JP2000081643A - Wavelength multiplex optical transmission system and wavelength converter for wavelength multiplex optical transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the superposition of pumping light and signal light for wavelength conversion by offsetting the wavelength of the wavelength multiplex signal light not to be subjected to the wavelength conversion and the wavelength of the pumping light from each other and arranging these wavelengths so as not to overlap on each other. SOLUTION: When the wavelength λP of the pumping light enters the inside of the band of a system L at a wavelength conversion destination, the trouble that the signal of the wavelength λ3L not to be subjected to the wavelength conversion in the system L overlaps on the pumping light occurs and, therefore, the wavelength λP of this pumping light needs be offset from the wavelength λ3L of the signal light. More specifically, the signal light in the system C is a wavelength λ1C=1540 nm and a wavelength L2C=1600 nm and when the wavelength λ2C is converted in wavelength λ1C=1600 nm, the wavelength λP of the pumping light needs be made to 1574 nm. In such a case, the signal of the wavelength λ1C is converted into the λ2L=1610 nm. When the wavelength λP of the pumping light overlaps on the signal light not to be subjected to the wavelength conversion in the band of the system L, the wavelength thereof is offset to a wavelength which does not overlap any of the signal light not to be subjected to the wavelength conversion in the system L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength multiplexing optical transmission system with band conversion and a wavelength converter for wavelength multiplexing optical transmission for performing band conversion, and more particularly to an optical system using an erbium-doped optical fiber. It relates to wavelength conversion between bands resulting from the gain characteristics of the amplifier. The wavelength converter for transmitting wavelength division multiplexed light of the present invention can be used not only for wavelength division multiplexed signal light but also for wavelength conversion of various kinds of light.

[0002]

2. Description of the Related Art In recent years, optical amplifiers using erbium-doped optical fibers (hereinafter referred to as EDFAs) have been developed.
ler) for long-distance, large-capacity optical transmission. In this field, wavelength division multiplexing transmission (hereinafter WDM: Wavelength
A transmission method using a division multiplexing method has attracted attention as one of the promising technologies.

[0005] The EDFA has a gain band of signal light divided into three as shown in FIG. Conventionally, the short wavelength side 2
One band, from 1530nm to 1560 centered at 1550nm
Transmission experiments were mainly performed using the nm wavelength band. 1530
The band from nm to 1560 nm is sometimes called C-band. However, in 1990, British Telecom's Massicott et al. Pointed out that by optimizing the length of the erbium-doped optical fiber, the possibility of using a long wavelength band centered at 1580 nm for actual transmission was introduced. Various studies have established long-wavelength band transmission technology. In early 1998 actual transmission experiments were reported. With these technologies, WDM has found a new field in the long wavelength band (1569nm to 1610nm). This band is sometimes called L-band. In this specification, the center wavelength is used as a representative value when referring to a band in which the EDFA is known to have a gain, and in the case of FIG. 5, they are referred to as a 1530 nm band, a 1560 nm band, and a 1585 nm band.

In a conventional WDM transmission system using an EDFA, signal light channels are distributed in one or more of the three bands, or two bands on the short wavelength side are flattened from 1530 nm to 1565 nm. And two bands from 1569 nm to 1610 nm, and the signal light channels are distributed in these two bands. In the latter, the band from 1530 nm to 1565 nm is called C-band, and the band from 1569 nm to 1610 nm is L-band.
Sometimes called. Table 1 shows several examples of channels and wavelength bands of WDM systems that have been reported so far.

[0005]

[Table 1]

In a WDM system using an EDFA having a gain band as described above, a transmission system using any of the 1530 nm band, 1560 nm band, 1585 nm band, or a combination thereof will be constructed. In the future, a communication network connecting such WDM systems is also expected. For example, as shown in FIG. 7, a WDM system of wavelengths λ ₁ and λ ₂ is provided between stations S ₁ and S ₂ , communication between nodes A and C is performed using wavelength λ ₂ ,
A Node B, if the inter-C is in communication with the wavelength lambda _1, station the wavelength lambda ₁ to S ₁ to lambda _2, also by additionally installed wavelength converter for converting the wavelength lambda ₂ to lambda _1, the nodes A and station S ₁
During use the signal light of the wavelength lambda _1, and also the node B and the station S ₁
During communicate using signal light having a wavelength lambda _2, and if the wavelength converting the signal light in the wavelength converter, the node A without significant changes to the system, the like perform communication even B.

Further, as shown in FIG. 8, two independent WDMs are provided.
There is a system that operates between stations A and B in the 1550 nm band,
If it is designed to operate in the 1580 nm band between stations C and D, a wavelength converter is provided between stations B and D to extend the 1550 nm band.
If you convert 1580nm band to 1580nm band and 1550nm band,
Information can be newly shared between the stations A and D.

There are demands for wavelength converters in various places in WDM systems. One of the typical wavelength converters is one based on four-wave mixing (FWM) using nonlinearity of an optical fiber. this
The FWM wavelength converter irradiates the non-linear optical fiber with a high-intensity pump light having a frequency f _P different from the signal light having the frequency f _S to convert the signal light having the frequency f _S into a frequency f _FWM.
= And converts into frequencies 2f _P -f _S. Generally, in the WDM system, the frequency before the wavelength conversion and the frequency after the wavelength conversion are determined in advance, and the pump light is determined from them. Therefore, for example, the wavelength λ ₁₁ shown in FIG.
_In order to convert the wavelength multiplexed signal light of ₁₂ (λ ₁₂ > λ ₁₁ ) from the wavelength λ ₂₁ to the wavelength multiplexed signal light of wavelength λ ₂₂ (λ ₂₂ > λ ₂₁ > λ ₁₂ ), the phase matching condition of the FWM requires , The wavelength λ _P of the pump light is determined as follows: λ _P = 2λ ₁₂ λ ₂₁ / (λ ₁₂ + λ ₂₁ ), (1)

[0009]

In the FWM wavelength converter in which the wavelength λ _{P of the} pump light is determined by the frequencies before and after the conversion, if there is any signal light other than the signal light whose wavelength is converted in the system, this signal light May overlap with the wavelength of the pump light. For example as shown in FIG. 6, the wavelength-multiplexed signal light wavelength lambda _i -.DELTA..lambda the lambda ₁₂ wavelength _{λ 11 (λ 12> λ 11} )
Distributed within the gain band from _x to λ _i + Δλ _x , the wavelength multiplexed signal light from wavelength λ ₂₁ to wavelength λ ₂₂ (λ ₂₂ > λ ₂₁ > λ ₁₂ ) gains from wavelength λ _k −Δλ _y to λ _k + Δλ _y If distributed in the band and there is another signal light between λ _k −Δλ _y and λ ₂₁ , the wavelength λ _{P of the} pump light is λ _k −Δλ _y ≦ λ _P ≦ λ ₂₁ , There is a high possibility that the pump light and the signal light overlap. If the pump light and the signal light overlap, the transmission performance of the signal light may be degraded.

[0010] In addition, the conventional wavelength conversion has always been performed in the band conversion in the C-band, and the wavelength conversion that fully utilizes the band of the EDFA expanded to the L-band has not been performed. .

[0011]

In the WDM transmission shown in FIG. 6, of the wavelength division multiplexed signal light distributed in the wavelength band λ _i −Δλ _x to λ _i + Δλ _x , the wavelength division multiplex signal light has a wavelength λ ₁₁ to λ ₁₂ (λ ₁₁ <
λ ₁₂ ) is changed from another wavelength band λ _k -Δλ _y to λ
or wavelength conversion using the FWM between the _k + [Delta] [lambda] _y of lambda ₂₂ wavelength range from lambda ₂₁ WDM systems operating in the range (λ ₁₂ <λ _22), or when the inverse transform thereof, the pump light The wavelength λ _P must be set to the value of the above equation (1).
However, the following two cases may occur depending on how the wavelength conversion region is set. λ ₁₂ ≦ λ _P ≦ λ _i + Δλ _x (2) λ _k −Δλ _y ≦ λ _P ≦ λ ₂₁ (3) Therefore, in the case of formula (2), the wavelength region , Λ ₁₂ ≦ λ _P ≦ λ _i + Δλ _x , The wavelength of the signal light may be selected so as not to overlap with the wavelength of the pump light, and in the case of Expression (3), the wavelength region, λ _k −Δλ The wavelength of the signal light in the range of _y ≦ λ _P ≦ λ ₂₁ may be selected so as to avoid overlapping with the wavelength of the pump light.

Therefore, the wavelength division multiplexing optical transmission system according to claim 1 of the present invention provides a wavelength division multiplexing signal light of wavelengths λ ₁₁ to λ ₁₂ (λ ₁₂ > λ ₁₁ ) belonging to one of two or more different wavelength bands. And wavelengths λ ₂₁ (λ ₂₁
> Λ ₁₂ ) to the wavelength λ ₂₂ (λ ₂₂ > λ ₂₁ ) and the wavelength λ _P based on the four-wave mixing phase matching condition.
In a wavelength division multiplexing optical transmission system in which wavelength conversion is performed by a pump light of (λ _P = 2λ ₁₂ λ ₂₁ / (λ ₁₂ + λ ₂₁ )) to enable wavelength multiplex communication between different wavelength bands, the wavelength of the pump light is If the wavelength of the wavelength-division multiplexed signal light, which is not subject to the wavelength conversion, falls within the wavelength band before the conversion or the wavelength band after the wavelength conversion, the wavelength of the multiplexed signal light is shifted from the wavelength band of the pump light so that they do not overlap. is there.

According to a second aspect of the present invention, in the wavelength division multiplexing optical transmission system according to the first aspect, the wavelength of the pump light is within the wavelength band before the wavelength conversion or within the wavelength band after the wavelength conversion. In this case, the wavelength of the wavelength-division multiplexed signal light that is not subject to wavelength conversion within the wavelength band is shifted from the wavelength of the pump light, and is arranged so that both wavelengths do not overlap.

According to a third aspect of the present invention, there is provided the wavelength multiplexing optical transmission system according to the first aspect, wherein the wavelength of the pump light is within a wavelength band before the wavelength conversion or within a wavelength band after the wavelength conversion. In this case, the wavelength of the pump light is shifted from the wavelength of the wavelength-division multiplexed signal light that is not subject to wavelength conversion within the wavelength band, and is arranged so that the two wavelengths do not overlap.

According to a fourth aspect of the present invention, there is provided a wavelength division multiplexing optical transmission system according to any one of the first to third aspects, wherein a bandwidth used for wavelength conversion of each wavelength band is set. The bandwidth of the wavelength band having the narrowest band is set as a reference, and in other wavelength bands, a band other than the band used for wavelength conversion is used for communication with another wavelength division multiplexing transmission system.

According to a fifth aspect of the present invention, there is provided a wavelength division multiplexing optical transmission system according to any one of the first to third aspects of the present invention. The width is set based on the bandwidth of the wavelength band having the narrowest band, and in each wavelength band, only the band used for wavelength conversion is used.

According to a sixth aspect of the present invention, there is provided a wavelength division multiplexing optical transmission system according to any one of the first to fifth aspects.
One is the C-band which is a wavelength band from 1530 nm to 1565 nm, and the other is 1569 nm
And an L-band which is a wavelength band of 1610 nm to perform wavelength conversion between these wavelength bands.

According to a seventh aspect of the present invention, there is provided a wavelength division multiplexing optical transmission system according to any one of the first to sixth aspects, wherein two or more wavelength division multiplexing optical systems having independent wavelength conversion. The transmission is performed between transmission systems, and one or more wavelength division multiplexing optical transmission systems constitute one wavelength division multiplexing optical transmission system.

The wavelength converter for wavelength multiplexing optical transmission according to claim 8 of the present invention is a wavelength multiplexing device for wavelength multiplexing of wavelengths λ ₁₁ to λ ₁₂ (λ ₁₂ > λ ₁₁ ) belonging to one of two or more different wavelength bands. Signal light and wavelength λ ₂₁ belonging to a different wavelength band (λ ₂₁ >
between the wavelength-multiplexed signal light having a wavelength lambda ₂₂ from _{λ 12) (λ 22> λ} 21), the wavelength based on the phase matching conditions of the four-wave mixing lambda
And a wavelength conversion by the pump light _{P (λ P = 2λ 12 λ} 21 / (λ 12 + λ 21)), in the wavelength-multiplexed optical transmission wavelength converter for enabling wavelength division multiplexing communications among different wavelength bands, When the wavelength of the pump light falls within the wavelength band before the wavelength conversion or within the wavelength band after the wavelength conversion, the wavelength of the wavelength-division multiplexed signal light not subject to the wavelength conversion in the wavelength band is shifted from the wavelength of the pump light and does not overlap. It is set as follows.

According to a ninth aspect of the present invention, there is provided a wavelength multiplexing optical transmission wavelength converter according to the ninth aspect, wherein the wavelength of the pump light is a wavelength band before the wavelength conversion or a wavelength band. When entering the wavelength band after the conversion, the wavelength of the wavelength-division multiplexed signal light not subject to the wavelength conversion in the wavelength band is shifted from the wavelength of the pump light so that both wavelengths do not overlap. .

According to a tenth aspect of the present invention, there is provided a wavelength converter for wavelength multiplexing optical transmission according to the eighth aspect, wherein the wavelength of the pump light is a wavelength band before wavelength conversion or a wavelength band. When the wavelength falls within the converted wavelength band, the wavelength of the pump light is shifted from the wavelength of the wavelength-division multiplexed signal light not subject to wavelength conversion within the wavelength band, so that both wavelengths do not overlap. .

The wavelength converter for wavelength multiplexing optical transmission according to claim 11 of the present invention is the wavelength converter for wavelength multiplexing optical transmission according to any one of claims 8 to 10, wherein the wavelength converter for wavelength multiplexing optical transmission has a wavelength of 1530 nm.
The wavelength conversion is performed between a wavelength multiplexed signal light having a wavelength of 1565 nm to 1565 nm and a wavelength multiplexed signal light having a wavelength of 1569 nm to 1610 nm.

According to a twelfth aspect of the present invention, there is provided a wavelength multiplexing optical transmission wavelength converter, wherein the wavelength multiplexing optical transmission wavelength converter according to any one of the eighth to tenth aspects has a wavelength of 1530 nm.
The wavelength conversion is performed between a wavelength multiplexed signal light having a wavelength of 1538 nm and a wavelength multiplexed signal light having a wavelength of 1540 nm to 1570 nm.

According to a thirteenth aspect of the present invention, there is provided a wavelength multiplexing optical transmission wavelength converter according to any one of the eighth to tenth aspects, wherein the wavelength multiplexing optical transmission wavelength converter according to any one of the eighth to tenth aspects has a wavelength of 1540 nm.
The wavelength conversion is performed between a wavelength multiplexed signal light having a wavelength of 1570 nm and a wavelength multiplexed signal light having a wavelength of 1570 nm to 1610 nm.

According to a fourteenth aspect of the present invention, there is provided a wavelength multiplexing optical transmission wavelength converter according to any one of the eighth to tenth aspects, wherein the wavelength multiplexing optical transmission wavelength converter according to any one of the eighth to tenth aspects has a wavelength of 1530 nm.
The wavelength conversion is performed between a wavelength multiplexed signal light having a wavelength of 1538 nm and a wavelength multiplexed signal light having a wavelength of 1570 nm to 1610 nm.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment of Wavelength Converter for Wavelength Multiplexed Optical Transmission) FIG. 1 shows an embodiment of a wavelength converter for wavelength multiplexed optical transmission according to the present invention. This wavelength converter 8
Is an optical fiber 5 to which a wavelength multiplexed signal light for wavelength conversion is inputted, and a pump light source 1 for generating pump light.
An optical multiplexer 2 for multiplexing the pump light with the optical fiber 5, a highly nonlinear optical fiber 3 which propagates the wavelength multiplexed signal light and the pump light to cause four-wave mixing, And an optical fiber 6 for outputting a wavelength-converted wavelength-division multiplexed signal light obtained through the optical filter 4. A polarization adjuster 7 is provided between the pump light source 1 and the optical multiplexer 2 in order to cause efficient four-wave mixing in the highly nonlinear optical fiber 3.

The emission wavelength of the pump light source 1 and the transmission wavelength of the optical filter 4 are set to appropriate wavelengths. The emission wavelength of the pump light source 1 can be determined from the wavelength band of the wavelength multiplexed signal light input to the optical fiber 5 and the wavelength band of the wavelength multiplexed signal light output from the optical fiber 6. Wavelength multiplexed signal light having a wavelength from ₁₁ to λ ₁₂ (λ ₁₂ > λ ₁₁ ) is converted from a wavelength λ ₂₁ (λ ₂₁ > λ ₁₂ ) to a wavelength λ ₂₂ (λ ₂₂ >
λ ₂₁ ) (or to perform the inverse conversion thereof), the wavelength λ _{P of the} pump light is determined based on the phase matching condition of four-wave mixing by the wavelength determined by the above equation (1). Set to. In addition, the optical filter 4 changes the wavelength λ ₂₁ to the wavelength λ ₂₂
Is set to be able to transmit light.

Table 2 shows some examples of wavelength conversion and the pump light wavelength λ _P required for the example.

[0029]

[Table 2]

The wavelength λ _P of the pump light generated by the pump light source 1 is determined by the wavelengths before and after the wavelength conversion.
It is preferable to adopt a structure that allows some wavelength adjustment by each wavelength conversion.

(First Embodiment of WDM Optical Transmission System)
In the EDFA with gain flattening, a wavelength band called C-band 15
A wavelength division multiplexing optical transmission system having a wavelength band between 30 nm and 1565 nm (35 nm) and a wavelength band called L-band between 1569 nm and 1610 nm (41 nm) is described in Table 1 as an example.
In the case of TT, 20ch signal light can be transmitted to C-band, and L-band
30ch of signal light can be transmitted to a single optical fiber, and a total of 50ch of signal light can be transmitted to one optical fiber. In this embodiment, two independent systems are prepared: a C-band only system (hereinafter referred to as system C) and an L-band only system (hereinafter referred to as system L). One wavelength multiplexing optical transmission system is constructed by connecting with the wavelength converter 8 having the configuration shown in FIG.

In the system C and the system L, the system C
, The wavelength of the entire band of the system C is collectively converted into an arbitrary band of the system L. For simplicity,
The system C performs two-wave WDM, and the system L performs three-wave WDM. These two systems C, L
When the two waves in the system C are transferred to the system L (or vice versa), the wavelength of the pump light λ _P of the wavelength converter is determined by which wavelength of the system L is converted, as shown in FIG. In the example, it is determined as in the following equation (4). λ _P = 2λ _1L λ _2C / (λ _1L + λ _2C ) (4)

As shown in FIG. 2, when the wavelength λ _{P of the} pump light falls within the band of the system L to which the wavelength is to be converted, the signal light of the wavelength λ _{3L which} is not subject to the wavelength conversion in the system L overlaps with the pump light. Therefore, it is necessary to shift the wavelength λ _{P of the} pump light from the wavelength λ _{3L of the} signal light. In particular,
The signal light in the system C has a wavelength λ _1C = 1540 nm and a wavelength λ _2C
= 1550 nm, and when the wavelength λ _2C is converted to the wavelength λ _1L = 1600 nm, the wavelength λ _P of the pump light needs to be 1575 nm.
In this case, the signal light having the wavelength λ _1C is converted into the wavelength λ _2L = 1610 nm. The wavelength λ _{P of the} pump light is in the band of the system L, and may overlap with the signal light in the band that is not subject to wavelength conversion. If they overlap, the wavelength λ _{P of the} pump light is shifted to a wavelength that does not overlap any of the wavelengths outside the wavelength conversion target in the system L. As a result, the wavelength after the wavelength conversion changes, but even if the wavelength changes, transmission is possible within the band of the system L. In this way, it is possible to avoid the overlap between the wavelength of the signal light and the wavelength of the pump light.

(Embodiment 2 of WDM optical transmission system)
As shown in FIG. 3, a system 10 for wavelength-division multiplexing transmission using a wavelength band of 1530 nm to 1550 nm in the C-band, and a wavelength using a wavelength band of 1570 nm to 1159.07 nm in the L-band independent of this. A system 11 for multiplex transmission is prepared. In the system 10, the terminal stations 14 and 15 are connected by an optical fiber cable 12 to which an EDFA 18 is attached, and the optical fiber cable 12 and the EDFA 18 are optimized for signal transmission of wavelength multiplexed signal light shown in FIG. Similarly, in the system 11, the terminal stations 16 and 17 are connected by an optical fiber cable 13 having an EDFA 19 attached thereto.
The EDFA 19 is optimized for signal transmission of the wavelength multiplexed signal light shown in FIG. In the present embodiment, these two systems 10 and 11 are connected by the wavelength converter 8 having the configuration shown in FIG. 1 to construct one system. If the terminal stations 15 and 17 of the systems 10 and 11 are connected by an optical fiber cable without using the wavelength converter 8, the signal from the terminal station 15 received by the terminal station 17 (A in FIG. The signal is transmitted to the station 16, but the signal from the terminal 15 (A in FIG. 3) between the terminal stations 16 and 17 is optimized for the wavelength multiplexed signal light shown in FIG. Cannot be transmitted to the terminal station 16 in an appropriate state.

In the present embodiment, the terminal stations 15 and 17 are connected by a wavelength converter 8 having a pump light wavelength λ _P 1559.94 nm, and the C-band signal of the terminal station 15 is transmitted as shown in FIG. L-
Since the band is converted to a band signal and transmitted to the system 11, the signal transmission between the two systems 10 and 11 can be performed without deterioration. In addition, each system 1
If there is room in the transmission band at 0 and 11 and signal light that is not subject to wavelength conversion can be transmitted, signal light can be transmitted at a wavelength that does not match the wavelength λ _{P of the} pump light.

(Third Embodiment of WDM Optical Transmission System)
A wavelength division multiplexing optical transmission system A in the 1530 nm band, a wavelength division multiplexing optical transmission system B in the 1560 nm band, and a wavelength division multiplexing optical transmission system C in the 1610 nm band are prepared. These three systems A, B,
C are connected by the wavelength converter 8 of FIG. 1 to construct one system. Here, as shown in FIG. 4, system A has two waves.
The WDM and the systems B and C will be briefly described as performing WDM of three waves.

In these systems A, B and C, system A
Since the bandwidth of the system A is the narrowest, in order to perform wavelength conversion between the systems A, B, and C to share information, the bandwidth may be limited to the bandwidth of the system A. For example, two signal light waves are shared by the pump light having the wavelength λ _{P1 / 2} between the systems A and B, and two signal light waves are shared by the pump light having the wavelength λ _{P1 / 3} between the systems A and C. , C can be shared by the pump light having the wavelength λ _{P2 / 3} . Further, in this case, since the systems B and C having a wide band include a band which is not subject to wavelength conversion, one band of signal light can be shared by wavelength conversion by pump light of another wavelength λ _P2-3 in this band. .

[0038]

According to the wavelength multiplexing optical transmission system and the wavelength converter for wavelength multiplexing optical transmission of the present invention, even in a wavelength multiplexing optical transmission system in which a large number of signal lights are arranged in a limited band, the wavelength conversion is possible. The pump light and the signal light can be prevented from overlapping, and the band can be used efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a wavelength converter for wavelength division multiplexing optical transmission of the present invention.

FIG. 2 is a first embodiment of the wavelength division multiplexing optical transmission system of the present invention, and is an explanatory diagram showing signal light in the system.

FIG. 3 is a second embodiment of the wavelength division multiplexing optical transmission system of the present invention, and is an explanatory diagram showing an outline of the system and signal light in the system.

FIG. 4 is a third embodiment of the wavelength division multiplexing optical transmission system of the present invention, and is an explanatory diagram showing signal light in the system.

FIG. 5 is an explanatory diagram showing the wavelength dependence of an EDFA.

FIG. 6 is an explanatory diagram showing an example of wavelength conversion by four-wave mixing.

FIG. 7 is an explanatory diagram showing an example of a communication system in which independent systems are connected by a wavelength converter.

FIG. 8 is an explanatory diagram showing another example of a communication system in which an independent system is connected by a wavelength converter.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pump light source 2 optical multiplexer 3 optical fiber having high nonlinearity 4 optical filter 5 optical fiber 6 optical fiber 7 polarization controller

Claims (14)

[Claims] 1. A wavelength-division multiplexed signal light having wavelengths λ ₁₁ to λ ₁₂ (λ ₁₂ > λ ₁₁ ) belonging to one of two or more different wavelength bands,
Wavelength λ ₂₁ belonging to a different wavelength band (λ ₂₁ > λ ₁₂ )
From the wavelength λ ₂₂ (λ ₂₂ > λ ₂₁ ) to the wavelength λ _P (λ _P
= 2λ ₁₂ λ ₂₁ / (λ ₁₂ + λ ₂₁ )) In a wavelength multiplexing optical transmission system in which wavelength conversion is performed by pump light to enable wavelength multiplex communication between different wavelength bands, the wavelength of the pump light before wavelength conversion is changed. When entering the wavelength band or the wavelength band after the wavelength conversion, the wavelength of the wavelength-division multiplexed signal light not subject to the wavelength conversion in the wavelength band and the wavelength of the pump light are shifted so as not to overlap. WDM optical transmission system. 2. The wavelength multiplexing optical transmission system according to claim 1, wherein when the wavelength of the pump light falls within the wavelength band before the wavelength conversion or within the wavelength band after the wavelength conversion, the wavelength conversion target within the wavelength band is excluded. A wavelength multiplexing optical transmission system wherein the wavelength of the wavelength multiplexing signal light is shifted from the wavelength of the pump light so that the two wavelengths do not overlap. 3. The wavelength multiplexing optical transmission system according to claim 1, wherein when the wavelength of the pump light falls within the wavelength band before the wavelength conversion or within the wavelength band after the wavelength conversion, the wavelength of the pump light is set within the wavelength band. A wavelength multiplexing optical transmission system characterized in that the wavelength multiplexing optical transmission system is arranged so as to be shifted from the wavelength of the wavelength multiplexing signal light not subject to the wavelength conversion so that the two wavelengths do not overlap. 4. The wavelength multiplexing optical transmission system according to claim 1, wherein a bandwidth used for wavelength conversion of each wavelength band is set based on a bandwidth of a wavelength band having the narrowest band. A wavelength multiplexing optical transmission system characterized by using a band other than a band used for wavelength conversion in other wavelength bands for communication with another wavelength multiplexing transmission system. 5. The wavelength multiplexing optical transmission system according to claim 1, wherein a bandwidth used for wavelength conversion of each wavelength band is based on a bandwidth of a wavelength band having the narrowest band. A wavelength division multiplexing optical transmission system characterized in that only wavelength bands used for wavelength conversion are used in each wavelength band. 6. The wavelength multiplexing optical transmission system according to claim 1, wherein two different wavelength bands are a C-band having a wavelength band of 1530 nm to 1565 nm, and a wavelength band of 1569 nm to 1610 nm. A wavelength multiplexing optical transmission system wherein wavelength conversion is performed between these wavelength bands. 7. A wavelength division multiplexing optical transmission system according to claim 1, wherein wavelength conversion is performed between two or more independent wavelength division multiplexing optical transmission systems. A wavelength division multiplexing optical transmission system characterized by comprising one wavelength division multiplexing optical transmission system. 8. A wavelength-division multiplexed signal light having wavelengths λ ₁₁ to λ ₁₂ (λ ₁₂ > λ ₁₁ ) belonging to one of two or more different wavelength bands;
Wavelength λ ₂₁ belonging to a different wavelength band (λ ₂₁ > λ ₁₂ )
From the wavelength λ ₂₂ (λ ₂₂ > λ ₂₁ ) to the wavelength λ _P (λ _P
= 2λ ₁₂ λ ₂₁ / (λ ₁₂ + λ ₂₁ )) The wavelength of the pump light is used in a wavelength multiplexing light transmission wavelength converter for performing wavelength multiplexing communication between different wavelength bands by performing wavelength conversion with the pump light. When the wavelength falls within the wavelength band before the wavelength conversion or within the wavelength band after the wavelength conversion, the wavelength of the wavelength-division multiplexed signal light not subject to the wavelength conversion in the wavelength band is set to be shifted from the wavelength of the pump light so as not to overlap. A wavelength converter for wavelength-division multiplexed light transmission. 9. The wavelength converter according to claim 8, wherein the wavelength of the pump light falls within the wavelength band before the wavelength conversion or within the wavelength band after the wavelength conversion. A wavelength converter for wavelength-division multiplexed light transmission, wherein wavelengths of wavelength-division multiplexed signal light not to be converted are shifted from wavelengths of pump light so that both wavelengths do not overlap. 10. The wavelength converter according to claim 8, wherein when the wavelength of the pump light falls within the wavelength band before the wavelength conversion or within the wavelength band after the wavelength conversion, the wavelength of the pump light is set to the wavelength. A wavelength converter for wavelength-division multiplexed light transmission, wherein the wavelength converter is set so as to be shifted from a wavelength of a wavelength-division multiplexed signal light not subject to wavelength conversion within a wavelength band so that both wavelengths do not overlap. 11. The wavelength converter for wavelength-division multiplexed optical transmission according to any one of claims 8 to 10, comprising: a wavelength-division multiplexed signal light having a wavelength of 1530 nm to 1565 nm;
A wavelength converter for wavelength-division multiplexed light transmission, which performs wavelength conversion between the wavelength-division multiplexed signal light and the wavelength-division multiplexed signal light. 12. A wavelength converter for wavelength-division multiplexed optical transmission according to claim 8, wherein said wavelength converter is a wavelength-division multiplexed signal light having a wavelength of 1530 nm to 1538 nm and a wavelength of 1540 nm to 1570 nm.
A wavelength converter for wavelength-division multiplexed light transmission, which performs wavelength conversion between the wavelength-division multiplexed signal light and the wavelength-division multiplexed signal light. 13. A wavelength multiplexing optical transmission wavelength converter according to any one of claims 8 to 10, comprising: a wavelength multiplexing signal light having a wavelength of 1540 nm to 1570 nm;
A wavelength converter for wavelength-division multiplexed light transmission, which performs wavelength conversion between the wavelength-division multiplexed signal light and the wavelength-division multiplexed signal light. 14. A wavelength multiplexing optical transmission wavelength converter according to any one of claims 8 to 10, comprising: a wavelength multiplexing signal light having a wavelength of 1530 nm to 1538 nm;
A wavelength converter for wavelength-division multiplexed light transmission, which performs wavelength conversion between the wavelength-division multiplexed signal light and the wavelength-division multiplexed signal light.