JPH0353226A - Optical branch/insertion node - Google Patents

Abstract

PURPOSE:To easily execute the branch and the insertion of an optical signal having a different speed by allowing an optical signal of prescribed wavelength to branch from an inputted wavelength multiple optical signal, and also, converting the optical signal into prescribed wavelength, and thereafter, inserting it and outputting the wavelength multiple optical signal. CONSTITUTION:Optical branch/insertion nodes 100, 101 allow an optical signal of prescribed wavelength to branch from an inputted wavelength multiple optical signal to the other optical branch/insertion node, and can insert an optical signal from the other optical branch/insertion node into an optical signal of other wavelength than prescribed wavelength which is allowed to branch. Accordingly, since a wavelength multiple optical signal can be used, it will suffice that an operating speed requested by an optical device is a low speed, and also, the wavelength multiple optical signal can be used. In such a way, with regard to the multiple optical signal in which each signal speed is different at every wavelength, as well, the branch and the insertion can be executed easily.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an optical branching and adding method for branching and adding predetermined optical signals.
Regarding insertion nodes. (Prior art) Optical communications using optical fibers as transmission paths are expected to become widely used in the future, as they are capable of transmitting large amounts of information due to the broadband and non-inductive properties of optical fibers. Ru. By introducing optical signal processing technology into such optical communication networks and adding various functions, optical branching and
Insertion nodes are being considered. As one such optical branch/add node, there has been a
8-63 pp. As described in 1-6, an optical system that branches an optical signal in an arbitrary time slot of a time-division multiplexed optical signal to a terminal or other node, and inserts an optical signal from the terminal or other node into an empty time slot. Branch/insert nodes have been proposed. Figure 5 shows a treetop diagram of such a conventional optical drop/add node. FIG. 5 shows an example of a configuration in which an optical signal in a predetermined time slot is switched between two time-division multiplexed highways. Below, we will explain the treetop precepts and actions. The time division multiplexed optical signal 510 is sent to an optical drop/add node 500
One of the time division multiplexed optical signals branched by the branching device 520 is branched by the branching device 520 in the branching device 520 to the optical clock extraction circuit 530. The data is sent to the erase circuit 560. The optical clock extraction circuit 530 extracts an optical clock signal from the other time division multiplexed optical signal branched by the splitter 520 and sends the optical clock to the optical frequency divider 540. The optical frequency divider 540 creates an optical multiplexed frame signal from the optical clock signal from the optical clock extraction circuit 530, and sends the optical multiplexed frame signal to the optical latch circuit i15 via the brancher 522.
Send to 50,551. The optical latch circuit 550 synchronizes the optical signal of a desired time slot of the time division multiplexed optical signal from the splitter 521 with the optical multiplexed frame signal input from the optical frequency divider 540 through the splitter 522. Optical branch/
Emit to insertion node 501. On the other hand, the optical erasing circuit 560 erases only the optical signal of the desired time slot branched by the optical latch circuit 550 from the time division multiplexed signal inputted through the branching device 521, thereby creating an empty time slot and The optical signal of the time slot is emitted to the combiner 570. Then, the optical latch circuit 551 transfers the optical signal of a predetermined time slot of the time-division multiplexed optical signal 511 branched from the optical branching/pushing node 501 to the branching device 551.
22, the signal is outputted to the combiner 570 in synchronization with the optical multiplexed frame signal input from the optical frequency divider 540.

As a result, the optical signal from the optical latch circuit 551 is inserted into an empty time slot of the time division multiplexed signal from the optical erasure circuit 560, and the time division multiplexed optical signal 580 is emitted from the optical drop/add node 500. Similarly, the optical drop/add node 501 inserts the optical signal of a predetermined time slot branched from the optical drop/add node 500, and outputs a time division multiplexed optical signal 581. As described above, the optical branch/add nodes 500, 501
The optical branching/adding nodes 500 and 501 branch the optical signal of any time slot of the input time division multiplexed optical signal to the optical drop/add node of the song, and furthermore, the optical drop/add nodes 500 and 501 erase the optical signal of any time slot. to create an empty time slot,
Since optical signals dropped from other optical add/drop nodes can be inserted into these vacant time slots, optical signals in a given time slot can be exchanged between two time-division multiplexed highways. Furthermore, the optical branch/add nodes 500 and 501 can similarly branch the optical signal of a predetermined time slot to the terminals accommodated by each node, and can also insert the optical signal from each terminal. (Problems to be Solved by the Invention) In the conventional optical drop/add node shown in FIG. 5 above,
When branching and adding optical signals, the optical signals are time-division multiplexed, so as the signal speed increases as the degree of time-division multiplexing increases, the optical clock extraction circuit FB530, optical frequency divider 540, and optical latch circuit 550, 551, light erasure times F
! ? 1560 not only required high-speed operation, but also made it difficult to achieve clock cycle and frame synchronization. Furthermore, in the conventional optical drop/add node shown in FIG. 5, since optical signals are time-division multiplexed, when dropping and adding between optical signals having different signal speeds, the optical clock extraction circuit 530, There was a problem in that the control of the optical frequency divider 540, optical latch circuits 550, 551, and optical erase circuit 560 became sloppy. It is an object of the present invention to eliminate such conventional problems, to reduce the operating speed required of an optical device when branching and adding optical signals, and to easily handle optical signals with different signal speeds. The objective is to provide an optical drop/add node that can perform drop/add operations. (Means for Solving the Problems) In order to solve the above-mentioned problems, the optical branch/add node of the present invention has one input end that receives a wavelength multiplexed signal in which light of a plurality of wavelengths is multiplexed, and a first a second output end, when a predetermined control signal is not applied, all the wavelength multiplexed optical signals are outputted from the first output end, and when the control signal is applied, the wavelength multiplexed optical signal is outputted from the first output end; a variable wavelength selection element that outputs only an optical signal of a predetermined wavelength determined by the type of the control signal among the optical signals from the second output end, and outputs optical signals of other wavelengths from the first output end; a wavelength conversion element that converts an optical signal supplied from another to an optical signal having the same wavelength as the wavelength of the optical signal output from the second output end of the variable wavelength selection element; It comprises a combiner that combines the optical signal from the output end and the optical signal from the output end of the wavelength conversion element. Further, the present invention has first and second input terminals that receive a wavelength multiplexed signal in which light of a plurality of wavelengths is multiplexed and other optical signals, and first and second output terminals that are predetermined. If no control signal is applied, all the wavelength-multiplexed optical signals are output from the first output end, and if the control signal is applied, the wavelength-multiplexed optical signal is outputted from the wavelength-multiplexed optical signal to a predetermined amount determined by the type of the control signal. only the optical signal with a wavelength of is output from the second output end, and the optical signal with other wavelengths is output from the first output end,
A variable wavelength selection element outputs an optical signal input from the second input terminal to the first output terminal, and a wavelength of an optical signal supplied from another output terminal is output from the second output terminal of the variable wavelength selection element. a wavelength conversion element that converts the optical signal into an optical signal of the same wavelength as the wavelength of the optical signal to be supplied to the second input terminal of the variable wavelength selection element. (Function) The optical drop/drop node of the present invention branches an optical signal of a predetermined wavelength from an input wavelength-multiplexed optical signal, further converts the optical signal to a predetermined wavelength, and then inserts the optical signal to generate a wavelength-multiplexed optical signal. Therefore, the operating speed required of the optical device can be kept low even when the degree of multiplicity increases, and optical signals with different speeds can be easily branched and inserted. (Example) Next, the present invention will be explained with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention, and the following explanation, like FIG. 5, will be made regarding the case where a predetermined optical signal is exchanged between two highways. The variable wavelength selection element 120 in the optical drop/add node 100 outputs the wavelength-multiplexed optical signal 110 input from the terminal a from the terminal b, and when a control signal is applied, selects a predetermined wavelength from the wavelength-multiplexed optical signal 110. selects an optical signal and branches it from terminal C to the optical drop/add node 101, and outputs the optical signal having a wavelength other than the predetermined wavelength to the combiner 130 from terminal b. The wavelength of the optical signal selected by the variable wavelength selection element 120 can be changed by an applied control signal. In the example shown in FIG. 1, a multiplexed optical signal 1 with wavelengths λ1 to λ4 input from terminal
A variable wavelength selection element 120 from 10 selects an optical signal with a wavelength λ2 according to a control signal corresponding to the wavelength λ2, branches it from a terminal C to an optical drop/add node 101, and selects an optical signal with a wavelength λ1.
．． A multiplexed optical signal of λ and λ is sent from terminal b to the combiner 130. The wavelength conversion element 140 converts the wavelength of the optical signal of wavelength λ1, for example, in the wavelength multiplexed optical signal 111 branched from the optical drop/add node 101 to the variable wavelength selection element 1.
The optical signal is converted into the wavelength λ of the optical signal selected by 20 and output to the combiner 130. In the combiner 130, the multiplexed light of wavelengths λ1, λ, , λ, from the terminal b of the variable wavelength selection element 120 and the wavelength conversion element 14 are combined.
The optical signal of wavelength λ2 from 0 is combined with the optical signal of wavelength λ1~λ
4 multiplexed optical signals 150 are output from the optical drop/add node 100. Similarly, the optical drop/add node 101
The wavelength of the optical signal with the wavelength λ2 branched from the optical drop/add node 100 is converted to λ》 and added, and the wavelength-multiplexed optical signal 1 is added.
51 is emitted. As described above, the optical drop/add nodes 100 and 101 branch optical signals of a predetermined wavelength from input wavelength multiplexed optical signals to other optical drop/add nodes, and then output optical signals of wavelengths other than the predetermined wavelengths that have been branched. Optical signals from other optical drop/add nodes can be added. In addition to the above embodiment, the optical drop/drop/add nodes ioo and toi similarly branch an optical signal of a predetermined wavelength to each terminal, and convert the optical signal from each terminal to a predetermined wavelength. It is also possible to insert it later.

As described above, according to the optical add/drop node according to the first embodiment of the present invention shown in FIG. 1, since a wavelength multiplexed optical signal can be used, the operating speed required of the optical device may be low.

For example, with a signal speed of 100 M b / s and a multiplicity of 12
8, in the conventional optical drop/add node, the optical device needs to operate at 800 Mb/s, whereas in the optical drop/add node of the present invention, the optical device has a signal speed of 100 Mb/s. It should work. Furthermore, since the optical drop/drop/add notebook of the present invention can use wavelength multiplexed optical signals, each wavelength can be used at 100 Mb/s, 50 Mb/s,
It is also possible to branch and insert multiplexed optical signals with different signal speeds such as b/s and 32 Mb/s. FIG. 2 shows a second embodiment of the invention. Again, we will explain the case where a predetermined optical signal is exchanged between two highways. The variable wavelength selection element 220 in the optical add/drop multiplexer node 200 converts the wavelength-multiplexed optical signal 210 input from the terminal a to the terminal b if no control signal is applied.
When a control signal is applied, the wavelength-multiplexed optical signal 2
Select an optical signal of a predetermined wavelength from 10 and send it to terminal C.
The light is emitted from the optical branch and branched to the optical branch/add node 201 . The wavelength of the optical signal selected by the variable wavelength selection element 120 can be changed by a control signal applied to the variable wavelength selection element 120. In the example shown in FIG. 2, the variable wavelength selection element 220 selects the optical signal of wavelength λ2 from the multiplexed optical signal 210 of wavelengths λ1 to λ inputted from terminal a by the control signal corresponding to wavelength λ2, An optical signal with wavelength λ2 is branched from terminal C to optical drop/add node 201. The wavelength conversion element 230 converts wavelength λ3, for example, in the wavelength multiplexed optical signal 211 branched from the optical drop/add node 201.
The wavelength of the optical signal of . The variable wavelength selection element 220 selects the optical signal of wavelength λ2 inputted from terminal d, multiplexes it with the optical signals of wavelengths λ1, λ,, λ, and outputs a multiplexed optical signal of wavelengths λ1 to λ4 to terminal b. It emits from. Therefore, a wavelength multiplexed optical signal 240 is output from the optical drop/add node 200. Similarly, light branching and
The insertion node 201 converts the wavelength of the optical signal of wavelength λ2 branched from the optical drop/add node 200 into wavelength λ3 and inserts it, and outputs a wavelength-multiplexed optical signal 241. As described above, according to the second embodiment of the present invention shown in FIG. 2, it is possible to obtain the same effect as the first embodiment of the present invention shown in FIG. 1 without using a merger. can. FIGS. 3(a) and 3(b) show specific examples of the variable wavelength selection elements 120 to 220 in the embodiments of FIGS. 1 and 2. The optical waveguides 304 and 305 intersect with each other via a separation layer 301 formed on the substrate 300. When surface acoustic waves corresponding to each wavelength are propagated through the surface acoustic wave waveguide 303, the wavelength of the optical signal is selected in the coupling region 302 between the optical waveguides 304 and 305. FIG. 3(a) is a diagram for explaining the operation of the variable wavelength selection element 120 of FIG. 1 and the variable wavelength selection element 220 of FIG. 2.

If a multiplexed optical signal 310 with wavelengths λ1 to λ is input from terminal a of the optical waveguide 304 and a surface acoustic wave is not propagated to the surface acoustic wave waveguide 303 as a control signal, the wavelengths λ1 to λ are input from terminal b of the optical waveguide 304. , the multiplexed optical signal 310 is output as is. On the other hand, when a surface acoustic wave corresponding to the wavelength λ2 is propagated to the surface acoustic wave waveguide 303 as a control signal, only the optical signal with the wavelength λ2 is selected from the wavelength multiplexed optical signal 310 in the coupling region 302, and as a result, the optical waveguide 3
Only the optical signal of wavelength λ1 is output from the terminal C of 05, and the optical signal of wavelength λ1, λ, . A multiplexed optical signal of λ4 is output from terminal b of the optical waveguide 304. By changing the frequency of the surface acoustic wave, it is possible to absorb an optical signal of a different wavelength and output it from the C@ of the optical waveguide 305. Further, FIG. 3(b) shows the variable wavelength selection element 220 of FIG.
This is a diagram for explaining another operation of . Optical waveguide 304
Multiplexed optical signals 320 with wavelengths λ1, λ2, λ》, λ4 are inputted into the terminal a of the optical waveguide 305, and an optical signal 330 with the wavelength λ2 is inputted into the terminal d of the optical waveguide 305, respectively. If a surface acoustic wave is not propagated to the surface acoustic wave waveguide 303 as a control signal, wavelengths λ1, λ2, λ, λ4 will be transmitted from terminal b of the optical waveguide 304.
A multiplexed optical signal 320 of . On the other hand, if a surface acoustic wave corresponding to the wavelength λ2 is selected as a control signal and transmitted to the surface acoustic wave waveguide 303,
In the coupling region 302, only the optical signal with wavelength λ2 from the wavelength multiplexed optical signal 320 is selected and connected to the C of the optical waveguide 305.
At the same time as being output from @, an optical signal 330 with wavelength λ1
are coupled to the optical waveguide 304 and have wavelengths λ1 . λ,. It is multiplexed into ^4 multiplexed optical signals. As a result, from the terminal b of the optical waveguide 304, a multiplexed optical signal consisting of the optical signals of the wavelengths λ1, λ1, λ4 of the wavelength multiplexed optical signal 320 and the optical signal 330 of the wavelength λ2 is output, and the optical waveguide 304
From the terminal C of 5, the wavelength λ2 of the wavelength multiplexed optical signal 320 is
An optical signal is output. Furthermore, by changing the frequency of the surface acoustic wave, optical signals of different wavelengths can be combined. In this way, using the surface acoustic wave as a control signal, an optical signal of a predetermined wavelength is selected from a wavelength multiplexed optical signal depending on whether or not to propagate it, and the optical signals of a predetermined wavelength are multiplexed to perform wavelength division multiplexing. It can output optical signals. FIG. 4 shows the wavelength conversion element 1 in the embodiment of FIGS. 1 and 2.
An example of 40,230 treetops is shown. Input optical signal 40
0 is once converted into an electrical signal 4 by an optical-to-electrical conversion circuit 410.
Converted to 01. The semiconductor laser diode 411 is
The wavelength of the output light is controlled by the applied driving signal, and the wavelength of the input optical signal 400 is converted into the wavelength of the output optical signal 402 by supplying the electric signal 401 as a driving signal to the semiconductor laser diode 411. can do. When converting the wavelength of the input optical signal 400 to a predetermined wavelength, a variable wavelength semiconductor laser diode may be used as the semiconductor laser diode 411. For example, the tunable wavelength semiconductor laser is described in the document ELECTRONICS, April 9, 1987.
The tunable wavelength semiconductor laser disclosed in LETTERS) Vol. 23, Vol. 8, p. 403 can be used. (Effects of the Invention) As explained above, according to the optical drop/add node of the present invention, wavelength multiplexed optical signals can be used, so the operation required of the optical device can be performed at low speed, and optical signals of different speeds can be used. is also possible.

[Brief explanation of drawings]

FIG. 1 is a top view of the first embodiment of the present invention, FIG. 2 is a block diagram of the second embodiment of the present invention, and FIG. 3 is a variable wavelength selection diagram in FIGS. 1 and 2. FIG. 4 is a diagram showing a specific example of the wavelength conversion element in FIGS. 1 and 2, and FIG. 5 is a diagram showing a specific example of the wavelength conversion element in FIGS.
It is a diagram showing an insertion node. 100, 101, 200, 201... Optical drop/add node, 110, 111, 150, 151, 210, 21
1,240,241...Wavelength multiplexed optical signal, 120.2
20... Variable wavelength selection element, 130... Combiner, 1
40,230...Wavelength conversion element, 300...Base,
301... Separation layer, 302... Bonding region, 303...
... surface acoustic wave waveguide, 304.305 ... optical waveguide, 310 ... wavelength multiplexed optical signal, 400 ... input optical signal, 401 ... electrical signal, 402 ... output optical signal,
410... Optical electrical conversion circuit, 411... Semiconductor laser, 500.501... Optical access terminal, 510,
511,580.581... time division optical signal, 520,
521, 522... Brancher, 530... Optical clock extraction circuit, 540... Optical frequency divider, 550, 551...
- Optical latch circuit, 560... Optical erase circuit, 570...
・Merge device.

Claims (2)

[Claims] (1) having one input end for receiving a wavelength multiplexed signal in which light of a plurality of wavelengths is multiplexed, and first and second output ends;
If a predetermined control signal is not applied, all the wavelength multiplexed optical signals are output from the first output end, and if the control signal is applied, the type of the wavelength multiplexed optical signal is changed from the wavelength multiplexed optical signal to the type of the control signal. a variable wavelength selection element that outputs only an optical signal of a predetermined wavelength determined by the above from the second output end, and outputs optical signals of other wavelengths from the first output end, and an optical signal supplied from another. a wavelength conversion element that converts the wavelength into an optical signal having the same wavelength as the wavelength of the optical signal emitted from the second output end of the variable wavelength selection element; and a first wavelength conversion element of the variable wavelength selection element.
An optical branch/add node comprising: a combiner that combines an optical signal from an output end of the wavelength conversion element with an optical signal from an output end of the wavelength conversion element. (2) It has first and second input ends and first and second output ends that receive a wavelength multiplexed signal in which light of a plurality of wavelengths is multiplexed and other optical signals, and has a predetermined control signal. If not applied, all of the wavelength multiplexed optical signals are output from the first output end, and if the control signal is applied, an optical signal of a predetermined wavelength determined by the type of the control signal is output from the wavelength multiplexed optical signal. The optical signals of other wavelengths are outputted from the first output end, and the optical signals input from the second input end are outputted from the first output end. The variable wavelength selection element converts the wavelength of the optical signal supplied from the other device into an optical signal having the same wavelength as the wavelength of the optical signal emitted from the second output end of the variable wavelength selection element. and a wavelength conversion element supplied to the second input end of the optical drop/add node.