JP2002090571A - Optical bus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical bus whose production is simple and which has high signal transmission efficiency. SOLUTION: The optical bus 100 where signal light is made incident from one end and emits from the other end, is provided with a optical transmission layer 2 which transmits the signal light from the one end toward the other end and a light shielding layer 4 which prevents interfusion of signal light between two adjacent optical transmission layers. The optical transmission layer 2 and the light shielding layer 4 are constituted by laminating them alternately, and a space is formed between the optical transmission layer 2 and the light shielding layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical bus, and more particularly, to an optical bus which has a high signal light transmission efficiency and is easy to manufacture, like the conventional optical bus.

[0002]

2. Description of the Related Art With the development of very large scale integrated circuits (VLSI),
The circuit functions of circuit boards (daughter boards) used in data processing systems have been greatly increased. As the number of signal connections to each circuit board increases as circuit functions increase, a data bus board (motherboard) that connects each circuit board with a bus structure requires a parallel architecture that requires a large number of connectors and connection lines. Has been adopted, and the operation speed of a parallel bus has been improved by promoting parallelization by increasing the number of connection lines and miniaturization.

However, in the data bus board, the processing speed of the system may be limited by the operation speed of the parallel bus due to a signal delay caused by a capacitance between connection lines or a connection line resistance. In addition, electromagnetic noise (EMI: Electromagnetic Inte
rference) is also a major constraint on improving the processing speed of the system.

In order to solve such a problem and to improve the operation speed of the parallel bus, use of an in-system optical connection technique called optical interconnection has been studied. For an overview of optical interconnection technology, see U. Sadaji, `` Academic Lecture Meeting on Circuit Packaging, 15C01, '' p. 201-202, and H.
Tomimuro et al., "Packaging Technology for OpticalI
As described in “Nterconnects”, IEEE Tokyo No. 33 (1994), pp. 81-86, various forms have been proposed depending on the configuration of the system.

[0005] Among various types of optical interconnection technologies proposed in the past, Japanese Patent Application Laid-Open No. 2-41042 discloses an optical data transmission system using a high-speed, high-sensitivity light emitting / receiving device applied to a data bus. Examples are disclosed in which light emitting / receiving devices are placed on both front and back of each circuit board, and light emitting / receiving devices on adjacent circuit boards built into the system frame are spatially optically coupled. A serial optical data bus for loop transmission between circuit boards has been proposed.

In the serial optical data bus, a certain 1
The signal light sent from one circuit board is converted to light / electricity by an adjacent circuit board, and the electric /
Each circuit board is sequentially arranged in series, such as being optically converted and then sending signal light to the next adjacent circuit board, and repeated on the circuit board by optical-to-electrical conversion and electrical-to-optical conversion. It is transmitted between all installed circuit boards. For this reason, the signal transmission speed depends on the light / electric conversion speed and the electric / light conversion speed of the light emitting / receiving device arranged on each circuit board, and is restricted by the speed.

[0007] Further, since data transmission between the circuit boards uses optical coupling via a free space by a light emitting / receiving device arranged on each circuit board, both sides of an adjacent circuit board are used. The optical alignment of the light emitting / receiving devices arranged in the device is performed, and all the circuit boards need to be optically coupled.

Further, since the optical data transmission lines are coupled via free space, interference (crosstalk) between adjacent optical data transmission lines is caused.
It is expected that data transmission failure will occur.

Further, it is expected that data transmission failure will occur due to scattering of signal light due to the environment in the system frame, for example, dust.

Furthermore, since the circuit boards are arranged in series, if any one of the boards is removed, the connection is interrupted there, and an extra circuit board is required to compensate for the disconnection. That is, there is a problem that the circuit board cannot be freely inserted and removed, and the number of circuit boards is fixed.

Another system for transmitting data between circuit boards using free space is disclosed in Japanese Patent Application Laid-Open No. 61-196210.

[0012] The system disclosed in the above-mentioned publication includes a plate opposed to a light source having two parallel surfaces,
In this method, a circuit is composed of a diffraction grating and a reflective element arranged on the surface of a plate, and optically couples between circuit boards via an optical path using free space.

However, in the above-mentioned method, light emitted from one point can be connected only to a fixed point, and all the circuit boards cannot be exhaustively connected like an electric bus. Since a free space is used, a complicated optical system is required, and alignment is difficult, so crosstalk between adjacent optical data transmission lines occurs due to misalignment of optical elements, resulting in poor data transmission. Is expected to occur, and the connection information between the circuit boards is determined by the diffraction grating and the reflective element arranged on the plate surface, so the circuit board cannot be freely inserted and removed, and the expandability is low. There are various problems such as things.

[0014] As means for solving these problems, a circuit board is arranged around the parallel reflectors with high reflectivity, light from the light emitting element is radiated to the whole space, and between the parallel reflectors with high reflectivity. A system that transmits and receives optical signals by propagating in confined free space, that is, by using a high-reflectance parallel reflector as an optical bus, has been proposed (Tetsuoki An, Taku Minemoto, "High Reflection Wavelength Division Multiplexing Optical Interconnection between Boards Using Percentage Laminates ", Optics, Vol. 24, No. 9, 1995
4 (50) -580 (56), Akira Tetsuko, Minemoto Taku, "The architecture of a computer dedicated to fast Fourier transform using wavelength division multiplexed optical interconnection", Optics Vol. 25, No. 6, 1996
Years), p337 (43) -344 (50)).

In Japanese Patent Application Laid-Open No. 9-270752,
2. Description of the Related Art An optical bus for transmitting a signal light by diffusing and propagating the signal light in a flat light guide path has been proposed.

[0016]

In the optical bus, cladding layers having a lower refractive index than the light guide are provided on both sides of the light guide to confine light in the light guide, and these are laminated. Thus, the number of bits of the optical bus is increased ((a) in FIG. 11).

In the optical bus, a light-shielding layer is provided to suppress crosstalk between the light guide paths, and the light-shielding layers and the light guide paths are alternately stacked and adhered to each other, so that the process is complicated. There was a problem. If the light guide path is laminated with the light shielding layer without providing the cladding layer in order to simplify the process, there is a problem that light is absorbed by the light shielding layer and a signal cannot be transmitted. That is, as shown in FIG. 11B, the light guide path A is provided with the cladding layer A2 and the light shielding layer B is provided.
When the signal light S is laminated, the signal light S is propagated by being totally reflected at the interface between the light guide path A and the clad layer A2. However, as shown in FIG. When the light beam S was directly laminated on the light shielding layer B without being provided, the signal light S was absorbed by the light shielding layer B and could not be transmitted.

The present invention has been made to solve the above-mentioned technical problems, and a laminate is manufactured by a simple process.
An object of the present invention is to provide an optical bus for performing signal transmission with less loss.

[0019]

According to a first aspect of the present invention, there is provided an optical bus in which a signal light is inputted from one end and outputted from the other end, and the signal light is transmitted from the one end to the other end. A light transmission layer, and a light shielding layer for preventing signal light from being mixed between two adjacent light transmission layers,
The light transmission layer and the light shielding layer are alternately laminated,
An optical bus, wherein a gap is formed between the light transmission layer and the light shielding layer.

In the optical bus, an air layer exists between the light transmission layer and the light shielding layer, and the material forming the light transmission layer has a higher refractive index than air.
Therefore, the signal light incident on the light transmission layer is totally reflected at the interface between the light transmission layer and the air layer, returns to the inside of the light transmission layer, and propagates inside the light transmission layer with high efficiency.

Therefore, it is not necessary to provide a clad layer having a smaller refractive index than the optical transmission layer on the surface of the optical transmission layer, so that it is easier to manufacture than a conventional optical bus.

According to a second aspect of the present invention, each of the light transmission layer and the light shielding layer is a plate-like member, and at least one of the light transmission layer and the light shielding layer has a convex portion on the surface. And an optical bus in which the light transmission layer and the light shielding layer are bonded at the convex portion.

The optical bus is particularly easy to manufacture because the optical transmission layer and the light-shielding layer can be manufactured by alternately superposing the light transmission layers and the light-shielding layers, aligning the ends thereof, and bonding them to each other at the convex portions.

According to a third aspect of the present invention, the convex portion is
The present invention relates to an optical bus which is a band-shaped projection provided on the one end side and the other end side of the light transmission layer or the light shielding layer.

In the optical bus, a convex portion can be formed, for example, by bonding a band-shaped member to the portion in the light transmission layer or the light shielding layer, or by forming the convex portion by injection molding. Therefore, the formation of the convex portion is particularly easy.

According to a fourth aspect of the invention, when transmitting an optical signal, an input optical fiber for inputting an optical signal to the optical transmission layer is connected to the one end of the optical transmission layer.
An optical bus in which an output optical fiber for extracting signal light emitted from the optical transmission layer is connected to the other end side of the optical transmission layer, wherein the convex portion has the input optical fiber on the one end side. The signal light non-coupling is formed in the signal light non-arriving portion that is not irradiated with the signal light incident from the optical signal transmission device, and the other end of the signal light non-coupling is a range where the output light that has propagated in the optical transmission layer cannot enter the output optical fiber The present invention relates to an optical bus formed in a section.

In the optical bus, a convex portion is formed on the signal light non-arrival portion and the signal light non-coupling portion, and an optical transmission layer and a light shielding layer are bonded at the convex portion. Then, neither the signal light non-arrival portion nor the signal light non-coupling portion absorbs the signal light.

Therefore, the optical bus is characterized in that the signal light is not absorbed by the bonding portion, and the loss due to the absorption of the signal light is particularly small.

According to a fifth aspect of the present invention, the convex portion is
The present invention relates to an optical bus having a planar shape of a triangular prism whose apex faces the center of the optical transmission layer.

The optical bus has a feature that the area of the bonding portion for bonding the light transmission layer and the light shielding layer is large, so that the light transmission layer and the light shielding layer can be firmly bonded.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment FIGS. 1 and 2 show an example of an optical bus according to the present invention. In FIG. 1, a) shows the optical bus viewed obliquely from above, and b) shows the signal light path in the optical bus.

As shown in FIG. 1, in an optical bus 100 according to the first embodiment, an optical transmission layer 2 formed in a rectangular plate or sheet shape and an optical transmission layer 2 formed in a rectangular plate or sheet shape are also formed. The light shielding layers 4 are alternately laminated.

As shown in FIG. 2, a short columnar convex portion 2A is formed on both surfaces near each vertex of the optical transmission layer 2, and the light transmission layer 2 is shielded from light at the top surface of the convex portion 2A. Layer 4
And glued.

An adhesive may be used for bonding the light transmission layer 2 and the light shielding layer 4 or may be bonded by heat fusion. Further, the light transmission layer 2 and the light shielding layer 4 do not necessarily need to be bonded to each other, and may be fixed by being clamped in a thickness direction by a clamp or the like.

The thickness of the light transmission layer 2 and the light shielding layer 4 is generally in the range of 0.5 to 2 mm, but the thickness is not particularly limited. The thickness of the light transmission layer 2 is
Is the thickness of the portion where the convex portion 2A is not provided.

The height of the convex portion 2A formed on the light transmission layer 2 is generally in the range of 0.05 to 0.5 mm. It is sufficient that the height does not make contact, and it can be determined according to the dimensions of the light transmission layer 2 and the light shielding layer 4. Further, the shape of the convex portion 2A is not limited to a short columnar shape.

FIG. 3 shows a modification of the convex portion 2A in the light transmission layer 2. In the optical transmission layer 2 shown in FIG.
A is a projection formed in a band shape on both sides along a pair of short sides in the optical transmission layer 2 shown in (a), and a pair of long projections in the optical transmission layer 2 shown in (b). It is a projection formed in a belt shape on both sides along the side. Then, in the optical transmission layer 2 shown in (c), convex portions 2A having a substantially square planar shape are formed on both surfaces near each vertex of the optical transmission layer 2, and the optical transmission layer 2 shown in (d) is formed. In (2), convex portions 2A having a rhombic planar shape are formed on both surfaces near each vertex of the optical transmission layer 2. The convex portion 2A may be formed in a spherical shape, a truncated cone shape, a truncated pyramid shape, or the like.

The convex portion 2A may be formed integrally with the light transmission layer 2 or may be formed separately from the light transmission layer 2 and may be formed by an appropriate means such as adhesion or heat fusion. May be adhered to.

The optical transmission layer 2 can be formed of a light-transmitting material that is substantially transparent to signal light to be transmitted on the optical bus 100. Specific examples of the light-transmitting material include polymethyl methacrylate (PMMA), polycarbonate, amorphous polyolefin such as poly-4-methylpentene-1 and ethylene-propylene copolymer, and vinylidene fluoride and tetrafluoroethylene. Transparent plastic materials such as fluorine-based resins, and transparent glass-based materials such as quartz, quartz glass, fluoride-based glass, aluminosilicate glass, phosphate glass, and fluorophosphate glass are exemplified. Note that a light-transmitting diffusion sheet may be provided on the surface of the light transmission layer 2 on the side to which the input optical fiber 10 described later is connected. The diffusion sheet,
Preferably, the light is diffused in the width direction but not in the thickness direction.

The light-shielding layer 4 can be formed of a non-light-transmitting material that does not substantially transmit the signal light. Specifically, a light-shielding plastic material obtained by adding a light-shielding pigment such as carbon black to the transparent plastic material is used. Can be formed. In addition, as the light-shielding layer 4, a black plate-like member in which the surface of a plate-like member formed of the light-transmitting material is colored black can be used.

In the optical bus 100, FIGS.
As shown in the figure, an air layer A is provided between the light transmission layer 2 and the light shielding layer 4.
Since ir intervenes, both surfaces of the light transmission layer 2 form an interface with the air layer Air. Here, the light transmission layer 2
Since the light-transmitting material forming the light-transmitting material generally has a refractive index larger than that of air, the signal light that has entered the inside of the light transmission layer 2 from one end of the one light transmission layer 2 is the same as that in FIG. As shown in b), the light is totally reflected on any surface of the light transmission layer 2 and propagates in the light transmission layer 2. At this time, the convex portion 2A
Is absorbed by the convex portion 2A, but the ratio is only a small part of the entire signal light, so that the absorption loss of the signal light is extremely small.

In the optical bus 100 according to the first embodiment, an input optical fiber 10 for inputting signal light is connected to one end face of the optical transmission layer 2 and the other end face of the optical transmission layer 2 is connected to
An optical signal can be transmitted by connecting an output optical fiber 20 for extracting a signal light emitted from the optical transmission layer 2. Hereinafter, the end face on the side where the input optical fiber 10 is connected is referred to as an incident side end face 2B, and the end face on the side where the output optical fiber 20 is connected is referred to as an output side end face 2C. The incident side end face 2B and the exit side end face 2C correspond to one end side and the other end side in the optical transmission layer provided in the optical bus of the present invention, respectively. FIG. 4 shows an example in which the input optical fiber 10 is connected to the input side end face 2B of the optical transmission layer 2 and the output optical fiber 20 is connected to the output side end face 2C.

As shown in FIG. 4, the input optical fiber 10 has, at the end connected to the incident side end face 2B, the position of the incident side end face 2B of the optical transmission layer 2 and the coupling end face of the optical fiber 10. It is fixed to a positioning block 12 for adjusting the position. The positioning block 12 has an optical fiber insertion hole 12A through which the input optical fiber 10 passes.
And the input optical fiber 10 is
Each optical transmission layer 2 is put together and inserted into the optical fiber insertion hole 12A.

As shown in FIG. 4, the output optical fiber 20 is connected to the output side end face 2C of the optical transmission layer 2 at the end connected to the output side end face 2C.
Are fixed to a positioning block 22 for coupling the two. Like the positioning block 12, the positioning block 22 has an optical fiber insertion hole 22A through which the output optical fiber 20 passes.
However, the output optical fibers 20 are grouped for each optical transmission layer 2 and inserted into the optical fiber insertion hole 22A.

The diameter of the input optical fiber 10 and the output optical fiber 20 may be the same as the thickness of the optical transmission layer 2 as shown in FIG. Good. However, the difference between the diameter of the input optical fiber 10 and the output optical fiber 20 and the thickness of the light transmission layer 2 is preferably within 10% of the thickness of the light transmission layer 2.

The positional relationship between the optical transmission layer 2 and the input optical fiber 10 and the output optical fiber 20 in the optical bus 100 connecting the input optical fiber 10 and the output optical fiber 20, and the signal light from the input optical fiber 10 is transmitted to the optical transmission layer FIG. 5 shows how the light enters the optical fiber 2 and how the signal light propagating through the optical transmission layer 2 enters the output optical fiber 20.

As shown in FIG. 5B, the outgoing light 10A is emitted from the opposite side of the connection side of the input optical fiber 10 at an angle determined by the numerical aperture (NA) of the input optical fiber 10. Here, when the diameter of the input optical fiber 10 is the same as the thickness of the optical transmission layer 2, when the output light 10A from the end face of the input optical fiber 10 enters the optical transmission layer 2 from the incident side end face 2B, the output light 10A 5 spreads in a triangular shape along the emission direction on the upper surface and the lower surface of the optical transmission layer 2 as shown by 10B in FIG. Therefore, as shown in FIG. 5 (c), in the vicinity of the incident side end face 2B on the upper surface and the lower surface of the optical transmission layer 2, as shown in FIG. The signal light non-arrival portions 2D, which are triangular shapes that are enlarged and are not irradiated with the signal light 10A, are formed corresponding to the input optical fibers 10, respectively.

Similarly, the output side end face 2 of the optical transmission layer 2
Also in C, since the angle of light incident on the output optical fiber 20 is determined by the numerical aperture (NA) of the output optical fiber 20,
As shown in FIG. 5D, the signal light non-coupling portion 2E, which is a range where the signal light propagated through the optical transmission layer 2 cannot enter the output optical fiber 20, is provided on the upper and lower surfaces in the vicinity of the output side end face 2C. The output optical fiber 20 is formed in a triangular shape extending toward the end face. The signal light non-coupling portions 2E are also formed corresponding to the respective output optical fibers 20.

In the optical bus according to the first embodiment, as described above, the signal light incident on the optical transmission layer 2 propagates inside the optical transmission layer 2 while being totally reflected on both surfaces of the optical transmission layer 2. Therefore, it is not necessary to provide clad layers on both surfaces of the light transmission layer 2. The light transmission layer 2 can be easily formed from a transparent plastic material by injection molding or the like. The light-shielding layer 4 can be easily formed by injection molding, for example, from a mixture of the transparent plastic material and carbon black. Then, the obtained light transmission layer 2 and light shielding layer 4
By alternately stacking and bonding, the optical bus according to the first embodiment can be created.

Therefore, the optical bus according to the first embodiment is different from the optical bus shown in FIG.
Although it is comparable in efficiency to the conventional optical bus shown in FIG. 1, it is much easier to manufacture and can be manufactured at low cost.

2. Second Embodiment In the optical bus 100 according to the first embodiment, the signal light non-arrival part 2D and the signal light non-coupling part 2 in the optical transmission layer 2
If a bonding region with the light-shielding layer 4 is provided in E, the signal light does not reach the bonding region, so that there is no loss of the signal light due to absorption.

Therefore, in the optical bus 100 according to the first embodiment, the signal light non-arrival section 2 in the optical transmission layer 2
D and the signal light non-coupling portion 2E are each formed with a convex portion 2A.
In this case, it is possible to eliminate the signal light absorption loss at the bonding portion with the light shielding layer 4.

FIG. 6 shows an example of an optical bus in which a convex portion 2A is formed in each of the signal light non-arrival portion 2D and the signal light non-coupling portion 2E of the optical transmission layer 2. 6, the same reference numerals as those in FIGS. 1 to 5 denote the same reference numerals as those in FIGS.
The same components as those shown in FIG.

The optical bus 102 according to the second embodiment is similar to the optical bus 102 shown in FIG.
As shown in FIG. 5, the light shielding layer 4 has five layers and the light transmission layer 2 has four layers, and the light shielding layers 4 and the light transmission layers 2 are alternately laminated.

FIG. 7A shows the planar shape of the light transmission layer 2.

As shown in FIG. 7A, in the optical transmission layer 2 provided in the optical bus 102, each of the signal light non-arrival portion 2D and the signal light non-coupling portion 2E has a vertex toward the center. An equilateral triangular convex portion 2A is formed. However, the convex portions 2A at both ends have a right-angled triangular plane shape obtained by cutting an equilateral triangle in half.

The light transmission layer 2 has a convex portion 2 having the above-mentioned shape.
At A, it is adhered to the light shielding layer 4.

Other shapes of the convex portion 2A in the light transmission layer 2 include a semicircular shape ((b) in FIG. 7) and a square shape ((b) in FIG. 7). (C) in FIG. 7 and a diamond shape ((d) in FIG. 7)
However, the shape is not limited to these, and includes, for example, a hemisphere, a truncated cone, a truncated pyramid, and the like.

FIG. 8 shows an example in which an optical fiber is connected to the optical bus 102 according to the second embodiment. 8, the same reference numerals as those in FIG. 4 indicate the same elements as those shown in FIG. 4 unless otherwise specified.

The positioning member 12 for fixing the input optical fiber 10 to the incident end face 2B of the optical transmission layer 2 and the positioning member 22 for fixing the output optical fiber 20 to the emission end face 2C of the optical transmission layer 2 are all shown in FIG. Has the same configuration and function as the positioning members 12 and 22 shown in FIG.

The relationship between the diameter of the input optical fiber 10 and the output optical fiber 20 and the thickness of the optical transmission layer 2 is also shown in FIG.
This is the same as the example shown in FIG.

As described above, the optical bus according to the second embodiment is provided with the adhesive area with the light shielding layer 4 in the area where the signal light does not reach in the optical transmission layer. In addition to the features of the above, there is a feature that the absorption loss of the signal light in the optical transmission layer is particularly small.

Further, as shown in FIG. 7, since the bonding region with the light shielding layer 4 is provided over the entire width of the light transmitting layer 2, the bonding between the light transmitting layer 2 and the light shielding layer 4 is further strengthened. It also has the feature that it can be done.

3. Third Embodiment Still another example of the optical bus according to the present invention is shown in FIG. FIG.
, The same reference numerals as those in FIGS. 1 to 5 indicate the same components as those shown in FIGS. 1 to 5, unless otherwise specified.

As shown in FIG. 9, the optical bus 104 according to the third embodiment is formed of a translucent material as described for the optical bus according to the first embodiment, and has a rectangular planar shape. And a plate-shaped light-shielding layer 8 formed of the non-translucent material described in the optical bus according to the first embodiment and having the same shape and dimensions as the optical transmission layer 6.
And are laminated on each other.

On both sides near each vertex of the light shielding layer 8,
A short columnar convex portion 8A is formed on both surfaces, and is bonded to the light transmission layer 6 on the top surface of the convex portion 8A.

For bonding the light transmitting layer 6 and the light shielding layer 8, an adhesive may be used, or they may be bonded by heat fusion. Furthermore, the light transmission layer 6 and the light shielding layer 8 do not necessarily need to be adhered to each other, and may be fixed by being clamped in the thickness direction by a clamp or the like.

The thicknesses of the light transmission layer 6 and the light shielding layer 8 are as shown in FIG.
In each of the examples shown in FIG. 1, the distance is 1 mm, but is generally in the range of 0.5 to 2 mm. However, the thicknesses of the light transmission layer 6 and the light shielding layer 8 are not particularly limited to the above ranges.

The thickness of the convex portion 8A formed on the light-shielding layer 8 is 0.1 mm in the example shown in FIG. 9, but the height is such that the light transmission layer 8 does not contact the light-shielding layer 6 at the center. It can be determined according to the dimensions of the light transmission layer 6 and the light shielding layer 8, and is generally in the range of 0.05 to 0.5 mm. The diameter of the convex portion 8A can be determined according to the width of the light transmission layer 6, that is, the width of the light shielding layer 8. For example, when the width is 8 mm, 1 mm is preferable. The shape of the protruding portion 8A is not limited to a short columnar shape, and may include a band shape along a short side or a long side. The convex portion 8A may have a substantially square or rhombic planar shape, and may be formed in a spherical shape, a truncated cone shape, a truncated pyramid shape, or the like.

In the optical bus 104 according to the third embodiment, it is not necessary to form a convex portion on the optical transmission layer 6 as described above. Materials that are difficult to injection-mold, such as the transparent glass-based materials described in the section, can also be suitably used. Here, the transparent glass material generally absorbs less light than a transparent plastic material such as PMMA.

Therefore, the optical bus 104 has a feature that absorption loss is further reduced in addition to the features of the optical bus according to the first embodiment.

[0072]

(Embodiment 1) An optical bus shown in FIG. 6 was prepared according to the following procedure.

The light transmission layer 2 is a rectangular plate-like member having a thickness, width and length of 1 mm, 4 mm and 20 mm, respectively, and is formed of PMMA. The thickness of the light transmission layer 2 is the thickness of the portion where the convex portion 2A is not formed.

In the vicinity of the input side end face 2B and the output side short face 2C in the optical transmission layer 2, that is, on the upper and lower surfaces of the input / output end where signal light enters and exits, a thickness of 0.1 mm and a side of 1 m
The five equilateral triangular protrusions 2A were formed at equal intervals.
However, the convex portions 2A located at both ends have a thickness of 0.1.
mm and the right triangle was formed by cutting the regular triangle having one side of 1 mm in half along the center line. The convex portion 2A
Are formed on the signal light non-arrival portion 2D and the signal light non-coupling portion 2E in the optical transmission layer 2.

The light-shielding layer 4 has the same thickness as the light transmission layer 2,
It is a rectangular plate-like member having a width and a length of 1 mm, 4 mm, and 20 mm, respectively, and is formed of black PMMA mixed with carbon black.

Four light-transmitting layers 2 and five light-shielding layers 4 are formed, and the light-shielding layers 4 and the light-transmitting layers 2 are alternately overlapped and aligned. The optical bus 102 was manufactured by bonding and fixing to the layer 2. (Embodiment 2) As shown in FIG. 2, short cylindrical convex portions 2A having a diameter of 1 mm and a height of 0.1 mm are formed near the respective vertices on the upper and lower surfaces of the light transmission layer 2 as in the first embodiment. did.

Four light-transmitting layers 2 and five light-shielding layers 4 similar to those of the first embodiment were prepared, and the positions of the light-shielding layers 4 and the light-transmitting layers 2 were alternately superimposed and aligned. Then, the light shielding layer 4 was bonded and fixed to the light transmission layer 2 to manufacture the optical bus 100 shown in FIGS. Third Embodiment An input optical fiber 10 and an output optical fiber 20 are connected to the optical bus 102 according to the first embodiment and the optical bus 100 according to the second embodiment, as shown in FIGS.

Each of the input optical fiber 10 and the output optical fiber 20 had a diameter of 1 mm (a core diameter of 0.98 mm).

The input optical fiber 10 and the output optical fiber 20 were connected in parallel, four per optical transmission layer.

The input optical fiber 10 and the output optical fiber 20 were adjusted to the pitch of the optical transmission layer 2 by the positioning blocks 12 and 22, respectively.

The efficiency and distribution when signal light was passed through the optical bus 102 connecting the input optical fiber 10 and the output optical fiber 20 were measured and compared with the efficiency and distribution in the conventional optical bus shown in FIG.

The efficiency was obtained by dividing the intensity of the light emitted from the output optical fiber 20 by the intensity of the light incident from the input optical fiber 10.

The distribution is such that when signal light enters from one of the four input optical fibers 10 connected to each optical transmission layer 2 of the optical bus, the four optical fibers connected to each optical transmission layer 2 From the maximum value and the minimum value of the intensity of the signal light emitted to the output optical fiber 20 according to the following equation.

Distribution = [(maximum value−minimum value) / (maximum value +
(Minimum value)] × 100 The values of the efficiency and the distribution are shown in FIG. FIG. 10 shows the average value of the efficiency. In FIG. 10, “the present invention (circular)” refers to the optical bus 100 shown in FIG. 4 according to the second embodiment, and “the present invention (triangle)” relates to the optical bus 100 shown in FIG. Bus 102 is meant.

As is clear from FIG. 10, the optical bus 102 according to the first embodiment and the optical bus 100 according to the second embodiment
In each case, it can be seen that there is almost no difference in efficiency and distribution from the conventional optical bus.

[0086]

As described above, according to the present invention,
A multi-bit optical bus that is simple to fabricate and that has low loss is provided.

[Brief description of the drawings]

FIG. 1 is a perspective view and a sectional view showing an example of an optical bus according to the present invention.

FIG. 2 is a partially exploded view showing the structure of the optical bus shown in FIG.

FIG. 3 is a plan view showing another example of the optical transmission layer in the optical bus shown in FIG.

FIG. 4 is a perspective view showing a state where an input optical fiber and an output optical fiber are connected to the optical bus shown in FIG. 1;

FIG. 5 is a diagram showing a positional relationship between an optical transmission layer and an optical fiber in the optical bus shown in FIG. 4, how light from the optical fiber is incident on the optical transmission layer, and how the optical transmission layer is formed. FIG. 3 is a schematic diagram illustrating a state in which a propagated signal light is emitted to an output optical fiber.

FIG. 6 is a perspective view showing another example of the optical bus according to the present invention.

FIG. 7 is a plan view showing another example of the optical transmission layer in the optical bus shown in FIG.

FIG. 8 is a perspective view showing a state where an optical fiber is connected to the optical bus shown in FIG. 6;

FIG. 9 is a perspective view showing still another example of the optical bus according to the present invention.

FIG. 10 is a graph showing the transmission efficiency and distribution of signal light for an optical bus according to the present invention and a conventional optical bus.

FIG. 11 is a perspective view and a sectional view showing an example of a conventional optical bus.

[Explanation of symbols]

 Reference Signs List 2 light transmission layer 2A convex part 4 light shielding layer 6 light transmission layer 8 light shielding layer 8A convex part 100 optical bus 102 optical bus 104 optical bus

Claims (5)

[Claims] 1. An optical bus in which signal light is incident from one end and emitted from the other end, wherein: an optical transmission layer for transmitting the signal light from one end to the other end; and two adjacent optical transmission layers A light-shielding layer that prevents signal light from being mixed between the light-transmitting layers, and the light-transmitting layer and the light-shielding layer are alternately stacked,
An optical bus, wherein a gap is formed between the light transmission layer and the light shielding layer. 2. The optical transmission layer and the light shielding layer are both plate-shaped members, and at least one of the light transmission layer and the light shielding layer has a convex portion on a surface, and The optical bus according to claim 1, wherein the optical transmission layer and the light shielding layer are bonded to each other at a portion. 3. The optical bus according to claim 1, wherein the convex portion is a band-shaped protrusion provided on the one end side and the other end side of the optical transmission layer or the light shielding layer. 4. When transmitting an optical signal, an input optical fiber for inputting an optical signal to the optical transmission layer is connected to the one end of the optical transmission layer, and the other end of the optical transmission layer is connected to the input optical fiber. An optical bus to which an output optical fiber for extracting a signal light emitted from an optical transmission layer is connected, wherein the convex portion is a region that is not irradiated by the signal light incident from the input optical fiber on the one end side. 4. A signal light non-coupling portion formed at a signal light non-arrival portion and formed at the other end side at a signal light non-coupling portion within a range in which outgoing light propagated in an optical transmission layer cannot enter an output optical fiber. An optical bus as described in. 5. The optical bus according to claim 4, wherein the convex portion has a triangular prism planar shape whose apex faces a central portion of the optical transmission layer.