JP3132464B2 - Optical repeater - 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 repeater, and more particularly, to an optical repeater capable of reducing a supply current in an optical repeater system operated by constant current driving.

[0002]

2. Description of the Related Art FIG. 3 shows an optical fiber transmission system using a conventional optical repeater. This optical fiber transmission system comprises terminal equipment 13a, 13b, transmission optical fiber 15
a, 15b, 15c, 15d and optical repeaters 12a,
2b, 12c, constant current source 1 provided in peripheral device 13a
4. Each of the optical repeaters 12a, 12b, 1 from the constant current source 14
2c is provided with a power cable 16 for supplying power.

Here, the terminal equipment 13a and the terminal equipment 13b
Between the transmission optical fibers 15a to 15d
2a to 12c are connected to form an optical fiber transmission system. At this time, power is supplied to each of the optical repeaters 12a to 12c by the constant current source 14 provided in the peripheral device 13a.
To the power supply cable 16 to operate the relay circuits of the optical repeaters 12a to 12c by driving the constant current source. The constant current source 14 is connected to the peripheral device 13b.
May be provided.

FIG. 4 shows a conventional optical repeater. This optical repeater includes laser diodes 1a and 1b, photodiodes 2a and 2b, transistors 3a and 3b, a current control circuit 5, constant current sources 6a and 6b, and a Zener diode 7.

In this conventional optical repeater, a photodiode 2a is connected in pair with the laser diode 1a, and the anode of the laser diode 1a is connected to the collector of the transistor 3a, and the cathode of the laser diode 1a is connected to the emitter of the transistor 3a. Is done. The anode of the photodiode 2a and the base of the transistor 3a are connected to a current control circuit 5, and the cathode of the laser diode 1a is connected to a constant current source 6a.

Here, the photodiode 2a receives a part of the pumping light for the rare earth element-doped optical fiber amplifier emitted from the laser diode 1a, and controls the base voltage of the transistor 3a by the current control circuit 5. The intensity of the excitation light of the laser diode 1a is kept constant. At this time, the base voltage of the transistor 3a is controlled by the current control circuit 5 so that the sum of the currents flowing through the laser diode 1a and the transistor 3a becomes equal to the current value of the constant current source 6a. These circuits described above are referred to as upstream relay circuits.

Next, the downstream relay circuit is similarly constituted by the laser diode 1b, the photodiode 2b, the transistor 3b, and the constant current source 6b. The ascending and descending relay circuits and the current control circuit 5 are connected in parallel to the zener diode 7, whereby the laser diode 1 a
Up and down optical amplifiers are formed using each of the laser diode 1b and the laser diode 1b as an excitation laser, and a constant voltage circuit that operates by driving a constant current source is configured.

[0008]

However, according to the conventional optical repeater as shown in FIG. 4, two side diodes of the two laser diodes 1a and 1b are used as side current circuits.
Since the three transistors 3a and 3b are respectively connected in parallel, a large amount of current is supplied to the two up-link and down-link relay circuits.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an optical repeater capable of reducing a supply current in an optical repeater system operated by constant current driving.

[0010]

SUMMARY OF THE INVENTION The present invention has been described above eye
Laser diodes upstream and downstream to achieve
Up and down pump light emitted from the
Up and down rare earth element addition to amplify downstream optical signal
An optical repeater having an optical fiber amplifier,
And connected in series to the downstream laser diode
Up and down first to control the up and down pump light
A current control element and the upstream and downstream pump light are monitored.
Up and down to output up and down monitor signals
Photoelectric conversion element and the upstream and downstream laser diodes
And the upstream and downstream first current control elements.
Upstream and downstream connected in parallel to the upstream and downstream series circuits
A second current control element common to the downstream and the upstream and downstream pump light are controlled by controlling the currents of the upstream and downstream first current control elements based on the upstream and downstream monitor signals. Value, and a second current control element common to the upstream and downstream
And a current control circuit for controlling the sum of the currents of the current control elements to a predetermined value.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical repeater according to the present invention will be described in detail.

FIG. 1 shows an optical repeater of the present invention. This optical repeater includes laser diodes 1a and 1b, photodiodes 2a and 2b, transistors 3a and 3b, a transistor 4, a current control circuit 5, a constant current source 6, and a zener diode 7.

In the optical repeater of the present invention, the cathode of the laser diode 1a and the collector of the transistor 3a are connected. The photodiode 2a is connected in pair with the laser diode 1a, and the anode of the photodiode 2a and the base of the transistor 3a are connected to the current control circuit 5. The photodiode 2a is
A part of the excitation light of the laser diode 1a is received, and the base voltage of the transistor 3a is controlled by the current control circuit 5 so that the level of the excitation light becomes constant. The laser diode 1b, the photodiode 2b, and the transistor 3b have the same circuit configuration.

A circuit composed of the laser diode 1a, the photodiode 2a, and the transistor 3a and a circuit composed of the laser diode 1b, the photodiode 2b, and the transistor 3b are connected in parallel to the transistor 4, and are further fixed. The current source 6 is connected in series. Here, the base of the transistor 4 is a current control circuit 5
Connected to These laser diodes 1a, 1b,
Photodiodes 2a, 2b, transistors 3a, 3
b, and a circuit composed of the transistor 4 and a current control circuit 5 are connected in parallel to the Zener diode 7 to form up and down optical amplifiers using each of the laser diodes 1a and 1b as an excitation laser.

FIG. 2 shows an optical amplifier in the optical repeater of the present invention. Since the upstream and downstream optical amplifiers have the same configuration, only the upstream optical amplifier will be described below. This optical amplifier includes an optical isolator 8, a rare earth element-doped optical fiber 9, an optical multiplexer 10, and an optical isolator 11.

In the optical amplifier shown in FIG.
An optical isolator 8 that transmits light only in one direction on the N side
An optical multiplexer 10 is connected to the output side of the optical isolator 8 via a rare-earth-doped optical fiber 9. One side of the optical multiplexer 10 is connected to the optical isolator 11 and is located on the output terminal OUT side of the optical amplifier. Further, the optical multiplexer 10 is connected to the laser diode 1a by an optical fiber 12. Excitation light emitted from the laser diode 1a is input to the rare-earth-doped optical fiber 9, and amplifies an optical signal transmitted inside.

The operation of the optical repeater of the present invention having the above configuration will be described with reference to FIGS. In the optical repeater shown in FIG. 1, a part of the excitation light emitted from the laser diode 1a is received by the photodiode 2a, and the current control circuit 5 controls the transistor 3a so that the excitation light level becomes constant. Control the source voltage. Here, a circuit including the laser diode 1a, the photo diode 2a, and the transistor 3a is defined as an upstream relay circuit.

The relay circuit composed of the laser diode 1b, the photodiode 2b, and the transistor 3b operates in the same manner, and is referred to as a downstream relay circuit.
Further, the transistor 4 connected in parallel with the two upstream and downstream circuits is a bypass circuit of the upstream and downstream relay circuits, and the current flowing through the upstream relay circuit, the downstream relay circuit, and the transistor 4 The base voltage is controlled by the current control circuit 5 so that the sum becomes equal to the current value of the constant current source 6. These laser diodes 1a, 1b, photodiodes 2a, 2b, transistors 3a, 3b,
Since the circuit composed of the transistor 4 and the current control circuit 5 are connected in parallel to the Zener diode 7, the voltage between both ends is always constant. At this time, FIG.
In the optical amplifier, the pumping light emitted from the laser diode 1a is manually input to the rare-earth element-doped optical fiber 9 via the optical fiber 12 and the optical multiplexer 10, and amplifies the optical signal transmitted inside. Here, laser diode 1
The same applies to the excitation light emitted from b.

Next, another embodiment of the optical repeater of the present invention will be described. In the optical repeater shown in FIG. 1, the laser diode 1a, the photodiode 2a, and the transistor 3
Assuming that the connection of “a” is one unit, n units (n is a natural number of 3 or more) are connected in parallel with the transistor 4 to form n optical amplifiers for n transmission lines. Also in this case, the same effect can be obtained.

[0020]

As described above, according to the optical repeater of the present invention, the transistor 8 forming a bypass circuit is connected in parallel to a plurality of repeaters arranged in parallel for a plurality of transmission lines. Since only one is connected, the power supply current in the optical repeater system that operates by constant current driving can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of an optical repeater of the present invention.

FIG. 2 is a schematic diagram showing an optical amplifier of the optical repeater of the present invention.

FIG. 3 is a schematic diagram showing an optical fiber transmission system using a conventional optical repeater.

FIG. 4 is a schematic diagram showing a conventional optical repeater.

[Explanation of symbols]

 1a, 1b Laser diode 2a, 2b Photodiode 3a, 3b, 4 Transistor 5 Current control circuit 6, 6a, 6b Constant current source 7 Zener diode 8 Optical isolator 9 Rare earth doped fiber 10 Optical multiplexer 11 Optical isolator 12a, 12b, 12c Optical repeater 13a, 13b Terminal equipment 14 Constant current source 15a, 15b, 15c Transmission optical fiber 16 Power cable

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 10/00-10/28 H01S 3/094 H01S 3/10

Claims (4)

(57) [Claims] 1. The method according to claim 1, wherein the laser diodes are provided from upstream and downstream laser diodes.
The upward and downward pumping light is incident and the upward and downward
Upstream and downstream rare earth element doped optical amplifiers
In an optical repeater having a fiber amplifier, the upstream and downstream laser diodes are connected in series.
The upstream and downstream pump lights controlling the upstream and downstream pump light.
A first current control element, and monitoring the upstream and downstream pump light to monitor the upstream and downstream pump lights;
Up-going and down-going photoelectric conversion elements that output monitor signals, the up-going and down-going laser diodes, and the up-going and down-going
The first and second current control elements
The second common to the upstream and downstream connected in parallel to the series circuit
Current control element, the upstream and downstream based on the upstream and downstream monitor signals
By controlling the current of the downstream first current control element
The upstream and downstream pump light is controlled to a predetermined value, and
The up and down first current control elements and the up and down
The sum of the current of the second current control element common to the down
Characterized by having a current control circuit for controlling
Connection device. 2. The laser diode, the first current control element, and the photoelectric conversion element each include a pair of laser diodes for upstream and downstream transmission lines.
The optical repeater according to claim 1, further comprising a pair of MOS transistors and a pair of photodiodes, wherein the second current control element is formed by one MOS transistor common to the upstream and downstream transmission lines. 3. The optical repeater according to claim 1, wherein said series circuit and said second current control element are applied with a constant voltage by a constant voltage element connected in parallel. 4. The laser diode, the first current control element, and the photoelectric conversion element, respectively, for two or more transmission lines, two or more laser diodes, two or more MOS transistors, and two or more MOS transistors. The optical repeater according to claim 1, further comprising a photodiode, wherein the second current control element is formed by one MOS transistor common to the two or more transmission lines.