JP2003273426A - Optical amplification apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost optical amplification apparatus that enables efficient amplification by being excited at 1.5x μm. <P>SOLUTION: An optical fiber 9 for excitation made of erbium (Er)-doped optical fiber is connected between the output end of a first excitation light source 3 for forward excitation and a first optical multiplexer 4. A 1.5 μm band ASE (natural emission light) is generated by excitation light from the first excitation light source 3. The ASE is introduced to the optical fiber 3 for amplification via the first optical multiplexer 4 to amplify signal light. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical amplification device for amplifying an optical signal used for communication or the like.

[0002]

2. Description of the Related Art As an optical amplifier for amplifying an optical signal, an EDFA (erbium-doped fiber) using an optical fiber doped with Erbium.
a conventional C-band (153)
0 nm to 1560 nm) as well as L band (156
EDFAs of 0 nm to 1600 nm) have also been put to practical use.

In the L-band EDFA, a wavelength of 1.48 μm or 0.
A light source of 98 μm is used, but the wavelength is 1.5 × μm
It is known that the power conversion efficiency doubles or more by performing excitation with excitation light of (1.52 μm to 1.58 μm).

[0004]

[Problems to be Solved by the Invention] However, 1.5
Semiconductor lasers capable of obtaining high output in the vicinity of x μm are not generally sold, and therefore, a semiconductor laser of 1.5 ×
The optical amplification device using the excitation light of μm has a drawback that it becomes very expensive.

The present invention has been made by paying attention to such a situation, and an object thereof is to perform 1.5 × μm pumping at low cost and to enable highly efficient amplification.

[0006]

In order to achieve the above object, the present invention is configured as follows.

That is, the optical amplifying device of the present invention is an optical amplifying device comprising a pumping light source for outputting pumping light, and an amplification optical fiber for amplifying and outputting signal light by the pumping light. ASE of 1.5 μm band
An excitation optical fiber that generates (spontaneous emission light) is provided, and the ASE is introduced into the amplification optical fiber.

Here, the 1.5 μm band means, for example, 1.
52 μm to 1.58 μm, preferably 1.52
It is μm to 1.56 μm.

According to the present invention, an excitation optical fiber for generating ASE (spontaneous emission light) in the 1.5 μm band by the excitation light from the excitation light source is provided, and the ASE in the 1.5 μm band is provided.
Can be introduced into the amplification optical fiber to amplify the signal light, and thereby the power conversion efficiency can be improved.

In one embodiment of the present invention, the pumping light is input from one end side of the pumping optical fiber, while the ASE is output from the other end side and introduced into the amplifying optical fiber. Is.

According to the present invention, the pumping optical fiber is interposed between the pumping light source and the optical multiplexer for multiplexing the signal light and the pumping light and supplying the pumping light to the amplification optical fiber. realizable.

In a preferred aspect of the present invention, the pumping light is input from one end side of the pumping optical fiber, while the ASE is output from the one end side and introduced into the amplifying optical fiber. Is.

According to the present invention, the ASE is output from one end side of the pumping optical fiber into which the pumping light is input, that is, the pumping light input end and the ASE output end are made the same. As compared with the configuration in which the excitation light is input from one end side and the ASE is output from the other end side of the
E can be generated and the pumping power introduced into the amplification optical fiber can be increased.

In another embodiment of the present invention, a reflecting means for reflecting the ASE to the one end side is provided on the other end side of the pumping optical fiber.

According to the present invention, since the ASE is reflected toward the one end by the reflecting means such as the mirror provided on the other end of the pumping optical fiber, the ASE output from the one end.
Becomes larger, the pumping power introduced into the amplification optical fiber can be further increased.

Further, the optical amplifying device of the present invention is provided with a pumping light source that outputs pumping light, an optical multiplexer that multiplexes the pumping light and the signal light, and an output of the optical multiplexer, In an optical amplifier including an amplification optical fiber that amplifies and outputs light, a pumping optical fiber into which the pumping light from the pumping light source is introduced, and A generated in the pumping optical fiber
An oscillating light supply unit including a resonator that oscillates a 1.5 μm band of SE (spontaneous emission light) is provided, and the optical combiner uses the 1.5 μm band oscillating light from the oscillating light supply unit as excitation light And is combined with the signal light and introduced into the amplification optical fiber.

According to the present invention, the lasing light supply means oscillates the 1.5 μm band of ASE generated in the pumping optical fiber, and introduces the oscillating light in the 1.5 μm band into the amplifying optical fiber as pumping light. Then, the signal light is amplified, so that the power conversion efficiency can be improved. Also, A
Since the SE 1.5 μm band is oscillated, a larger power can be taken out.

In one embodiment of the present invention, the resonator includes a pair of optical fiber gratings arranged at both ends of the pumping optical fiber, and the pumping light source is provided from one end of the pumping optical fiber. While the excitation light is input, the oscillated light is output from the other end of the optical fiber for excitation and input to the optical multiplexer.

According to the present invention, the pumping optical fiber and the pair of optical fiber gratings are interposed between the pumping light source and the optical multiplexer for multiplexing the signal light and the pumping light and supplying the pumping light to the amplification optical fiber. It can be realized with a relatively simple configuration.

In a preferred aspect of the present invention, the resonator includes an optical fiber grating arranged on one end side of the pumping optical fiber and a reflection mirror arranged on the other end side of the pumping optical fiber. The excitation light of the excitation light source is input from the one end side of the fiber, while the oscillation light is output from the one end side and input to the optical multiplexer.

When a pair of optical fiber gratings are arranged at both ends of the pumping optical fiber to form a resonator, it is necessary to match the reflection wavelengths of the pair of optical fiber gratings. This is not necessary, and the accuracy for the optical fiber grating is relaxed.

In another embodiment of the present invention, the amplification optical fiber and the pumping optical fiber are formed of one optical fiber, and the signal light is transmitted to the one optical fiber. The optical fibers are spliced and spliced.

According to the present invention, the amplification optical fiber and the excitation optical fiber are composed of one optical fiber, and the optical fiber for transmitting the signal light is melt-spliced and connected to the one optical fiber. Therefore, as compared with the case where the amplification optical fiber and the pumping optical fiber are individually configured and connected, the number of connection points is reduced, and the loss due to the connection can be reduced.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing an overall configuration of an optical amplifying device 1 according to one embodiment of the present invention.

The optical amplifying device 1 of this embodiment has a first pumping light source 3 for forward pumping and a first pumping light source 3 for pumping pumping light into the amplification optical fiber 2 from the same direction as the signal light.
Is a bidirectional pumping type including a second pumping light source 5 for backward pumping and a second optical multiplexer 6 for providing pumping light in the opposite direction to the signal light. , The signal light input side and output side are respectively
Second optical isolators 7 and 8 are provided.

The amplification optical fiber 2 is, for example, an erbium (Er) -doped optical fiber, and the first and second pumping light sources 3 and 5 are, for example, 1.48 μm or 0.98 μm.
m is a laser diode for excitation.

In this embodiment, in order to enhance the power conversion efficiency without using a 1.5 × μm pumping light source, the following is performed.

That is, in this embodiment, an excitation optical fiber made of an erbium (Er) -doped optical fiber is provided between the output end of the first excitation light source 3 for forward excitation and the first optical multiplexer 4. 9 is connected to the ASE (Amplified S) by the excitation light from the first excitation light source 3.
Puntaneous Emission (spontaneous emission light) is generated, and this ASE is introduced into the amplification optical fiber 2 via the first optical multiplexer 4 to amplify the signal light.

The center wavelength of the ASE generated in the pumping optical fiber 9 by the pumping light of 1.48 μm or 0.98 μm is around 1.53 μm, and the ASE in the wavelength band of 1.5 μm is amplified by the optical fiber for amplification. The power conversion efficiency can be improved by introducing into No. 2 and exciting.

If the pumping optical fiber 9 becomes longer, the rate of conversion of the pumping light into ASE in the 1.5 μm band increases, but the efficiency decreases when the pumping light is converted into ASE. The power conversion efficiency can be improved as a whole by optimizing the length of the optical fiber 9.

According to this embodiment, even if the pumping light from the pumping light source 3 is not completely absorbed by the pumping optical fiber 9, the remaining pumping light is transmitted to the amplifying optical fiber 2 as A
Since it is introduced together with SE, the efficiency of signal amplification in the amplification optical fiber 2 can be increased as a result.

As described above, the AS of the 1.5 μm band can be obtained with a relatively simple structure without using the 1.5 × μm excitation light source.
The power conversion efficiency can be improved by E. Therefore, the amplification optical fiber 2 shorter than the conventional one can achieve the same power conversion efficiency as the conventional one, and can reduce the NF (noise figure).

Although the amplification optical fiber 2 and the pumping optical fiber 9 are separate erbium-doped optical fibers in this embodiment, they are shown in FIG. 2 as another embodiment of the present invention. So that the amplification optical fiber 2
The pumping optical fiber 9 and the pumping optical fiber 9 may be composed of one erbium-doped optical fiber, and the transmission optical fiber 10 for transmitting signal light may be melt-stretched and connected to the one erbium-doped optical fiber. In this case, the EDM direct connection type WDM coupler 11 may be used as the first optical multiplexer 4. As a result, the number of connection points can be reduced, the loss due to connection can be reduced, and the power conversion efficiency can be improved.

Further, in the embodiment of FIG. 1, an optical isolator is provided between the optical multiplexer 4 and the pumping optical fiber 9.
If it is arranged between the optical multiplexer 4 and the amplification optical fiber 2,
The influence of oscillation or the like due to the return of ASE can be suppressed, and more stable amplification characteristics can be obtained. Further, the optical isolator 7 in FIG. 1 may be arranged between the optical multiplexer 4 and the amplification optical fiber 2, and in this case, there is an advantage that one optical isolator can block the returning light.

(Embodiment 2) FIG. 3 is a diagram showing an overall configuration of an optical amplifying device 1'of another embodiment of the present invention.
Parts corresponding to those in FIG. 1 are designated by the same reference numerals.

In the above-described embodiment, the ASE output from the one end 9a of the pumping optical fiber 9 and the other end 9b of the pumping optical fiber 9 is introduced into the amplifying optical fiber 2. In the fiber, it is possible to extract a larger ASE by extracting the ASE from the input end for inputting the pumping light than by extracting the ASE from the output end.

Therefore, in this embodiment, the pumping light from the first pumping light source 3 is input from one end 9a of the pumping optical fiber 9 via the third optical multiplexer 12, and the one end 9a is also supplied. The output ASE is introduced into the amplifying optical fiber 2 via the third and second optical multiplexers 12 and 4, whereby the power conversion efficiency can be further improved.

Other configurations and effects are similar to those of the above-described embodiment.

(Embodiment 3) FIG. 4 is a diagram showing an overall configuration of an optical amplifying device 1 ″ according to still another embodiment of the present invention, in which parts corresponding to those of the above-described Embodiment 2 are not shown. , With the same reference numerals.

In this embodiment, the optical fiber 9 for excitation is used.
The other end 9b of the mirror 13 is provided with a mirror 13 that reflects ASE and returns to the one end 9a side.
The ASE toward the other end 9b and the pumping light that could not be absorbed in the pumping optical fiber 9 are returned to the one end 9a side to increase the power of the ASE, and the remaining pumping light can be incident on the amplification optical fiber 2. Therefore, the power conversion efficiency can be further enhanced.

In the third and fourth embodiments, in order to obtain more stable amplification characteristics, an optical isolator is provided between the multiplexer 4 and the multiplexer 12, and the multiplexer 4 and the amplification optical fiber 2 are used. It may be placed between and. Further, an optical isolator may be arranged only between the multiplexer 4 and the amplification optical fiber 2.

(Embodiment 4) FIG. 5 is a diagram showing an overall configuration of an optical amplifying device 1 '''according to still another embodiment of the present invention, in which portions corresponding to those in FIG. , With the same reference numerals.

The optical amplifying device 1 '''of this embodiment is
Similar to the above-described embodiment, the first pumping light source 3 for forward pumping and the first optical multiplexer 4 for making pumping light incident on the amplification optical fiber 2 from the same direction as the signal light are provided. At the same time, it is a bidirectional pump type that includes a second pumping light source 5 for backward pumping and a second optical multiplexer 6 for pumping pumping light from the direction opposite to the signal light, and First and second optical isolators 7 and 8 are provided on the output side, respectively.

The amplification optical fiber 2 is, for example, an erbium (Er) -doped optical fiber, and the first and second pumping light sources 3 and 5 are, for example, 1.48 μm or 0.98 μm.
m is a laser diode for excitation.

Also in this embodiment, 1.5 × μm
In order to increase the power conversion efficiency without using the pumping light source of No. 3, the output end of the first pumping light source 3 for forward pumping and the first optical multiplexer 4 are used as in the embodiment of FIG. 1 described above. An excitation optical fiber 9 composed of an erbium (Er) -doped optical fiber is connected between the two.

Further, in this embodiment, a pair of light as a resonator for oscillating the 1.5 μm band of ASE (spontaneous emission light) generated in the pumping optical fiber 9 is provided on both sides of the pumping optical fiber 9. Fiber Bragg gratings (hereinafter referred to as “FBGs”) 15a and 15b are provided, and oscillation light in the 1.5 μm band is supplied to the first optical multiplexer 4 by the excitation optical fiber 9 and the FBGs 15a and 15b. It constitutes the supply means.

The FBGs 15a and 15b selectively reflect light of a specific wavelength, and in this embodiment,
The reflection center wavelength is, for example, 1.55 μm.
The reflectance of the FBG 15a on the first excitation light source 3 side is, for example, about 100%, and the reflectance of the FBG 15b on the first optical multiplexer 4 side is smaller than 100%.

In this embodiment, the first excitation light source 3
The excitation light from the laser light passes through the FBG 15a to excite the optical fiber 9 for excitation, and ASE (spontaneous emission light) is generated. ASE of 1.55 μm in this ASE is FBG15
a and 15b are selectively fired and oscillate.
The oscillated light of μm passes through the FBG 15b, is supplied to the first optical multiplexer 4, is combined with the signal light, is introduced into the amplification optical fiber 2, and is amplified.

In this way, by introducing the oscillation light of the 1.5 μm band into the amplification optical fiber 2 and exciting it, it is possible to improve the power conversion efficiency as in the above-mentioned embodiment.

Furthermore, A generated in the optical fiber 9 for excitation
By oscillating and supplying the 1.5 μm band of SE (spontaneous emission light), the energy in the excitation level can be efficiently extracted and a large power can be extracted.

The length of the pumping optical fiber is optimized to obtain the required power for the 1.5 μm band oscillated light, while the unabsorbed pumping light is directly passed to the first optical multiplexer 4. The power conversion efficiency can be improved as a whole by supplying.

Moreover, in this embodiment, the pumping light from the first pumping light source 3 is input and oscillated, and this oscillating light is multiplexed with the signal light by the first optical multiplexer 4. Therefore, compared to a configuration in which the pumping light from the pumping light source and the signal light are combined by a multiplexer and then input to the pumping optical fiber to oscillate, there is no problem that the output varies depending on the signal light. . That is, in the configuration that oscillates after the signal light and the pumping light are multiplexed, when the wavelength of the input signal light changes, stable oscillation cannot be performed because the loss in the pumping optical fiber changes. , While the oscillation power fluctuates and the output power also fluctuates,
In this embodiment in which only the pumping light is input to the pumping optical fiber, there is no such problem.

In this embodiment, the amplification optical fiber 2 and the pumping optical fiber 9 are composed of one erbium-doped optical fiber as in the above-described embodiments, and the one erbium-doped optical fiber is used. For optical fiber,
An optical fiber for transmission that transmits signal light may be spliced and spliced.

An optical isolator is used as the optical multiplexer 4 and F
If it is arranged between the BG 15b and between the optical multiplexer 4 and the amplification optical fiber 2, more stable amplification characteristics can be obtained. Further, the optical isolator 7 in FIG. 1 may be arranged between the optical multiplexer 4 and the amplification optical fiber 2.

(Embodiment 5) FIG. 6 is a diagram showing an overall configuration of an optical amplifying device 1 ″ ″ according to still another embodiment of the present invention, which corresponds to the above-described Embodiment 4. Are denoted by the same reference numerals.

In the above-described embodiment, the pumping light is input from one end 9a of the pumping optical fiber 9 and the oscillation light output from the other end 9b is introduced into the amplifying optical fiber 2. Then, the pumping light from the first pumping light source 3 is transmitted through the third optical multiplexer 12 to the pumping optical fiber 9
The oscillated light in the 1.5 μm band that is input from one end 9a of the above and is output from the one end 9a is introduced into the amplification optical fiber 2 via the third and second optical multiplexers 12 and 4. Further, in this embodiment, the pumping optical fiber 9
The FBG 15a is provided on one end 9a side, while the mirror 13 is provided on the other end 9b of the pumping optical fiber 9, and the mirror 13 and the FBG 15a form a resonator.

FIG. 5 using a pair of FBGs 15a and 15b.
In the above configuration, it is necessary to match the reflection wavelengths of the two FBGs 15a and 15b with each other, but in this embodiment, there is no need to do so, and the accuracy for the FBG 15a is relaxed.

The other structure is similar to that of the fourth embodiment.

Incidentally, instead of the third optical multiplexer 12, FIG.
The optical circulator 16 shown in FIG.

(Other Embodiments) In each of the above-described embodiments, the pumping optical fiber 9 is connected to the first pumping light source 3 side for forward pumping, but as another embodiment of the present invention, An optical fiber for pumping may be connected to the second pumping light source 5 side for backward pumping.

Although each of the above-described embodiments has been described by applying to the bidirectional pumping type optical amplifying device, the present invention can be applied to either the forward pumping type or the backward pumping type optical amplifying device. is there.

As another embodiment of the present invention, the amplification optical fiber 2 may be divided into two and an isolator or a gain equalizer may be inserted in the middle thereof to further improve the conversion efficiency.

[0064]

As described above, according to the present invention, an excitation optical fiber for generating ASE (spontaneous emission light) in the 1.5 μm band by the excitation light from the excitation light source is provided.
The m-band ASE is introduced into the amplification optical fiber to amplify the signal light, or the AS generated in the excitation optical fiber
The 1.5 μm band of E is oscillated, and the oscillated light in the 1.5 μm band is introduced into the optical fiber for amplification as the excitation light to amplify the signal light. Therefore, it is expensive to output the excitation light in the 1.5 μm band. The power conversion efficiency can be improved without using a semiconductor laser or the like.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a multiplexer when the amplification optical fiber and the excitation optical fiber are configured by one optical fiber.

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

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

FIG. 5 is a configuration diagram of an optical amplifier device according to another embodiment of the present invention.

FIG. 6 is a configuration diagram of an optical amplifying device according to still another embodiment of the present invention.

FIG. 7 is a configuration diagram of an optical amplifying device according to another embodiment of the present invention.

[Explanation of symbols]

2 Optical fiber for amplification 3,5 First and second excitation light sources 4, 6, 12 First to third optical multiplexers 9 Optical fiber for excitation 13 mirror 15a, 15 FBG

Claims (8)

[Claims] 1. An optical amplifying device comprising a pumping light source for outputting pumping light and an amplification optical fiber for amplifying and outputting signal light by the pumping light, wherein an ASE (natural) of 1.5 μm band is generated by the pumping light. An excitation optical fiber for generating emitted light),
Is introduced into the amplification optical fiber. 2. The optical amplifying device according to claim 1, wherein the pumping light is input from one end of the pumping optical fiber, and the ASE is output from the other end of the pumping optical fiber and introduced into the amplifying optical fiber. . 3. The pumping light is input from one end side of the pumping optical fiber, while the ASE is output from the one end side and introduced into the amplification optical fiber.
The optical amplification device described. 4. The optical amplifying device according to claim 3, wherein a reflecting means for reflecting the ASE to the one end side is provided on the other end side of the pumping optical fiber. 5. An excitation light source that outputs excitation light, an optical multiplexer that combines the excitation light and the signal light, and an amplifier that introduces the output of the optical multiplexer and that amplifies and outputs the signal light. In an optical amplifying device including a pumping optical fiber, a pumping optical fiber into which pumping light from the pumping light source is introduced, and a 1.5 μm band of ASE (spontaneous emission light) generated in the pumping optical fiber An oscillating light supply unit including a resonator is provided, and the 1.5 μm band oscillating light from the oscillating light supply unit is used as excitation light to combine the signal light with the optical combiner to amplify the optical fiber for amplification. An optical amplifying device characterized by being introduced into. 6. The resonator includes a pair of optical fiber gratings arranged at both ends of the pumping optical fiber, and pumping light of the pumping light source is input from one end of the pumping optical fiber. On the other hand, the optical amplifier according to claim 5, wherein the oscillated light is output from the other end of the pumping optical fiber and input to the optical multiplexer. 7. The resonator includes an optical fiber grating arranged on one end side of the pumping optical fiber and a reflection mirror arranged on the other end side, and the resonator is provided from the one end side of the pumping optical fiber. An optical amplification device in which the pumping light of a pumping light source is input, while the oscillated light is output from the one end side and input to the optical multiplexer. 8. The amplification optical fiber and the excitation optical fiber are formed by one optical fiber, and
The optical amplification device according to claim 2 or 6, wherein an optical fiber for transmitting the signal light is melt-spliced and connected to a book optical fiber.