JP5427870B2 - Optical add / drop multiplexer - Google Patents

Description

  The present invention relates to an optical add / drop multiplexer (OADM) that performs add / drop of signal light in an optical transmission network.

  As the demand for data communication increases, optical transmission networks using wavelength division multiplexing technology capable of transmitting large volumes of traffic are becoming widespread. In such an optical transmission network, as an optical transmission device, an optical cross connect device (OXC: Optical cross Connect) that switches the path of a path (signal light of a specific wavelength), a path branched from a ring network, or a path For example, an optical add / drop multiplexer or the like is used.

  FIG. 1 shows an example of a conventional optical add / drop multiplexer. As shown in FIG. 1, the optical add / drop multiplexer 10 includes an optical coupler 11, a 1 × N type wavelength selective switch (hereinafter referred to as WSS (wavelength selective switch)) 12, and an N × 1 type WSS 13. ing. The 1 × N-type WSS 12 has a function of inputting signal light from an input port and outputting signal light of an arbitrary wavelength to an arbitrary output port among the N output ports. It has a function of selecting an arbitrary wavelength from each signal light input from each of the input ports, multiplexing the wavelength, and outputting from the output port. Note that “arbitrary” means that it can be appropriately set by remote control or the like. In the following, “wavelength” may be used synonymously with “channel”.

  FIG. 2 is a functional configuration diagram of the 1 × N type WSS 12. As shown in FIG. 2, the 1 × N type WSS 12 includes a wavelength separation unit 15, a wavelength selection unit 16, and a wavelength multiplexing unit 17. The signal light input to the 1 × N type WSS 12 is separated at a predetermined optical frequency interval in the wavelength separation unit 15, and the wavelength selection unit 16 selects signal light of an arbitrary wavelength from the separated signal light. , Send to any output port. The wavelength multiplexing unit 17 multiplexes the signal light directed to each output port and outputs the multiplexed signal light from each output port. The N × 1 type WSS 13 corresponds to the input and output of the 1 × N type WSS 12 reversed.

  In the optical add / drop multiplexer 10 shown in FIG. 1, input signal light is coupler-branched by an optical coupler 11, one of which is input to a 1 × N-type WSS 12, and signal light having a specific wavelength in the 1 × N-type WSS 12. Is dropped as drop signal light. The other signal light branched by the optical coupler 11 is input to the N × 1-type WSS 13, and the signal light having the dropped wavelength is blocked, and another signal light is added from the client network side and multiplexed. Signal light is output.

  In the optical add / drop multiplexer 10 shown in FIG. 1, any wavelength can be assigned to each of the drop side output port and the add side input port. Therefore, the configuration shown in FIG. It is called a colorless configuration.

  FIG. 3 shows another configuration example of the optical add / drop multiplexer. As shown in FIG. 3, the optical add / drop multiplexer 20 includes an optical coupler 21, a duplexer 22, a duplexer 23, a 2 × 1 switch array 24, and a multiplexer 25. Here, the 2 × 1 switch array 24 is a switch array provided with 2 × 1 switches with two inputs and one output for the number of multiplexed wavelengths of signal light. A configuration including the duplexer 23, the 2 × 1 switch array 24, and the multiplexer 25 is referred to as an add switch unit.

  In this configuration, first, the signal light is branched by the optical coupler 21. One of the branched signal lights is input to the demultiplexer 22, and the signal light of each wavelength that has been wavelength-separated by the demultiplexer 22 is output from each output port of the demultiplexer 22.

  On the other hand, the other signal light output from the optical coupler 21 is input to the demultiplexer 23, and the signal light of each wavelength subjected to wavelength separation is output from each output port of the demultiplexer 23. Then, signal light of each wavelength is input to each 2 × 1 switch in the 2 × 1 switch array 24. From the client network side, the added signal light of a specific wavelength is input to the 2 × 1 switch corresponding to the wavelength. Then, the 2 × 1 switch corresponding to the add signal light added from the client network side selects and outputs the add signal light, and the other 2 × 1 switches are signals separated by wavelength by the duplexer 23. Output light. The signal light of each wavelength output from the 2 × 1 switch array 24 is input to the multiplexer 25 and multiplexed and output. As a result, signal light is added from the client network side.

  In the optical add / drop multiplexer 20 shown in FIG. 3, each wavelength corresponding to each output port of the drop-side demultiplexer 22 is fixed, and each wavelength corresponds to each input port of the add-side 2 × 1 switch array. Each wavelength to be fixed is also fixed. The configuration shown in FIG. 3 is called a colored configuration in the sense that the wavelength is fixed.

A. H. Gnauck, et.al., `` Spectrally efficient 1-Tb / s (25 x 42.7 Gb / s) RZ-DQPSK transmission over 28 100km SSMF Spans with 7 optica add / drops '', ECOC2004, PDTh4.4.1 E. Bert Basch, et.al., “Architectural tradeoffs for reconfigurable dense wavelength-division multiplexing systems”, JQE, Vol. 12, No. 4, JULY / AUGUST 2006

  Now, an optical add / drop multiplexer corresponding to signal light of 80 waves (optical frequency interval is 50 GHz) having a transmission rate per wave of 10 Gbps or 40 Gbps is being researched and developed (Non-patent Document 1). .

  In addition, due to the increase in traffic, it is necessary to increase the transmission speed per wave to 100 Gbps. When the transmission speed per wave is increased, the frequency band used for one wave increases, so it is necessary to increase the optical frequency interval (channel interval) from the current 50 GHz to 100 GHz and 200 GHz.

  As the speed increases, it is considered that 10 Gbps signal light, 40 Gbps signal light, and 100 Gbps signal light are mixed and transmitted on the optical transmission line. That is, signal light that can be transmitted at an optical frequency interval of 50 GHz and signal light that requires optical frequency intervals of 100 GHz and 200 GHz are mixed in the optical transmission line.

  Then, also in the optical add / drop multiplexer, it is necessary to add / drop the signal light of the channel having a desired optical frequency interval to the signal light in which the signal lights are mixed. However, in an ordinary single WSS, duplexer, multiplexer, etc., since the occupied frequency band per channel is fixed, the conventional configuration constituted by such a WSS, duplexer, multiplexer, etc. The optical add / drop multiplexer cannot perform desired add / drop on signal light in which signal lights of channels having different optical frequency intervals are multiplexed.

  The present invention has been made in view of the above points, and accommodates signal light in which channels having different optical frequency intervals are multiplexed, and enables addition / dropping to channels having desired optical frequency intervals. An object of the present invention is to provide an add / drop multiplexer.

  To solve the above problems, the present invention provides an optical add / drop multiplexer comprising a plurality of optical add / drop multiplexers including a first optical add / drop multiplexer and a second optical add / drop multiplexer. The first optical add / drop multiplexer has a function of performing an add / drop process for each channel of the first optical frequency interval, and the second optical add / drop multiplexer has the function A drop-side signal light input unit of the first optical add / drop multiplexer and the second light, each having a function of performing an add / drop process for each channel having a second optical frequency interval different from the first optical frequency interval. The signal light input unit on the drop side of the add / drop multiplexer is connected to an optical coupler that inputs the signal light to be processed by the optical add / drop multiplexer, and the adder of the first optical add / drop multiplexer is added. Side signal light output section and the second optical add / drop multiplexer A signal light output unit on the add side of the stage is connected to an optical coupler that outputs the signal light after the add / drop processing of the optical add / drop multiplexer. The

  The present invention also provides a first optical coupler for branching input signal light, and a plurality of wavelength separation means connected to the first optical coupler and having different optical frequency intervals of channels to be subjected to wavelength separation. A second optical coupler that outputs the signal light after the add / drop process, and a plurality of wavelength synthesizing units that are connected to the second optical coupler and that have different optical frequency intervals of channels to be subjected to wavelength synthesis, The signal light connected to the first optical coupler and the second optical coupler, and received from the first optical coupler, blocks signal light output as drop signal light in the plurality of wavelength separation means, Wavelength blocking means for sending the signal light after blocking to the second optical coupler can also be configured as an optical add / drop multiplexer.

  In the optical add / drop multiplexer, one or more of the plurality of wavelength demultiplexing units and the plurality of wavelength synthesizing units may be wavelength selective switches.

  In addition, the wavelength block means transmits signal light for each optical frequency interval that is half of the optical frequency interval of the channel having the smallest optical frequency interval among the channels included in the signal light input to the optical add / drop multiplexer. It is good also as providing the function to perform level adjustment.

The present invention is also connected to a wavelength selective switch that receives signal light from an input port and uses one channel having a bandwidth of a first optical frequency interval as a unit of wavelength selection, and an output port of the wavelength selective switch. Wavelength separation means having at least one channel having a bandwidth of a second optical frequency interval that is a half or a quarter of the first optical frequency interval as a unit of wavelength separation. A drop means for dropping the signal light and the signal light output from another output port of the wavelength selective switch, combining the wavelength of the signal light and the add signal light, and outputting the wavelength-combined signal light And an optical add / drop multiplexer. A wavelength selective switch may be used as the wavelength separation means.

  Further, the add means inputs the signal light output from the wavelength selective switch from an input port, and uses a wavelength selective switch having the channel of the first optical frequency interval as a unit of wavelength selection, and the wavelength selective switch It is also possible to provide at least wavelength combining means connected to another input port and having the second optical frequency interval smaller than the first optical frequency interval as a unit of wavelength combining and inputting add signal light Good.

  Further, the present invention wavelength-separates the input signal light, drop means for outputting the drop signal light from the wavelength-separated signal light, signal light obtained by removing the drop signal light from the input signal light, Alternatively, a signal light obtained by coupler-branching the input signal light is input from an input port, and a wavelength selection switch having a channel of the first optical frequency interval as a unit of wavelength selection and another input port of the wavelength selection switch And an add unit comprising at least a wavelength synthesizing unit for inputting an add signal light, wherein the channel having a second optical frequency interval smaller than the first optical frequency interval is connected as a unit of wavelength synthesis. It can also be configured as an optical add / drop multiplexer characterized by the following. A wavelength selective switch may be used as the wavelength synthesizing means.

  According to the present invention, there is provided an optical add / drop multiplexer capable of accommodating signal light multiplexed with channels having different optical frequency intervals and performing add / drop on a channel having a desired optical frequency interval. Is possible.

It is a figure which shows the example of a structure of the conventional optical add / drop multiplexer. It is a functional block diagram of WSS. It is a figure which shows the example of a structure of the conventional optical add / drop multiplexer. 1 is a configuration diagram of an optical add / drop multiplexer according to Embodiment 1-1. FIG. It is a figure which shows the signal arrangement example 1. FIG. It is a figure which shows the example 2 of signal arrangement | positioning. It is a block diagram of the optical add / drop multiplexer according to Embodiment 1-2. It is a block diagram of the optical add / drop multiplexer according to Embodiment 1-3. It is a block diagram of the optical add / drop multiplexer according to Embodiment 2-1. FIG. 10 is a configuration diagram of another example of the optical add / drop multiplexer according to Embodiment 2-1. It is a block diagram of the optical add / drop multiplexer according to Embodiment 2-2. It is a block diagram of the other example of the optical add / drop multiplexer based on Embodiment 2-2. FIG. 3 is a configuration diagram of an optical add / drop multiplexer according to Embodiment 3-1. FIG. 10 is a configuration diagram of an optical add / drop multiplexer according to Embodiment 3-2. It is a block diagram of the optical add / drop multiplexer according to Embodiment 4-1. It is a block diagram of the optical add / drop multiplexer according to Embodiment 4-2. It is a figure which shows the summary of each structure. It is a figure which shows the summary of each structure. It is a figure which shows the summary of each structure.

  Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals are assigned to components having the same function.

(Embodiment 1-1)
FIG. 4 is a configuration diagram of the optical add / drop multiplexer according to Embodiment 1-1 of the present invention. As shown in FIG. 4, the optical add / drop multiplexer 30 includes an optical coupler 31, a 1 × N type drop WSS 32 (50 GHz interval), and an N × 1 type add WSS 33 (50 GHz interval). An optical add / drop multiplexer 34 for intervals, an optical coupler 35, a 1 × N type drop WSS 36 (100 GHz interval), and an N × 1 type add WSS 37 (100 GHz interval), and an optical branch for 100 GHz interval An optical multiplexer / demultiplexer 42 for 200 GHz intervals having an insertion multiplexer 38, an optical coupler 39, a 1 × N type drop WSS 40 (200 GHz interval), and an N × 1 type add WSS 41 (200 GHz interval). Are configured to be connected in parallel by the optical coupler 43 and the optical coupler 44.

  Here, the WSS for the 50 GHz interval is a WSS that can separate and switch the signal light in units of the optical frequency band of 50 GHz in the configuration shown in FIG. The optical add / drop multiplexer for 50 GHz intervals is an apparatus suitable for performing add / drop on signal light (wavelength multiplexed signal light) in which channels are arranged at 50 GHz intervals. The same applies to 100 GHz intervals and 200 GHz intervals. In this embodiment (the same applies to the other embodiments), the channel interval of 50 GHz is used when transmission is performed at a transmission rate of 10 Gbps per wave. It is described. “For 40 Gbps” and “for 100 Gbps” have the same meaning.

  Each WSS has a configuration as described with reference to FIG. 2, and the wavelength demultiplexing unit 15 and the wavelength multiplexing unit 17 can be configured using, for example, an AWG or a diffraction grating. For example, it can be configured using a MEMS or a liquid crystal switch. The same applies to other embodiments.

  In the optical add / drop multiplexer 30 shown in FIG. 4, the input signal light is branched in three directions by the optical coupler 43 and input to the optical coupler 31, the optical coupler 35, and the optical coupler 39, respectively. Each of the optical coupler 31, the optical coupler 35, and the optical coupler 39 is a signal light input unit on the drop side. In the same manner as in the configuration shown in FIG. 1, the signal light input to the optical coupler 31 is branched, one is input to the drop WSS 32, the signal light of a specific wavelength is dropped, and the other signal branched. The light is input to the add WSS 33, multiplexed with the added signal light, output from the output port, and reaches the optical coupler 44. The output port of the add WSS 33 is an example of an add-side signal light output unit. The add / drop process is similarly performed on the signal light input to the other optical couplers 35 and 39. However, the optical frequency band which is a unit of optical signal processing (separation, switch, synthesis) is different. The optical coupler 44 that has received the signal light output from each add WSS multiplexes the signal light and sends it to the optical transmission line.

  According to the configuration shown in FIG. 4, the signal light is branched by the optical coupler 43, and the add / drop process corresponding to each optical frequency interval is performed in each branch route. In signal light in which channels are mixed, it is possible to freely add and drop channels with desired optical frequency intervals.

  Here, an example of a method for arranging the signal light on the optical frequency axis in the present embodiment will be described.

<Signal arrangement example 1>
A signal arrangement example 1 will be described with reference to FIG. In the signal arrangement example 1, the center frequency of the signal light at each transmission speed is arranged on the ITU grid. As shown in FIG. 5A, in the case of 100 Gbps signal light, the center frequency of the signal light is arranged on a grid at intervals of 200 GHz. If the signal is 40 Gbps, the center frequency of the signal is arranged on a grid at intervals of 100 GHz. If the signal is 10 Gbps, the center frequency of the signal is arranged on a grid at intervals of 50 GHz. As shown in FIG. 5A, the pass band of MUX / DEMUX (multiplexing and demultiplexing) corresponding to each signal light is shifted for each signal light.

  Further, for example, 100 Gbps signal light A (one wave), 40 Gbps signal lights B and C (two waves), and 10 Gbps signals D to G (four waves) are shown in each frequency grid (dotted line) shown in FIG. When these are multiplexed, the arrangement is as shown in FIG. 5 (b). As indicated by J and K in FIG. 5B, when signal lights having different optical frequency intervals are arranged on the grid, an optical frequency band that is not used for signal transmission is generated.

  Further, as shown in FIG. 5A, since the pass band of MUX / DEMUX is shifted for each signal light, for example, when one type of WSS that separates / multiplexes signal light in units of 200 GHz band is used, The signal lights B and C and the signal lights D to G cannot be extracted or multiplexed. However, in the configuration in which various optical add / drop multiplexers are connected in parallel as in the present embodiment 1-1 and later described embodiments 1-2 and 1-3, the respective optical add / drop multiplexers are respectively connected. Therefore, the signal shown in FIG. 5 can be processed.

  The signal arrangement example 1 is called a center frequency grid fixed type because the center frequency of the signal light is fixed to the grid.

<Signal arrangement example 2>
A signal arrangement example 2 will be described with reference to FIG. The signal arrangement example 2 does not attempt to arrange all the signal lights on the ITU grid, but the position of the optical frequency of each signal light is a WSS or a duplexer in which the occupied frequency band for each channel is fixed. These are arranged so as to fit the pass band of the multiplexer, and this arrangement is called “occupied band fixed type”.

  In the example of FIG. 6A, signal light at intervals of 200 GHz is arranged on a 200 GHz grid. The signal light at intervals of 100 GHz is arranged at a position of 100 GHz grid + 50 GHz, and as a result, two signal lights are arranged in a band of 200 GHz. Further, the signal light at intervals of 50 GHz is arranged at a position of 50 GHz grid + 25 GHz, and as a result, four signal lights are arranged in a band of 200 GHz.

  When these signal lights are multiplexed, the result is as shown in FIG. 6B, and the unused band portion shown in FIG. 5B is eliminated. Further, in the case of the signal light shown in FIG. 6B, for example, each of the signal lights L, M, and N can be cut by a WSS that processes the signal light at intervals of 200 GHz, a demultiplexer, etc. It is possible to take out signal light of a desired band from the inside.

  Also, for example, in the WSS that processes 200 GHz signal light shown in FIG. 6A, the center frequency when performing optical signal processing is set to a value of a 200 GHz grid, and the transmission bandwidth is set to 200 GHz. In WSS that processes signal light of 100 GHz, the center frequency is set to a value of 100 GHz grid + 50 GHz, and the transmission bandwidth is set to 100 GHz. In WSS that processes 50 GHz signal light, the center frequency may be set to a value of 50 GHz grid + 25 GHz, and the transmission bandwidth may be set to 50 GHz.

  Needless to say, the configurations of the embodiments 1-1, 1-2, and 1-3 can correspond to the signal light arranged in the signal arrangement example 2.

(Embodiment 1-2)
FIG. 7 is a block diagram of an optical add / drop multiplexer according to Embodiment 1-2. As shown in FIG. 7, the optical add / drop multiplexer 50 includes an optical coupler 31, a drop demultiplexer 51 (50 GHz interval), an N × 1 type add WSS 33 (50 GHz interval), and an add multiplexer. An optical add / drop multiplexer 57 for a 50 GHz interval having a counter 52 (50 GHz interval), an optical coupler 35, a drop duplexer 53 (100 GHz interval), an N × 1 type add WSS 37 (100 GHz interval), and An optical add / drop multiplexer 58 for 100 GHz interval having an add multiplexer 54 (100 GHz interval), an optical coupler 39, a drop demultiplexer 55 (200 GHz interval), an N × 1 type add WSS 41 (200 GHz) The optical coupler 43 and the optical coupler 44 are connected in parallel to the optical add / drop multiplexer 59 for the 200 GHz interval having the (interval) and add multiplexer 56 (200 GHz interval).

  In the optical add / drop multiplexer 50 shown in FIG. 7, the drop WSS of the optical add / drop multiplexer 30 in Embodiment 1-1 is replaced with a drop duplexer, and the add WSS is added to the add WSS. This is a configuration in which containers are connected and has a colored configuration.

  Also in the optical add / drop multiplexer 50 shown in FIG. 7, the signal light is branched by the optical coupler in the same manner as in the embodiment 1-1, and the signal light is added / dropped corresponding to each optical frequency interval in each branch route. Since the processing is performed, it is possible to perform add / drop on a channel having a desired optical frequency interval in signal light obtained by multiplexing channels having mixed optical frequency intervals.

  In the present embodiment, in branching using an optical coupler on the input side, the branching ratio is determined in consideration of the sensitivity of the PD provided at the branching destination, and the branching ratio is adjusted so as not to cause optical loss as much as possible. Furthermore, when an optical signal is output from the output-side optical insertion device, signal levels having different wavelengths are equalized and output.

(Embodiment 1-3)
FIG. 8 is a block diagram of an optical add / drop multiplexer according to Embodiment 1-3. This optical add / drop multiplexer 60 replaces the add side with an add switch unit in the optical add / drop multiplexer corresponding to each optical frequency interval in the optical add / drop multiplexer 50 according to Embodiment 1-2. It is a thing. The operation of the optical add / drop multiplexers 64 to 66 corresponding to each optical frequency interval is the same as the operation of the configuration described in FIG. This configuration is a colored configuration similar to the configuration shown in FIG.

  In Embodiments 1-1 to 1-3, the configuration for solving the problems of the present invention by connecting the optical add / drop multiplexers in parallel via optical couplers has been described. The optical add / drop multiplexer is not limited to those shown in the embodiments 1-1 to 1-3. What is the configuration of each optical add / drop multiplexer connected in parallel if each optical add / drop multiplexer connected in parallel is compatible with signal light having different optical frequency intervals? May be. For example, any of the optical add / drop multiplexers described in this specification may be used as the optical add / drop multiplexers connected in parallel.

  In Embodiments 1-1 to 1-3 described above, the number of optical add / drop multiplexers connected in parallel via optical couplers is three, but the number is not limited to three. The number may be arbitrarily determined according to the type of channel multiplexed on the light (transmission rate type). However, the number is two or more.

  In the present embodiment, in branching using an optical coupler on the input side, the branching ratio is determined in consideration of the sensitivity of the PD provided at the branching destination, and the branching ratio is adjusted so as not to cause optical loss as much as possible. Furthermore, when an optical signal is output from the output-side optical insertion device, signal levels having different wavelengths are equalized and output.

(Embodiment 2-1)
FIG. 9 shows a configuration diagram of an optical add / drop multiplexer according to Embodiment 2-1 of the present invention. As shown in FIG. 9, this optical add / drop multiplexer 70 includes a 1 × N drop WSS 71 (200 GHz interval), a 1 × N drop WSS 72 (100 GHz interval), and a 1 × N drop drop. WSS73 (50 GHz interval), optical coupler 74 connected to these WSSs, N × 1 type ad WSS75 (200 GHz interval), N × 1 type ad WSS76 (100 GHz interval), N × 1 type ad WSS 77 (50 GHz interval), an optical coupler 78 connected to these WSSs, and a wavelength blocker 79 (WB: Wavelength Blocker) of 25 GHz interval connected to both optical couplers.

  Although FIG. 9 shows transponders connected to each WSS, the transponders may not be components of the optical add / drop multiplexer according to the embodiment of the present invention. The same applies to other figures in which the transponder is shown.

  The wavelength blocker 79 has a function of adjusting the level of signal light of an arbitrary wavelength at intervals of 25 GHz. In the optical add / drop multiplexer 70, the signal light to be dropped is blocked and other signal light is transmitted. It works to let you.

  In the configuration shown in FIG. 9, the signal light input to the optical coupler 74 is branched toward each drop WSS and the wavelength blocker 79.

  The signal light branched toward each drop WSS is dropped in each drop WSS in units of channels having optical frequency intervals corresponding to each drop WSS. That is, in the drop WSS 71 (200 GHz interval), a 100 Gbps signal light having a predetermined wavelength is dropped, and in the drop WSS 72 (100 GHz interval), a 40 Gbps signal light is dropped, and the drop WSS 73 (50 GHz interval). ), 10 Gbps signal light is dropped.

  The wavelength blocker 79 receives the signal light branched by the optical coupler 74, blocks the wavelength dropped in the drop WSSs 71 to 73, and transmits other wavelengths. The signal light output from the wavelength blocker is input to the optical coupler 78. On the other hand, each of the add-use WSSs 75 to 77 outputs signal light of channels corresponding to the optical frequency intervals, and these signal light and the signal light output from the wavelength blocker 79 are multiplexed in the optical coupler 78. Is output.

  With the configuration and operation as described above, it is possible to perform add / drop on a channel having a desired optical frequency interval in signal light in which channels having different optical frequency intervals are mixed.

  The optical add / drop multiplexer 70 in the present embodiment can be applied to both the center frequency grid fixed type signal arrangement example 1 (FIG. 5) and the occupied band fixed type signal arrangement example 2 (FIG. 6).

  In the case of the signal arrangement of the fixed center frequency grid type, for example, as shown in FIG. 5B, when all the signals at intervals of 50 GHz are dropped with respect to the signal light multiplexed with each signal light, In the wavelength blocker 79, it is necessary not only to block the signals D to G at intervals of 50 GHz but also to block the light in the empty band K shown in FIG. If this is not blocked, for example, when 100 GHz signal light adjacent to 100 GHz signal lights B and C is added on the add side, noise is generated for the signal light. For this reason, the wavelength blocker 79 in the present embodiment enables level adjustment at 25 GHz intervals, which is half of the minimum optical frequency interval (50 GHz). The transmission spectrum of the wavelength blocker 79 is flat.

  FIG. 10 is a diagram showing an optical add / drop multiplexer 80 in which the wavelength blocker 79 is replaced with a wavelength blocker 81 having an interval of 50 GHz in the optical add / drop multiplexer 70 shown in the present embodiment. The rest is the same as FIG. In the configuration shown in FIG. 10, since the 25 GHz band cannot be selected and blocked, it cannot be applied to the center frequency grid fixed signal arrangement, and can be applied only to the occupied band fixed signal arrangement.

  In the present embodiment, in branching using an optical coupler on the input side, the branching ratio is determined in consideration of the sensitivity of the PD provided at the branching destination, and the branching ratio is adjusted so as not to cause optical loss as much as possible. Furthermore, when an optical signal is output from the output-side optical insertion device, signal levels having different wavelengths are equalized and output.

(Embodiment 2-2)
FIG. 11 shows a configuration diagram of an optical add / drop multiplexer according to Embodiment 2-2. As shown in FIG. 9, in the configuration shown in FIG. 9 of Embodiment 2-1, this optical add / drop multiplexer 90 replaces drop WSSs 71-73 with drop demultiplexers 91-93, and adds WSS 75. ˜77 are replaced with add multiplexers 94-96. Although the embodiment 2-1 has a colorless configuration and the embodiment 2-2 has a colored configuration, the operation related to the add / drop is the same. Similarly to the configuration shown in FIG. 9, the configuration shown in FIG. 11 uses a wavelength blocker 79 with an interval of 25 GHz. Therefore, the configuration shown in FIG. it can.

  FIG. 12 is a diagram showing an optical add / drop multiplexer 100 using a wavelength blocker 81 at 50 GHz intervals in place of the wavelength blocker 79 at 25 GHz intervals in the present embodiment. Similar to the configuration shown in FIG. 10, this case can be applied only to the fixed band signal arrangement.

  In Embodiments 2-1 and 2-2, a configuration in which WSS is used on the drop side, a multiplexer is used on the add side, a duplexer is used on the drop side, and WSS is used on the add side. It can also be set as the structure to do. Furthermore, a multiplexer and WSS can be mixed, or a duplexer and WSS can be mixed.

  In the present embodiment, in branching using an optical coupler on the input side, the branching ratio is determined in consideration of the sensitivity of the PD provided at the branching destination, and the branching ratio is adjusted so as not to cause optical loss as much as possible. Furthermore, when an optical signal is output from the output-side optical insertion device, signal levels having different wavelengths are equalized and output.

(Embodiment 3-1)
FIG. 13 is a configuration diagram of the optical add / drop multiplexer according to Embodiment 3-1 of the present invention. As shown in FIG. 10, this optical add / drop multiplexer 110 includes a drop WSS 101 (200 GHz interval), a drop WSS 102 (100 GHz interval), a drop WSS 103 (50 GHz interval), an add WSS 104 (200 GHz interval), an add WSS105 (100 GHz interval) and AD WSS106 (50 GHz interval), drop WSS102 (100 GHz interval) and drop WSS (50 GHz interval) 103 are connected to drop WSS101 (200 GHz interval), and add WSS105 ( 100 GHz interval) and WSS 106 for advertisement (50 GHz interval) are connected to WSS 104 for advertisement (200 GHz interval). Also, drop WSS101 (200 GHz interval) and add WSS104 (200 GHz interval) are connected, drop WSS102 (100 GHz interval) and add WSS105 (100 GHz interval) are connected, drop WSS103 (50 GHz interval) and add WSS 106 (50 GHz interval) is connected.

  In this optical add / drop multiplexer 110, the drop WSS 101 (at intervals of 200 GHz) to which signal light has been input performs wavelength selective switch processing in units of the optical frequency band of 200 GHz. That is, of the signal light multiplexed on the input signal light, the dropped 100 Gbps signal light is output from the output port connected to the 100G transponder. Also, the drop WSS 101 (200 GHz interval) receives signal light (which may include a plurality of channels) of a 200 GHz optical frequency interval including 40 Gbps drop signal light from the output port to which the drop WSS 102 (100 GHz interval) is connected. Outputs signal light of a channel of 200 GHz optical frequency interval including a drop signal light of 10 Gbps (which may include a plurality of channels) from an output port connected to the drop WSS 103 (50 GHz interval).

  Further, the drop WSS 101 (200 GHz interval) directs the signal light obtained by removing the signal light of the 200 GHz optical frequency interval channel output to the drop side from the input signal light to the add WSS 104 (200 GHz interval). And send it out. The drop WSS 102 (100 GHz interval) drops the signal light of the 100 GHz interval channel to be dropped from the signal light of the 200 GHz optical frequency interval channel received from the drop WSS 101 (200 GHz interval), and the 100 GHz interval is not dropped. Only the signal light of the first channel is sent to the add WSS 105 (100 GHz interval). Further, the drop WSS 103 (50 GHz interval) drops the signal light of the channel of 50 GHz interval to be dropped from the signal light of the channel of 200 GHz optical frequency interval received from the drop WSS 101 (200 GHz interval), and is not dropped. Only the signal light of the channel at intervals of 50 GHz is transmitted toward the WSS 106 for add (at intervals of 50 GHz).

  The add WSS 106 (50 GHz interval) sends the signal light received from the drop WSS 103 (50 GHz interval) and the added signal light to the add WSS 104 (200 GHz interval). The WSS 105 (100 GHz interval) sends the signal light multiplexed from the signal light received from the drop WSS 102 (100 GHz interval) and the added signal light toward the add WSS 104 (200 GHz interval). The add WSS 104 (200 GHz interval) includes the signal light received from the drop WSS 101 (200 GHz interval), the signal light received from the add WSS 105 (100 GHz interval), and the signal received from the add WSS 106 (50 GHz interval). The light and the signal light added directly to the add WSS 104 (at 200 GHz interval) are multiplexed and transmitted to the optical transmission line.

  For example, in the case of receiving signal light in which the signal light is arranged in the occupation band fixed type shown in FIG. 6B, it is assumed that the signal lights X and Y are dropped and the signal light at the same position is added. . In this case, the drop WSS 101 (200 GHz interval) outputs the channel M and the channel N at 200 GHz intervals to the drop WSS 102 (100 GHz interval) and the drop WSS 103 (50 GHz interval), respectively. The drop WSS 102 (100 GHz interval) drops the channel X signal light at 100 GHz intervals and transmits the channel P signal to the add WSS 105 (100 GHz interval). The drop WSS 103 (50 GHz interval) drops the channel Y signal light at 50 GHz intervals and transmits the channel H, I, and R signal lights to the add WSS 106 (50 GHz interval).

  The signal light corresponding to the frequency position of the dropped channel is added to the add WSS 105 (100 GHz interval) and the add WSS 106 (50 GHz interval), and multiplexed with the signal light received from the drop-side WSS 104 (add WSS 104 ( In the add WSS 104 (200 GHz interval), the signal light as shown in FIG. 6B is generated again and output by multiplexing the input signal light.

  As described above, the optical add / drop multiplexer 110 according to the present embodiment 3-1 is configured by hierarchically connecting WSSs having different optical frequency intervals to be processed. It can be applied to the fixed band fixed type that can arrange the signal light so that it includes multiple small bands, but it is implemented in the center frequency grid fixed type signal arrangement that can not make the relationship between the signal light of different frequency intervals like this The configuration of Form 3-1 cannot be applied.

(Embodiment 3-2)
FIG. 14 is a configuration diagram of an optical add / drop multiplexer according to Embodiment 3-2 of the present invention. As shown in FIG. 14, this optical add / drop multiplexer 120 includes a drop WSS 101 (200 GHz interval), a drop demultiplexer 111 (200 GHz interval), a drop demultiplexer 112 (100 GHz interval), a drop demultiplexer. There are a duplexer 113 (50 GHz interval), an add WSS104 (200 GHz interval), an add multiplexer 114 (200 GHz interval), an add multiplexer 115 (100 GHz interval), and an add multiplexer 116 (50 GHz interval). Then, the drop WSS 101 (200 GHz interval) and the add WSS 104 (200 GHz interval) are connected.

  In this optical add / drop multiplexer 120, the drop WSS 101 (at intervals of 200 GHz) to which signal light has been input performs wavelength selective switch processing in units of channels of 200 GHz optical frequency intervals. That is, out of the signal light multiplexed with the input signal light, the signal light multiplexed with the 100 Gbps signal light to be dropped is output from the output port to which the drop duplexer 111 (200 GHz interval) is connected. In addition, the drop WSS 101 (200 GHz interval) is connected to a drop demultiplexer 112 (100 GHz interval) for signal light of a channel of 200 GHz optical frequency interval including a 40 Gbps drop signal light (which may include a plurality of channels). Output from the output port, and output signal light (which may include a plurality of channels) of 200 GHz optical frequency intervals including 10 Gbps drop signal light from the output port to which the drop duplexer 113 (50 GHz interval) is connected. .

  Each drop demultiplexer demultiplexes the signal light of the optical frequency interval channel to be processed by itself and outputs the demultiplexed signal light to the corresponding transponder.

  Further, the drop WSS 101 (200 GHz interval) directs the signal light obtained by removing the signal light of the 200 GHz optical frequency interval channel output to the drop side from the input signal light to the add WSS 104 (200 GHz interval). And send it out.

  On the other hand, the add WSS 104 (200 GHz interval) uses the signal light obtained by multiplexing the signal light received from the drop WSS 101 (200 GHz interval) and the add signal light transmitted from the multiplexers 114 to 116 as an optical transmission line. Send it out. This Embodiment 3-2 is different from Embodiment 3-1 in that it has a colored configuration.

(Embodiment 4-1)
FIG. 15 is a configuration diagram of the optical add / drop multiplexer according to Embodiment 4-1 of the present invention. As shown in the figure, this optical add / drop multiplexer 130 includes an optical coupler 124, a drop WSS 121 (200 GHz interval), a drop WSS 122 (100 GHz interval), a drop WSS 123 (50 GHz interval), and an add WSS 104 (200 GHz interval). ), WSS 105 for add (100 GHz interval), WSS 106 for add (50 GHz interval), WSS 121 for drop (200 GHz interval), WSS 122 for drop (100 GHz interval), WSS 123 for drop (50 GHz interval), and WSS 104 for add ( 200 GHz interval) is connected to the optical coupler 124, and the ad WSS 105 (100 GHz interval) and the ad WSS 106 (50 GHz interval) are connected to the ad WSS 104 (200 GHz interval).

  As shown in FIG. 15, the configuration on the drop side in this optical add / drop multiplexer 130 corresponds to the type of channel (optical frequency interval, type of transmission rate), as in the configuration of the embodiment 1-1. Each drop WSS is connected in parallel by an optical coupler 124, and the add-side configuration in this optical add / drop multiplexer 130 is similar to the configuration shown in FIG. It is the structure connected hierarchically.

  In this optical add / drop multiplexer 130, the signal light branched by the optical coupler 124 is input to each drop WSS, and each drop WSS drops signal light in units of channels corresponding to optical frequency intervals. Is extracted and output.

  On the other hand, on the add side, each of the add WSS 105 (50 GHz interval) and the add WSS 106 (100 GHz interval) receives the add signal light in units of channels of the respective optical frequency intervals and multiplexes them to add the WSS 104 (200 GHz interval). To send. The add WSS 104 (200 GHz interval) includes signal light obtained by removing signal light of a channel at 200 GHz intervals including signal light dropped on the drop side from the signal light input from the optical coupler 124, and add WSS 106 (50 GHz). Interval) and the signal light received from each of the add-use WSSs 105 (100 GHz interval).

  Since the configuration of the embodiment 4-1 has a hierarchical configuration on the add side, it can be applied only to a fixed band fixed type signal arrangement.

  In the present embodiment, in branching using an optical coupler on the input side, the branching ratio is determined in consideration of the sensitivity of the PD provided at the branching destination, and the branching ratio is adjusted so as not to cause optical loss as much as possible. Furthermore, when an optical signal is output from the output-side optical insertion device, signal levels having different wavelengths are equalized and output.

(Embodiment 4-2)
FIG. 16 is a configuration diagram of an optical add / drop multiplexer according to Embodiment 4-2 of the present invention. As shown in FIG. 16, the optical add / drop multiplexer 140 corresponds to a configuration in which the drop WSS 101 (200 GHz interval) is replaced with an optical coupler 131 in the configuration shown in FIG. 14 of the embodiment 3-2. .

  In this optical add / drop multiplexer 140, the signal light branched by the optical coupler 131 is input to the drop demultiplexers 111 to 113, and the signal light is demultiplexed at the corresponding optical frequency intervals. Is output.

  On the add side, the add-use WSS 104 (at intervals of 200 GHz) includes signal light from the signal light input from the optical coupler 131 excluding signal light of channels at intervals of 200 GHz including the signal light dropped on the drop side. The add signal light transmitted from the wavers 114 to 116 is multiplexed and transmitted to the optical transmission line. Since this configuration also has a hierarchical configuration on the add side, it can be applied only to the fixed band signal arrangement.

  In the present embodiment, in branching using an input-side optical coupler, the branching ratio is determined in consideration of the sensitivity of the PD provided at the branching destination, and the branching ratio is adjusted so as not to cause optical loss as much as possible. Furthermore, when an optical signal is output from the output-side optical insertion device, signal levels having different wavelengths are equalized and output.

  In the above embodiments 2-1 to 4-2, the configuration using three types of WSS, duplexer, and multiplexer for 200 GHz interval, 100 GHz interval, and 50 GHz interval is shown. The number is not limited to three, and may be arbitrarily determined according to the type of channel multiplexed on the signal light (the type of transmission speed). However, the number is two or more.

(Summary)
A summary of the configurations shown in the embodiments 2-1 to 4-2 described above from the viewpoint of whether WSS is used on the drop side and the add side or whether an optical coupler is used. It is shown in FIGS. FIG. 17 shows a configuration that can be used only for a signal arrangement with a fixed occupied band. FIG. 18 shows a configuration that can be applied not only to a signal arrangement with a fixed occupied band but also to a signal arrangement with a fixed center frequency grid. Each figure shows an image of the corresponding configuration. In FIG. 17, the add-side coupler and drop-side WSS are configured by, for example, reversing the add side and the drop side in the configurations of the embodiments 4-1 and 4-2, and using a hierarchical configuration on the drop side. An optical coupler branch configuration is used on the side.

  In addition, Embodiments 1-1 to 1-3 are applicable to not only the fixed band fixed signal arrangement but also the center frequency grid fixed type signal arrangement, and as described above, in parallel by the optical coupler. The configuration of each connected optical add / drop multiplexer is not limited to a specific one.

  FIG. 19 shows a diagram summarized from another viewpoint. FIG. 19 is a diagram summarizing the features of each component and the colorless, colored, and usable signal arrangements for each feature. Since the configurations of the embodiments 2-1 and 2-2 using the wavelength blocker include a configuration in which WSSs or the like targeted for channels having different optical frequency intervals are connected via an optical coupler to form another route. Classification as shown in FIG.

  The present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the claims.

11, 21, 31, 35, 39, 43, 44, 74, 78, 124, 131 Optical coupler 12, 32, 36, 40, 71-73, 101-103, 121-123 WSS for drop
13, 33, 37, 41, 75-77, 104-106, WSS for ads
22, 23, 51, 53, 55, 91-93, 111-113 Demultiplexer 25, 52, 54, 56, 94-96, 114-116 Multiplexer 10-140 Optical add / drop multiplexer 15 Wavelength separation Unit 16 wavelength selection unit 17 wavelength multiplexing unit 24 SW array 79, 81 wavelength blocker

Claims (3)

Signal light is input from an input port, and connected to a wavelength selective switch having one channel having a bandwidth of a first optical frequency interval as a wavelength selection unit, and an output port of the wavelength selective switch, and the first light Drop means for dropping signal light, comprising at least wavelength separation means having one channel having a bandwidth of a second optical frequency interval that is a half or a quarter of the frequency interval as a unit of wavelength separation. When,
Add means for receiving signal light output from another output port of the wavelength selective switch, performing wavelength synthesis of the signal light and the add signal light, and outputting the wavelength synthesized signal light;
An optical add / drop multiplexer comprising:   2. The optical add / drop multiplexer according to claim 1, wherein the wavelength demultiplexing means is a wavelength selective switch.   The add means inputs the signal light output from the wavelength selective switch from an input port, and selects a wavelength selective switch having a channel of the first optical frequency interval as a unit of wavelength selection, and another wavelength selective switch A wavelength synthesizing unit for inputting an add signal light, wherein the channel of the second optical frequency interval smaller than the first optical frequency interval is connected to an input port and the channel of the second optical frequency interval is set as a unit of wavelength synthesis; The optical add / drop multiplexer according to claim 1.

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