JPS59153142A - Monitor system of underwater photo repeater - Google Patents

Abstract

PURPOSE:To make it possible to measure the photo input power and output power of a photo repeater at a remote terminal station, by such simple constitution that the output lights of upward bound and downward bound repeaters are respectively inputted to the up and down repeaters through a photo feedback circuit and the input power informations thereof are transmitted to the terminal station. CONSTITUTION:In measuring photo input power, an optical switch 8 connects a laser diode 7 and an optical fiber 9 by the remote control signal transmitted from a terminal station through an optical fiber 11. In this state, a modulation circuit 6 is turned ON by the remote control signal from the terminal station and the input light inputted from the optical fiber 11 is converted to an electric signal by an avalanche photodiode 1 while said electric signal is modulated in the modulation circuit 6 by the code converted bias voltage of the avalanche photodiode 1. The modulated electric signal is received at a terminal station through optical fibers 9, 10' while converted to a laser signal by a laser diode 7. In measuring photo output power, the modulation circuit 6 is turned OFF and a modulation circuit 6' is turned ON.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for monitoring optical repeaters constituting an optical digital repeater system, and more specifically, the present invention relates to a method for monitoring optical repeaters constituting an optical digital repeater system, and more specifically, the present invention relates to a method for monitoring optical repeaters that constitute an optical digital repeater system, and more specifically, for monitoring optical input power and optical output power of an optical repeater remotely at a terminal station. Regarding the method of measurement.

(Background Art) Once an optical submarine cable system is installed on the ocean floor, it requires a large amount of money to recover from a failure, so it is required to have extremely high reliability. For this reason, each component that makes up the relay system is required to have high reliability, and during and after construction of the system, it is necessary to closely monitor whether the relay system is operating at the level diagram originally designed. is desired. In particular, it is desirable that the optical input power and optical output power of each repeater can be measured remotely at the terminal station. Regarding the measurement of optical input power, as shown in FIG. The main transmission signal is modulated by the modulation circuit 6 using this bias voltage via the code converter 5, and sent to the terminal station via the laser diode (LD) 7, and the terminal station demodulates this signal. Remote measurement is possible. On the other hand, it is difficult to easily and directly measure optical output power.
Ru. Therefore, conventionally, it has been considered to convert the bias current of a laser diode, which is a light emitting element, into a code in the same manner as in the measurement of optical input power shown in FIG. 1, and to send it to a terminal station.

However, since the bias current of the laser diode is not directly related to the optical output power, it is impossible to know the optical output power from this information.

(Objective of the Invention) The present invention has been made by focusing on such conventional problems, and provides a method for remotely measuring the optical input power and optical output power of an optical repeater at a terminal station with a simple configuration. The purpose is to

(Structure and operation of the invention) The present invention will be explained below based on the drawings. 3. FIG. It is for measuring electric power. In the figure, ■ and 1' are avalanche photodiodes which are light receiving elements, and 6 and 6' are modulation circuits.
The avalanche photodiodes 1, 1' are provided in the electrical circuit of the optical repeater, and are created by a bias generation circuit (not shown) such as a DC-'DC converter in response to instructions from the terminal station, as described above. The main transmission signal is modulated (e.g., mark rate modulation) by inputting the bias voltage of Output to laser diode 7.7'.

7. 7' is a laser diode which is a light emitting element; 8 is an optical switch driven by a remote control signal from a terminal station via an optical fiber 11, and connects the laser diode 7 and the optical fiber 9 or the original fiber] 0; is an optical fiber that returns the output light of the laser diode 7 to the avalanche photodiode 1'.

The optical folding circuit is composed of an optical switch 8 and an optical fiber 1o. Here, the optical switch is driven, for example, as follows. Optical repeater reception filter (not shown)
If a code (remote control signal) that repeats the density and density of the mark rate of the digital signal is transmitted from the end station through the optical fiber 11 at a period that matches the tuning frequency of Frequency components are generated.

The optical switch 8 is driven by applying this output to the optical switch 8 via a detection circuit and an amplifier (both not shown). 10.10' is the main output optical fiber,
11 and 11' are main input optical fibers. In addition,
Optical fibers 9 and 11' are bundled and input to an avalanche photodiode 1'.

Next, measurement of optical input power will be explained. The optical switch 8 normally connects the laser diode 7 and the optical fiber 10, and no output light is generated in the optical fiber 9. When measuring optical input power, the optical switch 8 connects the laser diode 7 and the optical fiber 9 in response to a remote control signal from the terminal station via the optical fiber 11. In this state, a remote control signal is sent to the modulation circuit 6 from the terminal station via the optical fiber 11.
is turned on, the input light input from the optical fiber 11 is converted into an electrical signal by the avalanche photodiode 1,
This electric signal is modulated by the modulation circuit 6 using the sign-converted bias voltage of the avalanche photodiode 1.

The modulated electrical signal (input power information) is converted into an optical signal by the laser diode 7, and then connected to the optical fiber 9 and the modulation circuit 6'.
(off state), laser diode 7' and optical fiber 1
It is received by the terminal station via 0'. The optical signal having the optical input power information remotely measured in this way is demodulated at the terminal station and converted into a bias voltage of the avalanche photodiode 1, and it is possible to know the optical input power corresponding to this bias voltage. ·Wear.

Next, measurement of the optical output power of the optical repeater will be explained. When measuring the optical output power, the laser diode 7 and the optical fiber 9 are connected by the optical switch 8, as in the case of measuring the optical input power described above. In this state, from the terminal station to the optical fiber 11
the modulation circuit 6 is turned off by a remote control signal via the
The modulation circuit 6' is turned on, and the output light from the laser diode 7 is converted into an electrical signal by the avalanche photodiode 1' via the optical switch 8 and the optical fiber 9, and this electrical signal is sent to the modulation circuit 6'. Avalanche Hot
It is modulated by the sign-converted bias voltage of diode 1'. The modulated electrical signal is converted into an optical signal by a laser diode 7, and is received at a terminal station via an optical fiber 10'. By calibrating the optical power thus measured with the optical power output from the laser diode 7 to the main optical fiber 10 in advance, the optical output of the repeater can be determined. Calibration here refers to changing the optical power and measuring the frequency, and at this time, changing the temperature and power supply voltage of the optical repeater to obtain several types of characteristic curves.

In this way, the optical input power and optical output power of the optical repeater can be measured remotely. In addition, these measurements are
The signal from the optical fiber 11' is transmitted in a low state.

Although the above description has been made in one direction, the same applies to the opposite direction by providing an optical switch and an optical fiber between the laser diode 7' and the avalanche photodiode 1.

(Effects of the Invention) As explained above, according to the present invention, optical input power and optical output power of a repeater can be remotely measured at a terminal station with a simple configuration, and optical This is highly effective in realizing submarine cables.

[Brief explanation of drawings]

FIG. 1 shows a conventional optical input power and force measuring circuit, and FIG. 2 shows an embodiment of the present invention. 1.1' ・Avalanche photo diode 2...
・・Bias voltage 3・・・・A G C loop 4・
... Bias generation circuit 5 ... Code conversion circuit 6, 6' - Modulation circuit 7, 7' ... Laser diode 8 ... Optical switch 9, 1 ('), [0', 11, 11'・
Optical Fiber Patent Applicant International Telegraph and Telephone Co., Ltd. Patent Application Agent Patent Attorney Megumi Yamamoto −

Claims (1)

[Claims] In an optical repeater that constitutes an optical digital repeater system, an optical return circuit is provided between an uplink transmission line and a downlink transmission line in the optical circuit of the optical repeater, and is controlled by a terminal station via an optical switch. , a modulation circuit that is provided in each of the electric circuits of the two transmission lines and the down transmission line, and that creates input power information of the input light of the optical repeater and transmits it to the terminal station according to instructions from the terminal station. The output light of each uplink and downlink optical repeater is inputted to each downlink and uplink optical repeater via the optical folding circuit, and the optical input power of the input light of the downlink and uplink optical repeater is input to the end. A monitoring method for an optical submarine repeater, characterized in that the modulation circuit transmits input power information to a terminal station according to an instruction from the station.