JPH04236528A - Optical repeater - Google Patents

Abstract

PURPOSE:To send monitor information without use of a modulation circuit implementing fast speed modulation. CONSTITUTION:An inputted optical signal is relayed by a repeater 11 and outputted through a polarized wave controller 13. A monitor control circuit 12 monitors various information of the repeater 11 and outputs the monitor information from a reply signal output terminal 14 as a reply signal to impress the signal to a polarized wave control terminal 15 of the polarized controller 13. The polarized wave controller 13 changes a polarized wave plane of the optical signal through the polarized wave controller 13 in response to the reply signal fed to the polarized wave control terminal 15.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical repeater having a monitoring function, and more particularly to an optical repeater suitable for an optical direct amplification method.

0002

2. Description of the Related Art In recent years, optical communication systems that transmit information using light have been put into practical use. This optical communication system requires an optical relay system to transmit information over long distances. In this optical relay system, in order to search for a fault point, the optical repeater is required to have a monitoring function that monitors the inside of the optical repeater and sends various monitor information to the terminal station. In particular, submarine relay systems require monitoring of service status from the viewpoint of failure prevention and maintenance. However, in optical repeater systems, monitoring lines are generally not installed, so conventional optical repeaters have to transmit various monitor information within the optical repeater to the terminal station. Mark rate modulation is applied to the main signal based on
A method of applying phase modulation was adopted.

0003

[Problem to be Solved by the Invention] However, when modulating the main signal, especially when the main signal is at a high speed exceeding 1 Gb/s, a modulation circuit that performs high-speed modulation is required, and the modulation becomes difficult. The problem is that it becomes difficult.

[0004]Furthermore, recently, an optical repeater using an optical direct amplification method has been proposed, which has the advantage of being simple in configuration and capable of repeating transmission without converting an optical signal into an electrical signal. On the other hand, when modulating using an electric circuit, there is a problem that the advantages of the above-mentioned optical direct amplification method cannot be utilized.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical repeater that can send monitoring information without using a modulation circuit that performs high-speed modulation and is also suitable for the optical direct amplification method.

[0006]

[Means for Solving the Problems] An optical repeater according to the invention as set forth in claim 1 includes a relay means for relaying and outputting an input optical signal, and a monitoring means for monitoring the relay means and outputting monitoring information. and polarization control means for controlling the plane of polarization of the output light of the relay means based on the monitoring information from the monitoring means.

In this optical repeater, the input optical signal is relayed by the repeating means, and the polarization control means controls the plane of polarization based on monitoring information from the monitoring means and outputs it. Monitoring information is transmitted by changes.

In the optical repeater according to the invention set forth in claim 2, the repeating means according to the invention set forth in claim 1 has an optical direct amplifier, and the input optical signal is converted into an electrical signal by the optical direct amplifier. It is relayed as an optical signal without being transmitted.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an optical repeater according to an embodiment of the present invention.

The optical repeater of this embodiment includes a repeater 11 as a repeater means for repeating and outputting an input optical signal, and monitors this repeater 11, and outputs monitoring information from a response signal output terminal 14. Supervisory control circuit 12 that outputs monitor information
and a polarization controller 13 that receives the output light of the repeater 11 and controls the plane of polarization of the output light of the repeater 11 based on a signal applied to a polarization control terminal 15. The output light of this polarization controller 13 is transmitted to the terminal station via an optical fiber. The response signal output terminal 14 of the supervisory control circuit 12 is
It is connected to the polarization control terminal 15 of the polarization controller 13.

The repeater 11 may be a repeater that once converts an input optical signal into an electrical signal and then repeats the signal, or may be a repeater that has an optical direct amplifier that directly amplifies the optical signal. As a repeater that once converts an optical signal into an electrical signal and then relays it, it may be one that has the so-called 3R functions of equalization amplification, retiming, and identification regeneration, or it may be one that does not have the retiming or identification regeneration functions. . Further, as the optical direct amplifier, there are those that utilize a semiconductor laser and those that utilize an optical fiber.

In this embodiment configured as described above, the input optical signal is subjected to processing including at least amplification by the repeater 11, and the main signal is relayed to the polarization controller 13 as an optical signal. is input. In addition, the supervisory control circuit 1
2 monitors various information of the repeater 11, and when transmitting the monitor information to the terminal station, outputs this monitor information as a response signal from the response signal output terminal 14. This response signal is a signal that is modulated by a predetermined modulation method and has a voltage of "H" level or "L" level. This response signal is applied to the polarization control terminal 15 of the polarization controller 13. The polarization controller 13 changes the plane of polarization of the main signal passing through the polarization controller 13 depending on whether the voltage applied to the polarization control terminal 15 is at the "H" level or the "L" level.

FIG. 2 shows the relationship between the waveform of the response signal applied to the polarization control terminal 15 and the polarization plane of the modulated signal, that is, the main signal, whose polarization plane has been modulated in accordance with the response signal. It is an explanatory diagram. As shown in this figure, polarization controller 1
3, the polarization plane of the main signal is polarization plane a when the response signal is at "L" level, and polarization plane b when the response signal is at "H" level. The output light of this polarization controller 13 is transmitted to the terminal station via an optical fiber. The terminal station detects the alternation of the polarization plane of the transmitted main signal and demodulates the response signal.

As described above, according to the present embodiment, the response signal is transmitted by changing the polarization plane of the main signal output from the repeater 11 in accordance with the response signal from the supervisory control circuit 12. A modulation circuit that performs high-speed modulation is not required, and a response signal can be easily transmitted. Furthermore, since modulation is applied to the optical signal, there is no need to convert the optical signal into an electrical signal once, and when an optical direct amplifier is used as the repeater 11, the advantages of the optical direct amplification method can be utilized. .

Generally, the plane of polarization of an optical signal transmitted through an optical fiber transmission line is
Changes due to pressure, vibration, etc. However, since the period of variation in the plane of polarization is several Hz to several kHz, if the plane of polarization is changed at a higher frequency (for example, several MHz) or by changing it according to a certain sign rule, Can be transmitted as a signal.

Further, some polarization controllers change the plane of polarization by mechanically applying pressure or bending, and others use optical crystals. At present, mechanical polarization controllers are advantageous because of their low insertion loss.

[0017]

As described above, according to the invention as set forth in claim 1, monitoring information is controlled by controlling the polarization plane of an optical signal by the polarization control means based on the monitoring information from the monitoring means. Since the information is sent out, there is an effect that the monitoring information can be sent out without using a modulation circuit that performs high-speed modulation.

Further, according to the second aspect of the invention, the optical signal is directly amplified by the optical direct amplifier, and the polarization plane of the optical signal is controlled by the polarization control means to send out the monitoring information. There is no need to convert it into an electrical signal, and monitoring information can be transmitted while taking advantage of the optical direct amplification method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an optical repeater according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the relationship between a response signal waveform and a polarization plane of a modulated signal in the optical repeater of FIG. 1;

[Explanation of symbols]

11 Repeater 12 Monitoring control circuit 13 Polarization controller 14 Response signal output terminal 15 Polarization control terminal

Claims (2)

[Claims] 1. Relay means for relaying and outputting an input optical signal; monitoring means for monitoring this relay means and outputting monitoring information; and based on the monitoring information from this monitoring means, said relay means and polarization control means for controlling the plane of polarization of the output light. 2. The optical repeater according to claim 1, wherein said repeating means includes an optical direct amplifier.