Patent Grant
7236703
The present invention relates to an optical wavelength division multiplexing and transmission apparatus adapted for a wavelength division multiplexing and transmission system in which a plurality of optical wavelength signals having wavelengths different from each other are multiplexed and transmitted.
Next, an operation will be described below.
In a wavelength division multiplexing and transmission system (hereinafter, called WDM transmission system), a large number of types of information are respectively assigned to a plurality of optical wavelength signals having wavelengths different from each other to convert the types of information into the optical wavelength signals. In the transmitter end rack 101, the converted optical wavelength signals λ1, λ2, λ3, . . . and λn are taken out from the optical wavelength multiplexer 111 as a multiplexed signal. This multiplexed signal is amplified in the amplifier 112 and is sent out to the optical transmission line 113. In the receiver end rack 102, the multiplexed signal transmitted through the optical transmission line 113 is amplified in the amplifier 114 and is demultiplexed to the optical wavelength signals λ1, λ2, λ3, . . . and λn having wavelengths different from each other in the optical wavelength demultiplexer 115. The optical wavelength signals λ1, λ2, λ3, . . . and λn taken out from the optical wavelength demultiplexer 115 are demodulated in a latter stage to a plurality of electric signals denoting the types of original information.
Because the conventional optical wavelength division multiplexing and transmission apparatus has the above-described configuration, it is not easy to expand a multiplex function so as to increase the number of optical wavelength signals. A plurality of wavelengths of a plurality of optical wavelength signals multiplexed in an optical wavelength multiplexer are set to be placed at wavelength intervals so as not to interfere with each other. Therefore, in cases where the number of optical wavelength signals multiplexed with each other is increased due to the increase of a quantity of information to be transmitted, wavelengths assigned to pieces of information and possible to be processed in both an optical wavelength multiplexer and an optical wavelength demultiplexer run short. In this case, it is required to replace both the optical wavelength multiplexer and the optical wavelength demultiplexer with both another optical wavelength multiplexer and another optical wavelength demultiplexer in which additional optical wavelength signals can be received and processed. However, because both the optical wavelength multiplexer and the optical wavelength demultiplexer set in operation are taken out from the conventional optical wavelength division multiplexing and transmission apparatus, the communication is interrupted during the replacement. Therefore, a problem has arisen that it is not easy to actually perform the replacement.
The present invention is provided to solve the above-described problem, and the object of the present invention is to provide an optical wavelength division multiplexing and transmission apparatus in which both an optical wavelength multiplexer and an optical wavelength demultiplexer for an early operation are installed at an processing capacity corresponding to a prescribed number of optical wavelength signals to suppress an initial cost and a plurality of groups of other optical wavelength multiplexers and other optical wavelength demultiplexers suitable for the demand of communication are additionally installed one after another while maintaining a communication condition.
An optical wavelength division multiplexing and transmission apparatus according to the present invention comprises a master rack and at least a slave rack possible to be combined with and coupled to the master rack. A structure body of the master rack accommodates a first optical wavelength multiplexer, in which a plurality of prescribed optical wavelength signals of a group are multiplexed with each other and a first multiplexed signal is output, and a synthetic optical wavelength multiplexer in which the first multiplexed signal output from the first optical wavelength multiplexer and a second multiplexed signal are multiplexed with each other and a synthetic multiplexed signal is output. A structure body of the slave rack accommodates a second optical wavelength multiplexer in which a plurality of optical wavelength signals of a group having a wavelength distribution different from that of the group of prescribed optical wavelength signals multiplexed by the first optical wavelength multiplexer are multiplexed with each other and are output as the second multiplexed signal.
Therefore, in the WDM transmission system, in cases where the number of optical wavelength signals multiplexed is small in the early operation and it is expected that the number of optical wavelength signals multiplexed is increased in the future, the optical wavelength signals are divided in advance into a plurality of groups, and the slave rack is additionally installed for each group without stopping the system installed for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
An optical wavelength division multiplexing and transmission apparatus according to the present invention comprises a master rack and at least a slave rack possible to be combined with and coupled to the master rack. A structure body of the master rack accommodates a synthetic optical wavelength demultiplexer in which a synthetic multiplexed signal formed by multiplexing a plurality of multiplexed signals, which are respectively formed of a plurality of groups of optical wavelength signals having a plurality of optical wavelength distributions different from each other, with each other is received, the synthetic multiplexed signal is demultiplexed to both a first multiplexed signal and a second multiplexed signal and both the first multiplexed signal and the second multiplexed signal are output, and a first optical wavelength demultiplexer in which the first multiplexed signal output by the synthetic optical wavelength demultiplexer is demultiplexed to a plurality of optical wavelength signals of one group and the group of optical wavelength signals is output. A structure body of the slave rack accommodates a second optical wavelength demultiplexer in which the second multiplexed signal output by the synthetic optical wavelength demultiplexer is demultiplexed to a plurality of optical wavelength signals of another group and the group of optical wavelength signals is output.
Therefore, a plurality of slave racks can be additionally installed one after another on a receiver end without stopping the system installed for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
An optical wavelength division multiplexing and transmission apparatus according to the present invention comprises a master rack and at least a slave rack possible to be combined with and coupled to the master rack. A structure body of the master rack accommodates a first optical wavelength multiplexer in which a plurality of prescribed optical wavelength signals of a group are multiplexed with each other and a first multiplexed signal is output, a synthetic optical wavelength multiplexer in which the first multiplexed signal output from the first optical wavelength multiplexer and a second multiplexed signal are multiplexed with each other and a first synthetic multiplexed signal is output, a synthetic optical wavelength demultiplexer in which a second synthetic optical wavelength transmitted from another optical wavelength division multiplexing and transmission apparatus of an opposite end through an optical transmission line is demultiplexed to both a third multiplexed signal and a fourth multiplexed signal and both the third multiplexed signal and the fourth multiplexed signal are output, and a first optical wavelength demultiplexer in which the third multiplexed signal output from synthetic optical wavelength demultiplexer is demultiplexed to a plurality of optical wavelength signals of a group and the group of optical wavelength signals is output. A structure body of the slave rack accommodates a second optical wavelength multiplexer in which a plurality of optical wavelength signals of a group having a wavelength distribution different from that of the group of prescribed optical wavelength signals multiplexed by the first optical wavelength multiplexer are multiplexed with each other and are output as the second multiplexed signal, and a second optical wavelength demultiplexer in which the fourth multiplexed signal output by the synthetic optical wavelength demultiplexer is demultiplexed to a plurality of optical wavelength signals of another group and the group of optical wavelength signals is output.
Therefore, because each of the master rack and the slave rack has both a function of multiplying the optical wavelength signals and a function of demultiplying the multiplexed signal, the functions can be simultaneously added in the additional installation. Also, a plurality of slave racks can be additionally installed one after another on a receiver end without stopping the system installed for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
On a transmitter end, an optical wavelength division multiplexing and transmission apparatus according to the present invention further comprises a plurality of noise cut filters corresponding to the first multiplexed signal and the second multiplexed signal respectively on an input side of the synthetic optical wavelength multiplexer on which the first multiplexed signal and the second multiplexed signal are input.
Therefore, because only effective wavelength components are taken out from the multiplexed signals and are transmitted, the transmission quality of the multiplexed signals can be improved. Also, a plurality of slave racks can be additionally installed one after another on the transmitter end without stopping the system installed for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
On a transceiver side, an optical wavelength division multiplexing and transmission apparatus according to the present invention further comprises a plurality of noise cut filters corresponding to the first multiplexed signal and the second multiplexed signal respectively on an input side of the synthetic optical wavelength multiplexer on which the first multiplexed signal and the second multiplexed signal are input.
Therefore, only effective wavelength components can be taken out of the multiplexed signals in the transmission operation and can be transmitted. Also, because each rack has both the transmission function and the reception function, the functions can be simultaneously added in the additional installation, and a plurality of slave racks can be additionally installed one after another without stopping the system installed for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
On a transmitter end, an optical wavelength division multiplexing and transmission apparatus according to the present invention further comprises a plurality of dispersion compensation fibers corresponding to the first multiplexed signal and the second multiplexed signal respectively on an input side of the synthetic optical wavelength multiplexer on which the first multiplexed signal and the second multiplexed signal are input.
Therefore, the distortion of effective wavelength components of the multiplexed signals given by an optical fiber of the transmission line can be compensated, and the transmission quality of the multiplexed signals can be heightened. Also, a plurality of slave racks can be additionally installed one after another in the transmitter without stopping the system for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
On a transceiver side, an optical wavelength division multiplexing and transmission apparatus according to the present invention further comprises a plurality of dispersion compensation fibers corresponding to the first multiplexed signal and the second multiplexed signal respectively on an input side of the synthetic optical wavelength multiplexer on which the first multiplexed signal and the second multiplexed signal are input.
Therefore, the distortion of effective wavelength components of the multiplexed signals given by an optical fiber of a transmission line can be compensated, and the transmission quality of the multiplexed signals can be heightened. Also, because each rack has both the transmission function and the reception function, the functions can be simultaneously added in the additional installation, and a plurality of slave racks can be additionally installed one after another without stopping the system installed for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
An optical wavelength division multiplexing and transmission apparatus according to the present invention further comprises an amplifier of the master rack for the first multiplexed signal, an amplifier of the master rack for the synthetic multiplexed signal, a wavelength level monitoring device of the master rack for monitoring an output of the amplifier for the synthetic multiplexed signal, an amplifier of the slave rack for the second multiplexed signal, and a plurality of output control circuits for selectively controlling a plurality of levels of signals output from the amplifier for the first multiplexed signal, the amplifier for the second multiplexed signal and the amplifier for the synthetic multiplexed signal respectively in response to a detection output of the wavelength level monitoring device in which a plurality of levels of the optical wavelength signals of the first multiplexed signal, the second multiplexed signal and the synthetic multiplexed signal are monitored.
Therefore, level differences among the multiplexed signals of the groups of the optical wavelength signals can be corrected before the signal transmission, and the transmission qualities of the multiplexed signals can be equally maintained. Also, as the transmitter, a plurality of slave racks can be additionally installed one after another without stopping the system installed for the early operation in the additional installation. Accordingly, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
Hereinafter, the best mode for carrying out the present invention will now be described with reference to the accompanying drawings to explain the present invention in more detail.
A block diagram of the configuration of a transmission side of an optical wavelength division multiplexing and transmission apparatus is shown in
A structure body of the master rack 20 accommodates an optical wavelength multiplexer (or first optical wavelength multiplexer) 21, an amplifier 22, an amplifier 24 and a synthetic optical wavelength multiplexer 23 integrally placed with each other. Also, a structure body of the slave rack 30 accommodates an optical wavelength multiplexer (or second optical wavelength multiplexer) 31 and an amplifier 32 integrally placed with each other. The slave rack 30 is coupled to the master rack 20, and an optical output of the slave rack 30 is input to the synthetic optical wavelength multiplexer 23 through an optical connector 25. In the same manner, the same type of slave rack as that of the slave rack 30 can be connected to an optical connector 26. Here, the master rack 20 has an interface so as to prevent the influence occurring in the additional installation of another slave rack 30.
In the master rack 20, a plurality of optical wavelength signals λ1, λ2, . . . and λn of one group formed in a prescribed optical wavelength distribution are input and multiplexed in the optical wavelength multiplexer 21. Thereafter, a multiplexed signal (or first multiplexed signal) output from the optical wavelength multiplexer 21 is amplified to a prescribed level in the amplifier 22 and is input to the synthetic optical wavelength multiplexer 23. In cases where the slave rack 30 is not connected to the master rack 20, the multiplexed signal input to the synthetic optical wavelength multiplexer 23 is output from the synthetic optical wavelength multiplexer 23 as a synthetic multiplexed signal without processing the multiplexed signal and is transmitted to a receiver of the opposite end through both the amplifier 24 and an optical transmission line 113. As is described above, in cases where the number of optical wavelength signals to be transmitted is small in the early stage in which the WDM transmission system is structured, only the master rack 20 is installed and operated.
In cases where the increase of the number of optical wavelength signals to be transmitted is required due to the increase of a quantity of information, the multiplex and transmission capability of only the master rack 20 currently set in operation is not sufficient. In this case, the slave rack 30 is coupled to the master rack 20. In this coupling operation, though the amplifier 32 is connected to the synthetic optical wavelength multiplexer 23 through the optical connector 25, the transmission function of the master rack 20 currently operated is not stopped. A group of a plurality of optical wavelength signals λn+1, λn+2, . . . and λm, which are input to the optical wavelength multiplexer 31 and are multiplexed, is formed to have a wavelength distribution different from that of the group of optical wavelength signals λ1, λ2, . . . and λn. A multiplexed signal (or second multiplexed signal) output from the optical wavelength multiplexer 31 is amplified in the amplifier 32 and is fed to the synthetic optical wavelength multiplexer 23 of the master rack 20. Thereafter, the multiplexed signal is multiplexed with other multiplexed signals and is transmitted to the receiver of the opposite end as a synthetic multiplexed signal.
As is described above, in the first embodiment, the slave rack 30 can be easily and additionally installed in the optical wavelength division multiplexing and transmission apparatus without stopping the operation of the system installed for the early operation system. Accordingly, in the WDM transmission system, in cases where the number of optical wavelength signals multiplexed with each other is small in the early operation and it is expected that the number of optical wavelength signals multiplexed with each other is increased in the future, the optical wavelength signals increased in the future are divided in advance into a plurality of groups, and the slave rack 30 can be additionally installed for each group. Therefore, the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
A block diagram of the configuration of a reception side of an optical wavelength division multiplexing and transmission apparatus is shown in
Next, an operation will be described below.
A synthetic multiplexed signal, which is transmitted from an opposite end transmitter having the configuration shown in
As is described above, in the second embodiment, the receiver end of the optical wavelength division multiplexing and transmission apparatus has the configuration in which the slave rack 50 can be additionally installed. Accordingly, the slave rack 50 can be easily and additionally installed in the optical wavelength division multiplexing and transmission apparatus without stopping the operation of the system installed for the early operation, and the optical wavelength division multiplexing and transmission apparatus can be widely used for various purposes.
A block diagram of the configuration of an optical wavelength division multiplexing and transmission apparatus, in which circuits of a transmission function and circuits of a reception function are integrally formed, is shown in
120 indicates an optical transmission line through which a synthetic multiplexed signal (or first synthetic multiplexed signal) of the synthetic optical wavelength multiplexer 23 is transmitted to a receiver of the opposite end. 140 indicates an optical transmission line through which a synthetic multiplexed signal (or first synthetic multiplexed signal) of a transmitter of the opposite end is transmitted. A master rack 200 indicates a receiving and transmitting system installed for the early operation. A slave rack 300 is coupled to the master rack 200 in cases where the number of optical wavelength signals processed is increased, and a transmitting and receiving function is expanded by the slave rack 300. Here, because a wavelength distribution of a group of optical wavelength signals denoting an input of the optical wavelength multiplexer (or first optical wavelength multiplexer) 21 is the same that denoting an output of optical wavelength demultiplexer (or first optical wavelength demultiplexer) 44, the optical wavelength signals denoting the input of the optical wavelength multiplexer 21 are indicated by the same reference numerals λ1, λ2, . . . and λn as those denoting the output of optical wavelength demultiplexer 44. In the same manner, in the slave rack 300, a plurality of optical wavelength signals denoting the input are indicated by the same reference numerals λn+1, λn+2, . . . and λm as those denoting the output.
In the master rack 200, a plurality of optical wavelength signals λ1, λ2, . . . and λn are multiplexed in the optical wavelength multiplexer 21, and a multiplexed signal (or first multiplexed signal) is output from the optical wavelength multiplexer 21. This multiplexed signal is amplified in the amplifier 22 and is fed to the synthetic optical wavelength multiplexer 23. In the synthetic optical wavelength multiplexer 23, the multiplexed signal is multiplexed with the same type of multiplexed signal (or second multiplexed signal) as that of the multiplexed signal to obtain a synthetic multiplexed signal (or first synthetic multiplexed signal), and the synthetic multiplexed signal is output to the optical transmission line 120 through the amplifier 24. In the synthetic optical wavelength demultiplexer 42, after a synthetic multiplexed signal (or second synthetic multiplexed signal), which is transmitted from another optical wavelength division multiplexing and transmission apparatus of the opposite end through the optical transmission line 140, is amplified in the amplifier 41, the synthetic multiplexed signal is input and demultiplexed to a plurality of multiplexed signals. One multiplexed signal (or third multiplexed signal) demultiplexed in the synthetic optical wavelength demultiplexer 42 is amplified in the amplifier 43. Thereafter, the multiplexed signal is input to the optical wavelength demultiplexer (or first optical wavelength demultiplexer) 44 and is demultiplexed to the optical wavelength signals λ1, λ2, . . . and λn of one group.
Also, in cases where the slave rack 300 is coupled to the master rack 200, a plurality of optical wavelength signals λn+1, λn+2, . . . and λm having a wavelength distribution different from that of the optical wavelength signals λ1, λ2, . . . and λn are multiplexed with each other in the optical wavelength multiplexer (or second optical wavelength multiplexer) 31, and a multiplexed signal (or second multiplexed signal) is fed to the synthetic optical wavelength multiplexer 23 of the master rack 200 through the amplifier 32. Also, another multiplexed signal, which is formed by demultiplexing the synthetic multiplexed signal transmitted through the optical transmission line 140 in the synthetic optical wavelength demultiplexer 42, is demultiplexed to the optical wavelength signals λn+1, λn+2, . . . and λm in the optical wavelength demultiplexer (or second optical wavelength demultiplexer) 52, and the optical wavelength signals λn+1, λn+2, . . . and λm is output.
As is described above, in the third embodiment, when the slave rack 300 is additionally installed in the optical wavelength division multiplexing and transmission apparatus, the slave rack 300 can be easily and additionally installed without stopping the operation of the system installed for the early operation. Also, because each of the master rack 200 and the slave rack 300 accommodates circuits of an optical multiplexing function and circuits of an optical demultiplexing function, the circuits of the optical multiplexing function and the circuits of the optical demultiplexing function in the slave rack 300 can be simultaneously and additionally installed in the optical wavelength division multiplexing and transmission apparatus, and workability can be further improved in the optical wavelength division multiplexing and transmission apparatus.
A block diagram of the configuration of an optical wavelength division multiplexing and transmission apparatus, in which an additional circuit is installed on the transmitter end, is shown in
When the group of optical wavelength signals λ1, λ2, . . . and λn multiplexed in the first optical wavelength multiplexer 21 is multiplexed in the synthetic optical wavelength multiplexer 23 with the group of optical wavelength signals λn+1, λn+2, . . . and λm multiplexed in the optical wavelength multiplexer 31, noise components included in the groups of optical wavelength signals are added to each other so as to increase a noise level, and an S/N ratio of the synthetic multiplexed signal is lowered. To prevent the lowering of the S/N ratio, a band of a prescribed band width is set for each group of optical wavelength signals, and unnecessary signal components existing outside the band are cut away in each of the noise cut filters 201, 202 and 203. In
As is described above, in the fourth embodiment, the noise cut filters 201, 202 and 203 are inserted into the optical wavelength division multiplexing and transmission apparatus so as to transmit only an effective wavelength portion of each group of optical wavelength signals through the corresponding noise cut filter. Therefore, communication quality of the optical wavelength division multiplexing and transmission apparatus can be improved.
A block diagram of the configuration of an optical wavelength division multiplexing and transmission apparatus, in which a plurality of dispersion compensation fibers 205, 206 and 207 are installed on the receiver end as an additional circuit, is shown in
When each optical wavelength signal is transmitted through an optical fiber of a transmission line, a wavelength distortion occurs in the optical wavelength signal due to the dispersion of the optical wavelength signal peculiar to the optical fiber. Therefore, the transmission quality of the optical wavelength signal is lowered. To prevent the lowering of the transmission quality, each multiplexed signal is fed to the synthetic optical wavelength multiplexer 23 through the corresponding dispersion compensation fiber 205, 206 or 207 so as to compensate for the dispersion of the multiplexed signal expected to be accumulated in an optical fiber of a transmission line. Each of the dispersion compensation fibers 205, 206 and 207 has a function of preventing the dispersion of the multiplexed signal occurring in an optical fiber of a transmission line, and the distortion of each optical wavelength signal can be prevented. Here, in the same manner as the installation of the noise cut filters 202 and 203, it is applicable that the dispersion compensation fibers 206 and 207 be installed in the slave racks 30 respectively. Also, the installation of the dispersion compensation fibers 205, 206 and 207 can be adapted for the optical wavelength division multiplexing and transmission apparatus of
As is described above, the dispersion compensation fibers 205, 206 and 207 are inserted into the optical wavelength division multiplexing and transmission apparatus, and the communication quality of the WDM transmission system can be improved.
A block diagram of the configuration of an optical wavelength division multiplexing and transmission apparatus, in which a wavelength level monitoring device 208 and a plurality of output control circuits 209, 210 and 211 are installed on the receiver end as an additional circuit, is shown in
In the master rack 20, the wavelength level monitoring device 208 has a function of monitoring levels of the optical wavelength signals of the synthetic multiplexed signal which is output from the amplifier 24. A monitored level of each optical wavelength signal detected in the wavelength level monitoring device 208 is fed back to the corresponding amplifier 22 or 32 through the corresponding output control circuit 209 or 210 installed in the master rack 20 or the slave rack 30, and the output control circuits 209 and 210 control the amplifiers 22 and 32 respectively to equalize levels of the optical wavelength signals of the multiplexed signals (or first and second multiplexed signals) with each other. Also, the output control circuit 211 controls the amplifier 24 to set a level of the synthetic multiplexed signal output from the amplifier 24 of the final stage to a predetermined value.
As is described above, in the sixth embodiment, level differences among the multiplexed signals of the groups of optical wavelength signals can be corrected before the signal transmission, and the transmission qualities of the multiplexed signals can be equally maintained.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP00/05151 | 7/31/2000 | WO | 00 | 3/28/2002 |
| Publishing Document | Publishing Date | Country | Kind |
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| WO02/11337 | 2/7/2002 | WO | A |
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