JP2003188830A - Wavelength multiplex light transmission apparatus, relaying apparatus, distribution apparatus, and wavelength multiplex light transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength multiplex light transmission system that can amplify a wavelength multiplex signal light with a plurality of wavelength bands by using an optical amplifier for a prescribed kind of single wavelength band and relay or distribute the amplified signal light as required. <P>SOLUTION: An optical demultiplexer 3 demultiplexes a wavelength multiplex signal light with S, C, L bands into each of the S, C, L bands. Pre-stage wavelength converters 7, 8 respectively apply wavelength conversion to the signal light by each of S, L bands obtained from the optical demultiplexer 3 into the signal light with the C band. Optical amplifiers 11 to 13 respectively amplify the three signal lights with the C band obtained from the optical demultiplexer 3 or the pre-stage wavelength conversions 7, 8 by each signal light respectively corresponding to the signal lights with each of the S, C, L bands obtained from the optical demultiplexer 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing system wavelength division multiplexing optical transmission system, and more particularly to a wavelength division multiplexing optical transmission system for transmitting wavelength division multiplexing signal light having a plurality of wavelength bands. The present invention also relates to a wavelength multiplexing optical transmission device, a relay device, and a distribution device used in such a wavelength multiplexing optical transmission system.

[0002]

2. Description of the Related Art With the increase in data traffic in recent years, in an optical communication system (optical transmission system), the modulation speed is increased and the wavelengths of signals of a plurality of channels are multiplexed and transmitted as optical signals of different wavelengths. The division multiplex (WDM) system has been put into practical use.

In the current optical transmission system based on the wavelength division multiplexing system, the attenuation caused by transmission is amplified as it is by using an optical fiber amplifier, or the optical signal is collectively amplified without separating a plurality of channels. The optical fiber amplifier used here is composed of a silica single mode optical fiber doped with a rare earth element.

In particular, as a rare earth element, erbium (E
r) -doped erbium-doped optical fiber (ED
F) Amplifier (EDFA) is 1530 nm to 1570 n
Since it can efficiently amplify a wavelength band of about 40 nm over m, it is most widely used.

The optical fiber amplifier is usually a WD on the transmission side.
It is divided into three types: booster amplifier installed in M terminal station, in-line amplifier installed at a predetermined interval in the middle of transmission line, and preamplifier installed in WDM terminal station on the receiving side. Will be placed. For example, in a long-distance submarine cable with a transmission distance of 6,000 km or more, the number of in-line amplifiers is 10
It will exceed 0.

The optical fiber amplifier is an optical isolator that prevents reflection of light to the transmission line, a WDM coupler that combines pump light into an EDF, a gain equalizer that suppresses a difference in gain between channels within a predetermined range, and an overall unit. It is configured by a variable attenuator or the like that stabilizes the signal level of. Especially E
In DFA, it is common to use two wavelengths of 0.98 μm and 1.48 μm as pump light sources in order to obtain high conversion efficiency.

An EDFA that obtains even higher efficiency by using orthogonal polarization for each pump wavelength.
Also exists. In that case, four sets of pump light sources and WDM couplers are required for one EDFA.

The wavelength band in which the EDFA is used is a wavelength band extending from 1530 nm to 1570 nm as described above, and is a wavelength band called C band. In addition to this, the silica-based optical fiber used for optical transmission has a wavelength band of 1480 nm to 1510 n, which has a practical transmission loss.
There is an S band of m and a region called the L band extending from 1570 nm to 1610 nm.

Of these, the EDFA has a gain only in the C band as described above. As a fiber amplifier for the S band, a thulium-doped fiber amplifier has been studied, but it is necessary to use fluoride as a host material.
The cost is higher than that of EDF using quartz as a host material, and it has not yet been put to practical use. For L band,
The gain shift can be realized by increasing the total length of the EDF, but the gain is lower than that in the amplification in the C band.

On the other hand, in response to the demand for increasing the transmission capacity, it is conceivable to use a wide wavelength band to transmit a large number of channels by one optical fiber. That is,
It is conceivable to transmit wavelength-multiplexed signal light having a plurality of wavelength bands through one optical fiber. For that purpose, multi-band transmission using not only the C band but also the S and L bands is considered, and an experiment has been conducted.

In these experiments, since there is no optical fiber amplifier having a sufficient gain over the entire C, S, and L wavelength bands, the wavelengths are separated for each band before amplification by the optical fiber amplifier. Then, by using different optical fiber amplifiers corresponding to each band, amplification is performed for each band, and then multiple wavelengths are multiplexed by a multiplexer to realize multiple band transmission. ing.

[0012]

However, as compared with the EDFA for the C band, the L-band and S-band optical fiber amplifiers have a low degree of perfection and are inferior in gain, so that multi-band transmission is realized. When doing so, it becomes an obstacle due to poor reliability and cost. Also,
Since optical fiber amplifiers operating in different wavelength bands are manufactured, there are problems that mass production cannot be expected, cost is further increased, and maintenance is difficult.

The present invention has been made in view of the above circumstances, and it is possible to amplify a wavelength-multiplexed signal light having a plurality of wavelength bands by using an optical amplifier for a predetermined wavelength of a single wavelength band. Moreover, the amplified signal light can be relayed, distributed, or switched as necessary.
An object is to provide an apparatus for wavelength division multiplexing optical transmission.

Another object of the present invention is to provide a repeater, a distributor and a wavelength division multiplexing optical transmission system using such a wavelength division multiplexing optical transmission apparatus.

[0015]

In order to solve the above problems, a wavelength division multiplexing optical transmission apparatus according to a first aspect of the present invention divides a wavelength division multiplexing signal light having a plurality of wavelength bands into each wavelength band. Wavelength demultiplexing unit, and the signal light of a wavelength band other than one predetermined wavelength band of the signal light of each wavelength band obtained from the demultiplexing unit is wavelength-divided into the signal light of the predetermined wavelength band, respectively. A pre-wavelength conversion unit for converting, and a plurality of signal light of the predetermined wavelength band obtained from the demultiplexing unit or the pre-wavelength conversion unit, an optical amplification unit for amplifying each signal light, respectively. It is a thing. The plurality of signal lights may correspond to the signal lights of the respective wavelength bands obtained from the demultiplexing unit.

A wavelength division multiplex optical transmission apparatus according to a second aspect of the present invention is the apparatus according to the first aspect, wherein the optical amplification section is
It includes one or more optical fiber amplifiers or waveguide type optical amplifiers for the predetermined wavelength band.

A wavelength division multiplexing optical transmission apparatus according to a third aspect of the present invention is the apparatus according to the first or second aspect, wherein the pre-wavelength conversion section includes one or more quasi phase matching elements.

A wavelength division multiplexing optical transmission apparatus according to a fourth aspect of the present invention is the apparatus according to any one of the first to third aspects, wherein at least one of the plurality of signal lights amplified by the optical amplifying section is a signal. It is provided with a post-wavelength conversion unit that converts the wavelength of light into signal light of a wavelength band different from the predetermined wavelength band.

A wavelength division multiplexing optical transmission apparatus according to a fifth aspect of the present invention is the apparatus according to the fourth aspect, wherein the post-wavelength conversion section includes one or more quasi phase matching elements.

A wavelength division multiplexing optical transmission apparatus according to a sixth aspect of the present invention is the apparatus according to the fourth or fifth aspect, wherein the post-wavelength conversion section has the plurality of signals respectively amplified by the optical amplification section. Of the lights, the signal lights other than the selected one signal light are wavelength-converted into the signal lights of different wavelength bands other than the predetermined wavelength band.

A wavelength division multiplex optical transmission apparatus according to a seventh aspect of the present invention is the apparatus according to the fourth or fifth aspect, wherein the post-wavelength conversion section has the plurality of signals respectively amplified by the optical amplification section. Of the light, the wavelength band when the wavelength band when obtained from the demultiplexing unit is a wavelength band other than the predetermined wavelength band, the wavelength band before wavelength conversion by the pre-wavelength conversion unit for the signal light The wavelength is converted into signal light.

The wavelength division multiplexing optical transmission apparatus according to an eighth aspect of the present invention is the apparatus for wavelength multiplexing optical transmission according to any one of the fourth to seventh aspects, wherein the plurality of signal lights respectively amplified by the optical amplifying section and the post-processing unit are installed. Among the signal lights obtained from the wavelength conversion unit, there is provided a multiplexing unit that multiplexes at least two signal lights in different wavelength bands.

An apparatus for wavelength division multiplexing optical transmission according to a ninth aspect of the present invention is the device according to the sixth aspect.
It is provided with a multiplexer for multiplexing one signal light and all the signal lights obtained from the post-wavelength converter.

A wavelength division multiplexing optical transmission apparatus according to a tenth aspect of the present invention is the wavelength division multiplexing optical transmission apparatus according to the seventh aspect, wherein the plurality of signal lights respectively amplified by the optical amplifying section are obtained from the demultiplexing section. The signal light having the wavelength band at the time of the predetermined wavelength band and the signal light obtained from the post-wavelength conversion unit are combined.

A relay device according to an eleventh aspect of the present invention is
A repeater arranged in the middle of a transmission line for transmitting wavelength-multiplexed signal light having a plurality of wavelength bands, including the wavelength-multiplexed optical transmission apparatus according to any one of the eighth to tenth aspects.

A dispenser according to the twelfth aspect of the invention is
A distribution device that distributes wavelength-multiplexed signal light having a plurality of wavelength bands into two or more, including the wavelength-multiplexed optical transmission device according to any one of the first to eighth aspects.

A wavelength division multiplexing optical transmission system according to a thirteenth aspect of the present invention is a wavelength division multiplexing optical transmission apparatus according to any one of the first to tenth aspects, a repeater according to the eleventh aspect, and the tenth aspect. And at least one of the dispensing devices according to the twelfth aspect.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION A wavelength division multiplexing optical transmission apparatus, a repeater, a distribution apparatus and a wavelength division multiplexing optical transmission system according to the present invention will be described below with reference to the drawings.

[First Embodiment]

FIG. 1 is a schematic block diagram showing the configuration of a wavelength division multiplexing optical transmission apparatus 1 according to the first embodiment of the present invention. FIG. 2 is a schematic configuration diagram schematically showing an example of the demultiplexer 3 in FIG.

The wavelength-division-multiplexed optical transmission apparatus 1 according to the present embodiment allows wavelength-division-multiplexed signal light having three wavelength bands of S, C, and L bands to be transmitted from one optical fiber 2 on the incident side as a transmission line. The wavelength-division-multiplexed signal light that has been incident is amplified, and the amplified wavelength-division-multiplexed signal light is output to the optical fiber 22 on the emission side as a transmission line.

The wavelength-division-multiplexed signal light is a signal light of a plurality of wavelengths included in the S band (the entire signal light is referred to as an S band signal light), and a signal of a plurality of wavelengths included in the C band. Light (the entire signal light is referred to as the C-band signal light) and signal light having a plurality of wavelengths included in the L band (the whole of the signal light is referred to as the L-band signal light). It is multiplexed.

As shown in FIG. 1, the wavelength division multiplexing optical transmission device 1 according to the present embodiment has a demultiplexer 3 and wavelength-converts the incident S-band signal light into C-band signal light and outputs the signal light. A pre-wavelength converter 7, a pre-wavelength converter 8 for wavelength-converting the incident L-band signal light into a C-band signal light and emitting the signal light, optical amplifiers 11 to 13, and an incident C-band. Post-wavelength converter 17 for wavelength-converting the signal light of S to the signal light of the S band and emitting the signal light, and a post-wavelength converter for wavelength-converting the signal light of the incident C band to the signal light of the L band and emitting the same. 18, the multiplexer 21, and the optical fibers 4-6, 9, 10, 14-16, 19, 20, which connect them.
And are equipped with.

Optical fibers 2, 4-6, 9, 10, 14-
Normally, silica-based single mode optical fibers are used as 16, 19, 20, and 22, but the invention is not limited to this.

The demultiplexer 3 receives the wavelength-multiplexed signal light having the S, C, and L bands, which is incident via the optical fiber 2, for each S,
The signals are demultiplexed for each of the C and L bands, and the demultiplexed signal lights of the S, C, and L bands are supplied to the incident ends of the optical fibers 4, 5, and 6, respectively.

The demultiplexer 3 is, for example, as shown in FIG.
Collimator lens 31 and condensing lenses 33, 35, 36
And thin film optical filters 32 and 34. The optical filter 32 has a characteristic of reflecting the light of the S band and transmitting the light of the C and L bands. The optical filter 34 has a property of transmitting light of the C band and reflecting light of the L band.

In the example shown in FIG. 2, the incident side optical fiber 1
The wavelength-multiplexed signal light transmitted and transmitted is collimated by the collimator lens 31, and then is transmitted by the optical filter 32 to the S-band signal light reflected by the optical filter 32 and C and C transmitted through the optical filter 32. L-band signal light is split. The S-band signal light reflected by the optical filter 32 is coupled to the optical fiber 4 by the condenser lens 33. The C- and L-band signal light transmitted through the optical filter 32 is converted into the C-band signal light transmitted through the optical filter 34 by the optical filter 34.
With the L-band signal light reflected by the optical filter 34,
Will be divided. The C-band signal light transmitted through the optical filter 34 is coupled to the optical fiber 5 by the condenser lens 35. The L-band signal light reflected by the optical filter 34 is coupled to the optical fiber 6 by the condenser lens 36.

The configuration of the demultiplexer 3 is not limited to the example shown in FIG. 2, and for example, an element such as an arrayed waveguide grating (AWG) or a fiber grating coupler that divides the optical path according to wavelength is used. A configuration can be adopted.

As the pre-wavelength converters 7 and 8 and the post-wavelength converters 17 and 18 described above, for example, a structure for realizing inter-band wavelength conversion by generating a difference frequency using a quasi phase matching element is adopted. You can

The quasi-phase matching element is an element that realizes phase matching between wavelengths caused by a fundamental wave and a second-order nonlinear action by compensating with a periodic structure. Many examples have been reported in which quasi-phase matching is realized by forming a periodic domain-inverted structure by applying a periodic electric field using ferroelectric material lithium niobate as a material.

One of the characteristics of the difference frequency generation in the quasi-phase matching is that it has a wide operating band, and by appropriately selecting the pump light, wavelength conversion between bands centering on the pump light is possible. In the 1.55 μm band, 1562 nm is used as pump light and 4 from 1552 nm to 1558 nm is used.
An example of collectively converting channels from 1565 nm to 1573 nm has been reported (MHChou, I.Brener, MMFe
jer, EEChanban, and SBChristman: IEEE Photonic
s Tecnol. Lett. No. 11,653 (1999)).

Also in this embodiment, for example, a quasi phase matching element having a periodic structure formed by applying an electric field to lithium niobate can be used. In this case, the pump light is 1 in the front wavelength converter 7 and the rear wavelength converter 17.
520 nm is used, and 1570 nm can be used for the front wavelength converter 8 and the rear wavelength converter 18. In addition,
The material of the quasi phase matching element is not limited to lithium niobate, and any material may be used as long as the same difference frequency can be generated.

As described above, the elements capable of performing collective wavelength conversion by the quasi phase matching element can be used for the pre-wavelength converters 7 and 8 and the post-wavelength converters 17 and 18, but the wavelength converters 7, 8 and The configurations of 17 and 18 are not limited to such a configuration. For example, in each band S, L, a signal is sent to each channel (each wavelength) by using a demultiplexing device such as AWG.
It is also possible to adopt a configuration in which the wavelength conversion is realized by dividing the light emitting element of each channel into an electric signal and converting the light emitting element having a desired wavelength with the electric signal after the division.

Referring again to FIG. 1, the S-band signal light demultiplexed by the demultiplexer 3 enters the pre-wavelength converter 7 through the optical fiber 4, and the pre-wavelength converter 7
The wavelength is converted into the signal light of C band. That is, the signal light of each wavelength in the S band, which is one output of the demultiplexer 3, is wavelength-converted into the signal light of each wavelength in the C band.

The L-band signal light demultiplexed by the demultiplexer 3 is incident on the pre-wavelength converter 8 via the optical fiber 6, and the pre-wavelength converter 8 wavelength-converts it into the C-band signal light. To be converted. That is, L which is one of the outputs of the demultiplexer 3
The signal light of each wavelength in the band is wavelength-converted into the signal light of each wavelength in the C band.

The C-band signal light after the wavelength conversion by the pre-wavelength converter 7 enters the C-band optical amplifier 11 through the optical fiber 9 and is amplified by the optical amplifier 11. The C-band signal light after wavelength conversion by the pre-wavelength converter 8 enters the C-band optical amplifier 13 through the optical fiber 10 and is amplified by the optical amplifier 13. The C-band signal light demultiplexed by the demultiplexer 3 enters the C-band optical amplifier 12 through the optical fiber 5 without being wavelength-converted, and is amplified by the optical amplifier 12.

Since the optical amplifiers 11 to 13 are all for the C band, the optical amplifiers having the same structure can be used. For example, as the optical amplifiers 11 to 13, an optical fiber amplifier such as an EDFA or a waveguide type optical amplifier (for example, E
An optical amplifier configured as a waveguide device using the same material as DFA) or the like can be used.

The C-band signal light amplified by the optical amplifier 11 is incident on the post-wavelength converter 17 via the optical fiber 14, and the post-wavelength converter 17 converts the wavelength of the signal by the pre-wavelength converter 7. It is converted into signal light of the same S band as the previous band. That is, all the signal light of each wavelength in the C band which is the output of the optical amplifier 11 is wavelength-converted into the signal light of each wavelength in the S band.

The signal light of the C band after being amplified by the optical amplifier 13 is incident on the post-wavelength converter 18 through the optical fiber 16, and the post-wavelength converter 18 converts the wavelength of the signal by the pre-wavelength converter 8. The signal light of the same L band as the previous band is converted. That is, all the signal light of each wavelength in the C band which is the output of the optical amplifier 13 is wavelength-converted into the signal light of each wavelength in the L band.

S after wavelength conversion by the post-wavelength converter 17
The signal light of the band is transmitted through the optical fiber 19, the signal light of the L band after the wavelength conversion by the post-wavelength converter 18 is transmitted through the optical fiber 20, and the signal light of the C band after being amplified by the optical amplifier 12 is at the wavelength. It is incident on the multiplexer 21 via the optical fiber 15 without being converted. These S, C, and L band signal lights are combined by the combiner 21 to become wavelength-multiplexed signal light having the S, C, and L band wavelength bands again, and are incident on the optical fiber 22 on the emission side. It
As the multiplexer 21, for example, one having the same configuration as that of the demultiplexer 3 shown in FIG. 2 can be used. However, in this case, the input / output relationship is reversed.

In the present embodiment, the pre-wavelength converters 7 and 8 as a whole are S, C, and
Of the signal light of each L band, the signal light of the S and L bands, which is a wavelength band other than the C band which is one predetermined wavelength band of the S, C, and L bands, is converted into the signal light of the C band. A pre-wavelength conversion unit that performs wavelength conversion is configured.

In this embodiment, the optical amplifiers 11 to 11 are also used.
13 as a whole, each S, C, L obtained from the demultiplexer 3
The signal lights of the three C bands obtained from the demultiplexer 3 or the pre-wavelength conversion unit respectively corresponding to the signal lights of each band are
An optical amplification unit that amplifies each signal light is configured.

Further, in the present embodiment, the post-wavelength converters 17 and 18 as a whole have at least one of the three C-band signal lights respectively amplified by the optical amplifier (the present embodiment). 2) signal light S, which has a wavelength band different from the C band which is the predetermined wavelength band,
A post-wavelength conversion unit that converts the wavelength of each of the L-band signal lights is configured.

As can be seen from the above description, according to the present embodiment, there is no need to use the three types of optical amplifiers of S band optical amplifier, C band optical amplifier and L band optical amplifier as in the conventional case. , Same type C band optical amplifier 1
1 to 13 are used to amplify the wavelength-multiplexed signal light having the S, C, and L wavelength bands transmitted by the optical fiber 2 without finally changing the signal form.
The wavelength-multiplexed signal light having the L-band wavelength band can be obtained from the optical fiber 22.

Thus, according to the present embodiment, S,
Amplifies wavelength multiplexed signal light in C and L 3-band transmission using a C-band optical amplifier that is most widely used and has a high degree of perfection and excellent gain characteristics compared to L-band and S-band optical amplifiers. Therefore, it is possible to improve reliability and reduce cost. Further, since only the C-band optical amplifier is used as the optical amplifier, the mass production effect of the C-band optical amplifier can be expected, the cost can be further reduced, and the maintenance becomes easy.

Specific examples of applications of the wavelength division multiplexing optical transmission apparatus 1 according to this embodiment will be described with reference to fifth and sixth embodiments described later.

In this embodiment, the signal light of each S, C, L band in the input wavelength-multiplexed signal light and the signal light of each S, C, L band in the output wavelength-multiplexed signal light have the same band. The signal lights of the respective wavelengths have the same signal content. However, in the present invention, depending on the application, the signal correspondence between the input band and the output band may be fixedly changed, or the signal correspondence may be switched by an optical switch or the like. For example, in FIG. 1, the rear wavelength converter 17 and the rear wavelength converter 18 are switched in position (or the optical path is switched by an optical switch or the like so that the positions can be switched). Of the signal light of each wavelength in the S band of the wavelength-multiplexed signal light and the signal contents of the signal light of each wavelength in the L-band of the output wavelength-multiplexed signal light are the same, Each signal content indicated by the signal light of each wavelength in the L band in the wavelength multiplexed signal light and each signal content indicated by the signal light of each wavelength in the S band in the output wavelength multiplexed signal light can be made the same. . Further, for example, in FIG. 1, the post-wavelength converter 18 is arranged instead of the post-wavelength converter 17, and the post-wavelength converter 17 is arranged between the optical amplifier 12 and the multiplexer 21. By directly inputting the output of the amplifier 13 to the multiplexer 21, each signal content indicated by the signal light of each wavelength in the S band in the input wavelength multiplexed signal light and the L band in the output wavelength multiplexed signal light Each signal content indicated by the signal light of each wavelength is made the same, and each signal content indicated by the signal light of each wavelength in the C wavelength band of the input wavelength multiplexed signal light and each of the S band in the wavelength multiplexed signal light of the output Each signal content indicated by the signal light of the wavelength is made the same, and each signal content indicated by the signal light of each wavelength within the L band in the input wavelength multiplexed signal light and each wavelength within the C band in the output wavelength multiplexed signal light Signal light of each And No. contents can each be the same. The above points are related to the wavelength division multiplexing optical transmission apparatus 31 according to the second to fourth embodiments described later.
The same applies to 41 and 51.

[Second Embodiment]

FIG. 3 is a schematic block diagram showing the structure of a wavelength division multiplexing optical transmission apparatus 31 according to the second embodiment of the present invention. In FIG. 3, elements that are the same as or correspond to the elements in FIG. 1 are assigned the same reference numerals, and duplicate descriptions thereof will be omitted.

The wavelength-division-multiplexed optical transmission device 31 according to the present embodiment is different from the wavelength-division-multiplexed optical transmission device 1 shown in FIG. 1 in that in the present embodiment, the post-wavelength converter 17, shown in FIG.
18, the multiplexer 21, and the optical fibers 19, 20, and 22 are removed, and the optical fibers 14 to 16 are respectively used as optical fibers on the output side.

According to this embodiment, the signal light of each S, C, and L band in the input wavelength-multiplexed signal light is converted into C of the same type.
It can be amplified by using the band optical amplifiers 11 to 13 and separated from each other, and all can be taken out as signal light of C band.

Specific examples of uses of the wavelength division multiplexing optical transmission apparatus 31 according to the present embodiment will be described later in fifth and sixth embodiments.
Will be described in connection with the embodiment.

[Third Embodiment]

FIG. 4 is a schematic block diagram showing the structure of a wavelength division multiplexing optical transmission apparatus 41 according to the third embodiment of the present invention. In FIG. 4, elements that are the same as or correspond to the elements in FIG. 1 are assigned the same reference numerals, and duplicate descriptions thereof will be omitted.

The wavelength-division-multiplexing optical transmission device 41 according to the present embodiment is different from the wavelength-division-multiplexing optical transmission device 1 shown in FIG. 1 in that in the present embodiment, the multiplexer 21 is the post-wavelength converter 17. S-band signal light from C and C from the optical amplifier 12
Only the point that the signal light of the band is combined and the point that the post-wavelength converter 18 and the optical fiber 20 are removed and the optical fiber 16 is used as the optical fiber on the emitting side are only. .

According to the present embodiment, the signal light of each S, C, L band in the input wavelength-multiplexed signal light is converted into C of the same type.
Amplify using the band optical amplifiers 11 to 13, and
When the source is the S and C bands, the wavelength-division multiplexed signal lights of the S and C bands are separated into the wavelength-multiplexed signal light of the S and C bands. Can be extracted as C-band signal light.

A specific example of the use of the wavelength division multiplexing optical transmission apparatus 41 according to this embodiment will be described with reference to the sixth embodiment described later.

[Fourth Embodiment]

FIG. 5 is a schematic block diagram showing the structure of a wavelength division multiplexing optical transmission apparatus 51 according to the fourth embodiment of the present invention. In FIG. 5, elements that are the same as or correspond to the elements in FIG. 1 are assigned the same reference numerals, and duplicate descriptions thereof will be omitted.

The wavelength-division-multiplexing optical transmission device 51 according to this embodiment differs from the wavelength-division-multiplexing optical transmission device 1 shown in FIG. 1 in that the multiplexer 21 in FIG. The only difference is that the optical fibers 19, 15 and 20 are used as optical fibers on the output side.

According to this embodiment, the signal light of each S, C, L band in the input wavelength-multiplexed signal light is converted into C of the same type.
It can be amplified by using the band optical amplifiers 11 to 13 and separated from each other, and respectively extracted as signal light of the same band as the original band.

A specific example of the use of the wavelength division multiplexing optical transmission apparatus 51 according to this embodiment will be described with reference to a sixth embodiment described later.

[Fifth Embodiment]

FIG. 6 is a schematic block diagram showing the structure of a wavelength division multiplexing optical transmission system according to the fifth embodiment of the present invention.

The wavelength division multiplexing optical transmission system according to the present embodiment has a transmitter 61, repeaters 62 and 63, a receiver 64, and optical fibers 65 to 67 connecting them.
And is configured to perform S, C, L 3-band transmission.

The transmitter 61 emits a wavelength multiplexed signal light having three wavelength bands of S, C and L bands. This wavelength-division-multiplexed signal light propagates through the optical fiber 65 and repeater 62
Is incident on. The repeater 62 amplifies the wavelength multiplexed signal light that has entered. The wavelength-multiplexed signal light amplified by the repeater 62 propagates through the optical fiber 66 and enters the repeater 63. The repeater 63 amplifies the wavelength multiplexed signal light that has entered. The wavelength-multiplexed signal light amplified by the repeater 63 propagates through the optical fiber 67, enters the receiver 64, and is received by the receiver 64.

As described above, the wavelength-multiplexed signal light having three wavelength bands of S, C, and L bands emitted from the transmitter 61 is sequentially amplified by the repeaters 62 and 63, and is transmitted through the transmission line (the optical fiber 65). , 66, 67) and is received by the receiving device 64.

In this embodiment, the wavelength division multiplexing optical transmission apparatus 1 shown in FIG. 1 is used as the repeaters 62 and 63, respectively. Therefore, in the wavelength division multiplexing optical transmission system according to the present embodiment, the reliability can be improved and the cost can be reduced, and the maintenance is easy.

Further, in the present embodiment, the wavelength multiplexing optical transmission device 31 shown in FIG. 3 is used as the front stage part of the receiving device 64. Therefore, when realizing the function of the preamplifier in the receiving device 64, the reliability can be improved and the cost can be reduced, and the maintenance can be facilitated. In addition, as a front stage part in the receiving device 64,
Since the wavelength-multiplexed optical transmission device 31 shown in FIG. 3 is used, as can be seen from FIG. A wavelength division multiplexing (WDM) type receiver of a single wavelength band using only the C band can be used. From this point as well, the reliability can be further improved, the cost can be further reduced, and the maintenance is further facilitated.

[Sixth Embodiment]

FIG. 7 is a schematic configuration diagram schematically showing a wavelength division multiplexing optical transmission system according to a sixth embodiment of the present invention.

The wavelength division multiplexing optical transmission system according to the present embodiment has a transmitter 71, repeaters 72 and 74, a distributor 73, receivers 75 and 76, and optical fibers 77 to 81 connecting them. And is configured to perform S, C, L three-band transmission and S, C two-band transmission.

The transmitting device 71 emits wavelength multiplexed signal light having three wavelength bands of S, C and L bands. The wavelength multiplexed signal light propagates through the optical fiber 77 and the repeater 72
Is incident on. The repeater 72 amplifies the wavelength multiplexed signal light that has entered. The wavelength-multiplexed signal light amplified by the repeater 72 propagates through the optical fiber 78 and enters the distributor 73. The distributor 73 splits the wavelength-multiplexed signal light of the S, C, and L bands, which has been incident, into the wavelength-multiplexed signal light of the S, C band and the signal light of the L band, and splits one of the S and C bands. The wavelength-multiplexed signal light is delivered to the optical fiber 79 as it is, and the other separated L-band signal light is wavelength-converted into C-band signal light and delivered to the optical fiber 81. The C-band signal light distributed to the optical fiber 81 is
The light propagates through the optical fiber 81, enters the receiving device 76, and is received by the receiving device 76. The wavelength multiplexed signal light of the S and C bands distributed to the optical fiber 79 is
Is transmitted and is incident on the relay device 74. Repeater 74
Amplifies the incident wavelength-multiplexed signal light of the S and C bands. The wavelength-multiplexed signal light propagates through the optical fiber 80, enters the receiving device 75, and is received by the receiving device 75.

In this way, the wavelength-multiplexed signal light having the three wavelength bands of S, C, and L bands emitted from the transmission device 71 is amplified by the relay device 72 and split into two by the distribution device 73. . Then, the signal light that was distributed to one side and was the signal light of the L band on the side of the transmitting device 71 becomes the signal light of the C band, is received by the receiving device 76, and is distributed to the other wavelength multiplexing of the S and C bands. The signal light is amplified by the repeater 74 and then received by the receiver 75.

In the present embodiment, as the relay device 72,
A wavelength division multiplexing optical transmission device 1 shown in FIG. 1 is used.
Therefore, according to the present embodiment, the reliability can be improved and the cost can be reduced, and the maintenance can be facilitated.

Further, in this embodiment, the wavelength multiplexing optical transmission device 41 shown in FIG. 4 is used as the distribution device 73. Therefore, since the C-band optical amplifiers 11 to 13 having the same configuration can be used in the distribution device 73, reliability can be improved and cost can be reduced, and maintenance can be facilitated. Further, in the present embodiment, since the distribution device 73 is used, the signal content indicated by the L-band signal light in the wavelength-multiplexed signal light transmitted by the transmission device is supplied to the reception device 76 as the C-band signal light. To be done. Therefore, as the receiver 76, the conventional wavelength division multiplexing (WDM) of a single wavelength band using only the C band is used.
The receiver of the system can be used as it is, and also from this point, the reliability can be improved and the cost can be reduced.

Further, in the present embodiment, as the repeater 74, a wavelength division multiplexing optical transmission apparatus (not shown) obtained by modifying the wavelength division multiplexing optical transmission apparatus shown in FIG. 4 as follows is used. That is, in this modified wavelength division multiplexing optical transmission device, in FIG. 4, the pre-wavelength converter 8, the optical amplifier 13, and the optical fibers 6, 10 and 16 are removed, and the demultiplexer 3 is
A wavelength division multiplexed signal light having S and C bands is demultiplexed for each S and C band, and the demultiplexed S and C band signal lights are supplied to the incident ends of the optical fibers 4 and 5, respectively. It was done. Therefore, according to the present embodiment, also from the configuration of the relay device 74, there is an advantage that the reliability can be improved and the cost can be reduced and the maintenance is easy.

Further, in the present embodiment, the receiving device 75
As a pre-stage of the above, a wavelength division multiplexing optical transmission apparatus (not shown) obtained by modifying the wavelength division multiplexing optical transmission apparatus 31 shown in FIG. 3 as follows is used. That is, in this modified wavelength division multiplexing optical transmission apparatus, in FIG. 3, the pre-wavelength converter 8, the optical amplifier 13, and the optical fibers 6, 10 and 16 are removed, and the demultiplexer 3 has S and C bands. The wavelength-division-multiplexed signal light is demultiplexed for each of the S and C bands, and the demultiplexed S and C band signal lights are supplied to the incident ends of the optical fibers 4 and 5, respectively. Therefore, when realizing the function of the preamplifier in the receiving device 75, the reliability can be improved and the cost can be reduced, and the maintenance can be facilitated. Not only that, the wavelength division multiplexing optical transmission device 31 shown in FIG. 3 which is modified as described above is used as the front stage part of the receiving device 75. The received signal can be used for each band by a conventional wavelength division multiplexing (WDM) type receiving device of a single wavelength band using only the C band. From this point as well, the reliability can be further improved, the cost can be further reduced, and the maintenance is further facilitated.

By the way, as the relay device 72 in FIG.
If the wavelength-multiplexed optical transmission apparatus 1 shown in FIG. 1 in which the rear wavelength converter 17 and the rear wavelength converter 18 are interchanged is used, unlike the present embodiment, the transmitter 71 is used.
The signal content indicated by the S-band signal light in the wavelength-multiplexed signal light having three wavelength bands of S, C, and L bands emitted from is given to the receiving device 76 as the L-band signal light, and the wavelength-multiplexed signal is also provided. The signal content indicated by the signal light of the L band in the light can be supplied to the receiving device 75 as the signal light of the S band. In such a case, if the optical path is switched by an optical switch or the like so that the arrangement of the post-wavelength converters 17 and 18 can be switched to the arrangement shown in FIG. The destination of the signal content indicated by the S-band signal light and the original signal content indicated by the L-band signal light can be freely switched between the receiving device 75 and the receiving device 76.

Here, in FIG. 7, the receiving devices 75, 7
Consider a case where the WDM optical transmission apparatus 51 shown in FIG. In this case, the optical fiber 2 in FIG. 5 corresponds to the optical fiber 78 in FIG. At this time, one optical fiber 19, 15 and 20 in FIG.
Two receiving devices (not shown) shall be arranged. In this case, the receiving device ahead of the optical fiber 20 is configured for the L band, the receiving device ahead of the optical fiber 15 is configured for the C band, and the receiving device ahead of the optical fiber 19 is S.
If the wavelength division multiplex optical transmission apparatus 51 shown in FIG.
Very preferred.

Although the respective embodiments of the present invention and the modifications thereof have been described above, the present invention is not limited to these embodiments.

[0092]

As described above, according to the present invention,
A wavelength-multiplexed signal light having a plurality of wavelength bands can be amplified by using an optical amplifier for a predetermined type of single wavelength band,
Moreover, it is possible to provide a wavelength division multiplexing optical transmission device capable of repeating, distributing, and switching the amplified signal light as necessary.

Further, according to the present invention, it is possible to provide a repeater, a distributor and a wavelength division multiplexing optical transmission system using such a wavelength division multiplexing optical transmission apparatus.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a configuration of a wavelength division multiplexing optical transmission apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram schematically showing an example of the demultiplexer in FIG.

FIG. 3 is a schematic block diagram showing a configuration of a wavelength division multiplexing optical transmission apparatus according to a second embodiment of the present invention.

FIG. 4 is a schematic block diagram showing the configuration of a wavelength division multiplexing optical transmission apparatus according to a third embodiment of the present invention.

FIG. 5 is a schematic block diagram showing a configuration of a wavelength division multiplexing optical transmission device according to a fourth embodiment of the present invention.

FIG. 6 is a schematic block diagram showing the configuration of a wavelength division multiplexing optical transmission system according to a fifth embodiment of the present invention.

FIG. 7 is a schematic block diagram showing the configuration of a wavelength division multiplexing optical transmission system according to a sixth embodiment of the present invention.

[Explanation of symbols]

1, 31, 41, 51 Wavelength multiplex optical transmission device 2 Incident side optical fiber 3 demultiplexer 4, 5, 6, 9, 10, 14, 15, 15, 16, 19, 20
Optical fiber 7,8 Pre-wavelength converter 11,12,13 C-band optical amplifier 17,18 Post-wavelength converter 21 Multiplexer 22 Output side fiber 61,71 Transmitter 62,63,72,74 Relay Device 64, 75 Receiver 65, 66, 67, 77, 78, 79, 80, 81 Optical fiber 73 Distributor

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Claims (13)

[Claims] 1. A demultiplexing unit that demultiplexes wavelength-multiplexed signal light having a plurality of wavelength bands for each wavelength band, and one of signal lights for each wavelength band obtained from the demultiplexing unit. Signal light of a wavelength band other than one predetermined wavelength band, a pre-wavelength conversion unit for wavelength conversion into the signal light of the predetermined wavelength band, respectively, the predetermined wavelength obtained from the demultiplexing unit or the pre-wavelength conversion unit An apparatus for wavelength-multiplexed optical transmission, comprising: an optical amplifier that amplifies a plurality of signal lights in each band for each signal light. 2. The apparatus for wavelength-multiplexed optical transmission according to claim 1, wherein the optical amplification section includes one or more optical fiber amplifiers or waveguide type optical amplifiers for the predetermined wavelength band. 3. The wavelength division multiplexing optical transmission apparatus according to claim 1, wherein the front wavelength conversion unit includes one or more quasi phase matching elements. 4. At least one signal light of the plurality of signal lights respectively amplified by the optical amplifier,
4. The wavelength division multiplexing optical transmission apparatus according to claim 1, further comprising a post-wavelength conversion unit that performs wavelength conversion into signal light having a wavelength band different from the predetermined wavelength band. 5. The wavelength division multiplexing optical transmission apparatus according to claim 4, wherein the post-wavelength conversion unit includes one or more quasi phase matching elements. 6. The post-wavelength conversion unit outputs the signal light other than the selected one signal light among the plurality of signal lights amplified by the optical amplification unit to a signal light other than the predetermined wavelength band. The wavelength-multiplexed optical transmission device according to claim 4 or 5, wherein wavelength conversion is performed on signal lights of different wavelength bands. 7. The post-wavelength conversion unit has a wavelength band obtained from the demultiplexing unit among the plurality of signal lights amplified by the optical amplification unit other than the predetermined wavelength band. 6. The wavelength division multiplexing optical transmission apparatus according to claim 4, wherein the signal light in the wavelength band is wavelength-converted into the signal light in the wavelength band before the wavelength conversion by the pre-wavelength conversion unit for the signal light. . 8. At least two wavelength bands different from each other among the plurality of signal lights respectively amplified by the optical amplifier and the signal lights obtained from the post-wavelength converter.
8. The wavelength division multiplexing optical transmission apparatus according to claim 4, further comprising a multiplexing unit that multiplexes two signal lights. 9. The wavelength division multiplexer according to claim 6, further comprising: a multiplexing unit that multiplexes the selected one signal light and all the signal lights obtained from the post-wavelength conversion unit. Optical transmission equipment. 10. The signal light having a wavelength band obtained from the demultiplexing unit out of the plurality of signal lights amplified by the optical amplifying unit is the predetermined wavelength band, and the post-processing unit. 8. The wavelength division multiplexing optical transmission apparatus according to claim 7, further comprising a multiplexing unit that multiplexes the signal light obtained from the wavelength conversion unit. 11. A repeater arranged in the middle of a transmission path for transmitting wavelength-multiplexed signal light having a plurality of wavelength bands, the wavelength-multiplexed optical transmission apparatus according to claim 8. A relay device comprising: 12. A distribution device that distributes wavelength-multiplexed signal light having a plurality of wavelength bands into two or more, including the wavelength-multiplexed optical transmission device according to any one of claims 1 to 8. Distributor. 13. At least one of the wavelength division multiplexing optical transmission apparatus according to claim 1, the relay apparatus according to claim 11, and the distribution apparatus according to claim 12.
And a wavelength division multiplexing optical transmission system.