JPH03283927A - Optical repeater - Google Patents

Abstract

PURPOSE:To eliminate the need for light reception receiving directly an illuminance power of a semiconductor laser beam source by sending an electric signal monitored through the use of a 2nd light receiving device optically coupled with the monitoring terminal of a photocoupler to a monitoring circuit and also to a driving current control circuit for the semiconductor laser beam source. CONSTITUTION:This optical repeater consists of an input optical fiber 1, a light receiving device 2, a reception transmission electric circuit 3, light source driving circuits 41, 42, a polarized wave optical coupler 6 and a monitoring circuit 11. The optical coupler 6 consists of two LD light sources 51, 52, a prism 10 with a half mirror and a polarization multiplex film vapor-deposited thereto, an optical fiber 9 and a monitoring PD 8. A signal received by the PD 8 is returned to the light source driving circuits 41, 42 to be used for an input signal to a drive current control circuit (APC circuit). On the other hand, the signal is sent to the monitoring circuit 11 for confirming the operation of the LD light sources 51, 52 and for retrieving a fault point.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical repeater for an optical communication system that uses optical fiber as a transmission cable, and more particularly to an optical repeater constituting an optical submarine repeater system.

[Conventional technology]

The optical repeaters that make up the optical submarine repeater system are equipped with a light source hole length function and an optical signal return monitoring function to improve reliability and detect failure points.

An example of a conventional optical repeater will be described with reference to FIG.

The optical signal transmitted through the optical fiber 1 is converted into an electric signal for reproduction by the optical receiver 2 and the electric circuit 3 for reception and transmission, and is converted into an electric signal for reproduction by the light source drive circuits 43 and 44, respectively.
The light sources 51 and 52 (referred to as D) are driven to reproduce the input signal. The polarization type optical coupler 6 includes two LD light sources 51.
52 and a photodiode (hereinafter referred to as PD) for monitoring the operation of the LD light source.
) 8, a polarization combining prism 10 with a half mirror, and a single mode optical fiber 9.

Automatic light output adjustment of LD light sources 51 and 52
power control: APC)
This is performed by monitoring the rear emitted light of the LD element in the LD light source 51.52 with the PD 71.72.

The optical signals reproduced by the LD light sources 51 and 52 are polarized and synthesized by a polarization synthesis prism 10 with a half mirror, and
The light is split into two parts and received by the PD8.

Most of the combined optical signals are guided to optical fiber 9.

On the other hand, the signal received by the PD 8 is connected to a second light receiver 11 optically coupled to the terminal for return monitoring.

Note that FIG. 2 shows two systems, an uplink relay system and a downlink relay system.

[Problem to be solved by the invention]

In the conventional optical repeater described above, the rear emitted light from the LD element of the LD light source is used as an input signal for the monitoring circuit that monitors the operation of the LD light source, so it is difficult to detect changes in the characteristics of the polarization synthesis film in the optical coupler or the LD. This method has the disadvantage of not being able to cope with optical output deterioration caused by element misalignment or the like.

Furthermore, three PDs are used per relay circuit, which poses a problem in terms of cost.

[Means to solve the problem]

The optical repeater of the present invention includes a first light receiver, a receiving/transmitting electric circuit into which a signal from the first light receiver is input, and a semiconductor laser light source into which signals from the receiving and transmitting electric circuit are respectively input. a first semiconductor laser light source driven by the monitoring circuit that monitors the first operation; a monitoring circuit that monitors the second operation; a semiconductor laser light source; an optical coupler having a terminal for coupling light from the semiconductor laser light source to an optical fiber and a monitoring terminal; a terminal for optically coupling light from the semiconductor laser light source and a monitoring terminal; a second photoreceiver optically coupled to the terminal that monitors the operation of the semiconductor laser light source using a terminal; and an output of a monitoring circuit that monitors the operation of the semiconductor laser light source using a signal from the second photoreceiver. Control levels.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In this embodiment, the input optical fiber 1. Light receiver 2, electric circuit for receiving and transmitting 3. Light source drive circuits 41 and 42. Polarized optical coupler6. a second light receiver 11 optically coupled to the terminal;
It consists of The optical coupler 6 connects the two LD light sources 5
1.52, a prism 10 on which a half mirror and a polarization synthesis film are deposited, an optical fiber 9, and a PD 8 for monitoring.
It consists of.

The signal received by the PD 8 is returned to the light source drive circuit 41, 42, and a monitoring circuit (
APC circuit) is used as an input signal.

On the other hand, it is also sent to the second light receiver 11, which is optically coupled to a terminal for checking the operation of the LD light sources 51 and 52 and searching for fault points. The operation of other parts is no different from the operation of the conventional example shown in FIG.

〔Effect of the invention〕

As explained above, the optical repeater of the present invention uses a second light receiver optically coupled to the monitoring terminal of the optical coupler to receive an electrical signal to be monitored using the second light receiver optically coupled to the terminal. Since the light is sent to the device and also to the monitoring circuit that monitors the operation of the semiconductor laser light source, there is no need for a light receiver that directly receives the light emission power of the semiconductor laser light source.

Therefore, one photoreceiver is required for one regenerative repeater circuit, which has the effect of simplifying the circuit and reducing costs.

In addition, since the drive current is controlled by monitoring the power after combining the output lights of two semiconductor laser light sources, changes in the temperature of the semiconductor laser light source, changes in the axis of the optical system over time, and changes in the characteristics of the polarization synthesis film It is also possible to perform control that follows the same conditions as possible, which has the effect of improving short-term and long-term characteristics.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of a conventional optical repeater. 1... Optical fiber, 2... Light receiver, 3
......Electric circuit, 41,42...Light source drive circuit, 51.52...LD light source, 6...
...Optical coupler, 71, 72, 8...PD, 9.
...Optical fiber, lO...Half mirror
Polarization combining prism with polarization, 11... Second light receiver optically coupled to the terminal.

Claims (1)

[Claims] A first light receiver, a receiving and transmitting electric circuit that receives signals from the first light receiver, and first and second drive current control circuits that respectively input signals from the receiving and transmitting electric circuit. , a first semiconductor laser light source driven by the first drive current control circuit, a second semiconductor laser light source driven by the second drive current control circuit, and the first and second semiconductor laser light sources. an optical coupler having a terminal for coupling the light of 1 to an optical fiber and a terminal for monitoring, a second light receiver optically coupled to the terminal for monitoring, and a signal from the second light receiver used to An optical repeater comprising: a monitoring circuit for monitoring operation of a semiconductor laser light source; and controlling output levels of the first and second drive current control circuits based on a signal from the second light receiver.