymer optical waveguides of the present invention can be obtained by using various polymer solutions having different molecular structures. Therefore, the present invention is not limited only to these examples.

(Example 1)
2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFDB) on a 5-inch silicon wafer An optical waveguide film is formed by known photolithography and dry etching techniques using polyimide formed from) as upper and lower cladding layers and polyimide formed from 6FDA and 4,4′-oxydianiline (ODA) as a core layer. To do. Here, a plurality of core layers whose length directions are parallel to each other are formed to form a multi-array optical waveguide. Thereafter, the silicon wafer on which the optical waveguide was formed was immersed in a 5 wt% hydrofluoric acid aqueous solution, and the optical waveguide was peeled off from the silicon wafer to produce a film optical waveguide. The thickness of the film waveguide was 80 μm. The variation in thickness between the optical waveguide samples was within 2 μm. The optical waveguide was cut out with a dicing saw so as to have a length of 10 cm and a width of 5 cm. An optical waveguide having a length of 20 cm is produced using the two optical waveguides thus obtained.

   Two optical waveguides were placed on a glass plate having a thickness of 1 mm, and aligned roughly so that the core pattern was visually matched. At that time, a UV curable adhesive is applied between the two film optical waveguides and the glass. Next, a UV curable adhesive was similarly applied from above, another glass plate having a thickness of 1 mm was placed, and lightly pressed. Then, the fine adjustment center stage was moved so that the core pattern might be matched with the optical microscope from above, and alignment was performed. At this time, one set of core patterns may be observed and aligned. From above the upper glass plate, the vicinity of the center was pressed with a spring. With a spot type UV irradiator, UV was irradiated from above and below to cure the adhesive. At this time, the coupling loss of the junction was about 0.5 dB. In this manner, an optical waveguide having a length of 20 cm and a width of 5 cm could be easily produced with low coupling loss.

(Example 2)
An optical waveguide was produced using the same fluorinated polyimide as in Example 1. A plurality of grooves were formed in the lower clad by photolithography and dry etching techniques. The groove was filled with fluorinated polyimide as a core and heat-treated. Thereafter, an upper clad was applied from above and heat-treated. At this time, a recess formed by evaporation of the solvent was formed in the groove. It was a depression on an arc having a depth of 20 μm and a width of 40 μm. A polyimide film with a convex shape to be fitted with this was separately produced by photolithography and dry etching techniques. This polyimide film was cut into a length of 1 cm and a width of 6 cm. The produced optical waveguide was cut out with a dicing saw to a length of 10 cm and a width of 5 cm.

  The two optical waveguides thus obtained were placed on a polyimide substrate placed on a hot plate and coated with a thermosetting adhesive. Next, a polyimide film with a convex shape thinly coated with an adhesive was placed from above and fitted into the recesses of the two optical waveguides. At this time, the entire polyimide film was pressed from above using a spring. Thereafter, the temperature of the hot plate was raised, and heat treatment was performed at 150 ° C./1 hour to fix the adhesive. At this time, the coupling loss of the junction was about 0.7 dB. In this manner, an optical waveguide having a length of 20 cm and a width of 5 cm could be easily produced with low coupling loss.

  In particular, an optical waveguide used for an optical integrated circuit, an optical component for optical interconnection, an opto-electric hybrid board and the like can be provided.

It is a figure which shows an example of the optical coupling method of optical waveguides by this invention. It is a figure which shows an example of the optical coupling method of the optical waveguides using a fitting structure by this invention.

Explanation of symbols

1: optical waveguide, 2: member, 3: adhesive
11: a dent formed in the optical waveguide,
12: A plate with a convex shape for fitting into the recess.

Claims (3)

   An optical waveguide characterized in that a plurality of optical waveguides are bonded and fixed to each other at end faces in the respective waveguide directions.    The optical waveguide according to claim 1, wherein the bonded and fixed portion is sandwiched from above and below by a member.    A method for joining optical waveguides, wherein alignment is performed using a dent existing in the optical waveguide as a guide, and the plurality of optical waveguides are joined to each other at end faces in the respective waveguide directions.

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