JPH0653587A - Optical amplifier - Google Patents

Abstract

PURPOSE:To perform a forward excitation operation and a backward excitation operation and to achieve that a preamplifier whose characteristic is better in the forward excitation operation and a booster amplifier whose characteristic is better in the backward excitation operation are used selectively by using one optical amplifier by a method wherein two sets each of lasers for excitation use and drive circuits are provided and they are changed over and operated. CONSTITUTION:When a drive-circuit changeover device 8 receives a changeover signal used to perform a forward excitation operation for a rare earth-doped optical fiber 1 via a changeover-signal input terminal 13, it drives a first drive circuit 4 and excitation light is emitted from a first laser 3 for excitation. Then, a first WDM coupler 2 receives the excitation light, it unites an optical signal from an optical-signal input terminal 11 and the excitation light and outputs them to an optical-signal output terminal 12. When the drive-circuit changeover device 8 receives a changeover signal used to perform a backward excitation operation, it drives a second drive circuit 7, excitation light is emitted from a second laser 6 for excitation, a second WDM coupler 5 unites an optical signal passed through the rare earth-doped optical fiber and the excitation light, and outputs them to the optical-signal output terminal 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used as an optical amplifier using a rare earth-doped optical fiber. The present invention is used for driving an excitation laser. The present invention relates to an optical amplifier having a function of switching between pumping light of forward pumping and pumping light of backward pumping.

[0002]

2. Description of the Related Art Conventionally, as a pumping method for an optical fiber amplifier using a rare earth-doped optical fiber, there is a forward pumping method in which pumping light is injected from the signal input side of the rare earth-doped optical fiber and a backward pumping method in which pumping light is injected from the output side. is there.

Forward pumping is generally S /
N is often used as a preamplifier by being provided in the preceding stage of the optical receiving circuit. On the other hand, backward pumping can be used as a booster amplifier of an optical transmitter because it can obtain a larger output than forward pumping.

[0004]

As described above, the conventional optical amplifier circuit has a problem of lacking versatility because the optical amplifier circuits are individually designed according to the pumping method.

The present invention solves such a problem, and an object of the present invention is to provide an optical amplifier which can have two functions of forward pumping and backward pumping.

[0006]

According to the present invention, a rare earth-doped optical fiber connected between an optical signal input terminal and an optical signal output terminal is supplied with pumping light having a wavelength close to the wavelength of the optical signal to perform optical amplification. In the optical amplifier for performing the above, a first coupler provided between the optical signal input terminal and the input terminal of the optical fiber, and a first pump whose output is connected to a coupling terminal of the first coupler. Laser, a first drive circuit for driving the first excitation laser, a second coupler provided between the output terminal of the optical fiber and the optical signal output terminal, and a second coupler A second pumping laser connected to the coupling terminal of the coupler, a second drive circuit for driving the second pumping laser, and the first drive circuit according to a switching signal given from a switching signal input terminal. Or of the second drive circuit Characterized in that a drive circuit switch for selectively operating the one.

[0007]

When the drive circuit switch receives the forward excitation switching signal, the first drive circuit is driven to emit the excitation light from the first excitation laser, and the first coupler inputs this excitation light. Combine with optical signal. Further, when the drive circuit switch receives the backward excitation switching signal, it drives the second drive circuit to cause the second excitation laser to emit excitation light, and the second coupler outputs the excitation light and the optical fiber. The optical signal that has passed through is multiplexed.

As a result, one optical amplifier can be provided with the functions of forward pumping and backward pumping, and versatility can be enhanced.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the main part of the embodiment of the present invention.

In the embodiment of the present invention, a first wavelength division multiplexing (hereinafter referred to as WDM) coupler 2 provided between an optical signal input terminal 11 and an input terminal of a rare earth-doped optical fiber 1.
A first pumping laser 3 whose output is connected to the coupling terminal of the first WDM coupler 2, a first drive circuit 4 for driving the first pumping laser 3, and a rare earth-doped light A second WDM coupler 5 provided between the output terminal of the fiber 1 and the optical signal output terminal 12, and a second pumping laser 6 connected to the coupling terminal of the second WDM coupler 5.
And a second drive circuit 7 for driving the second excitation laser 6 and the first drive circuit 4 or the second drive circuit 7 according to the switching signal given from the switching signal input terminal 13.
And a drive circuit switch 8 for selecting and operating one of the two.

Next, the operation of the embodiment of the present invention thus constructed will be described.

The drive circuit switching device 8 has a switching signal input terminal 13
When a switching signal for performing forward pumping of the rare earth-doped optical fiber 1 is received from an external control system via the, the first drive circuit 4 is driven according to the signal, and the pumping light is emitted from the first pumping laser 3. Let Then, the first WDM coupler 2
Receives the pumping light, multiplexes the optical signal from the optical signal input terminal 11 with the pumping light, and outputs the multiplexed signal to the optical signal output terminal 12.

When the drive circuit switch 8 receives a switch signal for rearward pumping of the rare earth-doped optical fiber 1 via the switch signal input terminal 13, it drives the second drive circuit 7 in accordance with the signal, Excitation light is emitted from the second excitation laser 6. Next, the second WDM coupler 5 receives the pumping light, multiplexes the optical signal that has passed through the rare earth-doped optical fiber 1 and this pumping light, and outputs the multiplexed signal to the optical signal output terminal 12.

In this way, by operating the drive circuit switching device 8, it is possible to switch between forward excitation and backward excitation. That is, when the first drive circuit 4 is selected, forward excitation can be performed, and when the second drive circuit 7 is selected, backward excitation can be performed.

[0015]

As described above, according to the present invention, 2
A pair of pumping laser and a drive circuit are provided, and forward and backward pumping is possible by switching these operations, and a single optical amplifier has better characteristics in preamplifier and backward pumping. It can be used properly as a booster amplifier with good characteristics. Further, in the case of a preamplifier, the backward pumping laser can be used as a backup, so that it can be used as a backup when the forward pumping laser fails, and in the case of a booster amplifier, on the contrary, the forward pumping laser can be used as a backup. There is an effect such as being able to.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Rare Earth Doped Optical Fiber 2 First WDM Coupler 3 First Excitation Laser 4 First Driving Circuit 5 Second WDM Coupler 6 Second Excitation Laser 7 Second Driving Circuit 8 Driving Circuit Switch 11 Optical Signal input terminal 12 Optical signal output terminal 13 Switching signal input terminal

Claims (1)

[Claims] 1. An optical amplifier for amplifying a rare earth-doped optical fiber connected between an optical signal input terminal and an optical signal output terminal by applying pumping light having a wavelength close to the wavelength of the optical signal to perform optical amplification. A first coupler provided between the signal input terminal and the input terminal of the optical fiber, a first pumping laser whose output is connected to the coupling terminal of the first coupler, and A first drive circuit for driving the pumping laser, a second coupler provided between the output terminal of the optical fiber and the optical signal output terminal, and connected to the coupling terminal of the second coupler A second pumping laser, a second drive circuit for driving the second pumping laser, and a second drive circuit of the first drive circuit or the second drive circuit according to a switching signal given from a switching signal input terminal. Select one to operate Optical amplifier is characterized in that a drive circuit switch.