JP3365591B2 - Optical connection integrated circuit - 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 substrate for optical connection between a plurality of integrated circuit devices and within each device, and an optical connection integrated circuit optically connected to each other.

[0002]

2. Description of the Related Art Due to the progress of semiconductor integrated circuit technology, a large number of integrated circuit chips with various functions and scales are used in electronic systems in the fields of communication and computers, as well as various information devices such as video and audio processing. It is used. As the sophistication of society progresses, the demand for multimedia environment is especially increasing, and higher speed and larger amount of signal / information processing are required. In order to improve the processing capability of the entire electronic system that performs such information processing, it is essential to improve the performance of the integrated circuit chip itself that constitutes it.

With regard to chips that meet this demand, while pursuing high speed by miniaturizing elements, the processing capacity has been expanded by increasing the number of mounted elements. In addition to the high performance of chips, it is necessary to exchange a large amount of data between chips at high speed, and efforts have been made to realize high-speed and large-capacity interconnection between chips. This is achieved by shortening the electrical wiring between chips on the mounting board as much as possible, simultaneously increasing the number of chip input / output terminals, and transmitting a large amount of data collectively with as many wirings as possible. To be done.

The multi-chip module (MCM) has been attracting attention as one that satisfies such requirements. However, even in this MCM, in order to increase the wiring density,
When the wirings are made finer and narrower, the wiring resistance increases and the stray capacitance between the wirings also increases.
As a result, the load impedance becomes large, and the charge and discharge thereof cause an increase in signal delay and an increase in power consumption of the input / output circuit.

The wiring load is reduced if the wiring length is shortened, but the chip size is increased as the system speed increases,
While the total wiring length increases as the number of chips increases, the average length does not necessarily decrease. Further, in high-density wiring, signal crosstalk is apt to occur between wirings, which becomes more noticeable as the signal becomes faster and the spacing between the wirings becomes shorter. These are problems peculiar to electric wiring, and a fundamental solution is difficult.

In order to avoid the above problems and realize a higher-speed and large-capacity interconnection, an optical interconnection between chips is expected. Although several methods have been proposed so far, FIG. 9 is a perspective view showing an example thereof, in which an arbitrary element is connected using an optical element such as a hologram (Reference 1: LABergman, WHWu, ARJohnston,
and R. Nixon, "Holographic optical interconnects for
VLSI, "Optical Engineering, Vol.25, No.10,1109,198
6).

In this method, first, the integrated circuit element 11 is
2. The light emitting / receiving elements such as the driving circuit 114, the laser diode 115, and the photodiode 113 are placed on the plane of the same substrate. Then, a reflecting surface 111 is provided in parallel with these surfaces at a constant distance, and a hologram element (not shown) is arranged thereon. Here, the hologram element is
The incident light is reflected at an arbitrary angle different from the incident angle. And the element surface (laser diode 115)
The light emitted from is deflected by the hologram element,
A signal is transmitted by reflecting the light toward a light receiving element (photodiode 113) at an arbitrary point on the element surface.

As a modification of this, an MCM structure by optical transmission configured as shown in FIG. 10 has been proposed (Reference 2: MR Feldman, JE Morris, I. Turlik, P. Magill, GA).
dema, and YARaja, "Holographic Optical Interconnec
ts for VLSI Multichip Modules, "IEEE Trans.Componen
ts, Packaging, and ManufacturingTech.-B, Vol.17, No.2,
223, 1994). FIG. 10 is a cross-sectional view showing the configuration of the MCM by optical transmission, in which 121 is a substrate, 122 is an integrated circuit element provided with a light receiving portion arranged on the substrate 121, 123 is a light emitting element, and 124 is a light emitting element 123. A hologram element that receives light emitted from the hologram element and emits the light in a predetermined direction, 125 is a transparent flat substrate on which the hologram element 124 is arranged and faces the substrate 121, and 126 is disposed on the flat substrate 125. It is a flat reflector.

In this case, for example, the optical signal emitted from the leftmost light emitting element 123 in the figure is bent in a predetermined direction by passing through the hologram element 124 thereabove and reflected by the flat reflecting mirror 126. This reflected optical signal is reflected by the reflection hologram element 126a on the flat substrate 125,
The light is reflected by the flat reflecting mirror 126 again, is deflected here through the hologram element 124 at the right end in the figure, and enters the light receiving portion of the integrated circuit element 122 therebelow.

[0010]

However, in the above-mentioned method, first of all, there is a problem that the mounting dimension becomes large. That is, if the connection distance is to be increased, the distance between the surfaces must be increased, and if a large-scale system is to be configured, not only the area but also the thickness is increased in the mounting dimension.

Here, according to the method of FIG. 10, the problem in this respect can be somewhat avoided as compared with the method of FIG. According to the method of FIG. 10, the volume can be reduced by spatially folding back the connection height, that is, by repeating the reflection between the hologram surface and the reflecting surface. However, even in the method of FIG. 10, the realistic distance between the hologram surface and the reflection surface is still as large as 2 cm or more.

The second problem is that the loss of light quantity is large. In the method of FIG. 10, if the connection distance is increased without increasing the thickness, the number of reflections will increase. Generally, the diffraction efficiency of a computer generated hologram element is not high, and several tens of percent of the incident light amount becomes invalid. For this reason, the optical signal intensity is extremely reduced by being repeatedly reflected by the hologram element.

On the other hand, in order to reduce the number of reflections, it is possible to increase the diffraction angle of the hologram. However, for this purpose, it is necessary to reduce the minimum pitch of the hologram pattern, and the diffraction efficiency per hologram becomes even lower. As a result, the light transmission efficiency does not increase. Further, in order to improve the diffraction efficiency, it is necessary to set the step of the phase difference of the hologram pattern in several steps, and since the advanced fine processing technology is used, the processing cost increases.

Further, there is a decrease in efficiency due to the wavelength dispersibility of the hologram element. Even with the same hologram, if the incident light wavelength is different, the diffraction angle is different. Therefore, if the wavelength of the light emitting element fluctuates, the position where the deflected light reaches may deviate from the center of the light receiving element surface, resulting in a loss of the amount of light received. To reduce the effect of wavelength fluctuation,
Although it is necessary to combine a plurality of holograms, etc., the efficiency decreases and the manufacturing cost increases when they are combined.

The third problem is that it takes time and effort to optimize between arbitrary points, and all or part of the parts that realize the connection between arbitrary points are not standardized, resulting in high cost. is there. That is, when trying to connect a light emitting element at several places and a light receiving element at several places respectively, conventionally, the hologram element must be redesigned and optimized by considering the diffraction angle and the diffraction direction according to each connection path. I had to do it. In order to obtain an optimum hologram pattern that realizes a complicated circuit connection, calculation of a large amount of data is repeated many times, which requires a long calculation time. As described above, conventionally, complicated optimization is required, resulting in an increase in manufacturing cost.

The present invention has been made to solve the above problems, and an object thereof is to make it possible to reduce the mounting dimension without increasing the manufacturing cost.

[0017]

The optical connection integrated circuit of the present invention is composed of at least three planes orthogonal to each other and a plane parallel to any one of these planes, and in addition to the two planes facing each other in parallel. First and second transparent bodies that are orthogonal to each other and have a reflecting surface set at a predetermined angle with the other surface.
Of the reflective optical element, a flat substrate having a flat surface on which the first and second reflective optical elements are arranged, and a light emitting section for outputting an optical signal for optically connecting to a plane facing the flat substrate. And an integrated circuit board on which a second integrated circuit having a light receiving unit for inputting an optical signal for optical connection is arranged. Then, the first reflective optical element
The optical signal emitted from the light emitting portion of the first integrated circuit is used as an optical path parallel to the flat surface of the flat substrate, and the second reflective optical element is an optical path parallel to the flat surface of the flat substrate. The signal is changed so as to be incident on the light receiving portion of the second integrated circuit, whereby the first and second integrated circuits are optically connected. In addition, it is composed of at least three planes orthogonal to each other and a plane parallel to any of these planes, and in addition, it is orthogonal to the two planes facing each other in parallel and is set at a predetermined angle with the other planes. A third reflective optical element comprising a transparent body having a surface and changing the direction of the optical path by 90 ° in a plane parallel to the flat surface of the flat substrate; By arranging the third reflective optical element at a predetermined lattice point of a virtual lattice such that all the points where the second reflective optical element is disposed are on the lattice points, the first and second It is characterized in that the integrated circuits are optically connected. Further, it is composed of at least three planes orthogonal to each other and a plane parallel to any of these planes, and in addition, it is orthogonal to two planes facing each other in parallel and is set to a predetermined angle with other planes. A branched optical element made of a transparent material having a reflective surface is provided, and the first optical element is provided on the flat surface of the flat substrate.
By arranging the branching optical element at a predetermined lattice point of a virtual lattice such that all the points where the second optical element is disposed are on the lattice point, the first and second integrated circuits are separated from each other. It is characterized by optical connection.

[0018]

The optical signal propagates on the flat substrate in a state parallel to the flat surface by the optical element of a simple shape arranged on the flat substrate, thereby optically connecting the integrated circuits.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Example 1. FIG. 1 is a sectional view showing the structure of an optical connection integrated circuit according to an embodiment of the present invention. In the figure, 1
Is an integrated circuit substrate, 1a is an integrated circuit chip, 1b is a laser diode (LD) that sends out an optical signal, and 1c is a photodiode (PD) that receives an optical signal.

Reference numeral 2 is a flat substrate for optical connection, 3a is a minute optical element arranged so that the reflecting surface for total reflection makes an angle of 45 ° with the flat substrate 2, and 3b has a reflecting surface for semi-reflection. It is a minute optical element which is arranged so as to form an angle of 90 ° with the flat substrate 2 and which branches and changes the optical path on a plane parallel to the flat substrate 2. Reference numeral 4 is a solder bump that connects the integrated circuit substrate 1 and the flat substrate 2 at a predetermined interval.

The optical element 3a is arranged on the flat substrate 2 in accordance with the positions of the LDs 1b and PD1c on the integrated circuit substrate 1 connected to the integrated circuit chip 1a. Figure 1
(B), (c) is a perspective view which shows an example of an optical element. FIG. 1 (b) is a cubic optical element made of a transparent material in which a mirror or a beam splitter is arranged on a diagonal surface (hatched portion) passing through a diagonal line of a surface facing each other. A beam splitter with transmission and reflection of 1: 1 is a half mirror.

Further, FIG. 1C shows a rectangular parallelepiped optical element made of a transparent material, with a diagonal surface (hatched portion) passing through a diagonal line of opposing square surfaces serving as a reflecting surface. The transparent material may be quartz glass such as synthetic quartz or fused quartz, or glass material such as BK7.

The flat substrate 2 and the integrated circuit substrate 1 are
They are arranged to face each other by a method such as flip chip bonding. It should be noted that the light emitted from the LD 1b has a divergence angle, and in reality it is necessary to make it parallel light or focus it. However, for the sake of simplicity, these means will be omitted in the description.

The optical signal emitted from the LD 1b, which is a light emitting element, is incident on the flat substrate 2 substantially vertically, and its optical path is changed by the optical element 3a on the flat substrate 2 in a direction parallel or substantially parallel to the flat substrate 2. After that, the optical signal is kept in a substantially constant distance from the flat substrate 2, and the optical element 3b is used to repeat the course change and branch as necessary,
It propagates on a plane parallel or almost parallel to the flat substrate 2. Then, the optical signal has its course changed in a direction substantially perpendicular to the flat substrate 2 by the optical element 3a arranged directly below the light receiving element PD1c to be connected to the PD1c on the integrated circuit substrate 1. Incident.

When the optical signal propagates on a plane parallel or almost parallel to the substrate as described above, the integrated circuit substrate 1 and the flat substrate 2 for optical connection are formed even if the propagation distance of the optical signal becomes long. There is no need to increase the space. As a result, the mounting size of the entire system can be reduced. Further, an optical element including a reflective optical system such as a mirror or a semi-reflective branch optical system such as a half mirror may be used only for changing the path of an optical signal or for branching. That is, since reflection and refraction are not repeated in order to propagate a long distance, there is no demerit that the propagation efficiency is lowered even in a long distance propagation in the above-mentioned embodiment.

FIG. 2 shows the flat substrate 2 of FIG. 1 and the optical elements 3a-1 to 3a-3, 3b'-1, arranged on it.
It is a top view which shows the structure of 3b-2, 3b'-3. Figure 2
Are cubic optical elements 3a-1 to 3a-3 and optical elements 3b'- whose shapes and sizes are unified (normalized) on the lattice points of a lattice virtually arranged on the flat substrate 2. 1,
It shows a state in which only 3b-2 and 3b'-3 are arranged. The grid shown by the dotted line in the figure is the LD on the integrated circuit substrate.
And PD are designed to be placed on the grid points. Then, in FIG. 2, the LD is arranged on the optical element 3a-1, and the PD is arranged on the optical element 3a-2 and the optical element 3a-3.

The optical elements 3a-1 to 3a-3 shown in FIG. 2 are arranged so that the reflecting surface forms an angle of 45 ° with the surface of the flat substrate 2. That is, in the state shown in FIG. 1B, the bottom surface of the flat substrate 2 is in contact with the surface of the flat substrate 2. In addition, the optical elements 3b′-1, 3b′-3 having a total reflection surface and the optical element 3b-2 having a semi-reflective surface are such that the reflective surface or the semi-reflective surface forms an angle of 90 degrees with the surface of the flat substrate 2. It is located in. That is, in the state shown in FIG. 1B, the front surface of the flat substrate 2 is in contact with the surface of the flat substrate 2.

In FIG. 2, the solid arrow line shows the path of the optical signal. An optical signal emitted from an LD (not shown in FIG. 2) enters the optical element 3a-1 perpendicularly to the flat substrate 2 and is reflected by its reflection surface to change its course in parallel with the flat substrate 2. . The optical signal that is parallel to the surface of the flat substrate 2 is incident on the optical element 3b′-1, changes its direction by 90 °, and is incident on the optical element 3b-2. The optical signal incident on the optical element 3b-2 is the same as the optical signal traveling straight on its semi-reflective surface.
It is branched to an optical signal that changes the direction of 0 °.

Here, the optical signal traveling straight is the optical element 3
At b′-3, the direction is changed by 90 °, the light is incident on the optical element 3a-3, and the reflection surface changes the direction of travel by 90 ° with respect to the plane of the flat substrate 2 and the PD (not shown) is arranged on this.
Incident on. Further, the optical signal whose traveling direction is changed by 90 ° by the optical element 3b-2 is incident on the optical element 3a-2, whose traveling surface is changed by 90 ° with respect to the plane of the flat substrate 2, It is incident on a PD (not shown) to be arranged.
As described above, the optical connection from the LD to the PD on the integrated circuit substrate is realized.

As described above, the optical signal emitted from the LD of the integrated circuit board immediately changes its course and becomes parallel to the plane of the integrated circuit board. Since the optical signal propagates on a plane parallel to the plane of the integrated circuit substrate, it is not necessary to increase the distance between the integrated circuit substrate and the flat substrate even if the propagation destination is very far. That is, according to this embodiment, it is possible to connect a long distance by an optical signal between chips on the same substrate without increasing the thickness of the entire system.

Further, the optical element arranged on the flat substrate changes the traveling direction of the optical signal propagating in parallel with the plane of the integrated circuit substrate. As described above, this optical element has the same size, and it suffices to prepare only two types, that is, the state of the reflecting surface is total reflection or semi-reflection.
With these, it is possible to easily divide the optical signal and change the route. As described above, since the number of types of optical elements is small and a large number of parts can be manufactured, the manufacturing cost can be reduced. Further, in the above description, the sizes of the optical elements are made uniform, but the size is not limited to this. However, if the sizes are made uniform, it is effective when the optical elements are mass-produced.

Although the simplest example has been described above, the optical element need not be a cube as shown in FIG. 1 (c). Needless to say, even if the rectangular parallelepiped optical element shown in FIG. By the way, in the above embodiment, for example, a mirror may be used to change the path of the optical signal. The reflection efficiency of the mirror is the state-of-the-art technology, and even with a wideband reflectance,
%, 100 in narrow band reflectance coated with a dielectric multilayer film
% Has been obtained.

A beam splitter is used to split the optical signal, but even in this beam splitter, the dielectric multilayer film causes almost no optical loss. Both can be formed by adhering a triangular prism whose bottom surface is a right-angled isosceles triangle so as to have a cubic shape, but even if the adhesive used for this bonding has about 1% of light absorption and reflection loss, An efficiency of 95% is obtained with 5 reflections and 90% with 10 reflections.

On the other hand, when the holographic optical element is used, the efficiency differs depending on the hologram format, but the maximum diffraction efficiency of the amplitude type (absorption type) is less than 10%. At present, it is difficult to obtain a diffraction efficiency of substantially 90% or more even if the phase type is used. Therefore, according to the above-mentioned embodiment, there is an advantage that the propagation loss of light is small as compared with the conventional optical connection using the holographic element.

Example 2. By the way, in the above embodiment, a simple example is used for the configuration of the transmission path of the optical signal in order to simplify the description, but the present invention is not limited to this. LD (light emitting element) that emits an optical signal and PD (light receiving element) that receives an optical signal
It is also possible to correspond to an integrated circuit board in which a larger number of are arranged. It is also possible to branch three or more optical signals.

FIG. 3 is a plan view showing the configuration of the flat substrate and the optical element arranged thereon according to the second embodiment of the present invention. In the figure, the optical elements 3a-1 to 3a-9 arranged on the flat substrate 2 are the same as the optical elements 3a-1 to 3a-3 in FIG.
b-1 to 3b-4 are the same as the optical element 3b-2 in FIG. The optical element 3c-1 is an optical element whose semi-reflective surface has a transmission amount: reflection amount = 1: 2.

Optical element 3a-1 and optical element 3a-2
LDs are respectively arranged on the integrated circuit substrate facing the positions of the optical elements 3a-1 and 3 having the right-angle reflection function.
It is incident on a-2. First, the optical signal incident on the optical element 3a-1 has its course changed to a right angle and is incident on the optical element 3c-1 which branches the optical signal.

One of the optical signals split in two directions orthogonal to each other by the optical element 3c-1 is incident on the optical element 3a-3 as it is, and its course is changed in a direction perpendicular to the flat substrate 2, so that it is not shown. The light enters the PD, which is the signal light receiving unit of the integrated circuit board. The other exiting the optical element 3c-1 is the optical element 3
It is incident on b-1 and is further branched into two. The optical elements 3a-4 and 3a-5 change the path in a direction perpendicular to the flat substrate 2, and the light is incident on the corresponding PD on the integrated circuit substrate.

The optical signal emitted from the other LD is incident on the optical element 3a-2, the course of which is changed to a right angle, and then incident on the optical element 3b-2. Then, the optical element 3b-2 splits the optical signal going straight and the signal light whose traveling direction is changed by 90 °.
It is incident on 3b-3. Then, each of the incident optical signals is branched again and is incident on the optical elements 3a-8, 3a-9 and the optical elements 3a-6, 3a-7. Then, in the optical elements 3a-6, 3a-7, 3a-8, 3a-9, the incident optical signal is changed its course in a direction perpendicular to the surface of the flat substrate 2 and is transmitted to the corresponding PD on the integrated circuit substrate. Incident.

By the way, in this embodiment, the optical signals branched by the optical element 3b-2 are branched again. Therefore, at the time of reaching the PD on the integrated circuit substrate, the intensity of the original optical signal is about ¼. For this reason, it is preferable that the LD that transmits an optical signal to the optical element 3a-2 has a higher optical signal output intensity.

Further, in this embodiment, the optical element 3
The optical signal branched at c-1 has its path changed by 90 ° and is branched again at the optical element 3b-1. However, the straight-ahead component is not further branched. For this reason,
In the optical element 3c, as described above, the semi-reflective surface has the transmission amount: reflection amount = 1: 2, and the optical elements 3a-3 to 3a-5 are used.
The intensity of the emitted optical signal is made more uniform.

Here, the amount of light transmitted through the optical element 3c: the amount of reflection =
If the ratio is 1: 1, the optical signals emitted from the optical elements 3a-3 to 3a-5 become non-uniform in intensity, and the optical elements 3a-4,
The intensity of the optical signal emitted from 3a-5 becomes about 1/4 of the original intensity. However, as described above, since the semi-reflective surface has the transmission amount: reflection amount = 1: 2, the intensity of the optical signal emitted from the optical elements 3a-3 to 3a-5 is
It becomes about one-third of the original optical signal. Therefore, the amount of increase in the original signal intensity can be reduced as compared with the case where the original optical signal becomes one-fourth.

As described above, according to the second embodiment, the mirror, the half mirror and the beam splitter are used,
Optical elements having the same size and shape are used.
Therefore, similarly to the first embodiment described above, it is possible to cope with optical signal transmission through various routes without increasing the manufacturing cost.

Example 3. By the way, in the above embodiment, a cubic or rectangular parallelepiped optical element having a reflecting surface on the diagonal surface is used, but the present invention is not limited to this. As an optical element for changing the path of an optical signal, a triangular prism having a right angled isosceles triangle made of a transparent material as a bottom surface may be used. Then, the reflecting surface is formed on the flat surface having the largest area among the side surfaces of the triangular prism. 4A and 4B are a plan view and a cross-sectional view showing a configuration of a flat substrate and an optical element arranged on the flat substrate in the third embodiment of the present invention using the triangular prism-shaped optical element.

In the figure, on the flat substrate 2, similar to the above, on the lattice points of the virtually arranged lattice, the above-mentioned triangular prism-shaped optical elements 3d-1 to 3d-3, 3e- are formed.
1, 3e-2 are arranged. In addition, 3b-2 is a cubic optical element and is the same as that of FIG. The path of the optical signal due to the arrangement of these optical elements is the same as that shown in FIG.

That is, the optical signal emitted from the LD (not shown in FIG. 4) enters the optical element 3d-1 perpendicularly to the flat substrate 2 and is reflected by the reflection surface thereof to form the flat substrate 2. Change course in parallel. The optical signal that is parallel to the surface of the flat substrate 2 is incident on the optical element 3e-1, changes its direction by 90 °, and is incident on the optical element 3b-2. Optical element 3b-2
The optical signal incident on is split into an optical signal that travels straight on the semi-reflective surface and an optical signal that changes the direction by 90 °.

Here, the optical signal traveling straight is the optical element 3e.
At −2, the direction is changed by 90 ° and the light is incident on the optical element 3d-3. At its reflection surface, the direction of travel is changed by 90 ° with respect to the plane of the flat substrate 2 and then incident on a PD (not shown) arranged thereon. To do. The optical signal whose traveling direction is changed by 90 ° by the optical element 3b-2 is incident on the optical element 3d-2, whose traveling direction is changed by 90 ° with respect to the plane of the flat substrate 2, It is incident on a PD (not shown) to be arranged. As described above, the optical connection from the LD to the PD on the integrated circuit substrate is realized.

In this embodiment, the triangular prism-shaped optical element 3d-is provided at a position where the traveling direction of the optical signal is changed.
1-3d-3, 3e-1, and 3e-2 were used. Among them, the optical elements 3d-1 to 3d-3 make an optical signal entering the flat substrate 2 parallel to the plane of the flat substrate 2 or an optical signal traveling on the plane of the flat substrate 2 in parallel. Are used to emit light in a direction perpendicular to the plane of the flat substrate 2. At this time, the optical signal is arranged to be reflected directly from the air on the slope. In addition, the optical element 3e-1,
3e-2 was used to change the traveling method of the optical signal on the plane of the flat substrate 2, and was arranged using total internal reflection.
From the viewpoint of standardization of optical elements, all the triangular prism shapes have the same shape and the same size, and all the slopes may be preliminarily coated with a mirror and the placement may be changed appropriately.

By the way, in this embodiment, at the lattice point for branching the optical signal, the optical element 3b-
2 is used. By using the optical element 3b-2, the transmitted optical signal and the reflected optical signal do not change the refractive index of the medium that is emitted from the half mirror forming surface. Here, when a half mirror is formed on the reflecting surface of the optical element 3d-1, it works almost the same as the optical element 3b-2, but if this is used, the half mirror surface is used as a boundary for the transmitted optical signal. Moreover, the refractive index of the medium changes, and the course of the change occurs. Therefore, when branching an optical signal, it is better to use an optical element having a semi-reflecting surface included therein.

As described above, in this embodiment, two kinds of optical elements having different shapes are used. However, since the triangular prism-shaped optical parts are easier to manufacture, the manufacturing cost is reduced. From the aspect, it may be more advantageous than the above embodiment.

Example 4. In the third embodiment, the triangular prism-shaped optical element having the right-angled isosceles triangle as the bottom is used, but the present invention is not limited to this. FIG. 5 is a perspective view showing the shape of the optical element in the fourth embodiment. In FIGS. 5A and 5B, the bases are 60 ° and 30 °.
It is a triangular prism-shaped optical element that is a right-angled triangular shape composed of 90 ° and 90 °.

By using such an optical element, it is possible to cope with an optical signal which is incident on the flat substrate which propagates the optical signal at a non-vertical angle. For example, even if the LD of the integrated circuit substrate is not disposed directly above the optical element that is the entrance of the optical signal that makes the incident optical signal parallel to the flat substrate plane, and the positional relationship between them is shifted, An optical element can be used to make an incident optical signal parallel to the flat substrate plane.

This is the light emitting element LD or the light receiving element P.
It may be possible to deal with a case where Ds are densely arranged and the optical element cannot be arranged directly below each element. Then, the angle of the hypotenuse with respect to the orthogonal sides of the right-angled triangle of the bottom surface of the triangular prism is
It may be set between 30 ° and 60 ° according to each arrangement. In this case, if the angles are not continuously variable but are set, for example, in increments of 5 ° and are manufactured separately, the number of types of optical elements does not increase excessively. The incident angle of the optical signal to the flat substrate is within 30 ° from the perpendicular to the flat substrate surface in order to suppress the distortion of the beam shape caused by the oblique flight of the optical signal and the loss of the light intensity due to it. It should be so.

FIG. 5C shows an optical element having a pentagonal columnar bottom surface. In this case, side AB and side EA
Are equal in length and orthogonal. Also, side BC and side ED
The extension lines intersect at an angle of 45 ° C. Also, the corner ABC and the corner DEA are equal. Then, a reflecting surface is formed on each of the rectangular surfaces that are in contact with the side BC and the side DE.

With this optical element, an optical signal incident from the rectangular surface in contact with the side AE is reflected by the rectangular surface in contact with the side BC and is incident on the rectangular surface in contact with the side ED. The reflected optical signal is reflected by the rectangular surface in contact with the side ED and emitted from the rectangular surface in contact with the side AB. Then, in this optical element, the path of the optical signal that is incident from the rectangular surface that is in contact with the side AE and is reflected by the rectangular surface that is in contact with the side BC and the optical signal that is emitted from the rectangular surface that is in contact with the side AB The path is always 90 °. In this way, since the optical signal is bent at a right angle regardless of the incident angle, there is an advantage that the positional accuracy of the arrangement is not required when using this optical element.

Example 5. By the way, in the above embodiment, the optical elements arranged at the adjacent lattice points are not in contact with each other, but the present invention is not limited to this. Figure 6
FIG. 8 is a plan view showing a configuration of a flat substrate and an optical element arranged on the flat substrate according to a fifth embodiment of the present invention. In the figure, the optical element 3f-1 arranged on the flat substrate 2
3f-9 are optical elements 3a-1 to 3a- in FIG.
9, and the optical elements 3g-1 to 3g-4 are the same as the optical elements 3b-1 to 3b-4. The optical element 3h-1 is similar to the optical element 3c-1 in FIG. 3, and its semi-reflective surface has an amount of transmission: amount of reflection = 1: 2. The arrangement of the virtual lattices of the optical elements on the flat substrate 2 at the lattice points is also the same as in FIG.

However, the optical element in this embodiment is
One side thereof has a cubic shape equal to the length of one side of the virtual lattice on the flat substrate 2. That is, for example, the optical elements 3f-8 and 3f-9 are adjacent to the optical element 3g-4, respectively. As in this embodiment, the optical element may have a size equal to or smaller than an imaginary lattice formed on the flat substrate, and as shown in FIG.
Even if optical elements having the same size as the grating are used and they are in contact with each other when they are adjacent to each other, the same effect as in the third embodiment can be obtained.

Example 6. By the way, when the size of the optical element is set to be the same as that of the virtually formed grating as in the fifth embodiment, the optical elements arranged at the adjacent lattice points are in contact with each other as described above. Become. For example, in FIG. 6, the optical elements 3f-8 and 3f-9 are adjacent to the optical element 3g-4, and these three optical elements can be regarded as one optical element. FIG. 7 is a plan view showing the configuration of the flat substrate and the optical elements arranged thereon in the sixth embodiment.

In the figure, the same reference numerals are the same as in FIG. Here, reference numeral 3i is an optical element in which the optical element 3f and the optical element 3g in FIG. 6 are combined into one optical element. The optical element 3i is a cube-shaped optical element having a function of changing the course of an optical signal between a state perpendicular to the plane of the flat substrate 2 and a state parallel to the plane, and a plane parallel to the plane of the flat substrate 2 This is a combination of a cubic optical element having a function of branching an optical signal.

By preparing one optical element in a state where such cubic optical elements are combined, as shown in FIG.
The configuration for propagating an optical signal as shown in can be configured with an optical element having a smaller number of components. For example, in FIG.
In the configuration of FIG. 7, 14 optical elements are used, but in the configuration of FIG. 7, only 8 optical elements are needed. As a result, although the number of types of components is increased, a mass of elements having the same structure can be produced in advance with high accuracy, and the step of adhering these optical elements and the flat substrate can be simplified. Then, as shown in FIG.
Especially when the optical element layout of the flat substrate for optical connection is such that one type of unit component can be used in many places, it is highly likely to be advantageous in terms of manufacturing cost.

FIG. 8 is a plan view showing another example of an optical element unit in which a plurality of cube-shaped optical elements described above are connected to form one optical element. Figure 8
(A) is an optical element that splits an optical signal in different directions on adjacent lattice lines in parallel. FIG. 8B shows an optical element that changes the path of an optical signal in the same direction on parallel and adjacent grid lines. FIG. 8C shows an optical element that splits an optical signal in four different directions on parallel and adjacent grid lines.
8D is an optical element for branching an incident optical signal and changing the path of the optical signal in opposite directions on parallel grid lines on both sides of the path and on both sides of the path ahead of the path. Is.

[0062]

As described above, according to the present invention, at least three planes orthogonal to each other and a plane parallel to any one of these planes are provided, and at the same time, two planes facing each other are orthogonal to each other. Then, by arranging a reflective optical element made of a transparent body having a reflective surface set at a predetermined angle with the other surface on a flat substrate, the integrated circuits are optically connected. In addition, at least it is composed of three surfaces that are orthogonal to each other and a surface that is parallel to any one of them, and in addition, it is orthogonal to two surfaces that are parallel to each other and is set to a predetermined angle with other surfaces. The branch optical element made of a transparent material having a semi-reflecting surface is also arranged on the flat substrate to optically connect the integrated circuits.

For this reason, since an optical signal is propagated on the flat substrate in parallel with the flat surface, the distance between the integrated circuit substrate and the flat substrate is expanded even if the integrated circuits optically connected are long distances. There is no need, and there is an effect that the mounting dimension does not increase. The reflecting optical element and the branching optical element arranged on the flat substrate can be configured by prisms, mirrors, half mirrors, etc., and since a diffractive element such as a hologram is not used, the propagation loss of light is small and the signal transmission efficiency is high. high. In addition, the type of each optical element is limited, and the shape and size are standardized. Then, a virtual lattice is set on the flat substrate, and the optical element is installed only on the lattice points. For these reasons, the optical transmission path can be simply optimized, and the manufacturing cost and the development cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a plan view of the flat substrate 2 of FIG. 1, optical elements 3a-1 to 3a-3 arranged on the flat substrate 2, and an optical element 3b'-.
It is a top view which shows the structure of 1,3b-2,3b'-3.

FIG. 3 is a plan view showing a configuration of a flat substrate and an optical element arranged on the flat substrate according to a second embodiment of the present invention.

4A and 4B are a plan view and a cross-sectional view showing the configuration of a flat substrate and an optical element arranged thereon in the third embodiment of the present invention using the triangular prism-shaped optical element.

FIG. 5 is a perspective view showing the shape of an optical element in Embodiment 4 of the present invention.

FIG. 6 is a plan view showing a configuration of a flat substrate and an optical element arranged thereon according to a fifth embodiment of the present invention.

FIG. 7 is a plan view showing a configuration of a flat substrate and an optical element arranged thereon according to a sixth embodiment of the present invention.

FIG. 8 is a plan view showing an example of an optical element unit in which a plurality of cube-shaped optical elements are joined together to form one optical element.

FIG. 9 is a perspective view showing a configuration of a conventional chip-to-chip interconnection using light.

FIG. 10 is a cross-sectional view showing a configuration of a conventional chip-to-chip interconnection using light.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Integrated circuit board, 1a ... Integrated circuit chip, 1b ... Laser diode (LD), 1c ... Photodiode (P
D), 2 ... Flat substrate, 3a, 3b ... Optical element, 4 ... Solder bump.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Kuroki Tsutomu, 1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (72) Inventor, Katsuyuki Machida 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (56) Reference JP-A-3-248258 (JP, A) JP-A-3-178230 (JP, A) Special Table 6-507533 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 27/00 H04B 10/02 H04B 10/28

Claims (6)

(57) [Claims] 1. A surface at least composed of three planes orthogonal to each other and a plane parallel to any of these planes, and in addition, it is orthogonal to two planes facing each other and set at a predetermined angle with respect to the other planes. First and second reflective optical elements made of a transparent body having a reflective surface, a flat substrate having a flat surface on which the first and second reflective optical elements are arranged, and facing the flat substrate An integrated circuit board on which a first integrated circuit having a light emitting portion for outputting an optical signal for optical connection and a second integrated circuit having a light receiving portion for inputting an optical signal for optical connection are arranged on a plane. Wherein the first reflective optical element uses an optical signal emitted from the light emitting unit of the first integrated circuit as an optical path parallel to a flat surface of the flat substrate, and the second reflective optical element includes: The optical path is parallel to the flat surface of the flat substrate. That an optical signal, the second by changing to be incident on the light-receiving portion of the integrated circuit, optical integrated circuit, characterized by that the optical connection between the first and second integrated circuits. 2. The optical connection integrated circuit according to claim 1, wherein the optical connection integrated circuit is composed of at least three planes orthogonal to each other and a plane parallel to any one of the planes, and is orthogonal to two planes facing each other in parallel. A third reflective optical element comprising a transparent body having a reflective surface set at a predetermined angle with the other surface and changing the direction of the optical path by 90 ° in a plane parallel to the flat surface of the flat substrate. A predetermined lattice point of a virtual lattice such that all points on the flat surface of the flat substrate where the first and second reflective optical elements are arranged are on lattice points, An optical connection integrated circuit in which the third reflective optical element is arranged to optically connect the first and second integrated circuits. 3. The optical connection integrated circuit according to claim 1 or 2, comprising at least three planes orthogonal to each other and a plane parallel to any one of the planes, and additionally including two planes facing each other in parallel. A branch optical element that is orthogonal to the other surface and has a semi-reflective surface that transmits a part of incident light and is set at a predetermined angle with the other surface; and on the flat surface of the flat substrate, By arranging the branching optical element at a predetermined lattice point of a virtual lattice such that all the points where the first and second optical elements are disposed are on the lattice point, the first and second integrated circuits are integrated. An optical connection integrated circuit characterized in that the circuits are optically connected. 4. The optical connection integrated circuit according to claim 1, wherein the first to third reflective optical elements and the branch optical element are
An optical connection integrated circuit, the external shape of which is a rectangular parallelepiped, and two surfaces orthogonal to the reflecting surface or the semi-reflecting surface are square. 5. The optical connection integrated circuit according to claim 4, wherein a plurality of the first to third reflective optical elements and a plurality of branch optical elements are combined into one unit. Integrated circuit. 6. The optical connection integrated circuit according to claim 1, wherein the first to third reflective optical elements and the branch optical element are
An optical connection integrated circuit characterized in that its size is standardized.