JPH0638490B2 - Hybrid optical integrated circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention provides easy connection between a fiber, an optical semiconductor element, etc. and an optical waveguide, which is necessary for optical communication and optical information processing, and has a single mode. The present invention relates to a hybrid optical integrated circuit suitable for application to a system.

"Prior Art" A hybrid optical integrated circuit in which an optical waveguide, an optical fiber, a filter, a light emitting / receiving element, etc. are combined and integrated on the same substrate.
It is expected as a means for realizing optical circuits for optical communication such as optical multiplexer / demultiplexers and optical switches, and optical information processing. However, this field is still in the basic research stage, and almost no optical circuit that has been put to practical use has been found so far.

By the way, as a hybrid optical integrated circuit of this kind, a technique using a silica-based optical waveguide has been recently proposed and a basic study has been made [eg, Japanese Patent Application No. 59-167677 and M.S. Kawaclin et al, Electron Lett. 21,314, (198
Four)〕. FIG. 1 shows an example of a hybrid optical integrated circuit for which these basic studies have been made. 1 is a substrate, 2 is a channel optical waveguide, 3 is a fiber guide, 4 is an optical fiber, 5
Is a filter guide, 6 is a minute reflecting mirror guide, 7 is a semiconductor laser guide, 8 is a semiconductor laser, 9 is a minute reflecting mirror, 1
Reference numeral 0 is an avalanche photodiode, 11 is an interference film filter, and a channel optical waveguide 2 is provided on the same substrate 1 for composite integration of the optical waveguide and the optical fiber receiving / emitting element.
And various guides 3, 5, 6, 7 are integrated. In this circuit, the alignment with the optical waveguide 2 is completed only by inserting the various elements into the guides 3, 5, 6, 7 and therefore the waveguide 2 and the guides 3, 5 are arranged. ，
The height of 6 and 7 is required to be about 70 to 100 μm. Conventionally, this kind of optical circuit has been applied to a multi-mode component, so that the waveguide width is about 40 to 50 μm.
Therefore, the aspect ratio (height / width) of the waveguide is 1.
It is about 5 to 2, and the structure has no problem in strength.

"Problems to be solved by the invention" However, when this circuit is applied to a single mode system component,
Since the width of the waveguide is about 5 to 10 μm, the aspect ratio of the waveguide is about 10. Such thin and tall patterns are strongly unstable, which leads to fiber,
When the semiconductor laser or the like is mounted, the waveguide may be chipped. Further, the single-mode optical waveguide is required to have a processing accuracy that is one digit higher than that of the multi-mode optical waveguide. From this viewpoint, it is not preferable to set the waveguide portion to a height of 70 to 100 μm.

On the contrary, if the height of the guide is reduced to 10 to 20 μm, which is considered to be no problem as the height of the single mode system waveguide, the function of the guide cannot be sufficiently exhibited. That is, when using such a short guide to connect an optical fiber, for example, the optical fiber outer diameter must be about 30 μm, but such a thin fiber is inconvenient to handle.

As described above, in the conventional structure, it is difficult to manufacture both the single mode optical waveguide and the guide in a compatible manner.

An object of the present invention is to solve the problem that, when the conventional guided optical waveguide circuit is applied to a single mode system, it is difficult to set the height of the waveguide and the height of the guide at the same time,
It is to provide a hybrid optical integrated circuit suitable for a single mode system.

"Means for Solving Problems" One of the present invention is to form a step on a substrate on which a fiber guide or an optical element guide and an optical waveguide are provided, and to arrange the optical waveguide on the upper surface of the upper substrate and on the upper surface of the lower substrate. A fiber guide or an optical element guide is provided.

Another aspect of the present invention is a hybrid optical integrated circuit including at least one of a fiber guide and an optical element guide provided on a substrate, and an optical waveguide formed in a convex shape on the substrate, wherein the substrate is provided. A step is formed, an optical waveguide is formed on the upper surface of the upper substrate, and at least one of a fiber guide and an optical element guide and an optical semiconductor element are provided on the upper surface of the lower substrate, and at least one of the upper and lower substrates is electrically connected. A wiring supporting base is formed, a first conductive film is formed on the upper surface of the lower substrate, and a second conductive film is formed on the upper surface of the electric wiring supporting base.
The conductive films are formed so as to be insulated from each other, and the first conductive film and the second conductive film are connected to the optical semiconductor element to enable power supply.

Further, in the present invention, the lower substrate may be a Si substrate, and the lower substrate and the upper substrate may be Si substrates. Furthermore, the optical waveguide, each guide, and the electric wiring support may be formed of a silica optical waveguide film.

[Working] By forming a step on the substrate, providing each guide in the lower stage and forming the optical waveguide in the upper stage, it is possible to form the guide with a high height while forming the optical waveguide with a low height.

[Embodiment] FIG. 1 is an optical multiplexing / demultiplexing module showing an embodiment of the present invention, in which 1a indicates a lower substrate (Si substrate), and a quartz system is formed on the central portion of the upper surface of the lower substrate 1a. An upper substrate 1b made of an optical waveguide film is formed, and a lower substrate 1a and an upper substrate 1 are formed.
The substrate 1 having a step is formed by b and. On the upper surface of the upper substrate 1b, a silica-based channel optical waveguide 2 is provided from one side to the other side of the upper surface, and the upper substrate 1b is further provided.
Filter guides 5, 5 are formed at the center of the upper surface of the optical waveguide 2 so as to sandwich the central portion in the length direction of the optical waveguide 2. The channel optical waveguide 2 has a cladding layer 2a and a core layer 2b.
It consists of Further, on one side (left side in FIG. 1) of the upper substrate 1b, on the side of the end, and on the upper surface of the lower substrate 1a,
The fiber guides 3 and 3 are provided upright, and on the other side of the upper substrate 1b (on the right side in FIG. 2), on the upper side of the lower substrate 1a, at the upper surface of the lower substrate 1a, one end of the optical waveguide 2 is sandwiched. Guides 6, 6
And a minute reflecting mirror 9 is erected on the upper surface of the lower substrate 1a between the reflecting mirror guides 6 and 6. In addition,
The optical waveguide 2 is branched laterally at its central portion, and a light emitting element guide 7 and a semiconductor laser 8 are provided upright on the upper surface of the lower substrate 1a in front of the tip of the branched portion. On the other hand, inserted between the guides 3 and 3 is an optical fiber composed of a fiber cladding layer 4a and a fiber core portion 4b. A quartz optical waveguide film is etched on the outer surface of each of the guides 3, 5, 6, and 7.

For the optical multiplexing / demultiplexing module configured as described above,
Since the channel optical waveguide 2 is formed on the upper substrate 1b, its back can be made thinner by the thickness of the upper substrate 1b than that of the conventional structure. Even if the channel optical waveguide 2 is a single mode system, the The ratio can be reduced. In addition, the guides 3, 5, 6, 7 are provided on the lower substrate 1a.
The guides 3, 5, 6 and 7 are formed to have a necessary and sufficient height so that the guides 3, 5, 6 and 7 are erected on the upper surface and have a height obtained by adding the height of the channel optical waveguide 2 to the thickness of the upper substrate 1b. be able to. As a result, for example, when this optical multiplexing / demultiplexing module is manufactured by using a single mode optical waveguide, the aspect ratio of the channel optical waveguide 2 can be reduced to about 1 to 3 and the mechanical reliability is improved. Becomes higher. On the other hand, since a sufficient depth (height) can be secured in the portion of the guide 3, it is possible to exhibit the functions of fiber positioning, semiconductor laser positioning, and the like.

Next, the design conditions of the above-described guided optical waveguide circuit will be described with reference to specific numerical examples. FIG. 2 shows the waveguide 2 from the outside of the guide 3 in the vicinity of the fiber guide 3 of FIG.
It is the figure which looked at the side. In the figure, l ₁ represents the height from the upper surface of the lower substrate 1a to the center of the core layer 2b of the waveguide, and l ₂
Is the height from the upper surface of the lower substrate 1a to the upper part of the cladding layer of the waveguide 2, which is equal to the height of the guide 3. l ₃ is the height from the upper surface 1b of the upper substrate to the upper part of the cladding layer 2a of the waveguide 2, which is equal to the height of the waveguide 2.
Here, the width of the waveguide is set to w and the fiber guide 3,
The interval of 3 is set to 2l ₁ . Therefore, if the outer diameter of the fiber 4 is set to 2l ₁ , the fiber core portion 4b can be simply inserted by inserting the fiber 4 into the fiber guide 3.
And the core layer 2b of the waveguide 2 can be aligned with each other. For example, the fiber 4 has an outer diameter of 125 μm and a core diameter of 8 μm.
Think of the fiber. At this time, the guide interval 2l ₁ is 1
It is necessary to set it to 25 μm, so that l ₁ = 6
2.5 μm. On the other hand, the core size of the waveguide 2 is set to the core layer width (w) = core layer height = 8 μm according to the fiber. In accordance therewith, the height l ₃ of the waveguide 2 including the cladding layer 2a is, for example, l ₃ = 15 μm, and the fiber guide height l ₂ is, for example, l ₂ = 74 μm. By setting like this numerical example, the aspect ratio of the waveguide 2 can be reduced to about 2. On the other hand, the fiber guide 3 may have a sufficient height of about 60 μm. In accordance with this, as shown in FIG. 3, the semiconductor laser 8 has its substrate thickness adjusted by polishing or the like so that the height of the active layer 8 a is higher than the upper surface of the lower substrate 1 by l ₁ . It should be just like that. In mounting the light receiving element, the height of the micro-reflecting mirror 9 is set to the micro-reflecting mirror guide 6
The height may be set to l ₂ which is equal to the height, and the light receiving element 10 such as an avalanche photodiode may be installed thereon as shown by the arrow in FIG. If the interference film filter chip 11 is inserted into the filter guide 5 as shown by the arrow in FIG. 1, the optical multiplexing / demultiplexing module can be assembled. As described above, according to this configuration, the aspect ratio of the single-mode optical waveguide can be suppressed to about 2 and a guide having a depth of 60 μm or more can be formed. Therefore, the present invention can be applied to a single-mode hybrid optical integrated circuit.

In addition, an electric wiring support for the optical element may be formed. FIG. 4 shows a semiconductor laser 8 and an electric wiring support 12
It is a figure which shows the example made into the structure which can provide electric power by providing.

In the structure shown in FIG. 4, an electric wiring support 12 penetrating the upper substrate 1b is provided on a corner of the upper substrate 1b adjacent to the semiconductor laser 8 on the upper surface of the lower substrate 1a. The configuration is substantially the same as that of the above embodiment. In this example, the metal film 13 is formed as a conductive film on the upper surface of the electric wiring support 12. In addition,
As the metal film 13, an Al / Au vapor deposition film or the like may be used. A metal film 13 'is also formed on the surface of the lower substrate 1a. The metal film 13 'on the surface of the lower substrate 1a is connected to the electrode of the semiconductor laser 8, and the metal film 13 on the upper surface of the electric wiring support 12 and the upper electrode 8 on the active layer 8 are connected.
Bonded with b by a gold wire 14. In this case, if the width of the electric wiring support base 12 is about the width of the single mode optical waveguide, by forming the electric wiring support base on the upper substrate 1b, the aspect ratio is small like the optical waveguide, It is possible to manufacture an electric wiring support having sufficient mechanical strength.

FIG. 5 shows another embodiment of the present invention, which is a lower substrate 1a.
Both the upper substrate 1b and the upper substrate 1b are made of a Si substrate, and the channel optical waveguide 2, the fiber guide 3 and the semiconductor laser guide 7 made of a quartz optical waveguide film are formed on the Si substrate. In this example, the conductive film 13 is formed on the semiconductor laser guide 7.
Is formed, and the laser guide 7 also serves as an electric wiring support base. A conductive film 13 'is also formed on the surface of the lower substrate 1a on which the guide 7 is formed. In this optical circuit, a fiber is inserted into a fiber guide 3, a semiconductor laser is attached to a laser guide 7, and conductive films 13 and 13 'are provided.
By using the electric wiring, it functions as a confluence module. Also in this embodiment, since the waveguide 3 is formed on the upper substrate 1b, its height is short,
Therefore, since the aspect ratio can be reduced, sufficient mechanical strength can be secured.

As described above, one hybrid optical integrated circuit of the present invention has a two-step structure of an upper substrate and a lower substrate with a step on the substrate surface, and a narrow single-mode optical waveguide is provided on the upper substrate. The components are formed on the lower substrate so that the height of the components is minimized, and components that do not function without a sufficient height, such as guides, are formed on the lower substrate. Even with the pattern, there is an advantage that the aspect ratio can be set to about 1 to 2 and the guide can sufficiently exhibit its function. Such an optical circuit is particularly effective for a single mode hybrid optical integrated circuit.

As described above, another hybrid optical integrated circuit of the present invention has a two-step structure of an upper substrate and a lower substrate with a step on the substrate surface. It is formed on the top of the substrate, and its height is kept to a minimum. In addition, components such as guides that do not function without sufficient height are formed on the lower substrate, so Even with a thin pattern, the aspect ratio can be set to about 1 to 2, and
The guide also has the advantage that it can exert its functions sufficiently. Such an optical circuit is particularly effective for a single mode hybrid optical integrated circuit. Further, by using the conductive film of the electric wiring support on the substrate and the conductive film of the substrate, electric wiring for the circuit of the optical semiconductor element formed on the substrate can be formed and power can be supplied.

[Brief description of drawings]

FIG. 1 shows a lower substrate S which is one embodiment of the present invention.
i, a perspective view of an optical multiplexing / demultiplexing module including an upper substrate and a silica-based optical waveguide film, FIG. 2 is a side view of a fiber guide portion of the module shown in FIG. 1, and FIG. 3 is a semiconductor laser of the module shown in FIG. FIG. 4 is a perspective view of a guide, and FIG. 4 is a perspective view of an optical circuit provided with an electric wiring support, which is another embodiment of the present invention.
FIG. 5 is another embodiment of the present invention, and is a perspective view of an optical circuit in which both the lower substrate and the upper substrate are made of Si. FIG. 6 is an example of a conventional guided optical waveguide circuit (optical multiplexing / demultiplexing module). FIG. 1 ... substrate, 1a ... lower substrate, 1b ... upper substrate, 2
...... Channel optical waveguide, 3 ...... Fiber guide, 4 ......
Optical fiber, 5 ... Filter guide, 6 ... Micro-reflector guide, 7 ... Light emitting element guide, 8 ... Semiconductor laser,
12 ... Electrical wiring support, 13, 13 '... conductive film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masao Kawachi Inventor Masao Kawachi 162 Shirahane, Shikata, Tokai-mura, Naka-gun, Ibaraki Prefecture Nippon Telegraph and Telephone Corporation, Ibaraki Telecommunications Research Institute (72) Morio Kobayashi Naka-gun, Ibaraki Prefecture Tokai-mura Large-sized Shirahoji 162 Shirane, Nippon Telegraph and Telephone Corporation, Ibaraki Telecommunications Research Laboratories (72) Inventor Hiroshi Terui Tokai-mura, Naka-gun, Ibaraki Prefecture Large-sized white Shirane Shirane, Nippon Telegraph and Telephone Corporation Ibaraki Telecommunications Co., Ltd. In the laboratory (56) References Japanese Patent Publication No. 5748 (JP, B2)

Claims (6)

[Claims] 1. A hybrid optical integrated circuit comprising at least one of a fiber guide and an optical element guide provided on a substrate, and an optical waveguide formed in a convex shape on the substrate, wherein a step is formed on the substrate. A hybrid optical integrated circuit in which an optical waveguide is formed on the upper surface of the upper substrate and at least one of a fiber guide and an optical element guide is provided on the upper surface of the lower substrate. 2. A hybrid optical integrated circuit comprising at least one of a fiber guide and an optical element guide provided on a substrate, and an optical waveguide formed in a convex shape on the substrate, wherein a step is formed on the substrate. , An optical waveguide is formed on the upper surface of the upper substrate, at least one of a fiber guide and an optical element guide and an optical semiconductor element are provided on the upper surface of the lower substrate, and an electric wiring support is provided on at least one of the upper and lower substrates. A first conductive film is formed on the upper surface of the lower substrate, and a second conductive film is formed on the upper surface of the electric wiring support in a mutually insulated state, and the first conductive film is formed on the optical semiconductor element. A hybrid optical integrated circuit capable of supplying power by connecting a second conductive film. 3. The hybrid optical integrated circuit according to claim 1, wherein the lower substrate is a Si substrate, and the upper substrate, the optical waveguide, each guide, and the electric wiring support are formed of a silica optical waveguide film. . 4. The hybrid optical integrated circuit according to claim 1, wherein the upper and lower substrates are both Si substrates, and the optical waveguide, each guide, and the electric wiring support are formed of a silica optical waveguide film. . 5. The hybrid optical integrated circuit according to claim 2, wherein the lower substrate is a Si substrate, and the upper substrate, the optical waveguide, each guide, and the electric wiring support are formed of a silica optical waveguide film. . 6. The hybrid optical integrated circuit according to claim 2, wherein the upper and lower substrates are both Si substrates, and the optical waveguide, each guide and the electric wiring support are formed of a silica optical waveguide film. .