JP3519926B2 - WDM optical communication system and its optical amplifier - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a WDM optical communication system for performing communication using WDM signal lights having a plurality of different wavelengths and an optical amplifier thereof .

[0002]

2. Description of the Related Art With the development of the information society, the amount of communication information tends to increase exponentially, and high-speed and large-capacity optical fiber communication has become a necessary and indispensable subject. In recent years, an optical amplifier (EDFA) using, for example, an erbium-doped optical fiber has been used as an approach to increase the speed and capacity.
1550 nm wavelength band (generally about 1530 to 156
(0 nm) optical signal is amplified to increase the capacity of the signal light itself, and the transmission method is being studied. Optical transmission (optical communication) systems such as wavelength division multiplexing (WDM) transmission are being studied. . The wavelength division multiplexing optical communication is a method of transmitting (communication) optical signals having different wavelengths through one optical fiber. Incidentally, conventionally, an optical fiber for optical transmission has a wavelength of 1.5.
A dispersion shift fiber (DSF) having a zero dispersion wavelength in the 5 μm band is used and is widely installed.

[0003]

However, as described above, when a plurality of signal lights having different wavelengths are incident on the optical fiber, four wave mixing (FWM) occurs. This four-wave mixing is caused by the nonlinear characteristics of the optical fiber between channels (signal lights of different wavelengths).
Is a phenomenon in which light of a new wavelength is generated, and for example, in FIG. 6, four-channel signal light (signal light of two different wavelengths) that is generated when light enters the optical fiber 2. An example of lightwave mixing is shown.

[0004] For example, reference (1) AR Chraplyvy
et al., J. Lightwave Tech., 13 (1995) p84
1. As shown in FIG. 3, the optical frequency f _F of the generated FWM light is f _F = 2f _i −f _j or f _F = 2f _j −, where the optical frequencies of the original two channels are f _i and f _j. f _i .
The intensity of FWM light is represented by the following equation (1).

[0005]   P_F(L) = (1024π⁶/ N^Fourλ²c²) (3X_Fijk)²{P_i(0) P_j(0) ² / Aeff}²(E^{- α L}) {(1-e^{- α L})²/ Α²} {Α²/ Α²+ Δβ²} [1 + {4e^{- α L}sin²(ΔβL / 2) / {1-exp (-αL)}²]… (1)

In the equation (1), Δβ = (2πλ ²
/ C) (Δf ² ) {D + Δf (λ ² / C) (dD / d
λ)}, n is the refractive index of the core, λ is the wavelength of the FWM light, X _Fijk is the third-order nonlinear susceptibility tensor of the optical fiber, Aeff is the effective area, α is the attenuation constant of the fiber,
L is a fiber length, P _i and P _j are input light intensities, Δf is a wavelength interval of wavelengths, D is chromatic dispersion, and C is a light velocity.

The number M of four-wave mixing light generated when N-channel signal light is incident on the optical fiber is M
= 1/2 (N ³ −N ² ) and the number of signal light channels,
That is, as the number of wavelengths increases, the number of generated four-wave mixed lights rapidly increases, and the generated four-wave mixed lights interact with the original signal light to deteriorate the signal light. Therefore, when performing wavelength-division-multiplexed optical communication using the dispersion-shifted fiber having the zero-dispersion wavelength in the wavelength 1.55 μm band,
Four-wave mixing is a major factor limiting the expansion of transmission capacity by wavelength division multiplexing communication.

The present invention has been made to solve the above problems, and an object of the present invention is to generate four-waves when wavelength-multiplexed signal lights having a plurality of different wavelengths are incident on an optical fiber for optical transmission. Provided is a wavelength division multiplexing optical communication system and an optical amplifier thereof capable of suppressing the mixing, thereby increasing the number of wavelengths (the number of channels) of the wavelength division multiplexing signal light and expanding the transmission capacity. To do.

[0009]

In order to achieve the above object, the present invention has the following constitution as means for solving the problem. That is, the first aspect of the present invention is a wavelength-multiplexed signal light source that emits wavelength-multiplexed signal light having at least two different wavelengths in a wavelength band of about 1570 to 1600 nm, and a wavelength deviated from the wavelength of the wavelength-multiplexed signal light. A 1.55 μm band zero-dispersion optical fiber having a zero-dispersion wavelength in the 1.55 μm band and transmitting the wavelength-division-multiplexed signal light, and a wavelength of about 1.55 μm band zero-dispersion optical fiber
Dispersion compensation that compensates chromatic dispersion from 70 to 1600 nm
A structure having an optical fiber and an optical amplifier for amplifying the wavelength-multiplexed signal light is a means for solving the problem.

The second aspect of the present invention has a wavelength of about 1570-
At least two different wavelength bands up to 1600 nm
Wavelength multiplexed signal light emitting wavelength multiplexed signal light having a wavelength
Source and wavelength 1.5 deviating from the wavelength of the wavelength division multiplexed signal light
It has a zero-dispersion wavelength in the 5 μm band and transmits the wavelength multiplexed signal light.
A 1.55 μm band zero dispersion optical fiber for transmission and
And an optical amplifier for amplifying the multiple signal light.
WDM optical communication system in which the optical amplifier
Erbium-doped optical fiber that amplifies heavy signal light,
A wavelength of 1480 nm for exciting a bium-doped optical fiber
And an excitation light source that emits excitation light.
Erbium concentration and optical fiber length of um-doped optical fiber
Excitation of the excitation light source by setting the product of
The structure having a light intensity of 300 mW or more is used as a means for solving the problem.

Further, the third invention is the same as the first invention.
On having the configuration, the optical amplifier has a doped optical fiber for amplifying a wavelength-multiplexed signal light and a pumping light source which emits a pumping light of wavelength 1480nm band that excites the erbium-doped optical fiber, the product of erbium concentration and fiber length of the erbium-doped optical fiber 600
And 00ppm · m or more, and a means for solving the problems with the configuration in which the excitation light intensity of the excitation light source and more than 300 mW. Further, a fourth invention is the above-mentioned second or
In addition to the third invention, the optical amplifier is erbium-doped.
A population inversion control for adjusting the population inversion in the optical fiber
Configuration that further includes a control light source that emits light
Is used as a means to solve the problem. Furthermore
The fifth invention relates to an optical amplifier, which has a wavelength of about 1570 to 1.
Has at least one wavelength in the wavelength band up to 600 nm
An optical amplifier for amplifying the wavelength division multiplexed signal light,
The optical amplifier is an erbium that amplifies wavelength multiplexed signal light.
Pump the doped optical fiber and the erbium-doped optical fiber
And a pumping light source that emits pumping light in the 1480 nm wavelength band.
Erbium of the erbium-doped optical fiber
Product of optical density and optical fiber length is 60,000 ppm · m or more
And the excitation light intensity of the excitation light source is 300 mW or more.
The configuration is used as a means for solving the problem.
Furthermore, a sixth invention is provided with the configuration of the fifth invention.
In the optical amplifier, the inversion in the erbium-doped optical fiber
Inversion distribution control that adjusts the distribution
Solving the problem with a configuration that further has a trawl light source
It is a means to

In the present invention having the above structure, the wavelength is about 157.
The wavelength multiplexed signal light in the wavelength band from 0 to 1600 μm is
It is sufficiently amplified by the optical amplifier and transmitted through a 1.55 μm band zero dispersion optical fiber having a zero dispersion wavelength in the wavelength 1.55 μm band deviated from the wavelength of the wavelength multiplexed signal light.

The four-wave mixing that occurs when the wavelength-multiplexed signal light is incident on the optical fiber is the intensity of the four-wave mixing light when the wavelength of the wavelength-multiplexed signal light and the zero dispersion wavelength of the optical fiber are equal. Grows larger. This is clear from the examination results shown below.

That is, in the equation (1), η is represented by the equation (2), where η is a portion to which the wavelength dispersion D contributes.

Η = {α ² / (α ² + Δβ ² )} [1+ {4e ^{− α l} sin ² (ΔβL / 2)} {1-exp (-αL)} ² ] ... (2)

Based on the equation (2), when each parameter is set as shown in (Table 1) and η is plotted, it becomes as shown in FIG.

[0017]

[Table 1]

As is apparent from FIG. 5, when the value of chromatic dispersion D is larger than 10 ps / nm / km, the value of η becomes almost 0, and when the value of chromatic dispersion D approaches 0, the value of η becomes sharp. Grows to. Therefore, when the zero-dispersion wavelength of the wavelength-multiplexed signal light and the zero-dispersion wavelength of the optical fiber for optical transmission are substantially equal to each other and the chromatic dispersion is close to 0, the four-wave mixing intensity becomes large.

The wavelength of 1.55 μm band, 1570 to 1
Η when two channels of light are incident in the 600 nm band
Are shown in (Table 2). The parameters are as shown in Table 1, the zero dispersion wavelength was 1550 nm, and the dispersion curve was linearly approximated with a dispersion slope of 0.08 ps / nm ² / km.

[0020]

[Table 2]

As can be seen from Table 2, the wavelength is 1.55 μm.
The FWM generation efficiency is remarkably suppressed by transmitting the wavelength-multiplexed signal light having the wavelength of 1570 to 1600 nm to the DSF having the zero dispersion wavelength at 1550 nm.

In the present invention, as described above, the wavelength of the wavelength division multiplexed signal light is set to about 1570 to 1600 nm, and the wavelength division multiplexed signal light is deviated from the wavelength of the wavelength division multiplexed signal light by 1.55 μm.
Since it is incident on a 1.55 μm band zero dispersion optical fiber having a zero dispersion wavelength in the m band, it is possible to suppress the intensity of the four-wave mixing light, and the wavelength is about 1570 to 16
In order to amplify the wavelength-multiplexed signal light up to 00 nm to a sufficient light intensity by the optical amplifier, four-wave mixing is suppressed, and
It becomes possible to perform wavelength-multiplexed optical communication by using wavelength-multiplexed signal light having sufficient light intensity, and the above problem is solved.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a wavelength division multiplexing optical communication system according to the present invention. As shown in the figure, the wavelength division multiplexing optical communication system of the present embodiment example has at least two wavelength bands in the wavelength range of about 1570 to 1600 nm.
A wavelength-multiplexed signal light source 3 for transmitting wavelength-multiplexed signal light having two different wavelengths (for example, 8 channels) and a wavelength-multiplexed signal having a zero dispersion wavelength in a wavelength band of 1.55 μm deviated from the wavelength of the wavelength-multiplexed signal light. 1.55 μm for transmitting light
Dispersion shift fiber 2 as zero-dispersion optical fiber
And an optical amplifier 1 for amplifying the wavelength-multiplexed signal light, and the wavelength-multiplexed signal light source 3 is provided on the incident side of the optical amplifier 1.
Are connected.

The wavelength-multiplexed signal light source 3 may be composed of, for example, a light source that has a plurality of DFB (Distriduted FeedBack) lasers of different wavelengths and combines the output light from the DFB laser with an optical multiplexer to emit the light. However, it may be configured by a light source that extracts a plurality of narrow band lights from the output light of the wide band spectrum light source by a narrow band filter and transmits them. The dispersion slope of the dispersion shift fiber 2 used in this embodiment is 0.08 ps / nm ² / km.

As shown in FIG. 2, the amplifier 1 has an erbium-doped optical fiber 5 that amplifies the wavelength-division multiplexed signal light, and WDM (EDM) is provided on the incident side and the emission side of the erbium-doped optical fiber 5, respectively. Wavelength Divisiosn Multipl
ex) Pumping light sources 6a and 6b that emit pumping light in a wavelength band of 1480 nm that pumps the erbium-doped optical fiber 5 are connected to the optical isolators 8a and 8b via the couplers 9a and 9b. In the figure, reference numeral 11 denotes a connecting optical fiber, and the control light source 10 is connected to the incident side of the optical isolator 8a via a multiplexer 13.

The control light source 10 is a light source that emits population inversion control light for adjusting population inversion in the erbium-doped optical fiber 5, and has a wavelength of about 1570 to 160.
It is provided to suppress a gain deviation (a value obtained by subtracting the gain of the signal light having the minimum gain from the gain of the signal light having the maximum gain in the wavelength division multiplexed signal lights) in the wavelength band up to 0 nm. . Further, in the present embodiment example, the excitation light source 6
The excitation light intensity of a and 6b is about 1000 mW, the erbium concentration of the erbium-doped optical fiber 5 is 700 ppm,
The length is 150 m, so that the product of the erbium concentration of the erbium-doped optical fiber 5 and the optical fiber length is 10 m.
It is 5000ppm · m.

FIG. 3 shows an example of the optical amplification characteristic of the optical amplifier 1 used in the wavelength division multiplexing optical communication system of the present embodiment, in which the intensity of the control light emitted from the control light source 10 is 0 dBm. And a wavelength of about 1570 to 1
Intensity -20 dBm with 8 different wavelengths of 600 nm
The gain of the output light when the wavelength-multiplexed signal light of 1 is amplified by the optical amplifier 1 and output is shown. As is clear from the figure, each wavelength of the wavelength division multiplexed signal light has a gain of about 30 dB / c.
The gain deviation is 0.9 dB and the gain deviation is 0.9 dB. As described above, the optical amplifier 1 used in the present embodiment is an optical amplifier capable of performing optical amplification with practically sufficient gain and gain deviation.

The example of the present embodiment is configured as described above, and the wavelength of light emitted from the wavelength-multiplexed signal light source 3 is about 1570.
The wavelength-multiplexed signal light in the wavelength band up to 1600 nm is amplified by the optical amplifier 1 with sufficient gain and gain deviation, and propagates through the dispersion shift fiber 2.

Then, in this embodiment, the dispersion-shifted fiber 2 has a zero dispersion wavelength at a wavelength of 1570 nm, and the dispersion slope is 0.08 ps / nm ² / km. The wavelength dispersion at 1570 nm is 1.6 ps / nm ² / km, which is obtained by the above equation (2).
Therefore, η at the wavelength of 1570 nm is about η = 0.06, and the chromatic dispersion D of the dispersion shift fiber is larger than 1.6 ps / nm ² / km on the longer wavelength side than the wavelength of 1570 nm. The value becomes even smaller, which suppresses the generation of four-wave mixing light.

In order to suppress the four-wave mixed light, for example, in Japanese Patent Laid-Open No. 7-107069, when an optical fiber is used and optical signals of a plurality of channels having different wavelengths are multiplexed and transmitted, A guard band for suppressing four-wave mixing with a predetermined bandwidth including the zero-dispersion wavelength of the optical fiber is installed, and the signal light of multiple channels to be multiplexed is placed on either the short wavelength side or the long wavelength side outside the guard band. The configuration is shown to be configured for installation at.
However, the conventional optical amplifier for wavelength division multiplexing optical communication is
The amplification wavelength band capable of gain flattening is about 1545 to 1
It is limited to 565 nm, and even if an attempt is made to apply wavelength-division-multiplexed light in a wavelength band that avoids the vicinity of the zero-dispersion wavelength of a dispersion-shifted fiber to a wavelength-division-multiplexed optical communication system, the wavelength-division-multiplexed signal light in that wavelength band is used in a conventional optical amplifier However, in the case of amplification by, the practically sufficient gain and gain deviation could not be obtained.

For example, when it is desired to transmit 16-channel wavelength-multiplexed signal light with a wavelength interval of 0.8 nm, at least 12
A signal wavelength band of nm is required, but if the zero-dispersion wavelength of the dispersion-shifted fiber is 1555 nm, avoid this wavelength band and apply the wavelength-multiplexed signal light of, for example, 1560 nm to 1572 nm to the wavelength-multiplexed optical communication system. Even if the wavelength division multiplexed signal light in this wavelength band is
Since it cannot be sufficiently amplified by an optical amplifier of 545 to 1565 nm, it is not possible to construct a wavelength division multiplexing optical communication system that is practical.

On the other hand, in the present embodiment, the optical amplifier 1 is the optical amplifier having the above-mentioned configuration, whereby the wavelength of about 15 is obtained.
The wavelength-multiplexed signal light in the wavelength band from 70 to 1600 nm is sufficiently amplified by the optical amplifier 1, amplified with a gain and gain deviation sufficient for practical use, and then the wavelength-multiplexed signal light is incident on the dispersion shift fiber 2 and transmitted. Therefore, a highly reliable wavelength division multiplexing optical communication system can be realized.

FIG. 4 shows a second embodiment of the wavelength division multiplexing optical communication system according to the present invention. The example of the present embodiment is configured almost the same as the example of the first embodiment, and the characteristic of the example of the present embodiment different from the example of the first embodiment is that
A dispersion compensating optical fiber 4 is provided between the wavelength-division multiplexed signal light source 3 and the optical amplifier 1 for compensating the chromatic dispersion of the dispersion shift fiber 2 in the wavelength range of about 1570 to 1600 nm.

This embodiment also operates in the same manner as the first embodiment and can achieve the same effect.

Further, in the present embodiment, the dispersion compensating optical fiber 4 is provided, and the dispersion compensating optical fiber 4 compensates for the chromatic dispersion of the dispersion shift fiber 2 in the wavelength range of about 1570 to 1600 nm. Since the optical distortion can be suppressed, in addition to the effect of suppressing the four-wave mixing similar to that of the above-described first embodiment, the effect of suppressing the distortion due to wavelength dispersion can be achieved, and the optical transmission speed can be further increased. Can be realized.

The present invention is not limited to the above-mentioned embodiments, but can take various modes. For example,
In the above embodiment, the erbium-doped optical fiber 5 of the optical amplifier 1 has an erbium concentration of 700 ppm and a length of 150.
However, the erbium concentration and the length of the erbium-doped optical fiber 5 are not particularly limited and may be set appropriately. For example, the product of the erbium concentration and the optical fiber length is 60,000 ppm · m or more. By doing
Since it has been confirmed by experiments by the present applicant that the low gain coefficient of the erbium-doped optical fiber at a wavelength of about 1570 to 1600 nm can be supplemented and the gain can be increased, the erbium concentration and the optical fiber length of the erbium-doped optical fiber 5 By setting the product of 60000 ppm · m or more, the same effect as that of the above-described embodiment can be obtained.

Further, in the above embodiment, the pumping light intensity of the pumping light sources 6a and 6b of the optical amplifier 1 is set to 1000 mW, but the intensity of the pumping light sources 6a and 6b is not particularly limited and may be set appropriately. It is a thing. However, by setting the pumping light intensity of the pumping light sources 6a and 6b to 300 mW or more, the gain up to the wavelength of about 1570 nm to 1600 nm can be easily and surely increased by the optical amplifier 1. Therefore, the pumping light sources 6a and 6b Excitation light intensity of 300mW
The above is preferable.

Further, the structure of the optical amplifier applied to the wavelength division multiplexing optical communication system of the present invention is not particularly limited and may be set appropriately. For example, an optical amplifier using an erbium-doped optical fiber is used. When configured, an optical amplifier capable of compensating for the low gain coefficient of the wavelength band up to about 1570 nm to 1600 nm of the erbium optical fiber and obtaining a sufficient gain characteristic in the same wavelength band may be used.

[0039]

According to the present invention, wavelengths of about 1570 to 16 are obtained.
An optical amplifier for amplifying the wavelength-division-multiplexed signal light in the wavelength band of 00 nm is provided to sufficiently amplify the wavelength-division-multiplexed signal light, and the signal light is set to a 1.55 μm band deviated from the wavelength of the wavelength-division-multiplexed signal light with a zero dispersion wavelength. Since the transmission is performed using the existing 1.55 μm band zero dispersion optical fiber, four-wave mixing is suppressed by setting the wavelength band of the wavelength division multiplexed signal light and the wavelength different from the zero dispersion wavelength of the optical fiber for optical transmission, Moreover, it is possible to construct a highly reliable wavelength-multiplexed optical communication system by using the wavelength-multiplexed signal light having sufficient intensity.

Further, according to the present invention, which is provided with a dispersion compensating optical fiber for compensating the chromatic dispersion of the wavelength of about 1570 to 1600 nm of the 1.55 μm band zero dispersion optical fiber, the 1.55 μm band is provided by the dispersion compensating optical fiber. Since it is possible to compensate the wavelength dispersion of the zero dispersion optical fiber up to the wavelength of about 1570 to 1600 nm, it is possible to suppress the distortion due to the wavelength dispersion of the wavelength division multiplexed signal light. It is possible to suppress the signal light distortion due to dispersion and to provide a more reliable and excellent wavelength division multiplexing optical communication system capable of speeding up.

The optical amplifier further comprises an erbium-doped optical fiber for amplifying the wavelength-division-multiplexed signal light, a pumping light source for pumping pumping light having a wavelength of 1480 nm for pumping the erbium-doped optical fiber, and an inversion distribution in the erbium-doped optical fiber. And a control light source that emits population inversion control light for adjusting the optical density. The product of the erbium concentration of the erbium-doped optical fiber and the optical fiber length is 60000 pp.
According to the present invention in which the pump light intensity of the pump light source is 300 mW or more, the low gain coefficient of the wavelength of about 1570 to 1600 nm of the erbium-doped optical fiber is compensated by the population inversion control light from the control light source. Since an optical amplifier that can easily and surely obtain sufficient gain and gain deviation in the wavelength band can be obtained, by applying this optical amplifier, it is possible to easily and surely A high-quality WDM optical communication system can be put to practical use.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram showing a first embodiment of a wavelength division multiplexing optical communication system according to the present invention.

FIG. 2 is a configuration diagram showing an optical amplifier applied to the embodiment example.

3 is a graph showing an example of wavelength-multiplexed signal light amplification characteristics by the optical amplifier shown in FIG.

FIG. 4 is a main part configuration diagram showing a second embodiment of the wavelength division multiplexing optical communication system according to the present invention.

FIG. 5 is a graph showing the relationship between the intensity characteristic of four-wave mixed light generated by the nonlinear optical characteristic of an optical fiber and the chromatic dispersion.

FIG. 6 is a graph showing an example of four-wave mixing light generated when signal lights having two different wavelengths are incident on an optical fiber.

[Explanation of symbols]

1 Optical amplifier 2 Dispersion shifted fiber 3 WDM signal light source 4 Dispersion compensating optical fiber 5 Erbium-doped optical fiber 6a, 6b Excitation light source 9a, 9b WDM coupler 10 control light source

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-110517 (JP, A) JP-A-2-272523 (JP, A) JP-A-9-92918 (JP, A) Sakamoto Tadashi et al., 1580 nm Band-Wavelength Multiplexing Technology (I): Expansion of wavelength range and suppression of four-wave mixing, Proceedings of IEICE Communications Society Conference 2, Japan, The Institute of Electronics, Information and Communication Engineers, August 1997 13th, B-10-78, p.377 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04J 14/00-14/08 H04B 10/00-10/28 G02F 1/35

Claims (6)

(57) [Claims] 1. A wavelength-multiplexed signal light source for transmitting wavelength-multiplexed signal light having at least two different wavelengths in a wavelength band of about 1570 nm to 1600 nm, and a wavelength of 1.55 μm deviated from the wavelength of the wavelength-multiplexed signal light.
A 1.55 μm band zero-dispersion optical fiber having a zero-dispersion wavelength in the band and transmitting the wavelength-multiplexed signal light, and a wavelength of about 1570 of the 1.55 μm-band zero-dispersion optical fiber
Dispersion compensating optical fiber for compensating chromatic dispersion up to 1600 nm
And Aiba, wavelength multiplexing optical communication scheme characterized by having an optical amplifier for amplifying the wavelength multiplexed signal light. 2. A wave having a wavelength of about 1570 to 1600 nm.
Wavelength multiplex with at least two different wavelengths in the long band
A wavelength-multiplexed signal light source that emits signal light, and a wavelength of 1.55 μm deviated from the wavelength of the wavelength-multiplexed signal light
Transmits the wavelength multiplexed signal light having a zero dispersion wavelength in the band
Having a 1.55 μm band zero dispersion optical fiber and an optical amplifier for amplifying the wavelength division multiplexed signal light
A wavelength division multiplex optical communication system, wherein the optical amplifier is an erbium-based optical amplifier for amplifying the wavelength division multiplex signal light.
Wavelength of 1480 nm for exciting the optical fiber and the erbium-doped optical fiber
And an erbium concentration and an optical flux of the erbium-doped optical fiber.
Excitation with a product of fiber length of 60,000 ppm · m or more
The excitation light intensity of the light source is set to 300 mW or more.
Wavelength division multiplexing optical communication system to be. 3. The WDM optical communication system according to claim 1.
There are, the optical amplifier includes erbium doped optical fiber for amplifying a wavelength-multiplexed signal light, the wavelength excites the erbium-doped fiber 1480nm
Has an excitation light source that emits excitation light band, the product of erbium concentration and fiber length of the erbium doped optical fiber and 60000ppm · m or more, the excitation light intensity of the excitation <br/> electromotive source wavelength multiplexing optical communication scheme you characterized in that not less than 300 mW. 4. The wavelength-multiplexer according to claim 2 or 3.
It is a heavy optical communication system, The optical amplifier has a population inversion in an erbium-doped optical fiber.
Inversion distribution control to adjust light
Long-division optical communication characterized by further having a light source
method. 5. Waves having a wavelength of about 1570 to 1600 nm
Said wavelength division multiplexing signal having at least one wavelength in the long band
An optical amplifier for amplifying the signal light , wherein the optical amplifier is an erbium for amplifying the WDM signal light.
Doped optical fiber and wavelength of 1480 nm for exciting erbium-doped optical fiber
An excitation light source that emits excitation light in a band, and a product of an erbium concentration and an optical fiber length of the erbium-doped optical fiber is 60000 ppm · m or more, and an excitation light intensity of the excitation light source is 300 mW or more. An optical amplifier characterized by. 6. The optical amplifier according to claim 5, wherein: The optical amplifier has a population inversion in an erbium-doped optical fiber.
Inversion distribution control to adjust light
Optical amplifier further comprising a light source.