JPS60254842A - Optical local area network - Google Patents

Abstract

PURPOSE:To decrease the number of optical fibers for wiring and reduce the man-hour of laying work by providing a coupler which has plural input terminals and one output terminal and another coupler which has one input terminal and plural output terminals in each subarea. CONSTITUTION:A coupler 5 with plural input terminals 5a and one output terminal 5b and another coupler 6 with one input terminal 6a and plural output terminals 6b are provided in respective subareas 11-14, and a light signal from the output terminal 1a of each node 1 is transmitted to terminals 5a of the coupler 5 through a optical fiber 3. The coupler 5 multiplexes inputted light signals and outputs the resulting signal to the terminal 5b. The light signal from the terminal 5b of each coupler 5 is transmitted to an input terminal 7a of a star coupler 7 arranged in the subarea 12 through the optical fiber 3. The coupler 7 has output terminals 7b as many as input terminals, and a light signal from a terminal 7b is sent to the terminal 6a of the coupler 6 through optical fiber 3 and demultiplexed by the coupler 6 into light signals, which are sent from output terminals 6b to input terminals 1b of each node 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical local area network, which is one of optical transmission systems.

[Technical background of the invention]

2. Description of the Related Art Conventionally, an optical local area network, which is one type of optical transmission system, has a configuration as shown in FIG. In this optical local area network, subareas 11 , 12 , 13 , and 14 are formed, for example, in units of one building, one floor, etc., and each subarea 11 , 12 , 13 , and 14 has a plurality of Node 1 is installed. Each node 1 in each subarea has an output terminal 1a for transmitting an optical signal,
Optical signals from these output terminals 1a are transmitted via optical fibers 3 to star couplers 2 disposed in predetermined subareas 12. Note that the optical fiber 3 is connected to each subarea 1.
1, 13.

14 and the subarea 12, respectively, to form a cable 4. The star coupler 2 in the sub-area 12 has a plurality of input terminals 2a and the same number of output terminals 2b as the input terminals 2a, and receives optical signals transmitted through the respective optical fibers 3 from the input terminals 2a. At the same time, these optical signals are combined, the combined optical signal is branched, and the branched optical signals are sent to each output terminal 2.
This is what is output from b. The optical signals output from the output terminal 2b of this star coupler 2 are transmitted to each subarea 11, 12, 13, 14 via an optical fiber 3.
is applied to the input terminal 1b of each node 1 of . In addition, in the above explanation, the case where there are four subareas was explained, but
Any number of these subareas are configured in the same way.

[Problems with background technology]

However, in such an optical local area network, a large number of optical fibers are used for wiring connections between each node, which makes installation and handling inconvenient. Star coupler 2 with input terminals was very expensive.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and aims to facilitate installation and handling by reducing the number of optical fiber lines, and to provide an optical local area network at a low cost.

[Summary of the invention]

In the present invention, each of the n subareas is provided with a
a first coupler that combines optical signals input from multiple optical fibers into one optical fiber and sends it out; A second coupler branches the signal into a plurality of optical fibers and sends it out, and the optical signals of the n optical fibers output from each of the first couplers in the subarea are inputted and combined. and a third coupler that branches the optical fibers into n optical fibers and sends them out to each of the second couplers in the subarea.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows an embodiment of the optical local area network of the present invention. Note that in FIG. 2, parts similar to those in the apparatus shown in FIG. 1 are designated by common reference numerals, and explanations thereof will be omitted.

In this embodiment, each subarea 11, 12, 13,
14 are provided with couplers 5 and 6, one each, the coupler 5 having a plurality of input terminals 5a1 and one output terminal 5b, and the coupler 6 having one input terminal 5a.

It has a plurality of output terminals 6b. Each sub area 11
, 12 , 13 , and 14 , the output terminal 1 a of each node 1 is connected to the input terminal 5 a of each coupler 5 via an optical fiber 3 , and the optical signal output from each node 1 is transmitted via the optical fiber 3 . It is transmitted to each coupler 5. When each coupler 5 receives these optical signals, it combines these optical signals and outputs the combined optical signal to the output terminal 5b. The output terminal 5b of each coupler 5 is connected to the input terminal 7 of a star coupler 7 disposed in the subarea 12 via an optical fiber 3.
a, and the respective output terminals 5b
The optical signal sent to the input terminal 7a of the star coupler 7
transmitted to. Note that the optical fiber 3 is connected to the subarea 11
, 13, 14 and the subarea 120, respectively, to form a cable 4. The star coupler 7 has a plurality of input terminals 7a and the same number of output terminals 7 as the input terminals 7a.
When these optical signals are input, these optical signals are combined, and the combined optical signal is split into 6
output to terminal 7b. Each output terminal 7b of the star coupler 7 is connected to each subarea 11 via an optical fiber 3.
゜Input terminal 6a of each coupler 6 of 12, 13, 14
The optical signal output to each output terminal 7b is transmitted to the input terminal 6a of each coupler 6 via an optical fiber. When each coupler 6 receives this optical signal, it branches this optical signal to its respective output terminal 6.
Output to b. Each output terminal 6b of the coupler 6 is connected to the input terminal 1b of each node 1 via the optical fiber 3, and the optical signal output to each output terminal 6b is sent to each node 1 via the optical fiber 3. transmitted.

By the way, as is clear in this embodiment, the number of optical fibers required for connection between each node is only 2n, where l is the number of nodes, which can be significantly reduced compared to the conventional example shown in FIG. can.

Although this embodiment shows the case of four subareas, the present invention is not limited to this, and the same effect can be achieved by providing couplers 5 and 6 in each subarea, regardless of the number of subareas. Can be configured.

In addition, in the optical local area network of this embodiment, an active coupler (converts an input optical signal to an electrical signal, amplifies this electrical signal, converts it to an optical signal, and outputs it) or an optical relay However, by using these, it can be applied to geographically distant sub-areas.

〔Effect of the invention〕

As explained above, according to the present invention, the number of optical fiber wires and the number of star coupler terminals can be reduced, making installation and handling easier.
Furthermore, the cost of optical local area networks will also be lower.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a conventional optical local area network, and FIG. 2 is a diagram for explaining an embodiment of the optical local area network of the present invention. 1... Node, 2... Star coupler, 3... Optical fiber +, 4... Cable, 5.6... Coupler, 7... Star coupler, 11, 12, 13,
14...Sub area. Representative Patent Attorney Norichika Norifue (1 idiot)

Claims (1)

[Claims] a first coupler disposed in each of the n subareas, which combines optical signals input from a plurality of optical fibers into one optical fiber and sends the resultant signal; and a first coupler disposed in each of the n subareas; a second coupler that splits an optical signal input from one optical fiber into a plurality of optical fibers and sends it out; It is characterized by comprising at least a third coupler that inputs signals, combines them, branches them into n optical fibers, and sends them out to each of the second couplers in the sub-areas. Optical local area network.