JP2003008520A - Two-way optical transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-way optical transmitter that facilitates two-way optical transmission with a simple configuration. SOLUTION: The two-way optical transmitters 10, 20 are interconnected by optical transmission lines 31, 32 and provided with optical transmission sections 12, 22 that convert an electric signal sent from communication nodes 11, 21 into an optical signal and transmit the optical signal, and optical reception sections 13, 23 that convert the received optical signal into an electric signal and transmit the electric signal to the communication nodes 11, 21. Electric switches 14, 15, 24, 25 are respectively provided in a prestage of the optical transmission sections 12, 22 and a poststage of the optical reception sections 13, 23 of the two-way optical transmitters 10, 20, and the electric switches at the poststage of the optical reception sections are brought into a high impedance when the optical signal is transmitted and the electric switches at the prestage of the optical transmission sections are brought into a high impedance when the optical signal is received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional optical transmission device configured to send an optical signal to an optical transmission line and receive an optical signal from the optical transmission line.

[0002]

2. Description of the Related Art With the recent improvement in semiconductor process technology, the performance of semiconductor devices has dramatically improved. However, in an electric circuit that connects these semiconductor elements, the operation speed is limited by a signal delay caused by capacitance between wirings or wiring resistance, or electromagnetic noise (EMI: Electromagnetic
The issue of "Interference" is becoming ignorable. Therefore, attention has been paid to in-board optical interconnection, in which semiconductor elements are connected by optical wiring. This technique proposes an electro-optical hybrid board including a medium having an optical wiring function on a conventional printed board on which electric wiring is performed.

For example, Japanese Patent Laid-Open No. 2000-147270 discloses a printed wiring board having an optical wiring function. This technique is intended to embed an optical fiber or an optical waveguide in an insulating layer of a printed wiring board so that electrical / optical wiring can be made compact and easy. Here, the optical fiber and the optical waveguide are basically premised on one-to-one communication,
For example, when a signal is transmitted bidirectionally like a data line of a memory bus, it is necessary to prepare a transmission line and a photoelectric conversion circuit according to the transmission direction. As means for solving this problem, for example, in Japanese Patent Laid-Open No. 7-79202,
An optical transmission / reception circuit is disclosed that enables bidirectional optical communication with a simple configuration without using a coupler at a connection point with an optical fiber. In this technology, the bias applied to the laser diode can be switched between forward bias and reverse bias, and this laser diode is used as a transmitter element when forward biased and as a photodiode when reverse biased. Is.

[0004]

However, as more multi-bit signal transmission is desired, miniaturization of the optical transmission line,
Low power consumption is essential, and there is a limit to conventional optical transmission lines using optical fibers and optical waveguides. Further, in driving an optical element, it is necessary to improve the characteristics of each of the light emitting element and the light receiving element, but giving a condition that the optical element also serves to receive and emit light may slow down the speed of element development. I have a problem with.

Therefore, an object of the present invention is to provide a bidirectional optical transmission device which facilitates bidirectional optical transmission with a simple structure.

[0006]

The above-mentioned object is to convert an electric signal sent from an upper layer into an optical signal and send it to an optical transmission line, and an optical signal received from the optical transmission line. A bidirectional optical transmission device including an optical receiving unit that converts the optical transmission to an upper layer and sends the optical receiving unit to an upper layer, the bidirectional optical transmission device including an electrical switch at a stage before the optical transmitting unit and at a stage subsequent to the optical receiving unit. Is achieved by Here, when the optical transmitter outputs an optical signal, the electrical switch in the latter stage of the optical receiver is set to high impedance, and when the optical receiver receives the optical signal, the electrical switch in the front stage of the optical transmitter is set. It is preferable to make the static switch high impedance.

In the bidirectional optical transmission system according to the present invention, an optical transmission unit for converting an electric signal sent from an upper layer into an optical signal and transmitting the optical signal, and an optical transmission unit for converting a received optical signal into an electric signal and transmitting the electric signal A plurality of optical transmission devices each having an optical receiving unit for sending to a layer are connected via an optical transmission line, and the optical transmission device is provided at a front stage of the optical transmitting unit and a rear stage of the optical receiving unit, respectively. It is equipped with an electrical switch.

Here, the optical transmission lines may be separate optical transmission lines for transmission and reception, or may be common optical transmission lines for transmission and reception. This common optical transmission line preferably comprises a diffusion optical system for diffusing an optical signal. Further, the optical transmission device sets the electrical switch in the latter stage of the optical receiving unit to high impedance when transmitting the optical signal, and sets the electrical switch in the front stage of the optical transmitting unit to high impedance when receiving the optical signal. Is preferred. With such a configuration, it is possible to obtain a bidirectional optical transmission device that enables bidirectional optical transmission with a simple configuration.

[0009]

FIG. 1 is a diagram showing an embodiment of a bidirectional optical transmission apparatus according to the present invention. In this embodiment, as shown, a plurality of bidirectional optical transmission devices 10 and 20 are connected via optical transmission lines 31 and 32 to form a bidirectional optical transmission system. For the optical transmission lines 31 and 32, for example, individual optical fibers can be used.

The optical transmission device 10 includes an optical transmission unit 12 which converts an electric signal sent from a communication node 11 which is an upper layer into an optical signal and sends the optical signal, and an optical transmission unit 12 which converts a received optical signal into an electric signal and an upper layer. And an optical receiver 13 for sending the signal to the receiver 11. The optical transmitter 12 includes a laser diode (LD) 121 that converts an electric signal into an optical signal, and a laser diode drive circuit (LDD) 122 that drives the LD. Also,
The optical receiving unit 13 includes a photodiode (PD) 131 that converts an optical signal into an electric signal, and an amplifier (Amp) 132 that amplifies the electric signal obtained from the PD. Further, electrical switches 14 and 15 are provided in the front stage of the optical transmitter 12 and the rear stage of the optical receiver 13, respectively.

The optical transmission device 20 includes an optical transmission unit 22 which converts an electric signal sent from a communication node 21 which is an upper layer into an optical signal and sends the optical signal, and an optical transmission unit 22 which converts a received optical signal into an electric signal and an upper layer. 21 and a light receiving section 23 for sending to 21. The optical transmitter 22 includes an LD 221 that converts an electric signal into an optical signal, and an LDD 222 that drives the LD. In addition, the optical receiver 23 is a PD that converts an optical signal into an electrical signal.
231 and an amplifier 232 for amplifying the electric signal obtained from the PD. Further, electrical switches 24 and 25 are provided in the front stage of the optical transmitter 22 and the rear stage of the optical receiver 23, respectively.

Next, the operation of this embodiment will be described.
First, when the optical transmission device 10 transmits an optical signal, the electrical switch 15 in the subsequent stage of the optical receiver 13 is set to high impedance by a control device (not shown). Further, in the optical transmission device 20, in order to receive the optical signal, the electrical switch 24 in the preceding stage of the optical transmission unit 22 is set to high impedance by a control device (not shown). On the other hand, the electric switches 14 and 25 are set to low impedance or closed.

Therefore, in the optical transmission device 10, the electric signal sent from the communication node 11 is input to the optical transmission section 12. In the optical transmitter 12, the LD 121 is driven by the LDD 122 based on this electric signal, and the LD 1
An optical signal is sent from 21 to the optical transmission line 31. here,
Since the electrical switch 15 on the side of the optical receiver 13 has high impedance as described above, no electrical signal is transmitted to the optical receiver 13. On the other hand, in the optical transmission device 20, the PD 231 of the optical receiver 23 receives an optical signal via the optical transmission line 31 and converts it into an electrical signal. The amplifier 232 amplifies this electric signal and transmits it to the communication node 21, which is an upper layer. Here, the electrical switch 24 on the optical transmitter 22 side
Is high impedance as described above, the optical transmitter 2
No electrical signal is transmitted to 2.

Also, when the optical transmission device 20 sends an optical signal, the opening and closing control of the electrical switch is performed in the same manner as described above, and the optical signal is transmitted and received. As described above, in this embodiment, the electric switch is provided in each of the front stage of the LDD and the rear stage of the amplifier, and when transmitting a signal, the switch on the LDD side is closed and the switch on the amplifier side is opened. Reverse when receiving. At this time, the output when the switch is opened is held at high impedance, so that the other signal line can be prevented from being affected.

FIG. 2 is a diagram showing another embodiment of the bidirectional optical transmission apparatus according to the present invention. Compared with the embodiment of FIG. 1, this embodiment is similar in the majority of the configuration as shown, but the two-way optical transmission devices 10 and 20 have common optical transmission paths for transmission and reception. They are different in that they are connected via a (common light guide path) 40.

FIG. 3 is a diagram showing an example of this common light guide path. The common light guide path 40 has a flat plate-shaped transparent medium 41 that forms a core for transmitting an optical signal. Further, preferably, diffusion optical systems 42 and 43 for diffusing an optical signal are provided at the connecting portions between the LDs 121 and 221 and the translucent medium 41, respectively. In the common light guide 40 configured in this manner, L
When the optical signal enters from D121, the optical signal is diffused by the diffusing optical system 42 and widely reaches the facing surface, and is received by the PD 231 on the facing surface. When a plurality of PDs are provided on the opposite surfaces, the same optical signal can be received by each PD. That is, one-to-many broadcast transmission becomes possible. Similarly, when an optical signal is incident from the LD 221, the optical signal is transmitted to the diffusion optical system 4 as well.
3 diffuses to reach the opposite surface widely, and PD of the opposite surface
It is received at 131. Also in this case, a plurality of PDs are provided on the facing surface.
, The PD can receive the same optical signal. Although not shown here, an optical fiber may be interposed between each LD and PD and the transparent medium 41, and the common light guide path 40 may be of an optical coupler type.

Next, returning to FIG. 2, the description will be continued. In the embodiment of FIG. 2, as in the embodiment of FIG.
However, when transmitting an optical signal, the electric switch 15 in the subsequent stage of the optical receiver 13 is set to high impedance by a control device (not shown). Further, in the optical transmission device 20, in order to receive the optical signal, the electrical switch 24 in the preceding stage of the optical transmission unit 22 is set to high impedance by a control device (not shown). On the other hand, the electric switches 14 and 25 are set to low impedance or closed.

Therefore, in the optical transmission device 10, the electric signal sent from the communication node 11 is input to the optical transmission section 12. In the optical transmitter 12, the LD 121 is driven by the LDD 122 based on this electric signal, and the LD 1
An optical signal is sent from 21 to the common light guide 40. Here, since the electrical switch 15 on the side of the optical receiver 13 has high impedance as described above, no electrical signal is transmitted to the optical receiver 13. On the other hand, in the optical transmission device 20, the PD 231 of the optical receiver 23 receives an optical signal via the common light guide 40 and converts it into an electrical signal. Amplifier 23
2 amplifies this electric signal, and communication node 2 which is an upper layer
Propagate to 1. Here, since the electrical switch 24 on the side of the optical transmitter 22 has high impedance as described above, no electrical signal is transmitted to the optical transmitter 22.

Also, when the optical transmission device 20 sends an optical signal, the opening / closing control of the electrical switch is performed in the same manner as described above, and the optical signal is transmitted / received. Two optical transmission devices 10 and 20 are connected to the common light guide 40 of this embodiment, but three or more optical transmission devices can be connected. The common light guide path 40 is a broadcast type transmission path as described above, and an optical signal emitted from one LD can be received by a plurality of PDs. Further, the shape of the common light guide 40 is not limited to that of the embodiment of FIG. 3, and may be, for example, a light guide having a stepwise entrance / exit.

As described above, according to the present invention, optical transmission can be performed with a simple structure in the electric wiring such as a memory bus which performs bidirectional transmission. In addition, by sharing the light guide path, each communication node can be made one-to-one with the conventional optical fiber.
Compared with the case of connecting with, it can be much smaller. Further, the provision of the diffusion optical system in the common light guide path facilitates the broadcast transmission required for bus connection.

[0021]

According to the present invention, it is possible to obtain a bidirectional optical transmission device which facilitates bidirectional optical transmission with a simple structure.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a bidirectional optical transmission device according to the present invention.

FIG. 2 is a diagram showing another embodiment of the bidirectional optical transmission device according to the present invention.

FIG. 3 is a diagram showing an example of a common light guide path.

[Explanation of symbols]

10,20 Optical transmission equipment 11,21 Communication node 12,22 Optical transmitter 13,23 Optical receiver 14,15,24,25 electrical switch 31, 32 Optical transmission line 121,221 Laser diode (LD) 122,222 Laser diode drive circuit (LDD) 131,231 Photodiodes (PD) 132,232 Amp (Amp)

Continued front page    (72) Inventor Ken Uemura             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Hidenori Yamada             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Junji Okada             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Shinya Kyozuka             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Kazuhiro Sakai             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Tsutomu Hamada             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Nori Takanashi             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Masaaki Miura             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Takehiro Niitsu             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Tomao Baba             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Shoji Hisada             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Kenichi Kobayashi             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. (72) Inventor Akira Toshima             430 Green, Sakai, Nakai-cho, Ashigaragami-gun, Kanagawa Prefecture             Inside of Fuji Xerox Co., Ltd. F-term (reference) 5F073 BA01 EA27 EA29 FA05 GA17                 5F088 BA03 BA15 BB01 EA08 EA09                       JA14 KA03 KA10                 5K002 AA01 AA03 BA13 DA04 FA01

Claims (7)

[Claims] 1. An optical transmitter that converts an electric signal sent from an upper layer into an optical signal and sends the optical signal to an optical transmission line, and an optical signal received from the optical transmission line into an electric signal and sends the electric signal to an upper layer. A bidirectional optical transmission device comprising an optical receiving unit, wherein an electric switch is provided at a stage before the optical transmitting unit and a stage after the optical receiving unit, respectively. 2. When the optical transmitter outputs an optical signal, the electrical switch in the latter stage of the optical receiver is set to high impedance, and when the optical receiver receives the optical signal, the former stage of the optical transmitter. 2. The bidirectional optical transmission device according to claim 1, wherein the electrical switch is set to high impedance. 3. A plurality of optical transmitters comprising: an optical transmitter for converting an electric signal sent from an upper layer into an optical signal and transmitting the optical signal; and an optical receiver for converting a received optical signal into an electric signal and transmitting the electric signal to an upper layer. Is a bidirectional optical transmission system in which the optical transmission device is connected via an optical transmission path, and the optical transmission device includes an electric switch in a front stage of the optical transmission unit and a rear stage of the optical reception unit, respectively. A bidirectional optical transmission system characterized by. 4. The bidirectional optical transmission system according to claim 3, wherein the optical transmission lines are separate optical transmission lines for transmission and reception. 5. The bidirectional optical transmission system according to claim 3, wherein the optical transmission line is a common optical transmission line for transmission and reception. 6. The bidirectional optical transmission system according to claim 5, wherein the common transmission line comprises a diffusion optical system for diffusing an optical signal. 7. The optical transmission apparatus sets an electric switch in a subsequent stage of the optical receiving unit to high impedance when transmitting an optical signal, and sets an electric switch in a preceding stage of the optical transmitting unit when receiving an optical signal. The bidirectional optical transmission system according to any one of claims 3 to 6, wherein is set to high impedance.