JP2002196174A - Optical coupling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical coupling device which is capable of increasing light which can utilize efficiency in an optical data bus. SOLUTION: This optical coupling device is equipped with a substrate 21, having light-emitting elements 52 and light-receiving elements 53, an optical signal transmitting device 10 having a plurality of incidence/emission parts which makes optical signals enter or exit by reflection corresponding to the light-emitting and light-receiving elements, a fixed substrate base 60 with a groove 61, and a light-transmitting plate 62 for holding the fixed substrate. The optical signal transmitting device 10 is arranged at the groove 61 of the fixed substrate base 60 and fastened with screws 63 or the like. Consequently, the incidence/emission parts of the optical signal transmitting device 10 is disposed close to the light-emitting elements 52 or to the light-receiving elements 53.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling device constituting an optical data bus for transmitting an optical signal.

[0002]

2. Description of the Related Art In recent years, with the development of very large scale integrated circuits (VLSI), 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 this circuit function increases, the data bus board (mother board) that connects each circuit board (daughter board) with a bus structure has a large number of connectors and connection lines. The required parallel architecture is adopted. The operation speed of the parallel bus has been improved by promoting parallelization by increasing the number of connection lines and miniaturization. However, the processing speed of the system may be limited by the operation speed of the parallel bus due to the signal delay caused by the capacitance between the connection lines or the connection line resistance. In addition, electromagnetic noise (EMI: Electromagnet) caused by increasing the density of parallel bus connection wirings
ic Interference) is also a major constraint on improving the processing speed of the system. Therefore, optical interconnections, which have been spotlighted mainly in trunk systems, have been applied to the field of electrical wiring between substrates.

[0003] Among various types of conventionally proposed optical interconnection techniques, Japanese Patent Application Laid-Open No. 2-41042 proposes an optical data transmission system using a light emitting / receiving device. In this method, light-emitting / light-receiving devices are arranged on both front and back surfaces of each circuit board, and light-emitting / light-receiving devices on adjacent circuit boards incorporated in the system frame are spatially coupled with each other by light. A serial optical data bus is formed for loop transmission. And
The signal light sent from a certain circuit board is subjected to optical / electrical conversion on an adjacent circuit board, is further subjected to electrical / optical conversion on that circuit board, and is then sent to an adjacent circuit board. As described above, in the present method, the circuit boards are sequentially arranged in series, and the light is transmitted between all the circuit boards incorporated in the system frame while repeating the optical / electric conversion and the electric / optical conversion on each circuit board. Is done. For this reason, the signal transmission speed depends on the light / electric conversion and the electric / light conversion speed of the light receiving / light emitting device arranged on each circuit board, and at the same time is restricted. In addition, since data transmission between the circuit boards uses optical coupling via a free space by light receiving / light emitting devices arranged on each circuit board, interference between adjacent optical data transmission paths ( Crosstalk) occurs and data transmission failure is expected. Also,
It is also anticipated that data transmission failure will occur due to scattering of signal light due to an environment in the system frame, for example, dust or the like.

Japanese Patent Application Laid-Open No. S61-196210 proposes a method of optically coupling circuit boards through an optical path constituted by a diffraction grating and a reflection element arranged on a plate surface. In this method, since light emitted from one point can be connected only to a fixed point, it is not possible to exhaustively connect all circuit boards like an electric bus.

Further, several techniques have been proposed for data transmission between circuit boards using an optical connection device having a branch element. For example, JP-A-58-
Japanese Patent No. 42333 discloses an example of data transmission between circuit boards using a plurality of half mirrors. However, when a plurality of half mirrors are used, the size of the apparatus becomes large, and optical alignment with a light emitting / receiving device is required for each mirror. Also, the transmitted light that has passed through the half mirror has a light intensity that is almost half of the incident light.Therefore, if the light is repeatedly branched and transmitted a plurality of times, the light intensity becomes weak, and the light receiving device cannot obtain sufficient light intensity. However, there is a problem that signal transmission becomes impossible.

Japanese Patent Application Laid-Open No. 4-134415 proposes a system in which signal light is incident from a side surface of a lens array having a plurality of lenses and emitted from each lens. In this method, the closer the lens is to the light incident position, the larger the amount of emitted light becomes. Therefore, there is a concern that the intensity of the output signal varies depending on the positional relationship between the incident position and the output position. In addition, since the ratio of light incident from the side surface passing through the opposite side surface is high, the utilization efficiency of the amount of incident light is low.

Further, an optical bus system using an optical fiber capable of transmitting a substantially uniform optical signal by sequentially increasing the branching ratio from the input end is disclosed in Japanese Patent Laid-Open No. 63-122.
No. 3 discloses this. A method of forming a coupler that can be adapted to such a method is disclosed in IEEE Photonics.
Technology Letters, vol.
8, No. 12, December (1996). The method of forming the coupler shown here is
Branching is performed by a V-groove formed in the optical fiber. It is considered that the output light quantity can be adjusted by adjusting the size of the V-groove, but its production is very difficult and the utilization efficiency of the incident light quantity is low.

[0008] A star coupler for equalizing the intensity of the branched signal light is disclosed in Japanese Patent Application Laid-Open No. 9-184941. This star coupler is, generally, bundled and fixed at one end of a plurality of optical fibers, abuts a light guide path having a width covering the plurality of optical fibers on one end face thereof, and a light diffuse reflection means on the other end face. It has. When data transmission between circuit boards is performed using such a coupler, the problem is that if the number of connection boards increases, the number of fibers connected to the light emitting and receiving elements increases, the configuration becomes complicated, and the device becomes large. Occurs.

In connection with these problems, “Electronics”, October 2000, pp. 49-53, “New Concept Optical Sheet Bus Technology” proposes an optical data bus using a flat light guide. I have. This optical data bus has a plurality of step-shaped steps on one end surface of a rectangular parallelepiped flat plate light guide path, and each of these steps forms an input / output section for an optical signal facing a light emitting element or a light receiving element. And
A reflection / diffusion optical system is disposed on the other end face of the light guide path. In such a configuration, the optical signal incident from the input / output unit travels through the flat optical waveguide to the reflection / diffusion optical system, is reflected there, returns to each of the above-mentioned input / output units, and is output therefrom. In this optical data bus, the intensity of the signal light emitted from the flat optical waveguide is substantially uniform, and a good bus system can be obtained.

[0010]

However, in this type of light guide path, the signal light emitted from each input / output section and received by the corresponding light receiving element is considerably reduced as compared with the original signal light. There was a problem that light use efficiency was poor.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical coupling device capable of improving the light use efficiency in an optical data bus.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies on the cause of the decrease in the signal light received by the light receiving element, and as a result, have found that there is a problem specific to this type of light guide path. This has led to the present invention. That is, in this type of light guide path, the outgoing light emitted from the input / output unit is such that the optical signal reflected or diffused in the light guide path is reflected on the oblique surface of the input / output unit and output. It has a certain spread angle. For this reason, if the distance between each input / output section and the corresponding light receiving element increases, the amount of signal light received by each light receiving element decreases. The present invention
This was done with a focus on this point.

An object of the present invention is to provide a light signal transmission device having a substrate having a light emitting element and a light receiving element, a plurality of input / output sections for inputting / outputting an optical signal by reflection corresponding to the light emitting element and the light receiving element, By an optical coupling device including an optical signal transmission device and an attachment member that disposes the substrate in close proximity,
Achieved. Here, the mounting member may include a light-transmitting plate between the optical signal transmission device and the substrate. In addition, the light-transmitting plate member may include a hole through which the light emitting element and the light receiving element penetrate. Further, the mounting member may include a plate member provided with a hole penetrating the light emitting element and the light receiving element between the optical signal transmission device and the substrate. Further, the attachment member may be a spacer provided between the optical signal transmission device and the substrate. Note that the close arrangement includes close contact between the optical signal transmission device and the light emitting element or the light receiving element.

Further, the optical coupling device according to the present invention has a substrate having a light emitting element and a light receiving element, and a plurality of input / output sections corresponding to the light emitting element and the light receiving element for inputting or outputting an optical signal by reflection. Further, the input / output section includes a light-transmitting medium disposed close to the light emitting element or the light receiving element. Here, the incident / exit portion may be provided in a step-shaped step portion formed at one end of the translucent medium.
In this case, the other end of the translucent medium may include a reflection unit that reflects an optical signal and a reflection / diffusion unit that reflects and diffuses an optical signal. Further, the input / output section may be provided at both ends of the translucent medium. In this case, one end of the translucent medium may be provided with a reflection / diffusion means for reflecting / diffusing an optical signal. Note that the close arrangement includes close contact between the input / output unit and the light emitting element or the light receiving element. With this configuration, it is possible to favorably prevent the signal light to be received by the light receiving element from decreasing, and to improve the light use efficiency.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic configuration diagram showing an embodiment of an optical coupling device according to the present invention, and FIG. 1B is a partially enlarged view thereof. As shown in the drawing, a plurality of circuit boards 50 are arranged on one surface of a support substrate 20 such as a printed wiring board via a board connector 40, and a plurality of light emitting elements 52 are arranged on the other surface. , A light receiving element 53 and an electronic circuit 54 are arranged. Although not shown, a power supply line and electric wiring for electric signal transmission are arranged on the support substrate 20. Further, a plurality of optical signal transmission devices 10 for transmitting optical signals are fixed to the support substrate 20. The optical signal transmission device 10 has one side formed in a stepped shape, and each end of the stepped shape can be optically coupled to a light emitting element 52 or a light receiving element 53, respectively, as shown in FIG. Are located in Here, the circuit board 50 includes an LSI such as a CPU, a device such as a memory card and a hard disk drive, in addition to a ceramic substrate and a glass epoxy substrate.

In the optical coupling device configured as described above, the electric signal output from each circuit board 50 is transmitted to the light emitting element 52 via the board connector 40, and the optical signal output from the light emitting element 52 is output. Is received by the light receiving element 53 via the optical signal transmission device 10 and converted into an electric signal, and then transmitted to each circuit board 50 via the board connector 40. Here, since the optical signal transmission device 10 is optically coupled to each of the light emitting elements 52 and the light receiving elements 53, the optical signal emitted from the light emitting element 52 is provided at the stepped end of the optical signal transmission device 10. It is incident on one, passes through the optical signal transmission device 10, exits from the other end, and is received by the light receiving element 53. With this configuration, transmission / reception of a parallel optical signal composed of a plurality of bits or independent simultaneous transmission / reception of each bit can be performed.

FIG. 2A is a diagram showing an example of the optical signal transmission device 10. As shown, the optical signal transmission device 10 includes:
The light-transmissive medium 1 has a stepped step portion 12 formed at one end of a rectangular parallelepiped. The light-transmissive medium 1 has the other end provided with a reflective layer 2. The step portion 12 has an incident / exit portion 13 having a shape cut at an angle of 45 °. This input / output unit 1
3, the optical signal enters and exits in the direction of the upper surface of the translucent medium 1 (on the support substrate 20 side in FIG. 1).

FIG. 2B is a diagram for explaining an example of a propagation (branch) path of an optical signal. In this example, the optical signal enters from the input / output unit 131, and the input / output units 131, 132,
It exits from 133 and 134. That is, the input / output unit 13
The optical signal incident from 1 is reflected at its 45 ° end face, travels straight through the translucent medium 1, reaches the reflective layer 2 and is reflected. The reflected optical signal propagates through the translucent medium 1 again, is guided to the input / output sections 131, 132, 133, and 134, is reflected at the 45 ° end faces thereof, and is output toward the upper surface. You. In this example, the four input / output sections 13
Although the translucent medium 1 having (131, 132, 133, 134) has been described, the number of the incident / exit portions 13 is not limited to this, and can be formed more or less.

Further, a cladding layer (not shown) having a smaller refractive index than that of the translucent medium 1 can be disposed on the upper and lower surfaces or the left and right side surfaces of the translucent medium 1. Thereby, the translucent medium 1 surrounded by the cladding layer functions as a core part forming a light guide path. As the translucent medium 1, a plastic material such as polymethyl methacrylate, polycarbonate, amorphous polyolefin, or inorganic glass can be used. The step-shaped step portion can be processed by grinding, but in the case of a plastic material, it can also be manufactured by a method such as injection molding.

As the reflection layer 2, a metal mirror surface of Al or the like can be used. Further, a reflective diffusion layer can be used for the reflective layer 2 as described later. The reflection type diffusion layer is formed by, for example, a beam shaping diffuser: LSD (Phys
Ical Optics Corporation)
By using, the spread angle of the diffused light in the thickness direction and the spread angle in the width direction can be controlled with respect to the translucent medium 1, and the uniformity of the emitted light intensity can be improved.

FIGS. 3A and 3B show a specific example of the optical signal transmission device 10 used in the present invention. FIG. 3A is a plan view, and FIG.
Is a side view. As shown in the figure, the translucent medium 1 has a stepped step portion 12 on one side of a rectangular parallelepiped shape. On the other end face of the translucent medium 1, a reflective diffusion layer 3 is disposed. Each of the steps 12 has an input / output section 13A.
To 13H, and each input / output section has 4
An oblique surface having an angle of 5 ° is formed. As shown,
The light emitting element 52 is optically coupled to the incident / exit sections 13A, 13C, 13E, and 13G, and the light receiving element 53 is optically coupled to the incident / exit sections 13B, 13D, 13F, and 13H.

As a material of the translucent medium 1, for example, polymethyl methacrylate (refractive index: 1.49) is used, and as the reflective diffusion layer 3, the diffused light intensity distribution is Gaussian distribution, and the diffusion angle (full width at half maximum) ) Is 40 °. The translucent medium 1 has, for example, a total length of 1.
It is 50 mm in width, 8 mm in width, and 1 mm in thickness, and is the closest input / output section 13A from the end face on which the reflective diffusion layer 3 is disposed.
The distance 11 is 80 mm, the length of the step-like step 12 is 10 mm, and the width of the step-like step 12 is 1 mm.

In this example, for example, the optical signal emitted from the light emitting element 52 to the input / output unit 13A is
The optical path is bent 90 ° by the 45 ° oblique surface formed in A, propagates through the translucent medium 1 and enters the reflection type diffusion layer 3, where it is reflected and diffused by the reflection / diffusion action, and goes to each of the input / output sections. Is propagated. The diffused light that arrives at each input / output section is 4
The optical path is bent 90 ° by the 5 ° oblique surface, and the light transmitting medium 1
And is received by the light receiving element 53.

Here, as the light emitting element 52, for example, a surface emitting laser having a divergence angle of 10 ° is used, and as the light receiving element 53, a PIN photodiode having a light receiving area of φ0.8 mm is used. It is a can package. This packaged light emitting element 5
2. The light receiving element 53 is mounted on a printed wiring board (support substrate). Here, the form of the package is not limited to the can package, and ceramic, plastic, or the like may be used.

FIGS. 4A to 4C are views showing an embodiment of the optical coupling device according to the present invention. As shown in FIG. 1A, the optical signal transmission device 10 is inserted into a groove 61 formed in the fixed substrate base 60. The groove 61 is formed to have a thickness approximately equal to or slightly smaller than the thickness of the optical signal transmission device 10. The optical signal transmission device 10 inserted into the groove portion 61 is fixed to the fixed substrate base 60 with screws 63 or the like using a fixed substrate pressing plate 62 having a thickness of about 1 mm formed of a translucent plastic material. .

On the other hand, as shown in FIG. 4B, a light emitting element 52 and a light receiving element 53 are arranged on the printed wiring board (support substrate) 21. This printed wiring board 2
1, the fixed substrate base 60 in which the above-described optical signal transmission device 10 is inserted is overlapped and fixed. That is, the fixed substrate base 6 is arranged such that the input / output sections 13A to 13H of the optical signal transmission device 10 are optically coupled to the light emitting element 52 or the light receiving element 53.
4 is superimposed on the printed wiring board 21 in a form as shown in FIG. 4C, and both are fixed using screws 63 or the like.

As a result, the distance between the input / output sections 13A to 13H and each light emitting element or each light receiving element is uniformly reduced. With such a configuration, since each light receiving element is arranged close to the incident / emission section, even if the emitted light is emitted from the incident / emission section at a certain divergence angle, the signal light received by each light receiving element is reduced. And light use efficiency can be improved.

FIGS. 5A to 5C are views showing another embodiment of the optical coupling device according to the present invention. In the present embodiment, as shown in FIG.
4 and a point that a hole 64 through which the light receiving element 53 can pass is provided. By providing such a hole portion 64, it is possible to further arrange the incident / exit portions 13A to 13H closer to each light receiving element or light emitting element. According to this embodiment, since each light receiving element is arranged close to the incident / exit portion, the light use efficiency can be improved.

Here, the fixed substrate base 60 corresponds to FIG.
As shown in (a), the optical signal transmission device 10 for each bit
May be inserted, or FIG.
(B) As shown in FIG.
May be inserted.

FIGS. 7A and 7B show another embodiment of the optical coupling device according to the present invention. In the present embodiment, FIG.
The configuration and schematic dimensions of the optical signal transmission device 10, the light emitting element 52, the light receiving element 53, etc.
This is the same as the previous embodiment. In the present embodiment, first, the fixed substrate base 60 is fixed on the printed wiring board 21 on which the light emitting element 52 and the light receiving element 53 are arranged by screws 63 or the like. The fixed signal base 1 is provided on the fixed substrate base 60.
A groove 61 'is formed so as to insert a zero. By arranging the optical signal transmission device 10 in the groove 61 ', the input / output portion of the optical signal transmission device 10, the light emitting element 52, and the light receiving element 53 are arranged close to each other, and efficient optical coupling is possible. The optical signal transmission device 10 is fixed to a fixed substrate base 60 by a fixed substrate pressing plate 62 using screws 63 and the like. According to the present embodiment, since each light receiving element is arranged close to the incident / exit portion, it is possible to improve light use efficiency.

FIGS. 8A and 8B are views showing another embodiment of the optical coupling device according to the present invention. In the present embodiment, as shown in FIG.
7 and a hole 64 'through which the light receiving element 53 can pass is different from the embodiment of FIG. By providing such a hole 64 ′, it is possible to further arrange the incident / exit portions 13 </ b> A to 13 </ b> H to each light receiving element or light emitting element. According to this embodiment, since each light receiving element is arranged close to the incident / exit portion, the light use efficiency can be improved.

FIGS. 9A and 9B are views showing another embodiment of the optical coupling device according to the present invention. In the present embodiment, as shown in FIG. 1A, the optical signal transmission device 10 is fixed to a support substrate 20 on which a plurality of circuit boards 51 are arranged. Then, as shown in FIG. 4B, both the light emitting element 52 and the light receiving element 53 are arranged so as to be optically coupled to each of the input / output sections of the optical signal transmission device 10. In the previous embodiment, since the light emitting element 52 or the light receiving element 53 is arranged at the input / output part of the optical signal transmission device 10, this embodiment is different in this point. In this embodiment, for example, an element (not shown) in which both a surface emitting laser and a PIN photodiode are mounted in one package can be used. According to this embodiment, since each light receiving element is arranged close to the incident / exit portion, it is possible to improve the light use efficiency.

FIGS. 10A and 10B show still another embodiment of the optical coupling device according to the present invention, wherein FIG. 10A is a perspective view, FIG. 10B is a side view, and FIG. 10C is a plan view. In the present embodiment, as shown, the support substrate 20, a plurality of light emitting elements 52 disposed at one end thereof, and a plurality of light receiving elements 53 disposed at the other end thereof.
An optical signal transmission device 10 'having a translucent medium 1' having a 45 ° oblique surface formed at both ends so as to enable optical coupling with the light emitting element 52 and the light receiving element 53; And a spacer 70 for arranging 10 ′ close to the light emitting element 52 and the light receiving element 53. Here, the reflective diffusion layer 3 is disposed on the oblique surface of the translucent medium 1 'on the light emitting element 52 side.

In this embodiment, an optical signal emitted from one light emitting element 52 is incident on a translucent medium 1 'and then reflected and diffused by a reflective diffusion layer 3, and the reflected diffused light is transmitted to the translucent medium. 1 ', the light proceeds to the light receiving element 53 side, and the light is reflected again by the other oblique surface.
Is received at. According to this embodiment, since each light receiving element is arranged close to the incident / exit portion, it is possible to improve the light use efficiency.

Although various embodiments have been described above, the present invention is not limited to these embodiments. For example, the configuration of the light-transmitting medium can take another form than that described above. As described above, according to the present invention, it is possible to provide an optical coupling device having high light use efficiency, which includes an optical signal transmission device, a light receiving element, a light emitting element, and the like. In addition, if a signal processing device or an optical data bus having a plurality of circuit boards is configured by using the optical coupling device, a signal can be transmitted between any circuit boards, and a change in environment such as a temperature change and dust can be prevented. An optical bus system with high resistance can be obtained.

[0036]

According to the present invention, it is possible to obtain an optical coupling device capable of improving light use efficiency in an optical data bus.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram showing an embodiment of an optical coupling device according to the present invention, and FIG. 1B is a partially enlarged view thereof.

FIG. 2A illustrates an example of an optical signal transmission device 10;
FIG. 4B is a diagram for explaining an example of a propagation (branch) path of an optical signal.

3A and 3B are diagrams showing a specific example of an optical coupling device used in the present invention, wherein FIG. 3A is a plan view and FIG. 3B is a side view.

FIGS. 4A to 4C are diagrams illustrating an embodiment of the optical coupling device according to the present invention.

FIGS. 5A to 5C are diagrams showing another embodiment of the optical coupling device according to the present invention.

FIGS. 6 (a) and (b) are diagrams each showing a configuration example of a fixed substrate base.

FIGS. 7A and 7B are diagrams showing another embodiment of the optical coupling device according to the present invention.

FIGS. 8A and 8B are views showing another embodiment of the optical coupling device according to the present invention.

FIGS. 9A and 9B are diagrams showing another embodiment of the optical coupling device according to the present invention.

FIGS. 10A and 10B are diagrams showing still another embodiment of the optical coupling device according to the present invention, wherein FIG. 10A is a perspective view, FIG.
(C) is a plan view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Translucent medium 2 Reflective layer 3 Reflective diffusion layer 10 Optical signal transmission device 13, 131-134, 13A-13H Input / output part 20 Support board 21 Printed wiring board 40 Connector 50, 51 Circuit board 52 Light emitting element 53 Light receiving element 54 Electronic circuit 60 Fixed substrate base 61, 61 'Groove 62 Fixed substrate pressing plate 63 Screw 64, 64' Hole

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hidenori Yamada 430, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Green Tech Inside Fuji Xerox Co., Ltd. F-term (reference) 2H037 AA01 BA02 BA11 CA39 DA03 5F073 AB15 AB16 BA01 FA05 FA30

Claims (11)

[Claims] A substrate having a light emitting element and a light receiving element;
An optical signal transmission device having a plurality of input / output sections for inputting or outputting an optical signal by reflection corresponding to the light emitting element and the light receiving element; and a mounting member for disposing the optical signal transmission apparatus and the substrate in close proximity to each other. An optical coupling device. 2. The optical coupling device according to claim 1, wherein the mounting member has a light transmitting plate between the optical signal transmission device and the substrate. 3. The optical coupling device according to claim 2, wherein the translucent plate member has a hole through which the light emitting element and the light receiving element penetrate. 4. The light according to claim 1, wherein the mounting member has a plate member provided with a hole through which the light emitting element and the light receiving element pass between the optical signal transmission device and the substrate. Coupling device. 5. The optical coupling device according to claim 1, wherein the mounting member is a spacer provided between the optical signal transmission device and the substrate. 6. A substrate having a light emitting element and a light receiving element,
A light-transmitting medium having a plurality of input / output sections for inputting / outputting an optical signal by reflection corresponding to the light-emitting element and the light-receiving element, wherein the input / output section is disposed in proximity to the light-emitting element or the light-receiving element; An optical coupling device. 7. The optical coupling device according to claim 6, wherein the input / output section is provided at a step-shaped step formed at one end of the light transmitting medium. 8. The optical coupling device according to claim 7, further comprising a reflection means for reflecting an optical signal at the other end of said translucent medium. 9. The light-transmitting medium according to claim 7, further comprising a reflection-diffusion means for reflecting and diffusing an optical signal at the other end of the light-transmitting medium.
The optical coupling device according to claim 1. 10. The optical coupling device according to claim 6, wherein the input / output sections are provided at both ends of the translucent medium. 11. An optical coupling device according to claim 10, further comprising a reflection / diffusion means for reflecting / diffusing an optical signal at one end of said translucent medium.