JPH07109915B2 - Optical fiber amplifier - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical amplifier for amplifying and outputting an input optical signal as it is, and more particularly to an optical fiber amplifier for amplifying an optical signal by using a rare earth doped fiber.

[0002]

2. Description of the Related Art For example, when amplifying an input optical signal using a rare earth-doped fiber, a plurality of pumping laser diodes are connected to the fiber, and all output levels of these laser diodes are individually set. It is possible to adjust manually.

[0003]

However, it is difficult to obtain a desired result only by adjusting all the laser diodes in the same manner. That is, the excitation laser
If the characteristics of the diodes vary, the desired amplification cannot be obtained.

Therefore, the object of the present invention is to
It is an object of the present invention to provide an optical fiber amplifier capable of obtaining the maximum amplification degree by adjusting each of the diodes independently even if the characteristics of the diodes vary.

[0005]

According to the present invention, a rare earth-doped fiber and n (n is 3 ) connected to the fiber.
An optical fiber amplifier for amplifying an input optical signal as it is and outputting it as (n-1) pumping laser diodes.
Of the laser diodes for pumping, which are respectively connected to the laser diode and control the output level of each of the (n-1) pumping laser diodes to be constant (n-
1) APC circuits, monitor means for monitoring the output of the optical fiber amplifier, and referring to the output of the monitor means, the output level of the remaining one pumping laser diode is output by the optical fiber amplifier. Is controlled so that
And an auxiliary control means for controlling the optical amplifier.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram of an optical fiber amplifier according to an embodiment of the present invention. The optical fiber amplifier of this embodiment includes two polarization-combining WDM couplers 1 and 2, a rare earth-doped fiber 3, four pump laser diodes 4, and a laser diode 4.
It includes 5, 6, and 7.

In FIG. 1, first, the optical input signal input to the input terminal 13 enters the rare earth-doped fiber 3 via the first polarization combining WDM coupler 1. The output of the first pumping laser diode 4 is kept constant by the first APC circuit 9 and enters the rare earth-doped fiber 3 via the first polarization combining WDM coupler 1. The output of the second pumping laser diode 5 is kept constant by the second APC circuit 10 and enters the rare earth-doped fiber 3 via the first polarization combining WDM coupler 1. Further, the output of the third pumping laser diode 6 is kept constant by the third APC circuit 11, and enters the rare earth-doped fiber 3 via the second polarization combining WDM coupler 2. In this way, the optical input signal is amplified and passes through the 10: 1 splitter 8 to the output terminal 1
It is output from 4 as an optical output signal. Here, the first, second and third APC circuits 9, 10 and 11 are collectively referred to as main control means.

The amplified optical signal is partially branched by the 10: 1 branching device 8 and input to the constant output control circuit 12 as a sub control circuit. That is, the 10: 1 branching device 8 functions as a monitoring means for monitoring the output of the optical fiber amplifier.
Then, the output of the fourth laser diode 7 is controlled by the control signal from the constant output control circuit 12. Therefore, the optical output signal output from the output terminal 14 is kept constant.

[0009]

As described above, the optical fiber according to the present invention is used.
The number of fiber amplifiers is (n-1) (n is a positive integer of 3 or more).
Number of pumping laser diodes independent of each other (n
-1) Each excitation is controlled by controlling each by APC circuits.
Even if the characteristics of the active laser diode vary.
Adjust them independently to get maximum amplification and then
The output level of the remaining one pump laser diode
Control to get a constant output from the fiber optic amplifier
Output level like a booster amplifier,
It is especially useful when used at a very high height.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical fiber amplifier according to an embodiment of the present invention.

[Explanation of symbols]

 1 1st polarization combining WDM coupler 2 2nd polarization combining WDM coupler 3 Rare earth doped fiber 4 1st pumping laser diode 5 2nd pumping laser diode 6 3rd pumping laser diode 7 Fourth excitation laser diode 8 10: 1 splitter 9 First APC circuit 10 Second APC circuit 11 Third APC circuit 12 Output constant control circuit 13 Optical input signal 14 Optical output signal

Claims (1)

[Claims] 1. A rare earth-doped fiber and n (n is a positive integer of 3 or more) pumping laser diodes connected to the fiber are included, and an input optical signal is amplified and output as light. An optical fiber amplifier , comprising (n-1) excitations
(N-1) APC circuits each connected to the active laser diode and controlling the output level of each of the (n-1) pumping laser diodes to be constant, and the output of the optical fiber amplifier is monitored. and monitor means, the output of with reference to the output of said monitor means the output level of the remaining one of the pumping laser diode wherein the optical fiber amplifier is constant for
An optical amplifier, characterized in that it comprises a sub-control means for controlling so as to.