JP2001036169A - Bilateral pumping light amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bilateral pumping light optical amplifier which makes an optical isolator unnecessary and applies a light emitting element with an FBG to a pumping light source. SOLUTION: Pumping lights, generated from pumping light sources 2, 3, are supplied to an EDF through Mach-Zehnder type wavelength multiplexing couplers 4. Two or more front and rear pumping light sources 2, 3 are installed. Pumping lights of different wavelengths are generated from all four or more pumping light sources 2, 3. For the wavelengths, the front and rear pumping lights are arranged alternately, and the longest wavelength of the front pumping lights is made shorter than the shortest wavelength of the rear pumping lights. The wave couplers 4 and an LD module with an FBG correspond to a pumping band in the vicinity of 1480 nm or 980 nm. The level of residual pumping lights, outputted from vacant ports of the wave couplers 4 can be monitored. Based on the monitored result, the levels of both the front pumping light source 2 and the rear pumping light source 3 or the level of one of them are adjusted, and the amplification level of the EDF is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical amplifier used in an optical communication system, and more particularly, to an amplified optical fiber (ED).
F) is a bidirectionally pumped optical amplifier that pumps F) from front and rear.

[0002]

2. Description of the Related Art An optical fiber amplifier (EDFA) using an EDF doped with erbium has been rapidly commercialized in recent years and has been adopted as an optical amplifier in an optical fiber communication system. Above all, application to a wavelength division multiplexing (WDM) system, in which signal light (channels) having a plurality of different wavelengths is multiplexed by a wavelength division multiplexer and transmitted as a wavelength division multiplexed signal, thereby increasing the transmission capacity, has been attracting attention. I have. ED
The FA can amplify the wavelength-multiplexed signal light at a time, and is expected to be a simple linear repeater replacing a conventional regenerative repeater in a WDM system.

However, when the EDFA is applied to the WDM system, the problem is the output characteristic of the EDFA. That is, as the number of channels increases to 1, 2,... N, the output of the EDFA becomes 1, 2,. The EDFA basically includes an EDF as an amplification medium, an excitation light source for exciting the EDF, and a multiplexer for introducing the excitation light from the excitation light source into the EDF. In this case, it is important to prepare a high-output excitation light source for achieving high output.

In order to increase the output of the EDFA by increasing the intensity of the excitation light, the excitation light has been supplied to the EDF by the following method. (1) As shown in FIG. 5, before and after the EDF, the excitation light sources A and B
And the excitation light from the forward excitation light source A is
Forward pumping to supply the signal light through the same direction to excite the EDF, and backward pumping to supply the pumping light from the rear pumping light source B through the rear multiplexer D from the opposite direction to the signal light to excite the EDF. A bidirectional excitation method that excites from both directions by combining the two methods. (2) As shown in FIG. 6, two pump light sources A ₁ and A ₂ for generating a single-polarized pump light in front of the EDF and two pump light sources for generating a single-polarized pump light behind the EDF. The light sources B ₁ and B ₂ are inserted, and the pump lights generated from the front pump light sources A ₁ and A ₂ are combined by the front polarization combining element E, and the combined light is passed through the front multiplexer C in the same direction as the signal light. From the rear pump light source B ₁ , B ₂ , and the pump light generated from the rear pump light sources B ₁ and B ₂ is combined by the backward polarization combining element E, and the combined light is passed through the backward multiplexer D from the opposite direction to the signal light. A method of supplying and exciting EDF. (3) It is assumed that the front pump light sources A ₁ and A ₂ and the rear pump light sources B ₁ and B ₂ shown in FIG. 6 generate pump lights having different wavelengths, and the pump light from the front pump light sources A ₁ and A ₂ is used. The light is synthesized by the front wavelength multiplexing element F, supplied through the front multiplexer C from the same direction as the signal light to excite the EDF, and the pump light from the rear pump light sources B ₁ and B _{2 is} converted to the rear wavelength. A method of combining with a multiplexing element F and supplying it from the opposite direction to the signal light through a rear multiplexer D to excite the EDF. (4) A method combining the above three methods.

In the bidirectional excitation method (1), the EDF
There is excitation light (residual excitation light) that is not used for the excitation, other than the excitation light that is injected into the EDF and excites the EDF. This residual pump light may enter the pump light source on the side opposite to the pump light source that has been emitted, making the output of the pump light source unstable or damaging. In order to prevent this, it is essential to insert an optical isolator G at the output end of the pump light source as shown in FIGS.

In the pumping method (2), since the polarization combining element E can multiplex only two pump lights, there is a limit in increasing the output of the pump light.

[0007] In excitation method (3), there is no limit to the number of multiple possible excitation light in theory if wavelength multiplexing element F is within the effective excitation wavelength range, in reality excitation light source A ₁ A
_2, B _1, since the output spectrum of B ₂ there is a range, efficient multiplicity by multiplexing the wavelength characteristics of the wavelength multiplexing element F is limited. For example, the most common 1480 nm semiconductor laser diode (LD) as an excitation light source for EDFAs
Oscillates in vertical multimode, and its spectrum width is 5 nm
It is about. On the other hand, the effective excitation wavelength band of the EDFA near 1480 nm is 50n from 1450 nm to 1500 nm.
m, so that three-wavelength multiplexing is actually the limit.

In recent years, as shown in FIG. 7, a semiconductor laser diode module (LD with FBG) having a narrowed spectrum width by providing a fiber Bragg grating (FBG) as an external resonator outside the semiconductor laser diode (LD). Module) is being put to practical use. This is provided with an FBG in a part of an optical fiber connected to a semiconductor laser, and its output spectrum width is narrowed to about 1 nm as compared with the conventional one without an FBG as shown in FIG. Thus, higher-density wavelength multiplexing is possible.

In recent years, as a wavelength division multiplexing device, a Maha-Zehnder type wavelength multi-wavelength device using a fused fiber or a quartz waveguide device has been developed. FIG. 9A is a schematic diagram thereof, and FIG.
(B) shows the transmission spectrum. FIG. 10 shows an example of a 1 × 8 Mahachender-type wavelength-multiplexed wave device. This wavelength-multiplexed wave device has 1 × 8 ports, and n (= 1, 2,...)
8) When light having different center wavelengths and equally spaced in frequency is input from the ports, the lights are multiplexed and output from the 0 port. FIG. 11 shows the transmission characteristics of each port of the 1 × 8 Mach-Zehnder type multi-wavelength optical device.

As described above, an LD module with an FBG capable of narrowing the spectrum width and enabling high-density wavelength multiplexing, and a Mach-Zehnder-type multi-wavelength multiplexer capable of efficiently multiplexing many lights having different center wavelengths. With the advent of this, an excitation light source having a higher output can be realized, and if this can be used as an excitation light source for an EDFA, the EDFA can be easily and effectively increased in output.

[0011]

However, when the LD module with FBG is used as an excitation light source of an EDFA, there are the following problems. (1) As described above, in FIGS. 5 and 6, there is a possibility that the excitation light generated from the excitation light source becomes unstable or the excitation light source is damaged due to the residual excitation light. To prevent this, an optical isolator is indispensable. However, since an LD module with an FBG has an FBG as an external resonator, an optical isolator cannot be built therein. (2) For the above reason, the optical isolator must be provided externally or inserted after multiplexing the pump light output from the LD module with FBG. By doing so, it is possible to avoid the possibility of instability of the pump light output and the damage of the pump light source due to the incidence of the residual pump light, but there is a new problem that the pump light intensity decreases due to the insertion loss of the optical isolator. is there.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide an EDFA.
It is an object of the present invention to solve the above-mentioned problems of the optical communication system using the optical communication. In order to realize the object, the present invention uses FBG as the excitation light source.
Using a LD module with a pump, and using a Mach-Zehnder multi-wavelength multiplexer as a multiplexer for transmitting the excitation light from the excitation light source to the EDFA, and further having different wavelengths for the forward excitation light and the backward excitation light. This eliminates the need for an optical isolator.

The first bidirectional pumping optical amplifier of the present application is:
In a bidirectional pumping optical amplifier (EDFA) in which an amplification optical fiber (EDF) is pumped from the front by pumping light from a forward pumping light source and pumped from behind by pumping light from a backward pumping light source, both pumping light sources are semiconductor laser diode modules. (LD module with FBG), pumping light generated from each pumping light source is supplied to an amplification optical fiber (EDF) through a Mach-Zehnder type wavelength-multiplexed wave filter, and pumping of different wavelengths is performed from a forward pumping light source and a backward pumping light source. Light is emitted.

The second bidirectional pumping optical amplifier of the present application is:
In a bidirectional pumping optical amplifier that pumps an amplification optical fiber (EDF) from the front with pumping light from a forward pumping light source and pumps it from behind with pumping light from a backward pumping light source, both pumping light sources are connected to a semiconductor laser diode module (with FBG). LD module), and the pump light generated from each pump light source is supplied to an amplification optical fiber (EDF) through a Mach-Zehnder multi-wavelength multi-wave device, and the forward pump light source (2) and the backward pump light source (3) are respectively supplied. Two or more excitation light sources (2, 3) emit excitation light of different wavelengths.

[0015] The third bidirectional pumping optical amplifier of the present application is:
In a bidirectional pumping optical amplifier that pumps an amplification optical fiber (EDF) from the front with pumping light from a forward pumping light source and pumps from the back with pumping light from a backward pumping light source, both pumping light sources are equipped with semiconductor laser diode modules (with FBGs). LD module), the pump light generated from each pump light source is supplied to an amplification optical fiber (EDF) through a Mach-Zehnder multi-wavelength multi-wave device, and two or more forward pump light sources and two or more backward pump light sources are provided. The wavelengths of the excitation lights emitted from the light sources are different from each other, and the excitation light and the rear excitation light are arranged alternately.

The fourth bidirectional pumping optical amplifier of the present application is:
In a bidirectional pumping optical amplifier that pumps an amplification optical fiber (EDF) from the front with pumping light from a forward pumping light source and pumps from the back with pumping light from a backward pumping light source, both pumping light sources are equipped with semiconductor laser diode modules (with FBGs). LD module), the pump light generated from each pump light source is supplied to an amplification optical fiber (EDF) through a Mach-Zehnder multi-wavelength multi-wave device, and two or more forward pump light sources and two or more backward pump light sources are provided. The wavelengths of the pumping lights emitted from the light sources are different from each other, and the longest wavelength of the forward pumping light is shorter than the shortest wavelength of the backward pumping light.

The fifth bidirectional pumping optical amplifier of the present application is:
The bidirectional pumping optical amplifier according to any one of claims 1 to 4, wherein the Mach-Zehnder type multi-wavelength optical multiplexer and the semiconductor laser diode module (LD module with FBG) correspond to an excitation band near 1480 nm. It is what it was.

The sixth bidirectional pumping optical amplifier of the present application is:
The bidirectional pumping optical amplifier according to any one of claims 1 to 4, wherein the Mach-Zehnder type multi-wavelength optical multiplexer and the semiconductor laser diode module (LD module with FBG) correspond to an excitation band around 980 nm. It is what it was.

The seventh bidirectional pumping optical amplifier of the present application is:
The bidirectional pumping optical amplifier according to any one of claims 1 to 6, wherein the level of the residual pumping light emitted from an empty port of the Mach-Zehnder multi-wavelength wavelength multiplexer can be monitored.

The eighth bidirectional pumping optical amplifier of the present application is:
The bidirectional pumping optical amplifier according to any one of claims 1 to 6, wherein a level of the residual pumping light emitted from an empty port of the Mach-Zehnder type multi-wavelength wavelength monitor is monitored,
The level of one or both of the forward pumping light source and the backward pumping light source is adjusted based on the monitoring result to control the EDF amplification level.

[0030]

(Embodiment 1) FIG. 1 shows a first embodiment of a bidirectional pumping optical amplifier according to the present invention. This is to excite an amplification optical fiber (EDF) from the front by the excitation light from the forward excitation light source 2 and from the rear by the excitation light from the rear excitation light source 3. A 1 × 2 port Mach-Zehnder multi-wavelength multiplexer 4 is connected via a coupler) 10 and one of the input ports P of the Mach-Zender multi-wavelength multi-wave detector 4 is connected.
1, a front pumping light source 2 is connected, and a rear 1 × 2 port Mach-Zehnder multi-wavelength multi-wave device 4 is connected to the rear of the EDF via a rear multiplexer (WDM coupler) 12, and the Mach-Zender type is connected. One input port P2 of the wavelength-multiplexed wave device 4
Is connected to the backward excitation light source 3. In addition, the semiconductor laser diode modules (F
(LD module with BG), and the excitation light of different wavelengths is emitted from the front excitation light source 2 and the rear excitation light source 3.

The Mach-Zehnder multi-wavelength wavelength-multiplexing device 4 used in the present invention has a basic structure shown in FIG. 9 (a), and has a transmission intensity I of ports 1 → 3 and ports 1 → 4.
₁₃ (λ) and I ₁₄ (λ) are expressed as in Equation 1. However,
α: branching rate, τ: delay amount due to a difference between two paths,
Φ: initial phase. _{I 13 (λ) = 1-4α (} 1-α) sin 2 (πcτ / λ + φ / 2) I 14 (λ) = 4α (1-α) sin 2 (πcτ / λ + φ / 2) ··· ( wherein 1 FIG. 9B shows a transmission intensity spectrum of the Mahachender-type wavelength-multiplexed wave device 4. As can be seen from Equation 1 and FIGS. 9 (a, b), at the wavelength where the transmittance is maximum at port 1 → 3, the transmittance of port 1 → 4 is −40 dB or less, and has very high isolation. . Similarly 1 ×
The characteristics of a Mahachender-type wavelength-multiplexed wave filter composed of n ports and designed to transmit a wavelength λn with a high transmittance at the port n have a wavelength λm (1 ≦ 1) incident from the port 0.
m ≦ n) is coupled only to port m and the other port 1
(1 ≦ m ≦ and 1 ≠ m), so port n
In this case, the wavelengths λ1 and λm can be sufficiently isolated.

FIG. 10 shows a 1 × 8-port Mach-Zehnder type wavelength-multiplexed wave device, and FIG. 11 shows the transmission intensity spectrum of port 0 and ports 1 to 8 in the wavelength-wavelength-multiplexed wave device. As shown in this graph, the transmission characteristics between ports 0 and 1 (FIG. 11) have the maximum transmittance at the center wavelength for port 1 and an isolation of -40 dB or more for the center wavelength of the other ports. have. Similarly, the transmission characteristics between ports 0 and 2 (FIG. 11) are such that the transmittance is maximum at the center wavelength with respect to port 2 and the isolation is -40 dB or more with respect to the center wavelength of the other ports. -3 transmission characteristics (of FIG. 11)
Has the maximum transmittance at the center wavelength for port 3, has an isolation of −40 dB or more with respect to the center wavelength of the other ports, and has a transmission characteristic between ports 0 and 4 (FIG. 11) The transmittance is maximum at the center wavelength, and-for the center wavelength of other ports.
It is confirmed that it has an isolation of 40 dB or more.

Accordingly, the pump light source corresponding to the center wavelength λ1 of the port is connected to the port P1 of the 1 × 2 port Mahach-Zehnder multi-wavelength multi-wave device 4 in FIG. The center wavelength λ of the rear 1 × 2 port Maha-Zehnder multi-wavelength wavelength-multiplexed wave port 4 is connected to port P2 of the same port.
When the pumping light source corresponding to 2 is connected and the EDF is backward pumped, the forward pumping light pumps the EDF, and the residual pumping light passes through the WDM coupler 12 on the backward pumping side to the rear Mach-Zehnder type multi-wavelength optical device 4. Since the light arrives and exits from the port of the multiplexer 4 to which the excitation light source 3 is not connected, the rear excitation light source 3 is not adversely affected. Conversely, ED
The residual pumping light of the backward pumping light that does not pump F reaches the front Mach-Zehnder multi-wavelength multiplexer 4 through the WDM coupler 10 on the forward pumping side, and the pumping light source 2 in the multiplexer 4 is not connected. The light exits from the port and does not adversely affect the excitation light source 2 ahead.

(Embodiment 2) A second embodiment of the bidirectional pumping optical amplifier according to the present invention will be described with reference to FIG. The basic configuration of the optical amplifier shown in FIG. 2 is the same as that shown in FIG. The only difference is that the Mahachender type
× 4 ports, and a front pump light source (semiconductor LD with FBG) 2 connected to the ports P1 and P3 is connected to the front Mach-Zehnder type wavelength-multiplexed wave device 4 at the same ports P1 and P3.
Light of wavelengths λ1 and λ3 is input to the rear side, and a rear pumping light source (semiconductor LD with FBG) 3 connected to the ports P2 and P4 is applied to the rear Mach-Zehnder type wavelength-multiplexed wave modulator 4 to the ports P2 and P4. Wavelengths λ2, λ4 (all wavelengths λ1,
(λ2, λ3, and λ4 are different). In this case, the light (λ1, λ3) input to P1 and P3 of the front Mach-Zehnder multi-wavelength multiplexer 4 is multiplexed by the multiplexer 4 and the port of the rear Mach-Zehnder multi-wavelength multiplexer 4 is connected. The lights (λ2, λ4) input to P2 and P4 are multiplexed by the multiplexer 4, and are multiplexed via a front multiplexer (WDM coupler) 10 and a rear multiplexer (WDM coupler) 12, respectively. E injected into EDF
The DF is excited, and each residual excitation light is emitted from an empty port of the Mach-Zehnder multi-wavelength multiplexer 4 on the side opposite to the emission side.

(Embodiment 3) A third embodiment of a bidirectional pumping optical amplifier according to the present invention will be described with reference to FIG. The basic configuration of the optical amplifier shown in FIG. 3 is the same as that shown in FIG. The difference is that the wavelengths λ1, λ2, λ3, λ4 of the pump light oscillated by the respective pump light sources 2, 3 are λ1, λ3 <λ2,
The relationship of λ4, that is, the short-wavelength pumping light is arranged on the forward pumping side and the long-wavelength pumping light is arranged on the backward pumping side. Thereby, low noise and high saturation output characteristics can be obtained. Also in this case, each of the residual pump light of the forward pump light and the backward pump light is emitted from an empty port of the Mahachender-type multi-wavelength multiplexer 4 on the side opposite to the emission side. The wavelengths λ1, λ2, λ3, λ4 of the light oscillated from the respective excitation light sources 2, 3 are λ1 <λ2 <λ3 <λ
The relationship of 4, ie, the forward pumping wavelength and the backward pumping wavelength can be set so as to be alternately arranged.

(Embodiment 4) A fourth embodiment of a bidirectional pumping optical amplifier according to the present invention will be described with reference to FIG. The basic configuration of the optical amplifier shown in FIG. 4 is the same as that shown in FIG. The difference is that the residual pump light emitted from the ports P2 and P4 of the front Mach-Zehnder type multi-wavelength optical device 4 is received by the light receiving element 21 connected to the ports P2 and P4 and monitored to monitor the excitation light. That is, the state is detected, and the level of the backward pumping light is adjusted via the control circuit 22 based on the detection result, so that a predetermined amplification state is maintained.

In FIG. 4, both the residual pumping light emitted from the ports P2 and P4 of the front Mach-Zehnder type multi-wavelength wavelength monitor 4 are monitored.
May be monitored only one of the residual excitation light emitted from the. Further, it is also possible to monitor the residual pump light emitted from the ports P1 and P3 of the rear Mach-Zehnder type multi-wavelength optical device 4, and adjust the level of the forward pump light accordingly. Further, the residual pump light emitted from both the front and rear Mahachender type multi-wavelength wave filters 4 is monitored,
The levels of the excitation light can be adjusted accordingly.

[0040]

The first bidirectional pumping light amplifier of the present application uses an LD module with an FBG as a pumping light source, injects pumping light from the pumping light source into the EDF through a Mach-Zehnder type wavelength-multiplexed wave device, Further, since the excitation light from the forward excitation light source and the excitation light from the rear excitation light source have different wavelengths, the following effects are obtained. (1) Each of the residual pump light of the forward pump light and the backward pump light is
Since the light is emitted from an empty port of the Mach-Zehnder multi-wavelength duplexer on the side opposite to the emission side, the output of the pump light source is not unstable or damaged without inserting an optical isolator. (2) Since an optical isolator is unnecessary, there is no insertion loss of the optical isolator. (3) Pump light generated from a semiconductor module with an FBG can be multiplexed at high density and used efficiently for pumping an amplification optical fiber, and the output of an optical amplifier can be increased.

In the second and third bidirectional pumping light amplifiers of the present application, the front and rear pumping light sources are two or more, and the pumping lights emitted from each pumping light source are all different wavelengths.
In addition to the above effects, pump lights of different wavelengths can be wavelength-multiplexed by a Mach-Zehnder type multi-wavelength multiplexer to obtain a higher-level pump light, and the output from the optical amplifier can be increased. There is also an effect that can be done.

The fourth bidirectional pumping optical amplifier of the present application is:
Since the longest wavelength of the light oscillated by the light emitting element of the forward pumping light source is shorter than the shortest wavelength of the light oscillating by the light emitting element of the rear pumping light source, in addition to the above-described effects, high-output, low-noise light There is also an effect that an amplifier can be realized.

In the fifth and sixth bidirectional pumping optical amplifiers of the present application, a Mach-Zehnder type multi-wavelength optical multiplexer and a semiconductor module with an FBG are used at 1480 nm or 980 nm which are most commonly used in this type of optical amplifier. Since it corresponds to the nearby excitation band, in addition to the above-mentioned effects, there is also an effect that the use range is wide.

The seventh bidirectional pumping optical amplifier of the present application is:
Since the level of the residual pump light emitted from the empty port of the Mahzender-type multi-wavelength multi-wavelength device can be monitored, in addition to the above effects, it is possible to obtain the amplification state of the optical fiber amplifier and other necessary information. There is also an effect.

The eighth bidirectional pumping optical amplifier of the present application is:
By monitoring the level of the residual pump light emitted from an empty port of the Mach-Zehnder multi-wavelength optical multiplexer, and adjusting the level of the forward pump light source and / or the backward pump light source based on the result, an optical fiber amplifier is provided. Is controlled, so that in addition to the above effect, there is also an effect that the amplification level of the optical fiber amplifier can be always maintained at a predetermined level.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of a bidirectional pumping optical amplifier according to the present invention.

FIG. 2 is an explanatory diagram showing a second embodiment of the bidirectional pumping optical amplifier of the present invention.

FIG. 3 is an explanatory view showing a third embodiment of the bidirectional pumping optical amplifier according to the present invention.

FIG. 4 is an explanatory view showing a fourth embodiment of the bidirectional pumping optical amplifier according to the present invention.

FIG. 5 is an explanatory diagram showing an example of a conventional bidirectional pumping optical amplifier.

FIG. 6 is an explanatory diagram showing another example of a conventional bidirectional pumping optical amplifier.

FIG. 7 is an explanatory diagram showing a basic structure of an LD module with an FBG.

FIG. 8 is a graph comparing output spectra of an LD module with FBG and a normal LD module.

FIG. 9A is an explanatory diagram showing a basic structure of a Mach-Zehnder multi-wavelength multiplexer, and FIG. 9B is a graph showing a transmission intensity spectrum of the multiplexer shown in FIG.

FIG. 10 is an explanatory diagram showing a basic structure of a 1 × 8-port Mahachender type wavelength-multiplexed wave device.

11 is a graph showing a transmission intensity spectrum of the multiplexer shown in FIG.

[Explanation of symbols]

 2 forward pumping light source 3 backward pumping light source 4 Mahachender wavelength multi-wave device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F072 AB09 AK06 HH02 HH03 JJ04 KK07 PP07 RR01 YY17 5K002 AA06 BA02 BA05 BA13 CA10 CA13 DA02 DA04 EA05 FA01

Claims (8)

[Claims] A bidirectional pump light amplifier for pumping an amplification optical fiber (EDF) from the front with pump light from a forward pump light source (2) and pumping from the back with pump light from a backward pump light source (3), The two pumping light sources (2, 3) are semiconductor laser diode modules (LD modules with FBG), and the pumping light generated from each of the pumping light sources (2, 3) is amplified through a Mach-Zehnder type wavelength-multiplexed wave device (4). A bidirectional pump light amplifier, which supplies an optical fiber (EDF) and emits pump light having different wavelengths from a front pump light source (2) and a rear pump light source (3). 2. A bidirectional pump light amplifier for pumping an amplification optical fiber (EDF) from the front with pump light from a forward pump light source (2) and pumping from behind with pump light from a backward pump light source (3). The two pumping light sources (2, 3) are semiconductor laser diode modules (LD modules with FBG), and the pumping light generated from each of the pumping light sources (2, 3) is amplified through a Mach-Zehnder type wavelength-multiplexed wave device (4). An optical fiber (EDF) is supplied, and two or more of each of the forward pumping light source (2) and the backward pumping light source (3) are provided, and pumping lights of different wavelengths are emitted from all of the four or more pumping light sources (2, 3). And a bidirectional pumping optical amplifier. 3. A bidirectional pumping light amplifier for pumping an amplification optical fiber (EDF) from the front with pumping light from a forward pumping light source (2) and pumping from behind with pumping light from a backward pumping light source (3), The two pumping light sources (2, 3) are semiconductor laser diode modules (LD modules with FBG), and the pumping light generated from each of the pumping light sources (2, 3) is amplified through a Mach-Zehnder type wavelength-multiplexed wave device (4). An optical fiber (EDF) is supplied, and two or more of each of the forward pumping light source (2) and the backward pumping light source (3) are provided, and the wavelengths of the pumping light emitted from the four or more pumping light sources (2, 3) are all A bidirectional pumping light amplifier, which is different in wavelength and has a wavelength in which forward pumping light and backward pumping light are alternately arranged. 4. A bidirectional pumping light amplifier for pumping an amplification optical fiber (EDF) from the front with pumping light from a forward pumping light source (2) and pumping from behind with pumping light from a backward pumping light source (3). The two pumping light sources (2, 3) are semiconductor laser diode modules (LD modules with FBG), and the pumping light generated from each of the pumping light sources (2, 3) is amplified through a Mach-Zehnder type wavelength-multiplexed wave device (4). An optical fiber (EDF) is supplied, and two or more forward pumping light sources (2) and two or more backward pumping light sources (3) are provided. The wavelengths of the pumping light emitted from the four or more pumping light sources (2, 3) are all different. A bidirectional pumping light amplifier, wherein the longest wavelength of the forward pumping light is shorter than the shortest wavelength of the backward pumping light. 5. The bidirectional pumping optical amplifier according to claim 1, wherein the wavelength-multiplexed Mach-Zehnder multi-wave device (4) and the semiconductor laser diode module (LD module with FBG) have a wavelength of 1480 nm. A bidirectional pumping optical amplifier corresponding to a nearby pumping band. 6. A bidirectional pumping optical amplifier according to claim 1, wherein the wavelength-multiplexed Maha-Zehnder multi-wavelength optical device and the semiconductor laser diode module (LD module with FBG) have a wavelength of 980 nm. A bidirectional pumping optical amplifier corresponding to a nearby pumping band. 7. The bidirectional pumping optical amplifier according to claim 1, wherein the level of the residual pumping light emitted from an empty port of the Mach-Zehnder multi-wavelength multiplexer (4) can be monitored. And a bidirectional pumping optical amplifier. 8. The bidirectional pumping optical amplifier according to claim 1, wherein the level of the residual pumping light emitted from an empty port of the Mahachender wavelength multiplexing wave monitor is monitored. A bidirectional pumping optical amplifier characterized in that the level of one or both of the front pumping light source (2) and the rear pumping light source (3) is adjusted based on the monitoring result to control the amplification level of the EDF.