TWI514019B - Optical waveguide and electronic device - Google Patents

Description

Optical waveguides and electronic machines

The present invention relates to optical waveguides and electronic devices.

In recent years, optical communication technology using optical carrier transfer data has become popular as a means for guiding optical carriers from one location to another. The optical waveguide system has a linear core portion and a cladding portion provided to cover the periphery thereof.

As an optical waveguide, the patent document 1 is mentioned, for example. Patent Document 1 describes an optical waveguide in which a refractive index distribution of a core portion is concentrically formed in a cross section by diffusing a refractive index adjusting agent into a polymer matrix. On the other hand, it is described that the refractive index of the coating portion around the core portion is constant. The core portion is composed of a material that is substantially transparent to light of the optical carrier, and the cladding portion is composed of a material having a lower refractive index than the core portion.

Patent Document 1: Japanese Patent Laid-Open No. 2006-276735

In the above technique, when a plurality of core portions are formed, crosstalk may occur between adjacent core portions.

The invention includes the following.

[1] An optical waveguide comprising: a first cladding layer; the core layer is provided on the first cladding layer, and has a cladding portion and a first core portion provided in the in-layer direction, and a cladding portion, a second core portion, and a cladding portion; and a second cladding layer is disposed on the core layer; and the core layer includes a layer of the first core portion and the cladding portion The refractive index distribution W in the direction is continuously changed, and has a region in which the first convex portion, the first concave portion, and the second convex portion are arranged in this order; and the refractive index distribution W located in the first core portion has the first portion a convex portion; the refractive index distribution W located in the coating portion has the second convex portion having a refractive index maximum value smaller than the first convex portion; and the first cladding layer, the coating portion, and the second package The refractive index distribution P in the interlayer direction of the portion of the cladding layer is different between the portion located in the first cladding layer and the portion located in the cladding portion.

[2] The optical waveguide of [1], wherein the refractive index distribution T in the interlayer direction of the portion including the first cladding layer and the first core portion is different from the refractive index distribution W.

[3] The optical waveguide of [1] or [2], wherein a refractive index difference between a maximum refractive index of the first core portion and a maximum refractive index of the first cladding layer is greater than a first core portion The refractive index difference between the maximum value of the refractive index and the maximum refractive index of the coating portion.

[4] The optical waveguide of any one of [1] to [3], comprising: a second core layer provided on the second cladding layer and different from the core layer; the second core The layer system has a third core portion located in the interlayer direction of the first core portion.

[5] The optical waveguide of any one of [1] to [4], wherein a refractive index of a top portion of the first concave portion is smaller than an average refractive index of the coating portion.

[6] The optical waveguide of any one of [1] to [5] wherein the refractive index distribution W is the second convex portion other than the vicinity of the interface between the first core portion and the coating portion. top.

[7] The optical waveguide according to any one of [1] to [6] wherein the refractive index distribution W is provided at a center portion of the covering portion and has a top portion of the second convex portion, and is formed from the second convex portion The top portion of the portion has a region in which the refractive index is continuously reduced toward the first concave portion.

[8] The optical waveguide of any one of [1] to [7] wherein a difference between a refractive index of a top portion of the first concave portion and an average refractive index of the coating portion is a top portion of the first concave portion The difference between the refractive index and the refractive index of the top of the first convex portion is 3 to 80%.

[9] The optical waveguide of any one of [1] to [8], wherein a refractive index difference between a refractive index of a top portion of the first concave portion and a refractive index of a top portion of the first convex portion is 0.005 to 0.07.

[10] The optical waveguide according to any one of [1] to [9] wherein, in the refractive index distribution W, a refractive index of the first convex portion has a value equal to or greater than an average refractive index of the coating portion. When the width of the portion is set to a [μm], and the refractive index of the first concave portion is less than the value of the average refractive index in the coating portion, b [μm], b is 0.01 a to 1.2. a.

[11] An optical waveguide comprising a core portion and a cladding portion adjacent to at least two side surfaces of the core portion, wherein the refractive index distribution of the optical waveguide has a minimum refractive index distribution of at least two minimum values. At least one first maximum value and at least two second maximum values smaller than the first maximum value, and having the second maximum value, the minimum value, the first maximum value, the minimum value, and the second maximum a region in which the values are sequentially arranged; wherein the region including the first maximum value and held by the two minimum values is the core portion, and the region from the minimum value to the second maximum value side is The coating portion; each of the minimum values is less than an average refractive index in the coating portion, and the refractive index changes continuously in the entire refractive index distribution.

[12] An electronic device comprising the optical waveguide of any one of [1] to [11].

According to the present invention, mutual interference between adjacent core portions can be suppressed.

Hereinafter, the optical waveguide and the electronic device of the present invention will be described in detail based on preferred embodiments shown in the drawings.

<Optical Guide>

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

(First embodiment)

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a first embodiment (partially cut and penetrated) of an optical waveguide according to the present invention; and Fig. 2 is a view showing a position of a center line of a core layer in a cross-sectional view taken along line XX of Fig. 1. FIG. 3 is a view showing an example of the intensity distribution of the emitted light when the light is incident on one of the core portions of the optical waveguide shown in FIG. 1 as an example of the refractive index distribution on the horizontal axis and the refractive index as the vertical axis. FIG. In the following description, the upper side in FIG. 1 is referred to as "upper" and the lower side is referred to as "lower". Moreover, Fig. 1 exaggerates the thickness direction of the layers (the upper and lower directions of each figure).

The outline of the optical waveguide in the present embodiment will be described below.

The optical waveguide system of the first embodiment includes a first cladding layer (cladding layer 11), a core layer (core layer 13), and a second cladding layer (cladding layer 12). The core layer (core layer 13) is provided on the cladding layer 11, and has a cladding portion provided in the in-layer direction, a first core portion (core portion 14), a cladding portion (covering portion 15), and The second core portion (core portion 14) and the cladding portion. The second cladding layer is provided on the core layer.

In the core layer, the refractive index distribution W in the in-layer direction of the portion including the first core portion (core portion 14) and the cladding portion (the cladding portion 15) continuously changes, meaning that the first convex portion and the first convex portion are 1 The area in which the concave portion and the second convex portion are arranged in this order. This refractive index distribution is referred to as "W-type refractive index distribution".

The refractive index distribution W located in the first core portion has a first convex portion. The refractive index distribution W located in the cladding portion has a second convex portion having a refractive index maximum value smaller than that of the first convex portion.

The refractive index distribution T in the interlayer direction of the portion including the first cladding layer (cladding layer 11) and the first core portion (core portion 14) may have various refractive index distributions.

Further, the refractive index distribution P in the interlayer direction of the portion including the first cladding layer (cladding layer 11), the cladding portion (the cladding portion 15), and the second cladding layer (cladding layer 12) is at least The portion located in the first cladding layer is different from the portion located in the cladding portion. For example, the refractive index distribution P may vary continuously or may vary discontinuously. The refractive index distribution P is, for example, a refractive index pattern having the same refractive index distribution T. That is, the refractive index distribution P preferably has a fifth convex portion in a region of the cladding portion. Further, it is more preferable that the refractive index distribution P has a sixth convex portion in a region of the first cladding layer. At this time, the refractive index distribution P has a third concave portion between the fifth convex portion and the sixth convex portion. Further, in the refractive index distribution P, the maximum refractive index or the average refractive index in the region of the cladding portion is preferably higher than the value of the maximum refractive index or the average refractive index of the first cladding layer. Further, in the present embodiment, the first cladding layer having the refractive index distribution P, the cladding portion of the core layer, and the second cladding layer have a laminated structure, and the first cladding layer and the core having the refractive index distribution T The laminated structure of the core portion and the second cladding layer of the layer is formed by the same step.

The refractive index distribution P may be the same as the refractive index distribution T (for example, in the refractive index distribution including the cladding portion (cladding) layer adjacent to the core portion, the sixth direction of the vertical and horizontal oblique directions on the plane is the same Except in the case of), it can also be different. In the present embodiment, the refractive index distribution differs in that (i) the refractive index distribution has a different shape; or (ii) the refractive index distribution has the same shape and the refractive index values are different (wherein the manufacturing deviation is visible) For the same). For example, the refractive index difference in the interlayer direction between the adjacent first core portion and the cladding layer may be different from the refractive index difference in the in-layer direction between the adjacent first core portion and the cladding portion.

The refractive index distribution P has, for example, any of "step type (hereinafter referred to as SI type)", "progressive type (hereinafter referred to as GI type)", and W type.

The refractive index distribution T of the SI type means that the refractive index of the core layer and the cladding layer are almost constant, and the refractive index is discontinuous at the boundary between the core layer and the cladding layer. The refractive index distribution P of the GI type means that the refractive index is continuous from the inside of the cladding portion to the first cladding layer. The refractive index distribution change is caused by, for example, a layer moving component that diffuses and moves between layers, and a substance in the stacking direction constitutes a change in continuity.

In the present embodiment, the refractive index distribution P has the following first to third aspects. The first to third aspect patterns correspond to the SI type, the GI type, and the W type, respectively. The first aspect includes a refractive index distribution P in the interlayer direction of the portion of the first cladding layer and the cladding portion, and the interface between the first cladding layer and the cladding portion is discontinuously changed. The second aspect includes a refractive index distribution P in the interlayer direction of the first cladding layer and the portion of the cladding portion, and changes continuously. In the third aspect, the refractive index distribution P in the interlayer direction of the portion including the first cladding layer and the cladding portion is continuously changed, and is arranged in the order of the fifth convex portion, the third concave portion, and the sixth convex portion. In the region, the refractive index distribution P located in the cladding has a fifth convex portion, and the refractive index distribution P located in the first cladding layer has a sixth convex portion having a refractive index maximum value smaller than that of the fifth convex portion.

As described above, in the optical waveguide system of the present embodiment, the refractive index distribution in the in-layer direction of the core layer is W-type, and the refraction of the interlayer direction of the cladding portion is selected by, for example, any of the SI type, the GI type, and the W type. Rate distribution.

Hereinafter, the effects obtained by the optical waveguide of the present embodiment will be described.

The first effect is that higher optical transmission characteristics can be achieved.

In the refractive index distribution in the layer inner direction of the core portion, since the first concave portion is formed at the end portion, the difference in refractive index between the central portion and the end portion of the core portion becomes large. Thereby, mutual interference between the adjacent core portions in the in-layer direction is suppressed. Further, even if light leaks from the core portion, the second convex portion that leaks light in the covering portion can be confined. Thereby, mutual interference between the adjacent core portions in the in-layer direction is suppressed.

The second effect is to obtain a light confinement effect in the interlayer direction of the cladding portion. In the present embodiment, the covering portion includes a coating layer, and the refractive index thereof changes. Therefore, light can be confined in the cladding or cladding.

The optical confinement effect of a layer having a continuous refractive index profile is superior to that of the SI type. As a result, the occurrence of optical transmission loss is effectively suppressed, and high optical transmission characteristics can be realized. Although the reason for this has not been fully explained, it is considered that the light oozing from the core layer is effectively suppressed when the coating portion having the GI-type refractive index distribution is provided.

The third effect is designed to reduce light loss depending on the use of the image.

The first core portion is used as a base point, and the refractive index distribution T in the interlayer direction can be designed to be different from the refractive index distribution W in the in-layer direction. For example, by making the refractive index difference in the interlayer direction larger than the refractive index difference in the in-layer direction, the optical loss when the film of the optical waveguide is bent or wound up in the direction in which the optical waveguide is extended can be reduced. The following is a more detailed description. When the film is bent to a predetermined direction, there is a case where the film is stretched and the refractive index difference is small. On the other hand, by increasing the refractive index difference of the film in the bending direction in advance, the light loss can be reduced even if the refractive index difference is small.

The fourth effect is that the degree of freedom in design is high.

The optical waveguide of the present embodiment is obtained by laminating a thin film, for example. Therefore, the thickness of the coating layer is arbitrarily determined by the relationship with the thickness of the core layer. Moreover, since the thickness can be controlled, the effect of reducing the light coupling loss and the like can be improved.

Hereinafter, the optical waveguide of the present embodiment will be described in detail.

The refractive index distribution of the present embodiment is measured and characterized by a cross section of an optical waveguide which is orthogonal to the direction in which the optical waveguide is extended (for example, the extending direction of the first core portion).

Although three layers are exemplified in the present embodiment, the present invention is not limited to this embodiment, and may have five or more layers. In other words, one or more second core layers may be laminated on the first core layer. Any core layer is preferably held by a cladding layer.

For example, the optical waveguide of the present embodiment is provided on the second cladding layer, and may have a second core layer which is different from the core layer. The second core layer has a third core portion located in the interlayer direction of the first core portion. In other words, the optical waveguide system of the present embodiment includes a plurality of core portions which are separated from each other in the in-layer direction, and may have a plurality of core portions which are separated from each other in the interlayer direction.

For example, in the cross section of the optical waveguide, the core portion of the plural may be arranged in a lattice shape. In the optical waveguide system of this embodiment, for example, a thin film is laminated. Since the center position deviation of the core portion in the interlayer direction is reduced, the light coupling loss is reduced. Further, in the optical waveguide system of the present embodiment, the core portion is formed by, for example, irradiating energy. Since the positional deviation of the core portion in the interlayer direction is reduced, the light coupling loss is reduced.

The refractive index distribution in the inner layer of the core layer may be a W-type portion of at least two adjacent core portions, and the W-type region may be W-shaped on both sides of the core portion, or all of the regions may be W-shaped. . Further, the refractive index distribution of the W-type which is repeated in the direction of the layer may be different for each repeating unit.

The refractive index distribution in the interlayer direction of the core portion may be such that the region of the core portion and the upper cladding layer (or the lower cladding portion) is the refractive index distribution T, and the region on both sides of the core portion may be a refractive index. The distribution T can also repeat the refractive index distribution T in all of its regions. Further, the refractive index distribution T repeated in the interlayer direction may be different for each repeating unit.

The refractive index distribution in the interlayer direction of the cladding portion may be at least different between the first cladding portion and the cladding portion, but may be between the first cladding portion and the cladding portion and the second package. The difference between the cover and the cladding is different. Further, the refractive index distribution P repeated in the interlayer direction may be different for each repeating unit.

The difference in refractive index may be, for example, a difference between the maximum value of the first core portion and the maximum value of the coating portion, or may be the difference between the average value of the first core portion and the average value of the coating portion.

The change in the refractive index distribution continuously means, for example, a transition region in which the refractive index changes slowly, in the vicinity of the interface between the cladding layer and the core layer. A function representing a continuous change in the refractive index in the thickness direction may take various forms, and examples thereof include a spline function, an exponential function, and the like. In the present embodiment, for example, the refractive index between the convex portion and the concave portion changes continuously.

The convex portion (the first convex portion to the sixth convex portion) of the refractive index distribution has either a state having a maximum value at the top portion or a flat portion at the top portion. Further, the concave portion (the first concave portion to the third concave portion) of the refractive index distribution has any of a state in which the top portion has a minimum value or a flat portion at the top portion.

The first core portion may be a region from the maximum value of the first convex portion to the minimum value of the first concave portion, and the covering portion may be a region from the minimum value of the first concave portion to the maximum value of the second concave portion. Further, instead of the maximum value or the minimum value, the center portion of the flat portion at the top may be used.

The width of the flat portion is not particularly limited, and is, for example, preferably 100 μm or less, more preferably 20 μm or less, still more preferably 10 μm or less. By reducing the width of the flat portion, the optical confinement effect becomes high, and the mutual interference between the adjacent core portions can be reduced.

The refractive index distribution of the present embodiment can be obtained by, for example, (1) observing a refractive index-dependent interference fringe using a dual-beam interference microscope, and calculating a refractive index distribution from the interference fringe; or (2) The measurement was performed by a refractive near field method (RNF). The measurement method described in Japanese Laid-Open Patent Publication No. Hei 5-332880 can be used for the refracting near-field method. In the embodiment, since the measurement is simple, a method using an interference microscope is preferred.

An example of a measurement procedure using a refractive index distribution of an interference microscope will be described. First, the optical waveguide is sliced in the cross-sectional direction of the optical waveguide to obtain an optical waveguide fragment. For example, the length of the sliced optical waveguide is 200 μm to 300 μm. Next, a chamber filled with oil having a refractive index of 1.536 was formed in a space surrounded by two glass slides. Here, the optical waveguide segment is inserted into the space in the chamber to prepare a measurement sample, and a blank sample in which the optical waveguide fragment is not inserted is prepared. Next, using a interference microscope, a dry crepe photograph of the cross section of the optical waveguide chip was obtained. The image of the interference pattern is subjected to image analysis to obtain a refractive index distribution. For example, changing the optical path length of the interference microscope continuously obtains image data that changes the appearance of the interference fringes. The refractive index of each measurement point in the interlayer direction and the in-layer direction was calculated from a plurality of image data. The interval between the measurement points is not particularly limited, and is, for example, 2.5 μm.

An example of the optical waveguide of the present embodiment will be described below. In this example, there is a maximum value in the convex portion of the refractive index distribution and a minimum value in the concave portion. Further, for example, the top of the first convex portion is the maximum value Wm2, the top of the second convex portion is the maximum value Wm3, the top of the third convex portion is the maximum value Tm2, and the top of the fourth convex portion is the maximum value Tm3, The top of the concave portion is the minimum value Ws2, and the top of the second concave portion is the minimum value Ts2.

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.

Each part of the optical waveguide 1 will be described in detail below.

The optical waveguide 1 is formed by sequentially laminating the cladding layer 11, the core layer 13, and the cladding layer 12 from the lower side of FIG.

(core layer)

Among them, in the core layer 13, a refractive index distribution is formed in the plane direction. This refractive index distribution has a region where the refractive index is relatively high and a region where the refractive index is relatively high, whereby the incident light can be restricted to a region having a higher refractive index for transmission.

Fig. 2(a) is a cross-sectional view taken along line X-X of Fig. 1, and Fig. 2(b) is a schematic view showing an example of a refractive index distribution on a center line C1 of the center of the thickness direction of the core layer 13 in the X-X line sectional view.

The core layer 13 is in the width direction thereof, and as shown in FIG. 2(b), has a refraction including four minimum values Ws1, Ws2, Ws3, Ws4, and five maximum values Wm1, Wm2, Wm3, Wm4, and Wm5. Rate distribution W. Further, among the five maximum values, there are a maximum value (first maximum value) in which the refractive index is relatively large, and a maximum value (second maximum value) in which the refractive index is relatively small.

Among them, between the minimum value Ws1 and the minimum value Ws2 and between the minimum value Ws3 and the minimum value Ws4, there are maximum values Wm2 and Wm4 having relatively large refractive indices, and other maximum values Wm1, Wm3 and Wm5. The maximum value of the refractive index is relatively small, respectively.

In the optical waveguide 1, as shown in FIG. 2, the core portion 14 is formed between the minimum value Ws1 and the minimum value Ws2 by the maximum value Wm2 having a relatively large refractive index. Similarly, the minimum value Ws3 and the minimum value Ws4 are obtained. The core portion 14 is also included because it contains the maximum value Wm4. Further, in more detail, the core portion 141 is formed between the minimum value Ws1 and the minimum value Ws2, and the core portion 142 is formed between the minimum value Ws3 and the minimum value Ws4.

Further, the left side region of the minimum value Ws1, the minimum value Ws2 and the minimum value Ws3, and the right region of the minimum value Ws4 belong to the region adjacent to both sides of the core portion 14, and thus become the side cladding portion 15. Further, in more detail, the left side region of the minimum value Ws1 is referred to as the side cladding portion 151, and the minimum value Ws2 and the minimum value Ws3 are used as the side cladding portion 152, and the right side region of the minimum value Ws4 is covered as the side surface. Part 153.

In other words, the refractive index distribution W may have at least a region arranged in the order of the second maximum value, the minimum value, the first maximum value, the minimum value, and the second maximum value. Further, this region is repeatedly provided in accordance with the number of core portions. When the core portion 14 is two as in the present embodiment, the refractive index distribution W is such as a second maximum value, a minimum value, a first maximum value, a minimum value, and a second value. The maximum value, the minimum value, the first maximum value, the minimum value, and the second maximum value are arranged such that the maximum value and the minimum value are alternately arranged, and the maximum value is an area in which the first maximum value and the second maximum value are alternately arranged. can.

Further, the minimum value of the complex number, the first maximum value of the complex number, and the second maximum value of the complex number are preferably substantially the same value; if the minimum value is kept smaller than the first maximum value or the second maximum value, the second maximum value If the value is smaller than the first maximum value, the values of each other may be slightly deviated. At this time, the amount of deviation is preferably suppressed within 10% of the average value of the minimum value of the complex number.

Further, the optical waveguide 1 is formed in an elongated strip shape, and the above-described general refractive index distribution W is maintained substantially the same distribution throughout the longitudinal direction of the optical waveguide 1.

With the above refractive index distribution W, two core portions 14 having a long shape and three side cladding portions 15 adjacent to each of the core portions 14 are formed in the core layer 13.

More specifically, on the optical waveguide 1 shown in FIG. 1, two core portions 141 and 142 which are juxtaposed and three side cladding portions 151, 152 and 153 which are juxtaposed are alternately provided. Thereby, each of the core portions 141 and 142 is surrounded by the respective side surface covering portions 151 and 152 153 and the respective cladding layers 11 and 12. Here, since the average refractive index of the two core portions 141 and 142 is higher than the average refractive index of the three side cladding portions 151, 152, and 153, the core portions 141 and 142 and the respective side cladding portions 151 are formed. Total reflection of light can be produced between 152 and 153. Further, the core portions 14 shown in FIG. 1 are marked with a dense point, and the side surface covering portions 15 are indicated with a sparse point.

In the optical waveguide 1, the light incident on one end portion of the core portion 14 is totally reflected between the core portion 14 and the cladding portion (each of the cladding layers 11 and 12 and the side surface cladding portions 15), and is transmitted. To the other side, it can be taken out by the other end of the core portion 14.

Further, in the core portion 14 shown in FIG. 1, the cross-sectional shape is formed into a square or rectangular quadrangular shape (rectangular shape), but the shape thereof is not particularly limited, and may be, for example, a true circle, an annulus circle, or an oblong shape. Polygons such as circles, triangles, pentagons, hexagons, etc.

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

Here, the four minimum values Ws1, Ws2, Ws3, and Ws4 are less than the average refractive index WA of the side cladding portion 15, respectively. Thereby, between the core portion 14 and each of the side surface covering portions 15, there is a region in which the refractive index is smaller than that of the side surface covering portion 15. As a result, a more rapid refractive index slope is formed in the vicinity of each of the minimum values Ws1, Ws2, Ws3, and Ws4. Therefore, light leakage from the core portions 14 is suppressed, and the optical waveguide 1 having a small transmission loss is obtained.

Further, the refractive index distribution W continuously changes in refractive index as a whole. Therefore, the effect of limiting the light to the core portion 14 is further enhanced as compared with the optical waveguide having the step type refractive index distribution, so that the transmission loss is further reduced.

Further, according to the above-described refractive index distribution W having the respective minimum values Ws1, Ws2, Ws3, and Ws4 and having a continuously changing refractive index, it is difficult to collectively transmit the transmitted light in the region closer to the center portion of the core portion 14. A difference occurs in the transmission time per light path. Therefore, even if a pulse signal is included in the transmitted light, the sluggishness of the pulse signal (expansion of the pulse signal) can be suppressed. As a result, the optical waveguide 1 which further improves the optical communication quality can be obtained.

Further, even if the average refractive index difference between the core portion 14 and the side cladding portion 15 is small, the light can be surely limited to the core portion 14.

Further, in the refractive index distribution W, the maximum values Wm2 and Wm4 are located in the core portions 141 and 142 as shown in Fig. 2, but are still located at the center portion of the width in the core portions 141 and 142. As a result, in each of the core portions 141 and 142, the probability that the transmitted light is concentrated at the center portion of the width of the core portions 141 and 142 is increased, and the probability of relatively leaking light to the side surface covering portions 151, 152, and 153 is lowered. As a result, the transmission loss of the core portions 141, 142 can be further reduced.

In addition, for example, the center portion of the width of the core portion 141 is a region that is a distance of 30% of the width of the core portion 141 from both the minimum value Ws1 and the minimum value Ws2.

Further, it is preferable that the positions of the maximum values Wm2 and Wm4 are located at the center of the width of the core portions 141 and 142 as much as possible, but if they are not necessarily the center portion, they are located at the edge portions of the core portions 141 and 142 (with the respective side cladding portions 151, Outside of the vicinity of the 152, 153 contact, there is no significant reduction in characteristics. That is, the transmission loss of the core portions 141, 142 can be suppressed to some extent.

In the vicinity of the edge portion of the core portion 141, for example, a region having a distance of 5% of the width of the core portion 141 from the edge portion toward the inside is referred to.

On the other hand, among the refractive index distributions W, the maximum values Wm1, Wm3, and Wm5 are located in the side surface cladding portions 151, 152, and 153 as shown in Fig. 2(b), and particularly preferably located in the side surface cladding portion 151, The edges of the edges 152 and 153 (portions that are in contact with the core portions 141 and 142) are not. Thereby, since the maximum values Wm2, Wm4 in the core portions 141, 142 and the maximum values Wm1, Wm3, Wm5 among the side cladding portions 151, 152, 153 are sufficiently separated from each other, the transmission in the core portions 141, 142 can be performed. The probability of light leaking into the side cladding portions 151, 152, 153 is sufficiently reduced. As a result, the transmission loss of the core portions 141, 142 can be reduced.

In addition, for example, the vicinity of the edge portion of the side surface covering portions 151, 152, and 153 means a region having a distance of 5% of the width of the side surface covering portions 151, 152, and 153 from the edge portion toward the inside.

Further, the preferred maximum values Wm1, Wm3, and Wm5 are located at the central portion of the width of the side cladding portions 151, 152, and 153, and preferably from the maximum values Wm1, Wm3, and Wm5 toward the adjacent minimum values Ws1, Ws2. Ws3 and Ws4 have a continuous decrease in refractive index. Thereby, the distance between the maximum values Wm2, Wm4 in the core portions 141, 142 and the maximum values Wm1, Wm3, Wm5 among the side cladding portions 151, 152, 153 is ensured to the maximum, and the light can be sure Since it is limited to the vicinity of the maximum values Wm1, Wm3, and Wm5, leakage of the transmitted light from the core portions 141 and 142 can be more reliably suppressed.

Further, although the refractive indices of the maximum values Wm1, Wm3, and Wm5 are smaller than the maximum values Wm2 and Wm4 located at the core portions 141 and 142, and do not have high light transmission properties as the core portions 141 and 142, they are refracted by the core portions 141 and 142. The rate is higher than the surrounding, so it has a little light transmission. As a result, the side cladding portions 151, 152, and 153 limit the transmitted light leaked from the core portions 141 and 142, thereby preventing the waves from reaching the other core portions. That is, mutual interference can be suppressed by the existence of maximum values Wm1, Wm3, and Wm5.

Further, the minimum values Ws1, Ws2, Ws3, and Ws4 are less than the average refractive index WA of the side cladding portion 15 as described above, but the difference is preferably within a predetermined range. Specifically, the difference between the minimum values Ws1, Ws2, Ws3, and Ws4 and the average refractive index WA of the side cladding portion 15 is preferably the minimum value Ws1, Ws2, Ws3, Ws4 and the maximum value Wm2 of the core portions 141, 142. The difference of Wm4 is about 3 to 80%, more preferably about 5 to 50%, and even more preferably about 7 to 20% (for example, (WA-Ws1) / (Wm2-Ws1) × 100, for example, preferably 3 to 80. %, more preferably 5 to 50%, and even more preferably 7 to 20%. (Herein, "~" means that the upper limit and the lower limit are included unless otherwise specified). Thereby, the side cladding portion 15 has sufficient light transmission property for suppressing mutual interference. In addition, by making the difference between the minimum values Ws1, Ws2, Ws3, and Ws4 and the average refractive index WA of the side surface cladding portion 15 equal to or higher than the lower limit value, mutual interference can be sufficiently suppressed. When the value is equal to or less than the above upper limit value, the light transmittance in the side surface covering portion 15 is excessively suppressed, and the light transmittance of the core portions 141 and 142 is lowered.

Further, the difference between the minimum values Ws1, Ws2, Ws3, and Ws4 and the maximum values Wm1, Wm3, and Wm5 is preferably 6 to 90 of the difference between the minimum values Ws1, Ws2, Ws3, and Ws4 and the maximum values Wm2 and Wm4. About %, better 10~70%, and even better 14~40%. Thereby, the balance between the refractive index height of the side cladding portion 15 and the refractive index height of the core portion 14 is optimized, and the optical waveguide 1 has particularly excellent optical transmission properties, and mutual interference can be more reliably suppressed.

Further, the refractive index difference between the minimum values Ws1, Ws2, Ws3, and Ws4 and the maximum values Wm2 and Wm4 of the core portions 141 and 142 is preferably as large as possible, preferably about 0.005 to 0.07, more preferably 0.007. It is about 0.05, more preferably about 0.01 to 0.05 (for example, (Wm1-Ws1) / (Wm2-Ws1) × 100 is preferably 0.005 to 0.07, more preferably 0.007 to 0.05, still more preferably 0.01 to 0.05). By setting the refractive index difference as described above, light can be limited to the core portions 141 and 142.

Further, the refractive index distribution W in the core portions 141 and 142 is such that the cross-sectional position of the core layer 13 is the horizontal axis as shown in Fig. 2(b), and the refractive index is the vertical axis, and the maximum value Wm2 is In the vicinity of the maximum value Wm4, if the refractive index is continuously changed, a convex V-shape may be formed upward (a substantially linear shape other than the maximum value), but it is preferable to form a convex U-shape upward ( The whole circle is rounded around the maximum value). If the refractive index distribution W forms such a shape, the optical confinement effect of the core portions 141, 142 becomes more remarkable.

Further, as shown in FIG. 2(b), the refractive index distribution W is in the vicinity of the minimum value Ws1, the vicinity of the minimum value Ws2, the vicinity of the minimum value Ws3, and the minimum value Ws4. The convex shape is slightly V-shaped (substantially linear except for the maximum value), and it is preferable that the convex shape is slightly U-shaped downward (the entire arc exhibits an arc near the maximum value).

Here, the inventors of the present invention have found that when light is incident on one of the desired end portions of the plurality of core portions 141 and 142 of the optical waveguide 1, and the light intensity distribution of the other end portion is obtained, the intensity distribution is such that the light guide is suppressed. A very useful distribution of the mutual interference of Waves 1.

FIG. 3 is a view showing an intensity distribution of emitted light when light is incident on the core portion 141 of the optical waveguide 1.

When light is incident on the core portion 141, the intensity of the emitted light is maximized at the center of the emission end of the core portion 141. Further, although the light intensity of the emitted light is smaller as it goes away from the center portion of the core portion 141, the light guiding path according to the present invention can obtain a minimum value-like intensity distribution in the core portion 142 adjacent to the core portion 141. In this way, since the minimum value of the intensity distribution of the emitted light is matched by the position of the core portion 142, the mutual interference of the core portion 142 can be suppressed to be extremely small, so that it is possible to surely prevent interference even if multi-channelization and high density are obtained. Optical waveguide 1.

Further, in the conventional optical waveguide, in the core portion adjacent to the core portion into which the light is incident, the intensity distribution of the emitted light does not become a minimum value, but instead becomes a maximum value, so that a mutual interference problem occurs. On the other hand, the behavior of the light intensity distribution in the optical waveguide of the present invention as described above is extremely useful for suppressing mutual interference.

In the optical waveguide of the present invention, although the reason for obtaining such an intensity distribution is unknown, one of the reasons is that the refractive index distribution W has minimum values Ws1, Ws2, Ws3, and Ws4, and the refractive index distribution W The refractive index distribution W, which is characterized by a continuous change in the refractive index of the whole, is such that the light-intensity distribution having a maximum value at the core portion 142 is shifted to the side cladding portion 153 adjacent to the core portion 142. That is, by this shifting, the mutual interference is surely suppressed.

In addition, even if the light-emitting intensity distribution is shifted to the side surface cladding portion 15, since the light-receiving element or the like is disposed in accordance with the position of the core portion 14, the interference is hardly caused, and the optical communication quality is not deteriorated.

Further, although the above-described light emission intensity distribution is high in the optical waveguide of the present invention, it is not necessarily observed, and the NA of the incident light or the cross-sectional area of the core portion 141 is not necessarily observed. The gap between the core portions 141 and 142 and the like may be such that no clear minimum value or a minimum value is deviated from the core portion 142. However, in this case, mutual interference is still sufficiently suppressed.

Further, in the refractive index distribution W shown in FIG. 2(b), when the average refractive index of the side cladding portion 15 is WA, the refractive index in the vicinity of the maximum values Wm2 and Wm4 is continuous and is equal to or higher than the average refractive index WA. The width of the portion is set to a [μm], and the width of the portion in which the refractive index in the vicinity of the minimum values Ws1, Ws2, Ws3, and Ws4 is continuous and is less than the average refractive index WA is set to b [μm]. In this case, b is preferably about 0.01a to 1.2a, more preferably about 0.03a to 1a, still more preferably about 0.1a to 0.8a. Thereby, the substantial widths of the minimum values Ws1, Ws2, Ws3, and Ws4 can exhibit the above-described effects and effects. In other words, by setting b to the lower limit or more, it is possible to suppress the absolute widths of the minimum values Ws1, Ws2, Ws3, and Ws4 from being too narrow, and to reduce the effect of limiting the light to the core portions 141 and 142. On the other hand, when b is equal to or less than the above upper limit value, it is possible to suppress the substantial widths of the minimum values Ws1, Ws2, Ws3, and Ws4 from being excessively wide, and the width or pitch of the core portions 141 and 142 is limited, and the transmission efficiency is lowered. Or multi-channelization and high density is blocked.

Further, the average refractive index WA of the side cladding portion 15 may be, for example, approximately the midpoint of the maximum value Wm1 and the minimum value Ws1.

The constituent material (main material) of the core layer 13 is not particularly limited as long as it is a material having the above refractive index difference, and specifically, an acrylic resin, a methacrylic resin, a polycarbonate, a polystyrene, or the like may be used. Epoxy resin, polyamine, polyimine, polybenzo Oxazole, polydecane, polyazane, polyoxynene resin, fluorine resin or benzocyclobutene resin or Various resin materials such as a cyclic olefin resin such as an olefin resin; a glass material such as quartz glass or borosilicate glass. Further, the resin material may be a composite material in which a different composition is combined, and may also contain an unpolymerized monomer.

In addition, among these, it is especially good for the drop. An olefinic resin. drop The olefin polymer can be, for example, a ring-opening metathesis polymerization (ROMP), a combination of ROMP and a hydrogenation reaction, a polymerization of a radical or a cation, a polymerization using a cationic palladium polymerization initiator, and a polymerization initiation other than the polymerization. It is obtained by a known polymerization method such as polymerization of a reagent (for example, a polymerization initiator of nickel or another transition metal).

(cladding)

The cladding layers 11 and 12 respectively constitute a cladding portion located at the lower portion and the upper portion of the core layer 13.

The average thickness of the cladding layers 11 and 12 is preferably about 0.1 to 1.5 times, more preferably about 0.2 to 1.25 times the average thickness of the core layer 13 (average height of each core portion 14); specifically, the cladding layer 11 The average thickness of 12 is not particularly limited, and is usually preferably about 1 to 200 μm, more preferably about 5 to 100 μm, still more preferably about 10 to 60 μm. Thereby, the optical waveguide 1 is prevented from being enlarged (thickened) to a required level or more, and the function as a covering portion is preferably exhibited.

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

Further, when the constituent material of the core layer 13 and the constituent materials of the cladding layers 11 and 12 are selected, the material may be selected in consideration of the difference in refractive index between the two. Specifically, since the light is surely totally reflected at the boundary between the core portion 14 and the cladding layers 11 and 12, it is only necessary to select a material that sufficiently increases the refractive index of the constituent material of the core portion 14. Thereby, a sufficient refractive index difference is obtained in the thickness direction of the optical waveguide 1, and it is possible to suppress leakage of light from the core portion 14 to the cladding layers 11, 12.

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

Further, the cladding layers 11 and 12 may be provided as needed, or either or both of them may be omitted. At this time, although the surface of the core layer 13 is exposed to the atmosphere (air), since the refractive index of the air is sufficiently low, the air can replace the functions of the cladding layers 11, 12.

(support film)

Below the optical waveguide 1, a support film 2 as shown in FIG. 1 may be laminated as needed.

The support film 2 supports the lower surface of the optical waveguide 1 to protect and reinforce. Thereby, the reliability and mechanical characteristics of the optical waveguide 1 can be improved.

Examples of the constituent material of the support film 2 include various kinds of resin materials such as polyethylene terephthalate (PET), polyethylene, polypropylene-like polyolefin, polyimide, and polyamide. Metal materials such as aluminum and silver. Further, in the case of a metal material, a metal foil is preferably used as the support film 2.

Further, the average thickness of the support film 2 is not particularly limited, but is preferably about 5 to 200 μm, more preferably about 10 to 100 μm. Thereby, since the support film 2 has moderate rigidity, the optical waveguide 1 is surely supported, and it is difficult to hinder the flexibility of the optical waveguide 1.

Further, the support film 2 and the optical waveguide 1 are bonded or bonded together, and as a method thereof, for example, adhesion by heat-pressure bonding, an adhesive or an adhesive may be employed.

Among them, examples of the adhesive layer include an acrylic adhesive, an urethane adhesive, a polyoxynene adhesive, and various other thermal fusion adhesives (polyester, modified olefin). )Wait. Further, as a particularly high heat resistance, it is preferred to use a thermoplastic polymerizable group such as polyimine, polyimine, phthalimide, polyesterimide or polyimine. Imine adhesive. Since the adhesive layer composed of such a material is relatively flexible, even if the shape of the optical waveguide 1 is changed, the change can be freely followed. As a result, peeling accompanying the shape change can be surely prevented.

The average thickness of the adhesive layer is not particularly limited, but is preferably about 1 to 100 μm, more preferably about 5 to 60 μm.

(cover film)

On the other hand, the cover film 3 shown in Fig. 1 may be laminated on the optical waveguide 1 as needed.

The cover film 3 protects the optical waveguide 1 and supports the optical waveguide 1 from above. Thereby, the optical waveguide 1 can be protected from contamination or damage, and the reliability and mechanical characteristics of the optical waveguide 1 can be improved.

The constituent material of the cover film 3 is the same as the constituent material of the support film 2, and examples thereof include polyethylene terephthalate (PET), polyethylene, polypropylene-like polyolefin, and polyimine. Various resin materials such as polyamide, metal materials such as copper, aluminum, and silver. Further, in the case of a metal material, a metal foil is preferably used as the cover film 3. Further, in the case where the mirror is formed on the way of the optical waveguide 1, since the light penetrates the cover film 3, the constituent material of the cover film 3 is preferably substantially transparent.

Further, the average thickness of the cover film 3 is not particularly limited, but is preferably about 3 to 50 μm, more preferably about 5 to 30 μm. When the thickness of the cover film 3 is within the above range, the cover film 3 has a sufficient light transmittance at the time of optical communication, and has sufficient rigidity for surely protecting the optical waveguide 1.

Further, the cover film 3 and the optical waveguide 1 are bonded or bonded to each other, and as a method thereof, for example, adhesion by heat-pressure bonding, an adhesive or an adhesive may be employed. Among them, the above may be used as an adhesive.

In the present embodiment, the optical waveguide 1 composed of the laminate of the cladding layer 11, the core layer 13, and the cladding layer 12 has been described. However, it is also possible to form one of these.

In the present embodiment, the case where the core layer 13 has the two core portions 14 has been described. However, the number of the core portions 14 is not particularly limited, and may be one or three or more.

In the case where the core portion 14 is one, for example, the refractive index distribution W of the transverse cross section of the optical waveguide 1 has two minimum values, and the minimum value is less than the average refractive index WA as described above, and the refractive index distribution W as a whole The medium refractive index may be continuously changed; when the core portion 14 is increased to 3, 4, 5..., the number of the minimum value of the refractive index distribution W is increased to 6, 8, 10... Just one.

<Method of Manufacturing Optical Guide Waves>

Next, an example of a method of manufacturing the optical waveguide 1 will be described.

(first manufacturing method)

First, the first manufacturing method of the optical waveguide 1 will be described.

4 to 8 are views for explaining the first manufacturing method of the optical waveguide 1 shown in Fig. 1, respectively. In the following description, the upper side of FIGS. 4 to 8 is referred to as "upper" and the lower side is referred to as "lower".

The optical waveguide 1 is prepared by preparing the cladding layer 11, the core layer 13, and the cladding layer 12, respectively, and laminating them.

In the first manufacturing method of the optical waveguide 1 [1], the core layer forming composition 900 is applied onto the support substrate 951 to form a liquid film, and then the support substrate 951 is placed on a water platform to planarize the liquid film. And the solvent is evaporated (desolvent). Thereby, the layer 910 is obtained. [2] Next, a refractive index difference is generated by irradiating a portion of the layer 910 with active radiation, thereby obtaining a core layer 13 in which the core portion 14 and the side cladding portion 15 are formed. [3] Next, the cladding layers 11 and 12 are laminated on both surfaces of the core layer 13 to obtain an optical waveguide 1.

Hereinafter, each step will be described in order.

[1] First, a core layer forming composition 900 is prepared.

The core layer forming composition 900 contains a polymer 915 and an additive 920 (in the present embodiment, at least a monomer is contained). The core layer-forming composition 900 is a material which undergoes at least a monomer reaction in the polymer 915 by irradiation with actinic radiation, and thus changes in the refractive index distribution. In other words, the core layer forming composition 900 changes the refractive index distribution due to the variation in the ratio of the presence of the polymer 915 to the monomer. As a result, the core portion 14 and the side cladding portion can be formed in the core layer 13. 15 materials.

Next, the core layer forming composition 900 is applied onto the support substrate 951 to form a liquid film (see FIG. 4( a )). Then, the support substrate 951 is placed on a water platform, the liquid film is planarized, and the solvent is evaporated (desolvent). Thereby, the layer 910 is obtained (refer to FIG. 4(b)).

For the support substrate 951, for example, a tantalum substrate, a ceria 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 dip coating method, a stage coating method, a spray coating method, an applicator method, a curtain coating method, and a die coating method. method.

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

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

(polymer)

The polymer 915 is the base polymer of the core layer 13.

In the polymer 915, it is suitable to use a sufficiently high transparency (colorless and transparent) and to be compatible with a monomer to be described later, and further, a monomer can be reacted (polymerization reaction or crosslinking reaction) as described later. The body still has sufficient transparency after polymerization.

Here, the term "compatibility" means that at least the monomer is mixed, and the core layer forming composition 900 or the layer 910 does not cause phase separation with the polymer 915.

As such a polymer 915, for example, a drop can be mentioned. Cyclic olefin resin such as olefin resin or benzocyclobutene resin, acrylic resin, methacrylic resin, polycarbonate, polystyrene, epoxy resin, polyamine, polyimine Polyphenylene An azole, a polyoxynenoid resin, a fluorine-based resin, etc. can be used, and one type or the combination of two or more types (polymer alloy, polymer dopant (mixture), copolymer, etc.) can be used.

Among these, the most preferred one is a cyclic olefin resin. By using a cyclic olefin resin as the polymer 915, the core layer 13 having superior light transmission performance or heat resistance can be obtained.

The cyclic olefin resin may be unsubstituted or may be substituted with hydrogen.

As a cyclic olefin type resin, for example, it can be mentioned An olefin resin, a benzocyclobutene resin, or the like.

Among them, from the viewpoints of heat resistance, transparency, etc., it is preferred to use An olefinic resin. Again, drop Since the olefinic resin has high hydrophobicity, the core layer 13 which is less likely to cause dimensional change due to water absorption or the like can be obtained.

As a drop The olefinic resin may have a single repeating unit (homopolymer) and have two or more drops. Any one of the olefinic repeat units (copolymers).

As such a drop The olefinic resin may, for example, be:

(1) make a drop The addition of an ethylenic monomer to the (co)polymerization An addition (co)polymer of an olefinic monomer;

(2) drop An addition copolymer of an olefinic monomer with ethylene or an α-olefin;

(3) drop An addition polymer of an olefinic monomer to an addition copolymer of a non-conjugated diene and, if desired, other monomers;

(4) drop a ring-opening (co)polymer of an olefinic monomer, and a resin which hydrogenates the (co)polymer as needed;

(5) drop a ring-opening (co)polymer of an ethylenic monomer with ethylene or an α-olefin, and a resin which hydrogenates the (co)polymer as needed;

(6) drop A ring-opening copolymer of an ethylenic monomer and a non-conjugated diene or other monomer, and a ring-opening polymer such as a resin which hydrogenates the (co)polymer as needed.

As such a polymer, a random copolymer, a block copolymer, an alternating copolymer, etc. are mentioned, for example.

Such a drop The olefinic resin can be polymerized by a ring-opening metathesis polymerization (ROMP), a combination of ROMP and a hydrogenation reaction, a radical or a cation, a polymerization using a cationic palladium polymerization initiator, or a polymerization other than the polymerization. The polymerization of an initiator (for example, a polymerization initiator of nickel or another transition metal) is obtained by all known polymerization methods.

Among these, as a drop The olefinic resin preferably has at least one repeating unit represented by the following structural formula B, that is, an addition (co)polymer. Since the addition (co)polymer is transparent, heat-resistant, and flexible, for example, after the optical waveguide 1 is formed, an electric component or the like is attached via a soldering iron, and even in this case, the optical waveguide can be applied. 1 imparts high heat resistance, that is, resistance to reflow.

[Chemical 1]

Such a drop The olefinic polymer can be reduced, for example, by using the latter An olefinic monomer (decreased by the structural formula C described later) Ethyne monomer or crosslinkability The olefinic monomer is appropriately synthesized.

Further, when the optical waveguide 1 is assembled into various products, there is a case where the product is used, for example, in an environment of about 80 °C. In this case, an addition (co)polymer is preferred from the viewpoint of ensuring heat resistance.

Among them, drop The olefinic resin preferably contains a lowering of a substituent having a polymerizable group. a repeating unit of an ene, or a lowering of a substituent having an aryl group Repeating unit of alkene.

As a substituent having a polymerizable group a repeating unit of an alkene, preferably having a substituent having an epoxy group a repeating unit of an alkene having a substituent having a (meth)acrylic group a repeating unit of an alkene, and a substituent having a substituent containing an alkoxyalkyl group At least one of the repeating units of the alkene. These polymerizable groups are preferred among various polymerizable groups because of their high reactivity.

In addition, if two or more kinds of such a polymerizable group are used, The repeating unit of the olefin can achieve both flexibility and heat resistance.

On the other hand, by containing a substituent having an aryl group-containing substituent The repeating unit of the olefin is more surely prevented from being changed in size due to water absorption due to the extremely high hydrophobicity derived from the aryl group.

Again, drop The olefinic resin preferably contains an alkyl group. Repeat unit of olefin. Further, the alkyl group may be either linear or branched.

By containing an alkyl drop Repeating unit of alkene Since the olefinic resin has high flexibility, it can impart high flexibility.

In addition, it contains an alkyl drop. Drop of repeating unit of alkene The olefinic resin is also preferable because it has excellent transmittance to light in a specific wavelength region (especially, a wavelength region in the vicinity of 850 nm).

As the above contains Drop of repeating unit of alkene Specific examples of the olefinic resin include, for example, hexyl group Homopolymer, phenylethyl drop Homopolymer, benzyl group Homopolymer, hexyl group Alkene and phenylethyl group Copolymer of olefin, hexyl group Alkene and benzyl group a copolymer of an enelate or the like.

Based on this situation, as a drop The olefinic resin is preferably represented by the following formulas (1) to (4) and (8) to (10).

[Chemical 2]

(In the 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.)

Drop of formula (1) The olefinic resin can be produced as follows.

Will have the fall of R ₁ Alkene, and having an epoxy group in the side chain The olefin is dissolved in toluene, and solution polymerization is carried out using the Ni compound (A) as a catalyst to obtain (1).

[Chemical 3]

Still, there is a drop in the epoxy chain in the side chain. The method for producing an alkene is as follows (i) and (ii).

(i) descending Synthesis of olefinic methanol (NB-CH ₂ -OH)

The CPD (cyclopentadiene) produced by the cleavage of DCPD (dicyclopentadiene) is reacted with an alpha olefin (CH ₂ =CH-CH ₂ -OH) under high temperature and high pressure.

[Chemical 4]

(ii) Epoxy drop Synthesis of alkene

By descending It is formed by the reaction of alkene methanol with epichlorohydrin.

[Chemical 5]

Further, in the formula (1), when b is 2 or 3, the methylene group of epichlorohydrin is used as an ethyl group, a propyl group or the like.

Drop shown in equation (1) Alkenyl-based resin, and flexibility can be achieved by the coexistence of the viewpoint of heat resistance, particularly preferably a carbon-based R ₁ is alkyl of 4 to 10, a and b, respectively, of compound 1, for example, drop-butyl Alkene and methyl epoxypropyl ether Copolymer of olefin, hexyl group Alkene and methyl epoxypropyl ether Copolymer of olefin Alkene and methyl epoxypropyl ether a copolymer of an enelate or the like.

[Chemical 6]

(In the 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.)

Drop of formula (2) The olefinic resin can be reduced by having R ₂ Alkenes, and the presence of acrylic and methacrylic groups on the side chains The olefin is dissolved in toluene and obtained by solution polymerization using the above Ni compound (A) as a catalyst.

Still, the drop shown in equation (2) In the olefinic resin, from the viewpoint of flexibility and heat resistance, the particularly preferable R ₂ is a compound having 4 to 10 carbon atoms and c is 1, for example, a butyl group. Alkene and acrylic acid 2-(5-lower Copolymer of alkenyl)methyl ester, hexyl group Alkene and acrylic acid 2-(5-lower Copolymer of alkenyl)methyl ester Alkene and acrylic acid 2-(5-lower A copolymer of an alkenyl)methyl ester or the like.

[Chemistry 7]

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

The resin of formula (3) can be reduced by having R ₄ Alkene, with a drop in the alkyl chain on the side chain The olefin is dissolved in toluene and obtained by solution polymerization using the above-mentioned Ni compound (A) in a catalyst.

Still, the drop shown in equation (3) In the olefin polymer, the particularly preferred compound R ₄ is a compound having 4 to 10 carbon atoms, d is 1 or 2, and X ₃ is a methyl group or an ethyl group, such as a butyl group. Alkene Copolymer of alkenylethyltrimethoxydecane, hexyl group Alkene Copolymer of alkenylethyltrimethoxydecane Alkene Copolymer of alkenylethyltrimethoxydecane, butyl drop Alkene and triethoxynonanyl Copolymer of olefin, hexyl group Alkene and triethoxynonanyl Copolymer of olefin Alkene and triethoxynonanyl Copolymer of olefin, butyl drop Alkene and trimethoxydecyl drop Copolymer of olefin, hexyl group Alkene and trimethoxydecyl drop Copolymer of olefin Alkene and trimethoxydecyl drop a copolymer of an enelate or the like.

[化8]

(In the 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), but are not the same substituent at the same time. Further, p ₄ /q ₄ +r is 20 or less.)

The resin of formula (4) can be reduced by having R ₅ Alkene, and the side chain has a drop of A ₁ and A ₂ The olefin is dissolved in toluene and obtained by solution polymerization using a Ni compound (A) in a catalyst.

[Chemistry 9]

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

[化10]

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

[11]

(In the formula (7), X ₄ each independently represents an alkyl group having 1 to 3 carbon atoms, and h represents an integer of 0 to 3.)

Still, as shown in equation (4) The olefinic resin may, for example, be a butyl group. Alkene Alkene or sulfhydryl group Ethylene, either 2-(5-lower) Alkenyl)methyl ester Alkenylethyltrimethoxydecane and triethoxynonanyl Alkene or trimethoxydecyl drop a tri-copolymer of either of the olefins, a butyl group Alkene Alkene or sulfhydryl group Ethylene or 2-(5-lower) Alkenyl)methyl ester with methyl epoxypropyl ether Triene of olefin, butyl drop Alkene Alkene or sulfhydryl group Ethylene or methyl epoxy propyl ether Alkene Alkenylethyltrimethoxydecane, triethoxynonanyl Alkene or trimethoxydecyl drop a tri-copolymer or the like of any of the alkenes.

[化12]

(In the 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, X ₁ represents an oxygen atom or a methylene group, and X ₂ represents carbon. An atom or a helium atom, i represents an integer from 0 to 3, j represents an integer from 1 to 3, and p ₅ /q ₅ is 20 or less.)

The resin of formula (8) can be reduced by having R ₇ The olefin and the side chain contain -(CH ₂ )-X ₁ -X ₂ (R ₈ ) _3-j (Ar) _j The olefin is dissolved in toluene and obtained by solution polymerization using a Ni compound on a catalyst.

Still, the drop shown in equation (8) In the olefin resin, X ₁ is an oxygen atom, X ₂ is a ruthenium atom, and Ar is a phenyl group.

Further, from the viewpoint of flexibility, heat resistance and refractive index control, particularly preferred R ₇ is an alkyl group having 4 to 10 carbon atoms, X ₁ is an oxygen atom, X ₂ is a halogen atom, and Ar is a phenyl group. a compound wherein R ₈ is a methyl group, i is 1, and j is 2, such as a butyl group. Alkene and diphenylmethyl group Copolymer of olefinic decane, hexyl group Alkene and diphenylmethyl group Copolymer of methoxy methoxy decane Alkene and diphenylmethyl group a copolymer of olefinic decane or the like.

Specifically, it is preferred to use the following An olefinic resin.

[Chemistry 13]

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

Further, from the viewpoint of flexibility, heat resistance and refractive index control, R ₇ in the formula (8) may be an alkyl group having 4 to 10 carbon atoms, X ₁ being a methylene group, and X ₂ being a carbon atom. Ar is a phenyl group, R ₈ is a hydrogen atom, i is 0, and j is 1, such as a butyl group. Alkene and phenylethyl group Copolymer of olefin, hexyl group Alkene and phenylethyl group Copolymer of olefin Alkene and phenylethyl group a copolymer of an enelate or the like.

Again, as a drop As the olefin resin, the following may also be used.

[Chemistry 14]

(In the 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.)

Further, as long as p ₁ /q ₁ to p ₃ /q ₃ , p ₅ /q ₅ , p ₆ /q ₆ or p ₄ /q ₄ +r is 20 or less, it is preferably 15 or less, more preferably 0.1. ~10 or so. In this way, it contains a plurality of species The effect of the repeating unit of the olefin can be effectively exerted.

On the other hand, the polymer 915 can be an acrylic resin, a methacrylic resin, an epoxy resin, a polyimide, a polyoxymethylene resin, a fluorine resin or the like as described above.

In addition, examples of the acrylic resin and the methacrylic resin include poly(methacrylate), poly(methyl methacrylate), poly(epoxy acrylate), and poly(methacrylic acid epoxy). Ester), poly(amino acrylate), 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(methyl) Allyl acrylate), acrylate-epoxy acrylate copolymer (copolymer of methyl methacrylate and glycidyl methacrylate), styrene-epoxy acrylate copolymer, etc.; One or two or more composite materials may be used.

Further, examples of the epoxy resin include an alicyclic epoxy resin, a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, and a biphenyl type having a biphenyl skeleton. Epoxy resin, epoxy resin containing naphthalene ring, dicyclopentadiene type epoxy resin having dicyclopentadiene skeleton, phenol novolak type epoxy resin, cresol novolak type epoxy resin, triphenyl A methane type epoxy resin, a triphenylmethane type epoxy resin, an aliphatic type epoxy resin, and a triepoxypropyl trimeric isocyanate; these may use one or more types of composite materials.

In addition, the polyimine is not particularly limited as long as it is obtained by ring-closing and polyacrylamide of a polyamidene resin precursor which is a precursor of a polyimide resin.

The polyamic acid can be obtained as a solution by reacting a tetracarboxylic dianhydride with a diamine in a molar ratio, for example, in N,N-dimethylacetamide.

Among them, examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 2,2-bis(2,3-dicarboxyl group). Phenyl)-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'-diphenyl ketone tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxybenzene) Base) sulfonic acid dianhydride and the like.

On the other hand, examples of the diamine include m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, and 4,4. '-Diaminodiphenyl hydrazine, 3,3'-diaminodiphenyl hydrazine, 2,2-bis(4-aminophenoxyphenyl)propane, 2,2-bis(4-amine Phenoxyphenyl)hexafluoropropane, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,4-diamine Toluene, 2,6-diaminotoluene, diaminodiphenylmethane, 4,4'-diamino-2,2-dimethylbiphenyl, 2,2-bis(trifluoromethyl)- 4,4'-diaminobiphenyl and the like.

Further, examples of the polyoxymethylene resin include a polyoxymethylene rubber and a polyoxyxene elastomer. These polyoxygenated resins can be obtained by reacting a polyoxyxylene rubber monomer or oligomer with a hardener.

The polyoxyxylene rubber monomer or oligomer may, for example, be a methyl sulfoxyalkyl group, an ethyl sulfoxyalkyl group or a phenyl fluorenyl group.

In addition, as the polyoxyxene rubber monomer or oligomer, since photoreactivity is imparted, it is preferred to use, for example, a functional group such as an epoxy group, a vinyl ether group or an acrylic group.

In addition, examples of the fluorine-based resin include a polymer obtained from a monomer having a fluorine-containing aliphatic ring structure, and a polymer obtained by subjecting a fluorine-containing monomer having two or more polymerizable unsaturated bonds to cyclopolymerization. A polymer obtained by copolymerizing a fluorine-containing monomer and a radical polymerizable monomer.

As the fluorine-containing aliphatic ring structure, for example, perfluoro(2,2-dimethyl-1,3-di) Oxazole), perfluoro(4-methyl-1,3-di Oxazole), perfluoro(4-methoxy-1,3-di Oxazole) and the like.

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

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

Further, since the refractive index of each portion of the core layer 13 is determined by the relationship between the refractive index of the polymer 915 of each portion and the refractive index of the monomer and the ratio of the existence of the monomer, it is also possible to match the type of the monomer used. The refractive index of the polymer 915 is appropriately adjusted.

For example, in order to obtain a polymer 915 having a higher refractive index, a monomer having an aromatic ring (aromatic group), a nitrogen atom, a bromine atom or a chlorine atom in a molecular structure is generally selected to synthesize (polymerize) the polymer 915. . On the other hand, in order to obtain a polymer 915 having a lower refractive index, a monomer having an alkyl group, a fluorine atom or an ether structure (ether group) in a molecular configuration is generally selected, and the polymer 915 is synthesized (polymerized).

As a lower refractive index An olefinic resin, preferably containing an aralkyl group Repeat unit of olefin. Such a drop The olefinic resin has a particularly high refractive index.

As an aralkyl group The aralkyl group (arylalkyl group) of the repeating unit of the alkene may, for example, be a benzyl group, a phenylethyl group, a phenylpropyl group, a phenylbutyl group, a naphthylethyl group, a naphthylpropyl group or a fluorenyl group. Ethyl, decylpropyl and the like; particularly preferably benzyl or phenylethyl. With such a repeating unit The olefinic resin is preferred because it has an extremely high refractive index.

Further, the polymer 915 as described above preferably has a debonding group (debondable side chain) which is branched from the main chain and can be detached from the main chain by at least a part of the molecular structure by irradiation with actinic radiation. Since the refractive index of the polymer 915 is lowered due to the detachment of the debonding group, the polymer 915 can form a refractive index difference by the presence or absence of irradiation with actinic radiation.

The polymer 915 having such a debonding group may, for example, have at least one of a -O- structure, a -Si-aryl structure, and an -O-Si- structure in a molecular structure. Such a debonding group can be more easily detached by the action of a cation.

Among them, the leaving group which lowers the refractive index of the resin by the detachment is preferably at least one of a -Si-diphenyl structure and a -O-Si-diphenyl structure.

Here, as the polymer 915 having a debonding group in the side chain, a polymer of a monocyclic monomer such as cyclohexene or cyclooctene may be mentioned. Alkene Diene, dicyclopentadiene, dihydrodicyclopentadiene, tetracyclododecene, tricyclopentadiene, dihydrotricyclopentadiene, tetracyclopentadiene, dihydrotetracyclopentadiene A cyclic olefin-based resin such as a polymer of a polycyclic monomer. Among these, it is preferred to use one or more kinds of cyclic olefin-based resins selected from the polymers of the polycyclic monomer. Thereby, the heat resistance of the resin can be improved.

Further, as the polymerization form, a known form such as random polymerization or block polymerization can be applied. As for example A specific example of the polymerization of an ethylenic monomer is as follows. (co)polymer of olefinic monomer A copolymer of an ethylenic monomer and another monomer which can be copolymerized, such as an α-olefin, and a hydride of such a copolymer. These cyclic olefin-based resins can be produced by a known polymerization method, such as an addition polymerization method and a ring-opening polymerization method, and among the above, a cyclic olefin resin obtained by an addition polymerization method is preferable (especially Is descending Ethylene resin) (ie, drop Addition polymer of an olefinic compound). Thereby, transparency, heat resistance and flexibility are excellent.

Furthermore, as the side chain has a detachment basis The olefinic resin may, for example, be as shown in the formula (8). In the olefin resin, X ₁ is an oxygen atom, X ₂ is a ruthenium atom, and Ar is a phenyl group.

Further, in the formula (3), a part of the Si-OX ₃ of the alkoxyalkyl group is detached.

In addition, it is speculated, for example, that the drop in the formula (9) is used. In the case of the olefinic resin, the reaction is carried out as follows because of the acid generated by the photoacid generator (hereinafter referred to as PAG). Here, only one part of the detachment base is shown here, and the case where i=1 is also demonstrated.

[化15]

Further, in addition to the structure of the formula (9), those having an epoxy group in the side chain may be used. By using such an object, it is possible to form the core layer 13 which is excellent in adhesion to the coating layers 11, 12 or the substrate.

The following are mentioned as a specific example.

[Chemistry 16]

(In the formula (31), p ₇ /q ₇ +r ₂ is 20 or less.)

a compound represented by the formula (31), which can be reduced, for example, by a hexyl group Alkene and diphenylmethyl group Ethylenoxane (containing -CH ₂ -O-Si(CH ₃ )(Ph) ₂ in the side chain Alkene and epoxy group The olefin is dissolved in toluene and obtained by solution polymerization using a Ni compound on a catalyst.

On the other hand, as another dissociative group, for example, a substituent having an acetophenone structure at the terminal end may be mentioned. This detachable base is more easily detached by the action of free radicals.

The content of the above-mentioned release group is not particularly limited, but is preferably 10 to 80% by weight, particularly preferably 20 to 60% by weight, based on the polymer 915 having a leaving group in the side chain. When the content is within the above range, the flexibility and the refractive index modulation function (the effect of changing the refractive index difference) can be particularly advantageously achieved.

For example, the width of the refractive index change can be expanded by increasing the detachment group content.

(additive)

The additive 920 contains a monomer and a polymerization initiator.

((monomer))

The single system is reacted in the irradiation region of the actinic radiation by the active radiation described later to form a reactant, and the monomer is diffused and moved, whereby the layer 910 can be refracted between the irradiated region and the unirradiated region. The compound with a poor rate.

The reactant of the monomer may, for example, be a polymer formed by polymerizing a monomer in the polymer 915, a crosslinked structure in which the monomers are crosslinked in the polymer 915, and a monomer in the polymer 915. At least one of the branched structures branched by the polymer 915 is polymerized.

However, the difference in refractive index between the irradiated region and the unirradiated region is caused by the difference between the refractive index of the polymer 915 and the refractive index of the monomer, so the single system consideration and polymerization contained in the additive 920 The magnitude relationship between the refractive indices of the objects 915 is selected.

Specifically, in the layer 910, in the case where the refractive index of the irradiation region is preferably high, a polymer 915 having a lower refractive index and a monomer having a higher refractive index relative to the polymer 915 are used in combination. . On the other hand, in the case where the refractive index of the irradiation region is preferably lowered, a polymer 915 having a higher refractive index and a monomer having a lower refractive index relative to the polymer 915 are used in combination.

In addition, the "high" or "low" refractive index does not mean the absolute value of the refractive index, but refers to the relative relationship between a certain material and a certain material.

Further, by the reaction of the monomer (reaction of the reactant), when the refractive index of the irradiation region in the layer 910 is lowered, the portion forms a minimum value of the refractive index distribution W; when the refractive index of the irradiation region rises, the portion constitutes The maximum value of the refractive index distribution.

Further, as the monomer, it is preferred to use a compatibility with the polymer 915 and a difference in refractive index from the polymer 915 of 0.01 or more.

The monomer is not particularly limited as long as it is a polymerizable moiety, and may be, for example, reduced. An olefinic monomer, an acrylic acid (methacrylic acid) monomer, an epoxy monomer, an oxetane monomer, a vinyl ether monomer, a styrene monomer, etc., one of which can be used. Use two or more types in combination.

Among these, as the monomer, a monomer or oligomer having a cyclic ether group such as an oxetanyl group or an epoxy group is preferably used, or An olefinic monomer. By using a monomer or oligomer having a cyclic ether group, since ring opening of a cyclic ether group is likely to occur, a monomer which can react rapidly can be obtained. Again, by using the drop The olefinic monomer can provide the core layer 13 (optical waveguide 1) having excellent light transmission performance and excellent heat resistance and flexibility.

The molecular weight (weight average molecular weight) of the monomer having a cyclic ether group or the molecular weight (weight average molecular weight) of the oligomer is preferably 100 or more and 400 or less, respectively.

The oligomer having an oxetanyl group and an oxetanyl group is preferably selected from the group consisting of the following formulas (11) to (20). By using these, the transparency in the vicinity of the wavelength of 850 nm is excellent, and the flexibility and heat resistance can be achieved. Also, these can be used singly or in combination.

[化17]

[化18]

[Chemistry 19]

[Chemistry 20]

[Chem. 21]

[化22]

[化23]

[Chem. 24]

(In the formula (18), n is 0 or more and 3 or less.)

[化25]

[Chem. 26]

In the above monomers and oligomers, from the viewpoint of ensuring a difference in refractive index with the polymer 915, it is preferred to use (13), (15), (16), (17), (20). ) the compound shown.

Further, in view of the difference in refractive index between the resin of the polymer 915, the small molecular weight, the high mobility of the monomer, and the fact that the monomer is not easily volatilized, it is particularly preferable to use the formula (20) and the formula (15). Compound.

Further, as the compound having an oxetanyl group, a compound represented by the following formula (32) or formula (33) can be used. As the compound represented by the formula (32), a trade name TESOX or the like can be used, and a compound represented by the formula (33) can be used, and a trade name of OX-SQ or the like can be used.

[化27]

[化28]

(In the formula (33), n is 1 or 2.)

Further, examples of the monomer having an epoxy group and the oligomer having an epoxy group include the following. The monomer or oligomer having an epoxy group is polymerized by ring opening in the presence of an acid.

As the monomer having an epoxy group or the oligomer having an epoxy group, those represented by the following formulas (34) to (39) can be used. Among them, from the viewpoint that the strain energy of the epoxy ring is large and the reactivity is excellent, the alicyclic epoxy monomer represented by the formulas (36) to (39) is preferably used.

Further, the compound represented by the formula (34) is an epoxy group. As the compound, for example, EpNB manufactured by Promerus Co., Ltd. can be used. The compound represented by the formula (35) is γ-glycidoxypropyltrimethoxydecane, and as the compound, for example, Z-6040 manufactured by Toray Dow Corning Co., Ltd. can be used. Further, the compound represented by the formula (36) is 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, and as the compound, for example, E0327 manufactured by Tokyo Chemical Industry Co., Ltd. can be used.

Further, the compound represented by the formula (37) is 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate, and as such a compound, for example, Daicel Chemical company CELLOXIDE2021P. Further, the compound represented by the formula (38) is 1,2-epoxy-4-vinylcyclohexane, and as the compound, for example, CELLOXIDE 2000 manufactured by Daicel Chemical Co., Ltd. can be used.

Further, the compound represented by the formula (39) is 1,2:8,9-dihydroxy oxime, and as the compound, for example, CELLOXIDE 3000 manufactured by Daicel Chemical Co., Ltd. can be used.

[化29]

[化30]

[化31]

[化32]

[化33]

[化34]

Further, as the monomer, a monomer having an oxetanyl group, an oligomer having an oxetanyl group, a monomer having an epoxy group, or an oligomer having an epoxy group may be used in combination.

The monomer having an oxetanyl group and the oligomer having an oxetanyl group have a slow initial reaction for starting polymerization and a faster growth reaction. On the other hand, the monomer having an epoxy group and the oligomer having an epoxy group start the polymerization with a faster initial reaction and a slower growth reaction. Therefore, by using a monomer having an oxetanyl group, an oligomer having an oxetanyl group, a monomer having an epoxy group, or an oligomer having an epoxy group, it is possible to illuminate light. A refractive index difference between the light-irradiated portion and the unirradiated portion is generated.

Specifically, when the monomer represented by the formula (20) is used as the "first monomer" and the monomer containing the component B is the "second monomer", it is preferred to use the first monomer and the first monomer. When the monomer is used in a ratio of (the weight of the second monomer) / (the weight of the first monomer), it is preferably about 0.1 to 1, more preferably about 0.1 to 0.6. When the combined ratio is in the above range, the equilibrium between the reactivity speed of the monomer and the heat resistance of the optical waveguide 1 is improved.

Further, the monomer corresponding to the second monomer may, for example, be a monomer having an oxetanyl group or a monomer having a vinyl ether group, which is different from the monomer represented by the formula (20). Among these, at least one of an epoxy compound (particularly an alicyclic epoxy compound) and a bifunctional oxetane compound (a monomer having two oxetanyl groups) is preferably used. By using these second monomers, the reactivity between the first monomer and the polymer 915 can be improved, thereby maintaining transparency and improving the heat resistance of the waveguide.

Specific examples of such a second monomer include a compound of the above formula (15), a compound of the above formula (12), a compound of the above formula (11), a compound of the above formula (18), and the above formula (19). a compound of the above formula (34) to (39).

In addition, the so-called drop The olefinic monomer contains at least one of the following structural formula A The general name of the monomer of the olefin skeleton is, for example, a compound represented by the following structural formula C.

[化35]

[化36]

[wherein, a represents a single bond or a double bond, and R ₁₂ to R ₁₅ each independently represent a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or a functional substituent, and m represents an integer of 0 to 5. However, when a is a double bond, either of R ₁₂ and R ₁₃ and any of R ₁₄ and R ₁₅ do not exist. ]

Examples of the unsubstituted hydrocarbon group (hydrocarvyl group) include a linear or branched carbon number of 1 to 10 (C ₁ to C ₁₀ ), and a linear or branched carbon number of 2 to 10. (C ₂ ~ C ₁₀ alkenyl), linear or branched carbon number 2 to 10 (C ₂ ~ C ₁₀ ) alkynyl group, carbon number 4 to 12 (C ₄ ~ C ₁₂ ) cycloalkyl a cycloalkenyl group having 4 to 12 carbon atoms (C ₄ to C ₁₂ ), an aryl group having 6 to 12 carbon atoms (C ₆ to C ₁₂ ), and an aralkyl group having 7 to 24 carbon atoms (C ₇ to C ₂₄ ) Further, R ₁₂ and R ₁₃ , R ₁₄ and R ₁₅ may each independently be an alkylene group having 1 to 10 carbon atoms (C ₁ to C ₁₀ ).

Further, examples of the monomer other than the above include, for example, acrylic acid, methacrylic acid, acrylate, methacrylic acid ester, decyl acrylate, decyl methacrylate, acrylonitrile, etc., as the acrylic acid (methacrylic acid) monomer. These may be used alone or in combination of two or more.

Specific examples thereof include 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, and 2-butoxyethyl (meth)acrylate.

Further, examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, and isobutyl vinyl. Ether, tert-butyl vinyl ether, n-pentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, n-dodecyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl An alkyl vinyl ether or a cycloalkyl vinyl ether such as a vinyl ether may be used alone or in combination of two or more.

In addition, as the styrene-based monomer, for example, styrene or divinylbenzene may be used, and these may be used alone or in combination of two or more.

Further, the combination of these monomers and the above polymer 915 is not particularly limited, and may be any combination.

Further, the monomer may be at least partially oligomerized as described above.

The amount of such monomers added is preferably 1 part by weight or more and 50 parts by weight or less, more preferably 2 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of the polymer. Thereby, the refractive index between the core and the cladding can be modulated, and the effect of achieving flexibility and heat resistance can be achieved.

((polymerization initiator))

The polymerization initiator is a monomer which acts upon the irradiation of the actinic radiation, and the monomer is reacted, and may be added as needed in consideration of the reactivity of the monomer.

The polymerization initiator to be used is appropriately selected depending on the type of polymerization reaction or crosslinking reaction of the monomer. For example, an acrylic acid (methacrylic acid) monomer or a styrene monomer is preferably a radical polymerization initiator, an epoxy monomer, an oxetane monomer, or a vinyl ether monomer. It is preferred to use a cationic polymerization initiator.

Examples of the radical polymerization initiator include diphenylketones and acetophenones.

On the other hand, examples of the cationic polymerization initiator include those of a Lewis acid-producing type such as a diazonium salt, a strontium salt, and a strontium salt.

In particular, when a monomer having a cyclic ether group is used as a monomer, the following cationic polymerization initiator (photoacid generator) is preferably used.

For example, a sulfonium salt such as triphenylsulfonium trifluoromethanesulfonate or bis(t-butylphenyl)phosphonium-trifluoromethanesulfonate, p-nitrophenyldiazonium hexafluorophosphate or the like is used. Diazo salts, ammonium salts, phosphonium salts, diphenylsulfonium trifluoromethanesulfonate, (triisopropylphenyl)phosphonium-quinone (pentafluorophenyl) borate, etc. Diazomethanes such as diacids, bis(phenylsulfonyl)diazomethane, 1-phenyl-1-(4-methylphenyl)sulfonyloxy-1-benzhydrylmethane, N a sulfonate such as hydroxynaphthylimine-trifluoromethanesulfonate, a diterpenoid such as diphenyldifluorene, or a bis(2,4,6-trichloromethyl)-s-three , 2-(3,4-methylenedioxyphenyl)-4,6-bis(trichloromethyl)-s-three Three Compounds such as the class act as photoacid generators. Further, these photoacid generators may be used singly or in combination of plural kinds.

The content of the polymerization initiator is preferably 0.01 parts by weight or more and 0.3 parts by weight or less, more preferably 0.02 parts by weight or more and 0.2 parts by weight or less based on 100 parts by weight of the polymer. Thereby, there is an effect of improving reactivity.

Further, in the case where the reactivity of the monomer is remarkably high, the addition of the polymerization initiator may be omitted.

Among them, the sensitizer increases the sensitivity of the polymerization initiator to light, has a function of reducing the time or energy required for activation (reaction or decomposition) of the polymerization initiator, or changes the wavelength of light to be suitable for polymerization. The function of the wavelength at which the initiator is activated.

The sensitizer is appropriately selected depending on the sensitivity of the polymerization initiator or the peak wavelength of the absorption of the sensitizer, and is not particularly limited, and examples thereof include 9,10-dibutoxy fluorene (CAS No. 76275). -14-4) Classes, cockroaches, phenanthrenes, Class, benzopyrene, Fluorhenens, erythroprene, anthraquinone, indanthrene, thioxanthen-9-ones, etc., which may be used singly or as a mixture.

Specific examples of the sensitizer include 2-isopropyl-9H-thioxanthene-9-one, 4-isopropyl-9H-thioxanthene-9-one, and 1-chloro-4-propoxy group. Thioxanthone, thiophene (phenothiazine) or a mixture of these.

The content of the sensitizer is preferably 0.01% by weight or more, more preferably 0.5% by weight or more, still more preferably 1% by weight or more, based on the core layer forming composition 900. Further, the upper limit is preferably 5% by weight or less.

Further, the additive 920 may further contain a catalyst precursor, a catalyst, an antioxidant, an ultraviolet absorber, a photo-stabilizer, a decane coupling agent, a coating surface modifier, a thermal polymerization inhibitor, a leveling agent, a surfactant, A coloring agent, a storage stabilizer, a plasticizer, a slip agent, a filler, inorganic particles, an anti-aging agent, a wettability improver, an antistatic agent, and the like.

The layer 910 comprising the above polymer 915 and additive 920 has a predetermined refractive index due to the action of the uniformly dispersed additive 920 in the polymer 915.

[2] Next, a masking 935 having an opening (window) 9351 is prepared, and the layer 910 is irradiated with the active radiation 930 (see FIG. 5) via the mask 935.

Hereinafter, a case where a member having a refractive index lower than that of the polymer 915 is used as a monomer will be described as an example.

That is, in the example shown here, the irradiation region 925 of the actinic radiation 930 mainly becomes the side cladding portion 15.

In the example shown here, the pattern of the side cladding portion 15 to be formed and the equivalent opening (window) 9351 are mainly formed on the mask 935. This opening 9351 forms a penetration portion through which the irradiated active radiation 930 penetrates. Further, since the pattern of the core portion 14 or the side cladding portion 15 is determined by the refractive index distribution W formed by the irradiation of the active radiation 930, the pattern of the opening 9351 and the pattern of the side cladding portion 15 are not completely identical. A slight deviation sometimes occurs between the above two patterns.

The mask 935 may be formed in advance (otherwise formed) (for example, a flat plate), or may be formed on the layer 910 by, for example, a vapor phase film formation method or a coating method.

Examples of preferred examples of the mask 935 include a light mask made of quartz glass or a PET substrate, a template mask, a vapor phase film formation method (evaporation, sputtering, etc.). Among metal films and the like, among them, it is particularly preferable to use a light mask or a template mask. Since it can form a fine pattern with high precision, it is easy to operate at the same time, which is advantageous for improving productivity.

In addition, in FIG. 5, the opening (window) 9351 of the mask 935 is partially removed from the mask along the pattern of the irradiation region 925 of the active radiation 930, but it is made of the above quartz glass or PET substrate. In the case of the light mask, a shield portion of the actinic radiation 930 formed of a masking material made of a metal such as chromium may be used for the light mask. In this mask, a portion other than the shielding portion becomes the above-described window (penetrating portion).

The active radiation 930 to be used may be any one that can cause a photochemical reaction (change) to the polymerization initiator and a detachable group contained in the polymer 915. For example, visible light, ultraviolet light, or the like can be used. Infrared light, laser light, electron beam or X-ray.

In the above, the active radiation 930 is appropriately selected depending on the type of the polymerization initiator or the detachment group, and the type of the sensitizer when the sensitizer is contained, and is not particularly limited, and is preferably at a wavelength of 200. Those with a peak wavelength in the range of ~450 nm. Thereby, it is easier to activate the polymerization initiator, and the release group is more easily detached.

Further, the irradiation amount of the active radiation 930 is preferably about 0.1 to 9 J/cm ² , more preferably about 0.2 to 6 J/cm ² , still more preferably about 0.2 to 3 J/cm ² .

When the layer 910 is irradiated with the actinic radiation 930 via the mask 935, the polymerization initiator is activated in the irradiation region 925. Thereby, the monomer is polymerized in the irradiation region 925. If the monomer is polymerized, since the amount of the monomer in the irradiation region 925 is reduced, the monomer in the unirradiated region 940 is thus diffused and moved into the irradiation region 925. As described above, the polymer 915 and the single system are appropriately selected in such a manner that a refractive index difference occurs between them, so that a refractive index difference occurs between the irradiation region 925 and the non-irradiated region 940 as the monomer diffuses and moves.

FIG. 9 is a view for explaining a case where a refractive index difference is generated between the irradiation region 925 and the non-irradiation region 940, and shows a case where the position of the cross section of the layer 910 is the horizontal axis and the refractive index of the cross section is the vertical axis. A map of the refractive index profile.

In the present embodiment, since the refractive index is smaller than that of the polymer 915, the refractive index of the unirradiated region 940 becomes higher as the monomer diffuses and moves, and the refractive index of the irradiated region 925 becomes lower (refer to the figure). 9(a)).

The diffusion movement of the monomer is considered to be caused by the fact that the monomer is consumed in the irradiation region 925, and thus the concentration gradient of the formed monomer is caused. Therefore, the monomers of the entire unirradiated region 940 do not gradually face toward the irradiation region 925, but gradually start moving from the portion close to the irradiation region 925, and the monomer also starts to be from the central portion of the unirradiated region 940 in order to make up. Move outside. As a result, as shown in FIG. 9(a), the high refractive index portion H is formed on the side of the non-irradiated region 940, and the low refractive index portion L is formed on the side of the irradiation region 925, at the boundary between the rubbing irradiation region 925 and the non-irradiated region 940. Since the high refractive index portion H and the low refractive index portion L are formed by the diffusion movement of the above-described respective monomers, they are necessarily formed by a smooth curve. Specifically, the high refractive index portion H is, for example, slightly convex in a U shape, and the low refractive index portion L is formed in a slightly U shape, for example, downward.

Further, the refractive index of the polymer obtained by polymerizing the above monomer is almost the same as the refractive index of the monomer before polymerization (the refractive index difference is about 0 to 0.001), so that in the irradiation region 925, with the monomer The polymerization is carried out, and the refractive index is lowered by the amount of the monomer and the amount of the substance derived from the monomer. Therefore, the shape of the refractive index distribution W can be controlled by appropriately adjusting the amount of the monomer relative to the polymer.

On the other hand, in the unirradiated region 940, since the polymerization initiator is not activated, the monomer is not polymerized.

Further, in the irradiation region 925, as the polymerization of the monomer proceeds, the ease of diffusion of the monomer gradually decreases. Therefore, in the irradiation region 925, the closer to the unirradiated region 940, the higher the monomer concentration itself, and the larger the refractive index reduction amount becomes. As a result, the distribution shape of the low refractive index portion L formed in the irradiation region 925 is likely to be asymmetric to the left and right, and the gradient on the side of the non-irradiation region 940 is more urgent. Therefore, the refractive index distribution W of the optical waveguide of the present invention is formed.

Further, the polymer 915 preferably has a detachment group as described above. This detachable base is detached by irradiation with the active radiation 930, and the refractive index of the polymer 915 is lowered. Therefore, when the active radiation 930 is irradiated to the irradiation region 925, the diffusion movement of the monomer starts, and the release group is detached from the polymer 915, and the refractive index of the irradiation region 925 becomes lower than before the irradiation (refer to FIG. 9(b)). ).

Since the decrease in the refractive index occurs uniformly in the entire irradiation region 925, the refractive index difference between the high refractive index portion H and the low refractive index portion L is further increased. As a result, the refractive index distribution W shown in Fig. 9(b) was obtained. Further, the change in the refractive index of Fig. 9(a) occurs almost simultaneously with the change in the refractive index of Fig. 9(b). This refractive index difference is further enlarged by such a refractive index change.

In the present embodiment, the refractive index distribution of the core layer after the energy irradiation can be controlled by appropriately adjusting the constituent components of the core layer before the energy irradiation, the irradiation amount of the energy irradiation, or the dryness of the core layer before the energy irradiation. shape.

Further, by adjusting the amount of irradiation of the active radiation 930, the formed refractive index difference and the shape of the refractive index distribution can be controlled. For example, by increasing the amount of irradiation, the refractive index difference can be increased. Further, by adjusting the content of the photoacid generator and the irradiation amount, the shape of the refractive index distribution can be controlled. Further, the layer 910 may be dried before the irradiation of the active radiation 930, and the shape of the refractive index distribution may be controlled by adjusting the degree of drying at this time. For example, by increasing the degree of drying, the diffusion movement of the monomer can be suppressed. Further, by increasing the drying temperature, the amount of diffusion can be increased to control the refractive index distribution.

Next, the layer 910 is subjected to a heat treatment. In this heat treatment, the monomer in the irradiated light irradiation region 925 is further polymerized. On the other hand, in this heating step, the monomer in the unirradiated region 940 is volatilized. Thereby, the amount of the monomer in the unirradiated region 940 is further reduced, and the refractive index is increased to become close to the refractive index of the polymer 915.

The heating temperature in the heat treatment is not particularly limited, but is preferably about 30 to 180 ° C, more preferably about 40 to 160 ° C.

Further, the heating time is preferably set such that the polymerization reaction of the monomer in the irradiation region 925 is almost completed, and specifically, it is preferably about 0.1 to 2 hours, more preferably about 0.1 to 1 hour.

Further, this heat treatment may be performed as needed or may be omitted.

According to the above principle, the core layer 13 having the refractive index distribution W can be obtained (refer to FIG. 6).

In the refractive index distribution W, there are minimum values Ws1, Ws2, Ws3, and Ws4 (see FIG. 2(b)) in which the low refractive index portion L is converted, and the positions of these minimum values correspond to the core portion 14 and the side cladding portion 15 The boundary between the two.

Further, the refractive index distribution W has a certain correlation with the concentration of the structural body derived from the monomer in the core layer 13. Therefore, by measuring the concentration of the structure derived from the monomer, the refractive index distribution W of the optical waveguide 1 can be indirectly characterized.

The measurement of the concentration of the construct can be carried out using, for example, FT-IR, TOF-SIMS line analysis, surface analysis, or the like.

Further, by having a certain correlation between the intensity distribution of the light emitted from the optical waveguide 1 and the refractive index distribution W, the refractive index distribution W can be indirectly characterized.

Of course, the refractive index distribution W can also be directly characterized by a refractive near-field method, a differential interference method, or the like.

Further, when a monomer having a refractive index higher than that of the polymer 915 is used as a monomer, contrary to the above, since the refractive index of the moving destination becomes high accompanying the diffusion movement of the monomer, the irradiation region can be set in accordance with this case. 925 and unirradiated area 940.

Further, when light having high directivity such as laser light is used as the active radiation 930, the use of the mask 935 can be omitted.

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

First, a cladding layer 11 (12) is formed on the support substrate 952 (refer to FIG. 7).

As a method of forming the coating layer 11 (12), a method of applying a varnish (a composition for forming a coating layer) containing a coating material and curing (curing), and applying a monomer having curability can be applied. Any method such as a method of hardening (curing) the object.

Next, the core layer 13 is peeled off from the support substrate 951 to form the support substrate 952 on which the cladding layer 11 is formed, and the core layer 13 is held by the support substrate 952 on which the cladding layer 12 is formed (see FIG. 8(a)).

Then, as shown by the arrow in FIG. 8(a), the upper surface side of the support substrate 952 on which the cladding layer 12 is formed is pressed, and the cladding layers 11, 12 and the core layer 13 are pressure-bonded.

Thereby, the cladding layers 11 and 12 and the core layer 13 are joined and integrated (see FIG. 8(b)).

Next, the support substrate 952 is peeled off and removed by the cladding layers 11 and 12, respectively. Thereby, the optical waveguide 1 is obtained.

Thereafter, the film 2 is supported by the area under the optical waveguide 1 as needed, and the film 3 is covered by the upper layer.

Further, the core layer 13 may not be formed on the support substrate 951 and formed on the cladding layer 11. Further, the cladding layer 12 may be formed by coating the material on the core layer 13 without adhering to the core layer 13.

(Second manufacturing method)

Next, a second manufacturing method of the optical waveguide 1 will be described.

In the following, the second manufacturing method will be described, but the description will be focused on the differences from the first manufacturing method described above, and the description of the same matters will be omitted.

In the second manufacturing method, the composition of the core layer forming composition 900 is the same as that of the first manufacturing method except that the composition of the core layer forming composition 900 is different.

In the second manufacturing method of the optical waveguide 1, the liquid film is formed by coating the core layer forming composition 900 on the support substrate 951, and then the supporting substrate 951 is placed on a water platform to planarize the liquid film. At the same time, the solvent is evaporated (desolvent). Thereby a layer 910 is obtained. [2] Next, after irradiating one portion of the layer 910 with active radiation, the layer 910 is subjected to heat treatment to produce a refractive index difference, and the core layer 13 in which the core portion 14 and the side cladding portion 15 are formed is obtained. [3] Next, the cladding layers 11 and 12 are laminated on both surfaces of the core layer 13 to obtain an optical waveguide 1.

Hereinafter, each step will be described in order.

[1] First, a core layer forming composition 900 is prepared.

The core layer-forming composition 900 used in the second production method contains a catalyst precursor and a promoter, in place of the polymerization initiator.

The catalyst precursor is a substance which can initiate a monomer reaction (polymerization reaction, crosslinking reaction, etc.), and which changes the activation temperature by the action of a promoter activated by light irradiation. By the change in the activation temperature, a temperature difference between the light irradiation region 925 and the non-irradiation region 940 causes the monomer reaction to start, and as a result, the monomer can be reacted only in the irradiation region 925.

As a catalyst precursor, any compound may be used as long as the activation temperature changes (rises or falls) with the irradiation of the active radiation, and it is particularly preferable that the activation temperature is lowered by irradiation with active radiation. Thereby, the core layer 13 (the optical waveguide 1) can be formed in the heat treatment at a lower temperature, and unnecessary heat can be prevented from being applied to the other layers to lower the characteristics (light transmission performance) of the optical waveguide 1.

As such a catalyst precursor, a substance mainly containing at least one of the compounds represented by the following formulas (Ia) and (Ib) is suitably used.

[化37]

(E(R) ₃ ) ₂ Pd(Q) ₂ ...(Ia)

[(E(R) ₃ ) _a Pd(Q)(LB) _b ] _p [WCA] _r ...(Ib)

[In each of Formulas Ia and Ib, E(R) ₃ represents a Group 15 neutral electron donor ligand, E represents an element selected from Group 15 of the periodic table, and R represents a hydrogen atom (or an isotope thereof) One) or a hydrocarbon group, and Q represents an anionic ligand selected from the group consisting of a carboxylate, a sulfuric acid ester, and a dithiocarboxylic acid ester. Further, in the formula Ib, LB represents a Lewis base, WCA represents a weakly coordinating anion, a represents an integer of 1 to 3, b represents an integer of 0 to 2, and a total of a and b is 1 to 3, and p and r represent palladium. The number of charge equalizations of cations and weakly coordinating anions. ]

Typical catalyst precursors of the formula Ia include, for example, Pd(OAc) ₂ (P(i-Pr) ₃ ) ₂ , Pd(OAc) ₂ (P(Cy) ₃ ) ₂ Pd(O ₂ CCMe ₃ ). ₂ (P(Cy) ₃ ) ₂ , Pd(OAc) ₂ (P(Cp) ₃ ) ₂ Pd(O ₂ CCF ₃ ) ₂ (P(Cy) ₃ ) ₂ , Pd(O ₂ CC ₆ H ₅ ) ₃ (P(Cy) ₃ ) ₂ , but is not limited to this. Here, Cp represents a cyclopentyl group, and Cy represents a cyclohexyl group.

Further, as the catalyst precursor represented by Formula Ib, it is preferred that each of p and r is a compound selected from an integer of 1 and 2.

As a typical catalyst precursor of the above formula Ib, for example, Pd(OAc) ₂ (P(Cy) ₃ ) ₂ can be mentioned. Here, Cy represents a cyclohexyl group, and Ac represents an ethyl fluorenyl group.

These catalyst precursors allow the monomer to react efficiently (in descending In the case of an ethylenic monomer, a polymerization reaction or a crosslinking reaction is carried out efficiently by an addition polymerization reaction.

In addition, in the state where the activation temperature is lowered (active potential state), as the catalyst precursor, the activation temperature is preferably about 10 to 80 ° C lower than the original activation temperature (preferably about 10 to 50 ° C). ). Thereby, the refractive index difference between the core layer 14 and the side cladding portion 15 can be surely generated.

As such a catalyst precursor, it is more suitable to contain (mainly) at least one of Pd(OAc) ₂ (P(i-Pr) ₃ ) ₂ and Pd(OAc) ₂ (P(Cy) ₃ ) ₂ . Substance.

The cocatalyst is activated by irradiation with active radiation, and the activation temperature of the catalyst precursor (the temperature at which the monomer reacts) can be changed.

As the cocatalyst, any compound which is activated by irradiation with active radiation and whose molecular structure is changed (reacted or decomposed) can be used, and it is suitable to use (mainly) the following compound (light) Starting agent: A compound which decomposes by irradiation with active radiation of a specific wavelength to generate a cation such as a proton or another cation, and a weakly coordinating anion (WCA) which can be substituted with a debonding group of a catalyst precursor.

Examples of the weakly coordinating anion include cerium (pentafluorophenyl) borate ion (FABA ^- ), hexafluoroantimonic acid ion (SbF ₆ ^- ), and the like.

As the cocatalyst (photoacid generator or photobase generator), iridium (pentafluorophenyl) borate or hexafluoroantimonate or ruthenium (pentafluorophenyl) cadmate represented by the following formula can be exemplified. , aluminates, silicates, other borates, cadmiums, carboranes, halocarbboranes, etc.

[化38]

As a commercial product of such a catalyst, for example, "RHODORSIL (registered trademark, the same as below) PHOTOINITIATOR 2074 (CAS No. 178233-72-2)" available from Rhodia USA Co., Cranbury, NJ. "TAG-372R ((dimethyl(2-(2-naphthyl)-2-yloxyethyl) fluorene (pentafluorophenyl) borate) available from Toyo Ink Manufacturing Co., Ltd., Tokyo, Japan : CAS No. 193957-54-9)); "MPI-103 (CAS No. 87709-41-9)" available from Midori Chemical Co., Ltd., Tokyo, Japan; may be manufactured by Tokyo Toyo Ink Co., Ltd. "TAG-371 (CAS No. 193957-53-8)" obtained by the company; "TTBPS-TPFPB (referenced to 4-tert-butylphenyl)" available from Toyo Seiki Co., Ltd., Tokyo, Japan (Pentafluorophenyl)borate); "NAI-105 (CAS No. 85432-62-7)" obtained from Midori Chemical Industry Co., Ltd., Tokyo, Japan.

In addition, when RHODORSIL PHOTOINITIATOR 2074 is used as the auxiliary catalyst, ultraviolet rays (UV light) are preferably used as the active radiation (chemical rays) to be described later, and a mercury lamp (high pressure mercury lamp) is suitably used as the ultraviolet irradiation means. Thereby, the layer 910 can be supplied with ultraviolet rays (active radiation) having a sufficient energy of less than 300 nm, and the RHODORSIL PHOTOINITIATOR 2074 can be efficiently decomposed to generate the above cations and WCA.

[2]

[2-1] Next, in the same manner as in the first manufacturing method, the layer 910 is irradiated with the active radiation 930 via the mask 935.

In the irradiation region 925, the promoter reacts (bonds) or decomposes by the action of the active radiation 930 to liberate (produce) a cation (proton or other cation) from a weakly coordinating anion (WCA).

Then, the cation or weakly coordinating anion changes (decomposes) the molecular structure of the catalyst precursor present in the irradiation region 925, and changes it to an active latent state (latent active state).

Here, the catalyst precursor of the active latent state (or latent active state) means that the activation temperature is lowered below the original activation temperature, and if there is no temperature rise, that is, at room temperature, it is impossible to A catalyst precursor in a state in which the monomer reaction occurs in the irradiation region 925.

Therefore, even after the irradiation of the actinic radiation 930, if the layer 910 is stored at about -40 ° C, for example, the monomer reaction can be maintained without maintaining the state. Therefore, the layer 910 after the irradiation of the plurality of active radiation 930 is prepared, and the heat treatment described later is performed once, whereby the optical waveguide 1 (for example, the core layer 13) can be obtained, and the convenience is high.

Further, in the same manner as in the first production method, the release group is separated from the polymer 915, except that the molecular structure of the catalyst precursor is changed. Thereby, a refractive index difference is generated between the irradiation region 925 of the layer 910 and the non-irradiated region 940.

[2-2] Next, the layer 910 is subjected to heat treatment (first heat treatment). Thereby, in the irradiation region 925, the catalyst precursor in the active latent state is activated (in an active state), and a monomer reaction (polymerization reaction or crosslinking reaction) occurs.

Then, when the monomer reaction proceeds, the monomer concentration in the irradiation region 925 gradually decreases. Therefore, a difference in monomer concentration occurs between the irradiation region 925 and the unexposed region 940. To eliminate this, the monomer is diffused and moved from the unirradiated region 940 to the irradiation region 925.

As a result, the same refractive index distribution as in the first manufacturing method is formed in the layer 910.

The heating temperature of the heat treatment is not particularly limited, but is preferably about 30 to 80 ° C, more preferably about 40 to 60 ° C.

Further, it is preferable that the heating time is set such that the monomer reaction in the irradiation region 925 is almost completed, and specifically, it is preferably about 0.1 to 2 hours, more preferably about 0.1 to 1 hour.

Next, the second heat treatment is performed on the layer 910.

Thereby, the catalyst precursor remaining in the unirradiated region 940 and/or the irradiation region 925 is activated (activated state) directly or in conjunction with the activation of the promoter, thereby remaining in each region 925. , 940 monomer reaction.

Thus, the stability of the obtained core portion 14 and the side cladding portion 15 can be achieved by reacting the monomers remaining in the respective regions 925 and 940.

The heating temperature of the second heat treatment is not particularly limited as long as it can activate the catalyst precursor or the promoter, and is preferably about 70 to 100 ° C, more preferably about 80 to 90 ° C.

Further, the heating time is preferably about 0.5 to 2 hours, more preferably about 0.5 to 1 hour.

Next, the third heat treatment is performed on the layer 910.

Thereby, the internal stress generated in the obtained core layer 13 can be reduced, or the core portion 14 and the side cladding portion 15 can be more stabilized.

The heating temperature of the third heat treatment is preferably set to be higher than the heating temperature of the second heat treatment by 20 ° C or higher, and specifically preferably about 90 to 180 ° C, more preferably about 120 to 160 ° C.

Further, the heating time is preferably about 0.5 to 2 hours, more preferably about 0.5 to 1 hour.

Through the above steps, the optical waveguide 1 (for example, the core layer 13) can be obtained.

In the state before the second heat treatment or the third heat treatment, for example, a sufficient refractive index difference is obtained between the core portion 14 and the side surface cladding portion 15, and the second heat treatment or the second heat treatment may be omitted. 3 heat treatment.

[3] Next, similarly to the first manufacturing method, the layers 11 and 12 are coated on the two layers of the core layer 13. Thereby, the optical waveguide 1 is obtained.

<Electronic Machine>

The optical waveguide of the present invention as described above is superior in optical transmission efficiency and long-term reliability. Therefore, by providing the optical waveguide of the present invention, it is possible to obtain a highly reliable electronic device (an electronic device of the present invention) capable of high-quality optical communication between two points.

Examples of the electronic device including the optical waveguide of the present invention include electronic devices such as mobile phones, game machines, router devices, WDM devices, personal computers, televisions, and home servers. In such an electronic device, it is necessary to transfer large-capacity data at high speed between, for example, an arithmetic device such as an LSI and a memory device such as a RAM. Therefore, by providing the optical waveguide of the present invention, such an electronic device can eliminate problems such as noise and signal deterioration peculiar to electrical wiring, and is expected to have an outstanding performance.

Further, in the optical waveguide portion, the amount of heat generation is greatly reduced as compared with the electrical wiring. Therefore, the power required for cooling can be reduced, and the power consumption of the entire electronic device can be reduced.

Further, the optical waveguide system of the present invention has a small transmission loss and a slow delay of the pulse signal, and is less likely to cause interference even after multi-frequency modulation and high density. Therefore, even if it is a high-density and small-area optical transmission path with high reliability, by mounting this optical waveguide, the reliability and miniaturization of an electronic device can be achieved.

Although the optical waveguide and the electronic device of the present invention have been described above, the present invention is not limited to this, and an arbitrary constituent may be added to, for example, the optical waveguide.

In the electronic device of the present embodiment, a device for transmitting data to a wide band by high-speed communication of large-capacity data is used as a transmission device such as a router device or a WDM (Wavelength Division Multiplexing) device. In such a transmission device, a signal processing substrate in which an LSI-like calculation element, a memory-like memory element, or the like is provided is often provided to be responsible for interconnection of the respective return lines.

The optical waveguide of the present embodiment is excellent in optical transmission characteristics such as less light loss and reduced mutual interference. Thereby, with the increase in the speed of data transmission, mutual interference, occurrence of high-frequency noise, deterioration of electrical signals, and the like can be suppressed. Therefore, data can be transmitted with high efficiency in each signal processing substrate. In addition, data can be transmitted with high efficiency in supercomputers or large-scale servers.

Further, the method for producing an optical waveguide of the present invention is not limited to the above method, and for example, a method of cutting a molecular bond by an irradiation line of actinic radiation to change a refractive index (photo-fading method), and forming a core layer may be used. The composition contains a photocrosslinkable polymer having an unsaturated bond capable of photo-metasonation or photodimerization, and is irradiated with active radiation to change the molecular structure and change the refractive index (photo-isomerization method, photodimerization) Method) and other methods.

In these methods, the amount of change in the refractive index can be adjusted in accordance with the amount of irradiation of the active radiation. Therefore, by matching the shape of the refractive index distribution W of the target, the irradiation amount of the active radiation amount irradiated to each portion of the layer is different. A core layer having a refractive index distribution W can be formed.

Further, the refractive index distribution in the thickness direction of the optical waveguide of the present invention is not particularly limited, and may be, for example, a step (SI) type distribution, a progressive (GI) type distribution, or a distribution similar to the above refractive index distribution W.

(Example)

Next, an embodiment of the present invention will be described.

1. Manufacturing of optical waveguides (Example 1) (1) has a drop-off basis Synthesis of olefinic resins

The water and oxygen concentrations are controlled below 1ppm. In a glove box filled with dry nitrogen, the hexyl reduction is measured in a 500mL glass bottle. Alkene (HxNB) 7.2g (40.1mmol), diphenylmethyl drop 12.9 g (40.1 mmol) of methoxymethoxy decane was added, and 60 g of dehydrated toluene and 11 g of ethyl acetate were added, and the sealing material prepared by coating was kneaded.

Next, 1.56 g (3.2 mmol) of the Ni catalyst represented by the following chemical formula (A) and 10 mL of dehydrated toluene were placed in a 100 mL glass vial, and the mixture was placed in a stirring piece and tightly packed, and the catalyst was sufficiently stirred to completely dissolve.

1 mL of the Ni catalyst solution represented by the following chemical formula (A) was accurately measured by a syringe, and quantitatively injected to dissolve the above two kinds of drops. The mixture was stirred at room temperature for 1 hour in an aluminum glass bottle, and as a result, a significant viscosity increase was confirmed. At this time, the cap plug was opened, and 60 g of tetrahydrofuran (THF) was added and stirred to obtain a reaction solution.

9.5 g of acetic anhydride, 18 g of hydrogen peroxide water (concentration: 30%), and 30 g of ion-exchanged water were placed in a 100 mL beaker and stirred, and an aqueous solution of acetic acid was prepared in the field. Next, the entire amount of the aqueous solution was added to the above reaction solution and stirred for 12 hours to carry out a reduction treatment of Ni.

Next, the treated reaction solution was transferred to a separatory funnel, and the lower aqueous layer was removed, and then 100 mL of a 30% aqueous solution of isopropyl alcohol was added thereto and vigorously stirred. The aqueous layer was removed after standing and completely separating the layers. After the water washing process was recombined three times, the oil layer was dropped into excess acetone to reprecipitate the formed polymer, and the filtrate was filtered by filtration, and then dried by heating in a vacuum dryer set at 60 ° C for 12 hours. Thereby, the polymer #1 was obtained. The molecular weight distribution of the polymer #1 was measured by GPC, Mw = 100,000 and Mn = 40,000. Moreover, the molar ratio of each structural unit in the polymer #1 is determined by NMR, and the hexyl group is lowered. The structural unit of the olefin is 50 mol%, and the diphenylmethyl group is lowered. The structural unit of the methoxymethoxydecane is 50 mol%.

[39]

[化40]

(2) Manufacture of a composition for forming a core layer

The purified above polymer #1 10g was weighed in a 100 mL glass vessel and added thereto. 40 g, antioxidant Irganox 1076 (manufactured by Ciba-Geigy Co., Ltd.) 0.01 g, cyclohexyloxetane monomer (first monomer represented by formula (20), CHOX manufactured by Toagosei Co., CAS#483303-25-9, Molecular weight 186, boiling point 125 ° C / 1.33 kPa) 2 g, polymerization initiator (photoacid generator) Rhodorsil Photoinitiator 2074 (manufactured by Rhodia, CAS #178233-72-2) (2.50E-2g, ethyl acetate 0.1mL After uniformly dissolving, it was filtered through a 0.2 μm PTFE filter to obtain a clean core layer-forming composition.

(3) Manufacture of optical waveguides (production of the lower cladding layer)

Uniform coating of the photoresist on the wafer The olefin resin composition (Avatrel 2000P varnish manufactured by Promerus Co., Ltd.) was placed in a dryer at 45 ° C for 15 minutes. After the solvent was completely removed, the coated surface was irradiated with ultraviolet rays of 80 mJ, and heated in a dryer at 120 ° C for 1 hour to cure the coating film to form a lower cladding layer. The lower side cladding layer was formed to have a thickness of 20 μm and was colorless and transparent.

(production of the core layer)

The composition for forming a core layer was uniformly applied to the lower cladding layer by a doctor blade, and then placed in a dryer at 55 ° C for 10 minutes. After the solvent was completely removed, the light-shielding mask was masked and selectively irradiated with ultraviolet rays at 1300 mJ/cm ² . The mask was removed and heated in a dryer at 150 ° C for 1.5 hours. After heating, it was confirmed that a very sharp guide wave pattern appeared. Further, the formation of the core portion and the side cladding portion was confirmed. Furthermore, the eight core portions of the formed optical waveguide system are formed in parallel. Further, the width of the core portion was set to 50 μm, the width of the side cladding portion was set to 80 μm, and the thickness of the core layer was set to 50 μm.

(production of the upper cladding layer)

A dried film of Avatrel 2000P was laminated on a polyether enamel (PES) film in a dry thickness of 20 μm, bonded to the core layer, and placed in a vacuum laminator set at 140 ° C for hot press bonding. Thereafter, the ultraviolet ray was irradiated at 100 mJ in total and heated at 120 ° C for 1 hour in a dryer to cure Avatrel 2000P to form an upper cladding layer, thereby obtaining an optical waveguide.

Further, from the obtained optical waveguide, a portion having a length of 10 cm was cut out.

(evaluation of refractive index distribution)

Further, with respect to the cross section of the core layer of the obtained optical waveguide, the refractive index distribution in the width direction was obtained using an interference microscope along the center line in the thickness direction. As a result, the refractive index distribution has a minimum value and a maximum value of the complex number, and the refractive index changes continuously.

The measurement method using the refractive index distribution of an interference microscope is shown below.

First, the optical waveguide is sliced in the cross-sectional direction of the optical waveguide to obtain an optical waveguide fragment. The slice was sliced so that the length of the optical waveguide was 200 μm to 300 μm. Next, a chamber filled with oil having a refractive index of 1.536 was formed in a space surrounded by two glass slides. In the space in the chamber, the optical waveguide segment is broken into a measurement sample, and a blank sample is not inserted into the optical waveguide segment. Next, using a interference microscope, a dry crepe photograph of the cross section of the optical waveguide chip was obtained. Thereafter, image analysis of the interference pattern photograph is performed to obtain a refractive index distribution. Here, the image analysis of the interference pattern photograph is performed as follows. First, the length of the light path of the interference microscope is changed, and the image data of the occurrence of the interference pattern is continuously obtained. The refractive index of each measurement point in the interlayer direction and the in-layer direction was calculated from a plurality of image data. In the present embodiment, the interval between the measurement points was set to 2.5 μm.

(Example 2)

An optical waveguide was obtained in the same manner as in Example 1 except that the amount of ultraviolet irradiation was increased to 1,500 mJ/cm ² .

(Example 3)

In addition to increasing the amount of ultraviolet irradiation to 2000 mJ/cm ² , the molar ratio of each structural unit of the polymer #1 as a polymer was changed to a hexyl group. The olefin structural unit is 40 mol%, diphenylmethyl drop An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxydecane was 60 mol%.

(Example 4)

In addition to reducing the amount of ultraviolet irradiation to 500 mJ/cm ² , the molar ratio of each structural unit of the polymer #1 as a polymer was changed to a hexyl group. The structural unit of the olefin is 45 mol%, and the diphenylmethyl group is lowered. An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxydecane was 55 mol%.

(Example 5)

In addition to changing the molar ratio of each structural unit of polymer #1 as a polymer to a hexyl group The structural unit of the olefin is 30 mol%, and the diphenylmethyl group is lowered. An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxydecane was 70 mol%.

(Example 8)

In addition to reducing the amount of ultraviolet irradiation to 300 mJ/cm ² , the molar ratio of each structural unit of the polymer #1 as a polymer was changed to a hexyl group. The olefin structural unit is 40 mol%, diphenylmethyl drop An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxydecane was 60 mol%.

(Example 9)

In addition to reducing the amount of ultraviolet irradiation to 500 mJ/cm ² , the molar ratio of each structural unit of the polymer #1 as a polymer was changed to a hexyl group. The structural unit of the olefin is 30 mol%, and the diphenylmethyl group is lowered. An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxydecane was 70 mol%.

(Embodiment 10)

In addition to reducing the amount of ultraviolet irradiation to 100 mJ/cm ² , the molar ratio of each structural unit of the polymer #1 as a polymer was changed to a hexyl group. The structural unit of the olefin is 60 mol%, and the diphenylmethyl group is lowered. An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxydecane was 40 mol%.

(Example 11)

In addition to increasing the amount of ultraviolet irradiation to 1500 mJ/cm ² , the molar ratio of each structural unit of the polymer #1 as a polymer was changed to a hexyl group. The structural unit of the olefin is 10 mol%, and the diphenylmethyl group is lowered. An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxydecane was 90 mol%.

(Embodiment 12)

In addition to increasing the amount of ultraviolet irradiation to 3000 mJ/cm ² , the molar ratio of each structural unit of the polymer #1 as a polymer was changed to a hexyl group. The structural unit of the olefin is 5 mol%, and the diphenylmethyl group is lowered. An optical waveguide was obtained in the same manner as in Example 1 except that the structural unit of the methoxymethoxy decane was 95 mol%.

(Example 13)

An optical waveguide was obtained in the same manner as in Example 1 except that the manufacturer was used as the core layer-forming composition.

Weigh the refined polymer #1 10g in a 100mL glass container and add it to it. 40 g, an antioxidant Irganox 1076 (manufactured by Ciba-Geigy Co., Ltd.), 0.01 g, a bifunctional oxetane monomer (manufactured by the formula (15), manufactured by Toagosei Co., Ltd., DOX, CAS #18934-00-4, molecular weight 214, 2 g of a boiling point of 119 ° C / 0.67 kPa), a photoacid generator Rhodorsil Photoinitiator 2074 (manufactured by Rhodia Co., Ltd., CAS #178233-72-2) (1.36E-2 g, ethyl acetate 0.1 mL) was uniformly dissolved, and then 0.2. The μm PTFE filter was filtered to obtain a clean core layer forming composition.

(Example 14)

An optical waveguide was obtained in the same manner as in Example 1 except that the manufacturer was used as the core layer-forming composition.

Weigh the refined polymer #1 10g in a 100mL glass container and add it to it. 40 g, antioxidant Irganox 1076 (manufactured by Ciba-Geigy Co., Ltd.) 0.01 g, alicyclic epoxy monomer (manufactured by formula (37), manufactured by Daicel Chemical Co., Ltd., CELLOXIDE 2021P, CAS #2386-87-0, molecular weight 252, boiling point 2 g of 188 ° C / 4 hPa), a photoacid generator Rhodorsil Photoinitiator 2074 (manufactured by Rhodia Co., Ltd., CAS #178233-72-2) (1.36E-2 g, ethyl acetate 0.1 mL) was uniformly dissolved, and then 0.2 μm was used. The PTFE filter was filtered to obtain a clean core layer-forming composition.

(Example 15)

An optical waveguide was obtained in the same manner as in Example 1 except that the manufacturer was used as the core layer-forming composition.

Weigh the refined polymer #1 10g in a 100mL glass container and add it to it. 40 g, an antioxidant Irganox 1076 (manufactured by Ciba-Geigy Co., Ltd.), 0.01 g, a cyclohexyloxetane monomer (shown in Formula 20, CHOX, manufactured by Toagosei Co., Ltd.), 1 g, and an alicyclic epoxy monomer (manufactured by Daicel Chemical Co., Ltd.) CELLOXIDE 2021P) 1g, photoacid generator Rhodorsil Photoinitiator 2074 (manufactured by Rhodia Co., Ltd., CAS #178233-72-2) (1.36E-2g, ethyl acetate 0.1mL) was uniformly dissolved, and filtered by 0.2 μm of PTFE. The device was filtered to obtain a clean core layer forming composition.

(Embodiment 16)

An optical waveguide was obtained in the same manner as in Example 1 except that the polymer was synthesized as a polymer by the method shown below.

First, in addition to replacing the diphenylmethyl group Ethyl methoxy decane 12.9 g (40.1 mmol) using phenyl dimethyl The polymer was synthesized in the same manner as in Example 1 except that 10.4 g (40.1 mmol) of the methoxymethoxy decane was used. The structural unit of the obtained polymer is shown in the following formula (103). The molecular weight distribution of this polymer was measured by GPC, Mw = 110,000 and Mn = 50,000. Moreover, the Mohr ratio of each structural unit is determined by NMR, and the hexyl group is lowered. The olefin structural unit is 50 mol%, and the phenyl dimethyl group is lowered. The structural unit of the methoxymethoxydecane is 50 mol%.

(Example 17)

The core layer forming composition was uniformly applied to the lower cladding layer by a doctor blade, and was put into a 60 ° C dryer for 10 minutes, except that the composition was formed by the method shown below. The same procedure as in Example 1 was carried out to obtain an optical waveguide.

Weigh the refined polymer #1 10g in a 100mL glass container and add it to it. 40 g, antioxidant Irganox 1076 (manufactured by Ciba-Geigy Co., Ltd.) 0.01 g, cyclohexyloxetane monomer (shown by formula (20), CHOX manufactured by Toagosei Co., Ltd.) 2 g, photoacid generator Rhodorsil Photoinitiator 2074 (Rhodia Corporation) The system was prepared by uniformly dissolving it in a solution of 2.72E-2g (ethyl acetate, 0.1 mL), and filtering it through a 0.2 μm PTFE filter to obtain a clean core layer-forming composition.

(Embodiment 18)

An optical waveguide was obtained in the same manner as in Example 15 except that the amount of ultraviolet irradiation was reduced to 500 mJ/cm ² .

[化41]

(Comparative Example 1)

An optical waveguide was obtained in the same manner as in Example 1 except that the following was carried out.

First, after the lower cladding layer is formed, a composition for forming a core layer obtained by omitting a cyclohexyloxetane monomer from the polymer #1 is applied thereon, and exposed and heated to obtain a core layer.

Thereafter, an optical waveguide is obtained by forming the upper cladding layer.

Further, in the obtained optical waveguide, the refractive index of the core portion is almost constant, and the refractive index of the side cladding portion is also almost constant. That is, the refractive index distribution of the core layer of the obtained optical waveguide is a so-called step type.

(Comparative Example 2)

An optical waveguide was obtained in the same manner as in Comparative Example 1, except that the exposure amount was continuously changed during exposure, and the light transmittance was continuously changed.

Further, in the obtained optical waveguide, the refractive index of the side cladding portion is almost constant; on the other hand, the refractive index of the core portion is continuously reduced from the central portion toward the periphery. That is, the refractive index distribution of the core layer of the obtained optical waveguide becomes a so-called progressive type.

(Comparative Example 3)

An optical waveguide was obtained in the same manner as in Comparative Example 1, except that the exposure amount was continuously changed during exposure, and the light transmittance was continuously changed.

Further, in the obtained optical waveguide, the refractive index distribution has a minimum value and a maximum value of the complex number, and the refractive index of the core portion decreases continuously from the central portion toward the periphery to a minimum value; on the other hand, in the side cladding portion, The refractive index increases continuously as it moves away from the minimum value. Further, in the minimum value, the shape of the refractive index distribution is formed in a substantially V shape, and the change in the refractive index in the vicinity thereof is discontinuous.

2. Evaluation 2.1 refractive index distribution of optical waveguide

The cross-sectional profile of the core layer of the obtained optical waveguide was carried out in the same manner as the above method using the interference microscope along the center line in the thickness direction thereof to obtain a refractive index distribution. Further, since the obtained refractive index distribution repeats the same refractive index distribution pattern for each core portion, a part of the obtained refractive index distribution is cut out as the refractive index distribution W. The shape of the refractive index distribution W is a shape in which four minimum values and five maximum values are alternately arranged as shown in FIG. 2 .

Then, from the obtained refractive index distribution W, the minimum values Ws1, Ws2, Ws3, and Ws4 and the respective maximum values Wm1, Wm2, Wm3, Wm4, and Wm5 are obtained, and the average refractive index WA of the cladding portion is obtained.

Further, in the refractive index distribution W, the refractive index formed in the vicinity of the maximum values Wm2 and Wm4 of the core portion is a width a [μm] of a portion having a value equal to or higher than the average refractive index WA, and each minimum value Ws1, Ws2. The refractive index in the vicinity of Ws3 and Ws4 is a width b [μm] of a portion having a WA value which is less than the average refractive index.

As a result, the refractive index distribution W of the optical waveguide obtained in each of the examples was continuous in the refractive index change of the whole. Further, in the examples, the refractive index distribution P including the first cladding layer, the cladding portion, and the cladding layer was of the SI type.

On the other hand, the refractive index distribution of the optical waveguide obtained in Comparative Example 1 was a step type as described above.

Further, the refractive index distribution of the optical waveguide obtained in Comparative Example 2 was a progressive type as described above.

Further, the refractive index distribution of the optical waveguide obtained in Comparative Example 3 was such that the refractive index of the core portion and the side cladding portion were discontinuously changed.

2.2 Transmission loss of optical waveguide

The light emitted by the 850 nm VCSEL (surface-emitting laser) was introduced into the obtained optical waveguide via a 50 μm-twisted optical fiber, and the light was measured by an optical fiber of 200 μm, and the light intensity was measured. Further, a back-cut method was used for the measurement. The longitudinal direction of the optical waveguide is taken as the horizontal axis, and the insertion loss is taken as the vertical axis, and the measured values are plotted. As a result, the measured values are arranged on a straight line. Thereby, the transmission loss is calculated from the slope of the straight line.

2.3 Waveform signal retention

For the obtained optical waveguide, a pulse signal having a pulse width of 1 ns is incident from the laser pulse source, and the pulse width of the emitted light is measured.

Then, the relative value when the measured value of the optical waveguide (step type optical waveguide) obtained in Comparative Example 1 was set to 1 was calculated for the pulse width of the measured emitted light, and was evaluated based on the following evaluation criteria.

<Pulse width evaluation criteria>

◎: The relative value of the pulse width is less than 0.5

○: The relative value of the pulse width is 0.5 or more and less than 0.8.

△: The relative value of the pulse width is 0.8 or more and less than 1

╳:: The relative value of the pulse width is 1 or more

The evaluation results of 2.2 and 2.3 are shown in Table 1.

As shown in Table 1, it was confirmed that the optical waveguides obtained in the respective examples were suppressed in transmission loss and pulse signal delay compared to the optical waveguides obtained in the respective comparative examples. Further, in the coating portion of the embodiment, the transmission loss and the delay of the pulse signal are different from those of the first cladding layer, the cladding portion, and the second cladding layer, respectively. Suppressed.

2.4 Intensity distribution of the light emitted by the optical waveguide

The intensity distribution of the emitted light when one of the eight core portions was incident on the light was measured for the output side end surface of the obtained optical waveguide.

Further, the measurement of the intensity distribution of the emitted light was carried out as follows.

FIG. 10 is a view for explaining a method of measuring the intensity distribution of the emitted light in the end surface on the emission side of the optical waveguide.

In the method shown in FIG. 10, first, the incident side optical fiber 21 having a diameter of 50 μm is disposed so as to face one of the core portions 14 of the incident side end surface 1a of the optical waveguide 1 to be measured. The incident-side optical fiber 21 is connected to a light-emitting element (not shown) for causing light to enter the optical waveguide 1, and its optical axis and the optical axis of the core portion 14 are arranged to coincide with each other.

On the other hand, on the emission-side end surface 1b of the optical waveguide 1, an emission-side optical fiber 22 having a diameter of 62.5 μm is disposed so as to face the same. The emission side optical fiber 22 is connected to a light receiving element (not shown) for receiving the light emitted from the optical waveguide 1, and its optical axis is aligned with the center line in the thickness direction of the core layer of the optical waveguide 1. Then, the distance between the exit side optical fiber 22 and the emission side end surface 1b is kept constant, and the configuration is such that the inside surface including the center line can be scanned.

Then, light is incident on one of the core portions by the incident-side optical fiber 21, and the output-side optical fiber 22 is scanned. Then, by measuring the intensity of the emitted light measured by the light-receiving element on the position of the output-side optical fiber 22, the intensity distribution of the position of the emitted light on the output-side end surface 1b can be obtained.

Fig. 11 shows the intensity distribution of the emitted light as measured above. Further, in Fig. 11, the intensity distribution of the emitted light measured by the optical waveguides obtained in Example 1, Comparative Example 1, and Comparative Example 2 is representatively shown.

As is clear from Fig. 11, in the optical waveguide obtained in the first embodiment, mutual interference is sufficiently suppressed. Further, in the optical waveguide obtained in the first embodiment, it is confirmed that the intensity of the emitted light in the core portion 14 adjacent to the core portion 14 through which the light is incident (the core portion 14 in the center of FIG. 11) is smaller than the adjacent The intensity of the emitted light in the side cladding portion 15 of the core portion 14 on the side opposite to the core portion 14 through which the light is incident. In this case, it is inferred that in the optical waveguide obtained in the first embodiment, the side cladding portion 15 has a maximum value smaller than the value of the core portion 14, and the refractive index distribution changes continuously, so that it leaks to the adjacent core in the prior art. The light that becomes "interference" in the portion 14 is concentrated on the side cladding portion 15, and as a result, mutual interference is prevented from occurring. Therefore, in the optical waveguide obtained in the first embodiment, interference between channels can be prevented.

Further, in the optical waveguide obtained in the first embodiment, it is observed that one of the emitted light is concentrated on the side cladding portion 15, but generally, the light receiving elements connected to the optical waveguide are connected to the exit side end faces of the respective core portions 14. It is opposed to each other and is not connected to the side cladding portion 15. Therefore, even if light is concentrated to the side cladding portion 15, mutual interference does not occur, and interference is suppressed.

Further, although not illustrated, in the optical waveguide obtained by the other embodiments, mutual interference is sufficiently suppressed as in the first embodiment.

On the other hand, in the optical waveguides obtained in Comparative Examples 1 and 2, in the core portion 14 adjacent to the core portion 14 of the incident light, there is a maximum value of the intensity distribution of the emitted light, and light leakage is observed ( Mutual interference).

Further, although not shown, mutual interference was also observed in the optical waveguide obtained in Comparative Example 3.

(3. Other embodiments) 3.1 Manufacturing of optical waveguides (Example A) (1) Manufacturing of coating solution

CELLOXIDE2081 20g manufactured by Daicel Chemical Industry Co., Ltd., 0.6g of ADEKA OPTOMER SP-170 manufactured by ADEKA Co., Ltd., and 80g of methyl isobutyl ketone were stirred and mixed, and filtered by a PTFE filter having a pore size of 0.2 μm to obtain a clean and colorless product. Transparent coating solution E1.

(2) Manufacture of photosensitive resin composition

YP-50S 20g manufactured by Nippon Steel Chemical Co., Ltd., CELLOXIDE 2021P 5g manufactured by Daicel Chemical Industry Co., Ltd., and 0.2 g of ADEKA OPTOMER SP-170 manufactured by ADEKA Co., Ltd. were placed in 80 g of methyl isobutyl ketone, and stirred and dissolved. Filtration was carried out by a PTFE filter having a pore size of 0.2 μm to obtain a clear and colorless transparent photosensitive resin composition F1.

(3) Production of the lower layer coating

The coating solution E1 was uniformly applied onto a 25 μm thick polyimine film by a doctor blade, and then placed in a dryer at 50 ° C for 10 minutes. After the solvent was completely removed, the entire surface was irradiated with ultraviolet rays at 500 mJ/cm ² by a UV exposure machine to be hardened to form a colorless and transparent undercoat. The resulting coating layer had a thickness of 10 μm.

(4) Formation of the core layer, patterning of the core area and the cladding area

The photosensitive resin composition F1 was uniformly applied by the doctor blade on the lower layer coating, and then placed in a dryer at 50 ° C for 10 minutes. After the solvent was completely removed, a light mask having a linear pattern of 50 μm in line and 50 μm in pitch was drawn on the entire surface, and ultraviolet rays were irradiated with a dose of 500 mJ/cm ² using a parallel exposure machine. Thereafter, the mask was removed, placed in an oven at 150 ° C for 30 minutes, and taken out, and it was confirmed that a clear waveguide pattern appeared. The resulting core layer had a thickness of 50 μm.

(5) Formation of the upper layer coating

On the core layer, the coating solution E1 was used to form an upper layer coating under the same conditions as the under layer coating. The resulting upper layer was coated to a thickness of 10 μm.

(Example B) (1) Synthesis of polymers

20.0 g of methyl methacrylate, 30.0 g of benzyl methacrylate, and 450 g of methyl isobutyl ketone were placed in a separation flask, stirred and mixed, and then replaced with nitrogen to obtain a monomer solution. On the other hand, 0.25 g of azobisisobutyronitrile as a polymerization initiator was dissolved in 10 g of methyl isobutyl ketone, and replaced with nitrogen to obtain a starter solution. Thereafter, while stirring the above monomer solution, the mixture was heated to 80 ° C, and the above initiator solution was added to the monomer solution using a syringe. The mixture was heated and stirred at 80 ° C for 1 hour, and then cooled to obtain a polymer solution.

Next, 5 L of isopropyl alcohol was prepared in a beaker and stirred at a normal temperature with a stirrer while dropping the above polymer solution. After the completion of the dropwise addition, the mixture was stirred for 30 minutes, and then the precipitated polymer was taken out, and dried at 60 ° C for 8 hours under reduced pressure in a vacuum dryer to obtain a polymer A1.

(2) Manufacturing of coating solution

20 g of water-based acrylate resin solution RD-180, 20 g of isopropyl alcohol and 0.4 g of CARBODILITE V-02-L2 manufactured by Nisshin Chemical Co., Ltd., and a PTFE filter with a pore size of 0.2 μm. Filtration was carried out to obtain a clear and colorless transparent coating solution B1.

(3) Manufacture of photosensitive resin composition

20 g of the polymer A1 obtained by the method (1), 5 g of cyclohexyl methacrylate and 0.2 g of Irgacure 651 manufactured by BASF Japan Co., Ltd. were placed in 80 g of methyl isobutyl ketone and stirred and dissolved, and a pore size of 0.2 μm was used. The PTFE filter was filtered to obtain a clear, colorless and transparent photosensitive resin composition C1.

(4) Production of the lower layer coating

The coating solution B1 was uniformly applied onto a 25 μm thick polyimine film by a doctor blade, and then placed in a dryer at 80 ° C for 10 minutes. After the solvent was completely removed, it was further poured into an oven at 150 ° C for 10 minutes to be hardened to obtain a colorless transparent underlayer coating. The resulting coating layer had a thickness of 10 μm.

(5) Patterning of the core layer, core area and cladding area

The photosensitive resin composition C1 was uniformly applied by the doctor blade on the lower layer coating, and then placed in a dryer at 50 ° C for 10 minutes. After the solvent was completely removed, a light mask having a linear pattern of 50 μm in line and 50 μm in pitch was drawn on the entire surface, and ultraviolet rays were irradiated with a dose of 500 mJ/cm ² using a parallel exposure machine. Thereafter, the mask was removed, placed in a nitrogen dryer at 150 ° C for 30 minutes, and taken out, and it was confirmed that a clear waveguide pattern appeared. The resulting core layer had a thickness of 50 μm.

(6) Formation of the upper layer coating

On the core layer, the coating solution B1 was used to form an upper layer coating under the same conditions as the lower layer coating. The resulting upper layer was coated to a thickness of 10 μm.

(Example C)

First, the synthesized polymer A2 was obtained in the same manner as in the above (1) except that 2-(perfluorohexyl)ethyl methacrylate was used instead of the benzyl methacrylate.

In the same manner as in Example B, except that the polymer A2 was used instead of the polymer A1, an optical waveguide was obtained.

3.2 Evaluation (transmission loss of optical waveguide)

Light emitted from an 850 nm VCSEL (surface-emitting laser) was introduced into the optical waveguide obtained in Examples A to C through an optical fiber having a diameter of 50 μm, and light was received by an optical fiber having a diameter of 200 μm to measure the light intensity. Then, the transmission loss is determined by the back-cut method. Then, the waveguide length was plotted on the horizontal axis and the insertion loss was plotted on the vertical axis. As a result, the measured values were arranged on a straight line, and the transmission loss of each optical waveguide was calculated to be 0.05 dB/cm from the slope.

Further, in Examples A to C, the parameters of the refractive index distribution were changed to be the same as those of the example of 1. As a result, the evaluation results of the same tendency as 2. were obtained.

(Retention of waveform of pulse signal)

With respect to the optical waveguides obtained in Examples A to C, the waveform retention of the pulse signals was evaluated in the same manner as in 2.3, and as a result, it was confirmed that the jitter of any of the pulse signals was small.

Further, in Examples A to C, the parameters of the refractive index distribution were changed to be the same as those of the example of 1. As a result, the evaluation results of the same tendency as 2. were obtained.

(Comparative Example 4) (1) has a drop-off basis Synthesis of olefinic resins

In a glove box filled with dry nitrogen and nitrogen and water concentrations controlled to less than 1 ppm, the hexyl group is measured in a 500 mL glass bottle. Alkene (HxNB) 7.2g (40.1mmol), diphenylmethyl drop 12.9 g (40.1 mmol) of methoxymethoxy decane was added, and 60 g of dehydrated toluene and 11 g of ethyl acetate were added, and the sealing material prepared by coating was kneaded.

Next, 1.56 g (3.2 mmol) of the Ni catalyst represented by the following formula (4) and 10 mL of dehydrated toluene were measured in a 100 mL glass vial, placed in a stirring piece, and the mixture was tightly packed, and the catalyst was thoroughly stirred to completely dissolve.

1 mL of the Ni catalyst solution represented by the chemical formula (A) was accurately measured by a syringe, and quantitatively injected to dissolve the above two kinds of drops. The mixture was stirred at room temperature for 1 hour in an aluminum glass bottle, and as a result, a significant viscosity increase was confirmed. At this time, the cap plug was opened, and 60 g of tetrahydrofuran (THF) was added and stirred to obtain a reaction solution.

9.5 g of acetic anhydride, 18 g of hydrogen peroxide water (concentration: 30%), and 30 g of ion-exchanged water were placed in a 100 mL beaker and stirred to prepare an aqueous solution of acetic acid. Next, the entire amount of the aqueous solution was added to the above reaction solution and stirred for 12 hours to carry out a reduction treatment of Ni.

Next, the treated reaction solution was transferred to a separatory funnel, and the lower aqueous layer was removed, and then 100 mL of a 30% aqueous solution of isopropyl alcohol was added thereto and vigorously stirred. The aqueous layer was removed after standing and completely separating the layers. After the water washing process was recombined three times, the oil layer was dropped into excess acetone to reprecipitate the formed polymer, and the filtrate was filtered by filtration, and then dried by heating in a vacuum dryer set at 60 ° C for 12 hours. Thereby obtaining a drop-off basis in the side chain Alkene resin A (Polymer #1). drop The molecular weight distribution of the olefinic resin A is determined by GPC, Mw = 100,000, Mn = 40,000, The molar ratio of each structural unit in the olefinic resin A is determined by NMR, and the hexyl group is lowered. The structural unit of the olefin is 50 mol%, and the diphenylmethyl group is lowered. The structural unit of the methoxymethoxydecane is 50 mol%. Further, the refractive index was 1.55 (measurement wavelength: 633 nm) as measured by Metricon.

[化42]

[化43]

(2) Modulation of photosensitive resin composition

Weighed and refined in a 100mL glass container Ethylene resin A 10g, added to it 40 g, antioxidant Irganox 1076 (manufactured by Ciba-Geigy Co., Ltd.) 0.01 g, cyclohexyloxetane monomer (first monomer represented by formula (20), CHOX manufactured by Toagosei Co., CAS#483303-25-9, 2 g of molecular weight 186, boiling point 125 ° C / 1.33 kPa), photoacid generator Rhodorsil Photoinitiator 2074 (manufactured by Rhodia Co., Ltd., CAS #178233-72-2) (1.36E-2 g, ethyl acetate 0.1 mL) and uniformly dissolved Thereafter, the mixture was filtered through a 0.2 μm PTFE filter to prepare a photosensitive resin composition varnish V1 for the clean core layer.

(3) Manufacture of optical waveguides (production of the lower side cladding)

Uniform coating of the photoresist on the wafer The olefin resin composition (Avatrel 2000P varnish manufactured by Promerus Co., Ltd.) was placed in a dryer at 45 ° C for 15 minutes. After the solvent was completely removed, the coated surface was irradiated with ultraviolet rays of 100 mJ, and heated at 120 ° C for 1 hour in a dryer to cure the coating film to form a lower layer coating. The underlying layer was formed to have a thickness of 20 μm, was colorless and transparent, and had a refractive index of 1.52 (measurement wavelength: 633 nm).

(production of core area and cladding area)

The photosensitive resin composition varnish V1 obtained by uniformly coating and coating the lower layer coating with a doctor blade was placed in a dryer at 45 ° C for 15 minutes. After the solvent was completely removed, the light-shielding mask was masked and selectively irradiated with ultraviolet rays at 500 mJ/cm ² . The mask was removed and heated in a dryer at 30 ° C for 30 minutes, 85 ° C for 30 minutes, and 150 ° C for 1 hour. After heating, it was confirmed that a core layer having a very distinct waveguide pattern appeared.

(production of the upper layer coating)

On the polyether enamel (PES) film, the photosensitive layer is preliminarily deposited in a dry thickness of 20 μm. The olefin resin composition (Avatrel 2000P varnish manufactured by Promerus Co., Ltd.) was used to obtain a film for coating an upper layer.

(production of optical waveguides)

The core layer formed on the lower cladding layer is bonded to the film for coating the upper layer, and is placed in a vacuum laminator set at 140 ° C for thermal compression bonding, and then irradiated with ultraviolet rays at 100 mJ in a dryer. After heating at 120 ° C for 1 hour, Avatrel 2000P was hardened to form an upper layer coating to obtain an optical waveguide.

It was confirmed that the refractive index distribution in the in-layer direction of the core layer of the optical waveguide of Comparative Example 4 was not W-type.

This embodiment includes the following.

The refractive index of the top of the first recess may be smaller than the average refractive index of the cladding portion.

The refractive index distribution W may have a top portion of the second convex portion other than the vicinity of the boundary between the first core portion and the cladding portion.

The refractive index distribution W may have a top portion of the second convex portion at the center portion of the cladding portion, and a region in which the refractive index is continuously reduced from the top of the second convex portion toward the first concave portion. The refractive index difference between the first core portion and the first cladding layer in the refractive index distribution T may be larger than the refractive index difference between the top portion of the first concave portion and the top portion of the first convex portion in the refractive index distribution W. Here, as the refractive index of the top portion, a maximum value or a refractive index at the central portion of the flat portion can be used.

The hole may be provided to pass through the first core portion and the first cladding layer, and the inner surface of the hole may constitute a reflection surface for reflecting the light transmitted by the core portion.

The difference between the refractive index at the top of the first concave portion and the average refractive index in the cladding portion may be 3 to 80% of the difference between the refractive index at the top of the first concave portion and the refractive index at the top of the first convex portion.

The difference in refractive index between the refractive index at the top of the first concave portion and the refractive index at the top of the first convex portion may be 0.005 to 0.07.

In the refractive index distribution W, the width of the portion where the refractive index of the first convex portion has a value equal to or greater than the average refractive index in the coating portion is a [μm], and the refractive index of the first concave portion is not covered. When the width of the value of the average refractive index in the portion is b [μm], b may be 0.01a to 1.2a.

Furthermore, the present embodiment described below is included.

(1) An optical waveguide having a core portion and a cladding portion adjacent to at least two side surfaces of the core portion, wherein the refractive index distribution of the optical waveguide has a minimum refractive index distribution of at least two minimum values At least one first maximum value and at least two second maximum values smaller than the first maximum value, and having the second maximum value, the minimum value, the first maximum value, the minimum value, and the second maximum a region in which the values are sequentially arranged; wherein the region including the first maximum value and held by the two minimum values is the core portion, and the region from the minimum value to the second maximum value side is The coating portion; each of the minimum values is less than an average refractive index in the coating portion, and the refractive index changes continuously in the entire refractive index distribution.

(2) The optical waveguide of (1), wherein, in the refractive index distribution, the second maximum value is located outside the interface between the core portion and the region corresponding to the cladding portion.

(3) The optical waveguide of (2), wherein, in the refractive index distribution, in the region corresponding to the covering portion, the second maximum value is located at a central portion of the region, and the refractive index is from the second maximum The value changes in such a manner that the above-mentioned minimum value continuously decreases.

(4) The optical waveguide of any one of (1) to (3), wherein a difference between the minimum value and an average refractive index in the coating portion is a difference between the minimum value and the first maximum value 3~80%.

(5) The optical waveguide of (4), wherein a difference in refractive index between the minimum value and the first maximum value is 0.005 to 0.07.

(6) The optical waveguide according to any one of (1) to (5) wherein, when the position of the cross section is the horizontal axis and the refractive index of the cross section is the vertical axis, the refractive index distribution is A convex U-shape is formed in the vicinity of the first maximum value, and a convex U-shape is formed downward in the vicinity of the minimum value.

(A) The optical waveguide of any one of (1) to (6), wherein, in the refractive index distribution, a refractive index in the vicinity of the first maximum value has a value equal to or greater than an average refractive index in the coating portion. When the width of the portion is set to a [μm], and the width of the refractive index in the vicinity of the minimum value is less than the value of the average refractive index in the cladding portion, b [μm], b is 0.01a to 1.2. a.

The optical waveguide of any one of (1) to (7), wherein the optical waveguide has a plurality of core portions and the cladding portions adjacent to at least two side faces of the core portions.

(9) The optical waveguide of any one of (1) to (8), wherein the core portion is lowered It is composed of an olefinic resin.

(10) An electronic device comprising the optical waveguide of any one of (1) to (9) above.

Priority is claimed on the basis of Japanese Patent Application No. 2010-191293, filed on Jan. 27, 2011, the entire disclosure of which is incorporated herein.

1. . . Optical waveguide

1a. . . Injection side end face

1b. . . Injection side end face

2. . . Support film

3. . . Cover film

11,12. . . Coating

13. . . Core layer

14. . . Core department

15. . . Covering part

twenty one. . . Injection side fiber

twenty two. . . Injection side fiber

141, 142. . . Core department

151, 152, 153. . . Side cladding

900. . . Core layer forming composition

910. . . Floor

915. . . polymer

920. . . additive

925. . . Irradiated area

930. . . Active radiation

935. . . Mask

9351. . . Opening (window)

940. . . Unirradiated area

951. . . Support substrate

952. . . Support substrate

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing an embodiment (partially cut and penetrated) of an optical waveguide of the present invention.

FIG. 2 is a schematic view showing an example of a refractive index distribution when the position of the center line of the thickness of the core layer is the horizontal axis and the refractive index is the vertical axis in the X-X line cross-sectional view shown in FIG. 1 .

Fig. 3 is a view showing an example of an intensity distribution of emitted light when light is incident on one of the core portions of the optical waveguide shown in Fig. 1;

Fig. 4 is a view for explaining a first manufacturing method of the optical waveguide shown in Fig. 1;

Fig. 5 is a view for explaining a first manufacturing method of the optical waveguide shown in Fig. 1;

Fig. 6 is a view for explaining a first manufacturing method of the optical waveguide shown in Fig. 1;

Fig. 7 is a view for explaining a first manufacturing method of the optical waveguide shown in Fig. 1;

Fig. 8 is a view for explaining a first manufacturing method of the optical waveguide shown in Fig. 1;

FIG. 9 is a view for explaining a case where a refractive index difference is generated between an irradiation region and a non-irradiation region, and is a refractive index when the position of the cross section of the layer is the horizontal axis and the refractive index of the cross section is the vertical axis. Distributed map.

FIG. 10 is a view for explaining a method of measuring the intensity distribution of the emitted light in the end surface on the emission side of the optical waveguide.

FIG. 11 is a view showing the intensity distribution of the emitted light in the end surface on the emission side of the optical waveguide obtained in Example 1, Comparative Example 1, and Comparative Example 2. FIG.

1. . . Optical waveguide

2. . . Support film

3. . . Cover film

11. . . Coating

12. . . Coating

13. . . Core layer

14. . . Core department

15. . . Covering part

141. . . Core department

142. . . Core department

151. . . Side cladding

152. . . Side cladding

153. . . Side cladding

Claims (12)

An optical waveguide comprising: a first cladding layer; the core layer is provided on the first cladding layer, and has a cladding portion, a first core portion, and a cladding portion provided in the layer inner direction in this order The second core portion and the cladding portion; and the second cladding layer are disposed on the core layer; wherein the core layer includes an in-layer direction of the portion of the first core portion and the cladding portion The refractive index distribution W is continuously changed, and has a region in which the first convex portion, the first concave portion, and the second convex portion are arranged in order; and the refractive index distribution W located in the first core portion has the first convex portion The refractive index distribution W located in the coating portion has the second convex portion having a refractive index maximum value smaller than the first convex portion, and includes the first cladding layer, the coating portion, and the second cladding portion The refractive index distribution P in the interlayer direction of the layer is different between the portion located in the first cladding layer and the portion located in the cladding portion, and the refractive index distribution W includes the length direction of the optical waveguide form. The optical waveguide of claim 1, wherein the refractive index distribution T in the interlayer direction of the portion including the first cladding layer and the first core portion is different from the refractive index distribution W. The optical waveguide of claim 1, wherein a refractive index difference between a maximum refractive index of the first core portion and a maximum refractive index of the first cladding layer is greater than a refractive index of the first core portion The refractive index difference between the maximum value and the maximum refractive index of the above-mentioned cladding portion. An optical waveguide according to claim 1, wherein the second core layer is provided on the second cladding layer and is different from the core layer; and the second core layer is located in the first core The third core of the department in the direction of the layer. The optical waveguide of claim 1, wherein a refractive index of a top portion of the first concave portion is smaller than an average refractive index of the coating portion. The optical waveguide according to the first aspect of the invention, wherein the refractive index distribution W is a top portion of the second convex portion other than the vicinity of an interface between the first core portion and the cladding portion. The optical waveguide of claim 1, wherein the refractive index distribution W is provided at a top portion of the covering portion and has a top portion of the second convex portion, and is formed from the top portion of the second convex portion toward the first portion 1 The recess has a region in which the refractive index is continuously reduced. The optical waveguide of claim 1, wherein a difference between a refractive index of a top portion of the first concave portion and an average refractive index of the coating portion is a refractive index of a top portion of the first concave portion and the first convex portion The difference in refractive index at the top of the part is 3 to 80%. For example, the optical waveguide of claim 1 of the patent scope, wherein the first concave The refractive index difference between the refractive index at the top of the portion and the refractive index at the top of the first convex portion is 0.005 to 0.07. The optical waveguide of claim 1, wherein the refractive index distribution W has a width of a portion in which the refractive index of the first convex portion has a value equal to or greater than an average refractive index of the coating portion. When μm] and the refractive index of the first concave portion having a value lower than the average refractive index in the coating portion is b [μm], b is 0.01 a to 1.2 a. An optical waveguide having a core portion and a cladding portion adjacent to at least two side surfaces of the core portion, wherein the refractive index distribution of the optical waveguide has a minimum refractive index distribution of at least 2 And a first maximum value and at least two second maximum values smaller than the first maximum value, and having the second maximum value, the minimum value, the first maximum value, the minimum value, and the second maximum value a region in which the first maximum value is included, and the region held by the two minimum values is the core portion, and the region from the minimum value to the second maximum value is the cladding portion. The minimum value described above is less than the average refractive index in the coating portion, and the refractive index changes continuously in the entire refractive index distribution. An electronic device characterized by having an optical waveguide of any one of claims 1 to 11.