JP2003098392A - Optical communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical communication device which can communicate in a plurality of channels and is made small and highly reliable. SOLUTION: One end of a multiple flat optical fiber 2 is inserted into a housing 1 housing a plurality of optical elements 27 and an IC chip 25, and the respective optical elements 27 are arranged facing the optical fibers 32 of each core of the multiple flat optical fiber 2. A pig-tail type optical communication device where optical elements and IC chips are intensively arranged for a plurality of channels is thus configured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication device formed by combining an optical fiber, an optical element, and an electric element, and more particularly, an optical communication device capable of multi-channel communication, downsized, and high reliability. It is about.

[0002]

2. Description of the Related Art In optical communication, an optical transmitter and an optical receiver for mutually converting an optical signal in an optical fiber transmission line and an electric signal in a communication processing device are required. An integrated optical transmitter and optical receiver is called an optical transceiver. Here, the optical transmitter, the optical receiver, and the optical transceiver are collectively referred to as an optical communication device.

In general, an optical transceiver, as shown in FIG. 8, has one transmitting section 101 which drives a light emitting module by an electric signal to output an optical signal, and an optical signal which is converted into an electric signal by a light receiving module. One receiver 1 to amplify
It is a combination of 02 and.

The optical transceiver is mounted as a component on a circuit board that performs communication processing. Further, the circuit board is housed in the housing of the communication processing device.

In a conventional optical transceiver, as shown in FIG. 9A, a single optical element 111 is packaged in a package 112.
The optical device module 118 is housed in a package 112 and the leads 113 are attached to the package 112 to form an optical device module 118. The optical device module 118 is used in a form of being mounted on a substrate 119 in an optical transceiver as shown in FIG. ing. Reference numeral 114 is a lens that focuses the light on the optical element, 115 is a mount base that fixes the optical element, and 116 is wire bonding that connects the optical element to the lead. The optical fiber 117 inserted in the package 112 is of the optical fiber integrated type. Further, 109 is a wiring pattern of the optical transceiver board, and 108 is an IC module for processing an electric signal. As shown in FIG. 9C, an IC chip 107 is housed in the IC module 108, and the IC chip 107
The C chip 107 is connected to the lead 105 via the wire bonding 106.

In order to couple the optical fiber of the transmission line to the optical element module 118, as shown in FIG. 10, the housing 122 of the optical transceiver 121 is provided with a receptacle 123 into which an optical fiber connector is inserted. The optical transceiver 121 having such a configuration is called a receptacle type. The optical transceiver 121 is arranged and mounted on the circuit board so that the end surface of the receptacle 123 is located at the end of the circuit board.
The circuit board is arranged so that the end surface of the circuit board opens from the front panel of the housing of the communication processing device. However, it is also possible to realize a pigtail type in which the optical fiber 117 directly coupled to the optical element module is extended from the optical transceiver without using the receptacle and the connector is attached to the optical fiber 117.

As a method of electrically connecting the optical transceiver 121 to the circuit board and mechanically fixing the optical transceiver 121, a lead 124 extending from a housing 122 of the optical transceiver 121 is used.
There is a method of soldering to the circuit board. In the case of the pigtail type, a male and female connector may be mounted on the housing of the optical transceiver and the mating circuit board, and the connectors may be fitted together.

[0008]

The conventional optical transceiver has only one transmitting unit 101 and one receiving unit 102. Therefore, a large number of optical transceivers are used to handle multi-channel communication. To accommodate a large number of optical transceivers in a communication processing device having a limited space, it is necessary to downsize the optical transceivers.
However, the conventional technology has a limit in downsizing the optical transceiver.

For example, the current minimum limit of the receptacle type end face is to have a width of about 13 mm because it is necessary to insert two connectors, and this limits the number of optical transceivers to be arranged at the end of the circuit board. . Even if the size of the receptacle is made smaller by the technology for making the connector smaller, it is not possible to expect a significant reduction in width to approach the pigtail type. Even if the pigtail type is adopted, the optical transceivers cannot be made so small because the packaging density of the optical element modules 118 and the IC modules 108 is limited, and the number of optical transceivers arranged is limited.

In other words, optical components and circuit components such as drivers and amplifiers connected thereto are packaged with through-hole leads or surface mounting leads such as optical element modules and IC modules.
Mounting density cannot be increased.

Further, since circuit components such as a driver used in the transmission unit 101 and circuit components such as an amplifier used in the reception unit 102 have different circuit configurations, it is difficult to incorporate them into one IC. A space is required because ICs for each unit and each receiver are mounted.

Further, even if the transmitters 101 and the receivers 102 can be collectively arranged, a new problem occurs that crosstalk easily occurs when various signal lines come close to each other due to the collective arrangement. To do.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above problems and provide an optical communication device capable of multi-channel communication, miniaturized and highly reliable.

[0014]

In order to achieve the above object, the present invention is to insert one end of a multi-core flat optical fiber into a housing containing a plurality of optical elements and an IC chip,
Each optical element is arranged so as to face the optical fiber of each core of this multicore flat optical fiber.

A single optical element is used as each of the plurality of optical elements, the plurality of single optical elements are arranged side by side on an optical element substrate, and the multicore flat optical fiber is placed on the optical element substrate. It may be placed.

It is also possible that four optical elements are arranged side by side to form an integrated optical element array, and the four element array is placed on the optical element substrate to arrange the plurality of optical elements.

Further, according to the present invention, one end of a multi-core flat optical fiber is inserted into a housing for accommodating a plurality of optical elements and an IC chip, and the optical fiber of each core of the multi-core flat optical fiber is exposed. The optical elements are arranged, the IC chips are arranged behind these optical elements, and the optical element IC chips are connected by wire bonding.

Two signal transmission lines from the IC chip are wired for one signal on the substrate in the housing on which the IC chip is mounted, and the signal logic of one transmission line is inverted from the signal logic of the other transmission line. You may make it transmit.

All of the plurality of optical elements may be light emitting elements, and the IC chip may be a driver for driving the light emitting elements.

All of the plurality of optical elements may be light receiving elements, and the IC chip may be an amplifier for amplifying a light receiving signal.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, in the optical communication device according to the present invention, one end of a multi-core flat optical fiber (also referred to as a tape fiber) 2 is inserted into a housing 1 containing a plurality of optical elements and IC chips. An optical communication device of the pigtail type in which the multicore collective optical connector 3 is attached to the opposite end of the multicore flat optical fiber 2. In the housing 1, each optical element is arranged so as to face the optical fiber of each core of the multicore flat optical fiber 2.

Here, the multicore flat optical fiber 2 is an 8-core flat optical fiber in which 0.25 mm × 8 single mode fibers are arranged in parallel at a pitch of 0.25 mm. One end of the 8-core flat optical fiber 2 is inserted into the housing 1 and fixed in the housing 1. An 8-core collective optical connector 3 is attached to the opposite end of the 8-core flat optical fiber 2.

The housing 1 is made of metal (aluminum) and is formed into a substantially rectangular parallelepiped shape. A release member 4 for tilting the optical communication device when the optical communication device is removed from the host circuit board is provided at the end of the housing 1 opposite to the insertion end of the multi-core flat optical fiber.

Inside the housing 1, a connecting connector 5 is housed so as to face the bottom. This connector 5 is for taking out a signal from the IC chip to the host circuit board 6 outside the housing and fixing the optical communication device to the host circuit board 6. If the connector 5 is a female, the host The mating connector 7 on the circuit board 6 is male. The male and female of the connecting connector 5 and the mating connector 7 may be reversed.

As shown in FIG. 2, the housing 1 of the optical communication device according to the present invention is divided into a lower housing 21 and an upper housing 22 in two parts. Of these, the lower housing 21 is composed of a bottom surface and side walls surrounding the periphery thereof, and forms a space for accommodating the optical communication device substrate 23. The upper housing 22 closes the upper part of the accommodation space and forms a large number of irregularities (not shown) on the surface to radiate heat.

On the optical communication device substrate 23, a wiring pattern is formed on the surface, and an optical element substrate (silicon substrate) 24 and an IC chip 25 are mounted. The connector 5 for connection is attached to the back surface of the optical communication device substrate 23.

A mating connector 7 is provided on the bottom surface of the housing 1.
Is formed with an inlet 26. Since the lower end of the connecting connector 5 is located at substantially the same height as the inlet 26, when the connecting connector 5 is fitted to the mating connector 7, the bottom surface of the housing 1 substantially contacts the host circuit board 6. Become.

A plurality of optical elements 27 are provided on the optical element substrate 24.
Are mounted side by side on a straight line. These optical elements 27
And the IC chip 25 are connected by wire bonding 28. Further, the tip of the multi-core flat optical fiber 2 is placed and fixed on the optical element substrate 24. By closing the upper portion of the lower housing 21 with the upper housing 22, the multicore flat optical fiber 2 is inserted into the housing 1 from the closed portion of the upper and lower housings.

An optical element 27 is arranged in the housing 1 so as to face the insertion end of the multi-core flat optical fiber 2, an IC chip 25 is arranged on the back side of the optical element 27, and further, the IC chip 25 of the IC chip 25 is arranged. The connector 5 for connection is arrange | positioned at the back.

As shown in FIG. 3, inside the optical communication device according to the present invention, eight optical elements 27 are arranged in a line on the optical element substrate 24 with a minimum pitch of 0.5 mm. (Only three are shown in this figure for simplicity). V-grooves 31 are formed in advance on the optical element substrate 24 at the same pitch of 0.5 mm as the arrangement pitch of the optical elements 27. One optical fiber 32 along each V groove 31
, And each optical fiber 32 is fixed to the optical element substrate 24 by adhesion.

Each optical element 27 and each terminal of the IC chip 25 are connected by wire bonding 28. In addition, a wiring pattern 33 is previously formed on the surface of the optical communication device substrate 23.
Are formed, and the wiring pattern 33 is connected to each terminal of the connecting connector 5. And IC chip 2
The terminals 5 and the wiring patterns 33 are connected by wire bonding 34.

Up to now, the optical element 27 was not limited to a light emitting element or a light receiving element, but by using all eight optical elements 27 as light emitting elements and the IC chip 25 as an eight circuit driver, this optical communication is realized. The device is an 8-channel optical transmitter, and all eight optical elements 27 are light receiving elements.
By using the C chip 25 as an 8-circuit amplifier, this optical communication device becomes an 8-channel optical receiver. Also,
The light emitting element and the light receiving element are used in combination, and I
An optical transceiver that performs 4-channel transmission / reception may be formed by mounting the C chip and the IC chip of the amplifier.

Further, the number of channels is set to 8 in accordance with the convention that the computer constituting the communication processing device has a unit of 8, and it goes without saying that another number may be used.

The optical communication device of the present invention shown in FIGS. 1 to 3 is of a pigtail type and uses the single optical element 27 and the IC chip 25, so that the occupied space per circuit can be reduced. Further, since the optical element 27 is arranged so as to face the optical fiber 32 of each core and the IC chip 25 is arranged on the back side of the optical element 27, a narrow optical communication device is formed, and on the host circuit board 6. It becomes possible to arrange them densely. In addition, since the optical element 27 and the IC chip 25 are connected by the wire bonding 28, the number of joints is small, the reliability is high, and the transmission distance in the optical communication device is short. Unnecessary radiation is less likely to be emitted between the insides of the devices, and is less likely to be received.

As a result, it is possible to realize an 8-channel optical transmitter or an optical receiver or an 4-channel transceiving optical transceiver having a size (end face width of about 13 mm) which is almost the same as the conventional 1-channel transceiving optical transceiver. .

Next, the arrangement of the optical elements will be described.

In the arrangement shown in FIG. 4A, eight single optical elements 27 are arranged on the optical element substrate 24 in a row at equal intervals. The optical fibers 32 forming the cores of the 8-core flat optical fiber 2 are arranged at the same pitch as the optical elements 27, and are optically coupled to the optical elements 27 one-to-one.

In the arrangement shown in FIG. 4B, a four-element array 42, in which four optical elements are arranged in a row and integrated, is mounted on each of the two optical element substrates 41, 41. There is. By arranging two 4-element arrays 42 in this manner, eight optical elements are arranged in a line.

When a composite of a large number of elements such as an 8-element array is used, the number of mounting steps can be saved, but the array must be replaced even if one element is defective, resulting in poor yield. On the other hand, when a plurality of single optical elements 27 are used, only the optical element 27 needs to be replaced in the case of a defect, so the yield is improved, but the single optical elements 27 are aligned and mounted one by one. Takes man-hours. 4-element array 42
When using a composite of a small number of elements such as, the probability that one of the elements will be defective is lower than the composite of a large number of elements,
The yield does not drop so much, and the mounting man-hour is reduced, so that the cost can be reduced as a whole. In addition, FIG. 4 (a) using the single optical element 27
Which of the above-mentioned form and the form of FIG. 4B using the 4-element array 42 is superior in cost is judged by comparing the unit price of each component, the yield rate, the mounting man-hour and the unit price. It will be.

The circuit diagram of the optical communication device of the present invention is shown in FIG.
It becomes like (a) or FIG.5 (b). In the circuit shown in FIG. 5A, all eight optical elements 27 are light emitting elements, for example, LD (laser diode) 51, and the IC chip 25 is a drive circuit array 52 of eight circuits. As a result, an 8-channel optical transmitter is realized.

In the circuit shown in FIG. 5B, all eight optical elements 27 are light receiving elements, for example, PDs (photodiodes) 53, and the IC chip 25 is an amplification circuit array 54 of eight circuits. As a result, an 8-channel optical receiver is realized.

In the optical communication device of FIGS. 5A and 5B, the functions of optical elements and circuits are unified, so that a plurality of necessary circuits can be realized by one IC chip 25. . As a result, the number of parts accommodated in the housing is reduced, which leads to downsizing and cost reduction.

Two transmission lines for transmitting and receiving a signal from the IC chip 25 to the host circuit board 6 via the connection connector 5 are wired for one signal. Then, the signal logic of one transmission line is inverted from the signal logic of the other transmission line for transmission. FIG. 6A shows an example of the optical transmitter.

As shown, a signal "data" is output from two adjacent connector terminals 61 and 62 in the connector 5 for connection.
And the signal “data bar” are input for one drive circuit 63. Although the shape of the wiring pattern is not shown, the wiring pattern of the signal "data" and the wiring pattern of the signal "data bar" are provided close to and adjacent to each other, preferably in parallel. The drive circuit 63 causes the LD 51 to emit light only when the signal “data” is 0 and the signal “data bar” is 1, and does not cause the LD 51 to emit with other logics. The signals "data" and "data bar" from the host circuit board 6 always have opposite logics as shown in FIG. 6 (b).

In the case of an optical receiver (not shown), the PD output is input to the amplifier circuit, and the forward / reverse logic signals "data" and "data bar" are output from the amplifier circuit. The wiring pattern of the signal “data” and the wiring pattern of the signal “data bar” are provided close to and adjacent to each other, preferably in parallel, and are connected to two adjacent connector terminals in the connection connector 5.

In this way, two signal transmission lines are wired for one signal and the signals are transmitted with their logics inverted, so that if one of the radiation noises is positive, the other becomes negative,
The radiant spaces slightly apart cancel each other out. This eliminates crosstalk with other signal transmission lines.

Next, a mode in which the optical communication device of the present invention is used in a communication processing apparatus will be described.

As shown in FIG. 7A, the host circuit board 6 is a slot insertion type board having a backboard connector 71 at one end. This host circuit board 6
A plurality of mating connectors 7 are mounted on each of the mating connectors 7, and an optical communication device 72 can be attached to each mating connector 7. The arrangement of the optical communication devices 72 shown in the figure is such that the longitudinal directions of the housings 1 are parallel to each other, and the optical communication devices 72 are arranged in one or more rows near the free end of the host circuit board 6. Housing 1 is a multi-core flat optical fiber 2
Is inserted toward the backboard connector 71, and the multicore collective optical connector 3 on the opposite end of the multicore flat optical fiber 2 extended from this is inserted into the backboard connector 71. A communication processing circuit is mounted between the backboard connector 71 and the optical communication device 72.

Each optical communication device 72 is the 8-channel optical transmitter or the optical receiver described so far,
Since the size is almost the same as that of the channel optical transceiver, if the host circuit board 6 has the same area, four times as many channels as the conventional one can be mounted.

As shown in FIG. 7B, the communication processing device 73 has a multistage slot 74 into which a plurality of boards can be inserted, and a plurality of host circuit boards 6 can be mounted. Of course, a communication processing device including one host circuit board 6 may be configured. An optical fiber cable 75 is wired from the back side of the communication processing device 73 to another communication processing device (not shown). This enables multichannel optical communication with another communication processing device.

FIG. 7C shows a backboard connector 71.
2 shows an example of the connection relationship between the multi-core flat optical fiber 2 from one optical communication device 72 and the optical fiber cable 75 wired from the back side of the communication processing device 73. The multicore flat optical fiber 2 includes an optical transmission line from the first channel ch1 to the Nth channel chN. On the other hand, the optical fiber cable 75
, Each channel is independent, and is wired to a plurality of communication partners 76. In this way, each channel in one optical communication device 72 can be independently wired to any communication processing device. Therefore, when the number of channels required for each communication processing device that is the communication partner 76 is different, it is possible to allocate any channel of the optical communication device 72 to any communication processing device that is the communication partner 76. Become. As a result, for example, it becomes easy to wire a large number of terminals, relay devices, and optical fiber cables from other host devices to the LAN host device.

[0053]

The present invention exhibits the following excellent effects.

(1) Since it is a pigtail type in which a multicore flat optical fiber is inserted in the housing, it is not necessary to secure a width for the receptacle. Further, since a single optical element or IC chip is used and the optical element is arranged so as to face the optical fiber of each core, the occupied space is smaller than that of using the optical element module or IC module. As a result, miniaturization of the optical communication device is achieved.

(2) When a composite of a small number of elements such as a four-element array is used, it is possible to achieve a comprehensive cost reduction because of a reduction in yield due to element failure and a cost factor due to mounting man-hours.

(3) A pigtail type in which a multicore flat optical fiber is inserted, a single optical element or an IC chip is used, and the optical element is arranged so as to face the optical fiber of each core, and the rear side of the optical element is arranged. Since the IC chip is arranged in the optical fiber and the optical element and the IC chip are connected by wire bonding, miniaturization of the optical communication device is achieved.

(4) Optical elements and electric circuits are composed of optical elements and IC chips that are not modularized and are connected by wire bonding. Therefore, compared to conventional products using optical element modules or IC modules, there are fewer joints. Highly reliable. Also, the transmission distance within the optical communication device will be shortened,
It is a structure that is less likely to receive unnecessary radiation and is less likely to be received.

(5) Since two signal transmission lines are wired for one signal and the logics are inverted and transmitted, the radiation noises from both lines are canceled and crosstalk is eliminated.

(6) Since the functions of the optical elements and circuits are unified, a plurality of circuits can be incorporated in one IC chip, and the number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is an external view of an optical communication device showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an optical communication device showing an embodiment of the present invention.

FIG. 3 is an internal structural diagram of an optical communication device showing an embodiment of the present invention.

FIG. 4 is a layout view of an optical element showing an embodiment of the present invention.

FIG. 5 is a circuit diagram of an optical communication device showing an embodiment of the present invention.

FIG. 6A is a circuit diagram of one channel and FIG. 6B is a signal waveform diagram in the optical communication device according to the embodiment of the present invention.

FIG. 7 is (a) a configuration diagram of a host circuit board, (b) a mounting diagram of the host circuit board, and (c) a channel distribution diagram in the communication processing device according to the embodiment of the present invention.

FIG. 8 is a circuit diagram of a conventional optical transceiver.

9A and 9B are (a) an internal structure diagram of an optical element module, (b) a physical layout diagram of an optical transceiver substrate, and (c) an internal structure diagram of an IC module in a conventional optical transceiver.

FIG. 10 is an external view of a conventional optical transceiver.

[Explanation of symbols]

1 housing 2 Multi-core flat optical fiber 5 Connector for connection 6 Host circuit board 7 Mating connector 24 Optical element substrate 25 IC chip 27 Optical element 32 optical fiber 42 4-element array

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiko Kobayashi             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Cable Co., Ltd., Optro System Research Center (72) Inventor Kazuhiro Komatsuzaki             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Cable Co., Ltd., Optro System Research Center (72) Inventor Kenji Mizobuchi             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Cable Co., Ltd., Optro System Research Center F-term (reference) 2H037 AA01 BA02 BA11 DA03 DA04                       DA06 DA12

Claims (7)

[Claims] 1. An end of a multi-core flat optical fiber is inserted into a housing that houses a plurality of optical elements and an IC chip, and each optical element is exposed by facing the optical fiber of each core of the multi-core flat optical fiber. An optical communication device characterized by being arranged. 2. A single optical element is used as each of the plurality of optical elements, and the plurality of single optical elements are arranged side by side on an optical element substrate, and the multi-core flat light is placed on the optical element substrate. The fiber is mounted, The claim 1 characterized by the above-mentioned.
The optical communication device described. 3. An optical element array in which four of the optical elements are arranged side by side to form an integrated optical element array, and the four element array is placed on a substrate for an optical element to arrange the plurality of optical elements. The optical communication device according to claim 1. 4. An end of a multicore flat optical fiber is inserted into a housing for accommodating a plurality of optical elements and an IC chip, and the optical element is exposed by facing each core optical fiber of the multicore flat optical fiber. An optical communication device characterized in that the IC chips are arranged at the back side of these optical elements, and the optical element IC chips are connected by wire bonding. 5. Two signal transmission lines from the IC chip are wired for one signal on a substrate in the housing on which the IC chip is mounted, and the signal logic of one transmission line is the signal logic of the other transmission line. 5. The optical communication device according to claim 4, wherein the optical communication device is inverted and transmitted. 6. The plurality of optical elements are all light emitting elements,
The optical communication device according to claim 4 or 5, wherein the IC chip is a driver for driving a light emitting element. 7. The plurality of optical elements are all light receiving elements,
The optical communication device according to claim 4 or 5, wherein the IC chip is an amplifier that amplifies a light reception signal.