JP2012163838A - Manufacturing method of optical waveguide, optical waveguide, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical waveguide which can efficiently manufacture an optical waveguide having a refractive index distribution of a grated index type or similar to that at a low cost; an optical waveguide having a small transmission loss and high reliability; and an electronic apparatus equipped with the optical waveguide.SOLUTION: A manufacturing method of an optical waveguide comprises a first step for forming a layer 910 containing a polymer 915; and a second step for forming a refractive index distribution in the layer 910 by irradiating the layer 910 with an active radiation beam 930, isomerizing or dimerizing a part of a chemical structure in the polymer 915 to change a refractive index. In the second step, an active radiation is projected through a mask 935 having a predetermined transmittance distribution, so as to continuously change the integrated light amount of the active radiation 930. Therefore, the refraction index distribution of a grated index type is formed.

Description

  The present invention relates to an optical waveguide manufacturing method, an optical waveguide, and an electronic device.

  In recent years, with the wave of computerization, wideband lines (broadband) capable of communicating a large amount of information at high speed have been spreading. Also, as devices for transmitting information to these broadband lines, transmission devices such as router devices and WDM (Wavelength Division Multiplexing) devices are used. In these transmission apparatuses, a large number of signal processing boards in which arithmetic elements such as LSIs and storage elements such as memories are combined are installed, and each line is interconnected.

  Each signal processing board has a circuit in which arithmetic elements, storage elements, etc. are connected by electrical wiring. However, with the increase in the amount of information to be processed in recent years, each board has a very high throughput. It is required to transmit. However, with the speeding up of information transmission, problems such as generation of crosstalk and high frequency noise and deterioration of electric signals are becoming apparent. For this reason, electrical wiring becomes a bottleneck, making it difficult to improve the throughput of the signal processing board. Similar problems are also becoming apparent in supercomputers and large-scale servers.

  On the other hand, an optical communication technique for transferring data using an optical carrier wave has been developed, and in recent years, an optical waveguide is becoming popular as a means for guiding the optical carrier wave from one point to another point. This optical waveguide has a linear core part and a clad part provided so as to cover the periphery thereof. The core part is made of a material that is substantially transparent to the light of the optical carrier wave, and the cladding part is made of a material having a refractive index lower than that of the core part.

  In the optical waveguide, light introduced from one end of the core portion is conveyed to the other end while being reflected at the boundary with the cladding portion. A light emitting element such as a semiconductor laser is disposed on the incident side of the optical waveguide, and a light receiving element such as a photodiode is disposed on the emission side. Light incident from the light emitting element propagates through the optical waveguide, is received by the light receiving element, and performs communication based on the flickering pattern of the received light or its intensity pattern.

  By replacing the electric wiring in the signal processing board with such an optical waveguide, it is expected that the problem of the electric wiring as described above is solved and the signal processing board can be further increased in throughput.

  Here, as the optical waveguide, conventionally, a step index type having a core portion having a constant refractive index and a clad portion having a constant refractive index lower than the core portion has been generally used. A graded index type with a continuously changing refractive index has been proposed.

  For example, Patent Document 1 proposes an optical waveguide in which the refractive index is distributed concentrically in a cross section by supplying a refractive index adjusting agent into a polymer substrate. According to such a graded index type optical waveguide, it is said that transmission loss can be reduced as compared with a step index type.

  As a method for supplying a refractive index adjusting agent to a polymer substrate, Patent Document 1 includes methods such as coating, spraying, adhesion, dipping, and deposition.

  However, in the method of supplying the refractive index adjusting agent in this way, the supply amount is not uniform, and accordingly, an unintended bias occurs in the refractive index distribution in the polymer substrate. Further, since the work is complicated, it is difficult to increase the manufacturing efficiency of the optical waveguide.

  Recently, there has been a strong demand for an optical waveguide with a large capacity, and further multi-channel and higher density are required. As the number of channels increases and the density increases, the pitch of the channel (core portion) becomes narrower. Accordingly, the accuracy of the position where the refractive index adjusting agent is supplied must be increased. However, there is a limit to the improvement in positional accuracy, and it is not possible to cope with the manufacture of a narrow pitch optical waveguide.

JP 2006-276735 A

  An object of the present invention is to provide a method of manufacturing an optical waveguide capable of efficiently and inexpensively manufacturing an optical waveguide having a graded index type or a refractive index distribution similar thereto, an optical waveguide having a small transmission loss and high reliability, and such an optical waveguide. An object of the present invention is to provide an electronic device including a waveguide.

Such an object is achieved by the present inventions (1) to (9) below.
(1) At least two clad parts and a core provided adjacently between the two clad parts and having a refractive index distribution in which the refractive index continuously decreases from the central part toward the clad parts. A method of manufacturing an optical waveguide having a portion,
A first step of forming a layer containing a polymer whose refractive index changes due to isomerization or dimerization of a part of the chemical structure by irradiation with actinic radiation;
Irradiating the layer with actinic radiation through a mask to form the refractive index profile in the layer, and
The method of manufacturing an optical waveguide, wherein the mask includes a transmission portion having a region in which the transmittance of the active radiation is continuously changed.

  (2) The method for manufacturing an optical waveguide according to (1), wherein the mask is set such that the transmittance of the active radiation continuously decreases or increases as the distance from the vicinity of the center line of the transmission portion increases.

  (3) The method for manufacturing an optical waveguide according to (2), wherein the transmittance distribution in the transmissive portion is axisymmetric with respect to the center line.

  (4) The method for producing an optical waveguide according to any one of (1) to (3), wherein the chemical structure is at least one of an azobenzene group, a maleimide group, a coumarin group, a cinnamoyl group, and an indene group.

  (5) The optical waveguide according to any one of (1) to (4), wherein the polymer has a main chain and a side chain branched from the main chain and including the chemical structure. Production method.

  (6) The method for manufacturing an optical waveguide according to any one of (1) to (5), wherein the polymer is a norbornene-based polymer.

  (7) The said active radiation is a manufacturing method of the optical waveguide in any one of said (1) thru | or (6) which has a peak wavelength in the range of 200-450 nm.

  (8) An optical waveguide manufactured by the method for manufacturing an optical waveguide according to any one of (1) to (7).

  (9) An electronic apparatus comprising the optical waveguide according to (8).

  According to the present invention, a graded index type or similar refractive index distribution is formed on a predetermined region simply by irradiating actinic radiation through a mask, whereby an optical waveguide having excellent transmission efficiency. In addition, the optical waveguide can be efficiently manufactured at a low cost.

  In addition, according to the present invention, a highly reliable electronic device can be obtained by using the optical waveguide.

1 is a perspective view showing an embodiment of an optical waveguide of the present invention (partially cut out and shown through). 1 is a diagram illustrating an example of a refractive index distribution when the horizontal axis indicates the position of the core layer thickness at the center line C1 and the vertical axis indicates the refractive index. It is a figure for demonstrating the 1st manufacturing method of the optical waveguide shown in FIG. It is a figure for demonstrating the 1st manufacturing method of the optical waveguide shown in FIG. It is a figure which shows the structure of a mask. It is a top view which shows a mode that a mask is scanned in the 1st manufacturing method, irradiating actinic radiation with respect to a layer. The relationship between the position on the YY line cross section shown in FIG. 6 and the transmittance of active radiation that passes through the mask, the relationship between the position on the YY line cross section and the integrated light amount, and the position and activity on the YY line cross section. It is a figure which shows the relationship with the refractive index of the layer 910 after irradiation of a radiation. It is a figure for demonstrating the 1st manufacturing method of the optical waveguide shown in FIG. It is a figure for demonstrating the 1st manufacturing method of the optical waveguide shown in FIG. It is a figure for demonstrating the 1st manufacturing method of the optical waveguide shown in FIG. It is an example of the top view and sectional drawing of a mask which are shown in FIG. 12 is another configuration example of the mask shown in FIG. 12 is another configuration example of the mask shown in FIG. It is a figure which shows the structure of a mask in the 2nd manufacturing method.

  Hereinafter, the manufacturing method of an optical waveguide of the present invention, an optical waveguide, and electronic equipment are explained in detail based on a suitable embodiment shown in an accompanying drawing.

<Optical waveguide>
First, the optical waveguide of the present invention will be described.

  FIG. 1 is a perspective view showing an embodiment of an optical waveguide according to the present invention (partially cut out and shown in a transparent manner), and FIG. 2 is a cross-sectional view taken along line XX shown in FIG. It is a figure which shows an example of refractive index distribution when taking the position in the centerline C1 of the thickness of a layer, and taking a refractive index on a vertical axis | shaft. In the following description, the upper side in FIG. 1 is referred to as “upper” and the lower side is referred to as “lower”. 1 is exaggerated in the thickness direction of the layer (vertical direction in FIG. 1).

  The optical waveguide 1 shown in FIG. 1 functions as an optical wiring that transmits an optical signal from one end to the other end.

Hereinafter, each part of the optical waveguide 1 will be described in detail.
The optical waveguide 1 has an elongated strip shape, and is divided into a cladding layer 11, a core layer 13, and a cladding layer 12 from the lower side in FIG.

  Among these, in the cross section of the core layer 13, a refractive index distribution having a refractive index biased in the width direction is formed. This refractive index distribution has a region having a relatively high refractive index and a region having a relatively low refractive index, so that incident light can be confined and propagated in a region having a high refractive index. In addition, the refractive index changes continuously between the high refractive index region and the low refractive index region. Such a refractive index distribution is generally called a graded index type (GI type).

Hereinafter, an example of the refractive index distribution accompanied by such a continuous refractive index change will be described.
2A is a cross-sectional view taken along the line XX in FIG. 1, and FIG. 2B is a cross-sectional view taken along the center line C1 passing through the center in the thickness direction of the core layer 13 in the cross-sectional view taken along the line XX. It is a figure which shows an example of refractive index distribution typically.

  The core layer 13 has a refractive index distribution W including two maximum values Wm1 and Wm2 as shown in FIG. This refractive index distribution W is accompanied by a refractive index change such that the refractive index gradually decreases as the distance from each local maximum value increases. For this reason, the refractive index distribution W shown in FIG. 2B has a substantially U-shape that is convex upward (in the vicinity of the maximum value Wm2), in the vicinity of the maximum value Wm1 and in the vicinity of the maximum value Wm2. There is no.

  In the refractive index distribution W, the region having a substantially U-shape that is convex upward in this manner becomes the core portion 14 because the refractive index is relatively higher than other regions. In FIG. 2, of the two core portions 14, the core portion 141 is positioned near the maximum value Wm 1, and the core portion 142 is positioned near the maximum value Wm 2.

  On the other hand, in the region adjacent to the core part 14, the refractive index is lower than that of the core part 14, and the refractive index hardly changes. That is, the refractive index of this region is a constant value lower than each maximum value. Therefore, this region becomes the side cladding portion 15. In FIG. 2, there are three side clad parts 15, of which the one located on the left side of the core part 141 is the side clad part 151 and is located between the core part 141 and the core part 142. Is the side cladding portion 152, and the one located on the right side of the core portion 142 is the side cladding portion 153.

  The refractive index distribution W has a maximum value corresponding to the number of core portions. When there are two core portions 14 as in this embodiment, the refractive index distribution W has two maximum values, but the number of maximum values (the number of core portions 14) may be three or more.

  The plurality of maximum values are preferably substantially the same value, but may be slightly deviated. In that case, it is preferable that the amount of deviation is suppressed within 10% of the average value of the plurality of maximum values.

  The optical waveguide 1 has a long and narrow band shape, and the refractive index distribution W as described above is maintained substantially the same in the entire longitudinal direction of the optical waveguide 1.

  Along with the refractive index distribution W as described above, the core layer 13 is formed with two long core portions 14 and three side clad portions 15 adjacent to both side surfaces of the core portions 14. The Rukoto.

  More specifically, the optical waveguide 1 shown in FIG. 1 is provided with two parallel core portions 141 and 142 and three side clad portions 151, 152, and 153 arranged in parallel. As a result, the core portions 141 and 142 are respectively surrounded by the side clad portions 151, 152, and 153 and the clad layers 11 and 12 (hereinafter collectively referred to as “cladding portions”). It becomes. Since the signal light incident on each of the core parts 141 and 142 is reflected at the interface with the clad part or in the vicinity thereof, the signal light can propagate through each of the core parts 141 and 142. In addition, a dense dot is attached | subjected to each core part 14 shown in FIG. 1, and a sparse dot is attached | subjected to each side clad part 15. FIG.

  In order to cause signal light to be reflected at or near the interface between the core part 14 and the clad part, there is a refractive index difference between the maximum values Wm1 and Wm2 in the core part 14 and the refractive index of the clad part. There is a need. The maximum values Wm1 and Wm2 need only be larger than the refractive index of the cladding part, and the magnitude of the difference (refractive index difference) is not particularly limited, but is preferably 0.5% or more of the refractive index of the cladding part. And more preferably 0.8% or more. On the other hand, the upper limit value of the refractive index difference is not particularly limited, but is preferably about 5.5%. If the difference in refractive index is less than the lower limit, the effect of propagating signal light may be reduced, and even if the upper limit is exceeded, no further increase in signal light transmission efficiency can be expected.

The difference in refractive index is expressed by the following equation when the maximum refractive index (maximum values Wm1, Wm2) of the core portion 14 is n ₁ and the refractive index of the cladding portion is n ₂ .
Refractive index difference (%) = | n ₁ / n ₂ −1 | × 100

  Moreover, in the structure shown in FIG. 1, although the core part 14 is formed in linear form by planar view, you may be curving, branching, etc. in the middle, The shape is arbitrary.

  1 has a quadrangular shape (rectangular shape) such as a square or a rectangle, but this shape is not particularly limited. For example, a perfect circle, an ellipse, or an oval The shape may be a circle such as a triangle, a triangle, a pentagon, or a polygon such as a hexagon.

  The width and height of the core part 14 (thickness of the core layer 13) are not particularly limited, but each is preferably about 1 to 200 μm, more preferably about 5 to 100 μm, and about 20 to 70 μm. More preferably.

  On the other hand, the width of the side cladding portion 15 is preferably about 0.2 to 5 times the width of the core portion 14, and more preferably about 0.3 to 3 times.

  As described above, the refractive index distribution W has the maximum values Wm1 and Wm2, and has a distribution in which the refractive index continuously decreases as the distance from these maximum values increases. The optical waveguide 1 having W has an enhanced effect of confining light in the core portion 14 as compared with an optical waveguide having a so-called step index type refractive index distribution. For this reason, in the optical waveguide 1, the transmission loss can be further reduced.

  Further, the signal light propagating through the core portion 14 is concentrated and propagated in a region closer to the center portion in the core portion 14. For this reason, there is almost no difference in the propagation time for each optical path, and the waveform of the optical signal hardly changes with propagation. For example, when a pulse signal is included in the signal light, bluntness (spreading) of the pulse signal can be suppressed. As a result, the quality of optical communication can be further improved.

  Note that the refractive index continuously changing in the refractive index distribution W is a state in which the curve of the refractive index distribution W is rounded in each part and the curve is differentiable.

  Of the refractive index distribution W, the refractive index distribution in the vicinity of the maximum values Wm1 and Wm2 is preferably bilaterally symmetric. Thereby, in each core part 14, the probability that signal light will gather in the center part of the width of core part 14 will become high, and the probability that it will leak to the side clad part 15 side relatively becomes low. As a result, transmission loss in the core unit 14 can be further reduced.

  Although not shown in FIG. 2, if necessary, local maximum values smaller than local maximum values Wm1 and Wm2 may exist at positions corresponding to the side cladding portion 15 in the refractive index distribution W. .

  Such maximum values relatively smaller than the maximum values Wm1 and Wm2 do not have a high light transmission property like the core portions 141 and 142, but have a slightly higher refractive index than the surroundings, and are slightly lower. It will have optical transmission properties. As a result, the side cladding portions 151, 152, and 153 can confine transmission light leaked from the core portions 141 and 142, and can prevent ripples to other core portions. That is, since the maximum value exists in the side clad portion 15, the optical waveguide 1 can reliably suppress crosstalk.

  The constituent material (main material) of the core layer 13 as described above is not particularly limited as long as it is a material that causes the above-described difference in refractive index, but specifically, acrylic resin, methacrylic resin, polycarbonate, polystyrene, epoxy Cyclic ether resins such as polyamide resins and oxetane resins, polyamides, polyimides, polybenzoxazoles, polysilanes, polysilazanes, silicone resins, fluorine resins, urethane resins, benzocyclobutene resins, norbornene resins, etc. Various resin materials such as cyclic olefin-based resins can be used. Note that the resin material may be a composite material in which materials having different compositions are combined.

  Of these, norbornene resins are particularly preferable. The norbornene-based polymer includes, for example, ring-opening metathesis polymerization (ROMP), combination of ROMP and hydrogenation reaction, polymerization by radical or cation, polymerization using a cationic palladium polymerization initiator, and other polymerization initiators (for example, It can be obtained by all known polymerization methods such as polymerization using nickel or other transition metal polymerization initiators).

  The clad layers 11 and 12 constitute clad portions located at the lower and upper portions of the core layer 13, respectively.

  The average thickness of the clad layers 11 and 12 is preferably about 0.1 to 1.5 times the average thickness of the core layer 13 (average height of each core portion 14). More preferably, the average thickness of the clad layers 11 and 12 is not particularly limited, but is usually preferably about 1 to 200 μm, and preferably about 5 to 100 μm. More preferably, it is about 10 to 60 μm. Thereby, the function as a clad part is suitably exhibited while preventing the optical waveguide 1 from becoming unnecessarily large (thickened).

  Further, as the constituent material of the cladding layers 11 and 12, for example, the same material as the constituent material of the core layer 13 described above can be used, but a norbornene polymer is particularly preferable.

  Further, when selecting the constituent material of the core layer 13 and the constituent materials of the clad layers 11 and 12, the material may be selected in consideration of the refractive index difference between them. Specifically, in order to reliably reflect light at the boundary between the core portion 14 and the cladding layers 11 and 12, the material may be selected so that the refractive index of the constituent material of the cladding layers 11 and 12 is sufficiently small. . As a result, a sufficient refractive index difference is obtained in the thickness direction of the optical waveguide 1, and light can be prevented from leaking from the respective core portions 14 to the cladding layers 11 and 12.

  From the viewpoint of suppressing light attenuation, it is also important that the adhesiveness (affinity) between the constituent material of the core layer 13 and the constituent materials of the cladding layers 11 and 12 is high.

  The optical waveguide 1 may be laminated with a support film 2 provided on the lower surface of the cladding layer 11 and a cover film 3 provided on the upper surface of the cladding layer 12.

  Examples of the constituent material of the support film 2 and the cover film 3 include various resin materials such as polyethylene terephthalate (PET), polyolefin such as polyethylene and polypropylene, polyimide, and polyamide.

  Moreover, although each average thickness of the support film 2 and the cover film 3 is not specifically limited, It is preferable that it is about 5-200 micrometers, and it is more preferable that it is about 10-100 micrometers.

  The support film 2 and the clad layer 11 and the cover film 3 and the clad layer 12 are bonded or bonded, and as a method therefor, thermocompression bonding, bonding with an adhesive or a pressure-sensitive adhesive is used. Etc.

  Among these, as an adhesive layer, various hot-melt-adhesives (polyester type | system | group, modified olefin type | system | group) etc. are mentioned other than an acrylic adhesive, a urethane type adhesive agent, a silicone type adhesive agent, for example. Moreover, as a thing with especially high heat resistance, thermoplastic polyimide adhesive agents, such as a polyimide, a polyimide amide, a polyimide amide ether, a polyester imide, a polyimide ether, are used preferably.

  Moreover, although the average thickness of an contact bonding layer is not specifically limited, It is preferable that it is about 1-100 micrometers, and it is more preferable that it is about 5-60 micrometers.

<Optical waveguide manufacturing method>
Next, an example of a method for manufacturing the optical waveguide 1 described above will be described.

(First manufacturing method)
First, the 1st manufacturing method (1st Embodiment of the manufacturing method of the optical waveguide of this invention) of the optical waveguide 1 is demonstrated.

  3, 4, and 8 to 10 are views for explaining a first manufacturing method of the optical waveguide 1 shown in FIG. 1. In the following description, the upper side in FIGS. 3, 4, and 8 to 10 is referred to as “upper”, and the lower side is referred to as “lower”.

  The first manufacturing method of the optical waveguide 1 includes: [1] a step of supplying the core layer forming composition 900 in a layer form on the support substrate 951 to obtain the layer 910; and [2] active radiation on a part of the layer 910. The step of generating a difference in refractive index by irradiating and obtaining the optical waveguide 1 is provided.

Hereinafter, each process will be described sequentially.
[1] First, a core layer forming composition 900 is prepared.

  The core layer forming composition 900 contains a polymer 915 and an additive 920.

  Next, the core layer forming composition 900 is applied on the support substrate 951 to form a liquid film (see FIG. 3A). Then, the support substrate 951 is placed on the level table to flatten the liquid film and evaporate (desolvent) the solvent. Thereby, a layer 910 shown in FIG. 3B is obtained (first step).

  For the support substrate 951, for example, a silicon substrate, a silicon dioxide substrate, a glass substrate, a polyethylene terephthalate (PET) film, or the like is used.

  Examples of the coating method for forming the liquid film include a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, and a die coating method.

  In the resulting layer 910, the polymer (matrix) 915 is present substantially uniformly and randomly, and the additive 920 is substantially uniformly and randomly dispersed in the polymer 915. Thereby, the additive 920 is substantially uniformly and randomly dispersed in the layer 910.

  The average thickness of the layer 910 is appropriately set according to the thickness of the core layer 13 to be formed, and is not particularly limited, but is preferably about 5 to 300 μm, and more preferably about 10 to 200 μm.

(polymer)
The polymer 915 serves as a base polymer for the core layer 13.

  The polymer 915 has sufficiently high transparency (colorless and transparent), and the refractive index changes due to isomerization or dimerization of a part of the chemical structure by irradiation with actinic radiation described later. Things are used.

  Specifically, the polymer 915 has a main chain and a side chain that is branched from the main chain and includes a chemical structure (photoisomerization group / photodimerization group) that can be photoisomerized or photodimerized. .

  Examples of such a polymer 915 include cyclic olefin resins such as norbornene resins and benzocyclobutene resins, acrylic ethers, methacrylic resins, polycarbonates, polystyrenes, cyclic ethers such as epoxy resins and oxetane resins. Resins, polyamides, polyimides, polybenzoxazoles, silicone resins, fluorine resins, urethane resins, etc., and a combination of one or more of these (polymer alloy, polymer blend (mixture), Copolymer) and the like.

  Among these, those mainly composed of cyclic olefin resins are preferable. By using a cyclic olefin resin as the polymer 915, the optical waveguide 1 having excellent light transmission performance and heat resistance can be obtained.

  The cyclic olefin-based resin may be unsubstituted or may have hydrogen substituted with other groups.

  Examples of the cyclic olefin resins include norbornene resins and benzocyclobutene resins.

  Among these, it is preferable to use a norbornene-based resin from the viewpoints of heat resistance and transparency. Moreover, since norbornene-type resin has high hydrophobicity, the optical waveguide 1 which cannot produce the dimensional change by water absorption etc. easily can be obtained.

  The norbornene-based resin may be either one having a single repeating unit (homopolymer) or one having two or more norbornene-based repeating units (copolymer).

As such a norbornene-based resin, for example,
(1) addition (co) polymer of norbornene type monomer obtained by addition (co) polymerization of norbornene type monomer,
(2) an addition copolymer of a norbornene monomer and ethylene or α-olefins,
(3) an addition polymer such as an addition copolymer of a norbornene-type monomer and a non-conjugated diene and, if necessary, another monomer;
(4) a ring-opening (co) polymer of a norbornene-type monomer, and a resin obtained by hydrogenating the (co) polymer if necessary,
(5) a ring-opening (co) polymer of a norbornene-type monomer and ethylene or α-olefins, and a resin obtained by hydrogenating the (co) polymer if necessary,
(6) Ring-opening copolymers such as norbornene-type monomers and non-conjugated dienes, or other monomers, and polymers obtained by hydrogenating the copolymer as necessary. Examples of these polymers include random copolymers, block copolymers, and alternating copolymers.

  These norbornene resins include, for example, ring-opening metathesis polymerization (ROMP), combination of ROMP and hydrogenation reaction, polymerization by radical or cation, polymerization using cationic palladium polymerization initiator, other polymerization initiators ( For example, it can be obtained by any known polymerization method such as polymerization using a polymerization initiator of nickel or another transition metal).

  Among these, the norbornene-based resin is preferably an addition (co) polymer having at least one repeating unit represented by the following structural formula B. Since the addition (co) polymer is rich in transparency, heat resistance, and flexibility, for example, after the optical waveguide 1 is formed, an electrical component or the like may be mounted on the optical waveguide 1 via solder. This is because even in such a case, high heat resistance, that is, reflow resistance can be imparted to the optical waveguide 1.

  Such a norbornene-based polymer is suitably synthesized by using, for example, a norbornene-based monomer.

  Further, when the optical waveguide 1 is incorporated into various products, the product may be used in an environment of about 80 ° C., for example. Even in such a case, an addition (co) polymer is preferable from the viewpoint of ensuring heat resistance.

  Among them, the norbornene-based resin includes a norbornene repeating unit containing a photoisomerization group / photodimerization group described later, a norbornene repeating unit having a substituent containing a polymerizable group, and a substituent containing an aryl group. Those containing norbornene repeating units are preferred.

  As the repeating unit of norbornene having a substituent containing a polymerizable group, the repeating unit of norbornene having a substituent containing an epoxy group, the repeating unit of norbornene having a substituent containing a (meth) acryl group, and an alkoxysilyl group At least one of the repeating units of norbornene having a substituent containing is preferable. These polymerizable groups are preferable because of their high reactivity among various polymerizable groups.

  Moreover, if the thing containing 2 or more types of repeating units of norbornene containing such a polymeric group is used, both flexibility and heat resistance can be aimed at.

  On the other hand, by including a norbornene repeating unit having a substituent containing an aryl group, dimensional change due to water absorption can be more reliably prevented by the extremely high hydrophobicity derived from the aryl group.

  Further, the norbornene-based resin preferably includes an alkylnorbornene repeating unit. The alkyl group may be linear or branched.

  By including the repeating unit of alkyl norbornene, the norbornene-based resin has high flexibility, and thus can provide high flexibility (flexibility).

  A norbornene-based resin containing an alkylnorbornene repeating unit is also preferable because of its excellent transmittance with respect to light in a specific wavelength region (particularly, a wavelength region near 850 nm).

  Specific examples of the norbornene-based resin including the norbornene repeating unit as described above include hexyl norbornene homopolymer, phenylethyl norbornene homopolymer, benzyl norbornene homopolymer, hexyl norbornene and phenylethyl norbornene copolymer, hexyl norbornene. And a copolymer of benzylnorbornene and the like.

  Among these, as the repeating unit of norbornene including alkyl norbornene, those represented by the following formulas (1) to (4) and (8) to (10) are preferable.

(In Formula (1), R ₁ represents an alkyl group having 1 to 10 carbon atoms, a represents an integer of 0 to 3, b represents an integer of 1 to 3, and p ₁ / q ₁ is 20 or less.)

  The norbornene resin containing the repeating unit of the formula (1) can be produced as follows.

(1) is obtained by dissolving norbornene having R ₁ and norbornene having an epoxy group in the side chain in toluene and solution polymerization using Ni compound (A) as a catalyst.

  In addition, the manufacturing method of norbornene which has an epoxy group in a side chain is as (i) (ii), for example.

(I) Synthesis of norbornene methanol (NB—CH ₂ —OH) CPD (cyclopentadiene) and α-olefin (CH ₂ ═CH—CH ₂ —OH) produced by cracking of DCPD (dicyclopentadiene) are heated under high temperature and high pressure. React.

(Ii) Synthesis of epoxy norbornene It is formed by the reaction of norbornene methanol and epichlorohydrin.

  In formula (1), when b is 2 or 3, epichlorohydrin in which the methylene group is an ethylene group, a propylene group or the like is used.

Among the norbornene-based resins containing the repeating unit represented by the formula (1), particularly, R ₁ is an alkyl group having 4 to 10 carbon atoms from the viewpoint of achieving both flexibility and heat resistance. And a compound in which a and b are each 1, for example, a copolymer of butyl norbornene and methyl glycidyl ether norbornene, a copolymer of hexyl norbornene and methyl glycidyl ether norbornene, a copolymer of decyl norbornene and methyl glycidyl ether norbornene, and the like.

(In Formula (2), R ₂ represents an alkyl group having 1 to 10 carbon atoms, R ₃ represents a hydrogen atom or a methyl group, c represents an integer of 0 to 3, and p ₂ / q _2. Is 20 or less.)

A norbornene-based resin containing a repeating unit of the formula (2) is prepared by dissolving norbornene having R ₂ and norbornene having an acrylic and methacrylic group in the side chain in toluene, and using the Ni compound (A) described above as a catalyst. It can be obtained by polymerization.

Among the norbornene-based resins containing the repeating unit represented by the formula (2), in particular, R ₂ is an alkyl group having 4 to 10 carbon atoms from the viewpoint of achieving both flexibility and heat resistance, and c Are compounds such as butyl norbornene and 2- (5-norbornenyl) methyl acrylate copolymer, hexyl norbornene and 2- (5-norbornenyl) methyl acrylate copolymer, decyl norbornene and 2- (acrylic acid 2- ( Copolymers with 5-norbornenyl) methyl are preferred.

(In Formula (3), R ₄ represents an alkyl group having 1 to 10 carbon atoms, each X ₃ independently represents an alkyl group having 1 to 3 carbon atoms, and d represents 0 to 3 carbon atoms. Represents an integer, and p ₃ / q ₃ is 20 or less.)

The resin containing the repeating unit of the formula (3) is obtained by dissolving norbornene having R ₄ and norbornene having an alkoxysilyl group in the side chain in toluene, and performing solution polymerization using the above-described Ni compound (A) as a catalyst. Can be obtained at

Among the norbornene-based polymers represented by the formula (3), in particular, a compound in which R ₄ is an alkyl group having 4 to 10 carbon atoms, d is 1 or 2, and X ₃ is a methyl group or an ethyl group, For example, a copolymer of butylnorbornene and norbornenylethyltrimethoxysilane, a copolymer of hexylnorbornene and norbornenylethyltrimethoxysilane, a copolymer of decylnorbornene and norbornenylethyltrimethoxysilane, butylnorbornene and triethoxysilyl Copolymer of norbornene, copolymer of hexyl norbornene and triethoxysilyl norbornene, copolymer of decyl norbornene and triethoxysilyl norbornene, copolymer of butyl norbornene and trimethoxysilyl norbornene, hex Copolymer of norbornene and trimethoxysilyl norbornene, copolymers, etc. of decyl norbornene and trimethoxysilyl norbornene are preferred.

(In formula (4), R ₅ represents an alkyl group having 1 to 10 carbon atoms, and A ₁ and A ₂ each independently represent a substituent represented by the following formulas (5) to (7). (However, they are not the same substituent at the same time, and p ₄ / (q ₄ + r) is 20 or less.)

The resin containing the repeating unit of the formula (4) is obtained by dissolving norbornene having R ₅ and norbornene having A ₁ and A ₂ in the side chain in toluene, and performing solution polymerization using Ni compound (A) as a catalyst. Can be obtained at

(In formula (5), e represents an integer of 0 to 3, and f represents an integer of 1 to 3.)

(In formula (6), R ₆ represents a hydrogen atom or a methyl group, and g represents an integer of 0 to 3.)

(Equation (7) in, _{X 4} each independently represents an alkyl group having 1 to 3 carbon atoms, h is. Represents an integer of 0 to 3)

  In addition, as norbornene-type resin containing the repeating unit represented by Formula (4), for example, any of butyl norbornene, hexyl norbornene, or decyl norbornene, 2- (5-norbornenyl) methyl acrylate, and norbornenyl ethyl A terpolymer with either trimethoxysilane, triethoxysilyl norbornene or trimethoxysilyl norbornene, any of butyl norbornene, hexyl norbornene or decyl norbornene, 2- (5-norbornenyl) methyl acrylate, and methyl glycidyl ether norbornene Terpolymer, butyl norbornene, hexyl norbornene or decyl norbornene, methyl glycidyl ether norbornene, norbornenyl ethyl trimethoxysilane , Terpolymers, etc. and either triethoxysilyl norbornene or trimethoxysilyl norbornene.

(In formula (8), R ₇ represents an alkyl group having 1 to 10 carbon atoms, R ₈ represents a hydrogen atom, a methyl group or an ethyl group, Ar represents an aryl group, and X ₁ represents oxygen. X ₂ represents a carbon atom or a silicon atom, i represents an integer of 0 to 3, j represents an integer of 1 to 3, and p ₅ / q ₅ is 20 or less. is there.)

The resin containing the repeating unit of the formula (8) includes norbornene having R ₇ and norbornene containing — (CH ₂ ) _i —X ₁ —X ₂ (R ₈ ) _{3 -j} (Ar) _j in the side chain. It can be obtained by dissolving in toluene and solution polymerization using a Ni compound as a catalyst.

Of the norbornene resins containing the repeating unit represented by the formula (8), those in which X ₁ is an oxygen atom, X ₂ is a silicon atom, and Ar is a phenyl group are preferable.

Further, particularly from the viewpoint of flexibility, heat resistance and refractive index control, R ₇ is an alkyl group having 4 to 10 carbon atoms, X ₁ is an oxygen atom, X ₂ is a silicon atom, Ar is a phenyl group, R Compounds in which ₈ is a methyl group, i is 1 and j is 2, for example, a copolymer of butylnorbornene and diphenylmethylnorbornenemethoxysilane, a copolymer of hexylnorbornene and diphenylmethylnorbornenemethoxysilane, decylnorbornene and diphenylmethylnorbornenemethoxysilane And a copolymer thereof are preferred.
Specifically, it is preferable to use the following norbornene resin.

(R ₇ , p ₅ , q ₅ , and i in formula (9) are the same as in formula (8).)

From the viewpoint of flexibility, heat resistance, and refractive index control, in Formula (8), R ₇ is an alkyl group having 4 to 10 carbon atoms, X ₁ is a methylene group, X ₂ is a carbon atom, and Ar is A compound having a phenyl group, R ₈ is a hydrogen atom, i is 0, and j is 1, for example, a copolymer of butylnorbornene and phenylethylnorbornene, a copolymer of hexylnorbornene and phenylethylnorbornene, a decylnorbornene and phenylethylnorbornene It may be a copolymer or the like.
Further, the following may be used as the norbornene resin.

(In Formula (10), R ₁₀ represents an alkyl group having 1 to 10 carbon atoms, R ₁₁ represents an aryl group, and k is 0 or more and 4 or less. P ₆ / q ₆ is 20 or less. is there.)

_{Further, p 1 / q 1 ~p 3} / q 3, p 5 / q 5, p 6 / q 6 or _{p 4 / (q 4 + r} ) may or if 20 or less, 15 or less Preferably, about 0.1-10 is more preferable. Thereby, the effect including the repeating unit of multiple types of norbornene is exhibited.

  On the other hand, the polymer 915 may be an acrylic resin, a methacrylic resin, an epoxy resin, a polyimide, a silicone resin, a fluorine resin, polysilane, polyurethane, or the like as described above.

  Among these, examples of acrylic resins and methacrylic resins include poly (methyl acrylate), poly (methyl methacrylate), poly (epoxy acrylate), poly (epoxy methacrylate), poly (amino acrylate), and poly (amino methacrylate). , Polyacrylic acid, polymethacrylic acid, poly (isocyanate acrylate), poly (isocyanate methacrylate), poly (cyanate acrylate), poly (cyanate methacrylate), poly (thioepoxy acrylate), poly (thioepoxy methacrylate) , Poly (allyl acrylate), poly (allyl methacrylate), acrylate / epoxy acrylate copolymer (copolymer of methyl methacrylate and glycidyl methacrylate), styrene / epoxy Acrylate copolymer and the like, these one or more composite material is used.

  Examples of the epoxy resin include alicyclic epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin having a biphenyl skeleton, naphthalene ring-containing epoxy resin, Dicyclopentadiene type epoxy resin having cyclopentadiene skeleton, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, triphenylmethane type epoxy resin, aliphatic epoxy resin, triglycidyl isocyanurate, etc. Of these, one or more of these composite materials are used.

  Further, the polyimide is not particularly limited as long as it is a resin obtained by ring-closing and curing (imidizing) a polyamic acid which is a polyimide resin precursor.

  As the polyamic acid, for example, it can be obtained as a solution by reacting tetracarboxylic dianhydride and diamine in an equimolar ratio in N, N-dimethylacetamide.

  Among these, examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2-bis (2,3-di Carboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3- Hexafluoropropane dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) And sulfonic acid dianhydrides.

  On the other hand, examples of the diamine include m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, and 3,3'-diaminodiphenyl. Sulfone, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,4-diaminotoluene, 2,6-diaminotoluene, diaminodiphenylmethane, 4,4′-diamino-2,2-dimethylbiphenyl, 2,2-bis (trifluoromethyl)- 4,4′-diaminobiphenyl and the like can be mentioned.

  Examples of the silicone resin include silicone rubber and silicone elastomer. These silicone resins are obtained by reacting a silicone rubber monomer or oligomer with a curing agent.

  Examples of the silicone rubber monomer or oligomer include those containing a methylsiloxane group, an ethylsiloxane group, or a phenylsiloxane group.

  As the silicone rubber monomer or oligomer, for example, those obtained by introducing a functional group such as an epoxy group, a vinyl ether group or an acrylic group are preferably used in order to impart photoreactivity.

  In addition, as the fluorine-based resin, for example, a polymer obtained from a monomer having a fluorine-containing aliphatic ring structure, a polymer obtained by cyclopolymerizing a fluorine-containing monomer having two or more polymerizable unsaturated bonds, Examples thereof include a polymer obtained by copolymerizing a fluorine-containing monomer and a radical polymerizable monomer.

  Examples of the fluorinated aliphatic ring structure include perfluoro (2,2-dimethyl-1,3-dioxole), perfluoro (4-methyl-1,3-dioxole), and perfluoro (4-methoxy-1,3-dioxole). ) And the like.

  Examples of the fluorine-containing monomer include perfluoro (allyl vinyl ether) and perfluoro (butenyl vinyl ether).

  Examples of the radical polymerizable monomer include tetrafluoroethylene, chlorotrifluoroethylene, perfluoro (methyl vinyl ether) and the like.

  Any polysilane may be used as long as the main chain is a polymer composed only of Si atoms. The main chain may be linear or branched. In addition to Si atoms, organic substituents such as hydrogen atoms, hydrocarbon groups, and alkoxy groups are bonded to Si atoms in the polysilane.

  Among these, examples of the hydrocarbon group include an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen, an aromatic hydrocarbon group having 6 to 14 carbon atoms, and the like.

  Specific examples of the aliphatic hydrocarbon group include a chain hydrocarbon group such as methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, trifluoropropyl group, and nonafluorohexyl group, Examples thereof include alicyclic hydrocarbon groups such as a cyclohexyl group and a methylcyclohexyl group.

  Specific examples of the aromatic hydrocarbon group include a phenyl group, a p-tolyl group, a biphenyl group, and an anthracyl group.

  As an alkoxy group, a C1-C8 thing is mentioned, Specifically, a methoxy group, an ethoxy group, a phenoxy group, an octyloxy group etc. are mentioned.

  As the polyurethane, any polymer may be used as long as it is a polymer containing a urethane bond (—O—CO—NH—) in the main chain. And a urethane-urea copolymer containing a urethane bond and a urea bond (—NH—CO—NH—, —NH—CO—N═, or —NH—CO—N <) in the main chain, etc. Also good.

  In order to obtain a polymer 915 having a relatively high refractive index regardless of the composition, a monomer having an aromatic ring (aromatic group), a nitrogen atom, a bromine atom or a chlorine atom in the molecular structure is generally used. The polymer 915 is synthesized (polymerized). On the other hand, in order to obtain a polymer 915 having a relatively low refractive index, a monomer having an alkyl group, a fluorine atom or an ether structure (ether group) is generally selected in the molecular structure, and the polymer 915 is synthesized ( Polymerization).

  As the norbornene-based resin having a relatively high refractive index, a resin containing a repeating unit of aralkylnorbornene is preferable. Such norbornene-based resins have a particularly high refractive index.

  Examples of the aralkyl group (arylalkyl group) of the aralkylnorbornene repeating unit include benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, naphthylethyl group, naphthylpropyl group, fluorenylethyl group, fluorene group, and the like. Examples thereof include a nylpropyl group, and a benzyl group and a phenylethyl group are particularly preferable. A norbornene-based resin having such a repeating unit is preferable because it has a very high refractive index.

  In addition, as described above, the polymer 915 as described above can be partly photoisomerized or photodimerized by irradiation with actinic radiation, whereby the refractive index can be changed.

  As described above, the polymer 915 has a main chain and side chains that are branched from the main chain and partially include a chemical structure that can be photoisomerized or photodimerized by irradiation with actinic radiation. That is, the polymer 915 has a repeating unit containing a photoisomerization group / photodimerization group. Since a part of the chemical structure undergoes photoisomerization or photodimerization to change the refractive index of the polymer 915, the polymer 915 may form a refractive index difference depending on the presence or absence of active radiation irradiation or the difference in accumulated light quantity. it can.

  Examples of the chemical structure that is partially photoisomerized or photodimerized by irradiation with actinic radiation include those containing an N═N group, a C═C group, a C═N group, a C═O group, and the like. These chemical structures cause cis-trans isomerization and decarboxylation (hereinafter photoisomerization) upon irradiation with actinic radiation, or bonds between adjacent double bonds (above photodimerization). ) May occur. As a result, the refractive index of the polymer 915 changes before and after irradiation with actinic radiation. Since the degree of isomerization and dimerization varies depending on the integrated amount of actinic radiation, the refractive index in the polymer 915 can be freely controlled by appropriately setting the presence or absence of actinic radiation and the integrated amount of light. it can.

  Specific examples of such chemical structures include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, N = N groups, maleimide groups, indene groups, coumarin groups, cinnamates. Group, polyene group, stilbene group, stilbazole group, stilbazolium group, cinnamoyl group, hemithioindigo group, C═C group such as chalcone group, C═N group such as aromatic Schiff base, aromatic hydrazone structure, benzophenone Groups, C = O groups such as anthraquinone groups, ester groups such as allyl ester groups, acylphenol structures, and the like, and at least one of these is used. In particular, at least one of an azobenzene group, a maleimide group, a coumarin group, a cinnamoyl group, and an indene group is preferably used. For example, when the polymer 915 is a norbornene polymer, an azobenzene norbornene polymer, a maleimide norbornene polymer, a coumarin norbornene polymer, a cinnamoyl norbornene polymer, or an indene norbornene polymer is preferably used. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, or a halogenated alkyl group. .

  In addition, the norbornene repeating unit having such a chemical structure includes, in particular, a maleimide-based norbornene represented by the following formula (11), a coumarin-based norbornene represented by the formula (12), and a cinnamoyl represented by the formula (13). A system norbornene and an indene system norbornene represented by the formula (14) are preferable.

(X in Formula (11) represents an alkylene group having 1 to 3 carbon atoms.)

In (Equation (11) ~ (14), s is the degree of polymerization of alkyl norbornene repeating units p (e.g., _{p 1, p 2} in formula (2), the formula (3 in the formula (1)) p _{3, p 4} in formula (4), the equation (8), between the _{p 6)} in _{p 5,} the formula (10) in (9), p / s satisfies the relationship of 20 or less .)
Further, p / s is preferably 15 or less, more preferably about 0.1 to 10.

  In addition, how to change the refractive index by photoisomerization or photodimerization differs depending on the type of chemical structure. For example, when the refractive index of the layer 910 decreases with photoisomerization or photodimerization, a region having a lower refractive index is formed as the integrated light amount of the active radiation 930 increases. Therefore, the central portion of the irradiation region of the active radiation 930 is mainly the side cladding portion 15. On the other hand, when the refractive index of the layer 910 increases with photoisomerization or photodimerization, a region having a higher refractive index is formed as the integrated light amount of the active radiation 930 is increased. Therefore, the central portion of the irradiation region of the active radiation 930 is mainly the core portion 14.

  Here, the main chain of the polymer 915 to which the above-described chemical structure is bonded includes, in particular, polymers of monocyclic monomers such as cyclohexene and cyclooctene, norbornene, norbornadiene, dicyclopentadiene, dihydrodicyclopentadiene, tetra Examples thereof include cyclic olefin resins such as polymers of polycyclic monomers such as cyclododecene, tricyclopentadiene, dihydrotricyclopentadiene, tetracyclopentadiene, and dihydrotetracyclopentadiene. Among these, one or more cyclic olefin resins selected from polymers of polycyclic monomers are preferably used. Thereby, the chemical structure is reliably bonded to the main chain, and the heat resistance of the resin can be improved.

  The polymer 915 includes any repeating unit (second repeating unit) other than the repeating unit (first repeating unit) including the above-described photoisomerizable group / photodimerized group. In addition, the combination of the first repeating unit and the second repeating unit, the combination of the first repeating units, and the combination of the second repeating units are not limited.

  Moreover, well-known forms, such as random polymerization and block polymerization, can be applied as the polymerization form. For example, specific examples of polymerization of norbornene type monomers include (co) polymers of norbornene type monomers, copolymers of norbornene type monomers and other copolymerizable monomers such as α-olefins, A combined hydrogenated product corresponds to a specific example. These cyclic olefin resins can be produced by a known polymerization method. The polymerization methods include an addition polymerization method and a ring-opening polymerization method, and among them, the cyclic olefin resin obtained by the addition polymerization method. (In particular, norbornene-based resins) are preferable (that is, addition polymers of norbornene-based compounds). Thereby, it is excellent in transparency, heat resistance, and flexibility.

  Although content of the said chemical structure is not specifically limited, It is preferable that it is 10-80 weight% in the polymer 915, and it is more preferable that it is especially 20-60 weight%. When the content is within the above range, both flexibility and refractive index modulation function (effect of changing the refractive index difference) are particularly excellent.

  In addition, the width | variety which changes a refractive index can be extended by increasing content of the said chemical structure.

(Additive)
Examples of the additive 920 include a catalyst precursor, a co-catalyst, an antioxidant, an ultraviolet absorber, a light stabilizer, a silane coupling agent, a coating surface improver, a thermal polymerization inhibitor, a leveling agent, a surfactant, and coloring. Agents, storage stabilizers, plasticizers, lubricants, fillers, inorganic particles, deterioration inhibitors, wettability improvers, antistatic agents and the like.

  The content of the additive 920 in the core layer forming composition 900 is preferably 0.01% by weight or more, more preferably 0.5% by weight or more, and 1% by weight or more. Further preferred. In addition, it is preferable that an upper limit is 5 weight% or less.

  Note that the layer 910 as described above potentially has a refractive index adjustment capability capable of forming a refractive index difference by irradiating the active radiation 930 through the mask 935.

  Therefore, if a large number of layers 910 are manufactured and stored, and then the active radiation 930 is irradiated to the required number, the optical waveguide 1 can be easily manufactured, which is useful from the viewpoint of manufacturing efficiency. It is.

  [2] Next, a mask (masking) 935 in which an opening (transmission portion) 9351 is formed is prepared, and the layer 910 is irradiated with active radiation 930 through the mask 935 (see FIG. 4).

  The mask 935 includes a shielding portion 9350 and an opening 9351 provided in a part of the shielding portion 9350. Here, the opening 9351 does not uniformly transmit the active radiation 930 as a whole, but is configured so that the transmittance is partially different. Such a mask 935 is also called a gray tone mask.

  The mask 935 is smaller than the size of the layer 910 in a plan view, and moves relative to the layer 910 to scan the layer 910 with the active radiation 930 that has passed through the opening 9351. Can do. When the actinic radiation 930 is scanned, a refractive index difference is formed in the locus, and the core portion 14 and the side cladding portion 15 are formed. According to such a method, the optical waveguide 1 having a graded index type or a similar refractive index distribution W can be efficiently manufactured simply by irradiating the active radiation 930 through the mask 935. Moreover, since it is easy to accurately control the irradiation position when irradiating the active radiation 930, the accuracy of the formation position of the core portion 14 and the side cladding portion 15 can be easily increased as a result. Therefore, it is possible to easily increase the number of channels and increase the density of the optical waveguide 1 while reliably suppressing a decrease in transmission efficiency and occurrence of crosstalk.

  FIG. 5 is a diagram showing the configuration of the mask 935. In the following description, an example in which the refractive index of the polymer 915 decreases with irradiation of the active radiation 930 will be described as an example.

  The opening 9351 shown in FIG. 5A is rectangular in plan view. Then, when the center line C2 passing through the midpoint of the long side of the opening 9351 and perpendicular to the long side is drawn, the transmittance of the opening 9351 is set to gradually decrease as the distance from the vicinity of the center line C2 increases.

  FIG. 5B is a diagram showing a transmittance distribution for each position of the long side of the opening 9351. The transmittance of the opening 9351 is the largest in the vicinity of the center line C2, and continuously decreases toward both ends of the opening 9351.

  When the active radiation 930 passes through the opening 9351 having such a transmittance distribution T, a predetermined intensity (illuminance) distribution is generated in the active radiation 930 transmitted according to the transmittance distribution T. When the layer 910 is irradiated with the active radiation 930 in which the intensity distribution is generated, it is reflected in the distribution of the integrated light amount, and finally, a refractive index distribution is formed in the layer 910. Therefore, the transmittance distribution T of the opening 9351 may be determined according to the shape of the target refractive index distribution W.

  FIG. 6 is a plan view showing how the mask 935 is scanned while irradiating the layer 910 with active radiation 930 in the first manufacturing method.

  The mask 935 is scanned so that the center line C2 of the opening 9351 is along the extending direction of the side clad portion 15 to be formed (to be along the center line R1 in FIG. 6). In addition, the source of the actinic radiation 930 is also scanned corresponding to the scanning of the mask 935. As a result, the active radiation 930 that has passed through the opening 9351 is also scanned with respect to the layer 910, and the integrated light amount of the active radiation 930 becomes the largest on or near the center line R1 of the passage path of the active radiation 930.

  In FIG. 6A, the mask 935 is scanned from the bottom to the top of the figure. In the first trajectory 931 through which the mask 935 has passed, the refractive index decreases, and the side clad portions 15 are formed on both sides of the center line R1.

  Next, the mask 935 is scanned from the upper side to the lower side so as to be adjacent to the first locus 931 (see FIG. 6B). Even in the second trajectory 932 through which the mask 935 has passed, the refractive index also decreases, and the side cladding portions 15 are formed on both sides of the center line R2.

  Then, on the boundary line B1 between the first trajectory 931 and the second trajectory 932, the integrated light quantity of the active radiation is smaller than that in the vicinity, so that the refractive index is least decreased. Therefore, the refractive index is relatively high in this region. As a result, the maximum value of the refractive index is formed at the boundary line B1, and the core portions 14 are formed on both sides of the boundary line B1. The core portion 14 is formed with a refractive index distribution in which the refractive index gradually decreases with distance from the boundary line B1.

  Next, the mask 935 is scanned from the lower side to the upper side so as to be adjacent to the second locus 932 (see FIG. 6C). Even in the third locus 933 through which the mask 935 has passed, the refractive index also decreases, and the side clad portions 15 are formed on both sides of the center line R3.

  Here, also on the boundary line B2 between the second locus 932 and the third locus 933, the decrease in the refractive index is small as on the boundary line B1. Therefore, the refractive index is relatively high in this region. As a result, the maximum value of the refractive index is also formed on the boundary line B2, and the core portions 14 are formed on both sides of the boundary line B2. The core portion 14 also has a refractive index distribution in which the refractive index gradually decreases as the distance from the boundary line B2 increases.

  As described above, the refractive index distribution W described above is formed in the layer 910. Then, the core layer 13 having the refractive index distribution W is formed (see FIG. 8).

  FIG. 7 shows the relationship between the position on the YY line cross section shown in FIG. 6 and the transmittance of active radiation that passes through the mask, the relationship between the position on the YY line cross section and the integrated light quantity, and the YY line cross section. It is a figure which shows the relationship between the position in and the refractive index of the layer 910 after irradiation of actinic radiation.

  In the first trajectory 931, the second trajectory 932, and the third trajectory 933 described above, according to the transmittance distribution T as shown in FIG. 7A in the opening 9351 of the mask 935, FIG. A cumulative light quantity distribution L as shown in FIG. As described above, the integrated light amount is the largest in the vicinity of the center lines R1, R2, and R3, and continuously decreases as the distance from the center lines R1, R2, and R3 increases.

  The refractive index distribution W as shown in FIG. 7C is formed in the layer 910 according to the integrated light quantity distribution L, and the core layer 13 is finally formed.

  The shape of the refractive index distribution W can be approximated by a shape obtained by vertically inverting the integrated light quantity distribution L. If this approximation is used, the shape of the integrated light quantity distribution L that can form the refractive index distribution W of the target shape, and thus the optimum transmittance distribution T in the opening 9351 of the mask 935 that realizes it can be easily determined. be able to.

  Further, the transmittance distribution T in the opening 9351 is preferably a distribution that satisfies a line-symmetrical relationship with respect to the center line C2. Thereby, the shape of the integrated light quantity distribution L also satisfies the line-symmetrical relationship with respect to the center lines R1, R2, and R3. As a result, the shape of the refractive index distribution W also has the center line R1. , R2, and R3 have a shape that satisfies a line-symmetrical relationship. The optical waveguide 1 having the refractive index distribution W having such a shape can reliably confine the signal light in the central portion of the core portion 14 and has high transmission efficiency.

  The actinic radiation 930 is appropriately selected according to the binding energy of the chemical bond to be photoisomerized and photodimerized. For example, in addition to visible light, ultraviolet light, infrared light, laser light, electron beam, X-ray, etc. Can also be used.

  Among these, the actinic radiation is preferably one having a peak wavelength in a wavelength range of 200 to 450 nm (mainly classified as ultraviolet rays). By using actinic radiation having such characteristics, it is possible to selectively and efficiently perform photoisomerization and photodimerization of a target chemical bond with many of the polymers 915 used in the present invention.

Further, the integrated light quantity of the actinic radiation 930 is preferably in the range of about 0.01~9J / cm ^2, more preferably about ^{0.05~6J / cm 2, 0.05~3J / cm} 2 of about More preferably.

  In addition, with the active radiation 930, it is preferable that the intensity (illuminance) distribution is uniform before reaching the mask 935. Thereby, the shape of the integrated light quantity distribution L can be determined only by the transmittance distribution T in the opening 9351 of the mask 935, and the shape of the refractive index distribution W can be finally determined. As a result, the optical waveguide 1 having the desired refractive index distribution W can be easily manufactured.

  Further, the planar view shape of the opening 9351 of the mask 935 is preferably a shape in which the lengths of the components parallel to the respective center lines R1, R2, and R3 are uniform throughout. With such a shape, the transmittance distribution T at the opening 9351 is easily reflected directly on the shape of the integrated light quantity distribution L, and the optical waveguide 1 having the desired refractive index distribution W can be easily manufactured. it can.

  The refractive index distribution W thus formed has a certain correlation with the distribution of the abundance ratio of the chemical structure photoisomerized or photodimerized with the irradiation of the active radiation 930. Therefore, by measuring the concentration distribution of this chemical structure in the core layer 13, the shape of the refractive index distribution W of the core layer 13 can be indirectly specified.

  The concentration of the chemical structure can be measured using, for example, FT-IR, TOF-SIMS line analysis, surface analysis, or the like.

  The shape of the refractive index distribution W can also be directly specified by applying a measuring method such as a refractive near field method or a differential interference method to the core layer 13.

  After the irradiation with the actinic radiation 930, the core layer 13 is heat-treated as necessary. Thereby, the formed refractive index distribution W is fixed, and the durability of the core layer 13 is improved.

  Note that when the exit surface of the active radiation 930 is sufficiently large and a plurality of openings 9351 are formed in the mask 935, the first locus 931, the second locus 932, and the third locus 933 can be compared. Irradiation with actinic radiation 930 can be performed by one scan. Thereby, the optical waveguide 1 can be manufactured more efficiently.

  Further, when the length of the component parallel to the center line C2 in the opening 9351 is longer than the length of the side cladding portion 15 to be formed, the actinic radiation 930 may be irradiated without scanning the mask 935. In this case, the source of the active radiation 930 may be scanned with respect to the layer 910 and the mask 935, and may be fixed when the exit surface of the active radiation 930 is sufficiently large.

  Here, in the mask 935 shown in FIG. 5, the opening 9351 is made of a material that can transmit the active radiation 930, and the other portion (shielding portion 9350) is made of a material that can shield the active radiation 930. Yes.

  As described above, the aperture 9351 is configured such that the transmittance of the active radiation 930 is not uniform but partially different. Such a deviation in the transmittance distribution is realized by some means provided in the opening 9351.

Hereinafter, these means will be described.
FIG. 11 is an example of a plan view and a cross-sectional view of the mask shown in FIG.

  A mask 935 shown in FIG. 11A is made of a material in which the shielding portion 9350 can shield the active radiation 930, and is provided on the transparent substrate 9351 a and a transparent substrate 9351 a provided so as to cover the opening 9351. And a shielding film 9351b partially different in thickness.

  As shown in FIG. 11B, the shielding film 9351b is configured to have the smallest thickness in the vicinity of the center line C2 of the mask 935, and the thickness of the shielding film 9351b gradually increases as the distance from the center line C2 increases. ing. Thereby, in the shielding film 9351b, a transmittance distribution T of the active radiation 930 corresponding to the thickness distribution is formed.

  Examples of the material constituting the transparent substrate 9351a include various glass materials such as quartz glass and borosilicate glass, various crystal materials such as crystal and sapphire, polyimide, polyethylene terephthalate, polycarbonate, acrylic resin, and epoxy resin. Such various resin materials are mentioned.

  Examples of the material constituting the shielding film 9351b include metals or metalloids such as aluminum, silicon, titanium, chromium, manganese, iron, nickel, copper, molybdenum, silver, tungsten, and gold, or compounds thereof. (For example, oxide, sulfide, carbide, etc.), carbon such as graphite, and the like.

  Among these, chromium is preferably used from the viewpoints of efficient shielding and excellent durability.

The method for forming the shielding film 9351b is not particularly limited, but various physical film forming methods such as vacuum deposition and sputtering, various chemical film forming methods such as CVD, electrolytic plating, and electroless plating are used. Various plating methods.
Of these, the plating method is preferably used.

  Although the average thickness of the shielding film 9351b is appropriately set depending on the constituent material, it is preferably about 20 to 1000 nm, more preferably about 30 to 300 nm.

FIG. 12 shows another configuration example of the mask shown in FIG.
A mask 935 shown in FIG. 12 has a large number of dot-like shielding films 9351b provided in a dot shape on a transparent substrate 9351a, and the thicknesses of the shielding films 9351b are substantially the same. Except for this, it is the same as the mask 935 shown in FIG.

  By the way, the shielding film 9351b provided in a dot shape is configured such that the intervals are not uniform and are partially different. The distance between the shielding films 9351b is reflected in the shielding rate by the shielding film 9351b when viewed macroscopically, and as a result, is reflected in the transmittance distribution T of the active radiation 930.

  The mask 935 shown in FIG. 12 is configured such that the interval between the shielding films 9351b is wide in the vicinity of the center line C2, and gradually decreases as the distance from the center line C2 increases. Thereby, in the shielding film 9351b, the transmittance distribution T of the actinic radiation 930 corresponding to the distribution of the interval is formed.

  Further, the interval between the shielding films 9351b provided in a dot shape (the distance between the central portions of the adjacent shielding films 9351b) is not particularly limited as long as it is longer than the wavelength of the active radiation 930, but is about 1 to 30 μm. Is preferable, and it is more preferable that it is about 2-20 micrometers. Thereby, the shielding film 9351b provided in a dot shape is less likely to adversely affect the shape of the pattern formed on the layer 910, and the optical waveguide 1 having excellent dimensional accuracy can be formed.

  In order to arrange the shielding film 9351b so that the interval between the dot-like shielding films 9351b continuously changes, the arrangement is determined based on various algorithms, thereby increasing the continuity of the interval. Can do.

  As such an algorithm, for example, an error dispersion method, a systematic dither method, or the like is preferably used.

FIG. 13 shows another configuration example of the mask shown in FIG.
A mask 935 shown in FIG. 13 has a striped shape except that a large number of dot-shaped shielding films 9351b provided in a dot shape are provided in a line with a large number of linear shielding films 9351b. 11 is the same as the mask 935 shown in FIG.

  Here, the linear shielding film 9351b is configured such that the intervals are not uniform and are partially different. The distance between the shielding films 9351b is reflected in the shielding rate by the shielding film 9351b when viewed macroscopically, and as a result, is reflected in the transmittance distribution T of the active radiation 930.

  This is the same as the dot-shaped shielding film 9351b shown in FIG. 12, and the interval between the linear shielding films 9351b (the distance between the central portions of adjacent shielding films 9351b) is actinic radiation. Longer than 930 wavelengths are preferred.

  [3] Next, the cladding layers 11 and 12 are laminated on both surfaces of the core layer 13. Thereby, the optical waveguide 1 is obtained.

  For this, first, the clad layer 11 (12) is formed on the support substrate 952 (see FIG. 9).

  As a method for forming the clad layer 11 (12), a varnish (cladding layer forming composition) containing a clad material is applied and cured (solidified), and a curable monomer composition is applied and cured (solidified). Any method may be used.

  Next, the core layer 13 is peeled from the support substrate 951, and the peeled core layer 13 is sandwiched between the support substrate 952 on which the cladding layer 11 is formed and the support substrate 952 on which the cladding layer 12 is formed (FIG. 10). (See (a)).

10A, pressure is applied from the upper surface side of the support substrate 952 on which the cladding layer 12 is formed, and the cladding layers 11 and 12 and the core layer 13 are pressure bonded.
Thereby, the clad layers 11 and 12 and the core layer 13 are joined and integrated.

  Next, the support substrate 952 is peeled off and removed from the clad layers 11 and 12, respectively (see FIG. 10B). Thereby, the optical waveguide 1 is obtained.

  Thereafter, if necessary, a support film is laminated on the lower surface of the optical waveguide 1, and a cover film is laminated on the upper surface.

  Further, the core layer 13 may be formed directly on the cladding layer 11 instead of on the support substrate 951. Further, the clad layer 12 may be formed by applying a material on the core layer 13 instead of being bonded to the core layer 13.

  Further, in this manufacturing method, the clad layer 11, the core layer 13 and the clad layer 12 are independently formed and then bonded to form the optical waveguide 1, but the composition for forming each layer is used. These layers may be laminated while being collectively formed by a multicolor molding method. In this case, the first layer made of the cladding layer forming composition for forming the cladding layer 11, the second layer made of the core layer forming composition for forming the core layer 13, and the cladding layer A multicolor molded body obtained by laminating a third layer made of the composition for forming a cladding layer for forming 12 is obtained. In addition, when selecting each composition, it is performed so that the refractive index of each layer may satisfy | fill the relationship of (2nd layer)> (1st layer, 3rd layer). Examples of the multicolor molding method include a multicolor extrusion molding method and a multicolor injection molding method.

  Here, the above-described polymer 915 is preferably contained only in the second layer, and the remaining first layer and third layer are preferably comprised of a polymer that does not change the refractive index even when irradiated with actinic radiation. As a result, the refractive index is changed only by the irradiation of the active radiation in the second layer, and the refractive index is not changed by the irradiation of the active radiation in the first layer and the third layer. Thereby, the core part 14 and the side clad part 15 can be formed in the core layer 13, and it can prevent that the refractive index of the clad layers 11 and 12 changes.

  In addition, when performing multicolor molding, it is preferable to mold so that the compositions are partially mixed between the first layer and the second layer and between the second layer and the third layer. . As a result, the refractive index continuously changes between the layers, and finally a graded index type refractive index distribution is formed also in the thickness direction of the optical waveguide 1. That is, by using a multicolor molded body, the optical waveguide 1 having a GI type refractive index distribution not only in the plane direction but also in the thickness direction can be obtained. In such an optical waveguide 1, transmission loss and blunting of the pulse signal can be further suppressed.

  Furthermore, by forming a GI-type refractive index profile in the thickness direction, when a plurality of optical waveguides are stacked, not only crosstalk within the layer but also crosstalk between layers is suppressed. Can do.

(Second manufacturing method)
Next, a second manufacturing method of the optical waveguide 1 (second embodiment of the manufacturing method of the optical waveguide of the present invention) will be described.

  Hereinafter, the second manufacturing method will be described, but the description will focus on differences from the first manufacturing method, and description of similar matters will be omitted.

  The second manufacturing method is the same as the first manufacturing method except that the transmittance distribution T in the opening 9351 of the mask 935 is different. In the following description, an example in which the refractive index of the polymer 915 decreases with irradiation of the active radiation 930 will be described as an example.

  FIG. 14 is a diagram showing the configuration of the mask 935 in the second manufacturing method. FIG. 14A is a plan view of the mask 935, and FIG. 14B is a diagram showing a transmittance distribution for each position of the long side of the opening 9351. When a center line C2 passing through the midpoint of the long side of the opening 9351 and perpendicular to the long side is drawn, the transmittance of the opening 9351 is set to gradually increase as the distance from the vicinity of the center line C2 increases.

The mask 935 is scanned so that the center line C2 of the opening 9351 is along the extending direction of the core portion 14 to be formed. Accordingly, the active radiation 930 that has passed through the opening 9351 is also scanned with respect to the layer 910, and the integrated light amount of the active radiation 930 is minimized on or near the center line R1 of the passage path of the active radiation 930. As a result, the refractive index decreases with distance from the center line R1, and the core portions 14 are formed on both sides of the center line R1.
Similarly, the core portion 14 is also formed near the center line R2 and near the center line R3.

  On the other hand, a side cladding portion 15 is formed in the vicinity of the boundary line B1 located in the middle between the centerline R1 and the centerline R2 and in the vicinity of the boundary line B2 located in the middle between the centerline R2 and the centerline R3.

  As described above, the refractive index distribution W described above is formed in the layer 910. Then, the core layer 13 having the refractive index distribution W is formed (see FIG. 8).

<Electronic equipment>
The optical waveguide of the present invention as described above is excellent in optical transmission efficiency and long-term reliability. For this reason, by providing the optical waveguide of the present invention, a highly reliable electronic device (electronic device of the present invention) capable of performing high-quality optical communication between two points can be obtained.

  Examples of the electronic device including the optical waveguide of the present invention include electronic devices such as a mobile phone, a game machine, a router device, a WDM device, a personal computer, a television, and a home server. In any of these electronic devices, it is necessary to transmit a large amount of data at high speed between an arithmetic device such as an LSI and a storage device such as a RAM. Therefore, by providing such an electronic device with the optical waveguide of the present invention, problems such as noise and signal degradation peculiar to electrical wiring are eliminated, and a dramatic improvement in performance can be expected.

  In addition, the amount of heat generated in the optical waveguide portion is greatly reduced compared to electrical wiring. For this reason, the electric power required for cooling can be reduced and the power consumption of the whole electronic device can be reduced.

  Further, the optical waveguide of the present invention has small transmission loss and pulse signal dullness, and interference does not easily occur even when the number of channels is increased and the density is increased. For this reason, an optical waveguide having high density and a small area and high reliability can be obtained. By mounting the optical waveguide, the reliability of electronic equipment can be improved and the size can be reduced.

  The optical waveguide manufacturing method, the optical waveguide, and the electronic device according to the present invention have been described above. However, the present invention is not limited to this, and for example, any component may be added to the optical waveguide. Good.

Next, examples of the present invention will be described.
1. Optical waveguide manufacturing

Example 1
(1) Synthesis of urethane-urea resin to be photoisomerized First mixed solution was prepared by adding 10 g of 2-methyl-4-nitroaniline, 50 mL of 40% hydrochloric acid and 4 g of sodium nitrite to 120 mL of water. .

  Next, 10 mL of 40% hydrochloric acid and 10 g of m-tolyldiethanolamine were added to 120 mL of water to prepare a second mixed solution.

  And it stirred, adding a 2nd mixed solution slowly in a 1st mixed solution, and prepared the 3rd mixed solution.

  Next, 36 g of potassium hydroxide was added to 200 mL of water, and the obtained aqueous solution was added to 40 g of the prepared third mixed solution. The precipitated product was filtered off. Thereby, an azobenzene group-containing monomer was obtained.

  Next, 2 g of the obtained azobenzene group-containing monomer, 2 g of 4,4′-diphenylmethane diisocyanate, and 0.4 g of trans-2,5-dimethylpiperazine were added to 70 mL of N-methyl-2-pyrrolidone. Thus, a fourth mixed solution was prepared. Then, the fourth mixed solution was heated, and a part of the solvent was slowly volatilized and removed.

  Next, the fourth mixed solution was diluted with 200 mL of pyridine, and the product precipitated by adding ethanol was filtered off. This obtained the polymer (urethane-urea copolymer) which has an azobenzene group in a side chain. The structural formula of the obtained polymer is shown in the following formula (15). However, n in the following formula (15) is 50.

(2) Manufacture of the composition for forming a core layer 10 g of the polymer obtained above was weighed into a 100 mL glass container, and 80 g of pyridine was added thereto and dissolved uniformly, followed by filtration with a 0.2 μm PTFE filter, A clean core layer forming composition was obtained.

(3) Production of optical waveguide (production of lower clad layer)
A polymer having no azobenzene group in the side chain (urethane-urea copolymer) was uniformly applied on a silicon wafer with a doctor blade, and then placed in a dryer at 45 ° C. for 15 minutes. After completely removing the solvent, the entire coated surface was irradiated with 100 mJ of ultraviolet light and heated in a dryer at 120 ° C. for 1 hour to cure the coating film to form a lower clad layer. The formed lower clad layer had a thickness of 20 μm and was colorless and transparent.

(Manufacture of core layer)
The core layer-forming composition was uniformly applied on the lower clad layer with a doctor blade to form a layer, and then placed in a dryer at 45 ° C. for 15 minutes. After the solvent is completely removed, ultraviolet rays (wavelength 405 nm) are applied several times through the mask shown in FIG. 5 (FIG. 11) in a straight line so that the maximum integrated light quantity becomes 1000 mJ / cm ² and while shifting the path. Scanning was performed so as to reciprocate. The layer was then heated in a dryer at 150 ° C. for 1.5 hours. It was confirmed that a very clear waveguide pattern appeared after heating. Moreover, formation of the core part and the side clad part was confirmed. The formed optical waveguide has eight core portions formed in parallel. The shape of the mask opening in plan view was a rectangle having a long side of 120 μm and a short side of 50 μm. When the scanning path is shifted, the interval between the two paths is set to 10 μm. In the obtained optical waveguide, the width of the core portion was 50 μm, the width of the side cladding portion was 80 μm, and the thickness of the core layer was 50 μm.

(Manufacture of upper clad layer)
A dry film of a polymer (urethane-urea copolymer) having no azobenzene group in the side chain is formed on a polyethersulfone (PES) film so as to have a dry thickness of 20 μm. And put into a vacuum laminator set at 140 ° C. for thermocompression bonding. Thereafter, the entire surface was irradiated with ultraviolet rays at 100 mJ and heated in a dryer at 120 ° C. for 1 hour to cure the coating film. Thus, an upper cladding layer was formed and an optical waveguide was obtained.
A length of 10 cm was cut out from the obtained optical waveguide.

(Example 2)
An optical waveguide was obtained in the same manner as in Example 1 except that the mask shown in FIG. 12 was used in the production of the core layer.

(Example 3)
An optical waveguide was obtained in the same manner as in Example 1 except that the mask shown in FIG. 13 was used in the production of the core layer.

Example 4
An optical waveguide was obtained in the same manner as in Example 1 except that the mask shown in FIG. 14 was used in the production of the core layer.

(Example 5)
An optical waveguide was obtained in the same manner as in Example 1 except that a polymer having a structural formula of the following formula (16) (epoxy resin containing an azobenzene group) was used as the polymer to be photoisomerized. However, n of the following formula (16) is 50, and R is a methyl group.

(Example 6)
A polymer (acrylic resin) containing a cinnamoyl group was obtained by reacting an acrylic resin containing a hydroxyl group with cinnamic acid halide in a pyridine solution in the presence of a base. The polymer obtained is photodimerized. And the optical waveguide was obtained like Example 1 by using the obtained polymer as a composition for core layer formation.

(Example 7)
Maleimide acrylate to be photodimerized and triethylamine were added to water to prepare a mixed solution. And the optical waveguide was obtained like Example 1 by using the obtained mixed solution as a composition for core layer formation.

(Example 8)
An optical waveguide was obtained in the same manner as in Example 1 except that a polymer (silicone resin) having a coumarin group in the side chain was used as the core layer forming composition. In addition, the used polymer is what is photodimerized.

Example 9
An optical waveguide was obtained in the same manner as in Example 1 except that a polymer having a main chain composed of a maleimide-norbornene copolymer and a side chain containing an azobenzene group was used as the core layer forming composition. The polymer used is photoisomerized. The maleimide-norbornene copolymer is produced by radically copolymerizing N- (4-hydroxyphenyl) maleimide and 2-norbornene and then reacting this with a compound having an azobenzene group.

(Example 10)
(1) Synthesis of norbornene-based resin to be photodimerized In a glove box where both water and oxygen concentrations are controlled to 1 ppm or less and filled with dry nitrogen, 7.2 g (40.1 mmol) of hexylnorbornene (HxNB), the above 12.9 g (40.1 mmol) of maleimide-based norbornene represented by the formula (11) was weighed into a 500 mL vial, 60 g of dehydrated toluene and 11 g of ethyl acetate were added, and the top was sealed with a silicon sealer.

  Next, 1.56 g (3.2 mmol) of the Ni catalyst represented by the above formula (A) and 10 mL of dehydrated toluene are weighed in a 100 mL vial, put a stirrer chip and sealed, and the catalyst is thoroughly stirred to completely Dissolved in.

  Thereafter, 1 mL of the Ni catalyst solution represented by the above formula (A) was accurately weighed with a syringe, quantitatively injected into a vial bottle in which the two types of norbornene were dissolved, and stirred at room temperature for 1 hour. An increase in viscosity was confirmed. At this point, the stopper was removed, 60 g of tetrahydrofuran (THF) was added, and the mixture was stirred to obtain a reaction solution.

  In a 100 mL beaker, 9.5 g of acetic anhydride, 18 g of hydrogen peroxide (concentration 30%) and 30 g of ion-exchanged water were added and stirred to prepare an aqueous solution of peracetic acid on the spot. Next, the total amount of this aqueous solution was added to the above reaction solution and stirred for 12 hours to reduce Ni.

  Next, the treated reaction solution was transferred to a separatory funnel, the lower aqueous layer was removed, and then 100 mL of a 30% aqueous solution of isopropyl alcohol was added and vigorously stirred. The aqueous layer was removed after standing and completely separating the two layers. After repeating this water washing process three times in total, the oil layer was dropped into a large excess of acetone to reprecipitate the polymer produced, separated from the filtrate by filtration, and then in a vacuum dryer set at 60 ° C. A maleimide-based norbornene polymer was obtained by heating and drying for 12 hours. The molecular weight distribution of the maleimide-based norbornene polymer was Mw = 100,000 and Mn = 40,000 according to GPC measurement. The molar ratio of each structural unit in the maleimide-based norbornene polymer was 50 mol% for the hexylnorbornene structural unit and 50 mol% for the maleimide-based norbornene structural unit, as identified by NMR.

(2) Manufacture of composition for forming core layer 10 g of the purified maleimide-based norbornene polymer was weighed into a 100 mL glass container, and 40 g of mesitylene and 0.01 g of antioxidant Irganox 1076 (manufactured by Ciba Geigy) were added and dissolved uniformly. Then, filtration was performed with a 0.2 μm PTFE filter to obtain a clean composition for forming a core layer.

(3) Production of optical waveguide (production of lower clad layer)
A photosensitive norbornene resin composition (Avatrel 2000P varnish manufactured by Promeras Co., Ltd.) was uniformly applied on a silicon wafer with a doctor blade, and then placed in a dryer at 45 ° C. for 15 minutes. After completely removing the solvent, the entire coated surface was irradiated with 100 mJ of ultraviolet light and heated in a dryer at 120 ° C. for 1 hour to cure the coating film to form a lower clad layer. The formed lower clad layer had a thickness of 20 μm and was colorless and transparent.

(Manufacture of core layer)
The core layer-forming composition was uniformly applied on the lower clad layer with a doctor blade to form a layer, and then placed in a dryer at 45 ° C. for 15 minutes. After the solvent is completely removed, ultraviolet rays (wavelength 405 nm) are applied several times through the mask shown in FIG. 5 (FIG. 11) in a straight line so that the maximum integrated light quantity becomes 1000 mJ / cm ² and while shifting the path. Scanning was performed so as to reciprocate. The layer was then heated in a dryer at 150 ° C. for 1.5 hours. It was confirmed that a very clear waveguide pattern appeared after heating. Moreover, formation of the core part and the side clad part was confirmed. The formed optical waveguide has eight core portions formed in parallel. The shape of the mask opening in plan view was a rectangle having a long side of 120 μm and a short side of 50 μm. When the scanning path is shifted, the interval between the two paths is set to 10 μm. In the obtained optical waveguide, the width of the core portion was 50 μm, the width of the side cladding portion was 80 μm, and the thickness of the core layer was 50 μm.

(Manufacture of upper clad layer)
After a dry film of Avatrel 2000P was previously formed on a polyethersulfone (PES) film so as to have a dry thickness of 20 μm, this dry film was bonded to the core layer and put into a vacuum laminator set at 140 ° C. Then, thermocompression bonding was performed. Thereafter, 100 mJ whole surface was irradiated with ultraviolet rays and heated in a dryer at 120 ° C. for 1 hour to cure Avatrel 2000P. Thus, an upper cladding layer was formed and an optical waveguide was obtained.
A length of 10 cm was cut out from the obtained optical waveguide.

(Example 11)
An optical waveguide was obtained in the same manner as in Example 10 except that the coumarin-based norbornene represented by the above formula (12) was used instead of the maleimide-based norbornene.

(Example 12)
An optical waveguide was obtained in the same manner as in Example 10 except that the cinnamoyl-based norbornene represented by the above formula (13) was used instead of the maleimide-based norbornene.

(Example 13)
An optical waveguide was obtained in the same manner as in Example 10 except that indene-based norbornene represented by the above formula (14) was used instead of maleimide-based norbornene.

(Comparative Example 1)
An optical waveguide was produced in the same manner as in Example 1 except that a polymer having no azobenzene group in the side chain (urethane-urea copolymer) was used as the core layer forming composition. A difference was not formed, and an optical waveguide could not be obtained.

(Comparative Example 2)
An optical waveguide was obtained in the same manner as in Example 1 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 3)
An optical waveguide was obtained in the same manner as in Example 5 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 4)
An optical waveguide was obtained in the same manner as in Example 6 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 5)
An optical waveguide was obtained in the same manner as in Example 7 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 6)
An optical waveguide was obtained in the same manner as in Example 8 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 7)
An optical waveguide was obtained in the same manner as in Example 9 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 8)
An optical waveguide was obtained in the same manner as in Example 10 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 9)
An optical waveguide was obtained in the same manner as in Example 11 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 10)
An optical waveguide was obtained in the same manner as in Example 12 except that a mask having a uniform transmittance distribution was used.

(Comparative Example 11)
An optical waveguide was obtained in the same manner as in Example 13 except that a mask having a uniform transmittance distribution was used.

2. Evaluation 2.1 Refractive Index Distribution of Optical Waveguide With respect to the cross section of the core layer of the optical waveguide obtained in each example, the refractive index distribution was measured by the refractive near field method along the center line in the thickness direction. In addition, since the obtained refractive index distribution has the same refractive index distribution pattern repeated for every core part, a part was cut out from the obtained refractive index distribution, and this was made into the refractive index distribution W. The obtained refractive index distribution W has a shape in which two local maximum values are spaced apart as shown in FIG. 2, and the change in the refractive index is continuous. That is, the refractive index distribution W of the optical waveguide obtained in each example was a GI type distribution.

  Then, from the obtained refractive index distribution W, two maximum values and an average refractive index of the side clad portion were obtained. As a result, the difference between the maximum value of the refractive index distribution W and the average refractive index of the side clad portion was in the range of 1 to 2%.

  On the other hand, regarding the cross section of the core layer of the optical waveguide obtained in each comparative example, the obtained refractive index distribution was an SI type distribution.

2.2 Transmission loss of optical waveguide Light emitted from an 850 nm VCSEL (surface emitting laser) was introduced into an optical waveguide obtained via an optical fiber of 50 μmφ, and received by a 200 μmφ optical fiber to measure the light intensity. . The cutback method was used for the measurement. When the measured values were plotted with the longitudinal direction of the optical waveguide taken on the horizontal axis and the insertion loss on the vertical axis, the measured values were arranged on a straight line. Therefore, the transmission loss was calculated from the slope of the straight line.

  As a result, it was confirmed that the transmission loss was suppressed in the optical waveguides obtained in Examples 1 to 4 as compared with the optical waveguide obtained in Comparative Example 2. Similarly, in the optical waveguides obtained in Examples 5 to 13, it was confirmed that the transmission loss was suppressed as compared with the optical waveguides obtained in Comparative Examples 3 to 11, respectively. In particular, the optical waveguides obtained in Examples 10 to 13 mainly containing norbornene polymer were found to have a particularly small transmission loss as compared with the optical waveguides obtained in other Examples.

2.3 Retention of pulse signal waveform A pulse signal having a pulse width of 1 ns was incident on the obtained optical waveguide from a laser pulse light source, and the pulse width of the emitted light was measured. Then, the degree of bluntness with respect to the pulse width of the incident light was evaluated for the measured pulse width of the emitted light.

  As a result, it was confirmed that in the optical waveguides obtained in Examples 1 to 4, the bluntness of the pulse signal was suppressed as compared with the optical waveguide obtained in Comparative Example 2. Similarly, in the optical waveguides obtained in Examples 5 to 13, it was recognized that the blunting of the pulse signal was suppressed as compared with the optical waveguides obtained in Comparative Examples 3 to 11, respectively. In particular, for the optical waveguides obtained in Examples 10 to 13 mainly composed of norbornene polymer, it became clear that the bluntness of the pulse signal was particularly small as compared with the optical waveguides obtained in other Examples.

2.4 Evaluation of Crosstalk Signal light is incident on one of the eight core portions from an optical fiber having a diameter of 50 μm, and an optical fiber having a diameter of 62.5 μm is disposed on the output side of each core portion. The intensity of the signal light emitted from was measured. Then, the crosstalk was evaluated by comparing the intensity of the emitted light in the core part where the signal light was incident with the intensity of the emitted light in the core part other than the core part.

  As a result, it was confirmed that crosstalk was suppressed in the optical waveguides obtained in Examples 1 to 4 as compared with the optical waveguide obtained in Comparative Example 2. Similarly, in the optical waveguides obtained in Examples 5 to 13, it was recognized that crosstalk was suppressed as compared with the optical waveguides obtained in Comparative Examples 3 to 11, respectively.

  Further, by changing the transmittance distribution of the opening of the mask, a second maximum value that is relatively smaller than these first maximum values between the maximum values (first maximum values) of the GI distribution. It was possible to form a refractive index profile W having

  And the crosstalk was evaluated also about the optical waveguide obtained similarly to each Example except having the refractive index distribution W containing the 1st maximum value and the 2nd maximum value. As a result, in the optical waveguide having the refractive index distribution W including the first maximum value and the second maximum value, the crosstalk is further suppressed as compared with the optical waveguide obtained in each example. Was recognized.

DESCRIPTION OF SYMBOLS 1 Optical waveguide 11, 12 Clad layer 13 Core layer 14 Core part 141, 142 Core part 15 Side surface clad part 151, 152, 153 Side surface clad part 2 Support film 3 Cover film 900 Composition for core layer formation 910 Layer 915 Polymer 920 Addition Agent 930 Actinic radiation 931 1st locus 932 2nd locus 933 3rd locus 935 Mask 9350 Shielding part 9351 Opening 9351a Transparent substrate 9351b Shielding film 951, 952 Support substrate C1, C2 Center line R1, R2, R3 Center line B1 , B2 Boundary line T Transmittance distribution L Integrated light quantity distribution W Refractive index distribution

Claims (9)

At least two clad parts, and a core part provided adjacently between the two clad parts and having a refractive index distribution in which the refractive index continuously decreases from the central part toward the clad parts, A method of manufacturing an optical waveguide having
A first step of forming a layer containing a polymer whose refractive index changes due to isomerization or dimerization of a part of the chemical structure by irradiation with actinic radiation;
Irradiating the layer with actinic radiation through a mask to form the refractive index profile in the layer, and
The method of manufacturing an optical waveguide, wherein the mask includes a transmission portion having a region in which the transmittance of the active radiation is continuously changed.   2. The method of manufacturing an optical waveguide according to claim 1, wherein the mask is set so that the transmittance of the active radiation continuously decreases or increases as the distance from the vicinity of the center line of the transmission portion increases.   The method of manufacturing an optical waveguide according to claim 2, wherein a distribution of transmittance in the transmissive portion is axisymmetric with respect to the center line.   4. The method of manufacturing an optical waveguide according to claim 1, wherein the chemical structure is at least one of an azobenzene group, a maleimide group, a coumarin group, a cinnamoyl group, and an indene group.   5. The method of manufacturing an optical waveguide according to claim 1, wherein the polymer has a main chain and a side chain branched from the main chain and including the chemical structure.   The method for manufacturing an optical waveguide according to claim 1, wherein the polymer is a norbornene-based polymer.   The method of manufacturing an optical waveguide according to claim 1, wherein the active radiation has a peak wavelength in a range of 200 to 450 nm.   An optical waveguide manufactured by the method for manufacturing an optical waveguide according to claim 1.   An electronic apparatus comprising the optical waveguide according to claim 8.