JP2731068B2 - 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 fiber amplifier generally applied to optical communication, and more particularly to an improvement in the efficiency of a pumping light source and reliability.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a conventional optical fiber amplifier. As shown in the figure, an Er-doped optical fiber 2 serving as an amplification medium has an input optical fiber 1 connected from the front and an output optical fiber 5 connected from the rear. The output optical fiber 5 is provided with the excitation optical coupler 3 and the optical output monitoring optical splitter 4.

The pumping optical coupler 3 is connected to a pumping light coupler 6 and the pumping light coupler 6 is connected to the pumping light coupling fiber 1.
The excitation light sources 8 and 9 are connected in parallel via 0 and 17 respectively. Each excitation light source 8, 9 is connected to a constant current circuit 11, 12, respectively. On the other hand, the optical output monitoring optical splitter 4 is connected to an optical output detection and excitation light control circuit 7, and the optical output detection and excitation light control circuit 7 further includes a constant current circuit 11,1.
2 connected.

Accordingly, the pumping light output from each of the pumping light sources 8 and 9 is coupled by the pumping light coupler 6 and input to the Er-doped optical fiber 2 via the pumping optical coupler 3 to excite and input. When an optical signal enters the Er-doped optical fiber 2 from the optical fiber 1, the optical signal is directly amplified and output to the output optical fiber 5.

Here, the optical output detection and excitation light control circuit 7
In general, the drive current of each of the constant current circuits 11 and 12 is controlled so that the output light detected by the optical output monitoring optical splitter 4 becomes constant. Reference numerals 13 and 14 are reference voltage terminals, 15 and 16 are + power supply terminals, and 18 and 19 are -power supply terminals. The use of a plurality of excitation light sources 8 and 9 in this manner is required when a high output is required or when there is a problem in the reliability of the excitation light sources.

[0006]

However, the above-mentioned optical fiber amplifier has the following disadvantages. (A) Constant current circuits 11 and 12 dedicated to each excitation light source 8 and 9
Is required. (B) The light output detection and excitation light control circuit 7 must separately control each of the excitation light sources 8 and 9 in order to stabilize the light output, and the control is complicated.

(C) Since the plurality of pumping light sources 8 and 9 are separately controlled, a drive current margin for deterioration and temperature fluctuation of the pumping light sources is secured in the driving circuit for each of the pumping light sources 8 and 9. Need to be kept. If the excitation light sources 8 and 9 cannot be used due to failure, the drive current is wasted. The present invention has been made in view of the above prior art,
An object of the present invention is to provide an optical fiber amplifier having a highly reliable and efficient pump power supply.

[0008]

According to a first aspect of the present invention, there is provided a fiber amplifier for exciting an optical fiber serving as an amplifying medium with a plurality of pumping light sources. And a bypass circuit is provided in parallel between each of the excitation light sources and the excitation light source drive circuit.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 2 shows a first embodiment of the present invention. As shown in the figure, in the present embodiment, two pumping light sources (usually a semiconductor laser that performs constant current driving are used) 8 and 9 are connected in series and connected to a common constant current circuit 11. It is configured to be driven. Other configurations are the same as those shown in FIG.

That is, the Er-doped optical fiber 2, which is an amplification medium, has the input optical fiber 1 connected from the front and the output optical fiber 5 connected from the rear. The output optical fiber 5 is provided with the excitation optical coupler 3 and the optical output monitoring optical splitter 4. The pumping optical coupler 3 is connected to a pumping light coupler 6, and the pumping light coupler 6 is connected in parallel to pumping light sources 8 and 9 via pumping light coupling fibers 10 and 17, respectively.

The excitation light sources 8, 9 are connected in series to a common constant current circuit 11. On the other hand, the optical output monitoring optical splitter 4
Is connected to the optical output detection and excitation light control circuit 7, and
The light output detection and excitation light control circuit 7 is connected to the constant current circuit 11.

Accordingly, the pumping light outputted from each of the pumping light sources 8 and 9 is coupled by the pumping light coupler 6 and is inputted to the Er-doped optical fiber 2 via the pumping optical coupler 3 to be pumped and input. When an optical signal enters the Er-doped optical fiber 2 from the optical fiber 1, the optical signal is directly amplified and output to the output optical fiber 5.

At the same time, an optical output detection and excitation light control circuit 7
Controls the drive current of the constant current circuit 11 so that the output light detected by the optical output monitoring optical splitter 4 becomes constant. As described above, according to the present embodiment, since the common constant current circuit 11 is used for the two excitation power supplies 8 and 9, the number of constant current circuits can be reduced as compared with the related art.
Further, there is an advantage that the light output detection and the control by the excitation light control circuit 7 are simplified.

Next, FIG. 3 shows a second embodiment of the present invention. In the present embodiment, in the configuration of FIG.
9, bypass circuits I and II for bypassing the drive current in parallel
Is provided. The bypass circuits I and II are accompanied by control circuits III and V for controlling them. Control circuit III,
Control by V can be easily configured by detecting the voltage between the terminals of the excitation light sources 8 and 9 and the like.

Therefore, according to this embodiment, even when the pumping light source 8 or 9 has an open failure, the driving current flows through the bypass circuit I or II, so that there is an advantage that the driving current can be commonly used.

FIG. 4 shows a third embodiment of the present invention in which the configuration shown in FIG. 3 is further embodied. In this embodiment, Zener diodes V and VI are used as bypass circuits I and II shown in FIG. In this embodiment, the excitation light source has a higher breakdown voltage than the terminal voltage during normal operation,
Zener diodes V and VI whose operating voltage during conduction does not affect the operation of the constant current circuit 11 are used.

Therefore, according to this embodiment, for example, when the pumping light source 9 has an open fault, the voltage between the terminals of the Zener diode V rises and conducts, and the necessary driving current is supplied to the normal and normal pumping light source 8. can do. Also, the excitation light source 9
When a short-circuit fault occurs, the drive current passes as it is and is supplied to the excitation light source 8.

When it becomes necessary to control the excitation power due to deterioration of the excitation light sources 8, 9 or fluctuations in the environmental temperature, the optical output detection and excitation light control circuit 7 controls the common constant current circuit 11. As a result, the required excitation power can be obtained by changing the drive current.

As described above, in this embodiment, a plurality of pumping light sources can be efficiently driven with a minimum driving current, and stable optical amplification characteristics can be obtained even when a catastrophic failure of the pumping light source such as an open short circuit occurs. I can do it.

In the above embodiment, the amplification medium is E
Although the r-doped optical fiber 2 has been used, the present invention is not limited to this, and a medium that is driven by a current and exhibits an amplifying action can be widely used. In the above embodiment, the Zener diodes V and VI are used as the bypass circuits I and II, but elements having the same function can be widely used.

[0021]

As described above in detail with reference to the embodiments, the present invention provides a common drive for a plurality of excitation light sources.
Since the circuit is used, the configuration of the optical fiber amplifier is simplified, and the reduction of the number of pump light source drive circuits simplifies the control of the pump power for a plurality of pump light sources, thereby facilitating the manufacture. Further, since the margin of the pump light source drive circuit can be minimized, the power consumption of the optical fiber amplifier can be reduced. Further, since the bypass circuit is provided, it is possible to cope with both short-circuit failure and open-circuit failure of the excitation light source. Therefore, according to the present invention, an efficient and highly reliable optical fiber amplifier can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional optical fiber amplifier provided with a plurality of pump light sources.

FIG. 2 is a configuration diagram of an optical fiber amplifier according to a first embodiment of the present invention.

FIG. 3 is a configuration diagram of an optical fiber amplifier according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of an optical fiber amplifier according to a third embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 input optical fiber 2 Er-doped optical fiber 3 excitation optical coupler 4 optical output monitoring optical splitter 5 output optical fiber 6 excitation light coupler 7 output light detection and excitation light control circuit 8, 9 excitation light source 10, 17 excitation light Coupling fiber 11, 12 Constant current circuit 13, 14 Reference voltage terminal 15, 16 + Power supply terminal 18, 19-Power supply terminal I, II Bypass circuit III, IV Bypass control circuit V, VI Zener diode

Claims (1)

(57) [Claims] 1. A fiber amplifier for pumping an optical fiber as an amplification medium by a plurality of pumping light sources, wherein the plurality of pumping light sources are connected in series to a common pumping light source driving circuit, and each of the pumping light sources is connected to the pumping light source. An optical fiber amplifier, wherein a bypass circuit is provided in parallel with each of the excitation light sources between the light source drive circuit.