JPH0669171B2 - A method for switching the optical line without interruption in a two-wavelength multiplex communication system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-interruption switching method for an optical line in a two-wavelength multiplex communication system.

"Prior Art" As a two-way two-wavelength multiplex communication system in optical communication,
There is one shown in FIG. 7, which is connected to the working optical line 1 with the multiplexers / demultiplexers 2a and 2b, and the multiplexers / demultiplexers 2a and 2b are provided with photoelectric converters (O / E) 3a, 3b and electric light. The converters (E / O) 4a and 4b are connected.

When the working optical line 1 is switched to the switching optical line 4 in the system shown in FIG. 7, each multiplexer / demultiplexer 2a, 2b as shown in FIG.
Insert the optical switches 5a and 5b in the vicinity of
Switching of the working signal from the working optical line 1 to the switching optical line 4 is performed by operating these optical switches 5a and 5b.

[Problems to be Solved by the Invention] Optical switches currently in practical use are mainly those that physically move an optical fiber, a prism mirror or the like to switch the optical path.

However, the switching speed of such an optical switch is on the order of milliseconds (ms), and if a high speed signal such as 100 Mpbs is to be switched by the optical switch, a part of the signal may be lost.

Therefore, a high-speed optical switch using the electro-optic effect with a switching speed of about 1 ns has been studied at the research level, but this high-speed optical switch has an insertion loss of about 10 dB or more, and therefore such an optical switch is When two pieces are used, the insertion loss becomes so large as to impair practicality.

In view of the above problems, the present invention aims to provide a method capable of switching an optical line without interruption in a two-wavelength multiplex communication system without affecting an existing service.

"Means for Solving Problems" The present invention is characterized by the following means in order to achieve the intended purpose. That is, each four-terminal optical multiplexer / demultiplexer connected to both ends of the working optical line is
A, 12B, wavelengths of two optical signals are λ ₁ , λ ₂ , wavelength λ ₁
14A, wavelength λ ₁ to input the optical signal of
When the photoelectric converter for emitting the optical signal of 15B is 15B, the four-terminal optical multiplexers / demultiplexers 12A and 12B have transmission characteristics for the optical signal of wavelength λ ₁ and reflection characteristics for the optical signal of wavelength λ _2. The four-terminal optical multiplexer / demultiplexer 12B has the electro-optical converter 14A and the other four-terminal optical multiplexer / demultiplexer 12B.
Are respectively connected to, respective four-terminal optical demultiplexer 12A, respectively 12B connected to three terminals or more double-terminated optical demultiplexer and 13A, 13B, the photoelectric for emitting the optical signal of the wavelength lambda ₂ When the converter is 15A and the electro-optical converter for inputting the optical signal of wavelength λ ₂ is 14B,
Both of the multi-terminal optical multiplexers / demultiplexers 13A and 13B have transmission characteristics with respect to the optical signal of wavelength λ ₁ and reflection characteristics with respect to the optical signal of wavelength λ ₂ , and the photoelectric converter 15A has one of the multi-terminals optical multiplexer / demultiplexer. 13A
In addition, the electro-optical converter 14B is connected to the other multi-terminal optical multiplexer / demultiplexer 13B respectively, and the optical signal of wavelength λ ₁ is transferred from the electro-optical converter 14A side to the four-terminal optical multiplexer / demultiplexer 12A, the working optical line, the four-terminal. The optical signal of wavelength λ _{2 is} transmitted from the optical / optical converter 14B side to the optical multiplexer / demultiplexer 12B, the photoelectric converter 15B side, and the multi-terminal optical multiplexer / demultiplexer 13B, the four-terminal optical multiplexer / demultiplexer 12B, the working optical line, the four-terminal. In the optical communication system for transmitting over the optical multiplexer / demultiplexer 12A, the multi-terminal optical multiplexer / demultiplexer 13A, and the photoelectric converter 15A, when switching the working optical line to the switching line, first, to bypass the working optical line The switching line of
Connected over the unused terminals of both four-terminal optical multiplexers / demultiplexers 12A and 12B, and an electro-optical converter for inputting an optical signal of wavelength λ ₁ to the unused terminal of one multi-terminal optical multiplexer / demultiplexer 13A, After connecting the photoelectric converters for emitting the optical signal of wavelength λ _{1 to} the unused terminals of the other multi-terminal optical multiplexer / demultiplexer 13B respectively, the optical signal of wavelength λ ₁ is transmitted from the newly installed electro-optical converter side. Multi-terminal optical multiplexer / demultiplexer 13A, four-terminal optical multiplexer / demultiplexer 12A, switching line, four-terminal optical multiplexer / demultiplexer 12B, multiple-terminal optical multiplexer / demultiplexer 13B, transmitting to the newly installed photoelectric converter side, then , An electro-optical converter for removing the existing electro-optical converter 14A and the existing photoelectric converter 15B from the four-terminal optical multiplexers / demultiplexers 12A, 12B, and for injecting an optical signal of wavelength λ ₂ into these removed parts, A photoelectric converter for emitting the optical signal of λ ₂ is connected to each other, and an optical signal of wavelength λ ₂ is newly installed. Transmission from the electro-optical converter side to the four-terminal optical multiplexer / demultiplexer 12A, the switching line, the four-terminal optical multiplexer / demultiplexer 12B, and the newly installed photoelectric converter side, and then the working optical line is transmitted to both four-terminal optical multiplexer / demultiplexers 12A. , 12B, and the existing photoelectric converter 15A and the existing electro-optical converter 14B are removed from the multi-terminal optical multiplexers / demultiplexers 13A, 13B.

[Examples] Examples of the method of the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a working optical line in a two-wavelength multiplex communication system, 12A and 12B are four-terminal multiplexers / demultiplexers, and 13A and 13B are multi-terminal multiplexers / demultiplexers having three or more terminals.

Referring to FIG. 1, the four-terminal multiplexer / demultiplexer 12A and the multiple-terminal multiplexer / demultiplexer 13A form a set at the left end of the working optical line 11, and the four-terminal multiplexer / demultiplexer 12B and the multiple-terminal multiplexer / demultiplexer are combined. 13B and the 13B form a pair at the right end of the working optical line 11.

Therefore, the 4-terminal multiplexer / demultiplexer 12A and the multi-terminal multiplexer / demultiplexer 1
Set I of 3A, 4 terminal multiplexer / demultiplexer 12B and multiple terminal multiplexer / demultiplexer 1
Each of the 3B sets II has seven or more terminals.

In the above, the four-terminal multiplexer / demultiplexer 12A and the multi-terminal multiplexer / demultiplexer 13A of the group I, and the four-terminal multiplexer / demultiplexer 12B and the multiple-terminal multiplexer / demultiplexer 13B of the group II are these multiplexers / demultiplexers. Of the four-terminal multiplexer / demultiplexer 12A and the multi-terminal multiplexer / demultiplexer 13B are connected to the respective electro-optical converters (E / O) 14A and 14B, respectively. In the four-terminal multiplexer / demultiplexer 12B and the multi-terminal multiplexer / demultiplexer 13A, photoelectric converters (O / E) 15A and 15B are connected to their respective terminals.

Further, the four-terminal multiplexer / demultiplexer 12A, 12B is provided with a working optical line 11 extending over each one of these terminals.

Both of the four-terminal optical multiplexers / demultiplexers 12A and 12B have transmission characteristics with respect to the optical signal of wavelength λ ₁ and reflection characteristics with respect to the optical signal of wavelength λ ₂ , and both of the multi-terminal optical multiplexers / demultiplexers 13A and 13B also have the following characteristics. Wavelength λ ₁
Of the optical signal and the reflection characteristic of the optical signal of wavelength λ ₂ .

In the method of the present invention, line switching is performed as follows in the bidirectional two-wavelength multiplex communication system shown in FIG.

In the sets I and II of both demultiplexers shown in FIG. ₁ , the optical signal of wavelength λ ₁ is transmitted as electro-optical converter 14A → current optical line 11 → photoelectric converter 15B, and wavelength λ 1 is transmitted. _{The two} optical signals are transmitted in the order of electro-optical converter 14B → current optical line 11 → photoelectric converter 15A.

In this case, two or more unused terminals are left in each of the pair I / II of the multiplexer / demultiplexers.

Therefore, when switching the required optical line,
As shown in the figure, an electro-optical converter 16A for wavelength λ ₁ and a photoelectric converter 17B are connected to each one terminal of both multi-terminal multiplexers / demultiplexers 13A, 13B,
The four-terminal multiplexer / demultiplexer 12A, 12B of each multiplexer / demultiplexer pair I, II includes:
A switching optical line 18 for circumventing the working optical line 11 is laid across each of these terminals, and an optical signal of wavelength λ ₁ is passed through the switching optical line 18.

Next, as shown in FIG. 3, a current electro-optical converter for λ ₁ is used.
14A, the photoelectric converter 15B is removed from the four-terminal multiplexer / demultiplexer 12A, 12B, and the four-terminal multiplexer / demultiplexer 12A, 12B in which the respective converters 14A, 15B are removed are replaced with these converters 14A, 15B. λ ₂ photoelectric converter (O / E) 19A, electro-optical converter (E / O) 20B
Is connected, and a signal of λ ₂ is passed through the switching optical line 18.

Then, as shown in FIG. 4, the working λ ₂ photoelectric converter 15A,
After the electro-optical converter 14B and the working optical line 11 are removed and thus the optical line is switched without interruption, the switching optical line is
Predetermined multiplex communication mainly consisting of 18 is performed.

In the above, the current E / O, O / E to new E
It is necessary to switch to / O, O / E, which uses an electric switch capable of high-speed switching, or inserts a branch in the electrical area in advance to form a branch path,
Alternatively, in the optical branching means of FIG. 5, a set of E / O, O /
This can be done by performing a switching operation on E before switching (FIG. 5A), during switching (FIG. 5B), and after switching (FIG. 5C).

Further, when the optical path length difference between the working optical line 11 and the switching optical line 18 is large, it is necessary to measure the signal transit time on both lines to compensate for the optical path length difference. A length difference measurement compensation means can be adopted.

In addition, the multi-terminal multiplexers / demultiplexers 13A and 13B in the above embodiment have λ ₁
We used the one with transmission and λ ₂ deflection, but connect to these E
By changing the arrangement of / O and O / E, λ ₁ deflection and λ ₂ transmission may be performed.

Next, another embodiment of the method of the present invention will be described with reference to FIG.

FIG. 6 shows a unidirectional two-wavelength multiplex communication system. In this system, an electro-optical converter (E / O) 21A is connected to one terminal of a multi-terminal multiplexer / demultiplexer 13A and a multi-terminal multiplexer / demultiplexer 13B is connected. It is different from the above system in that a photoelectric converter (O / E) 22B is connected to one terminal.

The switching pattern of the same-direction two-wavelength multiplex communication system shown in FIG. 6 is basically the same as that of the bidirectional two-wavelength multiplex communication system.

For example, in the system shown in FIG. 6, λ ₁ = 1.2 μm, λ ₂ =
When the Ge detector is used for O / E with 1.3 μm, Ge
The detector is sensitive to both wavelengths λ ₁ and λ ₂ .

In switching O / E in the system of FIG.
Instead of the means shown in FIG. 5, for example, when switching is performed in the electrical area, the unnecessary O / E for λ ₁ can be used as the O / E for λ ₂ for detouring to the switching optical line, and therefore when switching the line. The required O / E number can be reduced by one.

[Advantages of the Invention] As described above, the method of the present invention is used in a two-wavelength multiplex communication system through a four-terminal multiplexer / demultiplexer, a multi-terminal multiplexer / demultiplexer having three or more terminals, an electro-optical converter, a photoelectric converter, and the like. Since the optical line is switched to the switching optical line, there is no problem that the optical line can be switched without interruption without affecting the current service and the insertion loss becomes large.

[Brief description of drawings]

1 to 4 are explanatory views showing an embodiment of the method of the present invention in the order of the steps, and FIGS. 5 (a), (b) and (c) are the electro-optical converters and photoelectric converters used in the above embodiments. Is an explanatory view showing an example of switching to a new electro-optical converter or photoelectric converter, FIG. 6 is an explanatory view showing the main steps of another embodiment of the method of the present invention, FIG. 7 and FIG. 8 are conventional It is explanatory drawing of an example. 11 …… Current optical line 12A, 12B …… Four-terminal multiplexer / demultiplexer 13A, 13B …… Multi-terminal multiplexer / demultiplexer 14A, 14B …… Electronic converter 15A, 15B …… Photoelectric converter 16A …… Electronic converter 18 …… Switching optical line 19A …… Photoelectric converter 20B …… Electronic converter 21A …… Electronic converter 22B …… Photoelectric converter I, II …… Multiplexer set

Claims (2)

[Claims] 1. Four-terminal optical multiplexers / demultiplexers connected to both ends of a working optical line are 12A and 12B, and wavelengths of two optical signals are λ ₁ and λ, respectively.
₂ , an electro-optical converter for inputting an optical signal of wavelength λ ₁
A, a photoelectric converter 15B for emitting an optical signal of wavelength λ ₁
In this case, if the four-terminal optical multiplexer / demultiplexers 12A and 12B have wavelength λ ₁
Has a transmission characteristic with respect to the optical signal of and a reflection characteristic with respect to the optical signal of the wavelength λ ₂ , and the electro-optical converter 14A is connected to one of the four-terminal optical multiplexer / demultiplexers 12A and the photoelectric converter 15B is connected to the other four-terminal optical multiplexer / demultiplexer. The multi-terminal optical multiplexer / demultiplexer having three or more terminals, which are respectively connected to the multiplexers 12B and are respectively connected to the four-terminal optical multiplexers / demultiplexers 12A and 12B, emit optical signals of 13A, 13B and wavelength λ _2. When the photoelectric converter for this is 15A and the electro-optical converter for inputting the optical signal of wavelength λ ₂ is 14B,
Both of the multi-terminal optical multiplexers / demultiplexers 13A and 13B have transmission characteristics with respect to the optical signal of wavelength λ ₁ and reflection characteristics with respect to the optical signal of wavelength λ ₂ , and the photoelectric converter 15A has one of the multi-terminals optical multiplexer / demultiplexer. 13A
In addition, the electro-optical converter 14B is connected to the other multi-terminal optical multiplexer / demultiplexer 13B respectively, and the optical signal of wavelength λ ₁ is transferred from the electro-optical converter 14A side to the four-terminal optical multiplexer / demultiplexer 12A, the working optical line, the four-terminal. The optical signal of wavelength λ _{2 is} transmitted from the optical / optical converter 14B side to the optical multiplexer / demultiplexer 12B, the photoelectric converter 15B side, and the multi-terminal optical multiplexer / demultiplexer 13B, the four-terminal optical multiplexer / demultiplexer 12B, the working optical line, the four-terminal. In the optical communication system for transmitting over the optical multiplexer / demultiplexer 12A, the multi-terminal optical multiplexer / demultiplexer 13A, and the photoelectric converter 15A, when switching the working optical line to the switching line, first, to bypass the working optical line The switching line of
Connected over the unused terminals of both four-terminal optical multiplexers / demultiplexers 12A and 12B, and an electro-optical converter for inputting an optical signal of wavelength λ ₁ to the unused terminal of one multi-terminal optical multiplexer / demultiplexer 13A, After connecting the photoelectric converters for emitting the optical signal of wavelength λ _{1 to} the unused terminals of the other multi-terminal optical multiplexer / demultiplexer 13B respectively, the optical signal of wavelength λ ₁ is transmitted from the newly installed electro-optical converter side. Multi-terminal optical multiplexer / demultiplexer 13A, four-terminal optical multiplexer / demultiplexer 12A, switching line, four-terminal optical multiplexer / demultiplexer 12B, multiple-terminal optical multiplexer / demultiplexer 13B, transmitting to the newly installed photoelectric converter side, then , An electro-optical converter for removing the existing electro-optical converter 14A and the existing photoelectric converter 15B from the four-terminal optical multiplexers / demultiplexers 12A, 12B, and for injecting an optical signal of wavelength λ ₂ into these removed parts, A photoelectric converter for emitting the optical signal of λ ₂ is connected to each other, and an optical signal of wavelength λ ₂ is newly installed. Transmission from the electro-optical converter side to the four-terminal optical multiplexer / demultiplexer 12A, the switching line, the four-terminal optical multiplexer / demultiplexer 12B, and the newly installed photoelectric converter side, and then the working optical line is transmitted to both four-terminal optical multiplexer / demultiplexers 12A. , 12B, and the existing photoelectric converter 15A, the existing electro-optical converter 14B is removed from each multi-terminal optical multiplexer / demultiplexer 13A, 13B, the non-instantaneous optical line in the two-wavelength multiplex communication system. Switching method. 2. A current-use electro-optical converter, a current-use photoelectric converter, and an optical signal merging / branching device and a loop for returning are connected to each other,
The non-interruption switching method of the optical line in the two-wavelength multiplex communication system according to claim 1, wherein these electro-optical converters and photoelectric converters are used for bypass.