JPH095581A - Optical interconnection device between boards - Google Patents

Abstract

(57) [Abstract] [Purpose] Providing an inter-board optical interconnection device that enables ultra-high-speed, ultra-high-density, and ultra-high-capacity inter-board optical connections while achieving economic efficiency by eliminating the need for electrical connectors and mechanical alignment. To do. [Structure] Boards 1-1 arranged in a bookshelf shape
In addition to the electric components, a surface-emission laser array 1-3 and a surface detector array 1-4 are mounted on -a to 1-1-e, and an emission light beam 1-from the surface-emission laser array 1-3 is mounted.
Reference numeral 5 is coupled to the surface detector array 1-4 in a contactless manner without using a connector via the optical connection circuit 1-2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a board-to-board optical interface for connecting a board mounted with electrical components in a bookshelf form to connect signals of ultra-high speed, ultra-high density, and ultra-large capacity using light. Regarding connection device.

[0002]

2. Description of the Related Art In this type of conventional inter-board optical interconnection device, the inter-board connection currently put into practical use is based on electrical signals, and its performance depends on the pin density of electrical connectors and the speed of signals that can be transmitted. Is determined by.
The current connector pin density is about 1 pin / mm ² . At present, to send an electric signal of several cm at a speed of 100 Mbps, 1
About W is necessary, and it is necessary to consider heat dissipation.

When high-speed signals pass between boards, EM
The problem is that C noise is generated. For this reason, it is said that several 100 Mbps and a connector density of 1 wire / mm ² are the limits when connecting the boards with an electric signal. However, signal speed and connector density tend to increase year by year, approaching this limit. In order to overcome this limitation, light-to-board interconnections have attracted attention.

An optical interconnection for connecting a multi-channel laser array and a detector array with a fiber array is currently under development, and will be commercially available at low cost in the near future. LED or LD is used as a light source, and 150
It is planned to be marketed at a few thousand yen per channel at Mbps. However, such an optical interconnection module has a maximum of about 10 ch and has a throughput of 1
The limit is about 0 Gbps. Larger capacity optical interconnection is desired.

British Telecom's P. Healey et al.
We proposed a board-to-board bus connection using D-fiber (P. Healey, "Chapter 7 Multidimensional Switching S").
ystems in Photonics in Switching, Vol.II, "Edited by
JEMidwinter, Pressed by Academic Press (London)
reference).

FIG. 9 shows the proposal. 9-1 is a board,
9-2 is an electric component such as an LSI, 9-3 is an E / O element for converting an electric signal from the electric component into an optical signal, and 9-4
Is a D-fiber for connecting this optical output to the backplane, and 9-5 is a D-fiber laid in the backplane. The D-fiber is a fiber obtained by cutting off a part of the cladding and core of an ordinary optical fiber as shown in the lower side of the figure. By touching this part of the two D-fibers, the light couples. Bus connection is realized using this principle. However, there is a disadvantage that an optical amplifier must be inserted between the boards because the loss of the optical fiber in the scraped off portion is large.

Also, Hinton et al. Proposed an optical bus connection that uses a two-dimensional optical switch (smart pixel) having an optical detector array, a logic circuit and an optical modulator array mounted on a board, and performs optical connection in free space between them. (T.Sz
ymanski and HSHinton, Architecture of a Terabit F
ree-space photonic backplane, The international con
ferece on optical computing technical digest, OC'9
4, Edinburgh, Scotland, August 22-25, 1944) WD2 / 221
reference).

A representative of the two-dimensional optical switch is SEE from Bell Lab.
It is a D element. FIG. 10 is a diagram showing the structure of a backplane using the same. 10-1 is a board, 10-2 is electrical components to be mounted, 10-3 is a smart pixel array, 10-4 is a light beam array between smart pixels,
10-5 is a backplane and 10-6 is an electrical connector for connecting the backplane and the board. A light beam connects the surface emitting laser, the detector and the smart pixel array consisting of logic circuits. The optical signal is transmitted while digitally reproducing between the adjacent smart pixels. However, this method requires a two-dimensional smart pixel device that receives light on the back surface and emits light on the front surface, but such a device has not been realized at present. Furthermore, there is a drawback that the signal speed and density are limited by the high-speed electrical connector that connects the optical backplane and the board. In addition, such a backboard has a drawback of high cost.

Further, there has been proposed an inter-board optical bus using an optical fiber and a coupler as shown in FIG. 11
-1 is a board on which electrical components such as LSI are mounted, 11
-2 is a multi-pin connector for connecting the electrical output from the board to the backboard, 11-3 is an electrical / optical conversion circuit for converting this electrical signal to light, and an optical signal from the optical bus connection to an electrical signal Optical / electrical conversion circuit for converting, 11-4
Is an optical fiber, and 11-5 is an optical coupler. The optical signals from all the boards are converted to light by the optical couplers, distributed to all the boards by the couplers, and converted to electricity again. In the above method, since the optical bus is connected by the optical fiber, complicated alignment is not necessary. However, one coupler is required for one electric signal, and since a higher-speed electric signal is passed through the connector 11-2, there is a problem that the connector pin density cannot be increased and a problem of EMC.

It has also been proposed to use a hologram to connect the boards with a light beam in free space and to bend the light. FIG. 12 is a diagram showing this configuration.
1 is a board, 12-2 is an electric component such as an LSI, 12-
An E / O element 3 converts an electric signal from the board into an optical signal, and here, a semiconductor laser with a collimating lens is used. Reference numeral 12-5 is a hologram element that bends the light beam emitted from the semiconductor laser to a desired point, and 12-6 is a backboard that supports the board.
2-7 is an element for receiving this light beam, and 12-8
Is a light beam. In the above method, the optical connection between the two sheets is possible, but the bus connection is not possible, and it is impossible to connect the thin beam because the alignment mechanism for connecting the optical beam is not provided. It is believed that there is.

[0011]

As described above, in the conventional method, there is a problem that the loss of the fiber in the scraped-off portion is large and an optical amplifier must be inserted between the boards, or the electrical connector is used. There are problems that the signal speed and density are limited and the cost of the backboard is high, and that one coupler is required for each electric signal, and the connector pin density cannot be improved. Further, there is a problem that the bus connection is impossible and it is impossible to connect a thin beam, so that an ultra-high speed, ultra-high density, and ultra-large capacity optical connection has not been realized.

The present invention has been made in view of the above,
The aim is to provide an inter-board optical interconnection device that enables ultra-high-speed, ultra-high-density, and ultra-high-capacity inter-board optical connections while achieving economic efficiency by eliminating the need for electrical connectors and mechanical alignment. It is in.

[0013]

In order to achieve the above object, the present invention as set forth in claim 1, is a board-to-board optical system for mounting a board on which an electric circuit is mounted in a bookshelf form and exchanging signals between the boards. An interconnection device, in which a surface emitting laser array that emits an optical signal and a surface detector array that receives the optical signal are mounted on the board in addition to an electric circuit, and an optical connection circuit including an optical fiber group between the arrays. Is equipped with a mechanism for allowing a light beam received at an arbitrary location to enter an optical fiber and emit to an arbitrary location.The surface emitting laser array, the optical fiber optical connection circuit, and the surface detector array are in contact with each other. The point is that they are connected by a light beam in a free space without performing any operation.

The present invention according to claim 2 is the same as claim 1.
In the invention described above, in order to accurately couple the light beam emitted from the board to the optical fiber of the optical connection circuit, and to accurately couple the light beam emitted from the optical fiber of the optical connection circuit to the photodetector. Therefore, a guide hole for position determination is formed on the board or the optical connection circuit, a movable guide pin is provided on the board or the optical connection circuit, and when the board is inserted,
The guide pin is pushed out and inserted into the guide hole to establish a positional relationship with each other, and then the optical fiber group approaches the surface emitting laser array, the surface detector array along the guide pin, and the optical fiber array and The gist of the present invention is to provide a mechanism for keeping the distance between the surface detector array and the optical fiber array 5 mm or less.

Further, the present invention described in claim 3 provides the invention according to claim 1.
Alternatively, in the invention described in 2, the optical wiring board disposed between the boards has a hole at a position corresponding to a light beam emitted from the board, and a light having ferrules at both ends for inserting into the hole. The gist is that the combination of optical fibers is determined by the combination of inserting the optical fiber into the hole.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, a lens or a lens array is provided at the tip of the surface emitting laser array, the surface detector array, or the optical fiber array. What is done is the summary.

Further, the present invention described in claim 5 is based on claim 1.
In the invention described in any one of (1) to (4), the gist is that the optical fiber is a step index multimode optical fiber having a core diameter of 50 microns or more.

Further, the present invention according to claim 6 provides the invention according to claim 5.
In the invention described above, the gist is that the optical fiber is a plastic optical fiber.

A seventh aspect of the present invention is characterized in that, in the fifth or sixth aspect of the invention, the multimode optical fiber is a multi-core image optical fiber.

[0020]

According to the present invention of claim 1, an optical connection circuit composed of an optical fiber group is arranged between the surface emitting laser array and the surface detector array mounted on the board, and the optical connecting circuit is received at an arbitrary position. The light beam enters the optical fiber and is emitted to an arbitrary place, and the surface emitting laser array, the optical fiber optical connection circuit, and the surface detector array are connected by the light beam in the free space without contacting each other.

According to the present invention of claim 2,
When the board is inserted, the guide pins are pushed out and inserted into the guide holes on the board or the optical connection circuit to establish the positional relationship with each other, and the outgoing light beam from the board is accurately applied to the optical fiber of the optical connection circuit. Coupling and accurately couple the light beam from the optical fiber of the connection circuit to the photodetector, and the optical fiber group approaches the surface emitting laser array and the surface detector array along the guide pin, The distance between the detector array and the optical fiber array becomes 5 mm or less.

Further, in the present invention according to claim 3,
The optical wiring board between the boards consists of a board with holes formed at the positions corresponding to the light beams from the boards, and optical fibers with ferrules at both ends for inserting into the holes. It is determined by the combination to be inserted into.

In the present invention according to claim 4, a lens or a lens array is arranged at the tip of the surface emitting laser array, the surface detector array, or the optical fiber array.

According to the present invention of claim 5,
The optical fiber is a step index multimode optical fiber having a core diameter of 50 microns or more.

Further, in the present invention according to claim 6,
The optical fiber is a plastic optical fiber.

According to the present invention of claim 7, the multimode optical fiber is a multi-core image optical fiber.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the basic concept of an inter-board optical interconnection device according to an embodiment of the present invention. In the figure, reference numerals 1-1-a to 1-1-e are board rows arranged in a bookshelf shape, and LSIs are arranged thereon.
Electrical components such as. Reference numeral 1-2 is an optical connection circuit in which an optical fiber is wired, 1-3 is a surface emitting laser array mounted on a board, and 1-4 is a surface detector array mounted on the board. Reference numeral 1-5 indicates the light beam emitted from the surface emitting laser and the light beam emitted from the optical fiber. The optical interconnection between the boards uses a surface emitting laser and a surface detector on the board, and they are connected by an optical fiber. These are connected by a light beam in free space.

Unlike the prior art, conventionally, the optical fiber was taken out from the end of the board and optically connected in the lower backplane, but in this embodiment, the entire space between the boards is used. Therefore, a large-capacity optical wiring can be realized. Although only the cross wiring is shown in the figure for simplification, more complicated optical wiring is also possible. Further, as shown in the enlarged view of the lower side of FIG. 1, a connector is not used between the optical fiber, the surface emitting laser, and the photodetector, and they are mutually coupled by a light beam without contact. This non-contact avoids the problem of damage to the fiber, laser array, and detector array due to mechanical contact during board insertion and removal. Further, by providing the guide pins 1-6, the fiber array and the surface emitting laser array,
A surface detector can be connected.

FIG. 2 is a detailed view of FIG. 1 viewed from the front, and 2-1 is a group of light beams emitted from the surface emitting laser, 2
-2 indicates a fiber group, 2-3 indicates a ferrule group, and 2-
4 is a holding plate for holding the fiber group ferrule,
Reference numeral 2-5 indicates a movable guide pin for aligning the optical fiber group with the surface emitting laser array and the photodetector array. Reference numeral 2-6 indicates a guide hole into which the guide pin is inserted.

FIG. 3 shows the structure of the optical connection circuit in detail. 3
Reference numeral -1 is a holding plate for fixing the optical fiber, and this is provided with a hole 3-2 for inserting the fiber. 3
-3 is a ferrule for an optical fiber. Reference numeral 2-2 is an optical fiber group. Here, since light propagates only at a distance of about several tens of cm at most, a step index type plastic optical fiber having a large core diameter is used. When the core is 50 μm or more, the coupling becomes very easy. The plastic optical fiber is inexpensive and has a characteristic of being resistant to bending. It is most suitable for bending and wiring a large number of optical fibers in a narrow space between boards as in this embodiment. Alternatively, a silica glass fiber may be used, and a core having a step index core as thick as 100 μm can also be used. Further, since the board is air-cooled, the holding plate 3-1 has an uneven structure so that air flows from the bottom to the top as shown in 3-4. Reference numeral 3-5 is a guide pin, and after the board is inserted, this guide pin is inserted into the guide hole on the board to establish the positional relationship with each other. Here, for the sake of explanation, the width is drawn wide, but since this optical connection circuit is actually inserted between the boards, this width is narrow, 5 cm or less.

FIG. 4 is an enlarged view of a portion around the surface emitting laser array and the photodetector array installed on the back surface of the board. 4-1 is a light beam array emitted from the surface emitting laser, 4-2 is a microlens array, 4-3 is a surface emitting laser array chip, 4-4 is a socket pin, 4-
Reference numeral 5 is an IC socket. 4-6 is a board, 4-7 is a detector socket, 4-8 is a socket pin, 4-9
Is a photodetector array chip, 4-10 is a microlens array, and 4-11 is a light beam array emitted from an optical fiber. Here, the light emitting surface and the light receiving surface are arranged on both sides of the board. But mirror,
Alternatively, the exit surface and the light receiving surface may be installed on the same surface of the board by using a prism.

FIG. 5 is a drawing for explaining step by step how a board is inserted and coupled with an optical fiber. 5-
Reference numeral 1 is a connector for inserting a board and supplying an electric signal, and also has a function of fixing the board at the same time.

In FIG. 5A, the board 1-1-a is inserted from the upper side. At this time, the optical guide pin and the fiber are in a retracted state, and the board can be freely inserted. (2) shows a state in which the board is inserted into the electrical connector 5-1.
(3) shows a state where the guide pins 5-2 on the fiber fixing and holding plate are inserted into the guide holes 2-6 on the board and their positions are fixed. (4) shows a state in which the fiber fixing and holding plate approaches the photodetector array along the guide pin, the distance between them is 5 mm or less, and the light beam emitted from the optical fiber group is coupled to the photodetector array. Shows. As described above, the surface-emitting laser array, the photodetector array, and the optical fiber array on the board are accurately aligned by the four steps of inserting the board, fixing the board, inserting the guide pin, and bringing the fiber array into proximity. To be ringed.

FIG. 6 shows an optical fiber used in an optical wiring board. FIG. 1A shows one optical fiber, 6-1 is a ferrule, 6-2 is an optical fiber core wire,
6-3 is a coating. The optical fiber used here is a multimode optical fiber and preferably has a large core diameter. Therefore, it is desirable that the core diameter is several 50 μm or more.

FIG. 6 (b) shows a multi-core fiber. Reference numeral 6-4 is a multi-core fiber having 9 cores. When this optical fiber is used, the surface emitting laser array and the photodetector array also have the same light emitting pattern and light receiving pattern. 6-5 is a fiber having a multi-core number of several hundreds or more, and this fiber is usually called an image optical fiber. When this fiber is used, there is an advantage that light is coupled even if the positional accuracy of the surface emitting laser array and the photodetector array is poor. Figure 6
(C) shows an optical fiber array. By inserting the optical fiber core wire 6-2 into the ferrule 6-1 and housing the ferrule in the fixed frame 6-6, an accuracy of ± several μm can be obtained. The fibers (a) to (c) described above can be used for an optical wiring board for inter-board optical interconnection.

FIG. 7 shows how the optical fiber is coupled to the surface emitting laser array and the photodetector array. 7-1 is a surface emitting laser array, 7-2 is a light beam array emitted from the surface emitting laser, 7-3 is an optical fiber array, 7-4 is a light beam array emitted from an optical fiber, 7-5. Is a photodetector array, 7-6 is a microlens array, 7-7 is a single lens, and 7-8 is an image fiber or a multicore fiber.

In FIG. 7A, the light beam emitted from the surface emitting laser is coupled to the core of the optical fiber without passing through the lens. Since the divergence angle of the light beam emitted from the surface emitting laser is as small as about 10 degrees, it is possible to couple the light beam to the optical fiber relatively easily without using a lens.

FIG. 7B shows a structure in which a surface emitting laser for emitting light and a microlens array 7-6 installed on the optical fiber side. The light emitted from the surface emitting laser array becomes a light beam by the microlens and is coupled to the optical fiber array and the photodetector.

FIG. 7C shows a structure in which microlens arrays 7-6 are provided on both the light emitting side and the light receiving side.

FIG. 7D shows the case where an image fiber or a multi-core fiber array 7-8 is used. Here, a single lens is installed instead of a microlens, and an image of a surface emitting laser is displayed as an image optical fiber. And the image is formed on the photodetector.

By adopting the above structures (a) to (d), the surface emitting laser, the optical fiber and the photodetector can send an optical signal without mechanically contacting each other.

FIG. 8 shows a structure in which the surface emitting laser array and the photodetector array are mounted on the same surface of the board. 8-1 is a prism mirror. The surface emitting laser array 4-3 and the photodetector array 4-9 are mounted on the same surface of the board 4-6, but the prism is mounted on the photodetector, and the light beam array incident from the right side is bent. Have an effect.

In the above-described embodiment, the laser array for emitting optical signals and the photodetector array for receiving optical signals are arranged on the entire board, and the optical fiber wiring group is arranged in the space between the boards. A short-distance free-space optical connection is applied to inter-board optical interconnection, and a group of light beams emitted from the laser array of each board is flown into a free space of a few millimeters. By optical wiring, an arbitrary optical wiring is realized, and a light beam group is again flown to a free space of several mm at the end of the optical fiber, and this is received by the detector array of the adjacent board. In order to accurately align the laser array, optical fiber array, and photodetector array, a guide pin and guide hole are provided, and after the board is inserted, the pin is inserted sideways, so that the optical fiber array and surface emitting laser array can be accurately formed. , The photodetector array is aligned, and then the optical fiber array is moved along the guide pin to approach the laser array and the photodetector array to a distance of 5 mm or less, thereby ensuring more optical coupling. I shall. The surface emitting laser is suitable for high speed modulation, and can be modulated at several tens of Gbps at the research level.

[0045]

As described above, according to the present invention,
A surface emitting laser array and a photodetector array are installed on the board, and optical fiber wiring is installed in the space between the boards, and these do not make mechanical contact with each other, but by passing the light beam that has flown into the free space. , To provide mutual coupling, and to ensure the coupling, a movable guide pin is provided, and by limiting the distance to fly the beam in free space to 5 mm or less, an ultra-high capacity, ultra-high-speed inter-board optical beam Interconnection can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a basic concept of an inter-board optical interconnection device according to an embodiment of the present invention.

FIG. 2 is a detailed view of FIG. 1 viewed from the front.

3 is a perspective view showing in detail the structure of an optical connection circuit used in the inter-board optical interconnection device of FIG.

4 is a surface emitting laser array installed on the back surface of the board in the inter-board optical interconnection device of FIG. 1;
It is a figure which partially expands and shows a photodetector array.

5A and 5B are explanatory views showing step by step how a board is inserted and coupled with an optical fiber in the inter-board optical interconnection device of FIG.

FIG. 6 is a diagram showing an optical fiber used in an optical wiring board.

FIG. 7 is an explanatory diagram showing how the optical fiber is coupled to the surface emitting laser array and the photodetector array.

FIG. 8 is a diagram showing a structure in which a surface emitting laser array and a photodetector array are mounted on the same surface of a board.

FIG. 9 is a diagram showing a configuration of a conventional inter-board bus connection using a D-fiber.

FIG. 10 is a diagram showing a structure of a conventional backplane using smart pixels.

FIG. 11 is a diagram showing a conventional inter-board optical bus connection using an optical fiber and a coupler.

FIG. 12 is a diagram showing a conventional inter-board optical interconnection using a hologram.

[Explanation of symbols]

 1-1-a to 1-1-e board 1-2 optical connection circuit 1-3 surface emitting laser array 1-4 surface detector array 1-5 emitted light beam 1-6 guide pin

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H04B 10/12 10/28 10/02 (72) Inventor Shigeki Hino 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (7)

[Claims] 1. An inter-board optical interconnection device for mounting a board on which an electric circuit is mounted in a bookshelf form and exchanging signals between the boards, wherein an optical signal is emitted on the board in addition to the electric circuit. A surface emitting laser array and a surface detector array for receiving the optical signal are mounted, and an optical connection circuit composed of an optical fiber group is arranged between the arrays, and a light beam received at an arbitrary position enters the optical fiber, Between the boards, which is equipped with a mechanism for emitting light at an arbitrary location, characterized in that the surface emitting laser array, the optical fiber optical connection circuit, and the surface detector array are connected by a free space light beam without contacting each other. Optical interconnection device. 2. The light beam emitted from the board is accurately coupled to the optical fiber of the optical connection circuit, and the light beam emitted from the optical fiber of the optical connection circuit is accurately coupled to the photodetector. Therefore, a guide hole for position determination is formed on the board or the optical connection circuit, and a movable guide pin is provided on the board or the optical connection circuit. When the board is inserted, the guide pin is pushed out. The optical fibers are inserted into the guide holes to establish a positional relationship with each other, and then the optical fiber group approaches the surface emitting laser array and the surface detector array along the guide pins. 2. The inter-board optical inter-connector according to claim 1, further comprising a mechanism in which an array interval is 5 mm or less. Device. 3. A plate in which an optical wiring board disposed between the boards has a hole at a position corresponding to a light beam emitted from the board, and an optical fiber having ferrules at both ends for inserting into the hole. 3. The inter-board optical interconnection device according to claim 1, wherein the combination of optical wirings is determined by the combination of inserting the optical fiber into the hole. 4. The board according to any one of claims 1 to 3, wherein a lens or a lens array is provided at a tip of each of the surface emitting laser array, the surface detector array, and the optical fiber array. Optical interconnection device. 5. The inter-board optical interconnection device according to claim 1, wherein the optical fiber is a step index multimode optical fiber having a core diameter of 50 microns or more. 6. The inter-board optical interconnection device according to claim 5, wherein the optical fiber is a plastic optical fiber. 7. The inter-board optical interconnection device according to claim 5, wherein the multi-mode optical fiber is a multi-core image optical fiber.