JPH05110511A - Optical wavelength demultiplexing/multiplexing system - Google Patents

Abstract

PURPOSE:To control the output of an optical fiber amplifier so as to be constant in order to compensate the optical output fluctuation of an optical transmitting board in the case the optical fiber amplifier is used for an optical wavelength demuliplexing multiplexing system. CONSTITUTION:The system is constituted so that outputs of the respective optical transmitting boards 1, 2 whose wavelengths are different from each other are monitored by photodetectors 5, 6, respectively, one of them is subjected to optical direct amplification by an optical fiber amplifier 8, the information of the other is sent to gain control circuits 9, 10, and the gain of the optical fiber amplifier 8 is controlled by controlling excitating light sources 11, 12, respectively, and in order to compensate the output fluctuation of the optical transmitting boards 1, 2, the output of the optical fiber amplifier 8 is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wavelength division multiplexing system in the field of optical communications, and more particularly to an optical wavelength division multiplexing system for stabilizing the output of the optical wavelength division multiplexing system using an optical fiber amplifier.

[0002]

2. Description of the Related Art A conventional optical wavelength division multiplexing system is composed of two or more types of optical transmitters having different optical wavelengths, an optical coupler for multiplexing outputs of the respective optical transmitters, and an optical signal synthesized by the optical couplers. This is a configuration having an optical fiber amplifier for amplifying.

[0003]

In this conventional optical wavelength division multiplexing system, when the optical output of each optical transmission board is reduced (deteriorated) by some factor, the optical amplifier does not have an output stabilization control circuit, or In the case where the constant gain control is performed, there is a problem that the optical output power output to the transmission line is reduced by the amount corresponding to the reduction of the optical transmission board.

[0004]

The optical wavelength division multiplexing system according to the present invention has two different optical wavelengths for converting an electrical signal into an optical signal.
A combination of more than one type of optical transmission board, an optical branching unit that branches the optical output of this optical transmission board, a photodetector that monitors the branched output of this optical branching unit, and the other output light of the optical branching unit. The optical coupler that oscillates, the optical fiber amplifier that directly amplifies the output light of this optical coupler, the gain control circuit that controls the output of this optical fiber amplifier to a constant value, the pumping light source, and this pumping light source An excitation light source drive circuit for driving is provided.

[0005]

In the present invention, when the optical fiber amplifier is used in the optical wavelength division multiplexing system, the output of the optical fiber amplifier is controlled to be constant so as to compensate the optical output fluctuation of the optical transmission board.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numerals 1 and 2 denote optical transmitters having different optical wavelengths for converting electrical signals into optical signals, 3 and 4 denote optical branching units for branching the optical outputs of the optical transmitters 1 and 2, 5,
Reference numeral 6 is a photodetector that monitors the respective branched outputs of the optical branching units 3 and 4, and 7 is an optical coupler that multiplexes the other output lights of the optical branching units 3 and 4. Reference numeral 8 is a rare earth-doped optical fiber, and this rare earth-doped optical fiber 8 constitutes an optical fiber amplifier for directly amplifying the output light of the optical coupler 7. Here, the optical coupler 7 and the rare-earth-doped optical fiber 8 constitute an optical multiplex board. Reference numerals 9 and 10 are gain control circuits for controlling the output of the rare-earth-doped optical fiber 8 which is the optical fiber amplifier so as to keep the output constant. 11, 12 are pumping light sources (lasers), 13 and 14 are pumping light sources 11, 12 Are pumping light source driving circuits (laser driving circuits) for driving the WDM couplers, 15 and 16 are WDM couplers, and 17, 18 and 19 are optical fibers.

Next, the operation of the embodiment shown in FIG. 1 will be described. First, an electric signal is converted into an optical signal by the optical transmitters 1 and 2 having two different wavelengths. Then, the optical outputs are branched by the optical branching units 3 and 4, respectively, and one of them is divided into the photodetector 5 and
Each is monitored at 6 and again converted into an electric signal corresponding to the optical output power. Information on the optical output power from the photodetectors 5 and 6 is sent to the gain control circuits 9 and 10, respectively. The other optical outputs of the optical branching units 3 and 4 are combined by the optical coupler 7 via the optical fibers 17 and 18.

Next, the optical signal synthesized by the optical coupler 7 passes through the WDM coupler 15 and the rare earth-doped optical fiber 8
The light is directly amplified by. This rare earth doped optical fiber 8
The optical signal amplified by is transmitted through the WDM coupler 16 and the optical fiber 19 to the transmission line. Further, the gain control circuits 9 and 10 respectively control the driving currents of the pumping light source driving circuits (laser driving circuits) 13 and 14, that is, the outputs of the pumping light sources (lasers) 11 and 12, respectively.
It is configured to control the gain of the rare earth-doped optical fiber 8. By adopting such a configuration, the optical transmitter board 1,
When there is a change in the optical output power of 2, the gain of the rare earth-doped optical fiber (optical fiber amplifier) 8 can be controlled corresponding to the change, and a stable output can always be sent to the transmission line.

[0009]

As described above, according to the present invention, when the optical fiber amplifier is used in the optical wavelength division multiplexing system, the output of the optical fiber amplifier is controlled to be constant so as to compensate the optical output fluctuation of the optical transmission board. Therefore, when the optical output of the optical transmission board fluctuates, the pump light output can be controlled by the gain control circuit, the gain of the rare earth-doped optical fiber can be controlled, and a stable (constant) optical output is always sent to the transmission line. It has the effect of being able to.

[Brief description of drawings]

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

[Explanation of symbols]

 1, 2 Optical transmitter board 3, 4 Optical branching unit 5, 6 Photodetector 7 Optical coupler 8 Rare earth doped optical fiber (optical fiber amplifier) 9, 10 Gain control circuit 11, 12 Pumping light source (laser) 13, 14 Pumping light source Drive circuit (laser drive circuit) 15,16 WDM coupler 17-19 Optical fiber

Claims (1)

[Claims] 1. An optical transmission board of two or more types having different optical wavelengths for converting an electric signal into an optical signal, an optical branching section for branching an optical output of the optical transmission board, and a branching output of the optical branching section. A photodetector, an optical coupler that multiplexes the other output lights of the optical branching unit, an optical fiber amplifier that directly amplifies the output light of this optical coupler, and the output of this optical fiber amplifier to a constant value. An optical wavelength division multiplexing system, comprising: a gain control circuit for controlling so that the pump light source, and a pump light source driving circuit for driving the pump light source.