JPS61148406A - Optical coupling device - Google Patents

Abstract

PURPOSE:To constitute a compact optical circuit device by arranging the 1st and the 2nd substrates which have optical waveguide provided to the 2nd substrate with the optical waveguide of the 1st substrate while leaving a gap. CONSTITUTION:An optical waveguide 11 having a photodetecting element 16 and an optical waveguide 15 having a light emitting element 12 are formed on the base substrate 10. Then, an optical waveguide 21 which has a light emitting element 22 and an optical processing part 23 and an optical waveguide 25 which has a photodetecting element 26 and an optical processing part 27 are formed on a circuit substrate 20. Then, the base substrate 10 and circuit substrate 20 are arranged at right angles. The optical waveguide 21 is extended to an end surface 20a where the circuit substrate 20 contacts the base substrate 10 with a fine gap left to form and optical waveguide part 21a for coupling and also form a slanting surface 24. Light propagated in the optical waveguide 21 is reflected totally by the slanting surface 24 and propagated from the optical waveguide part 21a to an optical waveguide 11. Consequently, the light transmission and reception between the two substrates is facilitated and the integrated optical circuit device is made compact.

Description

BACKGROUND OF THE INVENTION The present invention relates to an optical coupling device for transmitting and receiving light between two substrates.

In recent years, research has been actively conducted on techniques to integrate and create many optical processing functions on one substrate. , an optical waveguide is formed in the substrate to guide light to a desired location on the substrate.

When many optical functional elements are integrated on one substrate, the light must be propagated vertically and horizontally, so it is inevitable that the optical waveguides used to propagate the light will sometimes cross each other. . At intersections of optical waveguides, light propagating through one optical waveguide leaks to the other intersecting optical waveguide, resulting in a problem of increased cross talk rings and an increase in the S/N ratio. From this point of view, the number of optical functional elements that can be integrated on a -substrate is naturally limited.

Therefore, one possible way to realize many optical functions in a compact manner is to arrange multiple substrates three-dimensionally. When a plurality of substrates are arranged three-dimensionally, it is necessary to transmit and receive light between the substrates.

SUMMARY OF THE INVENTION An object of the present invention is to enable transmission and reception of light between two substrates with a relatively simple structure, and to provide a means for realizing a compact integrated optical circuit.

An optical coupling device according to the present invention includes a first substrate on which an optical waveguide is formed, and a second substrate arranged perpendicularly to the surface of the first substrate to be coupled, and on whose surface an optical waveguide is formed. A coupling optical waveguide is formed on the end face of the second substrate, and the coupling optical waveguide is optically coupled to the optical waveguide on the surface of the second substrate via the total reflection surface. It is characterized by facing the optical waveguide on the surface of the substrate to be coupled with a small gap therebetween.

The optical coupling device according to the present invention has bidirectionality, so
Not only can light be guided from the second substrate to the second substrate, but also light can be transmitted from the second substrate to the first substrate. According to this invention, light can be freely exchanged between two substrates. Further, the configuration is simple and adjustment is easy. Furthermore, according to this invention, it is possible to perform optical coupling by arranging two substrates perpendicularly to each other, so it is possible to increase the degree of integration by arranging two substrates three-dimensionally without increasing the area of one substrate. You can also do it. Since it is possible to suppress the planar expansion of the substrate, it is useful for realizing an overall compact integrated optical circuit.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments in which the present invention is applied to a three-dimensional optical circuit device will be described in detail.

(1) Three-dimensional optical circuit device FIG. 1 shows an outline of the three-dimensional optical circuit device.

Mother board (10) and multiple circuit boards (2G) (3
0) (40) is fixedly supported on the support (1).

Each circuit board (20) to (40) is in contact with the mother board (10) at right angles. Mother board (10) and circuit board (
20) to (40) are formed by integrating optical waveguides and optical functional elements constituting a desired optical circuit. An example of the optical waveguide formed on the motherboard (10) is (11)
(15).

A light receiving element (
16) and a light emitting element (12) for transmitting light to the optical waveguide (15) are fixed to the end surface of the motherboard (10). Examples of optical waveguides formed on the circuit board (20) are shown in (21) and (25), and optical functional elements or optical processing units provided in the middle of these optical waveguides (21) and (25) An example is shown in (23) (2γ). The optical waveguide (21) and the optical processing section (23) are formed on the upper surface of the circuit board (20), and the optical waveguide (25) and the optical processing section (21) are formed on the lower surface of the substrate (20). Light from the light emitting element (22) is guided to the optical waveguide (21), and light propagated through the optical waveguide (25) is guided to the light receiving element (26).
) is received. These elements (22) (26) are fixed to the end face of the circuit board (20). As is well known, an optical waveguide is formed by diffusing a predetermined substance into a substrate. Similarly, the circuit board (30) also has optical waveguides (31) (35) and an optical processing section (33).
(37), light emitting element (32), light receiving element (36)
etc. are provided. Although not shown in the figure, other optical waveguides, optical functional elements or optical processing units, emitters,
The light receiving elements etc. are connected to the mother board (io), the circuit boards (20) to (4)
0).

(2) Circuit boards and optical coupling devices The optical waveguides on the circuit boards (20) to (40) and the optical coupling devices between these circuit boards (20) to (40) and the mother board (10) are all Since they have the same configuration, the circuit board (20) and its optical waveguide (21) will be explained as an example.

2 and 4, the optical waveguide (21) formed on the circuit board (20) is connected to the motherboard (10) of the board (20).
) extends to the end surface (20a) in contact with. The optical waveguide on the end face is a coupling optical waveguide, which is called (21a)
Indicated by Then, the front surface of the circuit board (20) and the end surface (2
The edge with 0a) is notched at an angle of 45° to form a slope (24). This slope (24) becomes a total reflection surface. Light propagating through the optical waveguide (24) is totally reflected on the slope (24) and heads toward the optical waveguide (21a).If there is light propagating through the optical waveguide (21a), this light is totally reflected on the slope (24). Needless to say, the light is then directed to the optical waveguide (21).

The refractive index of the optical waveguide (21) is 01, and the refractive index of air is n2.
= 1, and if the angle between the incident light on the slope (24) and the normal to the slope (24) is θ, then the incident light will be on the slope (24).
The condition for total reflection is given by sinθ〉n2/nlte. When the substrate (20) is made of LiNbO3, its refractive index is about 2.2, and when it is made of glass, it is about 1.5. If these refractive indices are adopted as 01, the total reflection conditions described above will be θ>27' and θ>42°, respectively. Since the angle between the surface of the substrate (20) and the end surface is usually a right angle, the slope (24) has an inclination of 456 degrees. Therefore, since θ shown in FIG. 4 is 45°, the slope (24) satisfies the condition for total reflection.

In FIG. 2, the optical waveguide (
11) and the optical waveguide (21a) on the end surface (20a) of the circuit board (20) face each other. Also mother board (10)
Although the surface of the circuit board (20) and the end surface (20a> of the circuit board (20) are in close contact with each other, there is actually a small gap (20a) between the two surfaces).
wavelength order). Therefore, the mother substrate (io), its optical waveguide (ti), the gap between the above-mentioned surfaces, and the optical waveguide (2)
1a) and the circuit board (20) can be considered to have a five-layer two-dimensional optical waveguide structure. In such a five-layer two-dimensional optical waveguide structure, light propagating through the optical waveguide (21a) gradually transfers to the optical waveguide (11) as the light propagates, and at a certain length (perfect coupling length), the light propagates through the optical waveguide (11). >The entire power is transferred from the optical waveguide (21a) to the optical waveguide (11
), the power of the light transferred to the imaging optical waveguide (21a >
(11) depends on the length of the overlapping portion (bond length). In the case of perfect coupling length, the total optical power is
1a) to the optical waveguide (11). Therefore, the light propagating through the optical waveguide (21) is totally reflected on the slope (24) and proceeds to the optical waveguide (21a), and then moves to the optical waveguide (11) at a rate roughly corresponding to the coupling length. (11) will be propagated.

Needless to say, if there is light propagating through the optical waveguide (11), this light moves to the optical waveguide (21a) and then further to the optical waveguide (21).

FIG. 3 shows an optical waveguide (21) (28) formed on both the upper and lower (front and back) surfaces of a circuit board (20), and an optical waveguide (21) (28) formed on the end face of the circuit board (20).
21a) through a total reflection surface. The light in the optical waveguide (21) moves from the optical waveguide (21a) to the optical waveguide (11) of the mother board (10). Further, the light in the optical waveguide (11) moves to the optical waveguide (21a) and proceeds to the optical waveguide (28).

FIG. 5 shows a method for making optical waveguides such as those shown in FIGS. 2 and 3. For example, a KNO3 solution is contained in the tank (60). Substrate material, e.g. 1-
The iNboa substrate (10) and the electrode 1 (61) are immersed in this solution.

A slope (total reflection surface) is formed in advance on the edge of the substrate (70) and optically polished. The substrate (70) is connected to the negative terminal of the DC power supply (62), and the electrode (61) is connected to the switch (63).
are respectively connected to the positive electrode through. Switch (6
3) is turned on, the + ions in the KNOa solution are attracted to the substrate (70) and diffuse into the substrate (70).

As a result, an optical waveguide in which + is diffused is formed in the substrate (70). This is a method called ion exchange method. If the surface of the substrate (γ0) other than the part where the optical waveguide is to be formed is masked, an optical waveguide with a desired pattern can be created; if no mask is applied, the surface of the substrate (70)
Optical waveguide layers (paths) are formed on the front and back, edges, sides, and slopes of the substrate.

(3) Effects of the three-dimensional optical circuit device Returning to FIG. 1, the light output from the light emitting element (12) propagates through the optical waveguide (15) on the motherboard (10),
The light is transferred at an appropriate rate to the optical waveguides (25) (35) formed on the bottom surfaces of the circuit boards (20) (30) by the optical coupling device described above, and is propagated through these optical waveguides (25) (35), respectively. Then, the light processing section (27) (3
γ), and then the light is received by each light receiving element (2G>(3G>). In this way,
Light is transmitted from the motherboard (10) to multiple circuit boards (20> (
30) etc.

The light output from the light emitting element (22) is transmitted to the circuit board (20)
After being guided through the optical waveguide (21) formed on the top surface and subjected to appropriate processing in the optical processing section (23), it further advances through the optical waveguide (21) and is connected to the mother substrate via the above-mentioned optical coupling device. (
10) Move to the upper optical waveguide (11). The light then propagates through the optical waveguide (11) and is received by the light receiving element (16).

Light output from the light emitting element (32) on the circuit board (30) and propagating through the optical waveguide (31) is also extracted from the optical waveguide (11) on the motherboard (10) in the same way. In this way, light propagating on the plurality of circuit boards (20), (30), etc. can be extracted from the mother board (10).

The above-mentioned introduction and extraction of light may be performed simultaneously, or may be performed at different temporal timings (for example, in a time-sharing manner). Optical waveguide and circuit board (20) on motherboard (10)
) (30) etc. By setting the coupling efficiency with the above optical waveguide to a desired value, it becomes possible to introduce and extract an arbitrary amount of light.

For example, light can also be transmitted and received between optical waveguides on a plurality of circuit boards via the mother board (10), such as from the circuit board (20) to the circuit board (30).

In the above embodiment, a three-dimensional optical waveguide is formed on each substrate, but a high refractive index layer is formed on the entire surface of each substrate (back, end, side), and this is used as an optical waveguide (layer). You can also use it as Of course, a waveguide lens can also be formed on the optical waveguide (layer) for optical coupling with the light emitting and light receiving elements.

It is also possible to optically couple two circuit boards in a plane by abutting their end faces on which coupling waveguides are formed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a three-dimensional optical circuit device, FIGS. 2 and 3 are sectional views showing an example of an optical coupling device, and FIG.
The figure is a sectional view showing an enlarged corner of the circuit board, and FIG. 5 is a configuration diagram for explaining an example of a method for manufacturing the circuit board. (10)... Mother board, (11) (15)... Optical waveguide of mother board, (20) (30) (40
)...Circuit board, (21) (25) (31)
(35)... Optical waveguide of circuit board, (21a)...
-Coupling optical waveguide, (24)...total reflection surface. 4 people other than the above @ 1 Figure 4 Figure 5 Procedure amendment (related) January 3, 1986

Claims (1)

[Claims] A first substrate on which an optical waveguide is formed, and a second substrate arranged perpendicularly to a surface of the first substrate to be bonded and on which an optical waveguide is formed, the second substrate having an optical waveguide formed thereon. A coupling optical waveguide is formed on the end face, and the coupling optical waveguide is optically coupled to the optical waveguide on the surface of the second substrate via the total reflection surface, and the surface of the first substrate to be coupled. An optical coupling device that faces the optical waveguide with a small gap.