JP2007142736A - Optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission system which secures reliability in a distributor while avoiding a large increase of a system cost. <P>SOLUTION: A signal light λ<SB>1</SB>outputted from a first optical transmitter 11 is optically amplified in an optical amplifier A<SB>1</SB>after passing through a transmission-side switch 14, a first optical line 21, a distribution-side switch 31, and an input-side optical bypass circuit 32, and is outputted from an output terminal P<SB>1</SB>after passing through an output-side optical bypass circuit 33. When an optical amplifier A<SB>3</SB>becomes faulty, a signal light λ<SB>2</SB>outputted from a second optical transmitter 12 is optically amplified in the optical amplifier A<SB>1</SB>after passing through the transmission-side switch 14, a second optical line 22, the distribution-side switch 31, and the input-side optical bypass circuit 32; and is outputted from an output terminal P<SB>3</SB>after passing through the output-side optical bypass circuit 33. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical transmission system for transmitting information such as video as signal light from a transmission unit of a base station to a reception unit of a subscriber's house.

  2. Description of the Related Art Conventionally, an optical transmission system that distributes information such as video as signal light from a base station to a subscriber's home has a configuration shown in FIG. FIG. 6 is a configuration diagram of a conventional optical transmission system 2. The optical transmission system 2 shown in this figure includes a transmission unit 40 provided in a base station, a relay unit 50 that transmits signal light output from the transmission unit 40, and a large number of signal lights transmitted by the relay unit 50. And a distribution unit 60 for distributing to the subscriber's home.

The transmission unit 40 includes a first optical transmitter 41, a second optical transmitter 42, and a transmission side switching unit 44. The relay unit 50 includes a first optical line 51 and a second optical line 52. The first optical line 51 includes optical amplifiers 511 and 513 and optical fiber transmission lines 512 and 514. The second optical line 52 includes optical amplifiers 521 and 523 and optical fiber transmission lines 522 and 524. Further, the distribution unit 60 includes a dispensing side switching unit 61, optical splitter 62 and optical amplifiers _A 1 to A _4.

  The transmission side switching unit 44 included in the transmission unit 40 selectively selects an optical connection between the first optical transmitter 41 and the second optical transmitter 42 and the first optical line 51 and the second optical line 52. Switch. The distribution side switching unit 61 included in the distribution unit 60 selectively switches the optical connection between the first optical line 51 and the second optical line 52 and the optical branching unit 62.

In the transmission unit 40, the first optical transmitter 41 and the first optical line 51 are optically connected to each other by the transmission side switching unit 44, and in the distribution unit 60, the first optical line 51 and the optical branching unit are arranged by the distribution side switching unit 61. 62 is optically connected to each other, the signal light output from the first optical transmitter 41 passes through the transmission side switching unit 44, the first optical line 51, and the distribution side switching unit 61, and the optical branching unit 62. The optical branching unit 62 multi-branches and optical amplifiers A _{1 to} A ₄ optically amplify and then transmit to a large number of subscriber homes.

If the first optical transmitter 41 fails, the second optical transmitter 42 and the first optical line 51 are optically connected to each other by the transmission-side switching unit 44 in the transmission unit 40, and the second optical transmitter. signal light output from the 42 transmitting side switching unit 44, via the first optical line 51 and dispensing side switching unit 61 reaches the optical splitter 62, the multi-branched by the optical amplifiers a ₁ ~ this optical splitter 62 after being optically amplified by a _4, sent to multiple subscriber's home.

If the first optical line 51 fails, the transmission unit 40 optically connects the first optical transmitter 41 and the second optical line 52 to each other in the transmission unit 40, and the distribution unit 60 distributes them. The second optical line 52 and the optical branching device 62 are optically connected to each other by the side switching unit 61, and the signal light output from the first optical transmitter 41 is transmitted to the transmission side switching unit 44 and the second optical line 52. and through the distribution side switching unit 61 reaches the optical splitter 62 after being optically amplified by the optical amplifier a ₁ to a ₄ is a multi-branched by the optical splitter 62, is transmitted to a number of subscriber premises.

As described above, in the conventional optical transmission system 2, each of the transmission unit 40 and the relay unit 50 has a redundant configuration, and even when some failure occurs in the transmission unit 40 or the relay unit 50, it is possible to return to the subscriber's home. Signal light can be transmitted.
JP-A-11-215150

As described above, the conventional optical transmission system typically has a redundant configuration for the transmission unit and the relay unit, but typically does not have a redundant configuration for the distribution unit. For example, if the optical amplifier A ₁ fails, a situation in which signal light is not transmitted to the subscriber's home downstream of the optical amplifier A ₁ occurs. If the distribution unit has a redundant configuration, it is necessary to provide a large number of optical switches for path switching and spare optical amplifiers, resulting in a very high system cost.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical transmission system capable of ensuring the reliability of a distribution unit while avoiding a significant increase in system cost. To do.

An optical transmission system according to the present invention includes (1) a first optical transmitter that outputs signal light of a first wavelength, a second optical transmitter that outputs signal light of a second wavelength different from the first wavelength, A transmission unit including a transmission side switching unit that selectively switches an optical connection between the first optical transmitter and the second optical transmitter and the first output terminal and the second output terminal; and (2) a transmission unit A relay unit including a first optical line that transmits the signal light output from the first output end of the first optical line and a second optical line that transmits the signal light output from the second output end of the transmission unit; And a distribution unit that optically amplifies the signal light transmitted through the first optical line or the second optical line and outputs the amplified light from M output terminals P _{1 to} P _M. However, M is an integer of 2 or more.

Further, the optical distribution unit included in the optical transmission system according to the present invention includes (a) M optical amplifiers A _{1 to} A _M for optically amplifying the input signal light and outputting it, and (b) a first optical line. A distribution-side switching unit that selectively switches an optical connection between the second optical line and the M optical amplifiers A _{1 to} A _M; and (c) a distribution-side switching unit and the M optical amplifiers A _1. It is provided between the to a _M, the first optical amplifier _{a m1} and the second optical amplifier _{a m @ 2} of the M optical amplifiers _a 1 to a _M, from the distribution side switching unit to the first optical amplifier _{a m1} toward the signal light of the first wavelength is input to the first optical amplifier a _m1, to enter the signal light of the first wavelength traveling from the distribution side switching unit to the second optical amplifier a _{m @ 2} to the second optical amplifier a _{m @ 2,} the distribution side the signal light of the second wavelength traveling from the switching unit to the first optical amplifier a _m1 is input to the second optical amplifier a _{m @ 2,} the distribution side switching An input side optical bypass circuit from parts to input signal light of the second wavelength toward the second optical amplifier A _{m @ 2} to the first optical amplifier A _m1, (d) M pieces of optical amplifiers A ₁ to A _M and M The signal light having the first wavelength, which is provided between the output terminals P _{1 to} P _M and optically amplified by the first optical amplifier A _m1, is output from the output terminal P _m1 and is optically amplified by the second optical amplifier A _m2. The first wavelength signal light is output from the output terminal P _m2 , the second wavelength signal light optically amplified by the first optical amplifier A _m1 is output from the output terminal P _m2 , and the light is output by the second optical amplifier A _m2. And an output-side optical bypass circuit that outputs the amplified signal light of the second wavelength from the output terminal P _m1 .

Each of the M optical amplifiers A _{1 to} A _M performs output constant control so that the level of the signal light that is optically amplified and output becomes the target output level, and the input signal light level increases beyond a predetermined threshold value. In this case, it is preferable to increase the target output level when an output change instruction is received from a centrally managed center.

  Each of the input-side optical bypass circuit and the output-side optical bypass circuit includes: (a) a first demultiplexer and a second demultiplexer that demultiplex and output the first and second wavelength signal lights respectively input; (B) The first wavelength signal light demultiplexed and output by the first demultiplexer and the second wavelength signal light demultiplexed and output by the second demultiplexer are multiplexed. (C) a second wavelength signal light output after being demultiplexed by the first demultiplexer, and a first wavelength demultiplexed by the second demultiplexer and output. And a second multiplexer that combines and outputs the signal light.

  The distribution side switching unit includes (a) a first optical branching device that splits the signal light transmitted by the first optical line into two branches, and (b) a second light that splits the signal light transmitted through the second optical path into two branches. Select one of a branching device and (c) one signal light branched and output by the first optical branching device and one signal light branched and output by the second optical branching device. One of the first optical switch to output, (d) the other signal light branched and output by the first optical branching device, and the other signal light branched and output by the second optical branching device A second optical switch that selectively outputs the light, (e) a third optical branching device that branches the signal light output from the first optical switch, and (f) a signal light output from the second optical switch. And a fourth optical branching device.

  The distribution side switching unit includes (a) a first optical branching device that branches the signal light transmitted through the first optical line into M branches, and (b) a second light that splits the signal light transmitted through the second optical lines into M branches. One of a branching device, (c) any signal light output after being branched by M by the first optical branching device, and any signal light output by being branched by M by the second optical branching device And M optical switches that selectively output.

  In the second optical transmitter, the wavelength of the output signal light is preferably variable within a wavelength range including the first wavelength and the second wavelength.

  The transmission unit further includes a third optical transmitter that outputs signal light of the first wavelength, and the transmission side switching unit includes the first optical transmitter, the second optical transmitter, the third optical transmitter, and the first output terminal. It is preferable to selectively switch the optical connection between the second output terminal and the second output terminal.

  According to the present invention, it is possible to ensure the reliability of the distribution unit while avoiding a significant increase in system cost.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a configuration diagram of an optical transmission system 1 according to the present embodiment. The optical transmission system 1 shown in this figure includes a transmission unit 10, a relay unit 20, and a distribution unit 30.

The transmission unit 10 includes a first optical transmitter 11, a second optical transmitter 12, and a transmission side switching unit 14. The first optical transmitter 11 outputs the first wavelength lambda ₁ of the signal light. The second optical transmitter 12 outputs signal light having a second wavelength λ ₂ different from the first wavelength λ _1, and the wavelength of the output signal light may be fixed to the second wavelength λ ₂ . It is preferable that the wavelength of the output signal light is variable within a wavelength range including the first wavelength λ ₁ and the second wavelength λ ₂ . The transmission side switching unit 14 selectively switches the optical connection between the first optical transmitter 11 and the second optical transmitter 12 and the first optical line 21 and the second optical line 22.

  The relay unit 20 includes a first optical line 21 and a second optical line 22. Each of the first optical line 21 and the second optical line 22 transmits the signal light output from the transmission unit 10 to the distribution unit 30. The first optical line 21 includes optical amplifiers 211 and 213 and optical fiber transmission lines 212 and 214, and transmits the signal light through the optical fiber transmission lines 212 and 214 while optically amplifying the signal light with the optical amplifiers 211 and 213. The second optical line 22 includes optical amplifiers 221 and 223 and optical fiber transmission lines 222 and 224, and transmits the signal light through the optical fiber transmission lines 222 and 224 while optically amplifying the signal light with the optical amplifiers 221 and 223.

The distribution unit 30 optically amplifies the signal light transmitted through the first optical line 21 or the second optical line 22 and outputs the amplified signal light from the output terminals P _{1 to} P ₄ . Distributor 30 includes distribution side switching unit 31, input optical bypass circuit 32, the output side optical bypass circuit 33, and an optical amplifier _A 1 to A _4.

Each of the optical amplifiers A _{1 to} A ₄ optically amplifies the input signal light and outputs it. Each of the optical amplifiers A _{1 to} A ₄ performs output constant control so that the level of the signal light that is amplified and output becomes the target output level, and the input signal light level increases above a predetermined threshold value. It is preferable to increase the target output level when receiving an output change instruction.

The distribution side switching unit 31 selectively switches the optical connection between the first optical line 21 and the second optical line 22 and the optical amplifiers A _{1 to} A ₄ . The input side optical bypass circuit 32 is provided between the distribution side switching unit 31 and the optical amplifiers A _{1 to} A ₄ . The output side optical bypass circuit 33 is provided between the optical amplifiers A _{1 to} A ₄ and the output terminals P _{1 to} P ₄ .

Input optical bypass circuit 32 causes the input signal light lambda ₁ directed from the distribution side switching unit 31 to the optical amplifier A ₁ to the optical amplifier A _1, a signal light lambda ₁ directed from the distribution side switching unit 31 to the optical amplifier A ₂ is inputted to the optical amplifier a _2, an optical signal lambda ₂ directed from the distribution side switching unit 31 to the optical amplifier a ₁ is input to the optical amplifier a _3, a signal light lambda ₂ directed from the distribution side switching unit 31 to the optical amplifier a ₂ is input to the optical amplifier _{a 4.} Further, the input-side optical bypass circuit 32, the signal light lambda ₁ directed from the distribution side switching unit 31 to the optical amplifier A ₃ is input to the optical amplifier A _3, from the distribution side switching unit 31 the optical amplifier A signal light directed to ₄ lambda ₁ is input to the optical amplifier A ₄ , the signal light λ ₂ directed from the distribution side switching unit 31 to the optical amplifier A ₃ is input to the optical amplifier A ₁ , and the signal light λ directed from the distribution side switching unit 31 to the optical amplifier A ₄ . and inputs ₂ to the optical amplifier _{a 2.}

Output optical bypass circuit 33, to output the signal light lambda ₁ which is optically amplified by the optical amplifier A ₁ from the output terminal P _1, an output signal light lambda ₁ which is optically amplified by the optical amplifier A ₂ from the output terminal P ₂ It is allowed, to output the light amplified signal light lambda ₂ from the output terminal P ₃ by the optical amplifier a _1, to output the signal light lambda ₂ which is optically amplified by the optical amplifier a ₂ from the output end P _4. Further, the output-side optical bypass circuit 33, the optical amplifier A ₃ by to output the signal light lambda ₁ that has been optically amplified from the output end P _3, the optical amplifier A output terminal P ₄ a signal light lambda ₁ which is optically amplified by ₄ It is outputted from, to output the light amplified signal light lambda ₂ from the output terminal P ₄ by the optical amplifier a _3, and outputs the signal light lambda ₂ which is optically amplified by the optical amplifier a ₄ from the output end P _2.

Preferably, each of the optical amplifier 211, the optical amplifier 213, the optical amplifier 211, the optical amplifier 213, and the optical amplifiers A _{1 to} A ₄ uses an optical fiber in which an Er element is added to the optical waveguide region as an optical amplification medium. Optical fiber amplifier. In this case, for example, the first wavelength λ ₁ is 1560 nm and the second wavelength λ ₂ is 1550 nm. Each of these optical amplifiers, the first optical transmitter 11, the second optical transmitter 12, the transmission side switching unit 14, and the distribution side switching unit 31 has a network function, and is centrally managed at the center via the network ( Status confirmation and control).

  FIG. 2 is a configuration diagram of the input-side optical bypass circuit 32 included in the optical transmission system 1 according to the present embodiment. The input side optical bypass circuit 32 shown in this figure includes optical demultiplexers 121 to 124 and optical multiplexers 131 to 134 between input terminals 101 to 104 and output terminals 111 to 114.

Each of the input terminals 101 to 104 of the input side optical bypass circuit 32 is connected to the output terminal of the distribution side switching unit 31. The output end 111 is connected to the input end of the optical amplifier A _1, the output terminal 112 is connected to the input end of the optical amplifier A _2, an output terminal 113 is connected to the input end of the optical amplifier A _3, the output terminal 114 is light It is connected to an input terminal of the amplifier a _4.

The optical demultiplexer 121 demultiplexes the signal light input to the input terminal 101, outputs the signal light λ ₁ to the optical multiplexer 131, and outputs the signal light λ ₂ to the optical multiplexer 133. The optical demultiplexer 123 demultiplexes the signal light input to the input terminal 103, outputs the signal light λ ₁ to the optical multiplexer 133, and outputs the signal light λ ₂ to the optical multiplexer 131.

The optical multiplexer 131 receives the signal light λ ₁ output from the optical demultiplexer 121 and also receives the signal light λ ₂ output from the optical demultiplexer 123 to multiplex these signal lights. And output from the output end 111. The optical multiplexer 133 receives the signal light λ ₁ output from the optical demultiplexer 123 and also receives the signal light λ ₂ output from the optical demultiplexer 121 to multiplex these signal lights. And output from the output end 113.

The optical demultiplexer 122 demultiplexes the signal light input to the input terminal 102, outputs the signal light λ ₁ to the optical multiplexer 132, and outputs the signal light λ ₂ to the optical multiplexer 134. The optical demultiplexer 124 demultiplexes the signal light input to the input terminal 104, outputs the signal light λ ₁ to the optical multiplexer 134, and outputs the signal light λ ₂ to the optical multiplexer 132.

The optical multiplexer 132 receives the signal light λ ₁ output from the optical demultiplexer 122 and also receives the signal light λ ₂ output from the optical demultiplexer 124 to multiplex these signal lights. And output from the output terminal 112. The optical multiplexer 134 receives the signal light λ ₁ output from the optical demultiplexer 124 and also receives the signal light λ ₂ output from the optical demultiplexer 122 to multiplex these signal lights. And output from the output end 114.

That is, the input-side optical device circuit 32 inputs the signal light λ ₁ to the input terminal 101, outputs it from the output terminal 111, inputs it to the input terminal 102, outputs it from the output terminal 112, and outputs it to the input terminal 103. The data is input and output from the output terminal 113, input to the input terminal 104, and output from the output terminal 114. The input side optical device circuit 32 inputs the signal light λ ₂ to the input terminal 101, outputs it from the output terminal 113, inputs it to the input terminal 102, outputs it from the output terminal 114, and inputs it to the input terminal 103. Output from the output terminal 111, input to the input terminal 104, and output from the output terminal 112.

The output side optical bypass circuit 33 has the same configuration as the input side optical bypass circuit 32. However, the input terminal 101 of the output side optical bypass circuit 33 is connected to the output end of the optical amplifier A _1, the input terminal 102 is connected to the output end of the optical amplifier A _2, an input terminal 103 is an output terminal of the optical amplifier A ₃ The input terminal 104 is connected to the output terminal of the optical amplifier A ₄ , the output terminal 111 is connected to the output terminal P ₁ , the output terminal 112 is connected to the output terminal P ₂ , and the output terminal 113 is connected to the output terminal P 1. is connected to _3, the output terminal 114 thereof is connected to the output terminal P _4.

  FIG. 3 is a configuration diagram of the distribution-side switching unit 31 included in the optical transmission system 1 according to the present embodiment. The distribution side switching unit 31 shown in this figure includes an optical branching unit 221, an optical branching unit 222, an optical switch 231, an optical switch 232, and an optical branching between the input terminal 201 and the input terminal 202 and the output terminals 211 to 214. And optical branching device 242.

  The input end 201 is connected to the first optical line 21, and the input end 202 is connected to the second optical line 22. The output terminal 211 is connected to the input terminal 101 of the input side optical bypass circuit 32, the output terminal 212 is connected to the input terminal 102 of the input side optical bypass circuit 32, and the output terminal 213 is the input terminal 103 of the input side optical bypass circuit 32. The output terminal 214 is connected to the input terminal 104 of the input side optical bypass circuit 32.

  The optical splitter 221 splits the signal light transmitted through the first optical line 21 and input to the input terminal 201 into two branches, and outputs the branched signal light to the optical switch 231 and the optical switch 232. The optical branching device 222 splits the signal light transmitted through the second optical line 22 and input to the input terminal 202 into two branches, and outputs the branched signal light to the optical switch 231 and the optical switch 232.

  The optical switch 231 selectively outputs either the signal light output from the optical branching unit 221 and the signal light output from the optical branching unit 222 to the optical branching unit 241. The optical switch 232 selectively outputs to the optical branch 242 either the signal light that is output from the optical branching unit 221 and the signal light that is output from the optical branching unit 222 or reaches.

  The optical branching device 241 branches the signal light output from the optical switch 231 into two, and outputs the branched signal light to the output terminal 211 and the output terminal 212. The optical splitter 242 splits the signal light output from the optical switch 232 into two, and outputs the branched signal light to the output terminal 213 and the output terminal 214.

  That is, the distribution side switching unit 31 sends the signal light input to either the input end 201 or the input end 202 from the output end 211 and the output end 212 to the input side optical bypass circuit 32 according to the state of the optical switch 231. Depending on the state of the optical switch 232, the signal light input to either the input terminal 201 or the input terminal 202 is output from the output terminal 213 and the output terminal 214 to the input-side optical bypass circuit 32.

Next, an example of the operation of the optical transmission system 1 according to the present embodiment will be described. In the normal state, the first optical transmitter 11 and the first optical line 21 are optically connected to each other by the transmission side switching unit 14 in the transmission unit 10, and the first optical line is distributed by the distribution side switching unit 31 in the distribution unit 30. 21 and the input terminals 101 to 104 of the input side optical bypass circuit 32 are optically connected to each other. At this time, the signal light λ ₁ output from the first optical transmitter 11 reaches the input-side optical bypass circuit 32 via the transmission-side switching unit 14, the first optical line 21, and the distribution-side switching unit 31.

The signal light λ ₁ input to the input end 101 of the input side optical bypass circuit 32 is output from the output end 111 of the input side optical bypass circuit 32, is optically amplified by the optical amplifier A ₁ , and is output to the output side optical bypass circuit 33. via the input terminal 101 and output terminal 111 of, is output from the output terminal P _1, is sent to a large number of subscriber premises. The signal light λ ₁ input to the input end 102 of the input side optical bypass circuit 32 is output from the output end 112 of the input side optical bypass circuit 32, optically amplified by the optical amplifier A ₂ , and input to the output side optical bypass circuit 33. through the end 102 and output end 112, is output from the output terminal P _2, are transmitted to multiple subscriber's home.

The signal light λ ₁ input to the input end 103 of the input side optical bypass circuit 32 is output from the output end 113 of the input side optical bypass circuit 32, optically amplified by the optical amplifier A ₃ , and input to the output side optical bypass circuit 33. through the end 103 and output end 113, is output from the output terminal P _3, is transmitted to a number of subscriber premises. The signal light λ ₁ input to the input end 104 of the input side optical bypass circuit 32 is output from the output end 114 of the input side optical bypass circuit 32, optically amplified by the optical amplifier A ₄ , and input to the output side optical bypass circuit 33. through the end 104 and output end 114, is output from the output terminal P _4, is transmitted to a number of subscriber premises.

If the first optical line 21 fails, the first optical transmitter 11 and the second optical line 22 are optically connected to each other by the transmission side switching unit 14 in the transmission unit 10, and the distribution side in the distribution unit 30. The second optical line 22 and the input ends 101 to 104 of the input side optical bypass circuit 32 are optically connected to each other by the switching unit 31. The signal light λ ₁ output from the first optical transmitter 11 reaches the input-side optical bypass circuit 32 via the transmission-side switching unit 14, the second optical line 22, and the distribution-side switching unit 31. The subsequent processing is the same as that in the normal state.

  Further, if the first optical transmitter 11 fails, the second optical transmitter 12 and the first optical line 21 are optically connected to each other by the transmission side switching unit 14 in the transmission unit 10. The signal light output from the second optical transmitter 12 reaches the input side optical bypass circuit 32 via the transmission side switching unit 14, the first optical line 21 and the distribution side switching unit 31.

If the signal light output from the second optical transmitter 12 has a wavelength λ ₁ , the signal light λ ₁ input to the input-side optical bypass circuit 32 is optically amplified through a path similar to that in the normal state and many To the subscriber's home. On the other hand, if the signal light output from the second optical transmitter 12 has a wavelength λ ₂ , the signal light λ ₂ input to the input-side optical bypass circuit 32 is optically amplified through a path as described below and many To the subscriber's home.

That is, the signal light λ ₂ input to the input end 101 of the input side optical bypass circuit 32 is output from the output end 113 of the input side optical bypass circuit 32, is optically amplified by the optical amplifier A ₃ , and is output to the output side optical bypass circuit 33. via the input terminal 103 and output terminal 111 of, is output from the output terminal P _1, is sent to a large number of subscriber premises. The signal light λ ₂ input to the input end 102 of the input side optical bypass circuit 32 is output from the output end 114 of the input side optical bypass circuit 32, optically amplified by the optical amplifier A ₄ , and input to the output side optical bypass circuit 33. through the end 104 and output end 112, is output from the output terminal P _2, are transmitted to multiple subscriber's home.

The signal light λ ₂ input to the input end 103 of the input side optical bypass circuit 32 is output from the output end 111 of the input side optical bypass circuit 32, optically amplified by the optical amplifier A ₁ , and input to the output side optical bypass circuit 33. through the end 101 and output end 113, is output from the output terminal P _3, is transmitted to a number of subscriber premises. The signal light λ ₂ input to the input end 104 of the input side optical bypass circuit 32 is output from the output end 112 of the input side optical bypass circuit 32, optically amplified by the optical amplifier A ₂ , and input to the output side optical bypass circuit 33. through the end 102 and output end 114, is output from the output terminal P _4, is transmitted to a number of subscriber premises.

Further, if when the optical amplifier A ₃ fails, the transmitting-side switching unit 14 in the transmitting unit 10, a first optical transmitter 11 and the first optical line 21 are optically connected to each other, the second light transmission The device 12 and the second optical line 22 are optically connected to each other. The signal light λ ₁ is output from the first optical transmitter 11, and the signal light λ ₂ is output from the second optical transmitter 12. Further, in the distribution unit 30, the distribution side switching unit 31 optically connects the first optical line 21 and the input ends 101 and 102 of the input side optical bypass circuit 32, and the second optical line 22 and the input side optical bypass. The input terminals 103 and 104 of the circuit 32 are optically connected to each other.

Note that a series of line switching accompanying the failure of the optical amplifier A ₃ is performed by the centralized management center detecting the failure information of the optical amplifier via the network, and the center instructing each device to switch the line based on the information. A method is preferable in which distribution is performed and each device performs line switching in accordance with the same instruction.

At this time, the signal light λ ₁ output from the first optical transmitter 11 passes through the transmission side switching unit 14, the first optical line 21, and the distribution side switching unit 31, and the input terminal 101 and the input of the input side optical bypass circuit 32. End 102 is reached. The signal light λ ₁ input to the input end 101 of the input side optical bypass circuit 32 is output from the output end 111 of the input side optical bypass circuit 32, is optically amplified by the optical amplifier A ₁ , and is output to the output side optical bypass circuit 33. via the input terminal 101 and output terminal 111 of, is output from the output terminal P _1, is sent to a large number of subscriber premises. The signal light λ ₁ input to the input end 102 of the input side optical bypass circuit 32 is output from the output end 112 of the input side optical bypass circuit 32, is optically amplified by the optical amplifier A ₂ , and is output to the output side optical bypass circuit 33. Are output from the output terminal P ₂ via the input terminal 102 and the output terminal 112, and transmitted to a large number of subscribers' homes.

On the other hand, the signal light λ ₂ output from the second optical transmitter 12 passes through the transmission side switching unit 14, the second optical line 22, and the distribution side switching unit 31, and the input end 103 and the input end of the input side optical bypass circuit 32. 104 is reached. The signal light λ ₂ input to the input end 103 of the input side optical bypass circuit 32 is output from the output end 111 of the input side optical bypass circuit 32, is optically amplified by the optical amplifier A ₁ , and is output to the output side optical bypass circuit 33. via the input terminal 101 and output terminal 113 of, is output from the output terminal P _3, is transmitted to a number of subscriber premises. The signal light λ ₂ input to the input end 104 of the input side optical bypass circuit 32 is output from the output end 112 of the input side optical bypass circuit 32, is optically amplified by the optical amplifier A ₂ , and is output to the output side optical bypass circuit 33. via the input terminal 102 and output terminal 114 of, is output from the output terminal P _4, is transmitted to a number of subscriber premises.

Thus, when the optical amplifier A ₃ fails, the signal light λ ₂ output from the second optical transmitter 12 does not pass through the failed optical amplifier A ₃ , and normal optical amplifiers A ₁ , A ₂ is optically amplified and output from the output terminals P ₃ and P _{4 of the} distribution unit 30 to the subscriber's home. Therefore, the optical transmission system 1 can ensure the reliability of the distribution unit 30 while avoiding a significant increase in system cost by adding a few optical components in the distribution unit 30.

Note that, when the optical amplifier A ₃ fails, the level of the signal light input to the optical amplifiers A ₁ and A ₂ is doubled as compared with the normal state described above. The optical amplifiers A ₁ and A ₂ perform constant output control so that the level of the signal light amplified and output becomes the target output level. However, when the input signal light level increases, the target output level remains unchanged. there the output terminal _{P 1, P 2, P 3} , each of the output signal light level reaching the _{P 4} is lowered. Therefore, it is preferable that the optical amplifiers A ₁ and A ₂ increase the target output level when the input signal light level increases beyond a predetermined threshold value. In addition, since the increase in the target output level is an event that should be linked to the line switching in the event of failure, a means that is implemented in response to an instruction from the center (output change accompanying line switching) is also conceivable.

In the above configuration, when the optical amplifier A ₃ fails, not only the failed optical amplifier A ₃ is used, but also the normal optical amplifier A ₄ is not used. Signal light is affected. Therefore, the distribution-side switching unit 31 included in the optical transmission system 1 according to the present embodiment preferably has the configuration shown in FIG. 4 instead of the configuration shown in FIG.

  FIG. 4 is another configuration diagram of the distribution-side switching unit 31 included in the optical transmission system 1 according to the present embodiment. The distribution side switching unit 31 shown in this figure includes an optical branching unit 251, an optical branching unit 252, and optical switches 261 to 264 between the input terminal 201 and the input terminal 202 and the output terminals 211 to 214.

  The optical splitter 251 splits the signal light transmitted through the first optical line 21 and input to the input terminal 201 into four branches, and outputs the four-branched signal lights to the optical switches 261 to 264. The optical splitter 252 splits the signal light transmitted through the second optical line 22 and input to the input terminal 202 into four branches, and outputs the four-branched signal lights to the optical switches 261 to 264.

  The optical switch 261 outputs any one of the signal light branched and output by the optical branching device 251 and any one of the signal light branched and output by the optical branching device 252 to the output terminal 211. To do. The optical switch 262 outputs any one of the signal lights branched and output by the optical branching unit 251 and any one of the signal lights branched and output by the optical branching unit 252 to the output terminal 212. To do.

  The optical switch 263 outputs any one of the signal light branched and output by the optical branching unit 251 and any one of the signal light branched and output by the optical branching unit 252 to the output terminal 213. To do. The optical switch 264 outputs any one of the signal light branched and output by the optical branching unit 251 and any one of the signal light branched and output by the optical branching unit 252 to the output terminal 214. To do.

  That is, the distribution side switching unit 31 outputs the signal light input to either the input terminal 201 or the input terminal 202 to the output terminal 211 according to the state of the optical switch 261, and according to the state of the optical switch 262. The signal light input to either the input terminal 201 or the input terminal 202 is output to the output terminal 212, and the signal light input to either the input terminal 201 or the input terminal 202 is output according to the state of the optical switch 263. The signal light output to the terminal 213 is output to the output terminal 214 according to the state of the optical switch 264, and the signal light input to either the input terminal 201 or the input terminal 202 is output.

When the distribution side switching unit 31 having the configuration shown in FIG. 4 is used, in the normal state, the first optical transmitter 11 and the first optical line 21 are optically connected to each other by the transmission side switching unit 14 in the transmission unit 10. In the distribution unit 30, the distribution side switching unit 31 optically connects the first optical line 21 and the input terminals 101 to 104 of the input side optical bypass circuit 32 to each other. The signal light λ ₁ output from the first optical transmitter 11 passes through the transmission side switching unit 14, the first optical line 21, the distribution side switching unit 31, and the input side optical bypass circuit 32, and then the optical amplifiers A ₁ to A ₁ . The light is amplified by A ₄ and output from the output terminals P _{1 to} P ₄ via the output side optical bypass circuit 33.

If the optical amplifier A ₃ fails, the first optical transmitter 11 and the first optical line 21 are optically connected to each other by the transmission side switching unit 14 in the transmission unit 10, and the second optical transmitter 12. And the second optical line 22 are optically connected to each other. The signal light λ ₁ is output from the first optical transmitter 11, and the signal light λ ₂ is output from the second optical transmitter 12. In the distribution unit 30, the distribution side switching unit 31 optically connects the first optical line 21 and the input ends 101, 102, and 104 of the input side optical bypass circuit 32 to each other. The input terminal 103 of the optical bypass circuit 32 is optically connected to each other.

The signal light λ ₁ output from the first optical transmitter 11 is output from the output terminals P ₁ , P ₂ , and P ₄ through the same path as in the normal state. On the other hand, the signal light λ ₂ output from the second optical transmitter 12 reaches the input terminal 103 of the input side optical bypass circuit 32 via the transmission side switching unit 14, the second optical line 22 and the distribution side switching unit 31. The signal light λ ₂ input to the input end 103 of the input side optical bypass circuit 32 is output from the output end 111 of the input side optical bypass circuit 32, is optically amplified by the optical amplifier A ₁ , and is output to the output side optical bypass circuit 33. via the input terminal 101 and output terminal 113 of, is output from the output terminal P _3, is transmitted to a number of subscriber premises.

Thus, when the optical amplifier A ₃ fails, the signal light λ ₂ output from the second optical transmitter 12 does not pass through the failed optical amplifier A ₃ and is transmitted from the normal optical amplifier A _1. is amplified and outputted from the output terminal P ₃ of the dispensing unit 30 to the subscriber's home. Therefore, the optical transmission system 1 can ensure the reliability of the distribution unit 30 while avoiding a significant increase in system cost by adding a few optical components in the distribution unit 30.

In addition, when the distribution side switching unit 31 having the configuration shown in FIG. 3 is used, the signal light transmitted to all the subscriber homes is affected, whereas the distribution side switching having the configuration shown in FIG. When the unit 31 is used, only the signal light transmitted to the subscriber's home connected to the failed optical amplifier A ₃ and the optical amplifier A ₁ paired therewith is affected, and the other optical amplifiers A ₂ , signal light sent to the subscriber's home leading to a ₄ each is not affected.

  In the distribution side switching unit 31 having the configuration shown in FIG. 4, the required number of switches increases in proportion to the number of optical amplifiers included in the distribution unit 30. However, compared with the case where the distribution unit is configured redundantly by providing a switch at the input / output end of the optical amplifier, the distribution side switching unit 31 having the configuration shown in FIG. An optical amplifier is also unnecessary.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, depending on the required reliability and quality, the transmission unit 10 preferably has the configuration shown in FIG. FIG. 5 is another configuration diagram of the transmission unit 10 included in the optical transmission system 1 according to the present embodiment. The transmitter 10 shown in FIG. 5 includes a first optical transmitter 11, a second optical transmitter 12, a third optical transmitter 13, and a transmission side switching unit 14. The first optical transmitter 11 outputs the first wavelength lambda ₁ of the signal light. The second optical transmitter 12 outputs signal light having a second wavelength λ ₂ different from the first wavelength λ ₁ . The third optical transmitter 13 outputs the first wavelength lambda ₁ of the signal light. The transmission side switching unit 14 selectively selects an optical connection between the first optical transmitter 11, the second optical transmitter 12, and the third optical transmitter 13 and the first optical line 21 and the second optical line 22. Switch to.

Further, the distribution unit 30, the input optical bypass circuit 32, the output side optical bypass circuit 33 and optical amplifiers A ₁ to A ₄ is suitable in the range of integral Considering the points of accommodation and cost, Separate type is also acceptable. In the latter case, when a failure occurs in any one of the optical amplifiers A _{1 to} A ₄ , the failure occurs while the signal light is bypassed by the input side optical bypass circuit 32 and the output side optical bypass circuit 33. It is possible to replace the optical amplifier.

1 is a configuration diagram of an optical transmission system 1 according to the present embodiment. It is a block diagram of the input side optical bypass circuit 32 contained in the optical transmission system 1 which concerns on this embodiment. It is a block diagram of the distribution side switching part 31 contained in the optical transmission system 1 which concerns on this embodiment. It is another block diagram of the distribution side switching part 31 contained in the optical transmission system 1 which concerns on this embodiment. It is another block diagram of the transmission part 10 contained in the optical transmission system 1 which concerns on this embodiment. It is a block diagram of the conventional optical transmission system 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical transmission system, 10 ... Transmission part, 11 ... 1st optical transmitter, 12 ... 2nd optical transmitter, 13 ... 3rd optical transmitter, 14 ... Transmission side switching part, 20 ... Relay part, 21 ... 1st 1 optical line, 22 ... second optical line, 30 ... distributor, 31 ... distributor side switching unit, 32 ... input optical bypass circuit, 33 ... output optical bypass _{circuit, A} 1 to A M _... optical amplifier.

Claims (7)

A first optical transmitter that outputs signal light of a first wavelength; a second optical transmitter that outputs signal light of a second wavelength different from the first wavelength; the first optical transmitter and the second optical transmitter; A transmission-side switching unit that selectively switches an optical connection between the first output terminal and the second output terminal;
A first optical line that transmits the signal light output from the first output end of the transmission unit; and a second optical line that transmits the signal light output from the second output end of the transmission unit. A relay section;
A distribution unit that optically amplifies signal light transmitted through the first optical line or the second optical line and outputs the amplified signal light from M output terminals P _{1 to} P _M ;
With
The light distribution unit is
M optical amplifiers A _{1 to} A _M for optically amplifying the input signal light and outputting it,
A distribution-side switching unit that selectively switches an optical connection between the _first optical line and the second optical line and the M optical amplifiers A _{1 to} A _M ;
A first optical amplifier A _m1 and a second optical amplifier A of the _M optical amplifiers A _{1 to} A _M , which are provided between the distribution side switching unit and the M optical amplifiers A _{1 to} A _M. for _m2, the signal light of the first wavelength traveling from the distribution side switching unit to the first optical amplifier a _m1 is input to the first optical amplifier a _m1, the direction from the distribution side switching unit to the second optical amplifier a _{m @ 2} 1 The signal light having the wavelength is input to the second optical amplifier A _m2, and the signal light having the second wavelength directed from the distribution side switching unit to the first optical amplifier A _m1 is input to the second optical amplifier A _m2 , and the distribution side switching is performed. An input-side optical bypass circuit for inputting the signal light having the second wavelength from the unit to the second optical amplifier _Am2 , to the first optical amplifier _Am1 ,
Provided between the _M optical amplifiers A _{1 to} A _M and the M output terminals P _{1 to} P _M , the first wavelength signal light amplified by the first optical amplifier A _m1 is output to the output terminal. The first wavelength signal light output from the P _m1 and optically amplified by the second optical amplifier A _m2 is output from the output terminal P _m2, and the second wavelength signal light optically amplified by the first optical amplifier A _{m1 is} output. An output-side optical bypass circuit that outputs from the output terminal P _m1 the signal light of the second wavelength that is output from the output terminal P _m2 and optically amplified by the second optical amplifier A _m2 ;
including,
An optical transmission system (where M is an integer of 2 or more). Each of the _M optical amplifiers A _{1 to} A _M performs output constant control so that the level of the signal light that is optically amplified and outputted becomes the target output level, and the input signal light level exceeds a predetermined threshold value. 2. The optical transmission system according to claim 1, wherein the target output level is increased when increased or when an output change instruction is received. Each of the input side optical bypass circuit and the output side optical bypass circuit,
A first demultiplexer and a second demultiplexer for demultiplexing and outputting signal light of the first wavelength and the second wavelength respectively input;
The first wavelength signal light demultiplexed and output by the first demultiplexer and the second wavelength signal light demultiplexed by the second demultiplexer and output are combined and output. A first multiplexer that
The second wavelength signal light output after being demultiplexed by the first demultiplexer and the first wavelength signal light output after being demultiplexed by the second demultiplexer are combined and output. A second multiplexer,
The optical transmission system according to claim 1, further comprising: The distribution side switching unit is
A first optical branching device for branching the signal light transmitted by the first optical line into two;
A second optical branching device for branching the signal light transmitted by the second optical line in two;
First light that selectively outputs one of the signal light branched and output by the first optical branching device and the one signal light branched and output by the second optical branching device A switch,
Second light that selectively outputs one of the other signal light branched and output by the first optical branching device and the other signal light branched and output by the second optical branching device. A switch,
A third optical branching device for branching the signal light output from the first optical switch;
A fourth optical branching device for branching the signal light output from the second optical switch;
The optical transmission system according to claim 1, further comprising: The distribution side switching unit is
A first optical branching device for branching the signal light transmitted through the first optical line into M branches;
A second optical branching device for M-branching the signal light transmitted by the second optical line;
Any one of the signal light outputted after being branched by M by the first optical branching device and any one of the signal light outputted by being branched by M by the second optical branching device is selectively outputted. M optical switches to
The optical transmission system according to claim 1, further comprising:   The optical transmission system according to claim 1, wherein the second optical transmitter has a variable wavelength of output signal light within a wavelength range including the first wavelength and the second wavelength. The transmitter further includes a third optical transmitter that outputs signal light of the first wavelength,
The transmission side switching unit selectively selects an optical connection between the first optical transmitter, the second optical transmitter, and the third optical transmitter and the first output end and the second output end. Switch to
The optical transmission system according to claim 1.

Images