JP3116979B2 - Optical coupling structure between optical waveguides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling structure between optical waveguides, and is useful for optically coupling optical waveguides formed on separate substrates in an optical communication device or the like. .

[0002]

2. Description of the Related Art In the prior art, an optical coupling structure for coupling optical waveguides formed on separate substrates is generally a method of directly coupling the end faces of the optical waveguide as shown in FIG. In the figure, 1 is the core of the first optical waveguide, 2 is the cladding layer of the first optical waveguide, 3 is the substrate on which the core 1 and the cladding layer 2 of the first optical waveguide are formed, and 4 is the second Reference numeral 5 denotes a core of the optical waveguide, 5 denotes a cladding layer of the second optical waveguide, and 6 denotes a substrate on which the core 4 and the cladding layer 5 of the second optical waveguide are formed.

[0003]

In the optical coupling structure between optical waveguides according to the prior art as described above, the core 1 of the first optical waveguide and the core 4 of the second optical waveguide are directly coupled with good coupling efficiency. For this purpose, it is necessary not only to align the end faces of the respective optical waveguides three-dimensionally but also to control the angles formed by the respective optical waveguides so that the optical axis directions coincide with each other. It is. As described above, in the conventional optical coupling structure, the optical coupling between the optical waveguides formed on different substrates requires high-precision alignment of three or more axes such as three-dimensional alignment and angle adjustment. There is the disadvantage that coupling is difficult. In addition, there is a problem that an optical signal from the first optical waveguide is reflected at the end face of the second optical waveguide and is easily affected by reflected return light.

In view of the above prior art, the present invention eliminates the need for high-precision alignment of three or more axes as described above, and eliminates the effects of reflected return light when end faces are directly coupled. It is an object of the present invention to provide an optical coupling structure between waveguides.

[0005]

To achieve the above object, the structure of the present invention comprises a first optical waveguide formed on a first substrate and a second optical waveguide formed on a second substrate. Between
Flexible and moreover an optical coupling structure for optically coupling through the third optical waveguide is a film structure, the third
The two end portions of the optical waveguide are both end surfaces of the first and second optical waveguides.
And the first and second optical waveguides and the third light
Third optical waveguide near the overlapped portion with the waveguide
On the surface, the first and second optical waveguides are made of the same material as the third optical waveguide.
A third optical waveguide opposing the end face of the optical waveguide,
Protrusions having the same width are provided, and the first and second protrusions have the same width.
Taper in the thickness direction on the side opposite to the side facing the optical waveguide
It has further at both ends of the third optical waveguide, moreover first及
And the portion corresponding to the overlapping portion with the second optical waveguide,
A projection made of a material equal to that of the third optical waveguide material;
The protrusion is a protrusion having a width equal to that of the third optical waveguide .

[0006]

According to the present invention having the above-described structure, the first and second optical waveguides are brought into contact with the third optical waveguide in the form of a film in contact with a part of the longitudinal surface of the first and second optical waveguides. By coupling the two optical waveguides, the flexibility of the film can be utilized, the first and second optical waveguides are aligned in the height direction, and the plane on which the first and second optical waveguides are formed is formed. This eliminates the need for angle alignment, and greatly reduces the alignment work compared to conventional direct coupling between end faces. Also, by not directly coupling the end faces to the optical coupling between the optical waveguides, it is possible to prevent the influence of the reflected return light. Further, the presence of the first or second tapered projections
The optical power is completely transferred from the optical waveguide to the third optical waveguide.
Missing waveguide propagation light can also be optically coupled.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of the present invention for a strip type optical waveguide. In the figure, 1
Is a core of the first optical waveguide, 2 is a cladding layer of the first optical waveguide, 3 is a core 1 and a cladding layer 2 of the first optical waveguide.
Is formed on the substrate, 4 is the core of the second optical waveguide, 5
Is a cladding layer of the second optical waveguide, 6 is a substrate on which the core 4 and the cladding layer 5 of the second optical waveguide are formed, 7 is a core of the third optical waveguide, and 8 is a cladding of the third optical waveguide. The layer 9 is a third substrate on which the core 7 and the cladding layer 8 of the third optical waveguide are formed.

The cores 1 and 4 and the cladding layers 2 and 5 are made of an optical waveguide material such as a polyimide organic material having the same refractive index, and are made of first and second substrates 3 and 2 made of alumina or Si. After spin-coating and curing each of the cores 6, the cores 1 and 4 are formed into a rectangular structure by reactive etching or the like. Each of the cores 1 and 4 and the cladding layers 2 and 5 has a thickness of about several microns to 50 microns, and a core width of about several microns to 50 microns.

The core 7 includes the cores 1 and 4 and the cladding layer 8.
Are made of an optical waveguide material such as a polyimide-based organic material having the same refractive index as the cladding layers 2 and 5, each having a thickness of several microns to 50 microns, and a core width of approximately several microns to 5 microns.
The film has a thickness of about 0 μm and a cladding width of several mm to cm square. This core 7 may be covered with a thin optical waveguide cladding layer of several microns or less as necessary. Thus,
The third optical waveguide according to the present embodiment has the same width and flexibility as the first and second optical waveguides.

The formation of the third optical waveguide according to this embodiment is as follows.
For example, an optical waveguide core layer and a clad layer are spin-coated and cured on a silicon wafer (not shown), a mask for forming the optical waveguide core is formed by a lift-off method or the like, and then the core 7 is formed by the same method as described above. Then, it is obtained by peeling off the interface between the optical waveguide clad and the silicon substrate. The cladding layer 8 further includes a third substrate 9 made of acrylic or the like.
The substrate 9 can be omitted if necessary.

In this embodiment, first, the core 1 and the core 7
The core 7 is completely brought into contact with a part of the surface of the core 1 in the longitudinal direction after the longitudinal direction (x, z-axis direction) of the core 1 is aligned by a positioning device (not shown). After the contact, it is fixed with an ultraviolet curable adhesive as needed. In this case, the refractive index of the adhesive is equal to that of the cladding layers 2 and 8. By bringing the core 7 and the core 4 into contact in a similar manner, the first and second optical waveguides can be coupled.

FIG. 2 is a sectional view showing a second embodiment of the present invention. In the figure, 1 is the core of the first optical waveguide, and 2 is the first optical waveguide.
The cladding layer 3 of the optical waveguide is a core 1 of the first optical waveguide.
A substrate on which the cladding layer 2 is formed; 4, a core of the second optical waveguide; 5, a cladding layer of the second optical waveguide;
Is a substrate on which the core 4 and the cladding layer 5 of the second optical waveguide are formed, 7 is the core of the third optical waveguide, 8 is the cladding layer of the third optical waveguide, and 9 is the third optical waveguide core 7 And the third substrate 10a on which the cladding layer 8 is formed,
Reference numeral 10b denotes a protrusion formed on the third optical waveguide core. The cores 1 and 4 and the cladding layers 2 and 5 are each made of an optical waveguide material such as a polyimide organic material having the same refractive index.
After spin coating and curing on each of the cores 6, the cores 1 and 4 are formed into a rectangular structure by reactive etching or the like. Each of the cores 1 and 4 and the cladding layers 2 and 5 has a thickness of about several microns to 50 microns, and a core width of about several microns to 50 microns.

The core 7 includes cores 1 and 4 and a cladding layer 8.
Are made of an optical waveguide material such as a polyimide-based organic material having the same refractive index as the cladding layers 2 and 5, each having a thickness of about several microns to 50 microns, a core width of about several microns to 50 microns, and a cladding width of several mm to cm. This is a corner film.

The projections 10a and 10b are formed on the core 7 and have the same refractive index, width and thickness as the core 7, and their longitudinal dimensions are from the core 1 to the core 7 and from the core 7 to the core 7. It is configured to have a length (-complete coupling length) at which the optical power transfer from the optical fiber to the core 4 becomes maximum. The protrusions 10a,
10b may be covered with a thin optical waveguide cladding of several microns or less as required.

Thus, the third waveguide according to the present embodiment has the same width as the first and second waveguides, is flexible, and has the projections 10a and 10b.

The formation of the third optical waveguide according to the present embodiment is as follows.
For example, an optical waveguide core layer and a clad layer are spin-coated and cured on a silicon wafer (not shown), and a mask for forming the optical waveguide core is formed by a lift-off method or the like. The mask is formed by the same method, and subsequently, the projections 10a and 10b and the core 7 are simultaneously formed by reactive ion etching or the like, and then the mask is obtained by peeling the interface between the optical waveguide clad and the silicon substrate. The clad layer 8 further adheres a third substrate 9 made of acrylic or the like, but this substrate 9 can be omitted if necessary.

In this embodiment, first, the core 1 and the core 7
After the alignment in the longitudinal direction (x, z-axis directions) of the core 1 is performed by a positioning device (not shown), the protrusions 10a and 10b are completely brought into contact with a part of the surface of the core 1 in the longitudinal direction. After the contact, it is fixed with an ultraviolet curable adhesive as needed. In this case, the refractive index of the adhesive is equal to that of the cladding layers 2 and 8. By bringing the protrusions 10a and 10b into contact with the core 4 in a similar manner, the first and second optical waveguides can be coupled.

According to the first and second embodiments as described above, the third optical waveguide in the form of a film having flexibility is formed by the first optical waveguide.
And connecting the first and second optical waveguides by contacting a part of the surface in the longitudinal direction of the second optical waveguide, so that the flexibility of the film can be utilized and the first and second optical waveguides can be used. Positioning in the height direction and positioning of the angle formed by the planes on which the first and second optical waveguides are formed become unnecessary, and the positioning work can be greatly reduced as compared with the conventional direct coupling between end faces. . Also, by not directly coupling the end faces to the optical coupling between the optical waveguides, it is possible to prevent the influence of the reflected return light.

FIG. 3 is a sectional view showing a third embodiment of the present invention. In the figure, 1 is the core of the first optical waveguide, 2 is the cladding layer of the first optical waveguide, 3 is the substrate on which the core 1 and the cladding layer 2 of the first optical waveguide are formed, and 4 is the second
5 is a core of the optical waveguide, 5 is a cladding layer of the second optical waveguide,
6 is a substrate on which the core 4 and the cladding layer 5 of the second optical waveguide are formed, 17 is the core of the third optical waveguide, 18 is the cladding layer of the third optical waveguide, and 19 is the substrate of the third optical waveguide. This is a third substrate on which a core 17 and a cladding layer 18 are formed.

The cores 1 and 4 and the cladding layers 2 and 5 are made of an optical waveguide material such as a polyimide organic material having the same refractive index, and are made of first and second substrates 3 made of alumina or Si. After spin coating and curing on each of the cores 6, the cores 1 and 4 are formed into a rectangular structure by reactive etching or the like. Cores 1 and 4 and cladding layers 2
5 have a thickness of several microns to 50 microns, respectively, and a core width of several microns to 50 microns.

The core 17 is made of an optical waveguide material such as a polyimide organic material having the same refractive index as the cores 1 and 4 and the third cladding layer 18 is the same as the cladding layers 2 and 5, and each has a thickness of several microns to 50 microns. Degree, core width is several microns ~
It is a film with a thickness of about 50 microns and a cladding width of several mm to cm square. This core 17 may be covered with a thin optical waveguide cladding layer of several microns or less as necessary. Thus, the third waveguide according to the present embodiment has the same width as the first and second waveguides and has flexibility.

The third optical waveguide film according to the present embodiment is formed, for example, by spin-coating and curing an optical waveguide core layer and a clad layer on a silicon wafer (not shown), and lifting off a mask for forming the optical waveguide core. After forming by a method or the like, the core 17 is formed by the same method as described above, and further, a tapered shape is produced while sequentially changing the beam scanning region with the focused ion beam or the like in the depth direction of the optical waveguide, Finally, it is obtained by peeling off the interface between the optical waveguide clad and the silicon substrate. The clad layer 8 further adheres a substrate 9 made of acrylic or the like, but this substrate 9 can be omitted if necessary.

In this embodiment, first, the core 1 and the core 1
After the longitudinal direction (x, z-axis directions) of 7 is aligned by an alignment device (not shown), the core 17 is completely brought into contact with a part of the surface of the first core 1 in the longitudinal direction. After the contact, it is fixed with an ultraviolet curable adhesive as needed. In this case, the adhesive has the same refractive index as the cladding layers 2 and 18. By bringing the core 17 and the core 4 into contact in a similar manner, the first and second optical waveguides can be coupled.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention. In the figure, 1 is the core of the first optical waveguide, and 2 is the first optical waveguide.
The cladding layer 3 of the optical waveguide is a core 1 of the first optical waveguide.
A substrate on which the cladding layer 2 is formed; 4, a core of the second optical waveguide; 5, a cladding layer of the second optical waveguide;
Is a substrate on which the core 4 and the cladding layer 5 of the second optical waveguide are formed, 17 is a core of the third optical waveguide, 18 is a cladding layer of the third optical waveguide, and 9 is a core of the third optical waveguide. The third substrate 10 on which the 17 and the cladding layer 18 are formed indicates protrusions formed on the third optical waveguide core.

The cores 1 and 4 and the cladding layers 2 and 5 are made of an optical waveguide material such as a polyimide organic material having the same refractive index, and are respectively spin-coated on substrates 3 and 6 made of alumina or Si. After curing, the cores 1 and 4 are formed into a rectangular structure by reactive etching or the like. The thickness of each of the cores 1 and 4 and the cladding layers 2 and 5 is about several microns to 50 microns, and the core width is several microns to
It is about 50 microns.

The core 17 is made of an optical waveguide material such as a polyimide-based organic material having the same refractive index as the cores 1 and 4 and the clad layer 18 and the clad layers 2 and 5. The film has a width of several microns to 50 microns and a cladding width of several mm to cm square.

The protrusions 10a and 10b are formed on the core 17 and have the same refractive index, width and thickness as those of the core 7, and their lengthwise dimensions are from the core 1 to the core 17 and from the core 17 to the core 17. It is configured to have a length (-complete coupling length) at which the optical power transfer from the optical fiber to the core 4 becomes maximum. The protrusion 10
a and 10b may be covered with a thin optical waveguide cladding of several microns or less as required.

Thus, the third optical waveguide according to the present embodiment has the same width as the first and second optical waveguides, has flexibility, and has the projections 10a and 10b.

The formation of the third optical waveguide according to the present embodiment is as follows.
For example, an optical waveguide core layer and a clad layer are spin-coated and cured on a silicon wafer (not shown), and a mask for forming the optical waveguide core is formed by a lift-off method or the like. A mask is formed by the same method, and subsequently, the protrusions 10a and 10b and the core 17 are simultaneously formed by reactive ion etching or the like, and thereafter, the interface between the optical waveguide cladding and the silicon substrate is peeled off. The cladding layer 18 further adheres a substrate 9 made of acrylic or the like, but this substrate 9 can be omitted if necessary.

In this embodiment, first, the core 1 and the core 1
After the longitudinal direction (x, z-axis directions) of the core 7 is aligned by a positioning device (not shown), the protrusion 10 a formed on the core 17 is completely brought into contact with a part of the surface of the core 1 in the longitudinal direction. . After the contact, it is fixed with an ultraviolet curable adhesive as needed. In this case, the adhesive has the same refractive index as the cladding layers 2 and 18. By bringing the protrusion 10b formed on the core 17 into contact with the second optical waveguide core 4 in a similar manner, the first and second optical waveguides can be coupled.

According to the third and fourth embodiments as described above, in addition to the same operations as in the above-described first and second embodiments,
Since light due to total reflection at the tapered portion can also be coupled, the spectral coupling efficiency is improved.

FIG. 5 is a sectional view showing a fifth embodiment of the present invention. In the figure, 1 is the core of the first optical waveguide, and 2 is the first optical waveguide.
The cladding layer 3 of the optical waveguide is a core 1 of the first optical waveguide.
A substrate on which the cladding layer 2 is formed; 4, a core of the second optical waveguide; 5, a cladding layer of the second optical waveguide;
Is a substrate on which the core 4 and the cladding layer 5 of the second optical waveguide are formed, 7 is the core of the third optical waveguide, 8 is the cladding layer of the third optical waveguide, and 9 is the core of the third optical waveguide. A third substrate on which 7 and a cladding layer 8 are formed, 20
Reference numerals a and 20b denote tapered projections formed on the third optical waveguide core.

The cores 1 and 4 and the cladding layers 2 and 5 are made of an optical waveguide material such as a polyimide organic material having the same refractive index, and are respectively spin-coated on substrates 4 and 6 made of alumina, Si or the like. After curing, the cores 1 and 4 are formed into a rectangular structure by reactive etching or the like. The thickness of each of the cores 1 and 4 and the cladding layers 2 and 5 is about several microns, and the core width is about several microns to 50 microns.

The core 7 comprises the cores 1 and 4 and the cladding layer 8
Are made of an optical waveguide material such as a polyimide-based organic material having the same refractive index as the cladding layers 2 and 5, each having a thickness of about several microns to 50 microns, a core width of about several microns to 50 microns, and a cladding width of several mm to cm. This is a corner film. This core 7 may be covered with a thin optical waveguide cladding of several microns or less as necessary.

The projections 20a and 20b have the same refractive index, width and thickness as the core 7, and are formed on the core 7 and in the vicinity of the overlapping portion between the first and second optical waveguides and the third optical waveguide. The first and second optical waveguides are formed so as to face each other, and have a taper on the opposite side that does not face the first and second optical waveguides.

Thus, the third optical waveguide according to the present embodiment has the same width as the first and second optical waveguides, has flexibility, and has the projections 20a and 20b.

The formation of the third optical waveguide according to this embodiment is as follows.
For example, an optical waveguide core layer and a cladding layer are spin-coated and cured on a silicon wafer (not shown), and a mask for forming the optical waveguide core is formed by a lift-off method or the like. A projection forming mask is formed by the same method, and then the projections 20a and 20a are formed into a tapered shape by reactive ion etching.
After forming the core 20b and the core 7 at the same time, a taper is formed on the projections 20a and 20b while sequentially changing the scanning area of the beam or the like with the focused ion beam in the depth direction of the projections 20a and 20b. By peeling the interface between the substrate and the silicon substrate. The clad layer further adheres a substrate 9 made of acrylic or the like, but this substrate 9 can be omitted if necessary.

In this embodiment, first, the core 1 and the core 7
The core 7 is completely brought into contact with a part of the surface of the core 1 in the longitudinal direction after the longitudinal direction (x, z-axis direction) of the core 1 is aligned by a positioning device (not shown). After the contact, it is fixed with an ultraviolet curable adhesive as needed. In this case, the refractive index of the adhesive is equal to that of the cladding layers 2 and 8. By bringing the core 7 and the core 4 into contact in a similar manner, the first and second optical waveguides can be coupled.

FIG. 6 is a sectional view showing a sixth embodiment of the present invention. In the figure, 1 is the core of the first optical waveguide, and 2 is the first optical waveguide.
The cladding layer 3 of the optical waveguide is a core 1 of the first optical waveguide.
A substrate on which the cladding layer 2 is formed; 4, a core of the second optical waveguide; 5, a cladding layer of the second optical waveguide;
Is a substrate on which the core 4 and the cladding layer 5 of the second optical waveguide are formed, 7 is a third optical waveguide core, 8 is a cladding layer of the third optical waveguide, and 9 is a core 7 of the third optical waveguide. And the third substrate 10a on which the cladding layer 8 is formed,
10b is a projection for superimposing the first and second optical waveguides formed on the core 7 of the third optical waveguide, and 20a, 2
0b denotes a tapered projection formed on the core 7 of the third optical waveguide.

The cores 1 and 4 and the cladding layers 2 and 5 are made of an optical waveguide material such as a polyimide organic material having the same refractive index, and are respectively spin-coated on substrates 3 and 6 made of alumina, Si or the like. After curing, the cores 1 and 4 are formed into a rectangular structure by reactive etching or the like. The thickness of each of the cores 1 and 4 and the cladding layers 2 and 5 is about several microns to 50 microns, and the core width is several microns to
It is about 50 microns.

The core 7 includes the cores 1 and 4 and the cladding layer 8.
Are made of an optical waveguide material such as a polyimide-based organic material having the same refractive index as the cladding layers 2 and 5, each having a thickness of about several microns to 50 microns, a core width of about several microns to 50 microns, and a cladding width of several mm to cm. This is a corner film.

The protrusions 10a, 10b, 20a and 20b have the same refractive index and width as the core 7, the thickness of the protrusions 10a and 10b is equal to that of the core 7, and the thickness of the protrusions 20a and 20b is
Is formed twice or more. Also, the projections 20a, 20b
Is formed at a position facing the first and second optical waveguides, and has a taper on the opposite side not facing the first and second optical waveguides. The longitudinal dimension of the projections 10a and 10b is the length (= complete coupling length) at which the optical power transfer from the core 1 to the core 7 and from the core 7 to the core 4 becomes maximum. The projections 10a and 10b formed on the third optical waveguide core may be covered with a thin optical waveguide clad of several microns or less as necessary.

Thus, the third optical waveguide according to the present embodiment has the same width as the first and second waveguides, is flexible, and has the projections 10a, 10b, 20a, and 20b. .

The formation of the third optical waveguide film according to this embodiment is performed, for example, by spin-coating and curing the optical waveguide core layer and the cladding layer on a silicon wafer (not shown), and lifting off the optical waveguide core forming mask. After being formed by a method or the like, a projection optical waveguide layer and a projection forming mask are formed by the same method, and subsequently, the projections 10a, 10b, 20a, and 20b are formed by reactive ion etching or the like.
And the core 7 are formed at the same time, and for the projections 20a and 20b, a beam
It is obtained by forming a taper while sequentially changing it in the depth direction of a and 20b, and then peeling off the interface between the optical waveguide clad and the silicon substrate. The clad layer 8 further adheres a substrate 9 made of acrylic or the like, but this substrate 9 can be omitted if necessary.

In this embodiment, first, the cores 1 and 7
After the alignment in the longitudinal direction (x, z-axis directions) of the core 1 is performed by a positioning device (not shown), the protrusions 10a and 10b formed on the core 7 are completely brought into contact with a part of the surface in the longitudinal direction of the core 1. Let it. After the contact, it is fixed with an ultraviolet curable adhesive as needed. In this case, the refractive index of the adhesive is equal to that of the cladding layers 2 and 8. By bringing the protrusions 10a, 10b formed on the third optical waveguide core into contact with the second optical waveguide core 4 in a similar manner, the first and second optical waveguides can be coupled.

According to the third and fourth embodiments as described above, in addition to the same operations as in the above-described first and second embodiments,
Tapered projections 20a, 20 are located on the third optical waveguide surface at positions facing the first optical waveguide and the second optical waveguide.
By providing b, waveguide-propagating light whose optical power cannot be completely transferred from the first optical waveguide or the second optical waveguide to the third optical waveguide can be optically coupled.

In the first to sixth embodiments as described above, the core 7 does not need to be formed only by a straight line.
A circuit such as a bend or a branch may be formed. Also,
It goes without saying that the first optical waveguide and the second optical waveguide may be formed on the same substrate. Further, it goes without saying that the optical waveguide material may be an acrylic material (for example, polymethacrylate). In addition, it goes without saying that the optical coupling structure of the present invention can be applied to a ridge-type embedded waveguide in addition to the strip-type optical waveguide.

[0049]

According to the present invention, the first optical waveguide and the second optical waveguide are connected by the third optical waveguide made of a flexible film, as described above in detail with the embodiments. With this configuration, it is not necessary to align the height of the second optical waveguide in the height direction and the angle between the planes on which the first and second optical waveguides are formed. The alignment work can be greatly reduced as compared with the connection, which is effective in reducing the mounting cost. In addition, since the end faces are not directly coupled to each other, the influence of the reflected return light at the coupling interface on the light propagating in the optical waveguide can be suppressed. Further, the presence of the first or second tapered projections
Optical power has not completely transferred from the optical waveguide to the third optical waveguide.
The light propagated through the waveguide can be optically coupled. Also,
The first or second optical waveguide due to the presence of the tapered protrusion
That the optical power could not transfer to the third optical waveguide
Road-propagating light can also be optically coupled.
The coupling efficiency is also improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a fifth embodiment of the present invention.

FIG. 6 is a sectional view showing a sixth embodiment of the present invention.

FIG. 7 is a sectional view showing a conventional technique.

[Explanation of symbols]

 1,4,7 core 2,5,8 cladding layer 3,6,9 substrate

──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-A-51-32343 (JP, A) JP-A-57-190516 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/12-6/26

Claims (1)

(57) [Claims] 1. A flexible, film-like structure between a first optical waveguide formed on a first substrate and a second optical waveguide formed on a second substrate. An optical coupling structure optically coupled through a third optical waveguide, wherein both ends of the third optical waveguide are both of the first and second optical waveguides.
The first and second optical waveguides are in contact with the end faces, respectively.
The third light guide near the overlapping portion with the optical waveguide
The first and second optical waveguides are made of the same material as the third optical waveguide.
A third optical waveguide opposing the end face of the second optical waveguide, respectively.
A projection having the same width as the road is provided, and the projections are the first and second projections.
2 in the thickness direction on the side opposite to the side facing the optical waveguide.
Has a path, further at both ends of the third optical waveguide, moreover the first and second
The portion corresponding to the overlapping portion with the optical waveguide of
It has a projection of the same material as the optical waveguide material, and this projection is
3. An optical coupling structure between the optical waveguides, wherein the projections have the same width as the optical waveguide of No. 3 .