JPH087332B2 - Method for switching the optical transmission line without interruption - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a non-instantaneous-interruption switching method capable of switching without interruption during switching of an optical transmission line.

<Prior Art> In optical communication, in various cases such as disconnection of an optical fiber line, route change work, and new subscriber construction work, it is necessary to temporarily cut the optical transmission line and perform the work. Get better.

In such a case, if the optical transmission line is completely cut off and the construction takes a long time, communication is interrupted during this period, causing various inconveniences. Therefore, it is desirable that these works be performed without interruption.

As a response to such a request, conventionally, for example,
A method has been proposed in which the switching parts of the two systems of optical transmission lines are orthogonalized and an optical switch composed of an optical control plate having a special reflection function is placed in this orthogonal part to switch the optical transmission lines of both systems without interruption. (Japanese Patent Laid-Open No. 61-132918) <Problems to be solved by the invention> However, in the case of this method, since an optical switch mainly having a mechanical structure is used, the size tends to be large, and the structure is large. However, there is a drawback in that the switching section cannot be made compact because it is complicated.

The present invention has been made in view of such conventional problems, and it is an object of the present invention to provide a non-interruption switching method of an optical transmission line using an extremely small one-chip optical branching / combining device. is there.

<Means for Solving Problems and Actions Thereof> The feature of the present invention is that the switching section of the optical transmission line has at least two waveguides before and after the switching section and each of the routes is provided. An optical branching / combining device with a storage hole formed between the waveguides is installed, and one optical waveguide of each optical branching / combining device is connected to a normal optical transmission line communicating with the main line optical transmission line, Normally, the waveguide of each path in each optical branching / coupling device is put in a non-coupling state by inserting a small piece-shaped switching element made of a low refractive index material into the accommodation hole or leaving it hollow. When switching the optical transmission line, a bypass optical transmission line is connected between the other waveguides of the optical branching / coupling devices, and the waveguide of each route in each optical branching / coupling device is installed in the storage hole. By inserting a switching element in the form of a small piece made of a refractive index material, the connection state is bypassed and the optical transmission line is bypassed. It is a method for switching without interruption of an optical transmission line, which is characterized by switching to an optical transmission line.

That is, it is possible to freely switch the optical transmission line by coupling / uncoupling the one-chip optical branching / coupling device having the waveguide.

<Example> FIGS. 1A to 1C show an example of the present invention.

In the figure, reference numerals 1 and 1 are one-chip type optical branching / coupling devices having two-path waveguides 2a and 2b.
In the central portion adjacent to, a storage hole 4 into which a member made of a low-refractive index material or a high-refractive index material, for example, in the case of a solid, a switching element 3 in the form of a small piece (chip) is detachably (exchangeably) inserted.
When the switching element 3 made of a low refractive index material is put in (inserted into) the storage hole 4 or is left hollow, the optical branching / coupling units 1 and 1 are in the non-coupling state. When the switching element 3 made of a high-refractive index material is put in, the optical branching / coupling devices 1 and 1 are in a coupled state. In other words, by exchanging this switching element 3 in and out,
These optical branching / combining devices 1,1 coupling / uncoupling are controlled.

Then, these optical branching / coupling devices 1 and 1 are installed in advance before and after the switching unit that requires switching of the optical transmission path. Further, between the waveguides 2a, 2a of these optical branching / combining devices 1, 1 is a normal optical transmission which is communicated with the main optical transmission line L ₀ as shown in FIG. 1 (A). Connect the path L ₁ .

Therefore, in a normal state, if the switching element 3 of the low refractive index material is put in the storage hole 4 or is left empty, and the waveguides 2a and 2b of the optical branching / coupling devices 1 and 1 are uncoupled, The optical signal is transmitted from the upper main line optical transmission line L ₀ to the lower main line optical transmission line L ₀ through the normal optical transmission line L _{1 in the} figure, for example.

However, when a failure or trouble transfer is required between the normal optical transmission lines L ₁ , as shown in FIG. 1B, the optical branching / coupling devices 1, 1 are connected between the other waveguides 2b, 2b. Detour optical transmission line L ₂
Connect.

Then, as shown in FIG. 1 (C),
A switching element 3 made of a high-refractive-index material is put in the accommodation hole 4 of the couplers 1 and 1 to couple the waveguides 2a and 2b of the optical branching / combining device. As a result, the optical signal is transmitted in the upper main line optical transmission line in the figure.
From L ₀ through this detour optical transmission line L ₂ below the main optical transmission line
Transmitted to L ₀ .

After that, the normal optical transmission line L ₁ may be removed, and desired construction or repair may be performed.

As described above, in the present invention, the switching is instantaneously performed, and the optical communication is not interrupted for a long time.

The detachable state of the switching element 36 in the present invention is shown in more detail as shown in FIGS. 2 (A) and 2 (B).

The optical branching / combining device 1 used in the present invention has, as a substrate material, for example, Si, quartz glass, optical glass,
Sapphire, LiNbO ₃ , LiTaO ₃ etc. can be used and their waveguide
The formation of 2a and 2b is not particularly limited, but materials such as SiO ₂ —GeO ₂ , SiO ₂ —N, and SiO ₂ —TiO ₂ can be used.

Further, as the low refractive index material as the switching element 3, for example, carbon tetrachloride, ethylene tetrachloride, hexachlorobutadiene, carbon trichloride, carbon dichloride or a mixture thereof is used, and as the high and low refractive index material, acrylic is used. Polymeric polymeric materials such as acid, methacrylic acid or their derivatives, UV-curable epoxy acrylates, thermosetting polymeric materials such as silicone, high refractive index liquid materials such as α-glomonaphthalene, liquid paraffin, etc. can be used. Further, as the material for this switching, in addition to the above solid, a liquid such as a mixed liquid of CCl ₄ + C ₂ HCl ₂ or the like may be used as long as a desired refractive index can be obtained, or glass + matching oil or the like. Combinations of the above can also be used.

In the above description, the waveguide has two paths, but in some cases it is possible to add three paths or the like.

<Experimental example> As shown in FIG. 3, an optical branching / coupling device in which two paths are close to each other in an approximate X shape was prepared.

The base substrate used here is a silicon substrate (Si) 5
Then, on the oxide layer (SiO ₂ ) 6 on the surface of the waveguide 2a, 2 of two paths
b formed.

The dimensions of each part are l ₁ = 17 mm, l ₂ = 5 mm, l ₃ = 0.7
mm, l ₄ = 0.2 mm, l ₅ = 44 μm, l ₆ = 3 mm, l ₇ = 3 mm, l ₈ = 5
mm, l ₉ = 3 mm, l ₁₀ = 3 mm, l ₁₁ = 250 μm, l ₁₂ = 44 μm,
l ₁₃ = 44 μm and l ₁₄ = 7 μm.

In addition to using the optical branching / combining device with this configuration, a mixed liquid of CCl ₄ + C ₂ HCl ₂ is used as the switching material, and its refractive index is slightly higher than the refractive index of 1.474 of the core portions of the waveguides 2a and 2b. When adjusted to 1.476 and filled between the waveguides 2a and 2b, a coupled state was obtained with an extinction ratio of 20 dB at a wavelength of 1.3 μm, and the optical transmission line could be switched.

At this time, the loss of the waveguides 2a and 2b was 0.2 dB, and it was 0.7 dB including the connection loss, which was practically sufficient.

<Effects of the Invention> As is clear from the above description, according to the present invention, switching reliability is high, and the switching unit can be made compact.
Further, it is possible to provide an extremely excellent method for switching the optical transmission path without interruption, which enables easy operation during switching.

[Brief description of drawings]

FIGS. 1 (A) to 1 (C) are explanatory views showing an embodiment of a method for switching the optical transmission line according to the present invention without interruption, and FIGS.
FIG. 3B is a vertical cross-sectional view showing the detachable state of the switching element,
The figure is a schematic perspective view showing an example of a prototype of the optical branching / coupling device. In the figure, 1,1 '.... light branching and coupling device, 2a, 2b ... waveguide, 3 ... lump switching element, 4 ... housing hole, L ₀ ... main optical transmission path, L ₁ ...... Normal optical transmission line, L ₂ ...... Detour optical transmission line,

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Cho Fukuda 1440 Rokuzaki, Sakura-shi, Chiba Fujikura Electric Cable Co., Ltd. Sakura factory (56) References JP-A 61-132918 (JP, A) JP-A 59-228601 ( JP, A)

Claims (1)

[Claims] 1. An optical branching / coupling device having a waveguide of at least two paths before and after a switching section and having a storage hole formed between the waveguides of the paths is installed in a switching section of an optical transmission line, A normal optical transmission line communicating with the main line optical transmission line is connected to one waveguide of each optical branching / coupling device, and the waveguide of each route in each optical branching / coupling device is normally connected to the storage hole. A switching element in the form of a small piece made of a low refractive index material is inserted in or is left in a hollow state to be in a non-coupling state, while at the time of switching the optical transmission line, another waveguide of each of the optical branching / coupling devices. A detour optical transmission line is connected in between, and a waveguide for each path in each optical branching / combining device is inserted into the storage hole by inserting a small piece-shaped switching element consisting of a high-refractive-index chamber into a coupled state. , A method for switching an optical transmission line without interruption, characterized by switching a normal optical transmission line to a bypass optical transmission line