JPH02174430A - Star coupler - Google Patents

Abstract

PURPOSE:To easily detect data collision in a circuit network based on the data transmission state and the reception state of its own station by closing a bus in a matrix coupling from the input port of each optical branching and guide device to an optical synthesis guide device having a corresponding output port. CONSTITUTION:Optical signals of n-set inputted from input ports of n-set of optical branching guide paths 21a-21n are branched respectively in the guide paths 21a-21n, distributed to n-set of the guide paths 21a-21n and outputted. Optical signals outputted from nXn of output ports of the guide paths 21a-21n are inputted to nXn sets of input ports of optical synthesis guide paths 22a-22n. Then optical signals inputted to each input port of the optical synthesis guide paths 22a-22n are subjected to an OR processing in the optical synthesis guide paths 22a-22n respectively and led to the output ports of the optical synthesis guide paths 22a-22n. Thus, optical signals inputted to input ports of all guide paths 21b, 21c, 21n except the guide path 21a in pairs with the output port are subjected to the OR processing and the result is outputted. The signal is subjected to the OR processing similarly as to the other guide paths 22b, 22c, 22n.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is directed to the Carrier 5ense Multi
ple Access with Co11ision
This invention relates to a star coupler that is useful for detecting data collisions in optical signals, which is a problem when constructing an optical star network based on the C5MA/CD (C5MA/CD) method.

(Prior art) Fig. 5 shows data collision of optical signals when a plurality of different signals occur on an optical star network formed using a conventional star coupler as shown in Japanese Patent Publication No. 63-31972, for example. It is a schematic diagram showing a detection method. In the figure,
(1) is a transmission signal line, (2) is a transmitter, (3) is a light emitting element, (4) is a star coupler, (5a), (5b), (5
C), (5n), (6a), (6b), (6C), (6
n) are optical fibers each connected to a star coupler;
(7) is a light receiving element, (8) is an amplifier, (9) is a waveform shaping circuit, (lO) is a receiving signal line, (11) is a delay circuit,
(12) is an exclusive OR circuit, (13) is an integrator circuit, (
14) is a comparator, (15) is a threshold setting terminal, (1
6) is a collision signal line.

Next, the operation will be explained. A transmission signal is input from a transmission signal line (1) to a transmitter (2), and the transmitter (2) drives a light emitting element (3) in response to the transmission signal.

The output of the light emitting element (3) is inputted to the first optical fiber (5a) connected to the input end of the star coupler (4),
Propagate through this optical fiber (5a) and connect to the star coupler (4).
The first optical fiber (6a
), the second optical fiber (6b), the third optical fiber (6c), and the n-th optical fiber (6n), respectively, with equal optical signal power distributed.

The optical signal propagated through the first optical fiber (6a) is inputted to the light receiving element (7) at the same station as the transmitter (2). The light receiving element (7) converts the optical signal into an electrical signal and then outputs it to the amplifier (8). After the amplifier (8) amplifies the signal,
The waveform shaping circuit (9) manually shapes the signal (X) into a rectangular wave and outputs it to the reception signal line (10).

On the other hand, the delay circuit (11) has a delay time equal to the propagation delay time from the manual point of the transmitter (2) to the output point of the waveform shaping circuit (9), and the delay circuit (11) is delayed and output to the exclusive OR circuit (12).

The exclusive OR circuit (12) uses the output of the delay circuit (11) and the signal on the reception signal line (10) as input, and outputs the exclusive OR operation result to the integrating circuit J13). The integrating circuit (13) integrates the output of the exclusive OR circuit (12) and outputs it to the comparator (14). When the integrated value exceeds the determination threshold value, a significant signal is output to the collision display line (16).

Here, the transmission line (transmission line is an optical fiber (5a), (
5b), (5C), (5n), (6a), (6b)
, (6c), (6n) and star coupler (4))
If there is no collision between the local station signal and the other station signal, the local station's transmitted signal delayed by the delay circuit (11) and the local station's received signal output from the waveform shaping circuit (9) match. do. Therefore, the exclusive OR circuit (12) outputs a constant value as the calculation result, and since it does not exceed the judgment threshold set by the threshold setting terminal (15), it is significant for the collision signal line (16). No signal is output.

On the other hand, when the local station signal and the other station signal collide on the transmission path, the local station's transmitted signal delayed by the delay circuit (11) and the local station's received signal output from the waveform shaping circuit (9) does not match. Therefore, the exclusive OR circuit (12) does not output a constant value of zero, and the integral circuit (13) that uses that value manually
) outputs the integration circuit output signal. When the integral circuit output signal exceeds the determination threshold in the comparator (14), a significant signal is output on the collision signal line (16).

[Problem to be solved by the invention]

The conventional signal collision detection method is as described above, so the transmission path is a star coupler (4) and an optical fiber (5a).
), (6a), etc., the delay circuit (11) is required to have a large and accurate delay amount, and the delay circuit (11) is required to transmit the signal without waveform distortion. It has been difficult to satisfy these demands.

The present invention was made to solve these problems, and it is an object of the present invention to provide a star coupler that allows a data transmitting station to easily detect data collisions of optical signals on an optical star network.

[Means to solve the problem]

The star coupler according to the present invention includes n optical branching waveguides each having n output ports for one input port;
n with one output port for n input ports
each output port of the n optical branching waveguides and each input port of the n optical coupling waveguides are coupled in a matrix, and the input port of each optical branching waveguide is connected to the input port of each optical branching waveguide. The path during the matrix coupling to the optical merging waveguide having the output port corresponding to the input cathode is blocked.

(Operation) The star coupler in the present invention branches and combines optical signals so that the transmitted signals from the own station are not returned to the own station, and only the transmitted signals from other stations are received by the own station.

(Example) Hereinafter, an example of the present invention will be explained with reference to the drawings.
The figure is a schematic diagram of the optical branching waveguide (21).

In the figure, (17) is the optical signal input port, (18a)
, (18b), (18c), and (18n) are output ports that branch the optical signal manually inputted from the input port (17) into 0 and output the same.

FIG. 3 is a schematic diagram of the optical merging waveguide (22).

In the figure (19a), (19b), (19c), (1
9n) are input ports for optical signals, and (2o) is an output port that combines 0 optical signals inputted from each of the input ports (19a) to (19n) into one and outputs the same.

FIG. 1 is a schematic diagram of the star coupler (4). In the figure (21a), (21b), (21c), (21n
) is a stack of n optical branching waveguides each having one input port and n output ports, as shown in FIG. 2, (22a), (22b), (22c),
(22n) is a stack of n optical merging waveguides each having one output port for each n input port shown in FIG. input ports are combined in a matrix manner. (23) is composed of n optical branching waveguides (21a) to (2
1n) and all nXn input ports of n optical merging waveguides (22a) to (22n) are coupled in a matrix. However, in the matrix coupling, the bonding surface (23) connects the output ports of the n optical branch waveguides (21a) to (21n) to the input ports of each of the optical branch waveguides (21a) to (21n). The input ports of the paired optical merging waveguides (22a) to (22n) having output ports corresponding to the ports are non-coupled portions (238) (black circles on the bonding surface (23)) that do not couple with each other.
and other optical combining waveguides (22a) to (22n)
) has a coupling portion (23B) (blank on the joint surface (23)) that couples to the input port of the connector (23B).

In the above configuration, n optical branching waveguides (21a) to (
The 0 optical signals input from the input port of 21n) are
The light is branched within each of the branching waveguides (21a) to (2In), and distributed and output to n output ports of each of the branching waveguides (21a) to (21n), respectively. The optical signals output from the nxn output ports of each optical branching waveguide (21a) to (21,n) are transferred from the junction surface (23) to the nxn output ports of each optical combining waveguide (22a) to (22n). It is manually input to the input port. However, due to the matrix coupling configuration on the bonding surface (23), n optical branching waveguides (21a) to (
The optical signal output from the output port of the optical branching waveguides (21a) to (21n) is not input to the input port of the optical branching waveguides (22a) to (22n) that form a pair with each of the branching waveguides (21a) to (21n). Other optical combining waveguides (22a) to 22n except for
) input port manually. Each optical merging waveguide (22a
) to (22n), the optical signals input manually to each input port are as follows:
The respective optical merging waveguides (22a) to (22n) are logically summed, and each of the optical merging waveguides (22a) to (22n)
) is output to the output port.

That is, although a 4-port star network is shown here, for example, an optical signal input from the input port of the optical branching waveguide (21a) is transmitted to the optical combining waveguide (21a) paired with this.
All other optical merging waveguides (22b) except 2a), (
22c) and (22n) are output from the output ports.

In other words, all the optical branching waveguides (21b), (21c), (21n) other than the optical branching waveguide (21a) that forms a pair with the optical combining waveguide (22a) are connected to the output port of the optical combining waveguide (22a).
The optical signals input to the input ports of ) are logically summed and output. Other optical combining waveguides (22b), (22c)
, (22n) are similarly ORed.

FIG. 4 shows an example of an optical signal data collision detection method using the above star coupler. When an optical signal is sent from the transmitter of another station, it is received by the receiver of the own station via the star coupler (4). The received optical signal is passed through an amplifier (
8), and after being shaped into a rectangular wave by a waveform shaping circuit (9), it is output to a reception signal line (10). The received signal that has undergone waveform shaping is also input to the determination circuit (24) at the same time, while the transmission signal on the transmission signal line (1) of the local station is also input to the determination circuit (24). If another station starts transmitting while the own station is transmitting, the determination circuit (24) determines whether the own station's transmission signal line (1
) and the reception signal line (10) of its own station at the same time, and outputs a significant signal to the collision display line (16).

If the local station and the other station do not transmit at the same time, signals will not appear on the local station's transmitting signal line (1) and the local station's receiving signal line (10) at the same time, so the determination circuit (24) determines whether the signal is significant. is not output.

(Effects of the Invention) As described above, according to the star coupler of the present invention, an optical input signal applied from any star coupler input port can be transmitted to all output ports other than the star coupler output port paired with the input port. conversely, optical signals input from all input ports other than the star coupler input paired with the above output port are ORed and output to any star coupler output port. When an optical star network is configured using couplers,
Transmitted signals from the own station are no longer looped back to the own station, and the terminal can easily detect data collisions in the network from the data transmission status and reception status of the own station. There are benefits to be gained.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a star coupler according to an embodiment of the present invention, Fig. 2 is a schematic diagram of an optical branching waveguide constituting the star coupler, and Fig. 3 is a schematic diagram of an optical combining waveguide constituting the star coupler. 4 is a block diagram for explaining the collision detection method when using the star coupler of the present invention, and FIG.
The figure is a block diagram for explaining a collision detection method using a conventional star coupler. In the figure, (21a) to (21n) are optical branching waveguides, (21a) to (21n) are optical branching waveguides, and
2a) to (22n) optical merging waveguides, (23) is a junction surface,
(17), (19a) to (19n) are optical input ports, (
18a) to (18n) and (20) are optical output ports. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] In a star coupler used as a central node when configuring an optical star network, n optical branching waveguides each having n output ports for one input port, and n
n optical merging waveguides each having one output port for each input port, each output port of the n optical branching waveguides and each input port of the n optical merging waveguides. 1. A star coupler comprising: a star coupler which performs matrix coupling, and blocks a path during the matrix coupling from an input port of each optical branching waveguide to an optical merging waveguide having an output port corresponding to the input port.