JP3658598B2 - Bidirectional wavelength multiplexing optical add / drop device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bidirectional wavelength division multiplexing optical add / drop device and can be applied to, for example, a ring-shaped optical network or a bus-shaped optical network.
[0002]
[Prior art]
In a bi-directional ring optical network, applying the same optical fiber in both directions is easy in terms of cost and flexibility of the network (for example, the installation work of the optical fiber is small). preferable. Also, in a ring-shaped optical network to which the same optical fiber is applied in both directions, it is preferable to use wavelength multiplexed light for transmission because it can easily cope with the number of communication channels.
[0003]
In such a ring-shaped optical network that handles bidirectionality with the same optical fiber or handles wavelength multiplexed light, the bidirectional wavelength multiplexed optical add / drop device is an important component. That is, the corresponding wavelength component light is dropped from the wavelength multiplexed light circulating around the ring optical network to the corresponding optical transmission / reception device, or the predetermined wavelength component light from the corresponding optical transmission / reception device is passed through the ring optical network. Bidirectional wavelength multiplexed optical add / drop devices that add to the circulating wavelength multiplexed light are important components.
[0004]
Various types of bidirectional wavelength multiplexing optical add / drop devices have been proposed (see Non-Patent Document 1 and Non-Patent Document 2).
[0005]
[Non-Patent Document 1]
K. -P. Ho, and S.H. -K. Liaw, “Eight-channel bi-directional WDM add / drop multiplexer.” Electron. Technol. Lett. , Vol. 34, pp. 947-948, 1998
[0006]
[Non-Patent Document 2]
J. et al. Kim, and B.B. Lee, “Bidirectional wavelength add-drop multiplexer using multiport optical cigarculators and fiber Bragg gratings.” IEEE Photon. Technol. Lett. , Vol. 12, pp. 561-563, 2000
[0007]
[Problems to be solved by the invention]
However, various conventional bidirectional wavelength division multiplexing add / drop devices are composed of many optical elements so as to be compatible with wavelength division multiplexed light in both directions, and transmission loss in the add / drop device is large. It was a thing.
[0008]
Therefore, a bidirectional wavelength division multiplexing add / drop device having a simple configuration that can suppress transmission loss and the like is desired.
[0009]
[Means for Solving the Problems]
In order to solve this problem, the present invention drops the wavelength component light allocated to the own node from the wavelength multiplexed light having the forward direction as the transmission direction, and also transmits the wavelength multiplexed light having the reverse direction as the transmission direction to the own node. Drop the wavelength component light allocated to, and add the wavelength component light in the forward direction from the corresponding optical transceiver to the wavelength multiplexed light in the forward direction, and the wavelength in the backward direction from the optical transceiver A bidirectional wavelength multiplexed optical add / drop device for adding component light to wavelength multiplexed light in the reverse direction is configured as follows.
[0010]
That is, the first and second circulators having four terminals A, B, C, and D of the complete circulation type having the same circulation direction are provided, and the A terminal of the first circulator is connected to the node side adjacent in the reverse direction. The A terminal of the second circulator connected to the connected first input / output port is connected to the second input / output port connected to the node side adjacent in the forward direction, and the C terminal of the first circulator. Is connected to the first input / output port connected to the optical transceiver, and the C terminal of the second circulator is connected to the second input / output port connected to the optical transceiver. The B terminal of one circulator and the D terminal of the second circulator are at least one fiber Bragg that reflects the wavelength component light that the node drops from the wavelength multiplexed light transmitted in the forward direction. A first optical transmission line having at least one fiber Bragg diffraction grating that reflects the wavelength component light that the node adds to the wavelength division multiplexed light that is transmitted in the forward direction; The B terminal of the circulator 2 and the D terminal of the first circulator have at least one fiber Bragg grating that reflects the wavelength component light that the node drops from the wavelength multiplexed light transmitted in the reverse direction, and the reverse The wavelength-multiplexed light transmitted in the direction is connected via one optical transmission line having at least one fiber Bragg diffraction grating that reflects the wavelength component light that the node adds.
[0011]
Here, it is preferable that at least a part of the plurality of fiber Bragg diffraction gratings is of a wavelength variable type capable of changing the reflection wavelength.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
(A) First Embodiment Hereinafter, a first embodiment of a bidirectional wavelength division multiplexing add / drop device according to the present invention will be described in detail with reference to the drawings.
[0013]
(A-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing the positioning of the bidirectional wavelength multiplexing optical add / drop device of the first embodiment in a ring optical network.
[0014]
In FIG. 1, the ring-shaped optical network 1 has both clockwise and counterclockwise transmission directions. The ring-shaped optical network 1 includes a plurality of nodes N− (FIG. 1 shows six examples). 1 to N-6 are provided. Two adjacent nodes are connected by one optical transmission line (here, optical fiber) 2-12, ..., 2-61.
[0015]
Each of the nodes N-1,..., N-6 is respectively a bidirectional wavelength division multiplexing optical add / drop device (hereinafter simply referred to as an add / drop device) 10-1,. And optical transceivers 11-1,..., 11-6.
[0016]
Each of the add / drop devices 10-1,..., 10-6 separates (drops) the wavelength component light allocated to the own node from the wavelength multiplexed light circulating in the clockwise direction and the counterclockwise direction. Are provided to the corresponding optical transceivers 11-1,..., 11-6, and other wavelength component light is passed as it is. Each of the add / drop devices 10-1,..., 10-6 transmits the wavelength component light provided from the corresponding optical transceiver 11-1,..., 11-6 in the clockwise direction or the counterclockwise direction. Are multiplexed (added) to the wavelength-division multiplexed light.
[0017]
The add / drop devices 10-1,..., 10-6 and the optical transceivers 11-1,..., 11-6 in each node N-1,. (Here, it is assumed to be an optical fiber).
[0018]
Each of the add / drop devices 10-1,..., 10-6 has the same configuration except for the difference in the assigned wavelength components. FIG. 2 is a block diagram illustrating a configuration of the add / drop device 10 (10-1,..., 10-6) according to the first embodiment.
[0019]
In FIG. 2, the add / drop device 10 of the first embodiment includes two circulators 21 and 22 and four fiber Bragg gratings 31 to 34.
[0020]
Each circulator 21 and 22 is a four-terminal (A, B, C, D) complete circulation type, and the circulation direction is the same (FIG. 2 shows an example in which the circulation direction is clockwise. ing). That is, input light from terminal A is output to terminal B, input light from terminal B is output to terminal C, input light from terminal C is output to terminal D, and input light from terminal D is input to terminal A. Is output.
[0021]
The A terminal of the first circulator 21 is connected to the input / output port Y1 of the optical fiber connected to the node (not shown) adjacent in the clockwise direction, and the A terminal of the second circulator 22 is It is connected to an input / output port Y2 for an optical fiber connected to a node (not shown) adjacent in the counterclockwise direction.
[0022]
Further, the C terminal of the first circulator 21 is connected to the input / output port X1 of the first optical fiber connected to the corresponding optical transmission / reception device (not shown). The C terminal is connected to an input / output port X2 for a second optical fiber connected to a corresponding optical transceiver (not shown).
[0023]
Further, the B terminal of the first circulator 21 and the D terminal of the second circulator 22 are connected via one optical transmission line having fiber Bragg diffraction gratings 31 and 32. The B terminal and the D terminal of the first circulator 21 are connected via one optical transmission line having fiber Bragg diffraction gratings 33 and 34.
[0024]
The reflection wavelength λED of the first fiber Bragg diffraction grating 31 is a wavelength component dropped from its wavelength multiplexed light circulating in the counterclockwise direction to its own node. The reflection wavelength λEA of the second fiber Bragg diffraction grating 32 is a wavelength component that the node adds to the wavelength multiplexed light circulating in the counterclockwise direction. The reflection wavelength λWD of the third fiber Bragg diffraction grating 33 is a wavelength component dropped from the wavelength multiplexed light circulating in the clockwise direction to the own node. The reflection wavelength λWA of the fourth fiber Bragg diffraction grating 34 is a wavelength component that the node adds to the wavelength multiplexed light circulating in the clockwise direction.
[0025]
Although not shown, the optical transceiver (11) receives the wavelength component light (λWA) that the node adds to the wavelength multiplexed light circulating in the clockwise direction to the input / output port X1. Then, the wavelength component light (λEA) added by the own node is incident on the wavelength multiplexed light circulating in the counterclockwise direction to the input / output port X2.
[0026]
(A-2) Operation of the First Embodiment Next, the operation of the add / drop device 10 of the first embodiment will be described with reference to the drawings.
[0027]
First, the operation of dropping wavelength component light (λED) destined for the own node from the wavelength multiplexed light circulating in the counterclockwise direction will be described. FIG. 3 shows an optical path in this case.
[0028]
The wavelength multiplexed light circulating in the counterclockwise direction enters the A terminal of the first circulator 21 from the input / output port Y1 and is output from the B terminal. If the wavelength multiplexed light includes wavelength component light (λED) dropped by the node, only the wavelength component light (λED) is reflected by the first fiber Bragg diffraction grating 31, and other wavelength components are reflected. The light passes through the first fiber Bragg diffraction grating 31 as it is.
[0029]
The wavelength component light (λED) reflected by the first fiber Bragg diffraction grating 31 is incident on the B terminal of the first circulator 21 and output from the C terminal, and is not shown in the drawing via the input / output port X1. It is given to the device 11.
[0030]
On the other hand, the wavelength multiplexed light (other than the dropped wavelength component light) that has passed through the first fiber Bragg diffraction grating 31 also passes through the second fiber Bragg diffraction grating 32 as it is and enters the D terminal of the second circulator 22. Then, it is output from the A terminal and sent out to the next node (not shown) in the counterclockwise direction via the input / output port Y2.
[0031]
If the wavelength-multiplexed light circulating in the counterclockwise direction includes the wavelength component light having the reflection wavelength λEA of the second fiber Bragg diffraction grating 32, the reflection location is different. Are dropped in the same manner as in the case of the wavelength component light (λED).
[0032]
Next, an operation of dropping wavelength component light (λWD) destined for the own node from the wavelength multiplexed light circulating in the clockwise direction will be described. FIG. 4 shows an optical path in this case.
[0033]
The wavelength multiplexed light circulating in the clockwise direction is incident on the A terminal of the second circulator 22 from the input / output port Y2 and output from the B terminal. If the wavelength multiplexed light includes wavelength component light (λWD) dropped by the node, only the wavelength component light (λWD) is reflected by the third fiber Bragg diffraction grating 33, and other wavelength components are reflected. The light passes through the third fiber Bragg diffraction grating 33 as it is.
[0034]
The wavelength component light (λWD) reflected by the third fiber Bragg diffraction grating 33 is incident on the B terminal of the second circulator 22 and output from the C terminal, and is not shown in the figure via the input / output port X2. It is given to the device 11.
[0035]
On the other hand, the wavelength multiplexed light (other than the dropped wavelength component light) that has passed through the third fiber Bragg diffraction grating 33 also passes through the fourth fiber Bragg diffraction grating 34 as it is and enters the D terminal of the first circulator 21. Then, it is outputted from the A terminal and sent out to the next node (not shown) in the clockwise direction via the input / output port Y1.
[0036]
If the wavelength multiplexed light circulating in the clockwise direction includes the wavelength component light having the reflection wavelength λWA of the fourth fiber Bragg diffraction grating 34, the reflection location is different. Dropped in the same manner as in the case of wavelength component light (λWD).
[0037]
Next, an operation of adding wavelength component light (λEA) having the transmission source as a transmission source to the wavelength multiplexed light circulating in the counterclockwise direction will be described. FIG. 5 shows an optical path in this case.
[0038]
The wavelength component light (λEA) added to the wavelength multiplexed light circulating in the clockwise direction enters the input / output port X2 from an optical transmission / reception device (not shown). The wavelength component light (λEA) enters the C terminal of the second circulator 22 and is output from the D terminal. After that, the light is reflected by the second fiber Bragg diffraction grating 32, is incident on the D terminal of the second circulator 22, is output from the A terminal, and the next node (not shown) is counterclockwise through the input / output port Y2. Sent to the.
[0039]
If the wavelength component light having the reflection wavelength λED of the first fiber Bragg diffraction grating 31 is incident on the input / output port X2 from an optical transmission / reception device (not shown), the reflection component is different, but the wavelength component described above is used. Addition is performed in the same manner as in the case of light (λEA).
[0040]
Next, an operation of adding wavelength component light (λWA) having its own node as the transmission source to the wavelength multiplexed light circulating in the clockwise direction will be described. FIG. 6 shows an optical path in this case.
[0041]
The wavelength component light (λWA) added to the wavelength multiplexed light circulating in the clockwise direction enters the input / output port X1 from an optical transmission / reception device (not shown). The wavelength component light (λWA) enters the C terminal of the first circulator 21 and is output from the D terminal. After that, the light is reflected by the fourth fiber Bragg diffraction grating 34, is incident on the D terminal of the first circulator 21, is output from the A terminal, and passes the input / output port Y1 to the next node (not shown) in the clockwise direction. Sent out.
[0042]
If the wavelength component light having the reflection wavelength λWD of the third fiber Bragg diffraction grating 33 is incident on the input / output port X1 from an optical transmission / reception device (not shown), the reflection location differs, but the above-described wavelength component It is added in the same manner as in the case of light (λWA).
[0043]
(A-3) Effects of the First Embodiment According to the first embodiment, both the two circulators and several (four) fiber Bragg diffraction gratings have a simple configuration with a small number of optical elements. A directional wavelength multiplexed optical add / drop device can be realized.
[0044]
Also, since the number of optical elements intervening in add or drop is small, loss during add operation or drop operation can be minimized, and transmission loss of wavelength multiplexed light that simply passes through the node, etc. Can also be suppressed.
[0045]
Further, in the bidirectional wavelength division multiplexing add / drop device of the first embodiment, the path of the wavelength multiplexed light in the counterclockwise direction and the path of the wavelength multiplexed light in the clockwise direction are almost perfectly separated. Therefore, crosstalk between the wavelength multiplexed light in the counterclockwise direction and the wavelength multiplexed light in the clockwise direction can be suppressed.
[0046]
(B) Second Embodiment Next, a second embodiment of the bidirectional wavelength division multiplexing add / drop apparatus according to the present invention will be briefly described with reference to the drawings.
[0047]
FIG. 7 is a block diagram showing the configuration of the add / drop device according to the second embodiment. The same or corresponding parts as those in FIG. 2 according to the first embodiment are indicated by the same reference numerals. Yes.
[0048]
The add / drop device 10A according to the second embodiment includes first and third fiber Bragg diffraction gratings 31 and 33 having a reflected wavelength as a dropped wavelength component, and second and third wavelengths having a reflected wavelength component as a reflected wavelength. The fourth fiber Bragg diffraction gratings 32 and 34 are replaced with variable-wavelength fiber Bragg diffraction gratings 31A to 34A.
[0049]
The variable wavelength fiber Bragg diffraction grating can change the reflection wavelength by, for example, expansion and contraction thereof.
[0050]
The add / drop device 10A according to the second embodiment is configured to detect a wavelength component dropped by the node or a wavelength component added by the node at the time of installation or when changing the allocated wavelength for the drop wavelength or the add wavelength. The reflection wavelength is set for the first to fourth fiber Bragg diffraction gratings 31 to 34 having variable wavelengths.
[0051]
After this setting, the add / drop device 10A of the second embodiment operates in the same manner as the add / drop device 10 of the first embodiment.
[0052]
The add / drop device 10A of the second embodiment can achieve the same effects as those of the first embodiment. In addition to this, there is an effect that a drop wavelength and an add wavelength at each node can be arbitrarily set.
[0053]
(C) Other Embodiments In each of the above embodiments, the wavelength component λED dropped from the wavelength multiplexed light circulating in the counterclockwise direction and the wavelength component λEA added to the wavelength multiplexed light circulating in the counterclockwise direction. Although the relationship was not mentioned, the same wavelength component or different wavelength components may be used.
[0054]
When the wavelength component λED to be dropped and the wavelength component λEA to be added are the same, the first fiber Bragg diffraction grating 31 and the second fiber Bragg diffraction grating 32 are combined to apply one fiber Bragg diffraction grating. Alternatively, the first fiber Bragg diffraction grating 31 and the second fiber Bragg diffraction grating 32 may be provided separately even if the wavelength component λED to be dropped and the wavelength component λEA to be added are the same. The former case is effective when the timing of the add operation and the timing of the drop operation are clearly separated.
[0055]
The relationship between the wavelength component λWD dropped from the wavelength multiplexed light circulating in the clockwise direction and the wavelength component λWA added to the wavelength multiplexed light circulating in the clockwise direction is the same as described above.
[0056]
In each of the above embodiments, one wavelength component is dropped for each cyclic direction, and one wavelength component is added for each cyclic direction. However, the wavelength components are dropped for each cyclic direction. The number of wavelength components and the number of wavelength components to be added are not limited to one.
[0057]
For example, when there are a plurality of wavelength components dropped from the wavelength multiplexed light that circulates counterclockwise, a single optical transmission line between the B terminal of the first circulator 21 and the D terminal of the second circulator 22 is used. A fiber Bragg diffraction grating having each wavelength component as a reflection wavelength may be inserted. Further, for example, when there are a plurality of wavelength components added to the wavelength multiplexed light circulating in the counterclockwise direction, one optical transmission path between the B terminal of the first circulator 21 and the D terminal of the second circulator 22 In addition, a fiber Bragg diffraction grating having each wavelength component as a reflection wavelength may be inserted.
[0058]
The same applies to the clockwise direction when there are a plurality of wavelength components to be dropped or a plurality of wavelength components to be added.
[0059]
Further, the first embodiment shows a case where a fiber Bragg diffraction grating having a fixed reflection wavelength is applied, and the second embodiment shows a case where a fiber Bragg diffraction grating having a variable reflection wavelength is applied. However, a fiber Bragg diffraction grating having a fixed reflection wavelength and a fiber Bragg diffraction grating having a variable reflection wavelength may be mixed and applied.
[0060]
When the bidirectional wavelength division multiplexing add / drop device has an optical amplification function, an optical amplifier (for example, EDFA) may be provided at an appropriate position in the optical transmission path.
[0061]
In the above, the case where the bidirectional wavelength multiplexing optical add / drop device of the present invention is applied to a ring-shaped optical network has been shown. However, the bidirectional wavelength multiplexed optical add / drop device of the present invention is applied to other optical networks. be able to. For example, the bidirectional wavelength division multiplexing add / drop device 10 of the present invention can be applied to a bus-type optical network as shown in FIG. Note that the termination device 12 in FIG. 8 performs termination processing for the bus-like transmission line.
[0062]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a bidirectional wavelength multiplexing optical add / drop device with a simple configuration with a small number of optical elements, such as two circulators and several fiber Bragg diffraction gratings.
[0063]
In addition, since the number of optical elements involved in the add or drop operation is small, the loss during the add operation or the drop operation can be minimized, and the transmission loss of wavelength multiplexed light that simply passes through the node is also reduced. Etc. can also be suppressed.
[0064]
Furthermore, in the bidirectional wavelength-multiplexed optical add / drop device of the present invention, the forward wavelength multiplexed light path and the reverse wavelength multiplexed light path are separated almost completely, so Crosstalk between the wavelength multiplexed light and the wavelength multiplexed light in the reverse direction can be suppressed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a ring-shaped optical network to which a bidirectional wavelength division multiplexing add / drop device of the present invention can be applied.
FIG. 2 is a block diagram showing a configuration of a bidirectional wavelength division multiplexing add / drop device according to the first embodiment.
FIG. 3 is an explanatory diagram of a drop path from wavelength multiplexed light that circulates counterclockwise in the first embodiment;
FIG. 4 is an explanatory diagram of a drop path from wavelength multiplexed light that circulates clockwise according to the first embodiment;
FIG. 5 is an explanatory diagram of an add path to wavelength multiplexed light that circulates counterclockwise according to the first embodiment;
FIG. 6 is an explanatory diagram of an add path to wavelength division multiplexed light that circulates clockwise in the first embodiment;
FIG. 7 is a block diagram showing a configuration of a bidirectional wavelength division multiplexing add / drop device according to a second embodiment.
FIG. 8 is a block diagram showing a configuration example of a bus optical network to which the bidirectional wavelength division multiplexing add / drop device of the present invention can be applied.
[Explanation of symbols]
10, 10A, 10-1 to 10-6 ... bidirectional wavelength division multiplexing optical add / drop device,
11-1 to 11-6: Optical transceiver
21, 22 ... circulator,
31-34 ... Fiber Bragg diffraction grating,
31A to 34A ... variable wavelength fiber Bragg grating,
X1, X2 ... I / O ports with the optical transceiver side,
Y1, Y2: Input / output ports for the network side.

Claims (2)

Drops the wavelength component light allocated to the own node from the wavelength multiplexed light whose transmission direction is the forward direction, and drops the wavelength component light allocated to the node from the wavelength multiplexed light whose transmission direction is the reverse direction, and Add the wavelength component light in the forward direction from the corresponding optical transceiver to the wavelength multiplexed light in the forward direction, and add the wavelength component light in the backward direction from the optical transceiver to the wavelength multiplexed light in the backward direction. In the bidirectional wavelength division multiplexing optical add / drop device,
Comprising first and second circulators having four terminals of completely circulating A, B, C, and D having the same circulation direction;
The A terminal of the first circulator is connected to the first input / output port connected to the adjacent node side in the reverse direction, and the A terminal of the second circulator is connected to the adjacent node side in the forward direction. Connected to the second input / output port,
The C terminal of the first circulator is connected to a first input / output port connected to the optical transceiver, and the C terminal of the second circulator is connected to a second input connected to the optical transceiver. Connected to the output port,
The B terminal of the first circulator and the D terminal of the second circulator are at least one fiber Bragg grating that reflects the wavelength component light that the node drops from the wavelength multiplexed light transmitted in the forward direction, and Connected to the wavelength multiplexed light transmitted in the forward direction through one optical transmission line having at least one fiber Bragg grating that reflects the wavelength component light that the node adds.
The B terminal of the second circulator and the D terminal of the first circulator are at least one fiber Bragg grating that reflects the wavelength component light that the node drops from the wavelength multiplexed light transmitted in the opposite direction, and The wavelength-division multiplexed light transmitted in the reverse direction is connected via one optical transmission line having at least one fiber Bragg diffraction grating that reflects the wavelength component light that the node adds. Bidirectional wavelength multiplexing optical add / drop device. 2. The bidirectional wavelength multiplexing optical add / drop device according to claim 1, wherein at least a part of the plurality of fiber Bragg diffraction gratings is of a wavelength variable type capable of changing a reflection wavelength.

Images