JPH08213968A - Optical wavelength multiplex communication system - Google Patents

Abstract

PURPOSE: To simplify the constitution and optical adjustment procedures of the optical circuit in each communication mode by providing a selecting means, which selects the optical carrier arriving at an optical transmission line, and an optical modulation means which modulates light having the same wavelength as the selected optical carrier. CONSTITUTION: Optical carriers 43 to 43 transmitted to communication nodes 10 to 10 by an optical transmission line 31 are inputted from an input terminal 40, and their intensities of light are amplified by an optical amplifier 23a. A proper wavelength required for information communication is selected and outputted and is inputted to optical modulators 221 to 223 . Modulation signals of electric signals are inputted to optical modulators 221 to 223 , and output light of an optical demultiplexer 41 is modulated by these electric signals. Outputs of optical modulators 221 to 223 are mixed and multiplexed by an optical multiplexer 24 and are amplified to the optical level required for the device by an optical amplifier 23b, and the modulated optical signal is outputted from an output terminal 402 .

Description

Detailed Description of the Invention

[0001]

The present invention is used in optical wavelength division multiplexing communication. The present invention is used in optical communication networks. The present invention relates to a technique for simplifying an optical circuit of a communication node which constitutes an optical communication network.

[0002]

2. Description of the Related Art Conventionally, an optical wavelength division multiplexing transmission network for multiplexing and transmitting a plurality of light wavelengths has been widely known. This conventional example will be described with reference to FIGS.
FIG. 7 is a block diagram of an optical communication network. Figure 8
It is a block configuration diagram of an electro-optical conversion unit. FIG. 9 is a block configuration diagram of the photoelectric conversion unit. In FIG. 7, the optical communication network includes communication nodes 10 ₁ to 10 ₆ and an optical transmission line 11 as a communication line. The communication nodes 10 ₁ to 10 ₆ are generally composed of a receiving device, a cross-connect device, a transmitting device, etc.
It has an electro-optical conversion unit or an opto-electric conversion unit.

As shown in FIG. 8, the electro-optical converting section includes a light source 2 for generating a plurality of optical carrier waves 43 ₁ to 43 ₃ having different wavelengths.
1 ₁ to 21 _3, different wavelengths of the optical carriers 43 ₁ to 43 ₃ modulated by respective different electrical signals the optical modulator 22
_{1 to} 22 ₃ , an optical multiplexer 24 that multiplexes and wavelength-multiplexes the output optical signals of the optical modulators 22 _{1 to} 22 ₃ , and an optical amplifier 23 that amplifies the wavelength-multiplexed optical signal to a required level To be done.

As shown in FIG. 9, the opto-electric converter converts the wavelength-multiplexed optical signal arriving at the input terminal 30 ₁ into the optical demultiplexer 2.
The optical signals are demultiplexed by 5, and the demultiplexed optical signals are input to the opto-electric conversion devices 26 _{1 to} 26 ₃ and converted into electric signals. This electric signal is discriminators 27 _{1 to} 27 ₃
Are decoded into data and output from the output terminals 30 ₂ to 30 ₄ .

[0005]

In the configuration of this conventional example, when information is transmitted from a certain communication node to another communication node using a plurality of wavelengths, each communication node is provided with a light source, and each communication node is provided with a light source. Stabilize the wavelength of each light source of
It is necessary to adjust the wavelength to a specified wavelength or to change the center wavelength of the optical demultiplexer on the receiving side of each communication node according to each communication node on the transmitting side.

The present invention has been made in view of such a background, and an object thereof is to provide an optical wavelength division multiplexing system capable of simplifying the configuration of the optical circuit of each communication node and the optical adjustment procedure. And An object of the present invention is to provide an optical wavelength multiplex communication system capable of reducing the manufacturing cost of a communication node. An object of the present invention is to provide an optical wavelength multiplex communication system that can reduce the cost of network construction.

[0007]

SUMMARY OF THE INVENTION The present invention is an optical wavelength division multiplexing communication system, which is characterized by generating a plurality of communication nodes belonging to one network for performing wavelength division multiplexing communication and generating optical carriers of a plurality of wavelengths. A single carrier generation node and an optical transmission line that distributes the optical carrier to the plurality of communication nodes, and the communication node has a selection unit that selects an optical carrier that arrives at the optical transmission line. And an optical modulator for modulating light having the same wavelength as the optical carrier.

In the present invention, the commonly used optical carrier is directly
It is characterized in that it is distributed to each communication node, and its idea is different from that of distributing only the synchronization signal and other information to each communication node. As a result, when each communication node sends information, it is not necessary to individually stabilize the wavelength of the light source of its own communication node, and it is not necessary to adjust to the specified wavelength, and the center wavelength of the optical demultiplexer on the receiving side is set to the transmitting side. Since it is not necessary to change each communication node and the configuration of the optical circuit and the optical adjustment procedure of each communication node can be simplified, the device design of the communication node can be facilitated, the device cost can be reduced, and the network can be constructed. The cost can be reduced.

It is preferable that the optical modulator includes an optical modulator that receives the selected optical carrier.

The optical modulation means comprises a wavelength-synchronized light source that outputs light having a wavelength equal to that of the selected optical carrier, and an optical modulator that receives and modulates output light from the wavelength-synchronized light source. You can also do it. As a result, since the optical carrier can be regenerated, even if distortion occurs in the optical transmission line, it can be removed.

The wavelength locked light source is preferably an injection locked laser diode.

Further, the modulating means may be an injection-locked laser diode which is directly modulated.

It is desirable that the carrier generation node comprises a plurality of light sources for respectively generating optical carriers used in the network, and an optical multiplexer for multiplexing optical carriers obtained at the outputs of the plurality of light sources. .

It is preferable that one carrier generation node is provided in the network, and the plurality of light sources are provided corresponding to all optical carrier wavelengths used in the network.

It is preferable that the optical transmission line is an optical transmission line that connects the carrier generation node and the plurality of communication nodes in a star shape.

Alternatively, it is preferable that the optical transmission line is provided in at least a part of a communication line connecting the communication nodes to each other.

At this time, the communication path may include a ring-shaped communication path, and the optical transmission path may be provided side by side with the ring-shaped communication path.

The communication node includes a relay means for relaying an optical carrier wave arriving at the input side of the optical transmission path to an output side, and a means for branching the optical carrier wave used by the communication node from the relay means. Can also be

[0019]

The carrier generation node generates an optical carrier used by a plurality of communication nodes in the network. A plurality of wavelengths used by each communication node are multiplexed on this optical carrier. This optical carrier is distributed to each communication node for communication.
This allows each communication node to individually adjust the center wavelength of the optical demultiplexer to the communication node on the transmission side without generating an optical carrier and adjusting the wavelength to a specified wavelength. Therefore, the configuration of the optical circuit and the optical adjustment procedure can be simplified.

The optical carrier wave distributed to each communication node is demultiplexed by selecting the wavelength used in the communication node. The demultiplexed optical carrier is modulated by the modulation signal and output.

For this modulation, an optical modulator for directly inputting and modulating the selected optical carrier may be used, or a light source for generating a reproduction light synchronized with the wavelength of the selected optical carrier is provided. Alternatively, an optical modulator that receives and modulates the output light of the light source may be used. By using the light source that generates the reproduction light, it is possible to obtain the reproduced optical carrier by removing the distortion generated by the optical transmission line and the like.

An injection-locked laser diode may be used as the wavelength-locked light source, or the wavelength-locked light source and the optical modulator may be realized by one directly-modulated injection-locked radar diode.

The carrier generation node generates an optical carrier used in the network by using a plurality of light sources. The optical carriers obtained at the outputs of the plurality of light sources are multiplexed by an optical multiplexer and distributed in the network. As a result, expensive optical components can be centralized in one place, and the cost for network construction can be reduced.

As a method of distributing an optical carrier wave to each communication node, the carrier wave generation node and each communication node may be connected in a star shape, or each communication node may be provided with an optical transmission path as a communication path used for communication. It is also possible to provide another optical transmission line in parallel with and to connect the carrier generation node to this.

[0025]

【Example】

[First Embodiment] The configuration of a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of the first embodiment of the present invention. FIG. 2 is a block configuration diagram of the electro-optical conversion unit included in the communication node. FIG. 3 is a block diagram of a carrier generation node.

The present invention is an optical wavelength multiplex communication system, and is characterized by communication nodes 10 ₁ to 10 ₆ belonging to one network and performing wavelength multiplex communication, and an optical carrier 4 of a plurality of wavelengths.
One carrier generation node 30 for generating 3 ₁ to 43 ₃
And the optical carriers 43 ₁ to 43 ₃ are connected to the communication nodes 10 ₁ to
10 ₆ and an optical transmission line 31 for distribution to the communication node 1
0 ₁ 10 _6, as shown in FIG. 2, the optical transmission line 3
1, the optical demultiplexer 41 as a selection means for selecting the optical carrier waves 43 ₁ to 43 ₃ that arrive at 1 and the selected optical carrier wave 43 ₁
There is to provided with an optical modulator 22 ₁ to 22 ₃ as a modulation means for modulating a to 43 ₃ equal wavelength.

As shown in FIG. 3, the carrier generation node 30
Is provided in the network, and the light sources 21 _{1 to} 21 ₃ are provided corresponding to the wavelengths of all the optical carriers 43 ₁ to 43 ₃ used in the network. In the first embodiment of the present invention, the optical transmission line 31 includes the carrier generation node 30 and the communication node 10.
₁ to 10 ₆ are connected in a star shape.

The electro-optical converter included in the communication nodes 10 ₁ to 10 ₆ will be described in more detail with reference to FIG. The electro-optical converter includes an optical demultiplexer 41, optical modulators 22 _{1 to} 22 ₃ ,
It is composed of an optical multiplexer 24 and optical amplifiers 23a and 23b.

The optical transmission line 31 allows the communication nodes 10 ₁ ...
The optical carriers 43 ₁ to 43 ₃ transmitted to 10 ₆ are input from the input terminal 40 ₁ and their optical intensities are amplified by the optical amplifier 23a. The optical demultiplexer 41 selects and outputs an appropriate wavelength required for information communication, and the optical modulators 22 ₁ to
22 ₃ is input. Modulation signals based on electric signals are input to the optical modulators 22 _{1 to} 22 _3, and the output lights of the optical demultiplexer 41 are modulated by the electric signals. The outputs of the optical modulators 22 _{1 to} 22 ₃ are mixed and multiplexed by the optical multiplexer 24, further amplified by the optical amplifier 23 b to the optical level required for the device, and the modulated optical signal is output from the output terminal 40 ₂ .

The carrier generation node 30 will be described in more detail with reference to FIG. Each of the light sources 21 _{1 to} 21 ₃ oscillates at a plurality of different reference wavelengths required for information transmission of the network. These are mixed and multiplexed by the optical multiplexer 24, and then amplified by the optical amplifier 23 to the optical level required for communication, and the optical carriers 43 ₁ to 43 _{3 are} transmitted.
Is transmitted to the transmission line 31 for transmitting the.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is an overall configuration diagram of the second embodiment of the present invention. FIG. 5 is a block diagram of the communication nodes 10 ₁ to 10 ₆ used in the second embodiment of the present invention. The second embodiment of the present invention is a configuration example in which a carrier generation node 30 and nodes 10 ₁ to 10 ₆ are connected in a ring shape as shown in FIG. An electro-optical conversion unit included in the nodes 10 ₁ to 10 _{6 according} to the second embodiment of the present invention will be described with reference to FIG. Optical carrier 43 _{1-43 3} input from the input terminal 70 ₁ is amplified by the optical amplifier 23a,
It is transmitted to the adjacent node via the output terminal 70 ₃ .
Optical carrier waves 43 ₁ to 43 ₃ output from the optical amplifier 23a
Is branched and the light intensity is further amplified by the optical amplifier 23b. The optical demultiplexer 41 selectively outputs an appropriate wavelength required for information communication, and the optical modulators 22 ₁ to
22 ₃ is input. Modulation signals based on electric signals are input to the optical modulators 22 _{1 to} 22 _3, and the output lights of the optical demultiplexer 41 are modulated by the electric signals. The outputs of the optical modulators 22 _{1 to} 22 ₃ are mixed and multiplexed by the optical multiplexer 24, further amplified by the optical amplifier 23c to the optical level required for the device, and the modulated optical signal is output from the output terminal 70 ₂ .

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a block diagram of the communication nodes 10 ₁ to 10 ₆ used in the third embodiment of the present invention. The third embodiment of the present invention is an optical demultiplexer 41 and an optical modulator 22 _1.
To 22 ₃ where the wavelength tuning light source 42 ₁ to 42 ₃ is interposed between the differs from the first or second embodiment the present invention. The wavelength-synchronized light sources 42 _{1 to} 42 ₃ are optical carriers 43 ₁ to 4 3.
It is an injection-locked laser diode having a property that the output wavelength of the light source is pulled to the wavelength of 3 ₃ .

The optical transmission line 31 allows the communication nodes 10 ₁ ...
The optical carriers 43 ₁ to 43 ₃ transmitted to 10 ₆ are input from the input terminal 40 ₁ and their optical intensities are amplified by the optical amplifier 23a. An appropriate wavelength required for information communication is selectively output by the optical demultiplexer 41, and the wavelength synchronization light source 42
It is input to a _{1-42 3.} As described above, the wavelength-synchronized light sources 42 _{1 to} 42 ₃ are injection-locked laser diodes having a property that the output wavelength of the light source is pulled into the wavelengths of the optical carriers 43 ₁ to 43 ₃ , so that the optical transmission line 31 Even if the optical carrier waves 43 ₁ to 43 ₃ include distortion in the process of propagation, the optical carrier waves 4 ₁ to 4 _{3 are} caused by the wavelength locked light sources 42 _{1 to} 42 _3.
3 ₁ to 4 _{3 3} are reproduced without distortion. The output lights of the wavelength synchronization light sources 42 _{1 to} 42 ₃ are output from the optical modulators 22 ₁ to 22 ₁ .
22 ₃ respectively. Optical modulators 22 _{1 to} 22 ₃
A modulation signal based on an electric signal is input to the optical modulator, and the output light of the optical demultiplexer 41 is modulated by the electric signal.
The outputs of the optical modulators 22 _{1 to} 22 ₃ are mixed and multiplexed by the optical multiplexer 24, further amplified by the optical amplifier 23 b to the optical level required for the device, and the modulated optical signal is output from the output terminal 40 ₂ .

According to the first to third embodiments of the present invention, the wavelength of the signal used for information communication is uniquely determined by the optical carrier wave transmitted by the carrier wave generation node 30 in all the communication nodes 10 ₁ to 10 ₆ . Therefore, it is not necessary to stabilize individually the wavelengths of light sources of each of the communication nodes 10 ₁ to 10 _6, the communication node on the transmitting side the center wavelength of the optical demultiplexer 41 of each communication node 10 ₁ to 10 ₆ recipient of Since it is not necessary to change it for each communication node, the communication nodes 10 ₁ to 10
₆ Device design becomes easy and device cost can be reduced. Therefore, the cost required for network construction can be reduced.

[0035]

As described above, according to the present invention,
The configuration of the optical circuit of each communication node and the optical adjustment procedure can be simplified. As a result, the device design of the communication node can be facilitated, the device cost can be reduced, and the cost required for network construction can be reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of an electro-optical conversion unit included in a communication node.

FIG. 3 is a block diagram of a carrier generation node.

FIG. 4 is an overall configuration diagram of a second embodiment of the present invention.

FIG. 5 is a block configuration diagram of a communication node used in the second embodiment of the present invention.

FIG. 6 is a block configuration diagram of a communication node used in the third embodiment of the present invention.

FIG. 7 is a block diagram of an optical communication network.

FIG. 8 is a block configuration diagram of an electro-optical conversion unit.

FIG. 9 is a block configuration diagram of a photoelectric conversion unit.

[Explanation of symbols]

10 ₁ to 10 ₆ Communication node 11, 31 Optical transmission line 21 _{1 to} 21 ₃ Light source 22 _{1 to} 22 ₃ Optical modulator 23, 23 a, 23 b Optical amplifier 24 Optical multiplexer 25, 41 Optical demultiplexer 26 _{1 to} 26 ₃ Opto-electric conversion device 27 _{1 to} 27 ₃ discriminator 30 carrier generation node 30 ₁ , 40 ₁ , 70 ₁ input terminal 30 ₂ to 30 ₄ , 40 ₂ , 50, 70 ₂ , 70 ₃ output terminal 42 _{1 to} 42 ₃ wavelength synchronization Light source 43 ₁ to 43 ₃ Optical carrier

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Claims (11)

[Claims] 1. A plurality of communication nodes that belong to one network and perform wavelength division multiplexing communication, one carrier generation node that generates optical carriers of a plurality of wavelengths, and optical transmission that distributes the optical carriers to the plurality of communication nodes. And a selecting means for selecting an optical carrier coming to this optical transmission path, and an optical modulating means for modulating light having a wavelength equal to that of the selected optical carrier. Optical wavelength multiplexing communication system. 2. The optical wavelength division multiplex communication system according to claim 1, wherein the optical modulator includes an optical modulator that receives the selected optical carrier. 3. The optical modulation means comprises a wavelength-synchronized light source that outputs light having a wavelength equal to that of the selected optical carrier, and an optical modulator that inputs and modulates output light from the wavelength-synchronized light source. The optical wavelength division multiplexing communication system according to claim 1. 4. The optical wavelength division multiplexing system according to claim 3, wherein the wavelength-locked light source is an injection-locked laser diode. 5. The optical wavelength division multiplexing communication system according to claim 1, wherein the optical modulator is an injection-locked laser diode that is directly modulated. 6. The carrier generation node comprises a plurality of light sources for respectively generating optical carriers used in the network, and an optical multiplexer for multiplexing optical carriers obtained at outputs of the plurality of light sources. The optical wavelength division multiplexing communication system according to claim 1. 7. The optical wavelength according to claim 6, wherein one carrier generation node is provided in the network, and the plurality of light sources are provided corresponding to all optical carrier wavelengths used in the network. Multiplex communication system. 8. The optical WDM communication according to claim 1, wherein the optical transmission line is an optical transmission line connecting the carrier generation node and the plurality of communication nodes in a star shape. method. 9. The optical wavelength division multiplexing communication system according to claim 1, wherein the optical transmission line is provided side by side with at least a part of a communication line connecting the communication nodes to each other. 10. The optical wavelength division multiplexing communication system according to claim 9, wherein said communication path includes a ring-shaped communication path, and said optical transmission path is provided side by side with this ring-shaped communication path. 11. The communication node comprises a relay means for relaying an optical carrier coming to an input side of the optical transmission line to an output side, and a means for branching an optical carrier used by the communication node from the relay means. The optical wavelength division multiplexing communication system according to claim 9, which includes.