JPH05235458A - Optical fiber amplifier device - Google Patents

Abstract

PURPOSE:To ensure higher flexibility and higher general-purpose properties by specifying in the form of software feedback algorithm for a monitoring signal of an optical film amplifier using a cental processing unit. CONSTITUTION:A central processing unit 1 estimates monitoring signals entered following a program stored in a memory 2, and issues a control signal 1a to a D/A converter 23 in a feedback manner. Each monitoring signal is hereby converted in to an analog signal which is in turn transmitted to a driver circuit 5. The driver circuit 5 alters the analog signal to a driving current 5a and transmits the same to an excitation laser diode 15 for input of excitation light into an optical fiber 16, further transmitting part of the same to a PD 12 serving as an optical monitor for conversion of the same to an excitation LD module optical monitoring signal 19. The signal 19 is sent into the central processing unit 1 through an A/D converter 22. Hereby, algorithm to generate the control signal 19 from the monitoring signals 17, 18 is determined only by software of the central processing unit. Thus, even the algorithm needs to be altered, only the memory 2 is replaced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber doped with a rare earth element and a pumping LD for sending pumping light to this optical fiber.
The present invention relates to an optical fiber amplifier having an element, a drive circuit that drives the pumping LD element, and a controller that controls the drive circuit.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing an example of the configuration of a conventional optical fiber amplifier. The optical fiber amplifier 6 amplifies an optical signal by injecting the optical output of one pump laser diode module 7 (hereinafter referred to as the pump LD module 7) into the optical fiber 16 doped with a rare earth element. The pumping LD module 7 includes a pumping LD element 15 (indicated by LD in the figure) and a photodiode 12 that monitors the intensity of the LD output monitor light 10 of its output. The output of the optical fiber amplifier 6 is controlled by changing the drive current 5a which is the input of the pumping LD module 7 which is one of the components of the amplifier. The optical fiber amplifier 6 uses an optical monitor 11 composed of a photodiode (PD) to monitor three states of the input monitor light 8, the output monitor light 9, and the LD output monitor light 10 for state monitoring.
Monitored individually by 13 and 12, the monitor signal 3 proportional to the intensity of each monitor light is input to the analog control circuit 14.

The analog control circuit 14 arithmetically processes the three kinds of input monitor signals 3, synthesizes the control signal 14a and sends it back to the drive circuit 5, and the drive circuit 5 outputs the drive signal 5a based on the control signal. It is produced and sent to the excitation LD module 7 to change the intensity of its output light. For example, when it is desired to operate the output of the optical fiber amplifier 6 at a constant level, the control circuit 14 drives the pump LD module 7 via the drive circuit 5 so that the intensity of the optical monitor signal output from the PD 13 becomes constant.
Drive control. Further, when it is desired to operate the optical fiber amplifier 6 with a constant gain, the pumping LD module 7 is operated via the drive circuit 5 so that the ratio of the monitor signal output from the PD 11 and the monitor signal output from the PD 13 becomes constant. Let When it is necessary to keep the optical output of the pump LD module 7 constant, control is performed so that the monitor signal output from the pump LD module 7 becomes constant.

The arithmetic processing in the analog control circuit is constituted by an analog electronic circuit such as an operational amplifier and a transistor, and a feedback algorithm such as calculation such as addition and subtraction of signals and determination of the feedback amount of the monitoring signal to the excitation LD module drive current is hard It is realized as a wear.

[0005]

In the above optical fiber amplifier, since the control signal generating function of the analog control circuit 14 is configured by hardware, it is difficult to change its control method (algorithm). There is a drawback that That is, the relationship between each monitor signal and the feedback control amount to the drive current of the excitation LD module 7 is fixed, and to change this, it is necessary to newly design the hardware. In other words, in the conventional amplification device, it is necessary to design the hardware for each amplification control algorithm, and there is a drawback that its versatility is low.

In order to solve the above-mentioned drawbacks, the present invention provides an optical fiber amplifying device in which the hardware does not have to be changed even if the amplification control algorithm is changed.

[0007]

SUMMARY OF THE INVENTION An optical fiber amplifier according to the present invention monitors and monitors an optical fiber doped with a rare earth element, the intensity of input light to the optical fiber and the intensity of output light from the optical fiber. An optical monitor emitting a signal and injecting controlled excitation light into the optical fiber,
Excitation LD that monitors the intensity of the excitation light and emits a monitor signal
An optical fiber having an optical fiber amplifier including a module, a drive circuit that receives a control signal to controllably drive the excitation LD module, and a control device that processes the emitted monitor signal to generate the control signal In the amplifier device, the control device digitally processes the monitor signal to generate the control signal according to a predetermined algorithm, and a program connected to the central processing device to determine the predetermined generation algorithm. And a storage device for storing.

The present invention also provides the above-mentioned amplifying device,
The pumping LD module is a plurality of pumping LD modules having a maximum value of 4, and these pumping LD modules are
It is more effective if the D module is arranged so that neither the input light side nor the output light side of the optical fiber exceeds two.

Further, in the present invention according to the above invention, when the output of any one of the plurality of pumping LD modules is lowered by some reason, the algorithm changes the driving method of the remaining pumping LD modules. The feature is that the algorithm is prepared in advance to take such measures.

[0010]

The central processing unit of the control device digitally processes the optical monitor signal from the optical monitor of the optical fiber amplifier according to the program stored in the storage device. The excitation LD drive circuit feeds back a control signal as a processing result of the central processing unit to drive the LD of the excitation LD module.

[0011]

1 is a diagram showing the configuration of an embodiment of the present invention. Each monitor signal of the input light monitor signal 17, the output light monitor signal 18, and the pumping LD module light monitor signal 19 is converted into a digital signal by an A / D converter (A / D in the figure) 20 to 22, and is centrally processed. Input to the device 1. The central processing unit 1 arithmetically processes each monitor signal input according to the program stored in the storage device (ROM) 2 and outputs the control signal 1a to the D / A converter 23.
(D / A in the figure) is sent back, converted into an analog signal and sent to the drive circuit 5. The drive circuit 5 converts the input digital feedback signal into a drive current 5a and excites the excitation LD module 7
Pump laser diode (LD) 15. LD15
Is driven to inject the excitation light into the optical fiber 16, and a part of the light is used as a monitor light for the PD 12 which is an optical monitor
Send to. The PD 12 changes this into the pump LD module optical monitor signal 19 described above. This signal 19 is A /
It is inputted to the central processing unit 1 as one of the monitor signals via the D converter 22.

In the above configuration, the algorithm for generating the control signal 1a from the monitor signals 17 to 18 is
It is determined only by the software of the central processing unit 1. Therefore, even when the algorithm needs to be changed, the purpose can be achieved only by replacing the storage device 2 in which the program is stored. Further, since the hardware arithmetic processing of the monitor signal is not required, the configuration of the central processing unit itself becomes extremely simple, and the hardware with high versatility can be realized as a whole.

FIG. 2 is a diagram showing the configuration of another embodiment of the present invention. The optical fiber amplifier 25 is composed of four pumping LD modules 7, 7 ', 26, and 26', and the monitor signals of each are A / D converters 24, 2 respectively.
It is input to the central processing unit 1 through 4 ', 27 and 27'. In addition, the excitation LD modules 7, 7 ', 26, 2
6'is the output of the central processing unit 1 and the D / A converter 2
3, 23 ', 28, 28' and the excitation LD drive circuit 5,
5 ', 29, 29' are independently controlled.

In the above, the two excitation LD modules 7
And 7'are provided for synthesizing polarizations orthogonal to each other, and the pumping LD module 26 and 26 'are also used for the same purpose. The number of these pump LD modules may be one on one side and two on the other side, or two may be provided on one side and not on the other side. Incidentally, it is meaningless to provide three on one side from the viewpoint of the composition mechanism.

When a plurality of pumping LD modules are used as described above, even if the output of some pumping LD modules is lowered for some reason, in the optical fiber amplifier of the present invention, the optical fiber amplifier 25 operates normally. In order to maintain the operation, it is possible to improve the reliability of the optical fiber amplifier by writing in advance a measure such as changing the driving method of the remaining pumping LD module in the program to be used.

In any of the above circuit configurations,
The arrangement order of the D / A converter and the drive circuit may be reversed. However, in that case, since the drive circuit is a digital circuit, the circuit becomes expensive depending on the configuration.

[0017]

As described above, the optical fiber amplifier of the present invention has high flexibility and versatility by using the central processing unit to determine the feedback algorithm of the monitor signal of the optical fiber amplifier by software. Can be realized, and as a result, a high-performance and highly reliable optical fiber amplifier can be obtained.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a block diagram showing an example of a conventional optical fiber amplifier.

[Explanation of symbols]

 1 Central Processing Unit 2 Storage Device 3 Monitor Signal 5, 5'Drive Circuit (Excitation LD Module Drive Circuit) 6 Optical Fiber Amplifier 7, 7'Excitation LD Module 8 Input Monitor Light 9 Output Monitor Light 10 LD Output Monitor Light 11-13 PD (optical monitor) 14 Analog control circuit 15 LD (excitation laser diode) 16 Optical fiber 17 Input light monitor signal 18 Output light monitor signal 19 Excitation LD module optical monitor signal 20-22 A / D (A / D converter) 23, 23 'D / A (D / A converter) 24 to 24' A / D 25 Optical fiber amplifier 26, 26 'Excitation LD module 27 to 27' A / D 28, 28 'D / A 29, 29' Drive circuit

Claims (3)

[Claims] 1. An optical fiber doped with a rare earth element, an optical monitor for monitoring the intensity of input light to the optical fiber and the intensity of output light from the optical fiber and issuing a monitor signal, and the optical fiber controlled by the optical fiber. An optical fiber amplifier including an excitation LD module for injecting the excitation light and emitting a monitor signal by monitoring the intensity of the excitation light; and a drive circuit for receiving the control signal to controllably drive the excitation LD module, In an optical fiber amplifier device having a controller for processing the emitted monitor signal to generate the control signal, the controller digitally processes the monitor signal to process the control signal by a predetermined algorithm. A central processing unit that is generated according to the above, and a storage device that is connected to the central processing unit and that stores a program that defines the predetermined generation algorithm. Optical fiber amplifier characterized in that it comprises a. 2. The pumping LD module is a plurality of pumping LD modules having a maximum value of 4, and the pumping LD modules are provided on either side of the input light side and the output light side of the optical fiber. The optical fiber amplifying device according to claim 1, wherein the optical fiber amplifying device is arranged so as not to exceed two. 3. The algorithm comprises the plurality of excitations L
An optical fiber amplifying device, which is an algorithm in which measures are taken in advance to change the driving method of the remaining pumping LD modules when the output of one of the D modules drops for some reason.