JPS58146149A - Transmitting system of optical loop network - Google Patents

Abstract

PURPOSE:To constitute an optical loop network having simple constitution and high reliability, by using optical signals of different waveforms for communication and by-pass. CONSTITUTION:Each optical terminal station device connected mutually in a loop consists of a demultiplexer 6 separating optical signals from a transmission line with the wavelength, an optical reception section 2, an optical transmission section 7 generating two kinds of wavelength of optical signals, and an optical coupler 5. In the normal operation, the optical transmission section 7 of each terminal station device performs transmission of a light source of a wavelength receivable at the section 2 of the next optical terminal station device. If a failure takes place in a specific optical terminal station device in a loop network, the section 7 of the optical terminal station device of the preceding stage transmits signals from the light source of wavelength different from the normal state. Thus, the optical demultiplexer 6 of the optical terminal station device having a failure by-passes this optical signal and transmits the signal to the next optical terminal station device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical loop network transmission system that bypasses a terminal device in which an abnormality has occurred in an optical receiving section or an optical transmitting section.

A loop network is a communication network in which end station devices are connected in a loop, and is excellent in economy, maintainability, expandability, etc., and is therefore often used as a network form for small-scale communication systems. However, in this loop network, if a failure occurs in any one of the terminal devices making up the loop network, there is a danger that the entire system will go down. Therefore, even in an optical loop network, in order to ensure system reliability, an optical bypass function is required to bypass a terminal device where a failure has occurred.

Conventionally, this optical bypass has been achieved in two ways.

One method is to switch the optical signal path using an optical switch 1, as shown in FIG.

This method is unreliable due to the presence of mechanically moving parts.
There are drawbacks. The other one is the optical splitter 4 as shown in FIG.
In this method, the received optical signal is branched and sent out as an optical bypass signal. In this method, the optical bypass signal exists even during normal operation and becomes an interference wave, so it is necessary to ensure a sufficient level difference with the main signal, or to multiplex the main signal and the bypass signal in a time-division manner to eliminate interference between the two. Countermeasures are necessary.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical loop network transmission system that does not have mechanically moving parts and that allows only optical bypass signals to pass through during normal operation, in order to eliminate the above-mentioned drawbacks.

The optical loop network transmission system of the present invention includes an optical demultiplexer that demultiplexes an optical signal from a transmission path into a signal to be supplied to an optical receiving section and an optical bypass signal based on the difference in wavelength; Optical terminal equipment having an optical transmitter that can selectively transmit light and an optical coupler that combines the optical bypass signal and the optical signal from the optical transmitter and sends it out to a transmission path is coupled in a loop. It is characterized by

FIG. 3 shows an embodiment of the present invention. Each optical terminal device includes an optical demultiplexer 6 that demultiplexes an optical signal from a transmission path into a signal to be supplied to the optical receiving section 2 and an optical bypass signal according to the difference in wavelength;
It is characterized by having an optical transmitter 7 that can select and transmit light of different wavelengths, and an optical coupler 5 that combines the optical bypass signal and the optical signal from the optical transmitter 7 and sends it out to a transmission path. shall be.

The wavelengths of the paths in the normal state and in the optical bypass state are configured to appear inversely for each optical terminal device.

In the figure, under normal conditions, the optical transmitter 7 of each optical terminal equipment transmits using a light source of a wavelength that is received by the optical receiver 2 of the next optical terminal equipment, and at this time, there is no optical bypass signal. If an abnormality occurs in a specific optical terminal station in the optical loop network and you want to bypass that optical terminal station, the optical transmitter 7 of the previous optical terminal station is switched to a light source with a wavelength different from that in normal operation. An optical bypass state can be achieved by switching the switch.

As described above, according to the present invention, there are no mechanically movable parts and no optical bypass signal exists during normal operation, so there is no need for measures to reduce interference with the main signal. Therefore, an optical loop network with a simple configuration and high reliability can be realized.

[Brief explanation of drawings]

1 and 2 are block diagrams showing a conventional example, and FIG. 3 is a block diagram showing an embodiment of the present invention. 1... Optical switch, 2... Optical receiver,
3... Optical transmitter, 4... Optical splitter, 5
...Optical coupler, 6... Optical demultiplexer, 7.
...Optical transmitter.

Claims (1)

[Claims] an optical demultiplexer that branches the optical signal from the transmission line into a signal to be supplied to the optical receiver and an optical bypass signal based on the difference in wavelength;
Loop optical terminal equipment having an optical transmitter that can select and transmit light of different wavelengths, and an optical coupler that combines the optical bypass signal and the optical signal from the optical transmitter and sends it to the transmission path. An optical loop network transmission system that is characterized by being connected in the form of an optical loop.