JP2007127707A - Method for manufacturing optical circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing optical circuit capable of easily manufacturing an optical circuit 22 at a low cost. <P>SOLUTION: A bar-shaped preform 18 having the same cross-sectional shape is formed by adhering a core member 12 formed into a predetermined shape, clad members 14a to 14c and a protective member 16 to one another. The preform 18 is stretched in the longitudinal direction at a desired extension magnification, thereby obtaining a stretched body 20 having a cross-section substantially similar to the cross-section of the preform 18. The optical circuit 22 of a desired thickness is obtained by cutting the stretched body 20 with a face perpendicular to the stretching direction. An optical waveguide 23d having the optical circuit 22 is substantially similar to the core member 12 before stretching. Upon the formation of the preform 18, by using the core member 12 formed into a desired cross-sectional shape, the optical circuit 22 having a desired optical waveguide 24 can be formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical circuit manufacturing method.

  With the recent spread of personal computers and the Internet, information transmission demand is rapidly increasing. For this reason, it is desired to spread optical transmission having a high transmission speed to an end information processing apparatus such as a personal computer. In order to realize this, it is necessary to manufacture a high-performance optical circuit at low cost and in large quantities for optical interconnection.

  In recent years, plastics have been studied as optical circuit materials in addition to quartz-based materials. At present, plastics are inferior to quartz in terms of transmission performance and reliability, but have the advantage of being easier to mold than quartz. In addition, it has excellent light transmission performance in the wavelength range from 650 nm to 850 nm, which is a very promising optical circuit material. As a plastic optical circuit material, for example, polymethyl methacrylate (PMMA) having excellent transparency is known. In recent years, deuteration and fluorination have been carried out based on acrylic, epoxy, or polyimide resin materials. The resin material obtained thereby has low absorption with respect to light in the wavelength region of 1.3 μm or more and 1.55 μm or less. Therefore, an optical circuit with excellent transmission characteristics can be easily manufactured using these materials.

As a method for manufacturing a plastic optical circuit, an RIE method in which a core layer and a lower clad layer are applied and then an upper clad portion is formed by reactive ion etching (see, for example, Patent Documents 1 and 2), photosensitive A photolithography method in which an ultraviolet curable resin containing a material is exposed to ultraviolet rays to form a core (see, for example, Patent Document 3), and a method of forming a core by molding a core material using a mold (For example, refer patent document 4) etc. are proposed.
JP 2000-98155 A JP 2002-71989 JP-A-2005-62364 JP 2004-109926 A

  However, since the manufacturing process is complicated in the RIE method, the manufacturing cost of the optical circuit increases. In addition, since the photolithography method uses an ultraviolet curable resin as a core material, certain restrictions are imposed on the selection of the core forming material. Furthermore, in the manufacturing method disclosed in Patent Document 4, it is difficult to accurately form the shape of the core. At present, the practical methods excellent in performance are only the RIE method and the photolithography method, but neither method is sufficient as an easy and inexpensive method for manufacturing an optical circuit.

  In view of the above problems, an object of the present invention is to provide an easy and simple method for manufacturing an optical circuit.

  The optical circuit manufacturing method of the present invention includes a light incident part for inputting external light to a side surface, a light emitting part for outputting internal light from the light incident part, and an optical waveguide for connecting the light incident part and the light emitting part. A first step of forming a rod-shaped preform having the same cross-sectional shape by combining a plastic core member having a plastic and a plastic clad member disposed on a side surface of the core portion; A second step of heat-stretching in the longitudinal direction to form a stretched body having a cross section substantially similar to the cross section of the preform, and slicing the stretched body in a direction crossing the stretching direction; And a third step of obtaining a flake consisting of

  Furthermore, it is preferable that the method for manufacturing an optical circuit of the present invention includes a fourth step of laminating sub thin pieces on both surfaces of the thin piece, and it is preferable to use a sub thin piece made of the same material as the clad member. Or it is preferable to have a 5th process which forms the several thin piece which changed the shape of the core member, and laminate | stacks so that a part of core member of these thin pieces may be connected.

  It is preferable that the clad member includes an electrode portion having conductivity, and the core member is formed of a material whose optical characteristics change according to an applied voltage between the electrode portions. Moreover, it is preferable that an optical characteristic is either a refractive index, a light absorption rate, or a light scattering rate.

  The protective layer is preferably disposed on the side surface of the clad member.

  The flakes preferably include at least one light incident part and one light outgoing part.

  As a preform forming method that is a precursor of such an optical circuit, it is preferable to fix the clad member to the core member so as to expose the light incident portion and the light emitting portion of the core member. Furthermore, it is preferable that the protective member is fixed to the side surface of the clad member of the fixed body.

  A clad member provided with a core layer having a higher refractive index than that of the clad member in the vicinity of the center of the cross section may be used as a preform. Similarly, a core member having a clad layer having a refractive index lower than that of the core member on the peripheral surface may be used as a preform. You may form these core layers and clad layers by modification | denaturation (adjustment of the refractive index in each member shaping | molding process) of the predetermined part of a clad member or a core member.

  Further, in the formation of a preform which is a precursor of an optical circuit with a protective layer, it is preferable to use a protective member having a cladding layer on the peripheral surface, and the cladding layer can be formed by a modification treatment of the peripheral surface of the protective member. preferable. Similarly, it is also possible to use a clad member provided with a protective layer on the peripheral surface, and it is preferable to form the protective layer by a modification treatment of the peripheral surface of the clad member.

  It is also possible to heat-stretch an assembly formed by adhering the above-described plural types of preforms, core members, clad members, and protective members.

  It is preferable that the draw ratio of the preform is 2 to 100 million times. Moreover, it is preferable that the heating temperature of the preform is 80 ° C. or more and 500 ° C. or less. Furthermore, it is preferable to cut the stretched body along a plane perpendicular to the stretching direction.

  It is preferable that the optical waveguide connecting the light incident portion and the light emitting portion is formed in any shape of a straight line, a curve, or a combination of a straight line and a curve.

  According to the method for manufacturing an optical circuit of the present invention, a light incident part for inputting external light to a side surface, a light emitting part for outputting internal light from the light incident part, and connecting the light incident part and the light emitting part are connected. A first step of molding a rod-shaped preform having the same cross-sectional shape by combining a plastic core member having an optical waveguide and a plastic clad member disposed on a side surface of the core member; A second step of heating and stretching the preform in the longitudinal direction to form a stretched body having a cross section substantially similar to the cross section of the preform; and slicing the stretched body in a direction intersecting the stretching direction; Since it has the 3rd process of obtaining the thin piece which consists of a core member and the said clad member, mass production of an optical circuit is attained and an inexpensive optical circuit can be manufactured easily.

  In this preform heating and stretching step, voids generated on the fixing surface of the core member, clad member or protective member constituting the preform can be contracted and extinguished by stretching the void portion while reducing the pressure. It is not necessary to fix each member so that it does not occur. In addition, even if each member having a hollow portion and a gap is used on the same principle, the hollow portion and the gap can be contracted and extinguished by this heating and stretching step, so that an optical circuit having a stable quality can be manufactured. Is possible.

  Moreover, it is good also considering the laminated body obtained from the 4th process which laminates | stacks a subthin piece on both surfaces of a thin piece as an optical circuit. When the sub-thin piece made of the same material as that of the clad member is used, the numerical aperture of the optical waveguide of the laminated body is improved and transmission loss is reduced. Furthermore, since it has the 5th process which forms the several thin piece which changed the shape of the core member, and laminate | stacks so that a part of core member of these thin pieces may be connected, not only the surface direction of a laminated body but thickness direction It is also possible to manufacture an optical circuit having an optical waveguide.

  Since the clad member has a conductive electrode part and the core member is formed from a material whose optical characteristics change according to the applied voltage between the electrode parts, an optical circuit having the electrode part can be manufactured. . Since the optical characteristics (refractive index, light absorption rate, light scattering rate, etc.) of the core member change depending on the voltage applied between the electrode parts, it is possible to manufacture a voltage-controlled optical circuit with a switching function. is there.

  Since the protective layer is disposed on the side surface of the clad member, an optical circuit with the protective layer can be manufactured.

  Since the thin piece includes at least one light incident part and one light outgoing part, an optical circuit having a branch point or a coupling point can be manufactured. In addition, since the optical waveguide connecting these light incident part and light emitting part can be formed in any shape of straight line, curved line, or a combination of straight line and curved line, the optical waveguide has a shape corresponding to any optical input / output device. Can be manufactured.

  As a method of forming such a preform, a cladding member is fixed to the core member so as to expose the light incident part and the light emitting part of the core member, or on the cladding member exposing surface of the fixed body. For example, the protective member is fixed, and these methods facilitate the formation of the preform. In addition, each member forming the fixed body can be formed into a desired shape by injection molding or the like. By using each member, an optical circuit having an optical waveguide having a desired shape can be easily obtained. Can be manufactured.

  In addition to the above-described method of combining the core member, the clad member, and the protective member, a clad member having a core layer or a core member having a clad layer may be used as a preform. It is possible to form a clad layer or a core layer having a desired refractive index by appropriately selecting the addition conditions of the refractive index additive of the core member or the clad member or the conditions of heating and stretching. The same applies to the case of forming an optical circuit with a protective layer, and a preform may be formed by combining a clad member having a protective layer or a protective member having a clad layer with a core member. A clad member having a protective layer can be formed by adding a material that improves elasticity, a flame retardant, a pigment, or the like to the clad member. Similarly, a protective member having a cladding layer can be formed by adding a refractive index additive to the protective layer.

  Since the aggregate formed by fixing a plurality of preforms, core members, clad members, and protective members to each other is heated and stretched, the cross-sectional shape of the preform can be formed into a desired shape. That is, by using the present invention, an optical circuit having an optical waveguide having a desired shape and a desired dimension can be formed.

  Since the stretching ratio of the preform is 2 times or more and 100 million times or less, an optical circuit having a desired dimension can be manufactured.

  Since the core member, the clad member, and the protective member are formed of a material containing plastic, workability in the preform forming process, the stretched body forming process, and the cutting process can be improved. Since the heating temperature of the preform is 80 ° C. or more and 500 ° C. or less, the choice of the preform forming material is increased. Thus, since the choice of the material used as the composition of the preform is high, an optical circuit suitable for various usage environment conditions can be manufactured.

  The optical circuit manufacturing process 10 which is 1st Embodiment of this invention is demonstrated using FIG. First, the core member 12 is obtained in the core member production process 11, the clad member 14 is obtained in the clad member production process 13, and the protection member 16 is obtained in the protection member production process 15. Next, in the preform manufacturing process 17, the clad member 14 is fixed to the side surface of the core member 12 and the protective member 16 is fixed to the side surface of the clad member 14 to obtain the preform 18. Thirdly, the preform 18 is heat-stretched in the longitudinal direction in the heat-stretching step 19 and becomes a stretched body 20 having a cross section substantially similar to the cross section of the preform 18. In the cutting step 21, the stretched body 20 is sliced along a plane perpendicular to the stretching direction to obtain an optical circuit 22 having a desired thickness.

  An optical circuit 22 (FIG. 2D) obtained from the optical circuit manufacturing process 10 is formed in a Y-shape, and light incident / exit portions 23a to 23c for entering and exiting light and light incident / exit portions 23a to 23c. And a core portion 24 including an optical waveguide 23d for transmitting light therebetween. When the optical circuit 22 is used with the part 23a as the light incident part and the parts 23c and 23b as the light emission parts, the optical circuit 22 becomes an optical circuit having a branch point, the parts 23b and 23c as the light incident parts, and the part 23a as the light. When the optical circuit 22 is used as the emission part, the optical circuit 22 becomes an optical circuit having a junction. The clad portion 25 is formed around the core portion 24 excluding the light incident / exit portions 23a to 23c. Further, a protective layer 26 is formed around the cladding portion 25 that is not adjacent to the optical waveguide 23d. The core part 24, the clad part 25, and the protective layer 26 are in close contact with each other to form the optical circuit 22.

  Next, details of each process of the optical circuit manufacturing process 10 will be described. FIG. 2A shows the core member 12, the cladding members 14 a to 14 c and the protection members 16 a and 16 b manufactured in the core member manufacturing process 11, the cladding member manufacturing process 13 and the protection member manufacturing process 15. The core member 12 includes light incident / exit portions 30a to 30c for entering / exiting light and an optical waveguide 30 for transmitting light between the light incident / exit portions 30a to 30c. The core member 12 is formed in a substantially similar shape to the core portion 24 of the optical circuit 22. Similarly, the clad members 14a to 14c and the protective members 16a and 16b formed of a material having a lower refractive index than the core member 12 are formed in a shape substantially similar to the clad portion 25 and the protective layer 26 of the optical circuit 22. ing.

  The core member 12, the clad member 14, and the protective member 16 are made of a material mainly composed of plastic, and are formed into a desired shape by an injection molding process or a monomer polymerization process such as an interfacial gel polymerization method or a melt extrusion method. Is done. The core member 12 is made of a material having a higher refractive index than the clad member 14. Details of the materials of the core member 12, the clad member 14, and the protection member 16 will be described later.

  In the preform manufacturing process 17, the core member 12, the clad member 14, and the protection member 16 are temporarily fixed using an adhesive, an adhesive tape, or the like to form a rod-shaped preform 18 (FIG. 2B). The preform 18 is formed so that a cross-section having a certain shape is exposed even if cut in any cross-section, and the cross-section is substantially similar to the optical circuit as the final form. It is formed.

  In the heating and stretching step 19, the preform 18 is placed in the heating furnace 35 (FIG. 3). When heated in the heating furnace 35, the lower portion of the preform 18 is melted. Although the melting temperature depends on the thermal characteristics of the material forming the member, it is preferably 80 ° C to 500 ° C, more preferably 120 ° C to 350 ° C, and most preferably 180 ° C to 250 ° C. It is. Drawing (stretching) is performed starting from the tip 18a of the melted portion. The stretched body 20 is wound around the core member 38 of the winding device 37 after passing through the wire diameter monitor 36. When drawing, the outer diameter of the stretched body 20 is monitored by the wire diameter monitor 36 to determine the position of the preform 18 in the heating furnace 35, the temperature of the heating furnace 35, the winding speed of the winding device 37, etc. Adjust as appropriate. In such a heating and stretching step 19, the preform 18 is stretched in the longitudinal direction at a desired stretching ratio (ratio of the cross-sectional area of the stretched body 20 when the cross-sectional area of the preform 18 is used as a reference). Then, the stretched body 20 is obtained (FIG. 2C). The draw ratio in this heating and drawing step 19 can be controlled by the take-off speed or the heating temperature based on the wire diameter monitor 36, and by appropriately controlling this, a desired draw ratio from the range of 2 to 100 million times. Can be selected.

  In the cutting step 21, a desired thickness as shown in FIG. 2D is obtained by cutting the stretched body 20 with a surface perpendicular to the stretching direction using a cutting device having a cutter and mirror-finishing the end surface. The optical circuit 22 can be obtained.

  The core member 12 and the clad member 14 may be fixed, and this fixed body may be used as a preform. Moreover, in the cutting process 21, although it described that it cut | disconnects in a surface perpendicular | vertical to the extending | stretching direction of the extending | stretching body 20, you may cut | disconnect not only in this but in the surface which cross | intersects an extending direction at an acute angle.

  Furthermore, instead of the core member 12 and the clad member 14, the core member 40 (FIG. 4A) having the clad layer 40a or the clad member 41 having the core layer 41a (FIG. 4B) is used. A reform may be configured. The core member 40 or the clad member 41 contains a refractive index adjusting agent and is formed of a material mainly composed of plastic, and has a desired refractive index by controlling the concentration distribution of the refractive index adjusting agent. The clad layer 40a or the core layer 41a can be formed.

  Similarly, instead of the cladding member 14 and the protection member 16, the protection member 42 and the cladding member 42b (FIG. 4C) having the cladding layer 42a, or the cladding member 43 and the cladding member 42b having the protection layer 43a (FIG. 4C). 4 (D)) may be used to form the preform. The protective member 42 and the clad member 43 are formed of a material mainly composed of a plastic containing a functional additive in a range not affecting the optical characteristics in addition to the refractive index adjusting agent. By controlling the concentration distribution of the refractive index adjusting agent contained in the protective member 42, the cladding layer 42a having a desired refractive index can be formed. Similarly, by controlling the concentration distribution of the functional additive contained in the clad member 43, the protective layer 43a having a desired function can be formed.

  In the above embodiment, the optical waveguide 23 formed in the optical circuit 22 is described as being Y-shaped. However, the present invention is not limited to this, and the light input to the light incident part can be output from the light output oblique part. The same effect can be obtained even when an optical waveguide having a shape composed of a straight line, a curved line, or a combination of a straight line and a curved line is used. For example, the optical circuit 47 shown in FIG. 5A has light incident / exit portions 47a and 47b, and an optical waveguide 47c connecting these portions 47a and 47b is formed in a straight line. The optical circuit 49 shown in FIG. 5B has light incident / exit portions 49a and 49b, and an optical waveguide 49c connecting these portions 49a and 49b is formed in a curved shape. Such optical waveguides 47c and 49c are preferably formed according to the arrangement position and shape of the light incident / exit site of the external device 50 in the optical circuits 47 and 49. A preform having a cross section substantially similar to the optical circuits 47 and 49 having such optical waveguides 47c and 49c is formed, and the preform is stretched at a desired stretch ratio and cut into a desired thickness. Therefore, an optical circuit corresponding to any external device 50 can be easily and inexpensively manufactured.

  Next, the optical circuit manufacturing process 60 which is the 2nd Embodiment of this invention is demonstrated using FIG. Note that here, differences from the first embodiment will be described in detail, and detailed descriptions of parts similar to those in the first embodiment will be omitted. First, a rod-shaped core member 62 is obtained in the core member manufacturing process 61, a rod-shaped cladding member 64 is obtained in the cladding member manufacturing process 63, and a rod-shaped protection member 66 is obtained in the protection member manufacturing process 65. Next, in the preform manufacturing process 67, these members 62, 64 and 66 are fixed to obtain a preform 68. The preform 68 is formed so that a cross-section of a certain shape is exposed even if it is cut in any cross-section, and the cross-section is substantially similar to the final optical circuit. It is formed. Thirdly, the preform 68 becomes a stretched body 70 having a cross section substantially similar to the cross section of the preform 68 through the heating and stretching step 69. The stretched body 70 is cut into a desired thickness in the cutting step 71 to form an optical circuit 72. In the laminating step 73, clad thin pieces 74 and 75 (FIG. 7) are sequentially laminated on both surfaces of the optical circuit 72 to obtain a laminated optical circuit 76.

  The clad flakes 74 and 75 are made of the same material as that of the clad member 64, and are subjected to the processes of steps 69 and 71 on a preform having a shape substantially the same as the outer shape of the cross section of the preform 68. Obtainable.

  The exposed surfaces 72b and 72c of the optical waveguide 72a formed on the optical circuit 72 and exposed to the outside are used, and the clad thin pieces 74, the optical circuit 72, and the exposed surfaces 72b and 72c are covered by using the clad thin pieces 74 and 75. The clad flakes 75 are sequentially laminated to obtain a laminated optical circuit 76 (FIG. 8). Thus, by covering the exposed surfaces 72b and 72c with the clad flakes 74 and 75 having a refractive index lower than that of the optical circuit 72, the numerical aperture in the thickness direction of the optical circuit 72 is improved, and the laminate has excellent transmission characteristics. The optical circuit 76 can be manufactured.

  The optical circuit 72 and the clad thin pieces 74 and 75 can be fixed to each other easily within a range that does not affect the optical characteristics, such as a heating and pressurizing method, an ultrasonic welding method, a vibration welding method, or the like. Any material may be used.

  9 and 10, the optical circuits 80 to 82 having the optical waveguides 80 a to 82 a having different shapes are used, and the optical circuits 80 to 82 are sequentially arranged so that a part of the optical waveguides 80 a to 82 a overlap each other. By laminating, it is also possible to manufacture a laminated optical circuit 84 having an optical waveguide in the thickness direction. For the fixing of the optical circuits 80 to 82, an adhesive having a refractive index equivalent to that of the optical circuits 80 to 82 is used, or in a range that does not affect the optical characteristics, a heating and pressing method, an ultrasonic welding method, or the like. Alternatively, a vibration welding method or the like may be applied.

  In addition, an optical circuit having a voltage-driven switching function can be manufactured by using, as the core member, a material whose optical characteristics change with voltage application. For example, as shown in FIG. 11, the clad members 86a and 86b having electrode members 85a and 85b formed of conductive plastic and the core member 86c formed of a material whose refractive index changes according to the applied voltage are fixed. A preform 86 is formed. The preform 86 is formed such that a cross-section having a certain shape is exposed even if cut in any cross-section, and the cross-section is substantially similar to the optical circuit as the final form. It is formed. The electrode members 85a and 85b are arranged to face each other with the core member 86c interposed therebetween. The preform 86 is subjected to processes 69, 71 and 73 to obtain an optical circuit 87 (FIG. 12). By applying a predetermined voltage between the electrode portions 87a and 87b of the optical circuit 87, the refractive index of the optical waveguide 88 sandwiched between the electrode portions 87a and 87b changes. In this way, an optical circuit 87 having a voltage drive type switching function can be manufactured.

  Note that an optical circuit having this switching function can also be manufactured using a method of laminating a plurality of thin pieces. The laminated optical circuit 90 shown in FIGS. 13 and 14 is formed so that the clad thin piece 91, the optical circuit 92, and the clad thin piece 93 are laminated in order. The optical circuit 92 is obtained by stretching and cutting a preform made of a core member made of a material whose refractive index changes according to the applied voltage, and a clad member having a lower refractive index than the core member. The clad flakes 91 and 93 can be obtained by stretching a preform composed only of a clad member and an electrode member and cutting it to a desired thickness. Further, the electrode portions 91 a and 93 a on the clad thin pieces 91 and 93 are formed at positions facing each other through the optical waveguide 94 of the optical circuit 92 when the laminated optical circuit 90 is formed. By applying a predetermined voltage between the electrode portions 91a and 93a of such a laminated optical circuit 90, the refractive index of the optical waveguide 94 can be changed.

  Examples of the material of the core member whose refractive index changes depending on the applied voltage include the electric field alignment polymer described in Toyota Chuken R & D Review Vol. 34 No. 1 (1993.3), pages 31 to 39.

  The core member may be made of a material whose light absorption rate or light scattering rate varies depending on the applied voltage. Examples of the material for the core member include the following. As a material whose light absorption rate changes, there is a general electrochromic material.

  In the above embodiment, as means for changing the optical characteristics (refractive index, light absorption rate, and light scattering rate) of the core portion, an electrode portion is provided so as to face the core portion, and this electrode portion is provided. Although it has been described that a material whose predetermined optical characteristics change depending on the applied voltage is used for the core member, the present invention is not limited to this, and the core member is made of a material whose optical characteristics change depending on parameters indicating changes in the external environment other than the voltage. It may be formed. Preferred parameters include acceleration (including gravity) applied to the core member, pressure change such as water pressure and pressure of the core member, temperature change of the core member, and electromagnetic waves to the core member (visible light, infrared light, ultraviolet light and radio waves). Etc.), changes in the concentration of specific gases (water vapor, oxygen, carbon dioxide, etc.) and liquids (alcohol, etc.), etc., and a material whose optical properties change according to these changes is used as the core member By using it, an equivalent effect can be obtained. Furthermore, using a voltage application device connected to various sensors, a switch corresponding to changes in the external environment of the optical circuit is created by applying a predetermined voltage to the core member according to the detection signal output by this sensor. It is also possible to do. This sensor includes, for example, an acceleration (including gravity) sensor, a pressure sensor (water pressure, atmospheric pressure, etc.), a temperature sensor, a concentration sensor of a specific gas (water vapor, oxygen, carbon dioxide, etc.) or liquid (alcohol, etc.), etc. Can be given.

  Next, materials used for the core portion, the clad portion, the protective layer, and the electrode portion constituting the preform will be described. Basically, it is not particularly defined as long as it is used in an optical circuit, but preferable ones are described below.

(Core part)
As the polymerizable monomer for the raw material of the core part, it is preferable to select a raw material that can be easily bulk-polymerized. Moreover, it is preferable if the obtained polymer is thermoplastic, has good processability, and has high light transmittance. Examples of raw materials that are highly light transmissive and easy to bulk polymerize include the following (meth) acrylic acid esters (fluorine-free (meth) acrylic acid ester (a), fluorine-containing (meth) acrylic acid ester (b) , Styrene compounds (c), vinyl esters (d), etc., and the core part is a homopolymer of these, or a copolymer comprising two or more of these monomers, and a homopolymer and / or a copolymer. Of these, a composition containing (meth) acrylic acid ester as a polymerizable monomer can be preferably used.

  Specific examples of the polymerizable monomer listed above include (a) fluorine-free methacrylic acid ester and fluorine-free acrylic acid ester: methyl methacrylate (MMA), ethyl methacrylate, isopropyl methacrylate, methacrylic acid-tert -Butyl, benzyl methacrylate (BzMA), phenyl methacrylate, cyclohexyl methacrylate, diphenylmethyl methacrylate, tricyclo [5.2.1.0.6] decanyl methacrylate, adamantyl methacrylate, isobornyl methacrylate, norbornyl Examples thereof include methacrylate, and examples thereof include methyl acrylate, ethyl acrylate, tert-butyl acrylate, and phenyl acrylate. In addition, (b) fluorine-containing acrylic acid ester and fluorine-containing methacrylate ester include 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,3,3 , 3-Pentafluoropropyl methacrylate, 1-trifluoromethyl-2,2,2-trifluoroethyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2, 3,3,4,4-hexafluorobutyl methacrylate and the like. Furthermore, (c) styrene compounds include styrene, α-methylstyrene, chlorostyrene, bromostyrene, and the like. Furthermore, (d) vinyl esters include vinyl acetate, vinyl benzoate, vinyl phenyl acetate, vinyl chloroacetate and the like. Of course, it is not limited to these. The type and composition ratio of the constituent monomers are selected so that the refractive index of the polymer of the core portion made of a monomer alone or a copolymer is equal to or higher than that of the outermost peripheral portion. A particularly preferred polymer is an acrylic resin (PMMA) which is a transparent resin. In addition, the material of the core part can be selected in accordance with uses such as heat resistance and low hygroscopicity.

(Clad part)
In order that the light transmitted through the core part is totally reflected at the interface of the core part, it is preferable to provide a cladding part on the outer periphery of the core part. When providing a clad part, it is preferable to use the one having a refractive index lower than that of the core part and having good adhesion to the core part. However, in the case where irregularity of the interface between the core part and the clad part is likely to occur due to selection of the material or it is not preferable in terms of manufacturing suitability, a layer may be further provided between the core part and the clad part. For example, by forming an outer core layer made of a polymer having the same composition as the matrix of the core part at the interface with the core part (that is, the inner wall surface of the hollow tube), the interface state between the core part and the cladding part is corrected. can do. Details of the outer core layer will be described later. Of course, without forming the outer core layer, the cladding itself can be formed from a polymer having the same composition as the matrix of the core.

  As the material for the clad part, a material excellent in toughness and heat and heat resistance is preferably used. For example, it preferably comprises a homopolymer or copolymer of a fluorine-containing monomer. As the fluorine-containing monomer, vinylidene fluoride (PVDF) is preferable, and a fluorine resin obtained by polymerizing one or more polymerizable monomers containing 10% by mass or more of vinylidene fluoride is preferably used.

  Moreover, when forming a clad part by shape | molding a polymer with the below-mentioned melt extrusion method, it is necessary for the melt viscosity of a polymer to be suitable. As for the melt viscosity, the molecular weight is used as a correlated physical property, and particularly has a correlation with the weight average molecular weight. In the present invention, the weight average molecular weight is suitably in the range of 10,000 to 1,000,000, more preferably in the range of 50,000 to 500,000.

(Polymerization initiator)
When the core part and / or the clad part are made from a polymer polymerized from a polymerizable monomer, a polymerization initiator is used in the polymerization. As a polymerization initiator, it can select suitably according to the monomer and polymerization method to be used, for example, benzoyl peroxide (BPO), tert- butyl peroxy-2-ethyl hexanate (PBO), di-tert-butyl. Examples thereof include peroxide compounds such as peroxide (PBD), tert-butyl peroxyisopropyl carbonate (PBI), and n-butyl-4,4-bis (tert-butylperoxy) valerate (PHV). 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylpropane), 2,2′-azobis (2-methylbutane), 2,2′-azobis (2-methylpentane), 2,2′-azobis (2,3-dimethylbutane), 2,2 '-Azobis (2-methylhexane), 2,2'-azobis (2,4-dimethylpentane), 2,2'-azobis (2,3,3-trimethylbutane), 2,2'-azobis (2 , 4,4-trimethylpentane), 3,3′-azobis (3-methylpentane), 3,3′-azobis (3-methylhexane), 3,3′-azobis (3,4-dimethylpentane), 3,3′-azobis (3-ethylpentane , Dimethyl-2,2′-azobis (2-methylpropionate), diethyl-2,2′-azobis (2-methylpropionate), di-tert-butyl-2,2′-azobis (2- And azo compounds such as methyl propionate). Of course, the polymerization initiator is not limited to these, and two or more kinds may be used in combination.

(Chain transfer agent)
The polymerizable composition for molding a core part and the polymerizable composition for molding a clad part preferably contain a chain transfer agent. The chain transfer agent is mainly used for adjusting the molecular weight of the polymer. When the polymerizable composition for molding the clad part and the core part each contains a chain transfer agent, the polymerization rate and the degree of polymerization can be more controlled by the chain transfer agent when molding the polymer from the polymerizable monomer. The molecular weight of the polymer can be adjusted to a desired molecular weight. For example, when the obtained preform is drawn by drawing, the mechanical properties at the time of drawing can be adjusted to a desired range by adjusting the molecular weight, which contributes to improvement of productivity.

  About the said chain transfer agent, according to the kind of polymerizable monomer used together, a kind and addition amount can be selected suitably. The chain transfer constant of the chain transfer agent for each monomer can be referred to, for example, Polymer Handbook 3rd Edition (J. BRANDRUP and EH IMMERGUT edition, published by JOHN WILEY & SON). The chain transfer constant can also be obtained by experiment with reference to Takayuki Otsu and Masato Kinoshita, “Experimental Methods for Polymer Synthesis”, Kagaku Dojin, published in 1972.

  Examples of the chain transfer agent include alkyl mercaptans (eg, n-butyl mercaptan, n-pentyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, tert-dodecyl mercaptan), thiophenols (eg, thiophenol, m- Bromothiophenol, p-bromothiophenol, m-toluenethiol, p-toluenethiol, etc.) are preferably used. In particular, it is preferable to use an alkyl mercaptan such as n-octyl mercaptan, n-lauryl mercaptan, and tert-dodecyl mercaptan. A chain transfer agent in which a hydrogen atom of a C—H bond is substituted with a deuterium atom (D) or a fluorine atom (F) can also be used. Of course, the chain transfer agent is not limited to these, and two or more of these chain transfer agents may be used in combination.

(Refractive index modifier)
It is preferable to add a refractive index adjusting agent to the polymerizable composition for the core part. In some cases, the clad part polymerizable composition may contain a refractive index adjusting agent. By providing a distribution of the concentration of the refractive index adjusting agent, a refractive index distribution type core can be easily produced based on the concentration distribution. Even without using a refractive index adjusting agent, it is possible to introduce a refractive index distribution structure by using two or more kinds of polymerizable monomers for forming the core part and having a distribution of the copolymerization ratio in the core part. It is preferable to use a refractive index adjusting agent in view of the ease of production and the like as compared with the composition ratio control of copolymerization.

The refractive index adjusting agent is also called a dopant, and is a compound different from the refractive index of the polymerizable monomer used together. The refractive index difference is preferably 0.005 or more. The dopant has the property that the polymer containing it has a higher or lower refractive index than the additive-free polymer. These have a difference in solubility parameter of 7 (cal / cm ^{3) in} comparison with a polymer produced by monomer synthesis as described in Japanese Patent No. 3332922 and JP-A-5-173026. ) Within ^1/2 , the difference in refractive index is 0.001 or more, and the polymer containing this has the property that the refractive index changes compared to the additive-free polymer. Any of those which can stably coexist and are stable under the polymerization conditions (polymerization conditions such as heating and pressurization) of the polymerizable monomer which is the above-mentioned raw material can be used.

  Using the above-mentioned properties as a dopant that can stably coexist with the polymer and is stable under the polymerization conditions (polymerization conditions such as heating and pressurization) of the above-described raw material polymerizable monomer. Can do. In this embodiment, the core part-forming polymerizable composition contains a dopant, and in the step of forming the core part, the progress direction of polymerization is controlled by an interfacial gel polymerization method, and the concentration of the dopant is given a gradient. A method for forming a refractive index distribution structure based on the dopant concentration distribution is shown as an example.

  The dopant may be a polymerizable compound. When a dopant of the polymerizable compound is used, the copolymer containing this as a copolymerization component has a property of increasing the refractive index as compared with a polymer not containing the copolymer. Use what has. Examples of such a copolymer include MMA-BzMA copolymer.

  Examples of the dopant include benzyl benzoate (BEN), diphenyl sulfide (DPS), triphenyl phosphate (TPP), and phthalic acid as described in Japanese Patent No. 3332922 and JP-A-11-142657. Examples include benzyl-n-butyl (BBP), diphenyl phthalate (DPP), diphenyl (DP), diphenylmethane (DPM), tricresyl phosphate (TCP), diphenyl sulfoxide (DPSO), diphenyl sulfide derivatives, and dithian derivatives. Among them, BEN, DPS, TPP, DPSO, sulfurized diphenyl derivatives, and dithian derivatives are preferable. In addition, compounds obtained by substituting hydrogen atoms present in these compounds with deuterium atoms can also be used for the purpose of improving transparency in a wide wavelength region. Examples of the polymerizable compound include tribromophenyl methacrylate. When a polymerizable compound is used as the refractive index adjusting component, it is difficult to control various properties (particularly optical properties) because the polymerizable monomer and the polymerizable refractive index component are copolymerized when the matrix is formed. However, it may be advantageous in terms of heat resistance. Furthermore, it is also preferable to use inorganic nanoparticles that can increase the refractive index while suppressing an increase in scattering due to the addition as a dopant.

  By adjusting the concentration and distribution of the refractive index adjusting agent, the refractive index of the core part or core layer and the clad part or clad layer constituting the preform can be changed to a desired value. The amount added is appropriately selected according to the use and the member to be combined. A plurality of types of refractive index adjusting agents may be added. In addition, it is preferable that the refractive index difference between the core part and the clad part is 0.0001 or more and 0.02 or less.

  Additives such as MMA, which is a polymerizable monomer, low molecular compounds having a high refractive index, which are refractive index adjusting agents, and polymerization initiators, are added to the clad portion. Then, by starting the polymerization, a GI-type core whose refractive index increases in a substantially square distribution from the outer periphery toward the center can be formed.

(Other additives)
In addition, other additives can be added to the polymerizable composition for producing them in the core part, the clad part, or a part thereof, as long as the optical transmission performance is not deteriorated. For example, a stabilizer can be added to the core portion or a part thereof for the purpose of improving weather resistance, durability and the like. Further, for the purpose of improving optical transmission performance, a stimulated emission functional compound for optical signal amplification can be added. By adding the stimulated emission functional compound, the attenuated signal light can be amplified by the excitation light, and the transmission distance is improved. For example, it can be used as an optical fiber amplifier in a part of the optical transmission link. . These additives can also be contained in the core part, the clad part, or a part of them by adding to the raw material monomer and then polymerizing.

(Protective layer forming material)
An optical circuit with a protective layer having a protective layer around an optical circuit composed of a core part and a clad part has increased mechanical strength and is easy to handle. As the protective layer forming material used for the optical circuit with the protective layer, a material that does not cause thermal damage (for example, deformation, modification, thermal decomposition, etc.) to the optical circuit to be coated is selected. Therefore, it is preferable to use a polymer that can be cured at a glass transition temperature Tg (° C.) or lower and (Tg−50) ° C. or higher of the polymer forming the optical circuit. Further, in order to reduce production cost, it is more preferable to use a molding time (time for curing the material) of 1 second to 10 minutes, preferably 1 second to 5 minutes. When the optical circuit is formed from a plurality of polymers, the glass transition temperature at the lowest temperature among the glass transition temperatures of each polymer is regarded as Tg (° C.). In the case where the glass transition temperature Tg (° C.) is not higher than room temperature (for example, about −40 ° C. for PVDF) such as PVDF, or in the case of a polymer having no glass transition temperature, other phase transition temperatures, for example, The melting point is taken as the reference temperature.

  In addition to general olefin polymers such as polyethylene (PE) and polypropylene (PP), and highly versatile polymers such as vinyl chloride and nylon, specific materials for protective layer formation include: Can be mentioned. Since these have high elasticity, they are also effective from the viewpoint of imparting mechanical properties such as bending. First, rubber which is one form of the polymer can be mentioned. Specifically, isoprene-based rubber (for example, natural rubber, isoprene rubber, etc.), butadiene-based rubber (for example, styrene-butadiene copolymer rubber, butadiene rubber), diene special rubber (for example, nitrile rubber, chloroprene rubber, etc.) ), Olefin rubber (for example, ethylene-propylene rubber, acrylic rubber, butyl rubber, halogenated butyl rubber, etc.), ether rubber, polysulfide rubber, urethane rubber and the like.

  Moreover, the liquid rubber which lose | disappears the fluidity | liquidity and hardens | cures by showing fluidity | liquidity at room temperature and heating can be used as a protective layer formation material. Specifically, polydiene-based (for example, basic structure is polyisoprene, polybutadiene, butadiene-acrylonitrile copolymer, polychloroprene, etc.), polyolefin-based (for example, basic structure is polyolefin, polyisobutylene, etc.), polyether-based (for example, , Basic structure is poly (oxypropylene), etc., polysulfide type (eg, basic structure is poly (oxyalkylene disulfide), etc.), polysiloxane type (eg, basic structure is poly (dimethylsiloxane), etc.) Can do.

  As a material for the protective layer, thermoplastic elastomer (TPE) can also be used. Thermoplastic elastomers are a group of substances that exhibit rubber elasticity at room temperature, are plasticized at high temperatures, and are easy to mold. Specific examples include styrene TPE, olefin TPE, vinyl chloride TPE, urethane TPE, ester TPE, amide TPE, and the like. The polymers listed above are not limited to the above materials as long as they can be molded at or below the glass transition temperature Tg (° C.) of the polymer of the optical circuit, particularly the polymer of the core portion. Copolymers or mixed polymers can also be used.

(Functional additives)
In some cases, a functional additive is added to the material for forming the core portion, the clad portion, and the protective layer. Examples of the additive include a conductive material for preventing static charge, a flame retardant material, and a coloring dye or pigment. Although the specific example of an additive is given to the following, it is not limited to this. Examples of conductive materials include fine particles of noble metals such as tin, zinc alloy powder and silver, examples of flame retardant materials include metal hydroxides such as magnesium hydroxide and aluminum hydroxide, and examples of coloring pigments include carbon black, Titanium oxide, zirconium oxide and the like are preferably used. Carbon black is low-cost, and when used as a coating material for optical fibers, it has antistatic properties in addition to coloring, making it difficult to be charged with static electricity. It is particularly preferable because it has many advantages such as being restrained from being returned to the outside of the optical fiber due to bending or the like. In addition, when it is estimated that the light leakage intensity is not large, it can be used without greatly degrading the S / N ratio by reducing the power of the noise light by using the core member containing the light scatterer. Is possible.

(Electrode part)
It is preferable to use a conductive polymer as the electrode portion forming material. Specifically, a polymer containing metal powder such as silver, iron or stainless steel in a thermoplastic resin, or carbon black or CNT (carbon nanotube). ) And the like.

  A rod-shaped preform having a rectangular cross section with a length of 80 mm, a length of 50 mm, and a width of 30 mm is fixed to a core member cut out from a bulk copolymer of MMA and IBXMA and a clad portion obtained by injection molding of PMMA. Created. This preform is heated at about 230 ° C. in a heating furnace, and the preform is stretched in the longitudinal direction at a stretch ratio of about 10,000 times, and has a rectangular cross section of 200 mm in length, 0.5 mm in length and 0.3 mm in width. A stretched body was obtained. The stretched body was cut along a plane perpendicular to the longitudinal direction to produce an optical circuit having a thickness of 0.2 mm having a Y-branch optical waveguide composed of one light incident part and two light output parts. Using two clad flakes with a thickness of 0.15 mm, the optical circuit was laminated so as to sandwich both surfaces thereof, and a laminated optical circuit having a Y-branch optical waveguide was produced. It was confirmed that the light incident from the light incident portion of the laminated optical circuit was emitted from the two light emitting portions of the laminated optical circuit.

  The core member and the protective member were prepared by PMMA injection molding. A predetermined surface of the protective member was subjected to a fluorine-based resin coating treatment to prepare a protective member having a cladding layer. The core member and the protective member were fixed so that the clad layer was in contact with the core member, and a rod-shaped preform having a rectangular cross section of length 80 mm, length 50 mm, width 30 mm was prepared. This preform is heated at about 230 ° C. in a heating furnace, and the preform is stretched in the longitudinal direction at a stretch ratio of about 10,000 times, and has a rectangular cross section of 200 mm in length, 0.5 mm in length and 0.3 mm in width. A stretched body was obtained. The stretched body was cut along a plane perpendicular to the longitudinal direction to produce an optical circuit having a thickness of 0.2 mm having a Y-branch optical waveguide composed of one light incident part and two light output parts. Using two protective thin pieces (thickness 0.15 mm) having a clad layer on one side, this optical circuit was laminated so as to be sandwiched between clad layers, and a laminated optical circuit having a Y-branch optical waveguide was produced. It was confirmed that the light incident from the light incident portion of the laminated optical circuit was emitted from the two light emitting portions of the laminated optical circuit.

It is explanatory drawing which shows the optical circuit manufacturing process of the 1st Embodiment of this invention. It is explanatory drawing which shows the molded object in each process shown in FIG. It is explanatory drawing which shows the outline | summary of the heating extending | stretching apparatus used at a heating extending process. (A) is a perspective view which shows the outline | summary of the core member which has a clad layer. (B) is a perspective view showing an outline of a clad member having a core layer, (C) is a protective member having a clad layer, and (D) is a clad member having a protective layer. (A) is a perspective view which shows the outline | summary of the optical circuit which has an optical waveguide formed only from a straight line. (B) is a perspective view showing an outline of an optical circuit having an optical waveguide formed only from a curve. It is explanatory drawing which shows the optical circuit manufacturing process of the 2nd Embodiment of this invention. It is a perspective view which shows the outline | summary of a lamination process. FIG. 8 is a sectional view taken along line VIII-VIII ′ of the laminated optical circuit having the optical waveguide in the plane direction shown in FIG. 7. It is a perspective view which shows the outline | summary of the lamination process which concerns on the laminated optical circuit which has an optical waveguide of the thickness direction. FIG. 10 is a cross-sectional view taken along line X-X ′ of the laminated optical circuit having the optical waveguide in the thickness direction shown in FIG. 9. It is a perspective view which shows the outline | summary of the preform formed from the clad member which has an electrode member, and a core member. It is a perspective view which shows the outline | summary of the optical circuit with an electrode part obtained by giving each process of a heating extending process and a cutting process to the preform of FIG. It is a perspective view which shows the outline | summary of the lamination process which concerns on the laminated optical circuit with an electrode part. FIG. 14 is a cross-sectional view taken along the line XIV-XIV ′ of the laminated optical circuit with an electrode portion illustrated in FIG. 13.

Explanation of symbols

10, 60 Optical circuit manufacturing process 11, 61 Core member manufacturing process 12, 40, 62, 86c Core member 13, 63 Clad member manufacturing process 14, 41, 42b, 43, 64, 86a, 86b Clad member 15, 65 Protection member Manufacturing process 16, 42, 66 Protective member 17, 67 Preform manufacturing process 18, 68, 86 Preform 19, 69 Heat drawing process 20, 70 Stretched body 21, 71 Cutting process 22, 47, 49, 72, 72a, 80 ˜82, 87, 92 Optical circuits 23a-23c, 30a-30c 47a, 47b, 49a, 49b Light incident / exit portions 23d, 30, 47c, 49c, 80a-82a, 88, 94 Optical waveguide 24 Core portion 25 Clad portion 26 Protective layer 36 Wire diameter monitor 40a Clad layer 41a Core layer 42a Clad layer 43a Protective layer 73 Lamination process 74 75, 91, 93 Clad thin piece 76, 84, 90 Laminated optical circuit 72b, 72c Exposed surface 85a, 85b Electrode members 87a, 87b, 91a, 93a Electrode portion

Claims (8)

A plastic core member having a light incident part for inputting external light to a side surface, a light emitting part for outputting internal light from the light incident part, and an optical waveguide connecting the light incident part and the light emitting part; A first step of forming a rod-shaped preform having the same cross-sectional shape by combining with a plastic clad member disposed on the side surface of the core member;
A second step of heating and stretching the preform in the longitudinal direction to form a stretched body having a cross section substantially similar to the cross section of the preform;
A method of manufacturing an optical circuit, comprising: a third step of slicing the stretched body in a direction intersecting the stretching direction to obtain a flake composed of the core member and the clad member.   2. The method of manufacturing an optical circuit according to claim 1, further comprising a fourth step of laminating the sub-strip on both sides of the slice.   3. The method of manufacturing an optical circuit according to claim 2, wherein the sub-slice is made of the same material as that of the clad member.   4. The method according to claim 1, further comprising a fifth step of forming a plurality of the thin pieces in which the shape of the core member is changed, and laminating so as to connect a part of the core members of the thin pieces. The manufacturing method of the optical circuit of description. The clad member includes an electrode part having conductivity,
5. The method of manufacturing an optical circuit according to claim 1, wherein the core member is formed of a material whose optical characteristics change according to an applied voltage between the electrode portions.   6. The method of manufacturing an optical circuit according to claim 5, wherein the optical characteristic is any one of a refractive index, a light absorption rate, and a light scattering rate.   7. The method of manufacturing an optical circuit according to claim 1, wherein a protective layer is disposed on a side surface of the clad member.   8. The method of manufacturing an optical circuit according to claim 2, wherein the thin piece includes at least one of the light incident part and the light emitting part.

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