JP2917509B2 - Optical fiber amplifier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical fiber amplifier that amplifies a transmitted optical signal as it is.

[Prior Art] FIG. 3 is a diagram showing a configuration example of a conventional optical fiber amplifier.

In the figure, the optical fiber amplifier is composed of an erbium-doped optical fiber 31, a pumping light semiconductor laser 32 that generates pumping light, and a directional coupler 33 that causes the pumping light to enter the erbium-doped optical fiber 31, and converts an optical signal. It is inserted between optical fibers 34 and 35 for transmission.

The erbium-doped optical fiber 31 is excited by the energy of the excitation light having a wavelength of 1.49 μm or 0.98 μm,
It is possible to amplify an optical signal in the 1.55 μm band that passes. Therefore, for example, when used in an optical repeater,
Conventional processing for once converting an optical signal into an electric signal for amplification is not required, and reliability can be improved by simplifying a circuit configuration.

[Problems to be solved by the invention]

By the way, the conventional optical repeater performs not only amplification of an optical signal but also reproduction of a deteriorated signal waveform. Also, in the electric signal processing process, the state of the optical repeater is added to the surplus bits as a sub signal,
In the terminal equipment, the state of the optical repeater can be easily monitored.

However, although a conventional optical fiber amplifier can amplify the passing optical signal, it is necessary to superimpose the state of the optical repeater equipped with the optical fiber amplifier as a sub signal as a conventional signal and transmit it to the terminal equipment. Could not.

The present invention provides an optical fiber amplifier capable of increasing the number of optical signals passing therethrough and superimposing information indicating the state of a device such as an optical repeater on which the optical signals are mounted as an auxiliary signal on the optical signal. Aim.

[Means for solving the problem]

The invention according to claim 1 is an optical fiber amplifier which takes in pump light having a predetermined wavelength into an erbium-doped optical fiber and amplifies an optical signal having a predetermined wavelength passing through the erbium-doped optical fiber. And a bending loss applying means for giving a minute repetitive bending to the optical signal at a predetermined frequency and for intensity-modulating the optical signal by a change in the bending loss.

According to a second aspect of the present invention, there is provided an optical fiber amplifier for amplifying a main signal using an erbium-doped optical fiber, wherein the erbium-doped optical fiber is repeatedly bent at a predetermined frequency with a small frequency, and the main signal is changed by a bending loss change. And a sub-signal multiplexing control unit that drives the bending loss applying unit with a sub-signal having predetermined information, and intensity-modulates the main signal and superimposes the sub-signal. It is characterized.

According to a third aspect of the present invention, in the optical fiber amplifier according to any one of the first and second aspects, the bending loss applying means includes an optical fiber holding jig for holding the erbium-doped optical fiber on a wavy surface. And an actuator that drives the optical fiber holding jig and changes the bending pressure in accordance with the amplitude of the input control signal.

(Operation)

The invention described in claim 1 utilizes the fact that when a bend is given to an erbium-doped optical fiber, the intensity of the optical signal that is increased by the bending loss changes, and the optical signal is changed by changing the bending pressure. The intensity can be modulated.

According to the second aspect of the present invention, an optical signal amplified by an erbium-doped optical fiber is used as a main signal, a sub-signal having predetermined information is generated by a sub-signal multiplexing control unit, and a bending loss imparting unit is generated by the sub-signal. By driving, intensity modulation can be applied to the main signal according to the sub signal. That is, the bending loss applying means can superimpose the sub-signal on the main signal and transmit it together with the main signal.

According to the third aspect of the present invention, the optical signal (main signal) can be intensity-modulated by driving the optical fiber holding jig holding the erbium-doped optical fiber with the actuator and changing the bending pressure.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

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

In the figure, an optical fiber 34 for transmitting an optical signal is connected to an input port a of a directional coupler 33, and a pumping light semiconductor laser 32 for generating pumping light is connected to the input port b. An erbium-doped optical fiber 31 is connected to the output port c of the directional coupler, and further an optical fiber 35 for transmitting an optical signal is fusion-spliced. The optical signal enters the erbium-doped optical fiber 31 together with the excitation light via the directional coupler 33, is amplified, and is output to the optical fiber 35.

Here, the feature of the present invention is that, in the present embodiment, a bending loss applying section 11 for modulating the intensity of an optical signal is provided at a predetermined position of the erbium-doped optical fiber 31, and the bending loss applying section 11 is controlled by a sub-signal. Drive control is performed to superimpose a sub signal on an optical signal that is a main signal.

Here, the encoding circuit 12, the control circuit 13, and the modulation circuit 14 connected to the pumping light semiconductor laser 32 are an example of a sub-signal multiplexing control unit that generates a sub-signal that controls the bending loss applying unit 11. . That is, the encoding circuit 12 encodes output information of the APC circuit (output stabilization circuit) of the semiconductor laser 32 for excitation light and notifies the control circuit 13 of the output information. And outputs a corresponding signal. The modulation circuit 14 is configured to generate a sub-signal for driving the bending loss applying unit 11 based on a signal output from the control circuit 13.

FIG. 2 is a diagram showing a configuration example of the bending loss applying unit 11. As shown in FIG.

In the figure, the bending loss applying section 11 is composed of an optical fiber sandwiching jig 21 and an actuator 22 for driving the same. The surface on which the optical fiber sandwiching jig 21 sandwiches the erbium-doped optical fiber 31 is finely corrugated so as to efficiently apply a microbend loss to a 1.55 μm optical signal.

The sub-signal supplied from the modulation circuit 14 to the actuator 22 changes the pressure holding the erbium-doped optical fiber 31 according to the amplitude. The erbium-doped optical fiber 31 changes its microbend loss according to the change in its pressure, and can impart intensity modulation to the passing optical signal. That is, by applying intensity modulation to the optical signal amplified by the erbium-doped optical fiber 31 using the sub-signal, the information of the sub-signal can be transmitted. Incidentally, the modulation degree of the sub signal with respect to the main signal (optical signal) is suitably 15% or less.

In this way, by applying intensity modulation to the optical signal to be amplified and superimposing the state of the optical fiber amplifier on the optical signal,
It can transmit to the terminal equipment. Therefore, the state of the optical fiber amplifier can be detected by demodulating the intensity modulation component from the optical signal transmitted in the terminal station device.

For example, when the bending loss imparting section 11 is provided in the optical fiber 34 connected to the input port a of the directional coupler 33, the optical signal suffers a loss before being amplified by the erbium-doped optical fiber 31. The transmission of the main signal may be affected by noise. Therefore, the predetermined position of the erbium-doped optical fiber 31 that does not affect the transmission characteristics of the main signal is appropriate for the position where the bending loss applying unit 11 is provided.

〔The invention's effect〕

As described above, the optical fiber amplifier of the present invention
A sub signal having predetermined information can be superimposed on the optical signal to be amplified. Therefore, if the state of the optical fiber amplifier is generated as a sub signal, the sub signal can be transmitted together with the main signal, and the state of the optical fiber amplifier can be monitored at a remote place.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention, and FIG.
FIG. 3 is a diagram illustrating a configuration of a bending loss applying unit, and FIG. 3 is a diagram illustrating a configuration example of a conventional optical fiber amplifier. 11 Bending loss applying section, 12 Coding circuit, 13 Control circuit, 14 Modulation circuit, 21 Optical fiber pinching jig, 22
… Actuator, 31… erbium-doped optical fiber, 32… semiconductor laser for excitation light, 33… directional coupler, 34, 35… optical fiber.

Claims (3)

(57) [Claims] 1. An optical fiber amplifier for taking an excitation light having a predetermined wavelength into an erbium-doped optical fiber and amplifying an optical signal having a predetermined wavelength passing through the erbium-doped optical fiber, comprising: An optical fiber amplifier, comprising: a bending loss applying means for applying a minute repetitive bending in the above and intensity-modulating the optical signal by a change in the bending loss. 2. An optical fiber amplifier for amplifying a main signal using an erbium-doped optical fiber, wherein the erbium-doped optical fiber is repeatedly bent at a predetermined frequency, and the main signal is intensity-modulated by a bending loss change. A bending loss providing means, and a sub-signal multiplexing control means for driving the bending loss providing means with a sub signal having predetermined information, modulating the intensity of the main signal and superimposing the sub signal. Optical fiber amplifier. 3. The optical fiber amplifier according to claim 1, wherein the bending loss applying means comprises: an optical fiber holding jig for holding the erbium-doped optical fiber on a wavy surface; An optical fiber amplifier comprising: an actuator that drives a clamping jig and changes a bending pressure according to the amplitude of an input control signal.