JPH10125988A - Optical fiber collective amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To amplify signal lights being propagated through cores collectively economically by injecting an excitation light into a part containing a light amplifying material of the clad of a multicore optical fiber. SOLUTION: Multicore optical fibers 10 and 20 have clads 12 and 22 not containing any light amplifying materials, and a plurality of cores 11 and 21. These cores 11 and 21 of the multicore optical fibers 10 and 20 are connected to a plurality of waveguide units 6 of a multiplexer 5 and the core 4 of a light amplifying optical fiber 1 for example with low losses. And when an excitation light 7 is injected into a clad part 2 containing a light amplifying material by using the multiplexer 5, the excitation light 7 of the multiplexer 5 excites the clad 2 part containing a light amplifying material of the light amplifying optical fiber 1, and causes it to have an amplification function. In this case, it is also possible to cause the multiplexer 5 to have a plurality of entrances for excitation lights 7. By doing this way, it is possible to obtain a light amplifier having a high amplification degree.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication technology used in the field of optical public communication, the field of optical LAN, and the like. More specifically, the present invention relates to a signal light propagating through a plurality of cores of an optical fiber. To a collective amplifier for amplifying all at once.

A conventional optical fiber amplifier is constituted by adding an optical amplification material such as erbium (Er) to a core, which is an optical waveguide portion of an optical fiber, and amplifying the signal light by using a multiplexer in the core. It operates by injecting excitation light to wake it up. On the other hand, a so-called multi-core optical fiber having a plurality of cores formed in a cladding has been proposed. If a conventional optical amplifier is used to optically amplify an optical signal propagating through such a multi-core optical fiber, a number of light sources corresponding to the number of cores is required, which is not economical.

Further, in order to optically amplify an optical signal propagating through a multi-core optical fiber, one high-power light source can be branched by a star coupler or the like and equivalently used as a plurality of light sources. In this case, a branch loss is added, and a high-output light source cannot be used effectively (amplification degree decreases). Further, there is a problem that the configuration of the multiplexer for multiplexing the signal light and the pump light becomes complicated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a collective optical fiber amplifier which can economically collectively amplify signal light propagating through a core in a multi-core optical fiber.

[0005]

In order to achieve the above object, the optical fiber collective amplifier according to the present invention has a plurality of cores disposed in a cladding and an optical amplification material added to at least a portion in contact with the core of the cladding. A multi-core optical fiber, and pump light is injected into a portion of the clad of the multi-core optical fiber to which the optical amplification material is added.

In the present invention, a multi-core optical fiber in which an optical amplifying material is added to the entire cladding may be provided. Further, a multi-core optical fiber in which an optical amplification material is added to a core may be provided. Further, a multiplexer for injecting the excitation light may be provided.

According to the present invention, the electromagnetic field in each core of the multi-core optical fiber simultaneously exudes to the cladding, and therefore, the excitation in the cladding to which the optical amplification material is added causes the propagation in the core. This was done by finding the fact that light could be amplified.

According to such an optical amplifier of the present invention, the signal light propagating in the core can be amplified simply by injecting the pumping light into the cladding in which the common optical amplifying material is added to each core. The amplifier can be configured with a multiplexer having a simple configuration, or the amplifier can be configured without a multiplexer, and a high-power light source for pumping can be effectively used without branch loss. As a result, an optical amplifier having a high amplification degree can be obtained with a simple configuration.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a cross section of a multi-core optical fiber 1 having a cladding to which an optical amplification material used for an optical amplifier according to the present invention is added. FIG. 1A shows a multi-core optical fiber 1 in which cores 4 are arranged in a line. FIG. B shows an example in which the cores 4 are two-dimensionally distributed in a clad having a circular cross section. In FIG. 2, reference numeral 2 denotes a portion of the cladding to which the optical amplification material is added, and reference numeral 3 denotes an outer portion of the cladding.

FIG. 2 shows such an optical amplification optical fiber 1.
FIG. 4 is a cross-sectional view showing an example of a collective amplifier configured using the above.
In the figure, 5 is a multiplexer, 6 is a signal light waveguide, 7 is pump light, and 8 is an arrow indicating a direction in which signal light propagates. Also, 10 and 20 are claddings without the addition of optical amplification material.
This is a multi-core optical fiber having 12 and 22 and a plurality of cores 11 and 21. These multi-core optical fibers 10 and 20
The plurality of cores 11 and 21 are connected to the plurality of signal optical waveguides 6 of the multiplexer 5 and the core 4 of the optical amplification optical fiber 1 with low loss. (In this figure, only two cores are shown for simplicity, but a typical multi-core optical fiber has more than two cores as described above.)

The optical amplifier of the present invention operates as follows. That is, when the pumping light 7 is injected into the clad portion 2 to which the optical amplification material is added by using the multiplexer 5, the excitation light 7 of the multiplexer 5 is added with the optical amplification material of the optical amplification optical fiber 1. The portion of the clad 2 that has been excited is excited to cause an amplification action.

In this case, as shown in FIG. 3, a plurality of entrances of the pumping light 7 can be provided in the multiplexer 5. In this way, it is possible to obtain an optical amplifier having a higher amplification degree than the optical amplifier shown in FIG.

FIG. 4 shows an example of an optical amplifier 1 which does not use a multiplexer. In this case, as shown in the figure, if the outer diameter of the optical fiber for optical amplification 1 is made larger than the outer diameter of the optical fibers 10 and 20 on both sides, the optical fiber is directly or optically applied to the common clad 2 to which the optical amplification material is added. The excitation light 7 can be injected using a fiber or the like. In such a configuration, a plurality of entrances of the excitation light 7 can be provided as shown in FIG. In this way, as described with reference to FIG. 2, an optical amplifier having a high amplification degree can be obtained.

In the above embodiment, a multi-core optical fiber in which a plurality of cores are arranged in a clad and a light amplifying material is added to a portion of the clad in contact with the core is used. Although the optical fiber collective amplifier configured to inject the pump light into the optical fiber is described above, in this case, a multi-core optical fiber in which the optical amplifying material is added to the entire cladding may be used, or the optical amplifying material is added to the core. Alternatively, a multi-core optical fiber may be used.

[0015]

As described above, according to the present invention, only by injecting the pumping light into the cladding to which the optical amplification material is added,
It is possible to amplify signal light propagating in a plurality of cores disposed therein, and to effectively use a high-power light source for pumping without causing branch loss, thereby realizing an optical amplifier having a high amplification degree. Therefore, a collective optical amplifier for a multi-core optical fiber can be economically obtained with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a multi-core optical fiber having a cladding to which an optical amplification material used for an optical amplifier of the present invention is added.

FIG. 2 is a cross-sectional view showing an example of a collective amplifier configured using the optical amplification optical fiber of FIG.

FIG. 3 is a cross-sectional view showing another example of a collective amplifier configured using the optical fiber for optical amplification of FIG. 1;

FIG. 4 is a cross-sectional view showing still another example of the collective amplifier constituted by using the optical fiber for optical amplification of FIG.

FIG. 5 is a sectional view showing still another example of the collective amplifier constituted by using the optical amplification optical fiber of FIG. 1;

[Explanation of symbols]

 1, 10, 20 Multi-core optical fiber 2 Part of cladding to which optical amplification material is added 3 Outer part of cladding 4, 11, 21 Core 5 Combiner 6 Signal optical waveguide 7 Excitation light 8 The direction in which signal light propagates Arrows 12, 22 shown Cladding with no light amplification material added

Claims (4)

[Claims] 1. A multi-core optical fiber having a plurality of cores disposed in a cladding and an optical amplification material added to at least a portion in contact with the core of the cladding, wherein the optical amplification material of the cladding of the multi-core optical fiber is added. An optical fiber batch amplifier, characterized in that pumping light is injected into a portion. 2. The optical fiber batch amplifier according to claim 1, further comprising a multi-core optical fiber in which an optical amplification material is added to the entire cladding. 3. A multi-core optical fiber having a core to which an optical amplification material is added.
2. The optical fiber batch amplifier according to 1. 4. The optical fiber batch amplifier according to claim 1, further comprising a multiplexer for injecting the pump light.