JP2010206701A - Optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission system, or the like, which allows reduction in price, using a simple constitution. <P>SOLUTION: Optical signals of the wavelength λ<SB>n</SB>(n is an arbitrary integer in a range of 1 or more and N or less, and N is an integer in a range of 2 or more) emitted from each light source 111<SB>n</SB>, which is provided inside a first station 110 are multiplexed by an optical multiplexer 112 and then amplified simultaneously with an optical amplifier 113. The optical signals of the wavelengths λ<SB>1</SB>to λ<SB>N</SB>amplified with the optical amplifier 113 are demultiplexed to a first channel flux Ch<SB>1</SB>and a second channel flux Ch<SB>2</SB>with an optical demultiplexer 114; the optical signals of the first channel flux Ch<SB>1</SB>are transmitted to an optical fiber transmitting path 131; and the optical signals of the second channel flux Ch<SB>2</SB>are transmitted to an optical fiber transmitting path 132. The optical signals of the first channel flux Ch<SB>1</SB>which has propagated through the optical fiber transmitting path 131 and the optical signals of the second channel flux Ch<SB>2</SB>which has propagated through the optical fiber transmitting path 132 are respectively inputted to an optical multiplexer 121 inside a second station 120 for multiplexing with the optical multiplexer 121 and bundle amplification with the optical amplifier 122. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical transmission system and an optical transmission method for multiplexing multi-wavelength signal light and transmitting the multiplexed signal light to an optical fiber transmission line.

  2. Description of the Related Art A wavelength division multiplexing (WDM) optical transmission system multiplexes multi-wavelength signal light and transmits it to an optical fiber transmission line, and can transmit and receive a large amount of information at high speed. Further, in an optical transmission system, an optical amplifier that amplifies signal light is used in order to compensate for a loss caused by signal light during transmission through an optical fiber transmission line.

  For example, in the invention disclosed in Patent Document 1, an optical amplifier is provided for each optical fiber transmission line connected to each of the input side and output side of the optical space switch. That is, the multi-wavelength WDM signal light propagating through the optical fiber transmission line on the input side is amplified by an optical amplifier provided corresponding to the optical fiber transmission line and then input to the optical space switch. In addition, the TDM signal light having the same wavelength, which is combined and output after the paths are switched by the optical space switch, is provided corresponding to the optical fiber transmission line before being sent to the optical fiber transmission line on the output side. Amplified by an optical amplifier. Thereby, the optical signal that has been wavelength division multiplexing transmission is transmitted to another optical fiber as an optical signal of time division multiplexing transmission.

  In addition, the invention disclosed in Patent Document 2 changes the wavelength of a part of the signal light when the line needs to be changed, such as when a line is damaged by the optical path cross-connect device. The light path is switched. If there is no problem, basically, the same optical signal is transmitted through the same optical transmission line. In the WDM transmission, the invention disclosed in Patent Document 3 is based on the transmission distance between nodes or the number of optical amplifiers between nodes when the wavelength of the optical path between nodes is dynamically allocated according to traffic fluctuation. The number of wavelengths to be assigned is changed accordingly.

  In DWDM optical transmission, various research and development have been conducted in order to increase the wave number of signal light that can be transmitted through a single optical fiber transmission line (that is, to improve the degree of multiplexing). For example, Non-Patent Document 1 introduced an example of a transmission system that increases the density of 100 channel signals (channel spacing is 50 GHz) and transmits a 400 km length in a wide wavelength range such as C band + L band. In this system, large-capacity optical communication is achieved by arranging four ultra-wideband amplifiers that collectively amplify in both C and L bands at intervals of 90 km to 200 km.

JP-A-8-288905 JP 2000-115133 A JP 2000-174730 A

A. K. Srivastava, et al., "1 Tb / s Transmission of 100 WDM 10 Gb / s Channels Over400km of TrueWaveTM Fiber", OFC'98, PD10 (1998)

  In an optical communication system that needs to use an optical amplifier, various problems are assumed in order to increase the capacity of a signal to be transmitted while adopting wavelength multiplexing. First, the wavelength band in which a signal exists is limited by the amplification band of the optical amplifier to be used. In order to further expand the wavelength band in which a signal exists, a plurality of optical amplifiers having different amplification bands are used. When the amplification band is determined to be a specific wavelength range depending on the optical amplifier to be used, and when aiming at a larger capacity, the number of channels is increased or the bit rate per channel is increased. . However, when using a single optical fiber transmission line that is housed in a cable or the like and increasing the bit rate per channel, it is usually necessary to increase the occupied band of that channel. When the number of channels is increased and the bit rate is increased, the problem of limiting the amplification band eventually occurs.

  When the channel interval is narrowed, the transmission characteristics of the wavelength division multiplex transmission signal are deteriorated due to nonlinear phenomena in the optical fiber, particularly four-wave mixing. For this reason, there are restrictions that the input power cannot be increased and the span length cannot be increased. In order to solve the above problems, the optical amplifier transmission line interval, the so-called span length, is shortened, or an expensive optical signal processing device is used to perform complex signal processing, while maintaining the span length. A response such as improving the quality characteristics required for the signal is required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical transmission system and an optical transmission method that can have a simple configuration.

  An optical transmission system according to the present invention includes (1) an optical amplifying unit that amplifies and outputs a plurality of channels of signal light, and (2) a plurality of channels of signal light output from the optical amplifying unit. An optical demultiplexing means for demultiplexing the first channel bundle and the second channel bundle, and separately outputting the demultiplexed signal light of the first channel bundle and the signal light of the second channel bundle; and (3) optical demultiplexing A first optical fiber transmission line for transmitting the signal light of the first channel bundle output from the means; and (4) a second optical fiber for transmitting the signal light of the second channel bundle output from the optical demultiplexing means. A high-speed and large-capacity signal light is transmitted as signal light of a plurality of channels.

  According to the optical transmission system of the present invention, after the multi-wavelength signal light is collectively amplified by the optical amplifying means, the multi-wavelength signal light is divided into the first channel bundle and the first channel bundle by the optical demultiplexing means. The demultiplexed signal light of the first channel bundle is transmitted to the first optical fiber transmission line, and the signal light of the second channel bundle is transmitted to the second optical fiber transmission line. As a result, the load required for the optical signal is reduced, and a simple and inexpensive system configuration can be achieved.

  In the optical transmission system according to the present invention, it is preferable that each channel of the first channel bundle and each channel of the second channel bundle have a relationship in which wavelength positions are alternately arranged. In this case, particularly when performing high-density WDM optical transmission, it is possible to avoid deterioration due to nonlinear phenomenon of signal light having adjacent wavelength ranges.

  In the optical transmission system according to the present invention, (1) the optical amplifying means has a plurality of optical amplifiers that amplify the signal light of a plurality of channels for each wavelength band, and (2) the signals output from the plurality of optical amplifiers It is preferable to provide an optical multiplexer that combines the light and outputs the combined multi-wavelength signal light toward the optical demultiplexing means. This configuration is a configuration in the case of a station at a signal transmission end. In the case of a relay station, it is preferable to perform a pre-process of multiplexing the signal light of each channel bundle and then demultiplexing it into each wavelength band. As another form of optical amplification, (1) the optical amplifying means has a plurality of optical amplifiers for amplifying the signal light of a plurality of channels for each wavelength band, and (2) the demultiplexing means is the plurality of light The signal light output from each of the amplifiers is demultiplexed into a first channel bundle and a second channel bundle for each wavelength band by a plurality of interleavers, and the respective signal lights of the demultiplexed channel bundles are channel bundles. It is preferable to provide a first multiplexer and a second multiplexer that multiplex each time. This configuration is a configuration in the case of a station at a signal transmission end. In the case of the relay station, it is preferable to perform a pre-process of demultiplexing into each wavelength band for each channel bundle and then multiplexing the signal light of each channel bundle for each wavelength band. By these modes, even when the signal light wavelength band is expanded and it is difficult to cope with only one optical amplifier, a large amount of information can be amplified.

  In the optical transmission system according to the present invention, it is preferable that any part along the longitudinal direction of each of the first optical fiber transmission line and the second optical fiber transmission line is accommodated in a common optical cable. . In this case, it is not necessary to install a new optical cable when constructing the optical transmission system as described above, so that the optical transmission system is also inexpensive in this respect.

  The optical transmission system according to the present invention preferably includes path switching means for switching a destination optical fiber transmission line for outputting the signal light of each channel bundle demultiplexed by the optical demultiplexing means. In this case, the optical fiber transmission path to which the signal light of each channel bundle demultiplexed by the optical demultiplexing means is output is switched by the path switching means. Thereby, for example, when an abnormality such as a disconnection occurs in any one of the optical fiber transmission lines, the signal light in the wavelength band that has been sent to the optical fiber transmission line in which the abnormality has occurred is transmitted to the path switch. After path switching, the data is subsequently sent to another normal optical fiber transmission line. Therefore, it is suitable not only in terms of risk dispersion but also in terms of risk avoidance.

  In the optical transmission system according to the present invention, there is a spare optical fiber transmission line, and the path switching means is a spare optical fiber when an abnormality is observed in either the signal light of the first channel bundle or the second channel bundle. It is preferable to be able to switch to a transmission line. In this case, an optical fiber transmission line suitable for the signal light of the specific channel bundle can be selected according to the system situation related to the signal light of the specific channel bundle, so that stable transmission quality is ensured. be able to.

  In the optical transmission system according to the present invention, the optical demultiplexing means demultiplexes the third channel bundle in addition to the first channel bundle and the second channel bundle, and outputs the signal light of the third channel bundle separately. A third optical fiber transmission line for transmitting the signal light of the third channel bundle output from the wave means, and when an abnormality is observed in the signal light of the first channel bundle, the path switching means It is preferable that the transmission destination of the signal light of one channel bundle can be switched to the optical fiber transmission line having a margin of either the second optical fiber transmission line or the third optical fiber transmission line. As a countermeasure when an abnormality is observed in the signal light of the first channel bundle due to the first optical fiber transmission line, other currently used optical fiber transmission lines (for example, the second optical fiber transmission) Or a third optical fiber transmission line) to avoid anomalies. In addition, even when any one of the plurality of optical fiber transmission lines is disconnected, the signal light can be transmitted to another optical fiber transmission line, which is preferable in terms of risk dispersion.

  The optical transmission system according to the present invention separates the multi-wavelength signal light output from the optical amplifying means into a first wavelength range shorter than the predetermined wavelength and a second wavelength range longer than the predetermined wavelength by the optical demultiplexing means. It is preferable to wave. In this case, the optical demultiplexing means is simple and inexpensive. Further, as in the present embodiment, signal light is transmitted by being shared by each of a plurality of optical fiber transmission lines, so that signal light of all wavelengths in each of the first wavelength range and the second wavelength range can be transmitted through one transmission line. It is possible to suppress the occurrence of Raman gain tilt due to stimulated Raman scattering between signal lights having wavelengths that may occur in transmission.

  The optical transmission system according to the present invention is capable of switching the output optical fiber transmission path of the signal light in the specific wavelength range by the path switching means when any of the plurality of optical fiber transmission lines is broken. Is preferred. In this case, an optical fiber transmission line suitable for the signal light of the specific channel bundle can be selected according to the system situation related to the signal light of the specific channel bundle, so that stable transmission quality is ensured. be able to.

  The optical transmission system according to the present invention has a spare optical fiber transmission line, and the path switching means is a spare optical fiber when an abnormality is observed in one of the signal lights of the first channel bundle and the second channel bundle. It is preferable to be able to switch to a transmission line. In this case, by using a spare optical fiber transmission line, even if an abnormality occurs in one channel bundle, stable transmission quality is ensured without affecting the transmission quality of other channel bundles. Can do.

  In the optical transmission system according to the present invention, the optical demultiplexing means demultiplexes and outputs the signal light of the third channel bundle in addition to the first channel bundle and the second channel bundle, and outputs the signal light from the optical demultiplexing means. A third optical fiber transmission line that transmits the signal light of the three channel bundle, and the path switching means, when an abnormality is observed in the signal light of the third channel bundle, the first optical fiber transmission line and the second optical fiber transmission line; It is preferable that the transmission destination of the signal light of the third channel bundle can be switched to at least one of the optical fiber transmission lines. In this case, it is not necessary to prepare a spare optical fiber transmission line.

  As described above in detail, according to the present invention, after the multi-wavelength signal light is collectively amplified by the optical amplifying means, the multi-wavelength signal light is converted into the first channel bundle and the second channel by the optical demultiplexing means. The signal light of the demultiplexed first channel bundle is transmitted to the first optical fiber transmission line, and the signal light of the second channel bundle is transmitted to the second optical fiber transmission line. Is done. Thereby, it can be made inexpensive with a simple system configuration, and the control system can be simplified.

1 is a configuration diagram of an optical transmission system 1 according to a first embodiment. FIG. It is a figure explaining one example of the demultiplexing of the multiwavelength signal light by the optical demultiplexer 114 in the optical transmission system 1 and the optical transmission method which concern on 1st Embodiment. It is a figure explaining another example of the demultiplexing of the multi-wavelength signal light by the optical demultiplexer 114 in the optical transmission system 1 and the optical transmission method according to the first embodiment. It is a block diagram of the optical transmission system 2 which concerns on 2nd Embodiment. It is a block diagram of the 2nd station 220 of the optical transmission system 2 which concerns on 2nd Embodiment. It is a figure which shows the other structure of the 2nd station 220 of the optical transmission system 2 which concerns on 2nd Embodiment. It is a block diagram of the optical transmission system 3 which concerns on 3rd Embodiment. It is a figure explaining each wavelength range in the optical transmission system 3 concerning 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  (First embodiment)

First, a first embodiment of an optical transmission system and an optical transmission method according to the present invention will be described. FIG. 1 is a configuration diagram of an optical transmission system 1 according to the first embodiment. In the optical transmission system 1 shown in this figure, an optical fiber transmission path 131 and an optical fiber transmission path 132 are laid between a first station 110 and a second station 120. In the first station 110, N (N is an integer greater than or equal to 2; the same applies hereinafter) light source units 111 _{1 to} 111 _N , an optical multiplexer 112, an optical amplifier 113, and an optical demultiplexer 114 are provided. . In the second station 120, an optical multiplexer 121 and an optical amplifier 122 are provided. The optical fiber transmission line 131 and the optical fiber transmission line 132 are housed in a common optical cable at any part in the longitudinal direction.

Each light source unit 111 _n in the first station 110 outputs signal light having a wavelength λ _n (n is an arbitrary integer from 1 to N, and so on). The optical multiplexer 112 receives the signal light having the wavelength λ _n output from each light source unit 111 _n , combines them, and outputs them to the optical amplifier 113. The optical amplifier 113 receives the signal lights having the wavelengths λ _{1 to} λ _N that have been combined and output by the optical multiplexer 112, amplifies them, and outputs them to the optical demultiplexer 114. Then, the optical demultiplexer 114 receives the signal light having the wavelengths λ _{1 to} λ _N amplified and output by the optical amplifier 113, and divides them into the first channel bundle Ch ₁ and the second channel bundle Ch _2. The signal light of the first channel bundle Ch ₁ is sent out to the optical fiber transmission path 131, and the signal light of the second channel bundle Ch ₂ is sent out to the optical fiber transmission path 132.

The optical multiplexer 121 in the second station 120 inputs the signal light of the first channel bundle Ch ₁ that has propagated through the optical fiber transmission path 131 and reached the second channel that has propagated through the optical fiber transmission path 132 and reached. The signal light of the channel bundle Ch ₂ is also input, combined, and output to the optical amplifier 122. The optical amplifier 122 receives the signal lights having the wavelengths λ _{1 to} λ _N that are combined and output by the optical multiplexer 121, amplifies them, and outputs them.

The wavelengths λ _{1 to} λ _N are different from each other, and are included in, for example, the C band or the L band. Further, in this case, each of the optical amplifier 113 and the optical amplifier 122 includes an optical fiber (EDF: Erbium Doped Fiber) in which an Er element is added to the optical waveguide region as an optical amplification medium, and the EDF includes excitation light (wavelength). It is preferable to use an EDFA (Erbium Doped Fiber Amplifier) that amplifies signal light in this EDF by supplying a 0.98 μm band or a 1.48 μm band.

Next, the operation of the optical transmission system 1 according to the first embodiment will be described, and the optical transmission method according to the first embodiment will also be described. The signal light of wavelength λ _n output from each light source unit 111 _n in the first station 110 is multiplexed by the optical multiplexer 112 and is collectively amplified by the optical amplifier 113. A transmission signal light having the wavelength lambda ₁ to [lambda] _N by the optical amplifier 113 is the channel bundle Ch ₁ by the optical demultiplexer 114 and the second channel bundle Ch ₂ demultiplexed, the first channel bundle Ch ₁ The signal light is transmitted to the optical fiber transmission path 131, and the signal light of the second channel bundle Ch ₂ is transmitted to the optical fiber transmission path 132. The signal light of the first channel bundle Ch ₁ that has propagated through the optical fiber transmission line 131 and the signal light of the second channel bundle Ch ₂ that has propagated through the optical fiber transmission line 132 are respectively optical multiplexer 121 in the second station 120. Are combined by the optical multiplexer 121 and are collectively amplified by the optical amplifier 122. The multi-wavelength signal light output from the optical amplifier 122 is, for example, further sent to a subsequent optical fiber transmission line, or demultiplexed for each wavelength in the second station 120 and received. Note that the channel bundle may indicate the entire channel group in a predetermined wavelength band, or may indicate the entire channel group in which individual channels are discrete.

FIG. 2 is a diagram illustrating an example of demultiplexing of multi-wavelength signal light by the optical demultiplexer 114 in the optical transmission system 1 and the optical transmission method according to the first embodiment. FIG. 4A shows the wavelength of each signal light input to the optical demultiplexer 114. FIG. 4B shows the wavelength of each signal light included in the first channel bundle Ch ₁ (first wavelength region Λ ₁ ) transmitted from the optical demultiplexer 114 to the optical fiber transmission line 131. FIG. 4C shows the wavelength of each signal light included in the second channel bundle Ch ₂ (second wavelength region Λ ₂ ) transmitted from the optical demultiplexer 114 to the optical fiber transmission line 132. Here, N = 8 and λ ₁ <λ ₂ <λ ₃ <λ ₄ <λ ₅ <λ ₆ <λ ₇ <λ ₈ . In the example of demultiplexing shown in this figure, the signal light of the wavelengths λ _{1 to} λ ₈ output from the optical amplifier 113 includes a first wavelength band Λ ₁ (wavelengths λ _{1 to} λ ₄ shorter than a predetermined wavelength). ) And a second wavelength band Λ ₂ (including wavelengths λ _{5 to} λ ₈ ) longer than the predetermined wavelength. For convenience of explanation, an example of 8 waves has been described. However, in the present invention, wavelength multiplex transmission at a high density of several tens of waves or more is assumed.

FIG. 3 is a diagram illustrating another example of demultiplexing of multi-wavelength signal light by the optical demultiplexer 114 in the optical transmission system 1 and the optical transmission method according to the first embodiment. FIG. 4A shows the wavelength of each signal light input to the optical demultiplexer 114. FIG. 4B shows the wavelength of each signal light included in the first channel bundle Ch ₁ transmitted from the optical demultiplexer 114 to the optical fiber transmission line 131. FIG. 4C shows the wavelength of each signal light included in the second channel bundle Ch ₂ transmitted from the optical demultiplexer 114 to the optical fiber transmission line 132. Again, N = 8 and λ ₁ <λ ₂ <λ ₃ <λ ₄ <λ ₅ <λ ₆ <λ ₇ <λ ₈ . In the example of demultiplexing shown in this figure, the signal light of wavelengths λ _{1 to} λ ₈ output from the optical amplifier 113 is a first channel bundle Ch ₁ (wavelengths λ ₁ , λ ₃ , λ ₅ and λ ₇ ), and a second channel bundle Ch ₂ (wavelengths λ ₂ , λ ₄ , λ ₆ and λ ₈ ) including a plurality of other discontinuous partial wavelength bands between them. Including). For convenience of explanation, an example of 8 waves has been described. However, in the present invention, wavelength multiplex transmission at a high density of several tens of waves or more is assumed.

As described above, according to the optical transmission system 1 and the optical transmission method according to the present embodiment, after multi-wavelength signal light is collectively amplified by one optical amplifier 113, the multi-wavelength signal light is optically demultiplexed. The first channel bundle Ch ₁ and the second channel bundle Ch ₂ are demultiplexed by 114, the signal light of the first channel bundle Ch ₁ is sent to the optical fiber transmission line 131, and the signal of the second channel bundle Ch ₂ is transmitted. Light is sent to the optical fiber transmission line 132. Thereby, the optical transmission system 1 according to the present embodiment can be made inexpensive with a simple configuration, and the control system can be made simple.

  Further, when the optical fiber transmission path 131 and the optical fiber transmission path 132 housed in a common optical cable are used, it is necessary to lay a new optical cable separately when constructing the optical transmission system as described above. In this respect, the optical transmission system is inexpensive.

As described with reference to FIG. 2, the optical demultiplexer 114 converts the multi-channel signal light into the first wavelength band Λ ₁ (including wavelengths λ _{1 to} λ ₄ ) and the second wavelength band Λ ₂ (wavelengths λ _{5 to} λ ₈ ), the optical demultiplexer 114 has a simple configuration and is inexpensive. Wavelengths that may occur when signal light of all wavelengths is transmitted through a single transmission line by transmitting the signal light to each of a plurality of optical fiber transmission lines as in the present embodiment (for example, The occurrence of Raman gain tilt due to stimulated Raman scattering between the signal lights (λ ₁ and λ ₈ ) can be suppressed. In addition, since the transmission is distributed over a plurality of optical fiber transmission lines, the risk of disconnection is reduced, and there is a spare optical fiber transmission line. If any of the optical fiber transmission lines breaks, switching to the spare optical fiber transmission line is possible. If this is possible, it is also suitable in terms of risk dispersion. By using an optical fiber transmission line that is optimal for transmission for each wavelength band, the quality characteristics required for the optical signal are alleviated, and the load on the optical signal processing device is reduced.

As described with reference to FIG. 3, the multi-wavelength signal light is transmitted by the optical demultiplexer 114 to the first channel bundle Ch ₁ (including wavelengths λ ₁ , λ ₃ , λ ₅ and λ ₇ ) and the second channel bundle Ch _2. In the case of demultiplexing into wavelengths (including wavelengths λ ₂ , λ ₄ , λ ₆ and λ ₈ ), particularly when performing high-density WDM optical transmission, nonlinearity such as four-wave mixing between adjacent signal light wavelengths This is preferable because deterioration can be avoided.

  Further, when an EDFA is used as each of the optical amplifier 113 and the optical amplifier 122, the optical demultiplexer 114 is simple and inexpensive. In contrast to FIG. 2, when amplifying signal light in a limited wavelength range and high channel density, these optical amplifiers 113 and 122 are inexpensive in price per wavelength range, and high-channel-density signal light is used. Since amplification can be performed by one amplifier, it is more advantageous than amplification in a plurality of wavelength bands. In addition, if the transmission wavelength range is the same, the same type of optical fiber can be used for the optical fiber transmission line, and if an abnormality occurs in the optical fiber transmission line, another spare optical fiber transmission line in the optical cable is used. It is safe to use. In addition, when the signal light is transmitted at a low channel density, the required number of optical fiber transmission lines increases, but the number of repeaters can be reduced by increasing the span length of the optical fiber transmission line. Therefore, it is suitable as an optical transmission system. It becomes possible to reduce the channel density of the signal light transmitted to the optical fiber transmission line, the quality characteristics required for the optical signal will be relaxed, and the load on the optical signal processing equipment will be reduced. As an optical transmission system Is preferred.

  (Second Embodiment)

  Next, a second embodiment of the optical transmission system and the optical transmission method according to the present invention will be described. FIG. 4 is a configuration diagram of the optical transmission system 2 according to the second embodiment. In the optical transmission system 2 shown in this figure, optical fiber transmission lines 231 to 233 are laid between a first station 210 and a second station 220. FIG. 5 is a configuration diagram of the second station 220 of the optical transmission system 2 according to the second embodiment.

In the first station 210, N light source units 211 _{1 to} 211 _N , an optical multiplexer 212, an optical amplifier 213, an optical demultiplexer 214, and a path switch 215 are provided. In the second station 220, an optical multiplexer 221, an optical amplifier 222, and an optical demultiplexer 223 are provided. Also, any part along the longitudinal direction of each of the optical fiber transmission lines 231 to 233 is accommodated in a common optical cable.

Each light source unit 211 _n in the first station 210 outputs signal light having a wavelength λ _n (n is an arbitrary integer of 1 or more and N or less, and so on). The optical multiplexer 212 receives the signal light having the wavelength λ _n output from each light source unit 211 _n , combines them, and outputs them to the optical amplifier 213. The optical amplifier 213 receives the signal lights having the wavelengths λ _{1 to} λ _N that are combined and output by the optical multiplexer 212, amplifies them together, and outputs them to the optical demultiplexer 214. The optical demultiplexer 214 receives the signal lights having wavelengths λ _{1 to} λ _N that are amplified and output by the optical amplifier 213, and inputs them into the first channel bundle Ch ₁ , the second channel bundle Ch _2, and the third channel bundle. The signal light of each channel bundle is output to the path switch 215 after being demultiplexed into Ch ₃ . Then, the path switch 215 inputs the signal light of each of the first channel bundle Ch ₁ , the second channel bundle Ch ₂ and the third channel bundle Ch ₃ output after being demultiplexed by the optical demultiplexer 214, The optical fiber transmission line to which the signal light of the channel bundle is to be transmitted is selected from the optical fiber transmission lines 231 to 233, and the signal light of each channel bundle is transmitted to the selected optical fiber transmission line.

The optical multiplexer 221 in the second station 220 receives the signal light of each channel bundle that has arrived after propagating through the optical fiber transmission lines 231 to 233, combines them, and outputs them to the optical amplifier 222. The optical amplifier 222 receives the signal lights having the wavelengths λ _{1 to} λ _N that are combined and output by the optical multiplexer 221, amplifies them collectively, and outputs them to the optical demultiplexer 223. Then, the optical demultiplexer 223 receives the signal lights having the wavelengths λ _{1 to} λ _N that are amplified and output by the optical amplifier 222, and inputs them into the first channel bundle Ch ₁ , the second channel bundle Ch _2, and the third channel bundle. The signal light of the first channel bundle Ch ₁ is demultiplexed into the channel bundle Ch ₃ , the signal light of the first channel bundle Ch ₁ is sent out to the optical fiber transmission path 241, the signal light of the second channel bundle Ch ₂ is sent out to the optical fiber transmission path 242, The signal light of the 3-channel bundle Ch ₃ is sent to the optical fiber transmission line 243.

The wavelengths λ _{1 to} λ _N are different from each other, and are included in, for example, the C band or the L band. In this case, each of the optical amplifier 213 and the optical amplifier 222 is preferably an EDFA including an EDF as an optical amplification medium. Further, each of the first channel bundle Ch ₁ , the second channel bundle Ch ₂ and the third channel bundle Ch ₃ is in a wavelength region which is divided with a certain predetermined wavelength as a boundary, as in the case shown in FIG. There may be. In this case, if the magnitude relationship of each wavelength is λ ₁ <λ ₂ <λ ₃ <... <Λ _N , for example, the first wavelength region Λ ₁ includes wavelengths λ _{1 to} λ _p and the second wavelength region Λ ₂ includes wavelengths λ _{p + 1 to} λ _q , and the third wavelength region Λ ₃ includes wavelengths λ _{q + 1 to} λ _N (where p <q <N). Alternatively, similarly to the case shown in FIG. 3, it may include a plurality of discontinuous partial wavelength regions. In this case, if the magnitude relationship of each wavelength is λ ₁ <λ ₂ <λ ₃ <... <Λ _N , for example, the first channel bundle Ch ₁ includes the wavelength λ _{4m + 1} , and the second channel bundle Ch ₂ includes It includes the wavelength lambda _{4m + 3,} the third channel bundle Ch ₃ includes channel bundle _{Ch 31} (wavelength lambda _{4m + 2)} and channel flux _{Ch 32 (λ 4m + 4)} . However, m is each integer greater than or equal to 0 and less than (N / 4).

Next, the operation of the optical transmission system 2 according to the second embodiment will be described, and the optical transmission method according to the second embodiment will also be described. The signal light of wavelength λ _n output from each light source unit 211 _n in the first station 210 is multiplexed by the optical multiplexer 212 and is collectively amplified by the optical amplifier 213. The signal light having the wavelengths λ _{1 to} λ _N amplified by the optical amplifier 213 is demultiplexed by the optical demultiplexer 214 into the first channel bundle Ch ₁ , the second channel bundle Ch _2, and the third channel bundle Ch _3. . Then, the signal light of each channel bundle demultiplexed by the optical demultiplexer 214 is sent to one of the optical fiber transmission lines 231 to 233 via the path switch 215.

When abnormality is found in the signal light of the first channel bundle Ch ₁ due to the path setting in the path switch 215 or when the optical fiber transmission line 231 is defective, for example, the first channel bundle Ch ₁ (λ _{4m + 1} ) and the first channel bundle Ch ₁ The signal light of each of the two channel bundles Ch ₂ (λ _{4m + 3} ) is sent to the optical fiber transmission line 232, and the signal light of the third channel bundle Ch ₃ is sent to the optical fiber transmission line 233. When the problem of the optical fiber transmission line 231 is resolved, for example, the signal light of the first channel bundle Ch ₁ that has been sent to the optical fiber transmission line 232 is switched by the path switching in the path switch 215. Thereafter, it is sent to the optical fiber transmission line 231. Further, when there is a spare optical fiber transmission line, the signal light transmitted to the defective optical fiber transmission line may be changed to a spare transmission line by the path switch 215. Further, in the case where the third channel bundle Ch is transmitted to the optical fiber transmission line 233, there is a problem, and only the channel bundle Ch ₃₂ can be used by switching the spare optical fiber transmission line. is there.

The signal light of each channel bundle propagated through any one of the optical fiber transmission lines 231 to 233 is input to the optical multiplexer 221 in the second station 220, and is multiplexed by the optical multiplexer 221, It is amplified in a lump. Multi-wavelength signal light outputted from the optical amplifier 222, it is the first channel bundle Ch ₁ by the optical demultiplexer 223 and the second channel bundle Ch ₂ and third channel bundle Ch ₃ demultiplexed first channel The signal light of the bundle Ch ₁ is sent to the optical fiber transmission line 241, the signal light of the second channel bundle Ch ₂ is sent to the optical fiber transmission line 242, and the signal light of the third channel bundle Ch ₃ is sent to the optical fiber transmission line 243. Is sent to.

Note that the second station 220 may have other configurations. FIG. 6 is a diagram illustrating another configuration of the second station 220 of the optical transmission system 2 according to the second embodiment. In the second station 220 shown in this figure, an optical multiplexer 224, an optical amplifier 225 ₁ , an optical amplifier 225 ₂ , an optical demultiplexer 226, and a light receiving unit 227 are provided. The optical multiplexer 224 receives the signal light of each channel flux reached propagating through the respective optical fiber transmission path 232 and optical fiber transmission line 233, and outputs these multiplexed to the optical amplifier 225 _2. The optical amplifier 225 _2, are multiplexed by the optical multiplexer 224 receives the signal light of multiple wavelengths outputted, and outputs them collectively amplifying the optical demultiplexer 226. The optical demultiplexer 226 is amplified by the optical amplifier 225 ₂ receives the signal light of multiple wavelengths output demultiplexes them to each channel bundle optical fiber transmission line 242 and the optical fiber transmission path 243 To any of the above. Further, the optical amplifier 225 ₁ is been propagated through the optical fiber transmission line 231 receives the signal light of the wavelength region has reached, and outputs them collectively amplified by the light receiving portion 227. Then, the light receiving portion 227 is amplified by the optical amplifier 225 ₁ inputs the multi-wavelength signal light outputted to the light receiving and demultiplexing them for each wavelength.

  The optical transmission system 2 and the optical transmission method according to the second embodiment have the same effects as the effects of the first embodiment, and also have the following effects. In other words, in the second embodiment, the path switch 215 provided in the first station 210 selects the optical fiber transmission path to which the signal light of each channel bundle is to be sent from the optical fiber transmission paths 231 to 233. Then, the signal light of each channel bundle is transmitted to the selected optical fiber transmission line. For example, when an abnormality such as disconnection occurs in any one of the optical fiber transmission lines 231 to 233, the signal of the channel bundle that has been sent to the optical fiber transmission line in which the abnormality has occurred. The light is sent to another normal optical fiber transmission line by path switching in the path switch 215. Therefore, the optical transmission system 2 and the optical transmission method according to the present embodiment are suitable not only for risk dispersion but also for risk avoidance.

  Further, it is preferable that the path switching unit 215 can switch the destination optical fiber transmission line that outputs the signal light of the specific channel bundle. In this case, an optical fiber transmission line suitable for the signal light of the specific channel bundle can be selected according to the system situation related to the signal light of the specific channel bundle, so that stable transmission quality is ensured. be able to. For example, it is possible to always ensure stable transmission quality by transmitting the signal light of the channel bundle whose transmission characteristics are deteriorated due to nonlinear degradation to another optical fiber transmission line with little nonlinear degradation.

  (Third embodiment)

Next, a third embodiment of the optical transmission system and the optical transmission method according to the present invention will be described. FIG. 7 is a configuration diagram of an optical transmission system 3 according to the third embodiment. In the optical transmission system 3 shown in this figure, an optical fiber transmission line 331 and an optical fiber transmission line 332 are laid between a first station 310 and a second station 320. Within the first station 310, there are M (M is an integer of 2 or more; the same shall apply hereinafter) C-band light source units 311 _{C, 1 to} 311 _{C, M} and N (N is an integer of 2 or more. L band light source section 311 _{L, 1 to} 311 _{L, N} , C band optical multiplexer 312 _C , L band optical multiplexer 312 _L , C band optical amplifier 313 _C , L band optical amplifier 313 _L , an optical multiplexer 314 and an optical demultiplexer 315 are provided. In addition, it is preferable that any part along the longitudinal direction of each of the optical fiber transmission line 331 and the optical fiber transmission line 332 is accommodated in a common optical cable.

Each light source unit 311 _{C, m} in the first station 310 outputs signal light having a wavelength λ _{C, m} (m is an arbitrary integer from 1 to M, and so on). The optical multiplexer 312 _C, each light source unit _{311 C,} enter the signal light output wavelength lambda _{C, m} from _m, and outputs them multiplexed with the optical amplifier 313 _C. The optical amplifier 313 _C receives the signal lights having the wavelengths λ _{C, 1 to} λ _{C, M} that have been combined and output by the optical multiplexer 312 _C, amplifies them together, and outputs them to the optical multiplexer 314. To do. The wavelengths λ _{C, 1 to} λ _{C, M} are different from each other and are included in the C band Λ _C. The optical amplifier 313 _C is suitably a EDFA including EDF as an optical amplification medium.

Each light source unit 311 _{L, n} outputs signal light having a wavelength λ _{L, n} (n is an arbitrary integer from 1 to N, and so on). The optical multiplexer 312 _L receives the signal light of the wavelength λ _{L, n} output from each light source unit 311 _{L, n} , combines them, and outputs them to the optical amplifier 313 _L. The optical amplifier 313 _L receives the signal lights having the wavelengths λ _{L, 1 to} λ _{L, N that} are combined and output by the optical multiplexer 312 _L, amplifies them collectively, and outputs them to the optical multiplexer 314. To do. The wavelengths λ _{L, 1 to} λ _{L, N} are different from each other and are included in the L band Λ _L. The optical amplifier 313 _L is preferably an EDFA including an EDF as an optical amplification medium.

The optical multiplexer 314, wavelength was amplified output by the optical amplifier _{313 C λ C, 1 ~λ C} , inputs the signal light _M, the optical amplifier 313 wavelength output is amplified by the _L lambda _{L, 1 to} λ _{L, N} signal lights are input, combined, and output to the optical demultiplexer 315. The optical demultiplexer 315 inputs the signal lights of the multi-wavelengths λ _{C, 1 to} λ _{C, M} and λ _{L, 1 to} λ _{L, N that} are combined and output by the optical multiplexer 314 _, and inputs them. The first channel bundle Ch ₁ and the second channel bundle Ch ₂ are demultiplexed to send the signal light of the first channel bundle Ch ₁ to the optical fiber transmission line 331, and the signal light of the second channel bundle Ch ₂ is transmitted as light. The data is sent to the fiber transmission line 332.

The second station 320 inputs the signal light of the first channel bundle Ch ₁ that has propagated through the optical fiber transmission line 331 and has reached the signal of the second channel bundle Ch ₂ that has propagated through the optical fiber transmission line 332 and reached. Light is also input and combined, and then demultiplexed for each wavelength band, and amplified in a lump for each wavelength band as in the first station 310. In the second station 320, for example, the multi-wavelength signal light collectively amplified for each wavelength band is demultiplexed and received for each wavelength. When the second station 320 transmits signal light to the next stage as in the first station, the multi-wavelength signal light collectively amplified for each wavelength band is multiplexed by a multiplexer, The signals are demultiplexed into the first channel bundle Ch ₁ and the second channel bundle Ch ₂ and output to the next optical fiber transmission line.

FIG. 8 is a diagram illustrating each wavelength region in the optical transmission system 3 according to the third embodiment. FIG. 4A shows the wavelengths λ _{C, 1 to} λ _{C, M} of each signal light of the C band Λ _C amplified by the optical amplifier 313 _C. FIG. 2B shows the wavelengths λ _{L, 1 to} λ _{L, N} of each signal light of the L band Λ _L amplified by the optical amplifier 313 _L. FIG. 4C shows the wavelengths λ _{C, 2p + 1} and λ _{L, 2q + 1} of each signal light of the first channel bundle Ch ₁ output from the optical demultiplexer 315. FIG. FIG. 4D shows the wavelengths λ _{C, 2p + 2} and λ _{L, 2q + 2} of each signal light of the second channel bundle Ch ₂ output from the optical demultiplexer 315. However, p is each integer of 0 or more and less than (M / 2), and q is each integer of 0 or more and less than (N / 2).

As shown in this figure, one optical amplifier 313 _C collectively amplifies a C band Λ _C (including wavelengths λ _{C, 1 to} λ _{C, M} ) shorter than a predetermined wavelength, and one optical amplifier 313 _L collectively amplifies an L band Λ _L (including wavelengths λ _{L, 1 to} λ _{L, N} ) longer than the predetermined wavelength. Therefore, each of the optical amplifier 313 _C and the optical amplifier 313 _L can have an appropriate configuration according to the band to be amplified, and the signal light in that band can be amplified with high efficiency.

Further, the optical demultiplexer 315 inputs the signal light of the wavelengths λ _{C, 1 to} λ _{C, M} and λ _{L, 1 to} λ _{L, N} and receives the first channel including a plurality of discontinuous partial wavelength regions. Bundle Ch ₁ (including wavelengths λ _{C, 1} , λ _{C, 3} , λ _{C, 5} , λ _{C, 7} , λ _{L, 1} , λ _{L, 3} , λ _{L, 5} and λ _{L, 7} ) and these A second channel bundle Ch ₂ (wavelengths λ _{C, 2} , λ _{C, 4} , λ _{C, 6} , λ _{C, 8} , λ _{L, 2} , λ _{L, 4} , λ _{L, 6} and λ _{L, 8} ), and the signal light of the first channel bundle Ch ₁ is sent to the optical fiber transmission line 331, and the second channel bundle Ch ₂ The signal light is sent to the optical fiber transmission line 332. Accordingly, when performing high-density WDM optical transmission, it is possible to avoid nonlinear degradation between adjacent signal light wavelengths.

Next, the operation of the optical transmission system 3 according to the third embodiment will be described, and the optical transmission method according to the third embodiment will also be described. The signal light of the wavelength λ _{C, m} output from each light source unit 311 _{C, m} in the first station 310 is multiplexed by the optical multiplexer 312 _C and is collectively amplified by the optical amplifier 313 _C. In addition, the signal light having the wavelength λ _{L, n} output from each light source unit 311 _{L, n} is multiplexed by the optical multiplexer 312 _L and is collectively amplified by the optical amplifier 313 _L. The signal light of wavelengths λ _{C, 1 to} λ _{C, M} amplified by the optical amplifier 313 _C and the signal light of wavelengths λ _{L, 1 to} λ _{L, N} amplified by the optical amplifier 313 _L are optical multiplexers. After being multiplexed by 314, the optical demultiplexer 315 is demultiplexed into the first channel bundle Ch ₁ and the second channel bundle Ch _2, and the signal light of the first channel bundle Ch ₁ is sent to the optical fiber transmission line 331. The signal light of the second channel bundle Ch ₂ is sent out to the optical fiber transmission line 332. The signal light of the first channel bundle Ch ₁ propagated through the optical fiber transmission line 331 and the signal light of the second channel bundle Ch ₂ propagated through the optical fiber transmission line 332 reach the second station 320, and this After being multiplexed at the second station 320, it is amplified at once, for example, demultiplexed for each channel bundle and sent to the optical fiber transmission line at the subsequent stage. The received signal is amplified in the second station 320 without being combined or after being combined, and is received after being demultiplexed for each wavelength.

The optical transmission system 3 and the optical transmission method according to the third embodiment have the same effects as the effects of the first embodiment, and also have the following effects. That is, in the third embodiment, the wavelength of the C-band lambda _C lambda _C, 1 to [lambda] _C, with C-band optical amplifier 313 for amplifying the signal light _{M C} are provided, L-band lambda wavelength of _L lambda _{L, 1} to [lambda] _L, by provided also signal the L-band optical amplifier 313 for amplifying the light _L of _N, it is a signal wavelength band is expanded, is possible to transmit a large amount of information in a wider wavelength range it can. Each of the optical amplifier 313 _C and the optical amplifier 313 _L can have an appropriate configuration according to the band to be amplified, and can amplify the signal light in that band with high efficiency. Further, the optical demultiplexer 315 causes the first channel bundle Ch ₁ including a plurality of discontinuous partial wavelength regions and the second channel bundle Ch ₂ including other discontinuous partial wavelength regions between them. The signal light of the first channel bundle Ch ₁ is sent to the optical fiber transmission line 331 and the signal light of the second channel bundle Ch ₂ is sent to the optical fiber transmission line 332. Accordingly, when performing high-density WDM optical transmission, it is possible to avoid nonlinear degradation between adjacent signal light wavelengths.

In FIG. 7, the optical signal amplified and output by the optical amplifier 313 _C and the optical amplifier 313 _L is once output to the optical multiplexer 314 and then input to the optical demultiplexer 315. The order of the optical multiplexer 314 and the optical demultiplexer 315 may be switched. As an optical demultiplexer, two interleavers are used, and the signal light from the optical amplifier 313 _C is transmitted by the interleaver 1 to a wavelength band Λ _c1 (wavelengths λ _{C, 1} , λ _{C, 3} ,..., Λ _{C, 2p + 1} ) And wavelength band Λ _c2 (wavelength λ _{C, 2} , λ _{C, 4} ,..., Λ _{C, 2p + 2} ), and the signal light from the optical amplifier 313 _L is interleaved by the interleaver 2 and the wavelength band Λ _L1 (wavelength λ _{L, 1} , λ _{L, 3} ,..., λ _{L, 2q + 1} ) and wavelength band Λ _L2 (wavelengths λ _{L, 2} , λ _{L, 4} ,..., λ _{L, 2q + 2} ). Thereafter, the demultiplexed signal light is combined with the signal light in the wavelength band Λ _{c1 and} the signal light in the wavelength band Λ _L1 by the multiplexer 1 using two multiplexers, and the signal light in the wavelength band Λ _c2 And signal light in the wavelength band Λ _L2 are multiplexed by the multiplexer 2 and output to the optical fiber transmission lines 331 and 332, respectively. The signal light combined by the multiplexers 1 and 2 is a combination of signal light in the wavelength band Λ _c1 and signal light in the wavelength band Λ _L2 , signal light in the wavelength band Λ _c2 , and signal light in the wavelength band Λ _L1 . A combination of these may be used.

  The second station 320 corresponding to the relay station amplifies signal light from a plurality of optical fiber transmission lines at the same time as in FIG. 6, but each signal light has a wavelength band including C band and L band. Therefore, it is different from FIG. In order to transmit the amplified signal light to the subsequent optical fiber transmission line in the same manner as in FIG. 6, the optical signal light from the optical fiber transmission lines 331 and 332 is temporarily used for each optical fiber by using a duplexer. It is necessary to take a measure of demultiplexing the C-band and L-band from the transmission path and multiplexing the optical signal light from the optical fiber transmission paths 331 and 332 for each C-band and L-band. Thus, the optical signals combined for each band are collectively amplified for each band, combined in the same manner as in FIG. 7, and separated by an interleaver to form different channel sides, and for each channel bundle. Output to a different optical fiber transmission line.

  The first embodiment, the second embodiment, and the third embodiment are not limited to the C band or the L band, and can be applied to other bands such as the S band. The wavelength region may be a wavelength region that spans a plurality of bands such as the S band, the C band, and the L band. Also, in one transmission path section, signal light in different wavelength ranges is transmitted for each optical fiber transmission path, and in other transmission path sections, signal light in different channel bundles that are demultiplexed by an interleaver for each optical fiber transmission path. It may be transmitted.

  DESCRIPTION OF SYMBOLS 1-3 ... Optical transmission system, 110 ... 1st station, 111 ... Light source part, 112 ... Optical multiplexer, 113 ... Optical amplifier, 114 ... Optical demultiplexer, 120 ... 2nd station, 121 ... Optical multiplexer, 122 DESCRIPTION OF SYMBOLS ... Optical amplifier 131, 132 ... Optical fiber transmission line 210 ... First station 211 ... Light source unit 212 ... Optical multiplexer 213 ... Optical amplifier 214 ... Optical demultiplexer 215 ... Path switcher 220 ... 2nd station, 221 ... optical multiplexer, 222 ... optical amplifier, 223 ... optical demultiplexer, 224 ... optical multiplexer, 225 ... optical amplifier, 226 ... optical demultiplexer, 227 ... light receiving unit, 231-233 ... light Fiber transmission path, 310 ... 1st station, 311 ... Light source unit, 312 ... Optical multiplexer, 313 ... Optical amplifier, 314 ... Optical multiplexer, 315 ... Optical demultiplexer, 320 ... 2nd station, 331, 332 ... Optical Fiber transmission line.

Claims (12)

An optical transmission system that transmits high-speed, large-capacity signal light as signal light of multiple channels,
Optical amplification means for amplifying and outputting the signal light of the plurality of channels;
A plurality of channels of signal light amplified and output by the optical amplifying means are demultiplexed into a first channel bundle and a second channel bundle, and the demultiplexed signal light of the first channel bundle and the second channel bundle. An optical demultiplexing means for separately outputting the signal light of the channel bundle;
A first optical fiber transmission line for transmitting the signal light of the first channel bundle output from the optical demultiplexing means;
And a second optical fiber transmission line for transmitting the signal light of the second channel bundle output from the optical demultiplexing means.   2. The optical transmission system according to claim 1, wherein the channels of the first channel bundle and the channels of the second channel bundle have a relationship in which wavelength positions are alternately arranged. The optical amplification means includes a plurality of optical amplifiers that amplify the signal light of the plurality of channels for each wavelength band,
An optical multiplexer is provided that combines the signal lights output from the plurality of optical amplifiers and outputs the combined signal lights of the plurality of channels toward the optical demultiplexing means. 2. The optical transmission system according to 2. The optical amplification means has a plurality of optical amplifiers for amplifying the signal light of the plurality of channels for each wavelength band,
The demultiplexing unit demultiplexes the signal light output from each of the plurality of optical amplifiers into a first channel bundle and a second channel bundle for each wavelength band by a plurality of interleavers. The optical transmission system according to claim 2, further comprising a first multiplexer and a second multiplexer that multiplexes the signal light of each channel bundle for each channel bundle.   2. The optical transmission according to claim 1, wherein any one of the first optical fiber transmission line and the second optical fiber transmission line along a longitudinal direction is accommodated in a common optical cable. system.   3. The optical transmission system according to claim 2, further comprising path switching means for switching a destination optical fiber transmission path for outputting the signal light of each channel bundle demultiplexed by the optical demultiplexing means. Have a spare optical fiber transmission line,
7. The light according to claim 6, wherein the path switching means switches to the spare optical fiber transmission line when an abnormality is observed in any of the signal light of the first channel bundle and the second channel bundle. Transmission system. The optical demultiplexing means demultiplexes the third channel bundle in addition to the first channel bundle and the second channel bundle, and separately outputs the signal light of the third channel bundle,
A third optical fiber transmission line for transmitting the signal light of the third channel bundle output from the optical demultiplexing means;
When an abnormality is observed in the signal light of the first channel bundle, the path switching means sets the destination of the signal light of the first channel bundle as the second optical fiber transmission line or the third optical fiber transmission line. 7. The optical transmission system according to claim 6, wherein the optical fiber transmission line can be switched to either one of which has a margin.   The signal light of the first channel bundle is included in a first wavelength band, and the signal light of the second channel bundle is included in a second wavelength band different from the first wavelength band. The optical transmission system according to 1.   10. The optical transmission system according to claim 9, further comprising path switching means for switching a destination optical fiber transmission line for outputting the signal light of each wavelength band demultiplexed by the optical demultiplexing means. Have a spare optical fiber transmission line,
10. The light according to claim 9, wherein the path switching means switches to the spare optical fiber transmission line when an abnormality is observed in one of the signal lights of the first channel bundle and the second channel bundle. Transmission system. The optical demultiplexing means demultiplexes and outputs the signal light of the third channel bundle in addition to the first channel bundle and the second channel bundle,
A third optical fiber transmission line for transmitting the signal light of the third channel bundle output from the optical demultiplexing means;
When an abnormality is observed in the signal light of the first channel bundle, the path switching means sets the destination of the signal light of the first channel bundle as the second optical fiber transmission line and the third optical fiber transmission line. The optical transmission system according to claim 9, wherein the optical transmission system can be switched to one of the following.

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