JP2002222963A - Optical integrated circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical integrated circuit board having an enhanced photodetecting efficiency by a semiconductor photodetector for a light to be propagated through an optical waveguide. SOLUTION: The optical integrated circuit board comprises a surface photodetecting type semiconductor photodetector 2 arranged on a substrate 1, the optical waveguide having at least a lower clad part 3 and a core part 4 and formed parallel to a photodetecting surface in a light transmission direction near the element 2, and an intermediate refractive index element 6 disposed at an input side of the element 2 in a light transmission direction by the waveguide and disposed oppositely to the end face of the photodetecting surface of the element 2 and the core part 4 of the waveguide so that a refractive index is larger than that of the core part 4 and smaller than that of the photodetecting surface. Since a large refractive index change at the end face of the element 2 is alleviated, a reflection of an incident light at the end face of the photodetecting surface can be suppressed, and a propagated light of the waveguide can be efficiently optically coupled to the element 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical integrated circuit board in which an optical waveguide and a semiconductor light receiving element are integrated on the same substrate, for example, a WDM (Wavelength Division Multiplex: WDM).
It is suitably used when a plurality of semiconductor light-receiving elements and other devices are mounted on the same substrate, such as a light-receiving circuit substrate for wavelength division multiplex transmission, and the optical waveguide and the semiconductor light-receiving element are integrated on the same substrate. In addition, the present invention relates to an optical integrated circuit substrate capable of realizing a reduction in substrate size and an increase in light receiving efficiency.

[0002]

2. Description of the Related Art Conventionally, the connection between a semiconductor light receiving element and an optical waveguide in an optical integrated circuit board such as a light receiving circuit board for WDM is performed by mounting the semiconductor light receiving element above the optical waveguide layer.
In general, light from an optical waveguide is input to a light receiving section of a semiconductor light receiving element by changing an optical path through a mirror or a grating formed in the optical waveguide.

In this method, when mounting a semiconductor light receiving element, positioning for optically coupling an optical waveguide and a light receiving portion of the semiconductor light receiving element is performed by three axes in which relative positions of the semiconductor light receiving element are orthogonal to each other. It was necessary to set the direction optimally. Also, the process of manufacturing mirrors and gratings to be built in the optical waveguide is complicated.

Japanese Patent Laid-Open Publication No. Hei 7-128531 proposes a structure in which a polymer waveguide is coupled to an optical semiconductor device with high efficiency by using optical coupling. FIG.
1 shows a cross-sectional view of an example of an optical integrated circuit board proposed in Japanese Patent No. 128531. According to this, the optical waveguide is formed of a polymer waveguide, and the core portion 34 of the optical waveguide formed in the clad portion 33 is formed.
Is bent so as to ride on the upper surface of the semiconductor light receiving element composed of the semiconductor layer 35 and the light absorbing layer 32, and the gap between the end face of the semiconductor light receiving element and the core part 34 is buried with the lower clad part 33. are doing. In this structure, the electric field distribution of the propagating light is biased toward the outside of the bent portion, that is, toward the semiconductor light receiving element side at the bent portion, so that the light is easily taken into the light absorbing layer 32 of the semiconductor light receiving element, and the optical waveguide and the semiconductor light receiving element The coupling efficiency is increased.

[0005]

However, with respect to the optical integrated circuit board proposed in Japanese Patent Application Laid-Open No. Hei 7-128531, the polymer waveguide is bent so as to ride on the upper surface of the semiconductor light receiving element as shown in FIG. Therefore, when the radius of curvature of the bent portion is small, the light that has propagated through the polymer waveguide by radiating light is not coupled to the semiconductor light receiving element, and a part of the light is transmitted to the substrate or the upper cladding layer 33. There was a problem of scattering.

Also in this example, since the difference in the refractive index between the light absorbing layer 32, which is the light receiving portion of the semiconductor light receiving element, and the lower cladding 33 located at the boundary between the input side end face of the semiconductor light receiving element is large, the light There is a problem that the propagating light incident on the absorption layer 32 from the end face side is reflected on the end face of the semiconductor light receiving element perpendicular to the propagation direction of the polymer waveguide.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and it is an object of the present invention to provide an optical integrated circuit board in which the light receiving efficiency of a semiconductor light receiving element for light propagating through an optical waveguide is improved. is there.

[0008]

An optical integrated circuit substrate according to the present invention has a semiconductor light receiving element disposed on a substrate, at least a lower clad part and a core part, and has a light propagating near the semiconductor light receiving element. An optical waveguide formed so that the direction is parallel to the light receiving surface thereof, and an end face of the light receiving surface of the semiconductor light receiving element positioned on the input side of the semiconductor light receiving element in the light propagation direction by the optical waveguide and the optical waveguide. An intermediate refractive index member having a refractive index larger than that of the core portion and smaller than the light receiving surface, which is arranged to face the core portion.

[0009]

According to the optical integrated circuit substrate of the present invention, an optical waveguide is laminated on a surface light receiving type semiconductor light receiving element mounted or formed on a substrate, for example. As a result, the semiconductor light receiving element and the optical waveguide can be efficiently integrated on the same substrate, and the semiconductor light receiving element is mounted after forming the optical waveguide on the substrate as in the related art. Compared to the optical integrated circuit board, the size and height can be reduced, and further another optoelectronic device or the like can be mounted and mounted on this optical waveguide. Also for an optical integrated circuit board on which a single optical integrated circuit board is mounted, the size of the optical integrated circuit board can be reduced.

Further, according to the optical integrated circuit board of the present invention,
As the substrate, various substrates can be used as long as a substrate on which a semiconductor light receiving element can be formed or a substrate on which a semiconductor light receiving element can be mounted and mounted. More suitable substrates can be used for integration and high integration of optoelectronic devices.

Further, according to the optical integrated circuit board of the present invention,
Before the end face on the input side in the light propagation direction by the optical waveguide of the semiconductor light receiving element, facing this end face and the core part of the optical waveguide, the refractive index is larger than the core part of the optical waveguide and is higher than the light receiving surface of the semiconductor light receiving element. By arranging a small intermediate refractive index body, for the propagating light leaked from the core portion incident on the end face of the light receiving surface, a large refractive index between the light receiving surface and the clad portion at the end face of the semiconductor light receiving element, for example. Since the change is reduced, the reflection of the incident light on the end face of the light receiving surface can be suppressed, and the light propagated by the optical waveguide can be efficiently optically coupled to the semiconductor light receiving element.

Further, when the intermediate refractive index body is regarded as the second optical waveguide, light propagating through the optical waveguide is coupled to the intermediate refractive index body and output from the intermediate refractive index body due to the principle of optical coupling. The reflected light can be coupled from the end face of the semiconductor light receiving element to the light receiving portion, and the coupling efficiency can be increased as compared with the conventional relationship between the optical waveguide and the semiconductor light receiving element.

Hereinafter, an optical integrated circuit substrate according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an optical integrated circuit board showing an example of an embodiment of the optical integrated circuit board of the present invention.

As shown in FIG. 1, an optical integrated circuit board according to the present invention is formed on a surface light receiving type semiconductor light receiving element 2 provided on a substrate 1 and on the semiconductor light receiving element 2 on the substrate 1. Further, an end face of an optical waveguide composed of the lower clad part 3, the core part 4, and the upper clad part 5 and an end face of a light receiving surface located on the input side in the light propagation direction by the optical waveguide of the semiconductor light receiving element 2, usually perpendicular to the light propagation direction. The light receiving surface of the semiconductor light receiving element 2 having a refractive index larger than that of the core part 4 and disposed so as to face the end surface of the light receiving surface of the semiconductor light receiving element 2 and the lower surface of the core part 4 of the optical waveguide before the end face arranged at And an intermediate refractive index member 6 smaller than the surface. It is to be noted that the upper clad portion 5 is not always necessary, and that the upper clad portion 5 is not formed, and the upper portion of the core portion 4 is made to be air (having a refractive index of about 1). In addition, good optical connection to the semiconductor light receiving element 2 can be performed.

In the optical integrated circuit board of the present invention, the semiconductor light receiving element 2 and the intermediate refractive index body 6 are provided, and the optical waveguide is formed thereon. Various substrates used as substrates for handling optical signals, for example, a silicon substrate, an alumina substrate, a glass ceramic substrate, a multilayer ceramic substrate, and the like can be used.

The surface light receiving type semiconductor light receiving element 2 disposed on the substrate 1 includes, for example, a photodiode (PN photodiode / PIN photodiode or avalanche photodiode / MSM (Metal-Semiconductor-
Metal) photodiodes and the like are used, and these are mounted or mounted on the substrate 1 or disposed. The light receiving surface of the semiconductor light receiving element 2 is basically located on the upper part of the element 2 almost in parallel with the upper surface of the substrate 1,
The position is not limited to such a position, and may be located anywhere on the semiconductor light receiving element 2. However, depending on the position of the light receiving surface, it is necessary to perform an optimal design that can obtain the maximum light receiving efficiency, and to form an optical waveguide and an intermediate refractive index body 6 that match the optimal design.

The optical waveguide formed on the substrate 1 and the semiconductor light receiving element 2 has at least a lower clad part 3 and a core part 4, and preferably has an upper clad part 5.
Is a three-dimensional waveguide shape optical waveguide composed of three layers having the following. As a material for forming the optical waveguide, various optical materials can be used as long as they can form an optical waveguide having a three-dimensional waveguide shape on the substrate 1. Among them, an organic optical material, in particular, a siloxane polymer is preferably used. If the optical waveguide is made of a siloxane-based polymer, for example, by using a siloxane-based polymer containing a metal such as titanium (Ti) only in the core portion 4 or in the core portion 4 and the lower and upper clad portions 3 and 5, the titanium content can be reduced. The optical waveguide having a desired refractive index difference between the core portion 4 and the lower and upper clad portions 3 and 5 can be easily manufactured by controlling the core portion 4, and the light receiving efficiency with the semiconductor light receiving element 2 is maximized. Becomes easier to design.

As such a siloxane-based polymer,
Any resin may be used as long as it has a siloxane bond in the polymer skeleton. Examples thereof include polyphenylsilsesquioxane, polymethylphenylsilsesquioxane, and polydiphenylsilsesquioxane.

The metal contained in the core portion 4 and the cladding portions 3 and 5 is not limited to titanium, but may be germanium (Ge), aluminum (Al), erbium (Er), or the like. In order to form the core portion 4 containing these metals, a siloxane-based polymer layer to which the metal alkoxide is added may be formed and processed into desired shapes and dimensions.

In addition, as a material of the optical waveguide, there is transparency that can transmit light with low loss.
In addition, various materials can be used as long as a combination of a core member and a clad member that can obtain a desired difference in refractive index. As the organic optical material, in addition to the siloxane-based polymer, an optical material that can be applied in a solution state, such as fluorinated polyimide, polymethyl methacrylate (PMMA), and polycarbonate (PC), is preferably used.

With respect to the end face of the light receiving surface of the semiconductor light receiving element 2,
An intermediate refractive index body 6 located on the input side in the light propagation direction of the optical waveguide and disposed in front of the end face of the semiconductor light receiving element 2 so as to face the end face of the light receiving surface and the lower face of the core portion 4 of the optical waveguide. Should have an appropriate refractive index and shape according to the refractive index and shape of the optical waveguide and the semiconductor light receiving element 2 constituting the optical integrated circuit. Preferably, the lower and upper clad portions 3 and 5 and the core portion A combination of the refractive index and the shape having an effective refractive index equal to the effective refractive index of the optical waveguide composed of the three layers 4 and 4 is preferable. For example, when the refractive index of the intermediate refractive index body 6 is large, its thickness is reduced, and when the refractive index of the intermediate refractive index body 6 is small, its thickness is increased.

As a material for the formation, for example, for an optical waveguide made of a siloxane-based polymer, the refractive index of the core portion 4 of the optical waveguide constituting an optical integrated circuit such as PMMA is larger than that of the semiconductor light receiving element 2. Any material may be used as long as it has a refractive index smaller than the refractive index of the light-receiving surface of the above (1) and further has a small light loss such as light absorption. Therefore, a resin material containing a metal, a metal, and the like are not necessarily suitable as a material for forming the intermediate refractive index body 6 because of a light absorption loss, but in this case, an effect is obtained by optimally designing the shape. Propagating light can be coupled to the light receiving surface of the semiconductor light receiving element 2. As such a shape, for example, a shape having a structure in which the metal content is increased on the side opposite to the optical waveguide side of the intermediate refractive index body 6 arranged in parallel with the optical waveguide using a resin material containing metal. It is good to

The optical waveguide formed on the substrate 1 on which the semiconductor light receiving element 2 is disposed with the light propagation direction being parallel to the light receiving surface of the semiconductor light receiving element is formed by the thickness of the lower clad portion 3, that is, the substrate 1 The thickness up to the core portion 4 formed substantially in parallel with the substrate is formed to be greater than the thickness based on the result of an experiment conducted beforehand on a thickness of the material to prevent radiation loss due to the interaction with the substrate 1. I do.

In order to realize the structure of the optical integrated circuit board designed as described above, for example, first, a solution of a siloxane-based polymer as a material of the lower clad portion 3 is applied to the substrate 1 by applying an optical material solution to the substrate 1. The lower clad portion 3 is formed using a device such as a spin coater or a bar coater that can be dropped and applied, and a material for forming the intermediate refractive index body 6 is applied thereon using a spin coater or a bar coater. Then, the intermediate refractive index body 6 is patterned by etching. Equipment used for this etching includes, for example, ECR
(Electron Cyclotron Resonance), RIE (Reactive Ion Etching), laser, etc. can be employed, and the designed pattern shape can be processed by optimizing the etching conditions.

At this time, the sectional shape of the intermediate refractive index body 6 along the light propagation direction of the optical waveguide is not only a substantially square shape as shown in FIG. 1 but also a sectional view similar to FIG. As shown, the surface facing the end surface of the light receiving surface of the semiconductor light receiving element 2 and the lower surface of the core portion 4 of the optical waveguide may be formed into a substantially triangular shape having two orthogonal sides and an oblique side connecting these sides. By making the cross-sectional shape of the intermediate refractive index body 6 substantially triangular as shown in FIG. 2, the effective refraction when considered as a second optical waveguide composed of the intermediate refractive index body 6 and the clad portion 3 surrounding it. Since the index gradually approaches the effective refractive index of the semiconductor light receiving element 2, the effect of the coupling can be further increased.

Further, the portion on which the semiconductor light receiving element 2 is mounted is processed by etching in the same manner. After that, the semiconductor light receiving element 2 is mounted on the substrate 1 and the lower clad part 3 is formed again to provide a predetermined gap between the core part 4 of the optical waveguide and the semiconductor light receiving element 2. Then, a core portion 4 is formed thereon, and is similarly patterned by etching into a desired shape to form an optical waveguide.

The optical integrated circuit board of the present invention as shown in FIGS. 1 and 2 has a large number of semiconductor light receiving elements 14 disposed on a substrate 11 as shown in, for example, a perspective view in FIG. A core portion 13 of an optical waveguide optically coupled with each semiconductor light receiving element 14 is formed thereon, and further used for an optical integrated circuit module or the like in which a large number of optoelectronic devices such as an optical amplifier 15 are mounted. In the optical integrated circuit module, the size of the module can be reduced while the optical waveguide 13 and the semiconductor light receiving element 14 are optically coupled with high light receiving efficiency.

In FIG. 3, reference numeral 12 denotes an optical fiber for exchanging optical signals with the outside, and reference numeral 16 denotes an electrode portion formed on the substrate 11 for driving the optical amplifier 15. Further, a portion indicated by four parallel straight lines at a portion of the optical waveguide 13 on the input side (optical fiber 12 side) of the semiconductor light receiving element 14 in the light propagation direction by the optical waveguide 13 is provided with an intermediate refractive index body. It is a place that is.

[0030]

Next, a specific example of the optical integrated circuit board of the present invention will be described.

Example 1 First, a lower clad portion 3 was formed on an alumina substrate 1, and a part thereof was processed to form an intermediate refractive index member 6. Then, the surface light receiving type semiconductor light receiving element 2
And a step index type optical waveguide in which the lower and upper cladding portions 3 and 5 are made of a siloxane-based polymer, and the core portion 4 is made of a titanium-containing siloxane-based polymer.
An optical integrated circuit substrate having the same configuration as that of the example shown in FIG. 1 was manufactured. At this time, the refractive index of the core portion 4 and the cladding portions 3 and 5 are set to 1.450 and 1.445, respectively, and the width of the core portion 4 is set to 6
μm, the height was 6 μm, the thickness of the lower cladding portion 3 (the thickness from the substrate 1 to the core portion 4 formed parallel to the upper surface of the substrate 1) was 10 μm, and the thickness of the upper cladding portion 5 was 10 μm. The semiconductor light receiving element 2 used had a thickness of 1 μm and a light receiving surface area of 200 μm in diameter. The intermediate refractive index body 6 was processed to have a width of 200 μm, a height of 1 μm, and a length in the light propagation direction of 60 μm using fluorinated polyimide having a refractive index of 1.492. The end face of the intermediate refractive index member 6 and the end face of the light receiving surface of the semiconductor light receiving element 2 are in contact with each other.

Further, an upper clad portion 5 was formed on the core portion 4 using the same material as the lower clad portion 3.

When the coupling efficiency between the optical waveguide and the semiconductor light receiving element 2 of the optical integrated circuit substrate of the present invention thus manufactured was measured, it was about 17% which was about twice that of the optical integrated circuit substrate according to the prior art. It was confirmed that the coupling efficiency was as follows.

Although an alumina substrate was used as the substrate 1 in this embodiment, an aluminum nitride substrate, a silicon substrate, a glass-ceramic substrate, or the like may also have a good coupling efficiency.

Example 2 First, a lower clad portion 3 is formed on an alumina substrate 1 and a part thereof is processed to form an intermediate refractive index member 6.
Was formed. Thereafter, the surface light receiving type semiconductor light receiving element 2 was mounted, and the lower and upper cladding portions 3 and 5 were provided with a step index type optical waveguide composed of a siloxane-based polymer and the core portion 4 composed of a titanium-containing siloxane-based polymer.
An optical integrated circuit board having the same configuration as that of the example shown in FIG.
At this time, the refractive index of the core portion 4 and the cladding portions 3 and 5 are 1.450 and 1.445, respectively, and the width of the core portion 4 is 6 μm.
m, the height was 6 μm, the thickness of the lower cladding portion 3 (the thickness from the substrate 1 to the core portion 4 formed parallel to the upper surface of the substrate 1) was 10 μm, and the thickness of the upper cladding portion 5 was 10 μm. The semiconductor light receiving element 2 used had a thickness of 1 μm and a light receiving surface area of 200 μm in diameter. The intermediate refractive index member 6 is made of a material obtained by adding a metal to a fluorinated polyimide having a refractive index of 1.504, and has a width of 200 μm and a height of 1 μm.
m, and the length in the light propagation direction was 540 μm. The end face of the intermediate refractive index member 6 and the end face of the light receiving surface of the semiconductor light receiving element 2 are in contact with each other.

Further, an upper clad portion 5 was formed on the core portion 4 using the same material as the lower clad portion 3.

When the coupling efficiency between the optical waveguide and the semiconductor light receiving element 2 of the optical integrated circuit board of the present invention thus manufactured was measured, the coupling efficiency was about 50% higher than that of the conventional optical integrated circuit board. It was confirmed that it had.

The coupling efficiency to the semiconductor light receiving element 2 can be arbitrarily designed by changing the refractive index and the shape of the intermediate refractive index member 6.

When the optical waveguide and the semiconductor light receiving element 2 are considered as two parallel waveguides, the change in the coupling efficiency when the refractive index of the intermediate refractive index body 6 is changed and the light propagation of the intermediate refractive index body 6 The change in coupling efficiency when the length in the direction is changed,
5 and 6 are diagrammatically shown. The horizontal axis of FIG. 5 represents the refractive index n of the intermediate refractive index body 6, the horizontal axis of FIG. 6 represents the length L (μm) of the intermediate refractive index body 6 in the light propagation direction, and the vertical axes of both figures represent the coupling efficiency. Coupling efficiency is shown. In the legends in both figures, “square” indicates the behavior on the optical integrated circuit substrate of Example 1, and “taper” indicates the behavior on the optical integrated circuit substrate of Example 2.

From the results shown in FIGS. 5 and 6, the refractive index has an optimum value. When the refractive index has the optimum value, the effective refractive index of the optical waveguide composed of the core portion 4 and the lower and upper cladding portions 3 and 5 is obtained. Index, intermediate refractive index body 6 and lower cladding 3
It can be seen that the effective refractive index of the second optical waveguide composed of As for the length L of the intermediate refractive index body 6 in the light propagation direction, when the cross-sectional shape of the intermediate refractive index body 6 shows a substantially square shape, the coupling efficiency changes periodically with respect to the length L. However, since there is a length L having the maximum coupling efficiency, the length can be selected according to the processing accuracy. On the other hand, when the cross-sectional shape of the intermediate refractive index body 6 is substantially triangular, the coupling efficiency tends to increase while periodically changing with the length L. It can be seen that can be adjusted.

Although an alumina substrate was used as the substrate 1 in this embodiment, an aluminum nitride substrate, a silicon substrate, a glass-ceramic substrate, or the like also provided good coupling efficiency.

It should be noted that the above is only an example of the embodiment of the present invention, and the present invention is not limited to the embodiment. Various changes and improvements may be made without departing from the gist of the present invention. No problem. For example, the refractive index is gradually changed from the input side of the optical waveguide to the semiconductor light receiving element 2 so as to have the same effect as the change in the effective refractive index when the cross section of the intermediate refractive index body 6 has a substantially triangular shape. Is also good.
The change in the refractive index in this case can be achieved, for example, by adjusting the fluorine content of the fluorinated polyimide of the intermediate refractive index body 6 so that the refractive index gradually increases from the input side of the optical waveguide to the semiconductor light receiving element 2 side. Good. In the processing of the intermediate refractive index member 6, the intermediate refractive index member 6 may be formed on another substrate and then attached to the lower clad portion 3 to form the intermediate refractive index member.

Although FIGS. 1 and 2 show a case where the semiconductor light receiving element is located below the optical waveguide, the following structure may be adopted.

First, a lower clad portion is formed on a substrate, and a core portion is formed thereon. After forming a thin clad portion thereon and processing the intermediate refractive index body, the semiconductor light receiving element is mounted with the light receiving surface facing downward so that the light receiving surface is parallel to the optical waveguide. The intermediate refractive index member is located on the input side of the semiconductor light receiving element in the propagation direction of the optical waveguide, and is disposed so as to face the end face of the light receiving surface of the semiconductor light receiving element and the upper surface of the core portion of the optical waveguide. Then, an upper clad portion is formed so as to cover the intermediate refractive index body and the semiconductor light receiving element. Note that the upper cladding portion is not necessarily formed, and a structure in which the intermediate refractive index member and the semiconductor light receiving element are exposed to air without being covered with the upper cladding portion may be adopted.

Further, the structure may be such that the optical waveguide, the semiconductor light receiving element, and the intermediate refractive index body are arranged in a plane with respect to the substrate. First, form the lower cladding on the substrate,
A core part is formed thereon. The intermediate refractive index body is located on the input side in the direction of propagation by the optical waveguide of the semiconductor light receiving element,
The semiconductor light receiving element is arranged so as to face an end face of a light receiving surface of the semiconductor light receiving element and a side face of a core portion of the optical waveguide. The intermediate refractive index body is
An arbitrary shape may be formed on the side of the core portion by using photolithography technology, or a product manufactured on another substrate may be attached. An upper clad portion is formed so as to cover the core portion and the intermediate refractive index body. The semiconductor light receiving element is
A mounting hole is formed at the mounting position by etching such as RIE, and is mounted vertically on the substrate so that the light receiving surface faces the optical waveguide. The electrode portion of the semiconductor light receiving element is preferably configured such that the portion exposed on the substrate can be connected to electric wiring by wire bonding or the like.

[0046]

As described above, according to the optical integrated circuit substrate of the present invention, an optical waveguide is formed so as to be stacked on a surface light receiving type semiconductor light receiving element provided on the substrate. Therefore, the semiconductor light receiving element and the optical waveguide can be efficiently integrated on the same substrate, and the optical integrated circuit substrate on which the semiconductor light receiving element is mounted after the optical waveguide is formed on the substrate as in the related art. It is possible to reduce the size and height of the optical waveguide and to mount another optoelectronic device or the like on the optical waveguide. Therefore, it is particularly preferable to mount a plurality of semiconductor light receiving elements and optoelectronic devices on the substrate. Such an optical integrated circuit board can also realize a reduction in the size of the optical integrated circuit board.

According to the optical integrated circuit board of the present invention,
As the substrate, various substrates can be used as long as a substrate on which a semiconductor light receiving element can be formed or a substrate on which a semiconductor light receiving element can be mounted and mounted. More suitable substrates can be used for integration and high integration of optoelectronic devices.

According to the optical integrated circuit board of the present invention,
Before the end face on the input side in the light propagation direction by the optical waveguide of the semiconductor light receiving element, facing this end face and the core part of the optical waveguide, the refractive index is larger than the core part of the optical waveguide and is higher than the light receiving surface of the semiconductor light receiving element. By arranging a small intermediate refractive index body, for the propagating light leaked from the core portion incident on the end face of the light receiving surface, a large refractive index between the light receiving surface and the clad portion at the end face of the semiconductor light receiving element, for example. Since the change is reduced, the reflection of the incident light on the end face of the light receiving surface can be suppressed, and the light propagated by the optical waveguide can be efficiently optically coupled to the semiconductor light receiving element. An optical integrated circuit substrate having high optical coupling efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an embodiment of an optical integrated circuit substrate according to the present invention.

FIG. 2 is a sectional view showing another example of the embodiment of the optical integrated circuit substrate of the present invention.

FIG. 3 is a perspective view showing an example of an optical integrated circuit module using the optical integrated circuit substrate of the present invention.

FIG. 4 is a cross-sectional view illustrating an example of a conventional optical integrated circuit substrate.

FIG. 5 is a diagram showing a change in coupling efficiency with respect to a refractive index of an intermediate refractive index body in an embodiment of the optical integrated circuit substrate of the present invention.

FIG. 6 is a diagram showing a change in coupling efficiency with respect to the length of the intermediate refractive index body in the light propagation direction in the embodiment of the optical integrated circuit substrate of the present invention;

[Explanation of symbols]

 1 ... substrate 2 ... semiconductor light receiving element 3 ... lower cladding part of optical waveguide 4 ... core part of optical waveguide 5 ... upper cladding of optical waveguide Part 6 ... intermediate refractive index body

Claims (1)

[Claims] A semiconductor light-receiving element disposed on a substrate;
An optical waveguide having at least a lower cladding part and a core part, and formed in the vicinity of the semiconductor light receiving element with a light propagation direction parallel to the light receiving surface thereof; and an input of the light propagation direction by the optical waveguide of the semiconductor light receiving element An intermediate refractive index body which is located on the side and is arranged to face the end face of the light receiving surface of the semiconductor light receiving element and the core portion of the optical waveguide, the refractive index of which is larger than the core portion and smaller than the light receiving surface. An optical integrated circuit substrate, comprising: