JPH09181676A - Optical transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform miniaturization, to lower a price and to perform highly reliable optical communication by providing a monitoring part and an arithmetic part for eliminating a signal leakage interference part from optical transmission signals to optical reception signals in the transmitter-receiver of a single core two-way optical communication channel. SOLUTION: The optical signals L1 of a light emission part 12 are reflected vertically upwards at the semi-transmissive mirror 141 of an optical element 14, led to an optical fiber and transmitted, reception signals L2 are obliquely transmitted at the mirror 141 and made incident on a light reception part 231 and a part of the signals L1 is also leaked to the light reception part 231 as stray light. The monitoring part 232 receives only the stray light and the detection current and the detection current of the light reception part 231 are inputted to the arithmetic part 26 provided with current/voltage conversion circuits 261 and 262 and a differential amplifier circuit 263 and computed. The arithmetic part 26 electrically offsets the stray light by the adjustment of transimpedance and gain and eliminates the signal leakage interference part and the highly reliable optical communication is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmitter / receiver for transmitting and receiving an optical signal, which is provided in, for example, a one-fiber bidirectional communication line.

[0002]

2. Description of the Related Art As a method for transmitting and receiving a signal by optical communication, there is a one-core bidirectional communication line method using one optical fiber or a two-core bidirectional communication line method using two optical fibers. is there. FIG. 7 is a diagram showing an example of a one-core bidirectional communication line system.
And the other optical transmission device 2 are connected by one optical fiber F.

In this one-core bidirectional communication line system,
As shown in FIG. 8, one optical transmission device 1 includes a light emitting element 3, a light receiving element 4, a directional coupler 5, a lens, and the like, and is a light emitting element that is a separate component for the housing. 3, the light receiving element 4, the directional coupler 5, the lens and the like are assembled and configured. Similarly, the other optical transmission device 2 also has a light emitting element 3, a light receiving element 4, a directional coupler 5, a lens, and the like.

[0004]

In the conventional one-core bidirectional communication line system, the optical transmission equipment must be composed of separate light emitting element 3, light receiving element 4, directional coupler 5 and lens. This is a major obstacle to reliability, downsizing and price reduction.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical transmitter / receiver capable of miniaturization and cost reduction and capable of highly reliable optical communication. .

[0006]

According to the present invention, there is provided an optical transmitter / receiver for transmitting / receiving an optical signal,
When transmitting the first optical signal and receiving the second optical signal at the same time, the signal leakage interference of the first optical signal and the second optical signal is detected by the supervisory signal of the first optical signal. This is achieved by providing an arithmetic unit for removing.

According to the above arrangement, the monitoring section monitors the optical signal and the arithmetic section removes the signal leakage interference of the optical signal, so that the reliability of the optical communication can be improved.

[0008]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Although the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are given. However, the scope of the present invention is not limited to the following description. It is not limited to these forms unless otherwise stated.

First, before describing the embodiment of the optical transmitter / receiver of the present invention, the technology on which it is based will be described with reference to FIGS. 5 and 6. FIG. 5 is a perspective view showing an embodiment of an optical transmitter / receiver, which is a base technology of the embodiment of the optical transmitter / receiver of the present invention, and FIG. 6 is a side view and a plan view thereof. The optical transceiver 10 includes a substrate 11 and a light emitting unit 1.
2, the light receiving unit 13, the optical element 14, the semiconductor element 15, the arithmetic unit 16 and the coupling lens 17, and preferably the light emitting unit 1.
It has a light receiving part for monitoring the optical signal transmitted from the optical fiber 2 and is provided in the one-core bidirectional optical communication line to transmit the first optical signal and receive the second optical signal.

The substrate 11 is made of, for example, a silicon (Si) semiconductor or a gallium arsenide (GaAs) semiconductor, and an upper surface 11a of the substrate 11 is provided with a light receiving section 13, an optical element 14, a semiconductor element 15 and a computing section 16. There is. Also,
The light emitting unit 12 and the monitor light receiving unit are provided on the upper surface 15 a of the semiconductor element 15.

As the optical element 14, for example, a prism (micro prism or trapezoidal prism) or a beam splitter is used. On one side of the optical element 14, an inclined semi-transmissive mirror 141 is formed. The inclination angle of the semi-transmissive mirror 141 is preferably, for example, the substrate 1
It is formed at 45 ° with respect to the plane of 1. Then, the coupling lens 17 is provided above the semi-transmissive mirror 141.
Is arranged.

The light emitting section 12 is, for example, a laser diode, and is arranged so that the transmitting section for transmitting the first optical signal L1 faces the semi-transmissive mirror 141 of the optical element 14. Then, the monitor light receiving portion is provided so as to be able to receive the laser light for monitoring emitted from the rear side of the transmitting portion.

The light receiving portion 13 is, for example, a photodiode and is provided below the optical element 14. The calculation unit 16 includes a current / voltage conversion circuit 161, and the light receiving unit 1
It is connected to the light receiving unit 13 in order to convert the detection current due to the light reception at 3 into a voltage.

Next, the operation of the above-mentioned optical transceiver will be described. First, the first optical signal L1 from the light emitting unit 12
Is refracted and reflected vertically upward by the semi-transmissive mirror 141 of the optical element 14, is focused by the coupling lens 17, and is guided to the incident end face of the optical fiber forming the one-core bidirectional optical communication line. At this time, the transmission state of the first optical signal L1 of the light emitting unit 12 is monitored by the monitoring light receiving unit,
The second drive circuit 18 is controlled. Then, the first optical signal L1 passes through the optical fiber and is guided to a remote optical transmitter / receiver having the same configuration as that shown in FIGS.

On the other hand, the second optical signal L2 transmitted from the remote optical transmitter / receiver through the optical fiber is refracted and transmitted obliquely by the semi-transmissive mirror 141 of the optical element 14 via the coupling lens 17. Light receiving section 1 under the optical element 14
3 is incident. At this time, part of the second optical signal L2 is reflected by the semi-transmissive mirror 141 and is incident on the light emitting unit 12 side. Is laser light from another remote optical transmitter / receiver, and therefore is incoherent with respect to the light emitting unit 12, and does not interfere with the first optical signal L1 of the light emitting unit 12, and thus the first light signal L1 It does not affect the transmission of the optical signal L1.
Then, the detected current by the light reception from the light receiving unit 13 is input to the current / voltage conversion circuit 161 of the calculation unit 16, converted into a voltage, and output.

As described above, the semi-transmissive mirror 141 of the optical element 14 reflects the first optical signal L1 and transmits the second optical signal L2 according to the polarization component of the light. That is, the first
There is a polarization component difference between the optical signal L1 and the second optical signal L2, which distinguishes reflection / transmission. But,
In most cases, the actual difference in the polarization components is very small, and thus the distinction between reflection and transmission may not be made completely. In such a case, a part of the first optical signal L1 is partially transmitted by the semi-transmissive mirror 14
1 is transmitted and leaks to the light receiving part 13 and its periphery. Further, a part of the second optical signal L2 is reflected by the semi-transmissive mirror 141 and leaks to the optical fiber and its periphery. Of these, the first optical signal L leaking to the light receiving unit 13 and its surroundings.
Part of 1 (hereinafter referred to as stray light) becomes a problem. That is, as shown in the enlarged view of the light receiving unit 13 in FIG. 6B, the detected current from the light receiving unit 13 is the amount of received light S of the second optical signal L2 interfered by the received amount N of stray light. Therefore, there is a problem that the detection accuracy decreases.

Therefore, the following has been developed as an optical transmitter-receiver for solving the above problems. 1 is a perspective view showing a first embodiment of an optical transmitter / receiver of the present invention, and FIG. 2 is a side view and a plan view thereof. The optical transmitter / receiver 20 has almost the same configuration as the optical transmitter / receiver shown in FIG. 5, except that a monitoring light receiving portion 232 formed of, for example, a photodiode is provided in parallel with the light receiving portion 231. The point is that the unit 26 calculates the detection signal from the light receiving unit 231 and the monitoring signal from the monitoring light receiving unit 232.

As shown in the enlarged view of the light receiving section 231 and the monitoring light receiving section 232 in FIG. 2B, the light receiving section 231 is arranged so as to receive the second optical signal L2 and stray light, and the monitoring light receiving section 231 is provided. 232 is arranged so as to receive only stray light, as shown in the enlarged view of the light receiving unit 231 and the monitoring light receiving unit 232 in FIG. The calculation unit 26 includes a light receiving unit 231.
The current / voltage conversion circuits 261, 262 and the current / voltage conversion circuit 26 for converting the detected current due to the received light at the monitor and the monitored detected current due to the received light at the monitor light receiving unit 232 into voltage, respectively.
The differential amplifier circuit 263 is provided for obtaining the difference between the respective voltages from Nos. 1 and 262 and amplifying it. The current / voltage conversion circuit 26
The differential amplifier circuit 263 may directly calculate the detection currents due to the light reception at the light receiving unit 231 and the monitoring detection currents due to the light reception at the monitoring light receiving unit 232.

The processing of the light receiving section 231, the monitoring light receiving section 232, and the computing section 26 in such a configuration will be described. The light receiving amount of the second optical signal L2 received by the light receiving unit 231 is S, the light receiving amount of stray light is N1, and the light receiving amount of stray light received by the monitoring light receiving unit 232 is N2. Then, N1: N2 can be regarded as constant, so N2 / N1 = K is set.

Here, the light / current conversion efficiency of the light receiving section 231 is A1, the light / current conversion efficiency of the monitoring light receiving section 232 is A2,
The transimpedance of the current / voltage conversion circuits 261 and 262 is Z1 with respect to the output of the light receiving unit 231, and the monitoring light receiving unit 2
When the output of the differential amplifier circuit 263 is Z2, the gain of the differential amplifier circuit 263 is + G1 with respect to the output of the light receiving unit 231, and the gain of the monitor light receiving unit 232 is −G2, the output O of the differential amplifier circuit 263 is O.
P is represented by Formula 1.

[Equation 1] Here, if A1 · Z1 · G1 = K · A2 · Z2 · G2, the second term of Formula 1 can be omitted.
It is represented by The omitted second term is stray light.

[Equation 2]

In this way, the current / voltage conversion circuit 261,
262 transimpedance and differential amplifier circuit 26
By adjusting the gain of 3, stray light can be electrically canceled. Here, if the monitor detection current of the monitor light receiving section 232 is fed back to the drive circuit 18, the light emitting section 12 can be subjected to automatic output adjustment.

As described above, when stray light is sent to the light receiving unit 12 and the monitoring light receiving unit 232 at a ratio of 2: 1, N2 / N1 = K =
It becomes 1/2, so 2 · A1 · Z1 · G1 = A2 · Z2
・ G2. In particular, if A1 = A2 and Z1 = Z2, then 2
・ G1 = G2. When stray light is sent to the light receiving unit 12 and the monitoring light receiving unit 232 at a ratio of 1: 2, N2 / N1 = K
= 2, so A1 · Z1 · G1 = 2 · A2 · Z2 ·
It becomes G2. In particular, if A1 = A2 and Z1 = Z2, then G1
= 2 · G2.

In the first embodiment of the optical transmitter / receiver of the present invention described above, the monitor light receiving section 232 is provided on the substrate 11, but the present invention is not limited to this. FIG.
(A) And (B) is a perspective view and a side view showing a 2nd embodiment of an optical transceiver of this invention. The optical transmitter / receiver 30 has substantially the same configuration as the optical transmitter / receiver 20 shown in FIG. 1 except that the second optical element 34, which is, for example, a prism or a beam splitter, is arranged in parallel with the optical element 14 on the substrate 11. And a monitoring light receiving section 33 formed of a photodiode, for example, is provided vertically above the semi-transmissive mirror 341 of the second optical element 34. The second optical element 34 reflects part of the first optical signal L1 from the light emitting section 12 vertically upward by the semi-transmissive mirror 341 and guides it to the monitoring light receiving section 33.

In the first embodiment of the optical transmitter / receiver of the present invention, a light receiving element such as a photodiode is used as the monitor light receiving section 232, but the invention is not limited to this. FIG. 4 is a plan view showing a third embodiment of the optical transmitter / receiver according to the present invention. The optical transmitter / receiver 40 has almost the same configuration as the optical transmitter / receiver 20 shown in FIG. Monitoring amplifier circuit 36 connected to the current / voltage conversion circuit 262.
2 is provided. The distribution circuit 361 is configured to distribute a part of the first optical signal L1 before being optically modulated by the light emitting section 12 to the drive circuit 18 and the monitoring amplification circuit 362.

By the way, although the optical transmitter-receiver of the present invention is applied to the one-core bidirectional communication line in the above-mentioned embodiment, it is not limited to this. For example, if it is applied to an optical disc device using an optical disc, a hybrid optical transmission device is used. High reliability can be obtained as an integrated circuit. It can also be applied to a relay amplifier and a duplexer.

[0026]

As described above, according to the present invention,
The size and cost can be reduced, and optical communication can be performed with high reliability.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of an optical transceiver according to the present invention.

2A and 2B are a side view and a plan view of the optical transceiver shown in FIG.

FIG. 3 is a perspective view showing a second embodiment of the optical transceiver according to the present invention.

FIG. 4 is a perspective view showing a third embodiment of the optical transceiver according to the present invention.

FIG. 5 is a perspective view showing an embodiment of an optical transmitter / receiver, which is a premise of the embodiment of the optical transmitter / receiver of the present invention.

6A and 6B are a side view and a plan view of the optical transceiver shown in FIG.

FIG. 7 is a diagram showing a conventional one-core bidirectional communication line system.

FIG. 8 is a diagram showing a configuration of a conventional one-core bidirectional communication line.

[Explanation of symbols]

10, 20, 30, 40 Optical transmitter / receiver 11 Substrate 12 Light emitting part 13, 231 Light receiving part 14, 34 Optical element 15 Semiconductor element 16, 26, 36 Computing part 17 Coupling lens 18 Driving circuit 232, 33 Monitoring light receiving part 261, 262 Current / voltage conversion circuit 263 Differential amplification circuit 361 Distribution circuit 362 Monitoring amplification circuit L1 First optical signal L2 Second optical signal

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[Procedure amendment]

[Submission date] March 5, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmitter / receiver for transmitting and receiving an optical signal, which is provided in, for example, a one- core bidirectional communication line.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art As methods of transmitting and receiving signals via optical communication, two-way communication line system of one single fiber system using an optical fiber or a bidirectional communication line system of the two two-core method using an optical fiber, There is. FIG. 7 is a diagram showing an example of a one- core bidirectional communication line system, and one optical transmission device 1
And the other optical transmission device 2 are connected by one optical fiber F.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction contents]

In this one- core bidirectional communication line system,
As shown in FIG. 8, one optical transmission device 1 includes a light emitting element 3, a light receiving element 4, a directional coupler 5, a lens, and the like, and is a light emitting element that is a separate component for the housing. 3, the light receiving element 4, the directional coupler 5, the lens and the like are assembled and configured. Similarly, the other optical transmission device 2 also has a light emitting element 3, a light receiving element 4, a directional coupler 5, a lens, and the like.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

In the conventional one- core bidirectional communication line system, the optical transmission equipment must be composed of separate light emitting element 3, light receiving element 4, directional coupler 5 and lens. However, it is a major obstacle to reliability, downsizing, and price reduction.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

According to the present invention, there is provided an optical transmitter-receiver for transmitting and receiving an optical signal, which is provided in a one-core bidirectional optical communication line. A reception unit that removes a signal leakage interference component from the first optical signal to the second optical signal by the monitoring signal of the first optical signal when simultaneously receiving the second optical signal . Achieved by

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

First, before describing the embodiment of the optical transmitter / receiver of the present invention, the technology on which it is based will be described with reference to FIGS. 5 and 6. FIG. 5 is a perspective view showing an embodiment of an optical transmitter / receiver, which is a base technology of the embodiment of the optical transmitter / receiver of the present invention, and FIG. 6 is a side view and a plan view thereof. The optical transceiver 10 includes a substrate 11 and a light emitting unit 1.
2, the light receiving unit 13, the optical element 14, the semiconductor element 15, the arithmetic unit 16 and the coupling lens 17, and preferably the light emitting unit 1.
It has a light receiving part for monitoring the optical signal transmitted from the optical fiber 2 and is provided in the one- core bidirectional optical communication line to transmit the first optical signal and receive the second optical signal.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

Next, the operation of the above-mentioned optical transceiver will be described. First, the first optical signal L1 from the light emitting unit 12
Is refracted and reflected vertically upward by the semi-transmissive mirror 141 of the optical element 14, is focused by the coupling lens 17, and is guided to the incident end face of the optical fiber forming the one- core bidirectional optical communication line. At this time, the transmission state of the first optical signal L1 of the light emitting unit 12 is monitored by the monitoring light receiving unit,
The second drive circuit 18 is controlled. Then, the first optical signal L1 passes through the optical fiber and is guided to a remote optical transmitter / receiver having the same configuration as that shown in FIGS.

[Procedure amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction contents]

FIG. 7 is a diagram showing a conventional one- core bidirectional communication line system.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] Fig. 8

[Correction method] Change

[Correction contents]

FIG. 8 is a diagram showing a configuration of a conventional one- core bidirectional communication line.

[Procedure amendment 12]

[Document name to be amended] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction contents]

FIG. 7

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Claims (4)

[Claims] 1. An optical transmission / reception device for transmitting / receiving an optical signal, wherein the first optical signal is monitored by the first optical signal when the first optical signal is transmitted and the second optical signal is received at the same time. An optical transmission / reception device comprising: an arithmetic unit that removes a signal leakage interference component of the optical signal and the second optical signal. 2. An optical transmitter / receiver for transmitting and receiving an optical signal, a substrate, a light emitting unit provided on the substrate for transmitting a first optical signal, and a second light provided on the substrate. A light receiving portion for receiving a signal; and a light receiving portion provided on the substrate for giving the first optical signal from the light emitting portion to the communication line and receiving the second optical signal from the communication line. An optical element that guides the first optical signal, a monitoring unit for monitoring the first optical signal, and a substrate provided on the substrate to calculate a monitoring signal from the monitoring unit and a detection signal from the light receiving unit. An optical transmission / reception device comprising: a calculation unit that removes a signal leakage interference component of the first optical signal and the second optical signal. 3. The optical transceiver according to claim 2, wherein the monitor is provided on the substrate. 4. The optical transceiver according to claim 2, wherein the monitoring section is provided in the arithmetic section.