JP2003248128A - Optical coupler and manufacturing method thereof, and mixed optical and electrical wiring board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical coupler for reducing costs and easily improving coupling efficiency as compared with prior devices and a manufacturing method of the optical coupler, and to provide a mixed optical and electrical wiring board having the optical coupler and a manufacturing method of the wiring board. <P>SOLUTION: In the mixed optical electrical wiring board, a light receiving element 2 is packaged on a circuit board 1, and a flat optical waveguide 3 is formed on one surface side of the circuit board 1. The optical waveguide 3 comprises a core layer 3b, and cladding layers 3a and 3c formed on both sides in the thickness direction of the core layer 3b. A grating 7 is provided in the core layer 3b as an optical coupler for emitting light being propagated through the core layer 3b to a light receiving section 2a in the light receiving element 2. The grating 7 has a number of linear regions 7a that are regularly arranged along the propagation direction of light in the core layer 3b. Each of the linear regions 7a is formed in the core layer 3b by modifying one portion of the core layer 3b, and the line diameter is smaller than the thickness dimension of the core layer 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupler and its manufacturing method, an opto-electric hybrid wiring board and its manufacturing method.

[0002]

2. Description of the Related Art In recent years, the broadband of communication infrastructure has rapidly increased,
Along with the dramatic improvement in information processing capability of computers and the like, there is an increasing need for information processing circuits having extremely high-speed information transmission paths. Against this background, transmission by optical signals is considered as one means to break through the transmission speed limit of electric signals, and optical / electrical hybrid mounting in which optical circuits are mixedly mounted on a circuit board such as a printed circuit board. Wiring boards have been proposed.

As an optical signal transmission line constituting an optical circuit,
Optical waveguides and light guide plates are mainly used.In this type of optical circuit, a signal converted from an electrical signal to an optical signal by a light emitting element such as a laser diode is introduced into the optical signal transmission line to transmit the optical signal. It is necessary to receive an optical signal propagating along the path by a light receiving element such as a photodiode and convert the optical signal into an electric signal. Therefore, in an optical circuit, not only the transmission characteristics of the optical signal transmission line are important, but also the light from the light emitting element can be efficiently introduced into the optical signal transmission line, and the guided light of the optical signal transmission line can be efficiently combined with the light receiving element. It is important to emit it. That is, it is important to improve the coupling efficiency of the optical coupling that couples light between the optical signal transmission line and the optical device (light emitting element, light receiving element, etc.).

Usually, as a method of this kind of optical coupling, a method of inserting a reflection plate such as a mirror into the optical waveguide, or an end face of the optical waveguide is cut obliquely and reflected by utilizing a difference in refractive index from air is used. Method, a pinhole is formed inside the optical waveguide, and the functional surface of the optical device (the light emitting surface for a light emitting element,
In the case of a light receiving element, a method has been proposed in which the light receiving surface) is embedded from the end face side of the optical waveguide and directly abutted. All of these optical coupling methods are characterized by high coupling efficiency between the optical waveguide and the optical device.

Further, as an optical coupler used in an optical circuit, a grating composed of irregularities having a periodic structure of about one to one half wavelength of propagating light is known. This kind of grating is formed on the surface of the core of the optical waveguide by using the lithography method (electron beam lithography method or ultraviolet exposure lithography method) to improve the accuracy of the periodic structure. It is used for optical coupling with devices. Here, the above-mentioned grating is to increase the refractive index difference in the periodic structure as an approach for increasing the optical coupling efficiency,
Approaches such as increasing the unevenness are taken. Further, in this type of grating, a method has been proposed in which the thickness of the periodic structure is gradually changed in order to change the coupling efficiency within the same grating.

[0006]

In the opto-electric hybrid wiring board described above, a reflection plate such as a mirror is often used for optical coupling between the optical waveguide and the optical device, and high coupling efficiency can be obtained. Although it has the feature that it is possible, in order to achieve high coupling efficiency, it is essential to improve the precision of machining of workpieces such as reflectors and the precision of alignment of each component. However, it is not suitable for mass production, and there is a problem that the cost becomes high. Further, in order to downsize the opto-electric hybrid wiring board, it is necessary to downsize each component and perform highly accurate positioning, which requires time for assembly and adjustment and also increases cost.

On the other hand, the above-mentioned conventional grating has an advantage that it can be formed by utilizing a lithography method or the like and does not require high-precision assembly and adjustment. Since it is formed at the interface), there is a problem that the coupling efficiency becomes low.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical coupler which can be manufactured at a low cost and whose coupling efficiency can be easily improved as compared with the prior art, a method for manufacturing the optical coupler, and an optical coupler. An object is to provide an opto-electric hybrid wiring board having a coupler and a method for manufacturing the same.

[0009]

In order to achieve the above object, the invention of claim 1 is an optical coupler for coupling light between an optical waveguide and another optical waveguide or an optical device.
The optical waveguide core layer includes at least one grating in which a large number of fine linear regions having different refractive indexes are regularly arranged in the core layer at intervals of about the wavelength of light guided in the core layer. Is characterized in that each linear region is provided within the thickness dimension of the core layer,
Since the optical coupler is composed of a grating,
Since it is not necessary to use a reflector machined with high precision and positioning is not required for the optical waveguide when it is used for an opto-electric hybrid wiring board, cost can be reduced, and the grating is formed in the core layer. Therefore, as compared with the conventional grating formed at the interface between the core and the clad, the interaction with the guided light can be increased and the coupling efficiency can be increased, and each linear region forming the grating can be Since it is provided within the thickness of the core layer, the phase matching condition in the thickness direction of the core layer can be satisfied, and coupling with an optical device in any direction is possible only by adjusting the period of the linear region in the grating. become.

According to a second aspect of the present invention, there is provided an optical coupler for coupling light between an optical waveguide and another optical waveguide, wherein a large number of fine linear regions having a different refractive index from the core layer of the optical waveguide. Has at least one grating regularly arranged in the core layer at intervals of about the wavelength of light guided in the core layer, and the grating has each linear region provided within the thickness dimension of the core layer. Since the optical coupler is composed of a grating, it is not necessary to use a reflector plate machined with high precision and positioning with respect to the optical waveguide is unnecessary when using it for an opto-electric hybrid wiring board. Therefore, the cost can be reduced, and since the grating is formed in the core layer, the interaction with the guided light is higher than in the conventional grating formed at the interface between the core and the clad. It is possible to improve the coupling efficiency, and since each linear region forming the grating is provided within the thickness dimension of the core layer, it is possible to satisfy the phase matching condition in the thickness direction of the core layer. , The coupling with the optical device in any direction is possible only by adjusting the period of the linear region in the grating.

According to a third aspect of the present invention, in the invention of the first or second aspect, the grating is a waveguide that propagates the formation position of each of the linear regions in the core layer in the thickness direction of the core layer. Since it is matched with the position where the amplitude of the electric field of the mode light is maximized, the coupling efficiency in the optical coupler can be increased.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the optical waveguide is a multimode optical waveguide having a plurality of guided modes, and the grating is provided in the number of guided modes. Are formed at positions where the amplitude of the electric field of light in each of the guided modes is maximized in the thickness direction of the core layer, so that the coupling efficiency of the optical coupler with respect to the multimode optical waveguide can be improved. it can.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, since each of the gratings is arranged along the light propagation direction of the core layer, even if the core layer has a small thickness, each of the conductors has a small thickness. It is possible to prevent the gratings corresponding to each wave mode from overlapping or interfering with each other.

According to a sixth aspect of the present invention, in the first or second aspect of the invention, the grating forms the linear regions in the thickness direction of the core layer along the light propagation direction of the core layer. Since the intensity of the interaction with the light wave changes depending on the position along the light propagation direction, for example, when the guided light of the optical waveguide is emitted to the outside of the optical waveguide. Has the effect that the shape of the intensity distribution of spatially radiated light (light incident on an optical device or other optical waveguide) can be approximated to the shape of the intensity distribution of guided light of an optical waveguide. When the light emitted from the optical waveguide is incident on the optical waveguide, the shape of the intensity distribution of the guided light can be approximated to the shape of the intensity distribution of the spatial light, and the coupling efficiency can be improved.

The invention of claim 7 is the method for manufacturing an optical coupler according to any one of claims 1 to 6, wherein a laser beam is applied to the inside of the core layer when the grating is formed. Each of the linear regions is formed by condensing and irradiating to modify a part of the core layer, and concentrating and irradiating a laser beam into the core layer to modify a part of the core layer. Since each linear region of the grating can be formed by improving the quality of the grating, the grating can be formed by a simple process without using a relatively complicated process such as a lithography method, and the optical coupler can be formed. Occasionally, damage to the surface of the core layer can be prevented.

According to the invention of claim 8, in the invention of claim 7, in order to form each of the linear regions, the laser light is focused and irradiated in a spot-like manner in the core layer, so that each line is scanned. The cross section orthogonal to the extension direction of the linear region can be formed in a circular shape, and moreover, the linear regions can be easily formed whether they are linear or curved.

According to a ninth aspect of the present invention, in order to form each of the linear regions, the laser light is focused and irradiated in a plurality of spots in the core layer to scan, and Since a plurality of linear regions can be formed by one scan, the manufacturing time can be shortened and the cost can be reduced as a result.

According to a tenth aspect of the invention, in the invention of the seventh aspect, in order to form each of the linear regions, the laser light is condensed into a linear shape corresponding to the shape of each of the linear regions. Since the irradiation is performed, the manufacturing time can be significantly shortened as compared with the case where the laser light is focused and scanned in a dot shape.

According to the invention of claim 11, in the invention of claim 8 or claim 9, the scanning direction of the laser beam is aligned with the extension direction of each of the linear regions, so that each of the linear regions has various shapes. It becomes possible to correspond to the shape.

A twelfth aspect of the present invention is the method for manufacturing an optical coupler according to the fourth or fifth aspect, wherein when forming the plurality of gratings, laser light is focused and irradiated into the core layer. When repeating the process of forming the grating by modifying a part of the core layer,
The position for converging and irradiating the laser beam in the thickness direction of the core layer is adjusted, and a grating corresponding to the multimode optical waveguide can be easily formed.

According to a thirteenth aspect of the present invention, in the method of manufacturing the optical coupler according to the fifth aspect, in forming the plurality of gratings, laser light is condensed and irradiated into the core layer to form the core layer. When repeating the process of forming the grating by modifying a part thereof, the position of the core layer in the light propagation direction is shifted and the position of concentrating and irradiating the laser light in the thickness direction of the core layer is adjusted. The grating corresponding to the multi-mode optical waveguide can be easily formed.

According to a fourteenth aspect of the present invention, in the method of manufacturing the optical coupler according to the sixth aspect, in forming the grating, a laser beam is condensed and irradiated into the core layer to partially expose the core layer. When repeating the process of forming the linear region by modifying the, the position to focus and irradiate the laser light in the thickness direction of the core layer is adjusted, in the thickness direction of the core layer. It is possible to easily form a grating in which the formation position of the linear region gradually changes along the light traveling direction.

A fifteenth aspect of the present invention is the method for manufacturing an optical coupler according to the sixth aspect, wherein the core layer is condensed and irradiated with laser light to modify a part of the core layer. The laser light is formed in a state where the linear region is formed, the thickness direction of the core layer is aligned with the normal direction of the virtual horizontal plane, and the optical axis of the laser light is inclined with respect to the thickness direction of the core layer. It is possible to easily form a grating in which the formation position of the linear region in the thickness direction of the core layer gradually changes along the traveling direction of the light.

According to a sixteenth aspect of the present invention, in the method of manufacturing the optical coupler according to the sixth aspect, laser light is focused and irradiated into the core layer to modify a part of the core layer. The laser light in the state where the linear region is formed, the thickness direction of the core layer is inclined from the normal direction of the virtual horizontal plane, and the optical axis direction of the laser light is aligned with the normal direction of the virtual horizontal plane. It is possible to easily form a grating in which the formation position of the linear region in the thickness direction of the core layer gradually changes along the traveling direction of the light.

According to a seventeenth aspect of the present invention, a circuit board, an optical device mounted on the circuit board, and a core disposed so as to cover at least the optical device on a surface side of the circuit board on which the optical device is mounted. The optical waveguide according to any one of claims 1 to 3, wherein an optical waveguide whose layer thickness direction matches the thickness direction of the circuit board, and which couples light between the optical waveguide and the optical device. Since the optical coupler is composed of a grating, it is not necessary to use a reflector plate machined with high precision, which facilitates miniaturization and cost reduction. ,
Since the grating is formed in the core layer, the interaction with the guided light can be enhanced and the coupling efficiency can be improved compared to the case where the grating formed at the interface between the core and the clad as in the past is used. Can be increased.

The invention of claim 18 is the method of manufacturing an opto-electric hybrid wiring board according to claim 17, wherein the optical waveguide is formed after the optical device is mounted on the circuit board,
After that, after determining the formation position of the optical coupler in the core layer, a laser beam is condensed and irradiated in the core layer to modify a part of the core layer to form the optical coupler. An alignment mark provided near the optical device on the circuit board when forming the linear regions of the constituent gratings and determining the formation position of the optical coupler, the optical device itself, and the optical device. The formation position of the optical coupler is determined by recognizing any one of the alignment marks provided above, and the optical device is mounted on the circuit board to further form the optical waveguide. Since the optical coupler can be formed after that, it is possible to easily form an opto-electric hybrid wiring board that can be reduced in cost and downsized, and is also easy to produce a wide variety of products. It is possible to cope with.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) An opto-electric hybrid wiring board according to this embodiment has an insulating substrate 1 as shown in FIG.
The light receiving element 2 which is an optical device for converting an optical signal into an electric signal is mounted on the circuit board 1 which is a printed board having the conductor pattern 1b formed on one surface of the circuit board 1.
The plate-shaped optical waveguide 3 is formed on one surface side of the optical waveguide 3.
A reflective layer 4 made of a metal material is formed on the top.

The light receiving element 2 is a surface light receiving type pin photodiode chip in which a light receiving portion 2a is formed on the main surface side, and electrodes (not shown) are provided on the main surface and the back surface, respectively.
Is formed, the electrode on the back surface is bonded to the conductor pattern 1b of the circuit board 1 using a conductive resin and electrically connected to the conductor pattern 1b, and the electrode on the main surface is formed on the other side of the circuit board 1. It is electrically connected to the conductor pattern 1b through a gold wire W.

The optical waveguide 3 is composed of a core layer 3b for transmitting an optical signal, and clad layers 3a and 3c formed on both sides of the core layer 3b in the thickness direction (vertical direction in FIG. 1). One clad layer (hereinafter referred to as a first clad layer) 3a is formed so as to cover the light receiving element 2, the gold wire 6 and the like on the one surface side of the circuit board 1, and the core layer 3b is formed on the first clad layer 3a. And the other clad layer (hereinafter referred to as the second clad layer) 3c is formed on the core layer 3b. In the core layer 3b, a grating 7 is formed above the light receiving element 2 as an optical coupler for emitting (radiating) the light propagating through the core layer 3b to the light receiving portion 2a of the light receiving element 2. Here, as shown in FIG. 1B, the grating 7 is formed in an area wider than the area corresponding to the light receiving portion 2a of the light receiving element 2 in the thickness direction of the circuit board 1.

In the optical waveguide 3, the light having a wavelength of 850 nm is set as the light propagating in the core layer 3b.
Has a refractive index of 1.31 and each of the cladding layers 3a and 3c has a refractive index of 1.29, and the guided mode of the propagating light is only the 0th mode (fundamental mode) (that is, a single mode optical waveguide). ), The thickness of the core layer 3b is set to 1.86 μm.
Is set to.

Core layer 3b and clad layers 3a and 3c
Are each made of an optical polymer material, and the first cladding layer 3a is formed by a so-called casting method as described later. Here, in the present embodiment, the thickness of the first cladding layer 3a reduces the unevenness caused by the light receiving element 2 or the like, which is a mounting component on the one surface side of the circuit board 1, and the surface of the first cladding layer 3a is The thickness is set so as to be flat, and the generation of irregularities at the interface between the first cladding layer 3a and the core layer 3b is suppressed. That is, the first cladding layer 3a has a function of smoothing the unevenness on the one surface side of the circuit board 1.

The above-mentioned grating 7 provided in the core layer 3b is provided in the light receiving element 2 in the thickness direction of the circuit board 1.
Is formed in a portion overlapping the light receiving portion 2a. Therefore, the 0th-order mode guided light (optical signal) 9a propagating through the core layer 3b is reflected upward and downward by the grating 7, and is reflected downward by the grating 7 (combined spatial light). ) 9b is incident on the light receiving element 2 together with the light reflected upward by the grating 7 and reflected downward by the reflective layer 4,
Is converted from an optical signal to an electrical signal.

By the way, the grating 7 is composed of the core layer 3
It is formed at the center of b in the thickness direction. Here, the thickness direction of the core layer 3b is a direction along a direction orthogonal to the light propagation direction (the optical axis direction of the core layer 3b),
When the z axis is taken in the optical axis direction of the core layer 3b, the y axis is taken in the thickness direction of the core layer 3b, and the x axis is taken in the direction orthogonal to the z axis and the y axis, the grating 7 is formed along the x axis direction. Many of them (only 9 shown in Fig. 1
40 fine line-shaped linear regions 7a have a pitch of about the wavelength of the propagating light (a value of about ½ to one wavelength of the wavelength of the propagating light, specifically, [wavelength in free space]). ÷ [Effective refractive index of core layer] needs to be appropriately set by designing the waveguide mode and the entrance / exit angle based on the value obtained as a standard. In the present embodiment, it is set to 0.7 μm)
It has a one-dimensional periodic structure regularly arranged in the axial direction, and is formed in a stripe shape as a whole. Each linear region 7a is selectively formed in the core layer 3b by modifying a part of the core layer 3b, has a polymer structure different from that of the surrounding region, and has a refractive index of several% (in the present embodiment. 2%). That is, each linear region 7a has a different refractive index from the core layer 3b. Each linear region 7a has a circular cross-sectional shape orthogonal to the extending direction (in the present embodiment, the x-axis direction), and has a diameter of about half the pitch (0.35μ in the present embodiment).
m) is set.

The electric field distribution of the guided light 9a of the 0th mode in the core layer 3b is shown in the inset diagram surrounded by the one-dot chain line A in FIG. This inset shows the intensity distribution of the electric field of the guided light 9a when the thickness of the core layer 3b is 2a and the position at the center of the core layer 3b in the y-axis direction is y = 0. . That is, the amplitude of the electric field of the guided light 9a of the 0th-order mode is maximum at the center with the optical axis of the core layer 3b as the center and becomes lower as the distance from the optical axis increases, but in the present embodiment, the grating 7 is arranged in the thickness direction of the core layer 3b. Since it is formed in the center of, the formation position of the grating 7 coincides with the position where the electric field amplitude of the guided light 9a of the 0th-order mode becomes maximum, and high coupling efficiency can be obtained. The inset surrounded by the one-dot chain line B in FIG. 1 is a diagram showing the intensity distribution of the spatially radiated light 9b traveling from the grating 7 to the light receiving element 2, and the intensity of the spatially radiated light 9b is the propagation direction of the optical signal. It is designed to exponentially decay along the (z-axis direction).

A method of manufacturing the above-mentioned opto-electric hybrid wiring board will be described below with reference to FIG.

First, by mounting the light receiving element 2 on the one surface side of the circuit board 1, the structure shown in FIG. 2A is obtained.

Thereafter, the first surface is provided on the one surface side of the circuit board 1.
The structure shown in FIG. 2B is obtained by forming the clad layer 3a by, for example, the casting method. The thickness of the first cladding 3a is such that the unevenness caused by the light receiving element 2 or the like, which is the mounting component on the one surface side of the circuit board 1, is alleviated and the surface of the first cladding layer 3a becomes flat. Is set to.

Subsequently, a film (optical wiring layer film) in which the core layer 3b and the second clad layer 3c are laminated is laminated on the first clad layer 3a and then cured to form the first clad layer 3a. The optical waveguide 3 is formed by completely adhering it to the core layer 3b, and the structure shown in FIG. 2C is obtained.

Next, after recognizing the light receiving portion 2a of the light receiving element 2 from above the core layer 3b, as shown in FIG.
The pulsed laser light 16 is applied from above the core layer 3b to the core layer 3b.
By concentrating and irradiating each of the linear regions 7a in which the linear regions 7a are to be formed, a part of the core layer 3b is selectively modified to form the grating 7 including a large number of linear regions 7a. Here, the pulsed laser light 16 is focused by the cylindrical lens 17 into a single linear shape and is irradiated onto the area where the linear area 7a is to be formed in the core layer 3b. The light source for outputting the pulsed laser light 16 has a wavelength of 80
A light source having a wavelength of 0 nm, a pulse width of 150 fs, a pulse repetition frequency of 1 kHz, and an average output of 20 μW is used.

After the grating 7 is formed, the reflective layer 4 made of a metallic material is formed on the second cladding layer 3c to obtain the structure shown in FIG. 2E (that is, FIG. 1A). .

In the manufacturing method described above, when the grating 7 is formed, the process of linearly converging the pulsed laser light 16 by the cylindrical lens 17 and irradiating it is shifted in the z-axis direction by the pitch. While repeating, for example, pulsed laser light 1
The process of condensing 6 in a point shape by a condensing lens and scanning along the above-mentioned x-axis direction may be repeated while being shifted by the above pitch, or the condensing lens and the diffraction grating or the beam splitter may be replaced. They may be combined and formed as one line of point groups or straight line groups.

Further, in the above-mentioned manufacturing method, the film composed of the core layer 3b and the second clad layer 3c is laminated on the first clad layer 3a, but the film composed of the core layer 3b is laminated on the first clad layer 3a. It may be laminated or the core layer 3b may be formed by a casting method. Further, in the above manufacturing method,
It may be possible that the core layer 3b is deformed due to the inclusion of dust or the like at the interface between the first clad layer 3a and the core layer 3b. Therefore, for example, clad layers are provided in advance on both sides in the thickness direction of the core layer 3b. Film the first clad layer 3
It may be laminated on a.

In the opto-electric hybrid wiring board according to this embodiment, however, a grating formed in the core layer 3b as an optical coupler for emitting the light propagating through the core layer 3b of the optical waveguide 3 to the light receiving element 2. 7 is provided, it is not necessary to use a highly accurately machined reflection plate, and when it is used as an opto-electric hybrid wiring board, positioning with respect to the optical waveguide is not required and cost can be reduced. Since it is formed in the core layer 3b, the interaction with the guided light can be enhanced and the coupling efficiency can be enhanced as compared with the conventional grating formed at the interface between the core and the clad. Further, since each linear region 7a forming the grating 7 is provided within the thickness dimension of the core layer 3b (that is, the wire diameter of each linear region 7a is sufficiently smaller than the thickness dimension of the core layer 3b). Layer 3b
Can meet the phase matching condition in the thickness direction of
Only by adjusting the period of the linear region 7a in the grating 7, coupling with an optical device in any direction becomes possible.

In this embodiment, the grating 7
Although a large number of linear regions 7a constituting the above are arranged at regular intervals, the period of the linear regions 7a may be continuously changed (chirped).

(Embodiment 2) The basic structure of the opto-electric hybrid wiring board of this embodiment shown in FIG. 3 is substantially the same as that of Embodiment 1, except for the optical coupler and the waveguide mode of the core layer 3b. The same as 1. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the optical waveguide 3 in this embodiment, light having a wavelength of 850 nm is set as the light propagating in the core layer 3b, the core layer 3b has a refractive index of 1.31, and the cladding layers 3a and 3c have a refractive index of 1.31. The ratio is 1.29, and the guided modes of propagating light are the 0th-order mode and the 1st-order mode (that is,
The thickness of the core layer 3b is set to 3.7 μm so as to form a multimode optical waveguide.

Further, in this embodiment, the core layer 3b is formed by the two gratings 7 and 8 formed in the core layer 3b.
An optical coupler that emits (emits) the light propagating through the light receiving element 2 is configured. Here, the grating 7 is
Like the first embodiment, it is provided to radiate the 0th-order mode guided light 9a to the outside of the optical waveguide 3 (to enter the light receiving element 2), and is formed in the center of the core layer 3b in the thickness direction. Has been done. That is, the grating 7
In the same manner as in the first embodiment, a large number of lines are formed along the x-axis direction (only nine lines are shown in FIG.
The linear region 7a of the present) has a pitch of about the wavelength of the propagating light (a value around ½ to one wavelength of the propagating light, specifically, [wavelength in free space] ÷ [effectiveness of core layer] Refractive index] needs to be set as appropriate by designing the waveguide mode and the entrance / exit angle, and is set to 0.8 μm in the present embodiment). It has a dimensional periodic structure and is formed in a stripe shape as a whole. Each linear region 7a is formed by modifying a part of the core layer 3b as in the first embodiment.
It is selectively formed in b and has a polymer structure different from that of the surrounding region and a refractive index of several% (in the present embodiment, 2
%) Higher. That is, each linear region 7a has a different refractive index from the core layer 3b. Each linear region 7a has a circular cross-sectional shape orthogonal to the extending direction (in the present embodiment, the x-axis direction), and has a diameter (wire diameter) of about half the above-described pitch (in the present embodiment, in the present embodiment). , 0.45μ
m) is set.

Similarly, in the grating 8 as well, a large number of linear regions 8a (although only nine are shown in FIG. 3, although 70 are shown in FIG. 3) formed along the x-axis direction are about the wavelength of the propagating light. Pitch (value around ½ to one wavelength of the propagation light, specifically, [wavelength in free space] ÷
It is necessary to properly set the value obtained by the [effective refractive index of the core layer] as a guide by designing the waveguide mode and the entrance / exit angle. In the present embodiment, it is set to 0.8 μm) in the z-axis direction. It has a one-dimensional periodic structure arranged in, and is formed in a stripe shape as a whole. Each linear area 8
a is the core layer 3 by modifying a part of the core layer 3b.
It is selectively formed in b and has a polymer structure different from that of the surrounding region and a refractive index of several% (in the present embodiment, 2
%) Higher. That is, each linear region 8a has a different refractive index from the core layer 3b. Each linear region 8a has a circular cross-sectional shape orthogonal to the extension direction (x-axis direction), and has a diameter (wire diameter) of about half the pitch (0.45 μm in the present embodiment). Is set to. However, the grating 8 is provided to radiate the guided light 9c of the primary mode to the outside of the optical waveguide 3 (to enter the light receiving element 2), and the formation position in the thickness direction of the core layer 3b is Different from Grating 7. The formation position of the grating 8 in the thickness direction of the core layer 3b (the y-axis direction) is set to a position where the electric field amplitude of the guided light 9c in the primary mode is maximum (maximum electric field amplitude position). The intensity distributions of the electric fields of the guided lights 9a and 9c in the core layer 3b are shown in the insets surrounded by the constant chain lines A1 and A2 in FIG. 3, respectively. These insets show the electric field distribution of the guided light beams 9a and 9c when the thickness of the core layer 3b is 2a and the position at the center of the core layer 3b in the y-axis direction is y = 0.

Therefore, also for the grating 8, high coupling efficiency can be realized as in the case of the grating 7. That is, since the formation positions of the gratings 7 and 8 coincide with the maximum electric field amplitude positions of the guided light beams 9a and 9c that interact with each other, high coupling efficiencies can be obtained. An optical coupler having high coupling efficiency can be obtained even when 3 is a multimode optical waveguide.

The two gratings 7 and 8 are arranged on the left side of the center of the light receiving portion 2a of the light receiving element 2 in the traveling direction of the propagating light (that is, the optical axis direction of the core layer 3b). A grating 8 is arranged on the right side of the center, and guided light 9a of the 0th mode is radiated slightly obliquely forward with respect to the traveling direction by the grating 7 and enters the light receiving portion 2a as spatial radiated light 9b.
The guided light 9c of the first-order mode is radiated by the grating 8 slightly obliquely backward with respect to the traveling direction, and the spatial radiated light 9c
It is incident on the light receiving portion 2a as d. The insets surrounded by the one-dot chain lines B1 and B2 in FIG.
Radiation 9b from the light receiving section 2a of the light receiving element 2 to
The intensity distribution of 9d is shown.

The manufacturing method of this embodiment is substantially the same as that of the first embodiment, but the forming process of the optical coupler is different. That is, in this embodiment, after laminating the film including the core layer 3b and the second clad layer 3c on the first clad layer 3a as in the first embodiment, as shown in FIG. Pulsed laser light 16 from the core layer 3
The gratings 7 and 8 are formed by converging and irradiating the light in the area b.
Here, the laser device that outputs the pulsed laser light 16 is the same as that described in the first embodiment, and the pulsed laser light 16 is divided by the beam splitter 18 and a plurality of laser beams 16a arranged in one row at equal intervals. After
Each laser beam 1 by the cylindrical lens 17a
Each of 6a is linearly condensed and irradiated into the core layer 3b. In the manufacturing method of this embodiment, when forming the optical coupler, first, the circuit board 1 is placed on a stage (not shown) whose height is adjustable, and then the laser beam 16a forms the linear region 7a. After adjusting the height of the stage so that the laser beam 16a is focused on a predetermined region, the laser beam 16a is focused and irradiated on the core layer 3b to form the grating 7. Then, the laser beam 16a is focused on the linear region 8a. The height of the stage is changed so that the laser beam 16a is focused on the core layer 3b so that the grating 8 is formed, after the height of the stage is changed so that the grating 8 is focused on the area to be formed.

As a method of forming the gratings 7 and 8 by the pulsed laser beam 16, it is needless to say that the same method as the method of forming the grating described in the first embodiment may be adopted.

(Embodiment 3) The basic structure of the opto-electric hybrid wiring board of this embodiment is substantially the same as that of Embodiment 1, but the structure of the grating 7 is different as shown in FIG. In addition,
The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The grating 7 in this embodiment is formed so as to be inclined with respect to the interface between the core layer 3b and the first cladding 3a. That is, in the grating 7, the formation position of the linear region 7a in the thickness direction of the core layer 3b is changed along the traveling direction of the propagating light (z-axis direction). The grating 7 has the same structure as that of the first embodiment.
It has 0 linear regions 7a, and the diameter (line diameter) of the cross section orthogonal to the extension direction (x-axis direction) of each linear region 7a is set to 0.35 μm.

The manufacturing method of this embodiment is substantially the same as that of the first embodiment, but the steps of forming the optical coupler are different. That is, in the present embodiment, as in the first embodiment, after laminating the film including the core layer 3b and the second clad layer 3c on the first clad layer 3a, the pulsed laser light 16 is applied to the core as shown in FIG. The grating 7 is formed by converging and irradiating in the layer 3b. Here, the laser device that outputs the pulsed laser light 16 is the same as that described in the first embodiment, and the pulsed laser light 16 is divided by the beam splitter 18 and a plurality of laser beams 16a arranged in one row at equal intervals. After that, each laser beam 16a is focused and scanned in the core layer 3b by the cylindrical lens 17a. However, in this embodiment,
After mounting the circuit board 1 on a tiltable stage (not shown), the stage is tilted from a virtual horizontal plane (not shown) according to the tilt angle between the core layer 3b and the cladding layer 3a, and then the laser beam 16a Is focused and irradiated to form the grating 7. Therefore, it is possible to collectively form each of the linear regions 7a forming the grating 7 described above.

The grating 7 in this embodiment is
The formation positions of the linear regions 7a in the thickness direction of the core layer 3b are made different along the traveling direction of the propagating light (that is,
Since the formation position of the linear region 7a is depth-modulated,
The coupling efficiency with the guided light 9a also changes along the traveling direction of the propagating light, and the spatial emission light 9b having the intensity distribution as shown in the inset diagram surrounded by the alternate long and short dash line B in FIG.
Is emitted to. Here, in the first embodiment, the intensity distribution of the spatially radiated light 9b is attenuated exponentially along the propagation direction (z-axis direction) of the optical signal as shown in the inset surrounded by the alternate long and short dash line B in FIG. However, in this embodiment, the intensity distribution of the spatially radiated light 9b is closer to the intensity distribution of the guided light 9a.

In this embodiment, the grating 7
Constructs an optical coupler that emits the guided light 9a to the light receiving element 2. However, due to the reciprocity of electromagnetic waves (reciprocity theorem), for example, a surface emitting laser diode (Vertical-Cavity) that extracts light in the vertical direction of the active layer -Surface-Emitting Laser dio
It can be seen that the incident light from the optical device such as de) can be efficiently coupled to the guided light of the optical waveguide 3.

As for the method of forming the grating 7 by the pulsed laser beam 16, the core layer 3b is focused and irradiated in the same manner as in the first embodiment with the stage tilted as described above. You can
The core layer 3b is the same as in the first embodiment without tilting the stage.
It may be formed by condensing and irradiating the light inside, or the pulsed laser light 16 may be condensed by a condensing lens.
The process of condensing and irradiating spots in b and scanning in a straight line may be repeated while changing the formation position (depth) in the thickness direction of the core layer 3b. Further, in the present embodiment, the grating 7 is formed collectively by the inclination of the stage, but the optical axis of the optical system for irradiating the pulsed laser light 16 may be formed so as to be inclined with respect to the normal direction of the virtual horizontal plane. You may

(Embodiment 4) The basic structure of the opto-electric hybrid wiring board of this embodiment is for coupling the guided light of the optical waveguide 3 to the light emitted to the light receiving element 2 as described in the first to third embodiments. Instead of the optical coupler, as shown in FIG. 7A, a light emitting element 12 formed of a surface emitting diode is mounted on the circuit board 1 instead of the light receiving element 2 as an optical device.
The light emitting element 12 is characterized in that it has a grating 7 as an optical coupler for coupling the emitted light 9e from the light emitting portion 12a with the guided light 9f. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, each linear region 7a of the grating 7 is formed in a curved shape as shown in FIG. 7B, and the guided light which does not diverge in the light propagation direction of the core layer 3b. Can be excited. Further, the linear region 7a of the grating 7 in the present embodiment is similar to the third embodiment in the linear region 7 in the thickness direction of the core layer 3b.
Since the formation position of a is made different along the traveling direction of the propagating light (that is, the formation position of the linear region 7a is depth-modulated), it is different from the guided light 9f along the traveling direction of the propagating light. The coupling efficiency also changes, and the spatially radiated light 9b having the intensity distribution as shown in the inset surrounded by the alternate long and short dash line C in FIG. 7A is incident on the core layer 3b. Here, in this embodiment,
The intensity distribution of the guided light 9f as shown in the inset in FIG. 7A surrounded by the alternate long and short dash line D is closer to the intensity distribution of the spatially radiated light 9e. .

The method of manufacturing the opto-electric hybrid wiring board of this embodiment is the same as that of the third embodiment, and the light emitting element 12 is mounted on the circuit board 1 and the first clad layer 3a is formed. By laminating a film composed of the core layer 3b and the second cladding layer 3c on the first cladding layer 3a, the pulsed laser light is focused and irradiated into the core layer 3b to modify a part of the core layer 3b. The grating 7 is formed. However, in the manufacturing method of the present embodiment, a plurality of laser beams 16a are focused and irradiated in the core layer 3b in a spot shape, and the grating 7 is scanned by curving along the area where the linear area 7a is to be formed. Is forming.

Regarding the forming method for forming the grating 7 by the pulsed laser beam 16, a process of converging and irradiating the core layer 3b in a spot-like manner with a condenser lens without inclining the stage and scanning it in a curved manner is described. It may be repeated while changing the formation position (depth) in the thickness direction of the core layer 3b. Further, in the present embodiment, the grating 7 is formed collectively by the inclination of the stage, but the optical axis of the optical system for irradiating the pulsed laser light 16 may be formed so as to be inclined with respect to the normal direction of the virtual horizontal plane. You may Further, although a large number of linear regions 7a forming the grating 7 are arranged at regular intervals, the period of the linear regions 7a may be continuously changed (chirped).

By the way, in each of the above-described embodiments, the optical coupler (the grating 7 in the first, third, and fourth embodiments, and the grating 7, 8 in the second embodiment) is provided in advance in the light receiving portion 2a of the light emitting element 2 or the light emitting element 12. After recognizing and grasping the light emitting unit 12a, the entire light receiving unit 2a or the light emitting unit 1
Although it is formed so as to cover the entire area of 2a, it is formed on an alignment mark provided in the vicinity of the optical device (light receiving element 2 to light emitting element 12) mounted on the circuit board 1, or on the optical device itself or on the optical device. The formed alignment mark may be recognized to determine the formation position of the optical coupler.

The optical coupler in each of the above embodiments is used to couple light between the optical waveguide 3 and the optical device. However, the optical coupler is used to couple light between the optical waveguide 3 and other optical waveguides. It may be used for binding. Further, in each of the above-described embodiments, the refractive index of the linear regions 7a and 8a of the gratings 7 and 8 is higher than the refractive index of the core layer 3b, but the refractive index of the linear regions 7a and 8a is the core layer 3b. The refractive index of the linear regions 7a and 8a may be smaller than that of the core layer 3b.

[0065]

According to the first aspect of the present invention, there is provided an optical coupler for coupling light between an optical waveguide and another optical waveguide or an optical device, which has a large number of different refractive indexes from the core layer of the optical waveguide. The fine linear region is provided with at least one grating regularly arranged in the core layer at intervals of about the wavelength of light guided in the core layer, and the linear region is such that each linear region is within the thickness dimension of the core layer. Since it is provided, and since the optical coupler is composed of a grating, it is not necessary to use a reflector plate machined with high precision, and positioning with respect to the optical waveguide is unnecessary when using it for an opto-electric hybrid wiring board. Therefore, the cost can be reduced, and since the grating is formed in the core layer, it interacts with the guided light as compared to the conventional grating formed at the interface between the core and the clad. It has the effect of increasing the coupling efficiency, and since each linear region forming the grating is provided within the thickness dimension of the core layer, the phase matching condition in the thickness direction of the core layer can be set. There is an effect that it can be satisfied, and coupling with an optical device in any direction becomes possible only by adjusting the period of the linear region in the grating.

According to a second aspect of the present invention, there is provided an optical coupler for coupling light between an optical waveguide and another optical waveguide, wherein a large number of fine linear regions having a different refractive index from the core layer of the optical waveguide. Has at least one grating regularly arranged in the core layer at intervals of about the wavelength of light guided in the core layer, and the grating has each linear region provided within the thickness dimension of the core layer. Since the optical coupler is composed of a grating, it is not necessary to use a highly-precision machined reflector, and when using it for an opto-electric hybrid wiring board, positioning is not required for the optical waveguide and cost reduction is achieved. Moreover, since the grating is formed in the core layer, it is possible to enhance the interaction with the guided light as compared with the conventional grating formed at the interface between the core and the clad. There is an effect that it is possible to increase the coupling efficiency, and since each linear region constituting the grating is provided within the thickness dimension of the core layer, can satisfying the phase matching condition in the thickness direction of the core layer,
There is an effect that coupling with an optical device in an arbitrary direction becomes possible only by adjusting the period of the linear region in the grating.

According to a third aspect of the present invention, in the first or second aspect of the invention, the grating is a waveguide that propagates the formation position of each of the linear regions in the core layer in the thickness direction of the core layer. Since it is matched with the position where the amplitude of the electric field of the mode light is maximized, there is an effect that the coupling efficiency in the optical coupler can be increased.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the optical waveguide is a multimode optical waveguide having a plurality of waveguide modes, and the grating is provided in the number of waveguide modes. Are formed at positions where the amplitude of the electric field of light in each of the guided modes is maximized in the thickness direction of the core layer, so that the coupling efficiency of the optical coupler with respect to the multimode optical waveguide can be improved. The effect is that you can do it.

According to the invention of claim 5, in the invention of claim 4, since the respective gratings are arranged along the light propagation direction of the core layer, even if the thickness of the core layer is thin, There is an effect that it is possible to prevent the gratings corresponding to each wave mode from overlapping or interfering with each other.

According to a sixth aspect of the present invention, in the first or second aspect of the invention, the grating defines the position where each of the linear regions is formed in the thickness direction of the core layer along the light propagation direction of the core layer. Since the intensity of the interaction with the light wave changes depending on the position along the light propagation direction, for example, when the guided light of the optical waveguide is emitted to the outside of the optical waveguide. Has the effect that the shape of the intensity distribution of spatially radiated light (light incident on an optical device or other optical waveguide) can be approximated to the shape of the intensity distribution of guided light of an optical waveguide. When the light emitted from the optical waveguide is incident on the optical waveguide, the shape of the intensity distribution of the guided light can be approximated to the shape of the intensity distribution of the spatial light, and the coupling efficiency can be improved. There is a result.

A seventh aspect of the present invention is the method for manufacturing an optical coupler according to any one of the first to sixth aspects, wherein laser light is introduced into the core layer when the grating is formed. Since each linear region is formed by converging and irradiating to modify a part of the core layer, converging and irradiating laser light into the core layer to modify a part of the core layer. Since each of the linear regions of the grating can be formed by, there is an effect that the grating can be formed by a simple process without using a relatively complicated process such as a lithography method. This has the effect of preventing damage to the surface of the core layer during formation.

According to the invention of claim 8, in the invention of claim 7, in order to form each of the linear regions, the laser light is focused and irradiated in spots in the core layer, so that each line is scanned. It is possible to form a circular cross section orthogonal to the extension direction of the linear region, and it is possible to easily form the linear region regardless of whether the linear region is linear or curved. effective.

According to the invention of claim 9, in the invention of claim 7, in order to form each of the linear regions, the laser light is condensed and irradiated in a plurality of spots in the core layer, and scanning is performed. Since a plurality of linear regions can be formed by one scanning, the manufacturing time can be shortened, and as a result, the cost can be reduced.

According to a tenth aspect of the invention, in the invention of the seventh aspect, in order to form the linear regions, the laser light is condensed into a linear shape corresponding to the shape of the linear regions in the core layer. Since the irradiation is performed, there is an effect that the manufacturing time can be significantly shortened as compared with the case where the laser light is condensed in a spot shape and scanned.

According to the invention of claim 11, in the invention of claim 8 or claim 9, since the scanning direction of the laser beam is aligned with the extension direction of each of the linear regions, various shapes of the linear regions can be obtained. The effect is that it can be adapted to the shape.

According to a twelfth aspect of the present invention, there is provided a method for manufacturing an optical coupler according to the fourth or fifth aspect, wherein the core layer is condensed and irradiated with laser light when the plurality of gratings are formed. When repeating the process of forming the grating by modifying a part of the core layer,
Since the position where the laser light is focused and irradiated is adjusted in the thickness direction of the core layer, there is an effect that a grating corresponding to the multimode optical waveguide can be easily formed.

According to a thirteenth aspect of the present invention, in the method of manufacturing the optical coupler according to the fifth aspect, in forming the plurality of gratings, a laser beam is condensed and irradiated into the core layer to form the core layer. When repeating the process of forming the grating by modifying a part thereof, the position of the core layer in the light propagation direction is shifted and the position of concentrating and irradiating the laser light in the thickness direction of the core layer is adjusted. Therefore, there is an effect that a grating corresponding to the multimode optical waveguide can be easily formed.

According to a fourteenth aspect of the present invention, in the method of manufacturing the optical coupler according to the sixth aspect, in forming the grating, a laser beam is focused and irradiated into the core layer to form a part of the core layer. When repeating the process of forming the linear region by modifying, the position for converging and irradiating the laser beam in the thickness direction of the core layer is adjusted, so that the linear shape in the thickness direction of the core layer is adjusted. There is an effect that it is possible to easily form a grating in which the formation position of the region gradually changes along the light traveling direction.

According to a fifteenth aspect of the present invention, in the method of manufacturing the optical coupler according to the sixth aspect, laser light is focused and irradiated into the core layer to modify a part of the core layer. The laser light is formed in a state where the linear region is formed, the thickness direction of the core layer is aligned with the normal direction of the virtual horizontal plane, and the optical axis of the laser light is inclined with respect to the thickness direction of the core layer. Since the scanning is performed, it is possible to easily form a grating in which the formation position of the linear region in the thickness direction of the core layer is gradually changed along the light traveling direction.

According to a sixteenth aspect of the present invention, in the method of manufacturing an optical coupler according to the sixth aspect, laser light is focused and irradiated into the core layer to modify a part of the core layer. The laser light in the state where the linear region is formed, the thickness direction of the core layer is inclined from the normal direction of the virtual horizontal plane, and the optical axis direction of the laser light is aligned with the normal direction of the virtual horizontal plane. Since the scanning is performed, it is possible to easily form a grating in which the formation position of the linear region in the thickness direction of the core layer is gradually changed along the light traveling direction.

According to a seventeenth aspect of the present invention, there is provided a circuit board, an optical device mounted on the circuit board, and a core disposed so as to cover at least the optical device on a surface side of the circuit board on which the optical device is mounted. The optical waveguide according to any one of claims 1 to 3, wherein an optical waveguide whose layer thickness direction matches the thickness direction of the circuit board, and which couples light between the optical waveguide and the optical device. Since the optical coupler is composed of a grating, there is no need to use a reflector plate machined with high precision, and there is an effect that miniaturization and cost reduction can be facilitated.
Since the grating is formed in the core layer, the interaction with the guided light can be enhanced and the coupling efficiency can be improved compared to the case where the grating formed at the interface between the core and the clad as in the past is used. There is an effect that can increase.

The invention of claim 18 is the method of manufacturing an opto-electric hybrid wiring board according to claim 17, wherein the optical waveguide is formed after the optical device is mounted on the circuit board,
After that, after determining the formation position of the optical coupler in the core layer, a laser beam is condensed and irradiated in the core layer to modify a part of the core layer to form the optical coupler. An alignment mark provided near the optical device on the circuit board when forming the linear regions of the constituent gratings and determining the formation position of the optical coupler, the optical device itself, and the optical device. Since the formation position of the optical coupler is determined by recognizing any one of the alignment marks provided above, after the optical device is mounted on the circuit board and the optical waveguide is further formed. Since the optical coupler can be formed, it is possible to easily form an opto-electric hybrid wiring board that can be manufactured at low cost and can be downsized, and easily handle multi-product production. There is an effect that theft can be.

[Brief description of drawings]

1A and 1B show a first embodiment, FIG. 1A is a schematic configuration diagram of an opto-electric hybrid wiring board, and FIG. 1B is a surface layout explanatory diagram of essential parts.

FIG. 2 is a cross-sectional view of main steps for explaining the above manufacturing method.

FIG. 3 is a schematic configuration diagram of an opto-electric hybrid wiring board showing a second embodiment.

FIG. 4 is an explanatory diagram of the above manufacturing method.

FIG. 5 is a schematic configuration diagram of an opto-electric hybrid wiring board showing a third embodiment.

FIG. 6 is an explanatory view of the above manufacturing method.

7A and 7B show a fourth embodiment, FIG. 7A is a schematic configuration diagram of an opto-electric hybrid wiring board, and FIG. 7B is an explanatory diagram of a surface layout of essential parts.

[Explanation of symbols]

1 circuit board 1a insulating substrate 1b Conductor pattern 2 Light receiving element 2a Light receiving part 3 Optical waveguide 3a clad layer 3b core layer 3c clad layer 4 Reflective layer 7 grating 7a linear area

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 1/02 H01L 31/02 D (72) Inventor Urasagi 1-14 Takakura-cho, Miyakojima-ku, Osaka No. 11 F term (reference) 2H037 AA01 BA02 BA11 CA33 2H047 KA02 LA01 MA01 PA22 QA05 TA11 5E338 AA01 BB80 DD11 EE32 EE42 5F088 BA20 BB01 HA20 JA02 JA10 JA14

Claims (18)

[Claims] 1. An optical coupler for coupling light between an optical waveguide and an optical device, wherein a large number of fine linear regions having a different refractive index from the core layer of the optical waveguide guide the core layer. An optical coupler comprising at least one grating regularly arranged in the core layer at intervals of about the wavelength of light, wherein each linear region is provided within the thickness dimension of the core layer. . 2. An optical coupler for coupling light between an optical waveguide and another optical waveguide, wherein a large number of fine linear regions having a different refractive index from the core layer of the optical waveguide guide the core layer. At least one grating is regularly arranged in the core layer at intervals of about the wavelength of the oscillating light, and the grating is
An optical coupler, wherein each linear region is provided within the thickness dimension of the core layer. 3. In the grating, the formation position of each of the linear regions is made to coincide with the position where the amplitude of the electric field of the guided mode light propagating in the core layer is maximized in the thickness direction of the core layer. The optical coupler according to claim 1 or 2, wherein 4. The optical waveguide is a multimode optical waveguide in which a plurality of guided modes exist, and the grating is provided in the number of guided modes, and each of the gratings includes:
The optical coupler according to claim 3, wherein the optical coupler is formed at a position where the amplitude of the electric field of light in each of the guided modes is maximized in the thickness direction of the core layer. 5. The optical coupler according to claim 4, wherein the gratings are arranged along the light propagation direction of the core layer. 6. The grating is formed by gradually changing a formation position of each of the linear regions in a thickness direction of the core layer along a light propagation direction of the core layer. Item 2. The optical coupler according to item 2. 7. The method for manufacturing an optical coupler according to claim 1, wherein when the grating is formed, laser light is focused and irradiated in the core layer. A method for manufacturing an optical coupler, wherein each of the linear regions is formed by modifying a part of the core layer. 8. The method of manufacturing an optical coupler according to claim 7, wherein in order to form each of the linear regions, the laser light is condensed and irradiated in a spot shape in the core layer and scanning is performed. . 9. The optical coupler according to claim 7, wherein in order to form each of the linear regions, the laser light is condensed and irradiated in a plurality of spots in the core layer to perform scanning. Production method. 10. The method according to claim 7, wherein in order to form each of the linear regions, the laser light is condensed and irradiated into the core layer in a linear shape corresponding to the shape of each of the linear regions. Optical coupler manufacturing method. 11. The method of manufacturing an optical coupler according to claim 8, wherein the scanning direction of the laser light is aligned with the extension direction of each linear region. 12. The method for manufacturing an optical coupler according to claim 4, wherein in forming the plurality of gratings, a laser beam is focused and irradiated into the core layer to form one of the core layers. A method of manufacturing an optical coupler, wherein a position for converging and irradiating the laser beam in the thickness direction of the core layer is adjusted when the process of forming the grating by modifying the portion is repeated. 13. The method of manufacturing an optical coupler according to claim 5, wherein in forming the plurality of gratings,
When repeating the process of concentrating and irradiating the core layer with laser light to modify the part of the core layer to form the grating, the position of the core layer in the light propagation direction is shifted and A method for manufacturing an optical coupler, comprising adjusting a position at which the laser light is condensed and irradiated in the thickness direction of the core layer. 14. The method for manufacturing an optical coupler according to claim 6, wherein in forming the grating, a laser beam is focused and irradiated into the core layer to modify a part of the core layer. A method for manufacturing an optical coupler, wherein the position for converging and irradiating the laser beam in the thickness direction of the core layer is adjusted when the process of forming the linear region is repeated. 15. The method for manufacturing an optical coupler according to claim 6, wherein the linear region is formed by modifying a part of the core layer by condensing and irradiating the core layer with a laser beam. And scanning the laser light in a state in which the thickness direction of the core layer is aligned with the normal direction of the virtual horizontal plane and the optical axis of the laser light is inclined with respect to the thickness direction of the core layer. A method for manufacturing a featured optical coupler. 16. The method for manufacturing an optical coupler according to claim 6, wherein the linear region is formed by condensing and irradiating a laser beam into the core layer to modify a part of the core layer. Forming the core layer and scanning the laser light in a state where the thickness direction of the core layer is inclined from the normal direction of the virtual horizontal plane and the optical axis direction of the laser light is aligned with the normal direction of the virtual horizontal plane. A method for manufacturing a featured optical coupler. 17. A circuit board, an optical device mounted on the circuit board, and a core layer having a thickness direction arranged so as to cover at least the optical device on a surface side of the circuit board on which the optical device is mounted. An optical waveguide provided in the thickness direction of the circuit board, and the optical coupler according to any one of claims 1 to 3 for coupling light between the optical waveguide and an optical device. An opto-electric hybrid wiring board characterized by. 18. The method for manufacturing an opto-electric hybrid wiring board according to claim 17, wherein the optical waveguide is formed after the optical device is mounted on the circuit board, and then the optical waveguide is formed in the core layer. After determining the formation position of the optical coupler,
A laser beam is focused and irradiated in the core layer to modify a part of the core layer so as to form each linear region of the grating forming the optical coupler, and the formation position of the optical coupler. The optical coupling by recognizing any one of the alignment mark provided in the vicinity of the optical device on the circuit board, the optical device itself, and the alignment mark provided on the optical device when determining A method for manufacturing an opto-electric hybrid wiring board, characterized in that the formation position of the container is determined.