JPH0117616B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention relates to an optical transmission system, and in particular, to optimize the ratio between branching loss and transmission loss of an optical coupler used for adding and dropping optical signals. The present invention relates to an optical transmission system that allows a large number of terminal devices to be placed on one optical repeater, thereby significantly reducing the number of optical repeaters used. Note that in this specification, an optical coupler refers to an optical device that splits and transmits an input optical signal using a half mirror or the like and sends out the signal. Furthermore, an optical repeater refers to an optical device that amplifies an input optical signal, reproduces a waveform, and outputs the resultant signal.

(2) Technical background Optical transmission systems are systems that transmit various types of information using optical transmission lines (mainly optical fiber cables) as transmission media. Then, an optical signal that changes depending on the content of the information is propagated through the transmission path, and the information is transmitted to a terminal device, such as a data processing device, by this optical signal. On the other hand, as an optical signal propagates through an optical transmission path, its energy (light power) gradually weakens, and energy is lost when it passes through an optical device such as a branch point. Therefore, an optical repeater is used as an optical intermediate repeater, a type of amplifier, that amplifies this weakened optical signal to its original size, regenerates the waveform, and sends it out again to the optical transmission line. There are many cases where In addition, in optical transmission systems that arrange and accommodate multiple data processing devices, an optical coupler is installed on the transmission path, which branches an optical signal from the transmission path that transmits information to a predetermined data processing device. inserted into. However, optical repeaters are extremely expensive. Therefore, it is possible to create a data processing device that can handle a single optical repeater by efficiently setting the combined arrangement of optical repeaters and optical couplers, and by setting the branching/transmission ratio of the optical couplers to an appropriate ratio. It is desirable to have an optical transmission system that can increase the number of optical repeaters to be arranged and reduce the number of optical repeaters used.

(3) Prior art and problems Figures 1 to 4 are diagrams for explaining conventional optical transmission systems using optical couplers, with Figure 1 being an explanatory diagram of the first conventional example, and Figure 2 1 is a diagram showing the optical star coupler of FIG. 1, FIG. 3 is an explanatory diagram of a second conventional example, and FIG. 4 is a diagram showing a normal optical coupler.

In FIG. 1, reference numeral 10 indicates an optical transmission line (mainly an optical fiber cable), 11 an optical star coupler, 12 an optical repeater, and 13 a data processing device. Many conventional optical transmission systems using optical couplers use an optical star coupler 11, as in this first conventional example. This light star coupler 1
1 generally includes a large diameter optical fiber 11a and a plurality of ordinary optical fibers 11, as shown in FIG.
Many of them are constructed by bonding together bundles of b, 11'b (for example, diameter 125 μm). however,
This optical star coupler 11 has a large branching/transmission loss (for example, 30 dB), and also has a large diameter optical fiber 1.
The number of optical fibers 11b, 11'b coupled to 1a is physically limited. Therefore, this first
In the conventional system, as shown in FIG. 1, one optical repeater 1 is provided for one data processing device 13.
2 is required, and the number of data processing devices 13 that can be installed is also limited to around 10 at maximum. In other words, an optical network using this method requires the same number of optical repeaters 12 as the number of data processing devices. Therefore, since this first conventional method requires a large number of optical repeaters 12, there are problems in that it is very expensive and its maintenance is very complicated.

In FIG. 3, numerals 10, 12, and 13 indicate an optical transmission line, an optical repeater, and a data processing device, respectively, as in FIG. 1, and 14 indicates an ordinary optical coupler. In this optical coupler 14, as shown in FIG. 4, input light a is split into transmitted light b and branched light c by a half mirror 14a. This branched light c is
It is inserted into the data processing device 13 in FIG. For example, in this second conventional example, the dynamic range of the optical repeater 12 is 40 dB, and the optical coupler 14 is
If the branch loss is set to 13 dB and the transmission loss is set to 2.5 dB, in the transmission system shape (bus shape) as shown in FIG. is necessary. This second conventional method has the advantage that the number of data processing devices 13 can be increased to a desired number by adding more optical repeaters 12; However, there is a problem in that it is needed and still lacks economic efficiency.

(4) Purpose of the Invention In view of the above conventional problems, the purpose of the present invention is to optimize the add-drop ratio of the optical coupler and to improve the shape of the transmission system (the shape of the branched state of the transmission line). By doing so, it is an object of the present invention to provide an optical transmission system that can significantly reduce the number of optical repeaters used and can accommodate a large number of data processing devices.

(5) Structure of the Invention In order to achieve this object, the present invention provides an optical transmission system in which a plurality of terminal devices are coupled by an optical transmission path having an optical coupler and an optical repeater. , one type or two types of optical couplers with the ratio of branching loss and transmission loss set to an optimal value are connected to a single optical repeater in a tree-like arrangement via an optical transmission line, and these optical couplers By connecting a terminal device to each optical coupler for a terminal, a large number of terminal devices can be arranged in a tree-like manner for a single optical repeater, making it possible to significantly reduce the number of optical repeaters used. An optical transmission method is provided.

(6) Embodiments of the invention Hereinafter, embodiments of the invention will be described in detail based on the drawings.

5 and 6 are diagrams for explaining embodiments of the present invention; FIG. 5 is a diagram showing the first embodiment, and FIG. 6 is a diagram showing the second embodiment.

In FIG. 5, the same parts as those shown in FIGS. 1 to 4 are given the same reference numerals. Therefore, reference numeral 10 indicates an optical transmission line (mainly an optical fiber cable), 12 an optical repeater, 13 a data processing device, 14 an ordinary optical coupler, and 15a, 15b, and 15c a branch loss and a transmission line. This shows an optical coupler with the same loss, that is, one-to-one, and 10a shows a U-shaped folded portion of the optical transmission line 10. As shown in the figure, in this example, two
It is constructed by skillfully combining and arranging various types of optical couplers 14 and 15a to 15c, and is used in a U-shaped optical data bus network. still,
In this embodiment, in order to distinguish between two types of optical couplers, the optical couplers 15a to 15c will be referred to as A optical couplers, and the optical coupler 14 will be referred to as B optical coupler. As shown in the figure, in this embodiment, an optical repeater 12
A optical coupler 15a is coupled to the A optical coupler 15a via a transmission line 10, and A optical couplers 15b and 15c are further coupled to each of the branch and transmission transmission lines 10 of the A optical coupler 15a, and these two A optical couplers 15b ,1
Branch and transmission lines 10 taken out from 5c
(4-segment configuration transmission line) B optical coupler 14
are arranged in series, seven each. Terminal branch paths 10b of each of these B optical couplers 14
and the transmission path of each B optical coupler at the final end (the lowest end in FIG. 5).
are combined. Therefore, 8 in 1 segment
A total of 32 data processing devices are arranged in four segments for one optical repeater 12.
In this case, the dynamic range of the optical repeater 12 is set to 40 dB, and the A optical couplers 15a, 15b, 1
The branching and transmission loss of 5c are each 5dB, and B
The branch loss of optical coupler 14 is 13 dB, and the transmission loss is 13 dB.
It is set as 2.5 dB, and is sent out from the optical repeater 12 and connected to the A optical couplers 15a to 15c and each B
The intensity of the light in each transmission line 10 branched and transmitted by the optical coupler 14 is a value corresponding to the value shown in parentheses in the figure, and as described above, the intensity of light in each transmission line 10 is 32 for one optical repeater 12. data processing device 13
can be placed. As described above, in this embodiment, the A optical couplers 15a to 15c are arranged for segment branching to form a transmission line 10 having a dendritic four-segment configuration, and each of these transmission lines 10 is provided with seven B optical couplers. By arranging 14 for data processing devices, 32 (4×8) data processing devices 13 can be branched and arranged in a dendritic configuration as the standard maximum configuration. In FIG. 5, when further installing the data processing device 13, the data processing device 1
3. For example, by arranging an optical repeater 12 in place of the data processing device 13 indicated by reference numeral 13 (D ₁ ), the data processing device 13 can be further installed with a configuration similar to that shown in FIG. Further code 1
It is possible to install optical repeaters 12 in place of the data processing devices 3 (D ₂ ), 13 (D ₃ ), and 13 (D ₄ ), respectively, and to add the data processing device 13 in the same manner as described above.

Next, a second embodiment shown in FIG. 6 will be described. In this figure, the same parts as in the above-mentioned FIG. 5 are given the same reference numerals. Therefore, code 1
Reference numeral 0 indicates an optical transmission line (in this case, the illustration is omitted to a single line), 10a indicates a U-shaped folded portion of the transmission line 10, 12 indicates an optical repeater, 13 indicates a data processing device, and 16a to 13 indicate a data processing device. 16g indicates a branching/transmission type optical coupler in which the branching loss and the transmission loss are 1:1. As shown in the figure, in this embodiment, branching loss and transmission loss are 1:1 for a single optical repeater 12.
It is constructed using only a large number of optical couplers 16a to 16g. That is, in this example,
An optical coupler 16a is coupled to the optical repeater 12 via the optical transmission line 10, and the optical coupler 16a is
Optical coupler 1 is installed in each branch path (2 branch paths) of a.
6b, and in the same manner, optical couplers 16c to 16g are arranged in multiple stages (7 stages in this case) and connected in a tree branch, thereby creating 128 ( ²⁷ ) terminal transmission lines 10b. is obtained. Therefore, by arranging a data processing device 13 on each end of the non-transmission line 10b, it is possible to arrange 128 data processing devices in a tree shape for a single optical repeater 12. be. In this case, please perform a dynamic cleanse of the optical repeater 12.
40dB, and the branching and transmission losses of optical couplers 16a to 16g are each set to 5dB.
It is sent out from the optical repeater 12 and each optical coupler 16a~
The light intensity in each branch transmission line branched and transmitted by 16g is a value corresponding to the numerical value shown in parentheses in the figure. The data processing device can be arranged in the maximum practicable configuration. In this way, according to this embodiment, the ratio of branching loss to transmission loss is 1:1.
By skillfully arranging optical couplers 16a to 16g of the same type for branching the transmission line 10, it is possible to realize an optical transmission system in which a large number of data processing devices can be installed efficiently.

(7) Effects of the Invention As explained in detail above, the optical transmission system of the present invention optimizes the ratio of branching loss and transmission loss, and cleverly arranges the shape of the transmission system (transmission path). By devising and improving the shape of the branch state, etc., a single optical repeater can accommodate a large number of data processing devices, which was not possible in the past, and the number of optical repeaters used can be significantly reduced. There are some great effects.

[Brief explanation of drawings]

1 to 4 are diagrams for explaining conventional optical transmission systems using optical couplers. FIG. 1 is an explanatory diagram of the first conventional example, and FIG. 11, FIG. 3 is an explanatory diagram of the second conventional example, FIG. 4 is an explanatory diagram of the ordinary optical coupler 14 shown in FIG. 3, and FIGS. 5 and 6 are explanatory diagrams of the embodiment of the present invention. FIG. 5 is a diagram showing the first embodiment, and FIG. 6 is a diagram showing the second embodiment. 10... Optical transmission line, 10a... U of transmission line 10
Character folding part, 10b... terminal transmission line (branching line),
12... Optical repeater, 13... Data processing device (terminal device), 14... Optical coupler with different ratio of branch loss and transmission loss (for example, 13 dB vs. 2.5 dB), 15a,
15b, 15c, 16a, 16b, 16c, 16
d, 16e, 16f, 16g... Optical couplers with a 1:1 ratio of branch loss to transmission loss (for example, 5 dB vs.
5dB).

Claims (1)

[Scope of Claims] 1. In an optical transmission system in which a plurality of terminal devices are coupled by an optical transmission path having an optical coupler and an optical repeater, branching loss and transmission loss are 1:1 in a single optical repeater. A branching/transmitting optical coupler is coupled to each of the branching and transmitting transmission lines of the optical coupler, and a one-to-one branching/transmitting optical coupler is coupled to each of the branching and transmitting transmission lines of the optical coupler. A large number of optical couplers with different branching losses and transmission losses are arranged in series on each branching and transmission transmission line taken out from the coupler, and a terminal device is connected to the terminal branching line of each optical coupler arranged in series. An optical transmission system in which a large number of terminal devices are branched into a tree-like arrangement for a single optical repeater. 2 In an optical transmission system in which a plurality of terminal devices are connected by an optical transmission path having an optical coupler and an optical repeater, a branching/transmission type optical system in which branching loss and transmission loss are 1:1 in a single optical repeater is used. couplers, placing an optical coupler of the same type as the optical coupler on each branch transmission line of the optical coupler and a transmission line of the optical coupler, further placing an optical coupler of the same type as the above on each branch transmission line of these optical couplers, Furthermore, by branching out a large number of optical couplers of the same type as described above in a multi-stage and dendritic manner, and connecting terminal equipment to the terminal transmission path of each optical coupler in the final stage, a single optical repeater can be connected. An optical transmission method that allows the deployment of a large number of terminal devices.