JP4513005B2 - Method for manufacturing flexible optical waveguide - Google Patents

Description

  The present invention relates to a flexible optical waveguide, a method for manufacturing the same, and a manufacturing apparatus, and more particularly, to a flexible optical waveguide in which a transparent thin wire material serving as a core is arranged at a predetermined position and sandwiched by a transparent film serving as a cladding, and a manufacturing method and manufacturing apparatus.

  Regarding a flexible optical waveguide, Patent Document 1 shows that a polymer film optical waveguide can be produced. A polymer film is formed by spin-coating a polymer solution or the like on a substrate such as silicon and baking to form a lower clad layer. After a core layer is formed by the same method, a mask pattern is formed using a Si-containing resist or the like. After forming the core pattern by dry etching, the upper cladding layer is formed by the same method as the method of forming the lower cladding layer. Finally, the optical waveguide formed into a film is produced by peeling the optical waveguide from the substrate. In particular, a method is shown in which a thermally oxidized Si substrate is used as a substrate for easy peeling, and peeling is performed by immersing in hydrofluoric acid after forming a waveguide.

JP-A-7-239422

In the filmed optical waveguide, each layer of the lower clad, core, and upper clad is formed by spin coating and baking. Therefore, in this method, it takes time to form each layer and it is necessary to form each layer in order. Manufacturing time is several tens of hours. Further, since Si is used for the substrate, it is not suitable for manufacturing a large number of optical waveguides having a size of several centimeters to several tens of centimeters. In addition, the above manufacturing method includes a dry etching step, and in order to produce a multimode optical waveguide having a thick core layer, it is necessary to perform dry etching for a very long time.
The present invention is to provide a manufacturing how and inexpensively mass manufacturable structure large multimode flexible optical waveguide of core size.

In the present invention, [ 1 ] a transparent transparent thin film having a refractive index smaller than that of a transparent thin wire and a lower transparent clad film having a refractive index smaller than that of the transparent thin wire by arranging a plurality of transparent thin wires having a circular or nearly circular cross section as a core. The present invention relates to a method for manufacturing a flexible optical waveguide, characterized in that the transparent fine wire is sandwiched by an upper transparent clad film having a small thickness and heated and pressed so that the transparent fine wire is covered with a transparent clad material made of a transparent resin.
The present invention also provides: [ 2 ] a transparent thin wire material in which a plurality of transparent thin wire materials serving as a core are arranged on a lower transparent clad film at a predetermined interval in the longitudinal direction of the lower transparent clad film, The present invention relates to a method for manufacturing a flexible optical waveguide, which includes a step of forming a structure covered with a transparent clad material made of a transparent resin.
The present invention also provides a transparent fine wire, a lower transparent clad film, and an upper transparent clad film before the transparent fine wire is sandwiched between the lower transparent clad film and the upper transparent clad film in [ 3 ] [ 1 ] or [ 2 ]. The present invention relates to a method for manufacturing a flexible optical waveguide, wherein surface treatment is performed on at least one of the above.
Further, the present invention is [4] a surface treatment in the above-mentioned [3], a corona discharge treatment, plasma discharge treatment, solvent coating process, a flexible optical waveguide which is a one or a combination of UV irradiation treatment It relates to the manufacturing method.

  According to the flexible optical waveguide of the present invention, the core has a circular shape or a shape close to a circular shape, and it is not necessary to consider twist when forming the core in the clad. Further, since there are no corners, the stress generated at the core / cladding interface can be relaxed. The concentration of stress becomes a factor that lowers the bending resistance, and the bending resistance can be improved by using the structure of the present invention. In addition, according to the flexible optical waveguide of the present invention, the flexible optical waveguide can be formed by a structure in which the transparent thin wire materials serving as the core are arranged and the transparent thin wire material is covered with a clad material having a refractive index smaller than that of the transparent thin wire material. For this reason, a multi-mode optical waveguide having a large core size does not require a dry etching process, so that the optical waveguide can be manufactured in a short time. For example, when a multi-mode optical waveguide is manufactured on a Si wafer according to a conventional method, a lower clad, a core, and an upper clad are formed on the wafer in order, and the time required for each process for forming each of them is increased. Since it takes at least 2 to 5 hours, it took one week or more to complete the product, including peeling and cutting of the optical waveguide. On the other hand, when the present invention is used, the lower clad, core, and upper clad can be manufactured separately, and it takes 1-2 minutes from the introduction of these members until the first product is completed. That's it. In addition, even when the lower clad, core, and upper clad members are formed in the equipment, it only takes time to cure the resin, and other processes require little time. End in time. While the conventional method requires an apparatus for each process, a flexible optical waveguide can be manufactured with one manufacturing apparatus of the present invention. Also, since an Si substrate is not used when producing an optical waveguide, a film size larger than 300 mm, the largest Si wafer size, can be several centimeters to several tens of centimeters, and even longer optical waveguides if necessary. It can be manufactured in large quantities at low cost.

Embodiments of a flexible optical waveguide, a manufacturing method thereof, and a manufacturing apparatus to which the present invention is applied will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of a flexible optical waveguide according to the first embodiment of the present invention viewed from above. In FIG. 1, a transparent thin wire 1 serving as a core through which light passes is covered with a transparent clad material 2. In FIG. 1, the core has a circular cross section, but does not need to be a perfect circle. The core material and the clad material are required to be optically transparent, and in particular, the core material through which light passes is required to be a material with small light loss. The larger the refractive index difference between the core and the clad, the more the loss when the optical waveguide is bent can be suppressed. As the core material, polycarbonate resin, polystyrene resin, amorphous polyolefin resin, acrylic resin, silicone resin, A polyamide resin, a fluororesin, a polyimide resin, etc. are mentioned. Further, examples of the clad material include polyurethane resin, polyethylene resin, polypropylene resin, and elastomer resin in addition to the core material. As described above, the larger the difference in refractive index between the core and the clad, the more the loss when the optical waveguide is bent can be suppressed. Therefore, it is 1% or more, preferably 2% or more, more preferably 5% or more. Specifically, it is required to be 1 to 25%, more preferably 2 to 25%, and further preferably 5 to 25%. Here, the refractive index was measured using a prism coupler.
When the transparent thin wire material is plastic, the transparent clad material preferably has an elastic modulus of 2 GPa or less. In order for the optical waveguide to bend flexibly, the elastic modulus of both the core material and the clad material is required to be as small as 2 GPa or less (temperature in use, 0 to 30 ° C.). In particular, the elastic modulus of the clad material is 0.05. To 2 GPa, more preferably 0.05 to 1 GPa, and most preferably 0.05 to 500 MPa. These elastic moduli were obtained by a three-point bending method shown in ISO178. The elastic modulus here is a value of bending elastic modulus, and by setting it to 2 GPa or less, the elastic modulus becomes smaller than the widely used flexible printed board made of polyimide resin, and the transition from the flexible printed board is easy. can do. Further, by reducing the flexural modulus, the design tolerance of the cladding thickness is widened, the stress inside the waveguide when bent is reduced, and the reliability against peeling and the like is improved.
Although not shown in FIG. 1, it is preferable to have a structure in which either or both of the upper and lower surfaces of the flexible optical waveguide shown in FIG. 1 are covered with another material for protection, information display, and the like. . Examples of the covering material include resins having flame retardancy and high moisture resistance, metal thin films, and composites thereof. Specifically, in addition to polyvinyl chloride resin, polyethylene resin, polyester elastomer, silicone rubber, fluorine resin, olefin elastomer, santoprene, polyurethane resin, polypropylene resin, polyimide resin, polyamide resin, these resins and metals such as Al The thing which laminated | stacked the thin film can be illustrated. In this example, a 0.1 mm thick polyvinyl chloride film was used as a material for covering the surface of the flexible optical waveguide. As shown in FIG. 1, it is preferable that a plurality of transparent thin wire rods 1 are provided and adjacent transparent thin wire rods are parallel to each other.

  FIG. 2 shows a cross-sectional view of a flexible optical waveguide according to the second embodiment of the present invention as viewed from above. In the present invention, a plurality of transparent thin wires 1 serving as a core are arranged side by side in a curved state. As in FIG. 1, the cross-sectional shape is a structure in which a transparent thin wire 1 serving as a core through which light passes is sandwiched between an upper transparent cladding material and a lower transparent cladding material. The cross section of the core is circular, but need not be a perfect circle. The cross section may be a quadrangle. For the core material and the clad material, the same materials as in the first embodiment can be selected. Although not shown in FIG. 2, it is preferable to have a structure that covers either or both of the upper and lower surfaces of the flexible optical waveguide shown in FIG. Examples of the covering material include resins and metal thin films having flame retardancy and high moisture resistance as described above, and composites thereof.

  FIG. 3 shows an example of a flexible optical waveguide that is the third embodiment of the present invention. Optical elements such as a light emitting element and a light receiving element are mounted on both ends of the optical waveguide, or an optical fiber is mounted. At that time, it is required that the core of the optical waveguide, the optical element, and the optical fiber be accurately aligned and mounted. Therefore, as shown in FIG. 3, it is preferable to form an alignment mark for specifying the position of the core on the flexible optical waveguide. This alignment mark is preferably formed at a position relatively determined with respect to the position of the core. In this embodiment, the alignment mark is formed using a laser, and the alignment mark is used to accurately process the optical waveguide into a predetermined shape. The alignment mark is optically recognized, and the flexible optical waveguide is The product was cut into a shape to obtain a flexible optical waveguide as a product. As described above, the alignment mark was formed using a scanning YAG laser marker.

  The manufacturing method of the flexible optical waveguide which is 1st Embodiment using this invention was shown in FIG. A metal frame (size: outer dimension 110 × 15 mm, inner dimension 100 × 10 mm, thickness 0.15 mm) subjected to mold release treatment is placed on the PET film that has been subjected to mold release treatment (a), and becomes a core on the frame. A thin transparent material (diameter: 50 μm, made of nylon) is fixed in a stretched state (b). Although two thin transparent materials are illustrated in FIG. 4, one or more thin transparent materials may be used. Further, after placing a metal frame that has been subjected to mold release treatment (c), a transparent resin to be a clad is poured into the frame to cure the resin (d). Next, the frame was removed (e) and cut into a predetermined shape to complete the optical waveguide (f). In this case, the transparent resin to be the clad is liquid and is cured by heat or UV light. Specifically, nylon was used as the transparent thin wire material serving as the core, and thermosetting silicone rubber was used as the cladding material. Thermosetting was completed by heating at a temperature of 90 ° C. for 1 hour. In order to improve the adhesion between the core material and the clad material, a surface treatment may be performed on the core material. In this example, corona discharge was used as the surface treatment. The corona discharge treatment was performed on the core material surface with an applied voltage of 12 kV. In addition, plasma discharge treatment, solvent coating treatment, UV irradiation treatment, or the like may be used as the surface treatment. The pitch of the transparent thin wire 3 was 250 μm in accordance with the pitch of the optical element combined with the optical waveguide of the present invention.

  A second method for manufacturing a flexible optical waveguide using the present invention is shown in FIG. A release-treated metal frame is placed on the release-treated PET film (a), and a transparent resin serving as a lower clad material is poured therein to cure the resin (b). A thin transparent material serving as a core is placed on the lower clad (c). Further, after placing a metal frame that has been subjected to mold release treatment (d), a transparent resin to be a clad is poured into the frame to cure the resin (e). Next, the optical waveguide was completed by removing the frame (f) and cutting it into a predetermined shape (g). In this case, the transparent resin to be the clad is liquid and is cured by heat or UV light. Specifically, nylon was used as the transparent thin wire material serving as the core, and thermosetting silicone rubber was used as the cladding material. Thermosetting was completed by heating at a temperature of 90 ° C. for 1 hour.

  FIG. 6 shows an example of an apparatus for manufacturing a flexible optical waveguide using the present invention. The upper part of FIG. 6 shows an apparatus configuration diagram when the manufacturing apparatus is viewed from above, and the lower part of FIG. 6 is an apparatus configuration diagram when the manufacturing apparatus is viewed from the side. By using this apparatus, for example, the flexible optical waveguide shown in FIG. 3 can be manufactured. In this apparatus, the roll around which the transparent lower clad film 22 is wound and the roll around which the transparent upper clad film 23 is wound are fed so as to sandwich the transparent thin wire 1 serving as a core, and set to a predetermined temperature. It is laminated by the roller 4 and wound up on the roll 5. In this apparatus, four transparent thin wire rods 1 serving as cores are arranged, and a core position adjusting guide 6 is attached so that the transparent thin wire rods 1 are arranged at a predetermined pitch. Adjustment can be performed by the core position adjustment guide 6 based on the core position information. Further, a rough alignment core position adjustment guide 9 and a tension adjustment guide 10 are combined for core position adjustment. In accordance with the position of the wound transparent thin wire 1, the rough alignment core position adjustment guide 9 is installed slightly inclined. A core position alignment mark forming laser 8 is incorporated for forming an alignment mark, and a mark is formed at a predetermined distance from the core position based on information from the core position reader 7. Marks to be formed can form a cross mark as well as a linear pattern.

The figure which shows the structure of the flexible optical waveguide concerning the 1st Embodiment by this invention. The figure which shows the structure of the flexible optical waveguide concerning the 2nd Embodiment by this invention. The figure which shows the structure of the flexible optical waveguide concerning the 3rd Embodiment by this invention. The figure which shows the 1st manufacturing method of the flexible optical waveguide by this invention. The figure which shows the 2nd manufacturing apparatus of the flexible optical waveguide by this invention The figure which shows the manufacturing apparatus of the flexible optical waveguide by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent fine wire material used as core 2 Cladding 3 Transparent fine wire material 4 Laminating roller 5 Roll (waveguide film)
6 Core position adjustment guide (high precision alignment)
7 Core position reading device 8 Core position alignment mark writing laser 9 Core position adjustment guide (rough alignment)
10 Tension adjustment guide 11 Alignment mark 22 Lower clad film 23 Upper clad film

Claims (4)

  A plurality of transparent thin wire materials having a circular or nearly circular cross-sectional shape as the core are arranged side by side with a lower transparent clad film having a refractive index smaller than that of the transparent thin wire material and an upper transparent clad film having a refractive index smaller than that of the transparent thin wire material. A method for producing a flexible optical waveguide, characterized in that the transparent fine wire is sandwiched and heated and pressed, and the transparent fine wire is covered with a transparent clad material made of a transparent resin.   A plurality of transparent thin wires having a circular or nearly circular cross-sectional shape as a core on the lower transparent clad film are arranged at predetermined intervals in the longitudinal direction of the lower transparent clad film, and the upper transparent clad film is overlaid. A method for producing a flexible optical waveguide, comprising a step of sandwiching and forming a structure in which a transparent fine wire is covered with a transparent clad material made of a transparent resin. Characterized in that claim 1 or lower the transparent thin line material according to claim 2 transparent cladding film and an upper transparent cladding transparent thin wire material before sandwiching the film, the surface treatment at least on one of the lower transparent cladding film and upper transparent cladding film A method for producing a flexible optical waveguide. 4. The method for producing a flexible optical waveguide according to claim 3, wherein the surface treatment is any one or a combination of corona discharge treatment, plasma discharge treatment, solvent coating treatment, and UV treatment.

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