JP2003337237A - Optical communication component and laminated optical communication module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication component which has high transmission efficiency of light in a waveguide and can be made small by steep bending of an optical path and to provide an optical communication module. <P>SOLUTION: In this optical communication component which has a substrate and the waveguide formed inside the substrate, wherein at least one end of the waveguide can optically coupled to an external optical path, the waveguide includes a cavity formed inside the substrate and a reflection film covering the wall surface of the cavity and transmits light inside the cavity. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication component used for optical communication and a laminated optical communication module for forming the optical communication component.

[0002]

2. Description of the Related Art In recent years, with the spread of the Internet, it has become necessary to transmit and receive a large amount of information such as music, moving images and computer data at high speed. For data transmission / reception using optical fibers, the transfer rate is 100 Mbp for home use.
s or more, and data can be transmitted and received at a speed of about 3 digits faster than a modem or ISDN using a telephone line which is widely used in ordinary households. Furthermore, in the backbone system, 10-40 Gbps
Has reached. In addition, in recent years, a new technology called optical multiplex communication has appeared, and it has become possible to further increase speed and capacity.

With the development of such optical communication, in the field of optical communication components, the development of a technique for optically coupling an optical waveguide such as an optical fiber and an element such as a light receiving element or a light emitting element is required. Expected to be

Conventionally, in the case of optically coupling an optical fiber and a light emitting element, light from the light emitting element is condensed by a lens and coupled to the optical fiber (Patent Document 1).

On the other hand, there is also a method of coupling an optical waveguide and a light emitting element or a light receiving element without using an optical system such as a lens. In the method of directly connecting the semiconductor laser and the optical fiber, the tip of the optical fiber is cut, and the outer shell ferrule is cut out into an L-shape so that chip bonding can be performed, and that portion is brought into close contact with the semiconductor laser to make the optical fiber. The center of the fiber core is aligned with the center of the light emitting point of the semiconductor laser chip (Patent Document 2). Further, in the method of directly optically coupling the semiconductor laser chip and the optical waveguide, a gap is provided between the end surface of the active layer of the semiconductor laser and the end surface of the optical waveguide, and the two are opposed to each other to directly optically couple the optical waveguide. (Patent Document 3).

In any of these conventional optical coupling methods, an optical distance is generated between the light emitting surface of the light emitting element and the optical waveguide, or various optical systems are provided between the light emitting element and the optical waveguide. However, it is difficult to make the light from the light emitting element enter the optical waveguide efficiently, and it is difficult to make the components compact.

From this point of view, there has been proposed an optical coupling structure which can realize many optical processing functions and can be easily made compact. For example, as a means for realizing a compact integrated optical circuit, an optical coupling device having a five-layer waveguide structure in which a plurality of substrates are three-dimensionally arranged is disclosed (Patent Document 4). However, although an example of a three-dimensional optical circuit device is shown in this document, a method utilizing the difference in refractive index between the ambient air and the substrate is adopted for connecting the vertical optical path and the horizontal optical path. . Therefore, so-called perfect coupling length is required for the optical power transition between the vertical optical path and the horizontal optical path. Therefore, the optical path cannot be sharply bent. Further, therefore, when a plurality of horizontal circuit boards are stacked to form a three-dimensional optical circuit, it is necessary to provide a predetermined space between the horizontal circuit boards, so that the horizontal circuit boards cannot be laminated and adhered to each other.

On the other hand, Patent Document 5 discloses an example in which a reflective layer is provided on the inner surface of the optical waveguide. However, this reflective layer is formed on the inner surface of a flexible tube for a laser beam machine. That is, it is not shown that the optical path is sharply bent, and the three-dimensional optical circuit is not disclosed. Further, although FIG. 1 of the same publication shows that the optical path of the conventional laser processing machine is composed of a space and a reflecting mirror,
The optical path is not formed inside the substrate.

Further, Patent Document 6 discloses forming a hollow waveguide made of gold. However, the gold light tube that remains as the outer shell is formed in a spiral shape rather than being bent sharply. If this light tube system is used for sharp bending, it becomes difficult to secure an optical path inside the tube.

Patent Document 7 discloses that a V groove is formed on the surface of a silicon substrate by anisotropic etching, a reflection film is formed on the slope, and an optical fiber is embedded in the V groove. The light emitting or light receiving element and the optical fiber are coupled via the reflection film. But with this method,
The optical fibers must be arranged in a straight line, and a waveguide that bends freely in a horizontal plane cannot be formed.

[0011] Patent Document 8 discloses that all of the upper surface, the lower surface and the side surface of the substrate on which the waveguide is formed are metallized in order to shield stray light from the waveguide substrate.
However, there is no disclosure of metallizing the waveguide itself and sharply bending the optical path.

[0012] Patent Document 9 describes an assembly of an optoelectronic device in which a groove portion is provided in a silicon substrate and a reflector is partially formed on an end face portion of the groove portion. In this device,
An optical fiber is inserted into the groove and a device is arranged above the reflector, whereby the optical fiber and the device are coupled via the reflector. However, in this device, since optical transmission to the device is realized by an optical fiber, there is a limit to downsizing the device.

Patent Document 10 describes a waveguide in which a resist layer which is a coating film is formed on a substrate, a cavity is formed in the resist, and a reflection film is formed on the inner wall of the cavity. . However, this waveguide is not a substrate,
It is formed in the resist layer formed thereon. Since the resist is easily deformed by the influence of the external environment (for example, temperature) or stress, it is difficult to secure sufficient durability in the waveguide formed in such a resist layer.

[0014]

[Patent Document 1] JP-A-61-93419

[0015]

[Patent Document 2] Japanese Patent Laid-Open No. 63-253315

[0016]

[Patent Document 3] Japanese Patent Laid-Open No. 3-39913

[0017]

[Patent Document 4] JP-A-61-148406

[0018]

[Patent Document 5] Japanese Patent Application Laid-Open No. 54-139847

[0019]

[Patent Document 6] JP-A-2-73311

[0020]

[Patent Document 7] Japanese Patent Laid-Open No. 10-170765

[0021]

[Patent Document 8] Japanese Patent Laid-Open No. 2001-133645

[0022]

[Patent Document 9] Japanese Unexamined Patent Publication No. Hei 2-9183

[0023]

[Patent Document 10] JP-A-5-264833

[0024]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art. It is possible to efficiently transmit light from an external optical path through a waveguide, and to make a sharp bend in the optical path. An object of the present invention is to provide an optical communication component and an optical communication module that can reduce the size of the component.

[0025]

To achieve the above object, one aspect of the present invention includes a substrate and a waveguide formed inside the substrate, and at least one end of the waveguide is an external optical path. An optical communication component that can be optically coupled to
The waveguide is an optical communication component that includes a cavity formed inside the substrate and a reflective film that covers a wall surface of the cavity, and transmits light in the cavity.

Another aspect of the present invention is a laminated optical communication module. The module includes a substrate, a vertical waveguide formed inside the substrate and transmitting light in a thickness direction of the substrate, and a horizontal waveguide formed inside the substrate and transmitting light in an in-plane direction of the substrate. The substrate includes a waveguide and an optical bending portion that optically couples the vertical waveguide and the horizontal waveguide. The substrate has a groove formed on a surface thereof, and a reflecting mirror is arranged at at least one end of the groove. A first substrate and the first
And a second substrate which is laminated in close contact with the surface of the substrate on which the groove is formed and which has a through hole formed at a position communicating with the portion of the groove where the reflection mirror is arranged, The horizontal waveguide includes a cavity formed by the groove and a reflection film that covers the wall surface of the cavity, and transmits light in the cavity. The vertical waveguide is formed by the through hole. And a reflective film that covers the wall surface of the cavity, wherein light is transmitted in the cavity,
The light bending portion includes the reflecting mirror, and changes the transmission direction of light from the thickness direction of the substrate to the in-plane direction or from the in-plane direction of the substrate to the thickness direction by reflection on the reflecting mirror surface. It is what makes me.

Another aspect of the present invention is an optical communication component in which a plurality of optical communication modules are optically coupled to each other, and at least one of the optical communication modules is the stacked optical communication of the present invention. An optical communication component that is a module.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION An optical communication component of the present invention comprises a substrate,
A waveguide formed inside the substrate, wherein at least one end of the waveguide is optically coupled with an external optical path, the waveguide being formed inside the substrate. And a reflection film that covers the wall surface of the cavity, and transmits light in the cavity.

The optical communication component having such a structure has a high light transmission rate because the inner wall of the waveguide is covered with the reflective film.

Further, according to the optical communication component, since the optical path can be sharply bent, the component can be downsized. When bending the optical path, forming a light bent portion in the waveguide,
In this light bent portion, the cavity wall surface of the waveguide may be inclined with respect to the light transmission direction. By coating this inclined surface with a reflective film, it can function as a reflecting mirror for changing the light transmission direction.

In the optical communication component, the substrate is
A laminated body including a first substrate having a groove formed on its surface and a second substrate closely laminated on the surface of the first substrate having the groove formed, wherein the cavity of the waveguide is It is preferably formed by a groove. Such an optical communication component has an advantage that it can be easily manufactured, and can be a waveguide having a complicated shape.

Further, the optical communication component includes an optical circuit element optically coupled to one end of the waveguide, and one end of the waveguide is optically connected to the external optical path via the optical circuit element. It is preferable that they can be bound together. As the optical circuit element, for example, a passive optical element can be used. Further, specific examples thereof include a diffraction grating, an optical filter, an optical switch, an attenuator and the like. By providing such an optical circuit element in an optical communication component, it is possible to demultiplex or combine incoming and outgoing light.

Further, the optical communication component includes a photoelectric conversion element optically coupled to one end of the waveguide, and an electric wiring formed on the surface of the substrate, wherein the photoelectric conversion element is the electric circuit. Preferably, it can be electrically connected to an external electric circuit via a wiring. Such an optical communication component has an advantage that it can be applied to a wide range because it can perform mutual conversion between an optical signal and an electric signal.

In the optical communication component, it is preferable that the cavity forming the waveguide is filled with a light transmissive medium. According to this preferable example, the stability of the waveguide against external stress can be improved, and the influence of dew condensation on the optical characteristics of water and mold can be minimized.
As the light transmissive medium, for example, a resin such as an ultraviolet curable resin can be used.

Further, in the optical communication component, it is preferable that the reflection film is a metal film. According to this preferable example, since good reflection characteristics are obtained, the transmission light rate of the waveguide is further improved. Further, by forming the reflective film from metal, there is an advantage that the reflective film can be used as electric wiring. Moreover, it is preferable to use a plating method for forming the metal film. This is because a uniform metal film can be formed.

Further, the optical communication component includes a support body in which a groove for mounting an optical fiber is formed, and one end of the groove and one end of the waveguide face each other in the support body. It is preferable that the waveguide is optically coupled to the optical fiber when the optical fiber is mounted in the groove. A coupling lens is mounted on the support so as to be located between one end of the groove and one end of the waveguide, and one end of the waveguide is mounted when an optical fiber is mounted in the groove. Is preferably optically coupled to the optical fiber via the coupling lens. The coupling lens is preferably made of silicon. By using silicon having a high refractive index, the curvature of the lens can be reduced, so that the aberration can be reduced and the spot diameter can also be reduced.

Further, it is preferable that a metal film is formed on the wall surface of the groove for mounting the optical fiber of the support. Thereby, the optical fiber can be mounted on the support by metal joining such as soldering.

When a coupling lens is mounted on the support, a metal film is formed on a portion of the support where the coupling lens is arranged, and a metal film is formed on a side surface of the coupling lens. It is preferable that both are metal-bonded.

Further, the optical communication module of the present invention includes a substrate, a vertical waveguide formed inside the substrate and transmitting light in the thickness direction of the substrate, and formed inside the substrate. A horizontal waveguide that transmits light in the in-plane direction,
An optical bent portion that optically couples the vertical waveguide and the horizontal waveguide, and the substrate has a groove formed on its surface,
A first substrate having a reflecting mirror arranged on at least one end of the groove and a surface of the first substrate on which the groove is formed are closely laminated and communicate with a portion of the groove where the reflecting mirror is arranged. A second substrate having a through hole formed at a position, wherein the horizontal waveguide includes a cavity formed by the groove, and a reflection film covering a wall surface of the cavity. Wherein the vertical waveguide includes a cavity formed by the through hole and a reflective film covering a wall surface of the cavity, and the light is transmitted in the cavity. The light bending portion includes the reflecting mirror, and the light transmitting direction is changed from the thickness direction of the substrate to the in-plane direction by the reflection on the reflecting mirror surface, or from the in-plane direction of the substrate to the thickness direction. It is characterized by being changed.

According to such a configuration, it is possible to form a three-dimensional circuit by providing the light bending portion in the module, and it is possible to realize a compact optical communication module. Further, since the reflective film is formed on the waveguide, the light transmission rate is good. Further, since the substrates are laminated in close contact, the plate can be made thin.

Here, the "optical communication module" can be used alone as an optical communication component, but normally, a plurality of optical communication modules are coupled to each other to form one optical communication component. To do. Therefore, the optical communication module also has a property as a component forming an integrated optical circuit.

In the above optical communication module, further,
It is preferable that an optical circuit element optically coupled to at least one of the horizontal waveguide and the vertical waveguide is included in the substrate. The same optical circuit element as described above can be used. By providing such an optical circuit element in the module, it is possible to demultiplex or combine incoming and outgoing light.

In the optical communication module,
Further, including a photoelectric conversion element optically coupled to one end of the waveguide, and electrical wiring formed on the substrate surface,
It is preferable that the photoelectric conversion element can be electrically connected to an external electric circuit via the electric wiring. Such an optical communication module has an advantage that it can be applied to a wide range because it can perform mutual conversion between an optical signal and an electric signal.

In the optical communication module,
It is preferable that the reflection film and the reflection mirror are metal films. According to this preferable example, since good reflection characteristics are obtained, the transmission light rate of the waveguide is further improved. Further, by forming the reflective film from metal, there is an advantage that the reflective film can be used as electric wiring.
Moreover, it is preferable to use a plating method for forming the metal film. This is because a uniform metal film can be formed.

In the optical communication module,
It is preferable that the cavity forming the vertical waveguide and the horizontal waveguide is filled with a light transmissive medium. According to this preferable example, the stability of the waveguide against external stress can be improved, and the influence of dew condensation on the optical characteristics of water and mold can be minimized. As the light transmissive medium, for example, a resin such as an ultraviolet curable resin can be used.

Next, preferred embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view showing an example of an optical communication component according to the present invention. Also, in FIG.
It is sectional drawing of the said optical communication component. This optical communication component includes an optical circuit unit 1 including an optical circuit element and a waveguide, and a coupling unit 2 for optically coupling the optical circuit unit 1 with an external optical path (not shown). There is.

In the coupling section 2, the optical coupling components 14 and 15 are mounted on the support 11. The optical circuit unit 1 is composed of a laminated body in which a plurality of substrates 21, 31, and 41 are closely laminated, and a waveguide is formed inside the laminated body. This waveguide is arranged so that one end thereof faces the optical coupling component 15. The photoelectric conversion element 5 is provided on the uppermost substrate 41 constituting the optical circuit unit 1.
1 is implemented. The photoelectric conversion element 51 is arranged such that its light-receiving surface or light-emitting surface faces one end of the waveguide. Further, an electric wiring 52 and an electronic component 53 are arranged in the optical circuit section 1. In addition, the bottom substrate 2
1 has a metal layer 101 laminated thereon.

As shown in FIG. 2, the transmitted light that has entered the optical circuit section from the coupling section reaches the photoelectric conversion section 51 via the waveguide formed in the substrate. On the contrary, the transmitted light that has entered the optical circuit unit from the photoelectric conversion unit 51 is guided from the coupling unit to the external optical path (not shown) via the waveguide formed in the substrate.

Next, each member constituting the optical communication component will be described in detail.

(1) Coupling Portion The coupling portion is provided with an optical coupling component for optically coupling the waveguide and the external optical path, and a support for supporting this optical coupling component. Although FIG. 1 illustrates the case where an optical fiber and a coupling lens are used as the optical coupling component, the optical coupling component is not limited to these.

As the support 11, for example, at least one substrate selected from the group consisting of a silicon substrate, a plastic substrate and a glass substrate can be used. Further, as the support body 11, it is also possible to use an optical bench made of silicon or the like.

FIG. 3 is an external perspective view showing an example of the support 11. As shown, the surface of the support 11 is provided with a groove 12 for mounting the optical fiber 14 and the coupling lens 15.
(Hereinafter, referred to as “mounting groove”). The mounting groove 12 is preferably parallel to the optical axis of the optical fiber to be mounted and the optical axis of the coupling lens, and has a shape in which the bottom of the groove is narrower than the upper portion (opening). That is,
The sidewall surface of the mounting groove is preferably a surface parallel to the optical axis and inclined with respect to the substrate surface. Examples of the shape of the mounting groove 12 include a V-shaped groove and an inverted trapezoidal groove.

As a method of forming the mounting groove 12, when a silicon substrate is used as the support 11, for example, after forming a mask pattern having an opening at a position where the groove is formed on the surface of the silicon substrate, the substrate surface is formed. The method of etching is mentioned. As the etching, it is preferable to adopt anisotropic etching. As the anisotropic etching, for example, wet etching can be adopted. In this case, potassium hydroxide (KOH), sodium hydroxide (NaOH), tetramethylammonium hydroxide (TMA) is used as the etching agent.
H), hydrazine (EPW), HgCl ₂ , K ₂ Fe (C
N) ₆ or the like can be used. For example, when the (100) plane of silicon is etched using these etching agents, the surface ((100) plane) is
V formed by the (111) plane inclined about 54.7 ° from
A groove (vertical angle of about 70 °) can be formed. Also,
When the opening width of the mask is increased, the V-shaped groove has a bottom surface of the (100) plane, so that an inverted trapezoidal groove can be formed. When using a glass substrate and a plastic substrate, for example, a method of forming a groove having a desired shape by molding can be mentioned.

Further, the mounting groove 12 is formed on the surface of the support 11.
A plurality of grooves 13 (hereinafter, referred to as “bonding grooves”) are formed so as to intersect with. In this embodiment, the optical fiber and the coupling lens are fixed to the mounting groove 12 by filling the adhesive groove 13 with an adhesive. When mounting an optical fiber, etc. in the mounting groove of the optical bench, directly fill the mounting groove with an adhesive and place the optical fiber etc. on the adhesive so that the optical fiber floats from the mounting groove and is fixed. May be However, in this embodiment,
Since the optical fiber or the like is fixed to the mounting groove 12 by filling the adhesive groove 13 crossing the mounting groove 12 with the adhesive, the above-mentioned problem does not occur, and the optical fiber or the like is fixed without disturbing its function. can do. The width and the depth of the adhesive groove 13 are not particularly limited, but the adhesive groove 13 may be filled with the adhesive by a capillary action.
The thickness is preferably 0 to 500 μm, more preferably 50 to 2
It is preferably set to 00 μm. Further, the number of the bonding grooves 13 is not particularly limited, and can be appropriately set according to the dimensions of the optical fiber or the coupling lens to be mounted, and for example, 1 to 20, preferably 5 to 10. Is. Further, the interval between the bonding grooves 13 is not particularly limited, but from the viewpoint of increasing the bonding strength,
It is preferably 0.5 to 3 mm, more preferably 1 to 2 mm.

As a method of forming the bonding groove 13, for example, a method of forming by mechanical processing using dicing can be mentioned. It can also be formed by etching. In this case, for example, a flattening resist is applied to the mounting groove, dried, and then an inorganic film is formed thereon by spin coating (SOG: Spin On Glass), and then a resist is applied thereon. , An opening corresponding to the bonding groove is formed in this to form a mask pattern, and thereafter,
It is possible to employ a method in which the SOG, the planarizing resist, and the substrate are etched to form a bonding groove, and then the resist and SOG are removed.

The optical fiber 14 and the coupling lens 15 are mounted on the support 11 having the mounting groove 12 and the bonding groove 13. This mounting can be performed using an adhesive as described above, and as the adhesive, for example, an ultraviolet curable resin or the like can be used.

As the optical fiber 14, any conventionally known one can be used as long as it transmits light.
The optical fiber 14 may be either a glass fiber or a plastic fiber, but a silica glass fiber is preferable from the viewpoint of light loss and the like. Also,
The coupling lens 15 may be any one that can efficiently guide the light transmitted through the optical fiber 14 to the waveguide, or can efficiently guide the light transmitted inside the waveguide to the optical fiber 14, for example, A GRIN lens, a ball lens, a molded lens or the like can be used. The material is not particularly limited, but glass, silicon, or the like can be used, for example.

(2) Optical Circuit Section The optical circuit section has a structure in which a plurality of substrates are laminated in close contact, and a waveguide is formed inside the laminated body. Further, the optical circuit unit includes, as a waveguide, a vertical waveguide that transmits light in the thickness direction of the substrate and a horizontal waveguide that transmits light in the plane direction of the substrate. The vertical waveguide and the horizontal waveguide Are preferably optically coupled. This makes it possible to construct a three-dimensional optical path in which the waveguides are three-dimensionally connected. Further, it is preferable that an optical circuit element is arranged inside or on the surface of the laminate. In this case, an optical circuit is constructed by coupling this element with the waveguide.

A specific example of the optical circuit section will be described below.
This will be described with reference to the drawings.

As shown in FIGS. 1 and 2, in the optical circuit unit 1, the first stage substrate 21, the second stage substrate 31, and the third stage substrate 41 are directly arranged in this order. It is composed of a laminated body formed by closely laminating.

As each substrate, at least one substrate selected from the group consisting of a silicon substrate, a plastic substrate and a glass substrate can be used, but a silicon substrate or a glass substrate is preferable from the viewpoint of stability.
These substrates may be used in combination with different types of substrates, but from the viewpoint of stability against heat cycle and adhesion between the substrates, it is preferable to use the same type of substrate, particularly to use silicon substrates together. .

A first horizontal waveguide and an optical circuit element coupled to one end of the first horizontal waveguide are formed on the first-stage substrate 21. Here, a diffraction grating is used as the optical circuit element. Second stage substrate 3
A first horizontal waveguide is formed on the first substrate 1, and a vertical waveguide is formed on the third substrate 41. In addition,
Between the first horizontal waveguide and the second horizontal waveguide,
And between the second horizontal waveguide and the vertical waveguide,
Optically coupled by a light bend with a reflector. As a result, the first horizontal waveguide, the second horizontal waveguide, and the vertical waveguide are connected to form a three-dimensionally extended three-dimensional optical path. In addition, the third-stage substrate 41
A photoelectric conversion element is arranged at a predetermined position on the surface of and is optically coupled to the vertical waveguide. Furthermore, the third
Electronic components are arranged at predetermined positions on the surface of the substrate 41 of the tier, and are electrically connected to the photoelectric conversion elements via electric wirings 52. Further, a metal layer is laminated on the back surface of the first stage substrate.

Next, each of the above substrates will be described in detail.

First Stage Substrate FIG. 4 is an external perspective view showing an example of the first stage substrate 21. FIG. 5 is a partially enlarged view showing a portion of the first stage substrate on which the waveguide and the optical circuit element are formed.

As shown in FIG. 5, a groove serving as the first horizontal waveguide 26 is formed on the surface of the first-stage substrate 21. The groove forms a cavity when the second-stage substrates are laminated, and the cavity functions as a light transmission path. One end of the first horizontal waveguide 26 is optically coupled to the waveguide formed on the second stage substrate. The cross-sectional shape of this groove is not particularly limited.

A diffraction grating 28, which is an optical circuit element 28, is formed on the surface of the first-stage substrate 21. As shown in FIG. 5, the diffraction grating 28 is formed by forming a concave portion on the surface of the substrate 21 and forming a periodic structure on the wall surface of the concave portion. The first horizontal waveguide and the diffraction grating 28 are optically coupled. The coupling method is not particularly limited, but from the viewpoint of enhancing the light transmission efficiency, as shown in the figure, a groove forming the first horizontal waveguide 26 and a recess forming the diffraction grating 28 are formed. It is preferable that they are communicated with and integrated with each other. Further, the entrance to the diffraction grating 28 is coupled to the external optical path (not shown) via the coupling section.

6 to 8 are views showing an example of the first horizontal waveguide 26. As shown in FIG. 6 and 7 show AA ′ of FIG.
It is a sectional view and a BB 'section. In addition, FIG.
FIG. 3 is a partially enlarged view showing a bent portion of the horizontal waveguide of FIG.

As shown in FIG. 6, the first horizontal waveguide 26
A reflective film 27 is formed on the wall surface of the groove. By forming such a reflection film 27, light can be totally reflected in the waveguide and the light can be efficiently transmitted. Various metal films can be used as the reflective film 27,
Preferably, a metal film such as Au, Ag, Ni and Cu can be used. The thickness of the metal film is not particularly limited, but is, for example, 0.05 to 5 μm, preferably 0.10 to 2 μm.

In order to guide the light transmitted through the first horizontal waveguide to the waveguide formed on the second-stage substrate, the light transmission direction at the coupling portion between the waveguides is set to the plane of the substrate. It is necessary to change from the inward direction to the thickness direction. In the present embodiment, as shown in FIG. 7, the first horizontal waveguide 26
The change in the light transmission direction is realized by providing the light bending portion 29 in the portion of the second stage substrate that is coupled to the waveguide. The light bending portion 29 is configured by disposing a reflecting mirror at the end of the waveguide.

Since one end of the first horizontal waveguide 26 is optically coupled to the diffraction grating 28 and the other end thereof is coupled to the waveguide formed on the second-stage substrate, The shape is suitable for coupling with both. Therefore, as shown in FIG. 8, the first horizontal waveguide may be bent. By bending the waveguide in this way, the planar area of the first-stage substrate can be reduced, and a more compact optical communication component can be realized. In this case, in the bent portion of the waveguide, it is necessary to change the light transmission direction within the same plane parallel to the substrate surface. In the present embodiment, as shown in FIG. 8, the change in the light transmission direction is realized by providing the light bent portion 29 in the bent portion of the first horizontal waveguide 26. Light bending part 29
Is constructed by disposing a reflecting mirror in the bent portion of the waveguide.

As shown in FIGS. 7 and 8, the light bending portion 2
In 9, the reflecting mirror is provided so as to be inclined with respect to the transmission direction before and after the bending of light. This reflecting mirror can be formed by forming a taper at the terminal end or the bent portion of the groove forming the first horizontal waveguide 26 and covering the taper with the reflecting film 27. Further, also in manufacturing the first substrate, it is preferable to integrally form the reflecting film 27 on the wall surface of the groove and the reflecting mirror. As the reflective film 27,
A metal film similar to that described above can be used. The inclination angle of the taper is selected so as to be inclined with respect to the transmission direction before and after the bending of light. Therefore, it can be appropriately selected according to the shape of the coupling portion of the first horizontal waveguide with the waveguide of the second stage substrate, the shape of the bent portion, and the like. For example,
As shown in FIGS. 7 and 8, when the light transmission direction is changed substantially vertically, the taper inclination angle is preferably about 45 °.

As described above, the groove forming the first horizontal waveguide 26 forms a cavity when the second-stage substrates are stacked, and this cavity functions as a light transmission path. The cavity may remain hollow, but it is preferably filled with a light transmissive medium in order to prevent the light transmission efficiency from being lowered due to the influence of moisture in the air that enters the optical communication component. Examples of the light transmissive medium include light transmissive resins such as acrylic resin, fluorinated polyimide resin, and fluorinated epoxy resin. It may also be a fluid such as a light transmissive gel.

Second Stage Substrate FIG. 9 is an external perspective view showing an example of the second stage substrate 31.

As shown in the figure, a groove serving as the second horizontal waveguide 32 is formed on the surface of the second-stage substrate 31.
The groove forms a cavity when the third-stage substrates are stacked, and the cavity functions as a light transmission path.
The second horizontal waveguide 32 functions as an optical wiring for wiring an optical circuit in the second stage substrate. In addition, in FIG.
Although an example in which four waveguides are formed is shown, the number of waveguides is not particularly limited and is appropriately determined according to the purpose. Usually, the same number of waveguides as the number of waveguides formed on the first stage substrate is formed.

FIGS. 10 to 12 are views showing an example of the second horizontal waveguide, and are cross-sectional views taken along the line AA 'of FIG. 9, respectively.
It is a BB 'cross section and a CC' cross section.

As shown in FIG. 11, the second horizontal waveguide 3
A reflective film 33 is formed on the wall surface of the groove to be 2, similarly to the first horizontal waveguide. The material and film thickness of the reflective film 33 are similar to those of the first horizontal waveguide.
The cavity forming the second horizontal waveguide 32 may remain hollow as in the case of the first horizontal waveguide, but is preferably filled with a light transmissive medium. The material of the light transmissive medium is as described above.

One end of this second horizontal waveguide 32 is optically coupled to one end of the above-mentioned first horizontal waveguide 26. As shown in FIG. 10, the first horizontal waveguide 26 and the second horizontal waveguide 26
In the coupling portion with the horizontal waveguide 32, an opening for connecting both the waveguides is formed in the second-stage substrate 31. Substrate 3 from the first horizontal waveguide 26 to the second stage
When incident on 1, the light is transmitted in the thickness direction of the substrate,
Pass through the opening. The incident light passing through this opening is
In order to guide the light to the horizontal waveguide 32, it is necessary to change the light transmission direction from the thickness direction of the substrate to the in-plane direction.
In the present embodiment, as shown in FIG. 10, the light bent portion 29 of the first horizontal waveguide 26 of the second horizontal waveguide 32.
By providing the light bending portion 34 in a portion facing
This change in the light transmission direction is realized.

Further, the other end of the second horizontal waveguide 32 is optically coupled to one end of the waveguide formed on the third stage substrate. FIG. 12 shows a coupling portion of the second horizontal waveguide 32 with a waveguide formed on the third stage substrate. In order to guide the light transmitted through the second horizontal waveguide 32 to the waveguide formed on the substrate of the third stage, the light transmission direction at the coupling portion between the waveguides should be the in-plane direction of the substrate. To the thickness direction. In this embodiment, FIG.
As shown in FIG. 2, by providing the light bending portion 34 in the portion of the second horizontal waveguide 32 that is coupled to the waveguide formed on the third stage substrate, the change in the light transmission direction is caused. Has been realized.

As shown in FIG. 12, the light bending portion 34 is constructed by disposing a reflecting mirror at the end of the waveguide. This reflecting mirror can be formed by providing a groove in the waveguide with a taper and covering the groove with a reflecting film 33, as in the case of the first stage substrate.

Further, as in the case of the first stage substrate, the horizontal waveguide may be bent in the plane of the substrate also in the second stage substrate. In this case, as in the case of the first-stage substrate, the bent portion of the horizontal waveguide can be provided with a light bending portion formed of a reflecting mirror.

Third Stage Substrate As shown in FIG. 1, a photoelectric conversion element 51 is mounted on the surface of the third stage substrate 41. As the photoelectric conversion element 51, for example, a light receiving element such as a photodiode (PD), a light emitting element such as a light emitting diode (LED) and a laser diode (LD), or the like is used. Further, on the surface of the substrate 41 of the third stage, electronic components 5 such as LSI are
3 has been implemented. Further, an electric wiring 52 is formed on the surface of the substrate 41, and the wiring 52 electrically connects the photoelectric conversion element 51 and the electronic component 53.

As shown in FIG. 2, on the third-stage substrate 41, a vertical waveguide is provided at a portion where the photoelectric conversion element 51 is mounted so as to face the light receiving surface or the light emitting surface of the photoelectric conversion element 51. Through holes for forming 42 are formed. This through hole is usually formed substantially perpendicular to the substrate 41, and its cavity functions as a light transmission path.
Moreover, one end of the vertical waveguide 42 is optically coupled to one end of the second horizontal waveguide 32 described above. As a result, the light vertically raised by the light bending portion 34 arranged at the end of the second horizontal waveguide 32 of the second-stage substrate is transmitted to the photoelectric conversion element 51 via the vertical waveguide 42. I can guide you.

Further, as shown in FIG. 2, the vertical waveguide 42
On the wall surface of the through hole that becomes, like the first horizontal waveguide,
The reflective film 43 is formed. The material and film thickness of the reflective film 43 are the same as those of the first horizontal waveguide. The cavity forming the vertical waveguide 42 may remain hollow as in the first horizontal waveguide, but is preferably filled with a light transmissive medium. The material of the light transmissive medium is as described above.

The optical circuit section 1 is constructed by joining the first-stage, second-stage, and third-stage substrates 21, 31, 41. As described above, optical circuits (optical circuit elements, waveguides, etc.) are formed on the substrate of each stage, and by joining these, the optical circuits of the respective substrates are connected,
A three-dimensional three-dimensional optical path is constructed.

The light transmission operation in this three-dimensional optical path will be described by taking as an example the case where the photoelectric conversion element is a light receiving element such as a photodiode. In this case, this optical circuit section can function as a demultiplexer. First, an optical signal enters the first-stage substrate 21 from the external optical path through the optical fiber 14 and the coupling lens 15 of the coupling section 2,
It is guided to the diffraction grating 28. As shown in FIG. 5, the optical signal has wavelength components (λ ₁ ,
λ ₂ , λ ₃ , λ ₄ , and the first horizontal waveguide 2
6 and guided in the plane of the first-stage substrate 21. Then, as shown in FIG. 10, the first horizontal waveguide 2
The light transmitted through 6 is reflected by the reflecting mirror of the light bending portion 29 and rises substantially vertically, passes through the opening formed in the second-stage substrate 31, and then reaches the second-stage substrate 31. Incident. Then, it is guided to the second horizontal waveguide 32 by the reflecting mirror of the light bending portion 34 provided on the second-stage substrate 31, and guided in the plane of the second-stage substrate 31. Then, as shown in FIG. 2, the light transmitted through the second horizontal waveguide 32 is reflected by the reflecting mirror of the light bending portion 34 provided at the end of the second horizontal waveguide 32, and the third stage Incident on the substrate 41. And the third
The photoelectric conversion element 51 is reached via the vertical waveguide 42 provided on the substrate 41 of the step.

When the photoelectric conversion element is a light emitting element such as a light emitting diode (LED) or a laser diode (LD), the optical circuit section can function as a multiplexer. In this case, the light emitted from the photoelectric conversion element is transmitted in the opposite direction to the above, is combined in the diffraction grating, and is guided to the external optical path via the coupling section.

Next, a method of forming the optical circuit section will be described.

First, a first stage substrate is manufactured. A groove that serves as a first horizontal waveguide and a recess that serves as a diffraction grating are formed on the surface of the substrate. When using silicon as the substrate,
As a forming method, for example, a method using lithography and etching can be adopted. Specifically, first, a resist is applied on a substrate, a desired diffraction grating pattern and a waveguide pattern are transferred onto the resist by lithography, and then the resist is developed. As a result, the resist is patterned into a shape having a desired diffraction grating pattern and waveguide pattern opening. Then, by etching the substrate using this resist as a mask, it is possible to form a groove and a recess having a predetermined shape. The etching is not particularly limited, but dry etching is preferably adopted. The etching conditions can be appropriately selected according to the desired groove depth and the like.

Further, a taper for forming a light bent portion is formed at one end of the groove which becomes the first horizontal waveguide. The formation of this taper can be similarly performed by lithography and etching. Further, if a gray scale mask is used as an exposure mask during lithography, the resist itself can be patterned into a tapered shape. Therefore, if etching is performed along this resist pattern, the groove for the waveguide can be formed. It is also possible to form the taper and the taper at the same time.

After the etching, a reflective film is formed on the wall surface of the groove, but it is preferable to form an oxide film on the surface of the substrate (including the wall surface of the groove) prior to this step. When a silicon substrate is used, as a method of forming this oxide film, for example, a chemical vapor deposition (CVD) method, a thermal oxidation method, or the like can be adopted. When a glass substrate or a plastic substrate is used, for example, chemical vapor deposition (C
VD) method.

After forming the oxide film, a metal film serving as a reflection film is formed on the wall surface of the groove. At this time, a metal film is also formed on the taper, thereby forming a reflecting mirror of the light bending portion. As a method of forming a metal film, for example, a vapor deposition method,
Although a sputtering method, a plating method, etc. can be mentioned, it is preferable to adopt a plating method, particularly an electroless plating method, because a film can be formed uniformly in the details.

An example of metal film formation by electroless plating will be described. First, before performing the plating, the groove and the recess of the substrate are pretreated. Examples of the pretreatment include a treatment in which catalyst nuclei for causing an electroless plating reaction are attached to the grooves and recesses of the substrate. For example, when forming a layer containing Ni by electroless plating, as a pretreatment, a treatment containing a solution containing Pd catalyst nuclei is brought into contact with the grooves and recesses of the substrate and the Pd catalyst nuclei are attached to the surface thereof. Then, an electroless nickel (Ni) plating solution is brought into contact with the groove and the recess of the substrate to form a NiP layer. Then, this is treated with a substitution type electroless gold (Au) plating bath. As a result, part of Ni in the NiP layer is replaced with Au, and the Au layer is formed on the surface of the NiP layer.
By this operation, a metal film made of NiP / Au can be formed.

A second-stage substrate and a third-stage substrate are manufactured by a method substantially similar to the above.

When forming a waveguide, a diffraction grating, etc. using a glass substrate, lithography and etching can be similarly adopted. Alternatively, glass molding, which is conventionally performed, may be adopted. When a plastic substrate is used, a mold having a desired waveguide and diffraction grating shape is manufactured for each substrate by using silicon, glass, or the like, and the mold can be formed by resin molding. .

Next, the above-mentioned substrates are laminated and bonded to each other. By joining the substrates, the waveguide and the optical circuit element formed on each substrate communicate with each other to form a three-dimensional optical path.

When a silicon substrate is used, the substrates can be joined by, for example, a diffusion joining method. The diffusion bonding method is a method of chemically bonding Si on the surface of a silicon substrate at the interface of each substrate by performing heat treatment in a state where the silicon substrates are superposed on each other. The heat treatment temperature is, for example, 900 to 1100 ° C., preferably 1000 ° C.
And the processing time is, for example, 1 to 5 hours. Also,
The heat treatment is preferably carried out in an inert atmosphere,
It is particularly preferable to carry out under a nitrogen atmosphere.

When a plastic substrate is used, it can be carried out, for example, by ultrasonic welding. Alternatively, they may be joined using an adhesive such as an ultraviolet curable resin. When glass substrates are used, they can be bonded using an adhesive such as an ultraviolet curable resin.

It is also possible to bond different types of substrates such as glass and plastic and glass and silicon.
In this case, the glass and the plastic can be bonded by using an adhesive such as an ultraviolet curable (UV) resin, and the glass and the silicon can be bonded by anodic bonding.

Further, in the above description, the formation of the reflection film for covering the wall surface of the waveguide is carried out for each substrate before joining the substrates. However, it is preferable to bond the substrates to communicate the cavities (grooves, through holes, etc.) formed in each substrate and then collectively form the reflection film on the wall surfaces of the communicated cavities. In this way, by integrating the cavities that form the optical circuit and forming the reflective film collectively in the cavities of the respective substrates, light leakage from the optical circuit can be suppressed as much as possible.

Further, in this case, the formation of the oxide film, which is performed prior to the formation of the reflection film, can be collectively performed after the substrate bonding, particularly when the thermal oxidation method is adopted. However, when the chemical vapor deposition method is adopted, it is preferable to perform it for each substrate.

In this case, the reflection film is formed, for example, by joining the substrates and then immersing the obtained laminated body in various liquids for performing electroless plating, or formed on the laminated body. It can be carried out by forcibly injecting the various liquids into the cavity. It is particularly effective to carry out the immersion in a vacuum or a reduced pressure atmosphere. The forced injection can be carried out using, for example, a microsyringe such as a syringe, a micropump, or the like.

By the above method, a hollow waveguide whose wall surface is coated with a reflection film can be formed. Further, it is preferable that the waveguide is filled with a light transmitting medium for each wavelength. . This step can be performed, for example, by injecting the medium into a cavity when the medium is a liquid. When a resin is used as the medium, for example, an uncured and fluid photocurable resin is injected into the cavity by forced injection, such as with a microsyringe, and then light such as ultraviolet light is guided. A method of irradiating from the waveguide entrance to cure the resin in the waveguide can be used. At this time, since the reflective film is formed in the waveguide, light can be efficiently propagated in the waveguide, and the resin in the waveguide inside the substrate can also be efficiently cured.

When the reflection film of the waveguide is collectively carried out after the substrate is bonded, a step of expelling the water contained in the plating solution from the inside of the cavity of the waveguide is carried out before the filling of the light transmitting medium. It is preferable. This step can be performed, for example, by injecting an inert gas such as nitrogen gas into the cavity.

After the above processing, electric wiring is formed on the surface of the third stage substrate. The electric wiring can be formed by a conventionally known method, for example, a method of forming a metal film by a sputtering method, an evaporation method or the like, and then patterning the metal film by lithography and etching. It is also possible to adopt the lift-off method. Further, a plating method can be adopted as a film forming method for electric wiring. Further, the photoelectric conversion element and the electronic component are mounted on the surface of the third stage substrate. The mounting can be performed using, for example, solder, an adhesive, or the like.

Further, as shown in FIG. 1, in the optical circuit section 1, the metal layer 101 is laminated on the back surface of the substrate 21 (first stage substrate) of the lowermost layer. Depending on the types of the photoelectric conversion element and the electronic component mounted in the optical circuit section, heat may be generated during the operation. For example, when a laser diode is used as the photoelectric conversion element, heat is generated when light is emitted. In the present embodiment, by stacking the metal layer 101 on the back surface of the substrate 21 which is the lowermost layer, even if such heat is generated, the heat accumulated in the substrate is efficiently radiated through the metal layer. be able to.

By laminating the metal layer 101, toughness is imparted to the substrate, which makes it difficult to crack. For example, even if the thickness of the substrate is 100 μm or less, by stacking a metal layer, it is possible to impart toughness without practical damage.

As the metal forming the metal layer 101, for example, those having good thermal conductivity such as Cu, Ni, Cr are desirable. The thickness of the metal layer 101 is, for example, 10
To 1000 μm, preferably 100 to 500 μm
Is.

When the metal layer 101 is bonded to the substrate 21,
It is preferable that minute protrusions or dents are formed on the bonding surface of the substrate 21 with the metal layer 101. The minute protrusions or depressions are usually made of the same material as the substrate. The height or depth of the minute protrusions or depressions is not particularly limited, but is, for example, 10 nm or more and 100 nm or more.
μm or less. The pitch of the minute protrusions or depressions is also not particularly limited, but is, for example, 10n.
m or more and 100 μm or less.

The minute protrusions or depressions can be formed by the following method when, for example, silicon is used as the substrate. First, an organic compound layer such as a polyfluoroethylene resin is formed on a silicon substrate, and the silicon substrate is dry-etched on the organic compound layer.
After dry etching for a certain period of time, the organic compound layer is formed again, and dry etching is further performed for a certain period of time. By repeating this operation, innumerable needle-shaped silicon protrusions are formed on the surface of the silicon substrate. The height of the needle-shaped protrusions can be controlled by the dry etching time and the number of operations. For example, when the etching time is 3 minutes and the number of operations is 10, the average protrusion height is 1.2 μm.
m needle-like protrusions can be formed. The thickness of the organic compound layer may be appropriate, but may be about 50 nm, for example.

Here, as the dry etching, it is preferable to adopt reactive ion etching (RIE). In this case, as the etching gas, for example, a fluorine-based gas, a mixed gas of a fluorine-based gas mixed with O ₂ or the like can be appropriately selected depending on the film quality.
Examples of the fluorine-based gas include CHF ₃ , CH ₂ F ₂ ,
_{CH 3 F, CF 4, C} 2 F 6, C 2 F 4, C 3 F 8, C 4 , etc. F ₈ and the like.

When a glass substrate is used, the same fine needle-like irregularities can be obtained by changing the gas used in dry etching to a gas such as SF ₆ , BCl ₃ or Cl ₂ .

On the other hand, when a glass substrate is used, the etching gas for dry etching is SF ₆ , BC.
l _3, the gas ₂ such as Cl, hydrofluoric acid etching solution in wet etching (HF), buffered hydrofluoric acid (B
If it is changed to HF) or the like, it is possible to form the minute protrusions or the depressions by the same method as that for the silicon substrate.

The metal layer 101 is formed on the surface of the substrate 21 on which the fine protrusions or depressions are formed as described above. As a method of forming this metal layer 101, for example, a plating method can be adopted. . As the plating method, the above-mentioned electroless plating method similar to the formation of the reflection film of the waveguide can be adopted. That is, it is possible to form an oxide film on the substrate surface by a method such as thermal oxidation, perform surface treatment, and then form a metal layer by electroless plating. Alternatively, after forming the underlayer by electroless plating, a metal film may be grown to cover the underlayer by electrolytic plating. In this case, for example, a method of forming a NiP film as a base layer and forming Ni, Cu or the like by electrolytic plating can be adopted.

As described above, by adopting the electroless plating, it is possible to form a very uniform metal layer on the surface of the substrate on which fine irregularities are formed. This is because the film formed by electroless plating is chemically bonded to the substrate surface. The combination of this chemical bonding and the physical bonding by the anchor effect between the fine irregularities of the substrate can firmly bond the substrate and the metal layer.

Note that an electrolytic plating method may be used for forming the metal layer. In this case, the bonding between the substrate and the metal layer is only the bonding by the anchor effect, but by appropriately selecting the height, the depth, the pitch, the shape, etc. of the minute protrusions of the substrate, the strong bonding Is obtained.

As shown in FIG. 1, an optical communication component is constructed by combining the coupling section 2 and the optical circuit section 1.
At this time, one end of the waveguide formed in the optical circuit unit 1 is arranged so as to face the optical coupling component of the coupling unit 2. Figure 1
In the example shown in, the optical circuit unit 1 and the coupling unit 2 are the optical circuit element 28 (diffraction grating) formed on the first-stage substrate 21.
It is arranged so that the entrance port to the coupling lens 15 faces the coupling lens 15 (see FIG. 4). Accordingly, the optical circuit unit 1 can be optically coupled to the optical fiber 14 via the coupling lens 15, and further optically coupled to the external optical path via the optical fiber.

In FIG. 1, the first-stage substrate 2
Although the configuration in which the coupling portion 11 which is manufactured as a separate body is mounted on the above-mentioned 1 is shown, the present invention is not limited to this. For example, a mounting groove or the like may be formed on the surface of the first stage substrate, and an optical coupling component such as an optical fiber may be directly mounted on the first stage substrate.

In the above description, the form in which the optical circuit section is composed of the three-layer substrate has been illustrated, but the present invention is not limited to this. The optical circuit section may be composed of only a single-layer substrate or may be composed of four or more layers of substrates.

Further, in the above description, the electric wiring is formed on the surface of the substrate forming the optical circuit section, and the photoelectric conversion element and the electronic component are wired by the electric wiring.
The present invention is not limited to such a form. For example, when the reflective film formed in the waveguide is made of a conductive material such as a metal film, this reflective film can be used as an electric wiring.

In the above description, the optical circuit section is
Although the case where the photoelectric conversion element and the electronic component are mounted is illustrated, the present invention is not limited to this. For example,
It is also possible to mount an optical component on the third stage substrate instead of the photoelectric conversion element and the electronic component. FIG.
Shows an example of the optical communication component of such a form. FIG.
In the example shown in (1), an optical fiber 14 and a microlens array having lens convex surfaces 103 formed on both surfaces of the transparent plate 102 are mounted as optical components. With this configuration, the optical communication component can be used as an optical-optical coupling element. The method of mounting the optical component on the third-stage substrate can be performed in the same manner as the method of mounting the optical coupling component in the coupling portion as described above. It is also possible to adopt the methods described below as the second to fourth embodiments.

(Second Embodiment) In the first embodiment,
The case where the optical coupling component is fixed to the support by the adhesive at the coupling portion is illustrated. However, since it can be more firmly fixed, it is preferable to fix it by metal bonding such as solder. Hereinafter, such a form will be described.

Also in this embodiment, as in the first embodiment, the mounting groove and the bonding groove are formed in the support member that constitutes the coupling portion. In this embodiment, silicon is preferably used as the support, but plastic, glass, etc. are also applicable.

Further, a metal film is formed on at least a portion of the mounting groove which is in contact with the optical coupling component. This metal film is preferably formed not only on the mounting groove but also on the wall surface of the bonding groove. Examples of the metal include Au, Ag, Ni and Cu, and Au is particularly preferable because it has excellent corrosion resistance. As a method for forming the metal film, plating can be adopted, and in particular, electroless plating is preferably used because the film can be uniformly formed even in every corner of the groove.

An example of a method of forming a metal film by electroless plating will be described. First, before performing plating,
The substrate is pretreated. As the pretreatment, for example, when a layer containing Ni is formed by electroless plating, the support is immersed in a solution containing Pd catalyst nuclei and the Pd catalyst nuclei are attached to the surface thereof. Then, the support is immersed in an electroless plating bath. To give an example of this step, first, treatment with an electroless nickel (Ni) plating bath,
A NiP layer is formed. Then, this is treated with a substitution type electroless gold (Au) plating bath. As a result, part of Ni in the NiP layer is replaced with Au, and the Au layer is formed on the surface of the NiP layer. By this operation, a metal film made of NiP / Au can be formed.

Further, a metal film is also formed on the surface (that is, the side surface) of the optical coupling component that is bonded to the support. As the metal, the same metal as described above can be used. Also,
As a method for forming the metal film, various known methods can be adopted, but it is preferable to use plating.
It is particularly preferable to use electroless plating. Further, it is preferable that the formation of the metal film on the optical coupling component is performed before the metal film is arranged in the mounting groove of the support.

The formation of the metal film on the side surface of the optical coupling component can be carried out by the same method as the metal film on the support. However, since the optical coupling component needs to transmit light from the incident surface to the emission surface, the metal film needs to be formed only on the surface except the incident surface and the emission surface, that is, the side surface. As described above, as a method of forming the metal film only on the side surface of the optical coupling component, the following method can be adopted.

First, the incident surface and the emission surface of the optical coupling component are coated with carbon or fluorinated carbon to reduce the surface energy of the incident surface and the emission surface. The coating with carbon can be performed, for example, by sputtering carbon. The coating with fluorinated carbon can be carried out by plasma treatment with a fluorine-containing gas such as CF ₄ or C ₂ F ₆ .

Next, this optical coupling part is subjected to electroless plating. About this process, electroless nickel (Ni) plating and electroless gold (Au) plating are applied to form NiP / A.
The case of forming the u layer will be described as an example. Electroless Ni
In order to cause the plating reaction, it is necessary to attach Pd catalyst nuclei to the surface of the optical coupling component. As described above, the entrance surface and the exit surface of the optical coupling component are coated with carbon or fluorinated carbon, and the surface energy is reduced. Therefore, in the step of immersing the optical coupling component in the solution of the Pd catalytic nucleus, the Pd catalytic nucleus does not adhere to the incident surface and the emitting surface of the optical coupling component, but the Pd catalytic nucleus adheres only to the side surface. After this step, when the optical coupling component is immersed in the electroless Ni plating bath, the NiP layer is formed only on the side surface of the optical coupling component. Then, the optical coupling part is immersed in the substitution type electroless Au plating bath. In this substitution type electroless Au plating, N
The Au layer is formed by substituting Au for Ni in the iP layer. Therefore, Au is plated only on the side surface on which the NiP layer is formed. By this series of operations, the NiP / Au layer can be formed only on the side surface of the optical coupling component.

As described above, in this embodiment,
The mounting of the optical coupling component on the support is performed by soldering. Since the metal film is formed on each of the contact surfaces of the optical coupling component and the support, connection by soldering is possible. Bonding with solder provides higher bonding strength than bonding with resin or the like, so that the optical coupling component can be more firmly fixed onto the support.

In the above description, the bonding by solder has been described, but similarly, the optical coupling component can be firmly fixed on the support body by other metal joining such as metal welding. .

Further, in the above description, as in the first embodiment, the groove for the adhesive is provided in the support, but in this embodiment, the groove for the adhesive is not particularly required to be provided.

(Third Embodiment) In the second embodiment,
The case where the optical coupling component is fixed to the support by metal bonding in order to realize strong adhesion at the coupling portion is illustrated. However, by applying a treatment with a silane coupling agent to at least one of the optical coupling component and the support, firm adhesion can be realized with an adhesive. According to such a form, it becomes possible to firmly bond and fix the optical coupling component and the support without forming a metal film. Hereinafter, such a form will be described.

In the present embodiment, first, a silane coupling agent is attached to at least a portion of the mounting groove of the support which is in contact with the optical coupling component. Further, the silane coupling agent is also attached to the adhesive surface (that is, the side surface) of the optical coupling component with the support. After that, the both are fixed and bonded with an adhesive such as an ultraviolet curable resin.

At this time, the silane coupling agent to be used is once hydrolyzed, and the hydrolyzed silane coupling agent is adhered to at least the side surface of the optical coupling component and the mounting groove of the support, and then both of them are attached. It is preferable to fix and adhere with an adhesive such as an ultraviolet curable resin. More preferably, it is preferable that after the hydrolyzed silane coupling agent is attached, the optical coupling component and the support are subjected to heat treatment, and then both are fixedly adhered with an ultraviolet curable resin. The heat treatment temperature is, for example, 120 ° C. or higher, preferably 120 to 200 ° C., more preferably 12
It is 0 to 150 ° C.

In the above description, the case where the treatment with the silane coupling agent is applied to both the support and the optical coupling component has been exemplified. However, this treatment is applied to either the support or the optical coupling component. It may be applied only to.

In this embodiment, as in the first embodiment, the support may be provided with an adhesive groove.
In particular, it is not necessary to provide an adhesive groove.

(Fourth Embodiment) In this embodiment, a mode in which a microlens or a microlens array is used as the coupling lens of the coupling section will be described.

The microlens has a structure in which a pair of lens convex surfaces is provided on both surfaces of a transparent plate. The microlens array has a structure in which a plurality of pairs of the lens convex surfaces are provided. The transparent plate and the convex surface of the lens are preferably made of the same material, and are preferably integrally molded.

Such a microlens (array) is
By forming a pair of lens surfaces on both sides of the transparent plate,
It has an advantage that optical axis alignment becomes easy. Also,
If the same material as the support is used as the microlens (array), the expansion coefficient of the lens and the bench can be made the same, so that the accuracy of optical axis alignment is further improved.

As the microlens (array),
Silicon is preferably used. Since silicon has a high refractive index, the curvature of the lens can be reduced, the aberration can be reduced, and the focal spot diameter can be reduced. Therefore, it has an advantage that it can be made compact. Moreover, it is easy to form a planar array, and a plurality of lens convex surfaces can be collectively molded by a method such as dry etching. Further, even when an antireflection film or the like is formed on each lens convex surface, by performing this film forming process on the entire transparent plate, it is possible to collectively form a film on a plurality of lens convex surfaces.

When the silicon microlens (array) is arranged on the support, it can be directly fixed to the support without using an adhesive or the like.

13 and 14 are plan views for explaining such a fixing method. First, as shown in FIG. 13, the support 11 is anisotropically etched to form a trapezoidal groove 16. Then, a groove (fixing groove) 17 perpendicular to the surface of the support is formed by dicing. In the figure, 12 is a mounting groove for mounting an optical fiber, and 14 is an optical fiber fixed in the mounting groove. After that, as shown in FIG. 14, a microlens array having lens convex surfaces 103 integrally formed on both surfaces of the transparent plate 102 is inserted into the fixing groove 17 and fixed. Figure 15
[FIG. 3] is a cross-sectional view showing a state in which the microlens array is fixed to a support. This allows the microlens array to be easily fixed to the support.

The mounting of the microlens (array) on the support is not limited to the above method, and it is also possible to mount it by metal bonding such as solder or bonding using an adhesive.

When metal bonding such as soldering is adopted, a metal film is formed on a portion of the microlens (array) which is bonded to the support (the portion other than the convex surface of the lens), and the fixing groove of the support is formed. A metal film may be formed on the wall surface of and the both may be joined by soldering or the like. The method of forming the metal film on the microlens (array) can be carried out in the same manner as the method described in the second embodiment.

When an adhesive is used, at least one of the adhesion portion of the microlens (array) to the support (the portion other than the convex surface of the lens) and the wall surface of the fixing groove of the support are used. After attaching the silane coupling agent, it is preferable to adhere the both. The treatment with the silane coupling agent can be performed in the same manner as the method described in the third embodiment.

(Fifth Embodiment) Next, a preferred mode of the optical communication module of the present invention will be described. This optical communication module is composed of a laminate in which a plurality of substrates are directly adhered and laminated, and at least one of a horizontal waveguide and a vertical waveguide is formed on each substrate. The waveguides formed on the respective substrates are optically coupled by a light bending portion provided with a reflecting mirror. As a result, the waveguides formed on each substrate are connected to each other to form a three-dimensionally extended three-dimensional optical path.

More specifically, this optical communication module is
At least the first substrate and the second substrate are in direct contact and laminated. The first substrate has a horizontal waveguide therein, a light bending portion provided at an end portion of the horizontal waveguide and having a reflecting mirror for bending the light path substantially vertically, and a portion extending in the thickness direction following the light bending portion. A first vertical waveguide portion continuing to the surface is formed by the cavity. The second substrate is laminated on the first substrate, and at a position facing the exposed portion of the first vertical waveguide portion on the substrate surface, the second substrate continues inward in the thickness direction from the surface. The vertical waveguide portion of is formed by a cavity. A vertical optical path is formed inside the stacked body composed of the first substrate and the second substrate by a cavity penetrating in the thickness direction from the inside of the first substrate to the inside of the second substrate. .

Although the optical communication module may be composed of a first substrate and a second substrate, at least one other substrate may be replaced with the first substrate or the second substrate. It may be provided on the outside. That is, when the optical communication module is composed of a laminated body of three or more substrates, one of the adjacent substrates may satisfy the above requirement.

An example of this optical communication module is one having a structure substantially similar to that of the optical circuit section in the first embodiment described above. The detailed description thereof is the same as that of the optical circuit unit according to the first embodiment, and will be omitted.

A plurality of such optical communication modules are optically coupled to each other to form an optical communication component. The coupling between the optical communication modules is not particularly limited, but a method of laminating the modules may be used. In this case, the stacking of the modules can be performed in the same manner as the method exemplified as the method of joining the substrates of the optical circuit section in the first embodiment. Further, a plurality of modules may be formed in the same laminated substrate and they may be coupled by a waveguide or the like formed in the laminated substrate.
It is also possible to couple the modules together via an optical coupling component such as an optical fiber.

(Sixth Embodiment) Next, the components constituting the optical communication component or the optical communication module of the present invention, or
Components used in combination with the optical communication component or the optical communication module of the present invention will be exemplified. Incidentally, it goes without saying that these components can also be used alone independently of the optical communication component or the optical communication module of the present invention.

(1) An optical communication component in which a metal layer is bonded to at least one surface of a substrate, and minute projections or depressions of the substrate material are formed at the interface between the bonding surface of the substrate and the metal layer. Optical communication parts characterized by. According to this optical communication component, it is possible to efficiently dissipate the heat accumulated in the substrate and prevent the substrate from being cracked or distorted.

(2) An optical communication component precursor whose optical waveguide end face is covered with carbon or fluorinated carbon. This precursor is treated with an electroless nickel (Ni) plating bath and an electroless gold (Au) plating bath to provide an optical communication component in which only the incident surface and the emitting surface of the optical communication component are plated with NiP / Au. . Also, an optical communication component in which this optical communication component is adhered and fixed to an optical bench on which a metal film is formed.

[0155]

EXAMPLES Hereinafter, a method of fixing the support (optical bench) and the optical coupling component to each other by metal bonding at the coupling portion as described in the second embodiment will be described with reference to experimental examples. However, these experimental examples are merely examples and do not limit the present invention.

(Experimental Example 1) A carbon film was formed to a thickness of 10 nm on the end face of a glass optical lens having an outer diameter of 1 mm and a length of 2 mm by a sputtering method. Then, the glass optical lens was immersed in the electroless Ni plating bath. By this operation, NiP was plated only on the side surface of the glass optical lens.
Subsequently, the glass optical lens was immersed in a substitution type electroless Au plating bath to plate Au on NiP. Anisotropic etching was applied to a (100) -plane Si wafer having a thickness of 1.5 mm to form a trapezoidal groove having a width of 1000 μm, a depth of 500 μm and a length of 5 mm. Then, a silicon optical bench (hereinafter referred to as "SiOB") was immersed in an electroless Ni plating bath. By this operation, N
iP was plated. Subsequently, SiOB was immersed in a substitution-type electroless Au plating bath to perform Au plating on NiP. Then, a glass optical lens metallized with NiP / Au was placed on the SiOB, and both were adhesively fixed with solder.

(Experimental Example 2) The side surface of the glass optical lens was the same as in Example 1 except that the end surface of the glass optical lens having an outer diameter of 1 mm and a length of 2 mm was treated with CF ₄ gas plasma. Only plated. In the same manner as in Example 1, after plating the SiOB surface with NiP / Au,
An optical lens made of glass, which was metallized with NiP / Au, was placed on B, and both were adhesively fixed by soldering.

(Comparative Experimental Example 1) With a thickness of 1.5 mm (10
Anisotropic etching with KOH is applied to the 0) surface Si wafer, and the width is 1000 μm, the depth is 500 μm, and the length is 5 mm.
Trapezoidal grooves were formed. A glass optical lens with an outer diameter of 1 mm and a length of 2 mm is placed on this SiOB, and the wavelength is 365 nm.
UV rays were radiated, and both were adhered with an ultraviolet curable resin.

The samples obtained by adhering and fixing the glass optical lens to the trapezoidal groove of SiOB obtained in Experimental Examples 1 and 2 and Comparative Experimental Example 1 were stored in an environment of 85 ° C. and 90% RH for 1 week. In Experimental Examples 1 and 2, the glass optical lens was not detached, but in the sample of Comparative Experimental Example 1, the glass optical lens was detached from the trapezoidal groove of SiOB.

The samples in which glass optical lenses were bonded and fixed to the trapezoidal grooves of SiOB obtained in Experimental Examples 1 and 2 and Comparative Experimental Example 1 were heated at 85 ° C. (2 hours) /-40 ° C. (2 hours). The cycle test was performed 10 times. In Experimental Examples 1 and 2, the glass optical lens was not detached, but in the sample of Comparative Experimental Example 1, the glass optical lens was detached from the trapezoidal groove of SiOB.

[0161]

As described above, according to the optical communication component of the present invention, it has a substrate and a waveguide formed inside the substrate, and at least one end of the waveguide is optically connected to the external optical path. In the optical communication component that can be electrically coupled, the waveguide includes a cavity formed inside the substrate and a reflective film that covers a wall surface of the cavity, and transmits light in the cavity. Therefore, the light transmission rate of light in the waveguide is high. Further, according to the optical communication component, the optical path can be sharply bent, so that the component can be downsized.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an example of an optical communication component according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is an external perspective view showing an example of a mounting groove and an adhesive groove in the coupling portion of the optical communication component.

FIG. 4 is an external perspective view of a first-stage substrate that constitutes an optical circuit unit of the optical communication component.

FIG. 5 is a partially enlarged view showing a portion of the first stage substrate on which a waveguide and a diffraction grating are formed.

6 is a cross-sectional view taken along the line A-A ′ of FIG.

7 is a cross-sectional view taken along the line B-B ′ of FIG.

FIG. 8 is a plan view showing an optical bending portion of a waveguide formed on the first-stage substrate.

FIG. 9 is an external perspective view of a second stage substrate that constitutes an optical circuit unit of the optical communication component.

10 is a cross-sectional view taken along the line A-A ′ of FIG.

11 is a sectional view taken along the line B-B ′ of FIG. 9.

12 is a cross-sectional view taken along the line C-C ′ of FIG.

FIG. 13 is a plan view showing another example of a support body that constitutes a coupling portion of the optical communication component.

FIG. 14 is a plan view showing another example of the coupling portion of the optical communication component, showing a state where an optical fiber and a microlens array are fixed to the support.

15 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 16 is an external perspective view showing another example of the optical communication component of the present invention.

[Explanation of symbols]

1 Optical circuit section 2 connection 11 Support 12 mounting groove 13 Adhesive groove 14 optical fiber 15 coupling lens 16 trapezoidal groove 17 Fixing groove 21 First Stage Substrate 26 Horizontal Waveguide 27 Metal film 28 diffraction grating 29 Light bend 31 Second stage substrate 32 horizontal waveguide 33 Metal film 34 Light bend 41 Third Stage Substrate 42 Vertical Waveguide 43 Metal film 51 Photodiode (PD) 52 wiring pattern 53 LSI 101 metal plate

Continued front page    (72) Inventor Tetsuhiko Sanbe             Hitachi Ma, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. (72) Inventor Akihito Sakamoto             Hitachi Ma, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. F-term (reference) 2H037 AA01 BA23 CA34 CA37 DA04                       DA12                 2H047 KA03 KA12 LA09 LA19 MA05                       MA07 PA01 PA21 PA24 QA04                       TA01 TA36                 5F088 AA01 BA15 BB01 JA03 JA12                       JA14

Claims (18)

[Claims] 1. An optical communication component comprising a substrate and a waveguide formed inside the substrate, wherein at least one end of the waveguide is optically coupled to an external optical path, wherein the waveguide is An optical communication component comprising: a cavity formed inside the substrate; and a reflective film covering a wall surface of the cavity, for transmitting light in the cavity. 2. A first substrate having grooves formed on the surface of the substrate.
And a second substrate that is closely laminated on the surface of the first substrate on which the groove is formed, wherein the cavity of the waveguide is formed by the groove. 1. The optical communication component according to 1. 3. The waveguide has a light bending portion for changing a light transmission direction, and in the light bending portion, a cavity wall surface of the waveguide is inclined with respect to the light transmission direction. 1. The optical communication component according to 1. 4. An optical circuit element optically coupled to one end of the waveguide, wherein one end of the waveguide can be optically coupled to the external optical path via the optical circuit element. The optical communication component according to claim 1. 5. The photoelectric conversion element further includes a photoelectric conversion element optically coupled to one end of the waveguide, and an electric wiring formed on the surface of the substrate, wherein the photoelectric conversion element includes the electric wiring via the electric wiring. The optical communication component according to claim 1, which can be electrically connected to an external electric circuit. 6. The optical communication component according to claim 1, wherein the cavity is filled with a light transmissive medium. 7. The optical communication component according to claim 6, wherein the light transmissive medium is a photocurable resin. 8. The reflection film is made of a metal film.
Optical communication parts described. 9. A support body having a groove formed therein for mounting an optical fiber is provided, and the support body is arranged such that one end of the groove and one end of the waveguide face each other, The optical communication component according to claim 1, wherein the waveguide is optically coupled to the optical fiber when the optical fiber is mounted in the groove. 10. A metal film is formed on a wall surface of the groove for mounting the optical fiber of the support.
Optical communication parts described. 11. A coupling lens is mounted on the support so as to be located between one end of the groove and one end of the waveguide, and when an optical fiber is mounted in the groove. 10. The optical communication component according to claim 9, wherein one end of the waveguide is optically coupled to the optical fiber via the coupling lens. 12. A metal film is formed on a portion of the support where the coupling lens is arranged, a metal film is formed on a side surface of the coupling lens, and the both are metal-bonded to each other. Optical communication parts. 13. A substrate, formed inside the substrate,
A vertical waveguide that transmits light in the thickness direction of the substrate; a horizontal waveguide that is formed inside the substrate and that transmits light in the in-plane direction of the substrate; and the vertical waveguide and the horizontal waveguide. An optically bent portion that is optically coupled to each other, wherein the substrate has a groove formed on a surface thereof, and a first substrate having a reflecting mirror arranged at at least one end of the groove, and the groove of the first substrate. And a second substrate that is laminated in close contact with the formed surface and that has a through hole that communicates with a portion of the groove in which the reflecting mirror is arranged, the horizontal waveguide being formed by the groove. The formed cavity,
A reflection film covering the wall surface of the cavity, transmitting light in the cavity, wherein the vertical waveguide forms a cavity formed by the through hole, and a reflection film covering the wall surface of the cavity. And transmitting light in the cavity, wherein the light bending portion includes the reflecting mirror, and the light is transmitted in the in-plane direction from the thickness direction of the substrate by reflection on the reflecting mirror surface. Direction, or from the in-plane direction of the substrate to the thickness direction, a laminated optical communication module. 14. The stacked optical communication module according to claim 13, further comprising an optical circuit element optically coupled to at least one of the horizontal waveguide and the vertical waveguide in the substrate. 15. A photoelectric conversion element optically coupled to one end of the waveguide, and an electric wiring formed on the surface of the substrate, wherein the photoelectric conversion element includes the electric wiring via the electric wiring. The stacked optical communication module according to claim 13, which can be electrically connected to an external electric circuit. 16. The stacked optical communication module according to claim 13, wherein the reflecting film and the reflecting mirror are made of a metal film. 17. The stacked optical communication module according to claim 13, wherein a cavity forming the vertical waveguide and the horizontal waveguide is filled with a light transmissive medium. 18. An optical communication component comprising a plurality of optical communication modules optically coupled to each other, wherein at least one of the optical communication modules is a stacked optical communication module according to claim 13. .