JP2007028672A - Long wavelength channel control system in wide-band wdm optical fiber transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical amplifier unit used in a system generating power movement from a comparatively short wavelength signal to a comparatively long wavelength signal. <P>SOLUTION: An optical amplifier unit comprises: an amplifier stage coupled to an optical transmission medium; a monitor for monitoring the state of a first band; and a pump light source configured to supply at least one first pump light to the optical transmission medium based on the monitored state of the first band, and to supply complementary power to a long wavelength channel to which the state of the first band is related, in accordance with the at least one first pump light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a broadband WDM (wavelength division multiplexing) transmission system and a protection scheme against failures due to the absence of short wavelength signals for long wavelength channels in such systems.

  A related art optical communication system includes a transmission terminal for generating a WDM optical signal formed by wavelength division multiplexing of a plurality of optical signals having different wavelengths, and an optical transmission path for transmitting the WDM optical signal transmitted from the transmission terminal And a receiving terminal for receiving the transmitted WDM optical signal. The optical communication system includes one or a plurality of optical repeaters having a function of amplifying a WDM optical signal on an optical transmission line as necessary.

  In such an optical communication system, the waveform of each optical signal deteriorates due to the nonlinear optical effect in the optical transmission line. In order to suppress the deterioration of the waveform, it is effective to reduce the optical power of the optical signal applied to the transmission path. This optical power reduction is achieved by reducing the optical signal-to-noise ratio due to noise accumulation in the optical amplifier ( Cause an increase in OSNR).

  For this purpose, it has been proposed to use a combination of a discrete optical amplifier provided in a repeater and a distributed optical amplifier that commonly uses an optical transmission line as an optical amplification medium. In the discrete optical amplifier, the amplification medium and the pump light source are concentrated in one area. In contrast, the amplification medium of the distributed optical amplifier is disposed between two remote points, and the pump light source is provided at one or both of them.

  Fiber doped optical amplifiers are a class of optical fiber amplifiers. In doped fiber amplifiers, lanthanide rare earth elements are added to the optical fiber. The structure of the lanthanide rare earth atom at the electronic excitation level enables amplification by stimulated emission in the low absorption wavelength region of the optical fiber. Its operating bandwidth is limited to a certain wavelength range. That is, in the wavelength band of 1060 nm for neodymium (Nd), in the wavelength band of 1300 nm for praseodymium (Pr), in the wavelength band of 1450 nm for thulium (Tm), and in the wavelength band of 1550 nm for erbium (Er). Amplify each.

  Another class of optical fiber amplifiers is stimulated Raman scattering (SRS), which utilizes inelastic scattering processes between photons and lattice oscillating optical phonons. As will be described later with reference to FIG. 4, it has a wide gain width and a gain shift of 13.3 THz (about 100 nm). In contrast to erbium-doped fiber amplifiers, the SRS effect also occurs in ordinary optical fibers. Furthermore, the pumping wavelength can be set for any amplification wavelength.

  The low-loss transmission band of silica optical fiber covers a wavelength range of 1450 to 1650 nm, and at least around 1550 nm. Until recently, only erbium-doped fiber amplifiers (EDFA) covering the so-called C band (1530 to 1565 nm) and EDFA covering the so-called L band (1570 to 1605 nm) were used. In these systems, the distributed Raman amplification (DRA) pump wavelength is much shorter than the signal wavelength.

  Due to the demand for increased transmission capacity of optical fiber systems, it is desirable to extend the optical bandwidth in a single fiber. Band extension to longer wavelengths has several problems. In other words, the loss characteristics in this wavelength band vary widely between installed fibers, which makes system design more difficult and necessitates further development of materials and technologies for optical components (eg, photodiodes). . Raman amplification can be used in this wavelength band in principle. However, the pump wavelength partially overlaps the short wavelength signal in the C band.

  On the short wavelength side of 1530 nm or less, the low loss region of the silica fiber extends to 1450 nm. Although the Raman pump wavelength in this region does not overlap with the signal, those wavelength bands correspond to the water peak of the optical fiber, and the absorption loss there is large. However, due to the effectiveness of high performance pump lasers, Raman amplification is a technique that can be implemented in this wavelength band. Further, thulium-doped amplifiers and gain-shifted thulium-doped amplifiers are candidates for amplifiers for wavelengths below 1530 nm. The supplemental wavelength regions are referred to as the S + band (1450 to 1490 nm) and the S band (1490 to 1530 nm). In these new wide bandwidth systems, short wavelength signals serve as DRA pump light for long wavelength signals. S + and S-band wavelengths move optical power to C and L-band channels via SRS. Distributed Raman excitation of S + and S-band channels compensates for power reduction due to SRS and compensates for increased fiber loss at S + and S wavelengths. When operating at all wavelengths, the power transfer is balanced.

  The conventional optical communication system will be described in more detail with reference to the drawings.

  FIG. 1 shows a graph of a typical optical loss spectrum of a silica optical fiber where the low loss region covers a wavelength range of 1450 to 1650 nm. An optical amplifier can simultaneously amplify a group of wavelengths. The C and L bands correspond to the wavelength range of an erbium-doped fiber with erbium-doped and gain-shifted. The S + and S bands are related to the wavelength range of thulium-doped fibers doped with thulium and shifted in gain. When 1450 nm and 1550 nm light is transmitted 100 km over an optical fiber having a loss of 0.26 dB / km, they suffer a loss of 26 dB and 20 dB, respectively. Therefore, light having a wavelength of 1450 nm suffers about 0.06 dB / km more loss than the minimum loss wavelength.

  FIG. 2A shows a conventional WDM transmission system. The reference numerals of the optical elements in the drawings including FIG. 2A are defined in FIGS. 3A to 3F. FIG. 3A shows various types of optical amplifiers. The C and L bands can also be amplified separately with a wideband C / L band amplifier. Thus, the S and S + bands can be amplified by either individual doped fiber amplifiers or Raman amplifiers, or amplifiers covering the entire S + and S band wavelength range. This type of amplifier is indicated by a double triangle below. A variable optical attenuator (VOA) can be added to the amplifier as a means for adjusting the amplifier output.

  FIG. 3B shows an optical circulator, and FIG. 3C shows an optical tap. FIG. 3D shows an optical switch. 3E and 3F show a WDM coupler.

  Returning to FIG. 2A, the WDM transmission system comprises a transmitter, a transmission fiber connected to a remote location, a discrete optical amplifier and a receiver to compensate for the fiber loss. The transmission capacity is increased by multi-wavelength transmission. Optical amplifiers add noise in the form of amplified spontaneous emission, which reduces the optical signal-to-noise ratio and thus causes errors in signal detection. Distributed Raman amplification can improve the signal-to-noise ratio because it amplifies the signal along the transmission fiber. Also, SRS tilt (described later) can be compensated for in this system. There is a control scheme that allows adjustment of the spectral tilt based on changes in usage conditions of C and L band channels (OECC '99 by T. Hosida, T. Terahara, J. Kumasako and H. Onaka, “Two Band WDM Optical SNR degradation due to stimulated Raman scattering in transmission systems and its compensation by optical level management ").

  In general, the gain of distributed Raman amplification is not as high as that of a discrete amplifier. As shown in FIG. 2B, backward propagation amplification is used to average the bit pattern dependent amplification that causes power fluctuations. Commercial systems use C and L band amplifiers. The laboratory has demonstrated three-band (S, C, L) transmission as shown in FIG. Experimental study on the compensation ").

  In high-density WDM systems, channel interleaved bi-directional transmission as shown in FIG. 2D suppresses defects due to non-linear interaction (cross-phase modulation, four-wavelength mixing) between adjacent channels, thereby improving spectral efficiency. Become. In the amplification stage, the forward and reverse propagation channels are separated by an optical circulator (directional coupling element).

  FIG. 4 shows the optical power reduction due to stimulated Raman scattering as well as fiber loss. In a wideband WDM transmission system with a large number of channels, power transfer from many short wavelengths to long wavelengths occurs due to SRS. The Raman gain depends on the frequency shift between short and long wavelengths. It is maximum around 13.3 THz for silica fiber. Therefore, for distributed Raman excitation, it is most effective to assign a pump wavelength shifted to the short wavelength side of about 100 nm with respect to the signal wavelength. In wideband WDM systems, short wavelength signals provide an efficient pump light source for long wavelength channels.

  FIG. 5 shows SRS spectral tilt compensation using DRA and pre-emphasis (relay power level control). It is possible to compensate for large absorption losses as well as SRS power reduction using distributed Raman amplification and pre-enhancement of short wavelength channels. ("Experimental study on SRS loss and compensation in 3-band WDM transmission" by ECOC2000, Yutaka Yano, Tadashi Kasamatsu, Yoshitaka Yokoyama and Takashi Ono). Note that power transfer is balanced when all channels are on.

  However, in wideband systems, power transfer to C and L band signals is reduced by interrupting the operation of short wavelength channels (due to failure or for maintenance purposes) or by reducing the number of on-state short wavelength channels. Or disappear. As a result, the C and L band signal output power is reduced and the OSNR is deteriorated, so that these channels are prone to error.

  Accordingly, a general object of the present invention is to provide a long wavelength channel control system in a broadband WDM optical fiber transmission system that solves the above-mentioned problems.

  Another object of the present invention is to provide an optical amplifier device capable of protecting a long wavelength channel of a broadband optical fiber transmission system in which power transfer from a short wavelength to a long wavelength due to stimulated Raman scattering is indispensable for transmission of a long wavelength signal. It is to provide.

  Another object of the present invention is to provide an optical communication system using the above protection scheme.

  The above object of the present invention is an optical amplifier apparatus for use in a system that produces a power transfer from a relatively short wavelength signal to a relatively long wavelength signal, comprising: an amplifier stage connected to an optical transmission medium; A monitor for monitoring a state of one band, and at least one first pump light by supplying at least one first pump light to an optical transmission medium based on the state of the monitored first band Is achieved by an optical amplifier arrangement comprising a pump light source section that provides supplementary power to the long wavelength channel with which the first band is associated.

  The object of the present invention is also an optical amplifier apparatus for use in a bidirectional system for generating a power transfer from a relatively short wavelength signal to a relatively long wavelength signal, the first and second amplifier systems, It is also achieved by an optical amplifier device comprising a directional coupling element that couples the first and second amplifier stages to an optical transmission medium. Each of the first and second amplifier systems includes an amplification stage coupled to the optical transmission medium, a monitor for monitoring the state of the first band, and optical transmission based on the state of the monitored first band. A pump that provides at least one first pump light to the medium so that the at least one first pump light provides supplemental power to a long wavelength channel associated with a first band condition. It consists of a light source part.

  The above object of the present invention is also a method of controlling an optical amplifier apparatus used in a system that generates a power transfer from a relatively short wavelength signal to a relatively long wavelength signal, and monitors the state of the first band. Then, by supplying at least one first pump light to the optical transmission medium based on the monitored first band state, the first pump light becomes a long wavelength channel related to the first band state. This can also be achieved by a method of controlling the optical amplifier device comprising the steps of supplying supplementary power.

  The above object of the present invention is also achieved by an optical transmission system comprising an optical amplifier device and an optical transmission medium for coupling the optical amplifier devices. One of the optical amplifier devices includes an amplifier stage coupled to the optical transmission medium, a monitor for monitoring a state of the first band, and an optical transmission medium based on the monitored state of the first band. A pump light source unit for providing at least one first pump light so that the at least one first pump light provides supplementary power to a long wavelength channel associated with a first band condition. And more.

  The above object of the present invention is also achieved by a bidirectional optical transmission system that produces a power transfer from a relatively short wavelength signal to a relatively long wavelength signal. This bidirectional optical transmission system includes an optical amplifier device and an optical transmission medium that couples the optical amplification devices. One of the optical amplifying devices comprises a first and second amplifier system and a directional coupling element that couples the first and second amplifier stages to an optical transmission medium. Each of the first and second amplifier systems includes an amplification stage coupled to the optical transmission medium, a monitor for monitoring the state of the first band, and optical transmission based on the state of the monitored first band. A pump that provides at least one first pump light to the medium so that the at least one first pump light provides supplemental power to a long wavelength channel associated with a first band condition. It consists of a light source part.

  The features of the present invention and the functions and effects thereof will be further clarified by the following detailed description in conjunction with the accompanying drawings.

  First, the principle of the present invention will be described.

  According to one aspect of the invention, a plurality of additional Raman pump light sources are provided in a plurality of amplifier stages. These light sources are turned off when the S + and S bands are all on. The S + and S band power levels are monitored by a photodiode. Depending on the location of the photodiode, the control signal is used to switch on or off the substitute Raman pump laser at the same relay node or at one of the nodes before or after. The photodiode can be placed either in front of the amplifier or behind the amplifier. Therefore, even if the S + and S band channels are not fully operational, highly reliable C / L band transmission can be maintained.

  Referring to FIG. 6, in the case of full S +, S-band channel or partial channel lack, power transfer from short to long wavelength is reduced or completely interrupted. As a result, the power of the C and L band channels is reduced and the OSNR tends to increase the likelihood of error in these channels. Therefore, there is a need for a backup system and control mechanism for supplying optical pump power to the C and L band channels in the absence of the S +, S band or a partial lack thereof. Furthermore, the increase in C and L-band relay station output power of each amplifier stage can improve the system performance in the absence of the short wavelength band or a partial lack thereof.

  In particular, when the entire S + band is partially turned off or when the power level of the S + band is lowered, as shown in FIG. 6A, a long wavelength channel (long wavelength light or One or more substitute pump light switches of different wavelengths can be turned on so that power can be supplied to the long wavelength region. As described in conjunction with FIG. 4, in distributed Raman excitation, it is most effective to assign a pump wavelength shifted to the short wavelength side by about 100 nm with respect to the signal wavelength. Therefore, the substitute pump light pumps most efficiently to the wavelength channel located at a wavelength 100 nm longer than the wavelength of the substitute pump light. In this way, pump power can be supplied to the C and L bands.

  The number of substitute pump lights and the wavelength value thereof can be arbitrarily selected. In general, a longer wavelength channel can be pumped more efficiently by a larger number of substitute pump lights. The wavelength of the substitute pump light is desirably selected so as not to overlap with that of the S + band signal channel. This is important when the substitute pump light is switched on when the power level of the S + band is reduced (but not completely off). Some surrogate pump lights may have a wavelength that overlaps the S + band signal channel if the surrogate pump light is switched on only when the S + band is completely off.

  In FIG. 6 (a), two S + substitute pump lights are illustrated. Alternatively, a single S + substitute pump light or three or more S + substitute pump lights can be used.

  When the S band is completely or partially turned off or when the power level of the S band is lowered, power is supplied to a channel having a longer wavelength as shown in FIG. 6B. It is possible to switch on one or more substitute pump lights of different wavelengths so that they can. The wavelength of the substitute pump light shown in FIG. 6 (b) is longer than that of the substitute pump light shown in FIG. 6 (a).

  If both S + and S bands are wholly or partly turned off, or if the power levels of both bands are reduced, as shown in FIG. And the substitute pump shown in part (b) is switched on.

  When a part of the short wavelength band is in the OFF state, as shown in part (d) of FIG. 6, the part can be substituted with a single substitute pump wavelength. That is, channel-by-channel control can be achieved.

  Thus, according to the present invention, the substitute pump light is supplied when the power transfer from the short wavelength to the long wavelength due to stimulated Raman scattering is not sufficient for the transmission of the long wavelength channel. Therefore, even if the power transfer to a long wavelength such as the C and L bands is reduced or eliminated due to a decrease in the number of effective short wavelength channels, the wavelength in the short wavelength band such as the S + and / or S band is eliminated. Alternative pump light can be provided so that the reduction or lack of its power transfer can be compensated. The number of substitute pump lights or the power level thereof can be adjusted based on the power level of a long wavelength band such as the C and L bands.

  FIG. 7A is a block diagram of a WDM transmission system according to a first embodiment of the present invention. The optical repeater nodes 10 and 20 configured to include an amplifier device are coupled by an optical fiber 14 which is one optical transmission medium. The amplifier device 10 includes an amplifier stage 11, a central processing unit (CPU) 12 and an electrically erasable programmable read only memory (EEPROM) 13. Similarly, the relay node 20 includes an amplifier stage 16, a CPU 17 and an EEPROM 18. Amplifier stages 11 and 16 are coupled by optical fiber 14. The signal light and the pump light are propagated through the optical fiber 14. The CPUs 12 and 17 exchange control information through the optical monitoring channel 15 that is also transmitted through the optical fiber 14.

  FIG. 8 is a block diagram of a configuration example of the relay station node 10. The part symbols are defined in FIGS. 3A to 3F. The amplifier stage 11 includes WDM couplers 31 and 32, a C / L optical amplifier stage 33, optical taps 34 and 35, photodiodes (PD) 36 and 37, optical amplifiers 38 and 39, and WDM optical couplers 40 and 41. The optical circulator 43 is provided in the optical transmission line 14. A Raman pump light source unit (LD) 42 controlled by the CPU 12 is coupled to the optical circulator 43. The Raman pump light source unit 42 is provided in front of the WDM coupler 31. The Raman pump light emitted by the Raman pump light source unit 42 is propagated in the opposite direction to the signal light.

  The WDM coupler 31 separates the multiplexed signal light into C and L bands (C / L signals) and S + and S bands (S + / S signals). The amplifier stage 33 amplifies the C / L signal. The relay station output power of the amplifier stage 33 can be adjusted by the CPU 12. The WDM coupler 32 separates the S + / S signal into an S + signal and an S signal. The amplifier 38 amplifies the S signal. The amplifier 39 amplifies the S + signal. The monitoring photodiode 36 monitors the state (level) of the entire S band by referring to a part of the S signal via the optical tap 34. The monitor 37 refers to a part of the S + signal via the optical tap 35 and monitors the state (level) of the entire S + band. The CPU 12 can adjust the relay station output power of the amplifiers 38 and 39. The WDM coupler 40 multiplexes the amplified S and S + signals to generate a multiplexed S + / S signal. The WDM coupler 41 multiplexes the amplified C / L signal and the S + / S signal to generate a multiplexed signal, and this signal is transmitted through the optical fiber 14.

  The Raman pump light source unit 42 is configured as shown in FIG. The Raman pump light source unit 42 includes a coupling unit 45, an S + Raman pump light source unit 46, an S Raman pump light source unit 47, an S + signal substitute (supplementary) Raman pump light source unit 48, and an S signal substitute Raman pump light source unit 49. Become. The S + Raman pump light source unit 46 generates S + band pumping light of wavelengths λ1 and λ2 that pumps the S + band (see FIG. 5). The light source unit 46 includes a laser diode LD that emits λ1 pump light and another laser diode LD that emits λ2 pump light. These laser diodes are controlled by the CPU 12 via a digital-to-analog (D / A) converter. The level of the pumping light is monitored by a photodiode through an optical tap and is supplied to the CPU 12 through an analog / digital (A / D) converter.

  The S Raman pump light source unit 47 emits S band pumping light of wavelengths λ3 and λ4 that pumps the S band (see FIG. 5). The light source unit 47 has the same structure as the light source unit 46.

  The S + and S signal substitute Raman pump light source portions 48 and 49 are newly provided according to the first embodiment of the present invention. The light source unit 48 generates two substitute pump lights of wavelengths λ5 and λ6 in a region between the S-band Raman pump wavelength and the S-band signal wavelength. The light source unit 48 has the same structure as the light source units 46 and 47. The light source unit 49 generates two substitute pump lights of wavelengths λ7 and λ8 in a region between the S band Raman pump wavelength and the S band signal wavelength. The light source unit 49 has the same structure as the light source units 46 to 48.

  The coupler 45 includes seven WDM couplers and multiplexes eight Raman pump lights from λ1 to λ8. The multiplexed Raman pump light is added to the circulation unit 43, and thereby propagates in the direction opposite to the direction in which the signal light is propagated on the optical fiber 14 (reverse propagation). That is, the multiplexed pump light generated in this way is applied to a signal coming from a preceding relay node (not shown in FIG. 9). The circulator 43 can couple the multiplexed Raman pump light to the optical fiber 14 even if it is spectrally overlapping with the S + / S signal wavelength.

  The CPU 12 controls the pump light source units 46 to 49 according to the levels of the S + and S bands monitored by the photodiodes 36 and 37, respectively. Output signals of the photodiodes 36 and 37 are supplied to the CPU 12 via the A / D converters 51 and 52. As will be described later, the CPU 12 obtains information on the state of the amplifier and controls them. The EEPROM 13 stores a program executed by the CPU 12, and preset parameter values of the gain of the amplifier (or an attenuator after the amplifier) and the level of the pump light source. When the system is installed, parameter settings of Raman pump power and output power of C and L band channels for various scenes (S + band off, S band off, etc.) are determined.

  FIG. 10A shows a flowchart of the control operation executed by the CPU 12. FIG. 10B shows a table showing the possible state changes of the S + and S bands. As shown in FIG. 10B, 16 state changes of the S + and S bands can occur. Each state change is identified by serial number #i. For example, there is no state change when # i = 1. When # i = 4, both the S + and S bands change from on to off. When # i = 7, the S + band changes from on (signal light present) to off (no signal light), and the S band changes from off to on. In accordance with this control sequence, the CPU 12 switches on or off the Raman pump light source sections 48 and 49 when a change in state of the S + and S bands occurs.

  In FIG. 10A, the CPU 12 reads S + and S-band monitoring signals supplied from the photodiodes 36 and 37 via the A / D converters 51 and 52 (step S11). Thereafter, the CPU 12 determines whether there is a change in the state of the S + and S bands. When # i = 1, 6, 11 and 16, there is no change. In that case, the process proceeds to step S18 described later in the control sequence. On the other hand, when the state change of the S + and S bands occurs, the CPU 12 turns off the switch of the discrete amplifier of the band changed from on to off (step S13). Thereafter, the CPU 12 turns off the switch of the substitute Raman pump in the band changed from off to on (step S14). When # i = 7, the CPU 12 switches off the amplifier 39 of FIG. 8 and switches off the S signal substitute Raman pump light source unit 49. In step S13, depending on the optimum condition determined at the time of system installation, the Raman pump in the band changed from on to off may also be switched off.

  Thereafter, the CPU 12 transmits, via the control channel 15, a control signal for adjusting the powers of the C and L bands in accordance with the preset value of the parameter for the case of #i stored in the EEPROM 13 to the preceding relay station node ( Step S15). If necessary, the process of step S15 can be omitted. The power in the C and L bands can be adjusted by controlling an optical amplifier or an attenuator downstream of the amplifier.

  Thereafter, the CPU 12 switches on the substitute Raman pump of the band changed from on to off (step S16), and switches on the discrete amplifier of the band changed from off to on (step S17). When # i = 7, the CPU 12 switches on the S + signal substitution Raman pump light source 48 shown in FIG. 8 and switches on the optical amplifier 38.

  Finally, the CPU 12 receives a control signal from the relay station node at the next stage, and adjusts its own C and L band amplifiers accordingly (step S18). That is, the amplifier stage 33 of the relay node 10 shown in FIG. 8 is adjusted by the control signal sent from the relay node 20 shown in FIG. Regardless of the state change, the C and L band amplifiers (or the subsequent attenuator) are adjusted by the control signal received from the relay node at the next stage.

  The relay station node 20 shown in FIG. 7 operates in the same manner as the relay node 10, and thus the description thereof is omitted.

  A second embodiment of the present invention will be described below.

  FIG. 11 is a block diagram of a WDM transmission system according to a second embodiment of the present invention. In FIG. 11, the same components as those in FIG. The two relay station nodes 100 and 200 use an optical spectrum analyzer (OSA) to monitor the S + and S bands. The advantage of the photodiodes for monitoring the S + and S bands in the first embodiment of the present invention is that their response is much faster than the optical spectrum analyzer. On the other hand, as will be described later, more precise control can be realized by using a spectrum analyzer.

  The relay node 100 is provided with optical spectrum analyzers (OSA) 20 and 22 coupled to the optical fiber 14 via optical taps 19 and 21, respectively. The optical spectrum analyzer 20 monitors the optical spectrum of the entire band on the input side of the amplifier stage 11 and supplies the spectrum data to the CPU 12. The optical spectrum analyzer 22 monitors the optical spectrum of the entire band on the output side of the amplifier stage 11 and supplies the spectrum data to the CPU 12. The amplifier stage 11 and the Raman pump light source unit 42 are configured as shown in FIG. 8, for example.

  Similarly, repeater node 200 includes optical spectrum analyzers 24 and 26 coupled to the input and output sides of the amplifier via optical taps 23 and 25, respectively. FIG. 12A shows a flowchart of the control operation of the CPU 12 of the relay station node 100. FIG. 12B shows a table showing possible state changes of the S + and S bands. The contents of the table of FIG. 12B are the same as the contents of the table of FIG. 10B. The control sequence in FIG. 12A includes steps S12 to S18 described with reference to FIG. 10A, and further includes specific steps S20 and S21 resulting from the use of the optical spectrum analyzer. In steps S12 to S18, the spectral data is used instead of the photodiode monitoring output.

  The CPU 12 first executes step S20. In step S <b> 20, the CPU 12 reads input and output spectrum data from the optical spectrum analyzers 20 and 22. Further, the CPU 12 receives the span input spectrum data from the preceding relay station node (relay station node 200), and supplies the spectrum data of the relay station node 100 to the subsequent relay node. Thereafter, the CPU 12 executes Step S12. In the case of # i = 1, 6, 11 or 16, the CPU 12 adjusts its pump power by controlling the laser diode of the operating pumping power light source unit in the light source units 46 to 49 by the corresponding D / A converter. This adjustment is made with reference to the input and output spectrum data and the input spectrum data received from the preceding relay node. Input and output spectral data indicate the status of all channels in each of the bands. Therefore, it is possible to set the predetermined preset level stored in the EEPROM 13 by precisely adjusting the pumping force. Further, in step S21, the CPU 12 transmits a control signal to the preceding relay node for adjusting the signal input power. Thereafter, the CPU 12 executes Step S18 following Step S20.

  These first and second embodiments of the present invention can be modified so that three or more Raman pumping lights can be used. These Raman pump light sources may be multi-wavelength pump light sources as disclosed in, for example, WO00 / 5622. The monitoring photodiodes 36 and 37 used in the first embodiment of the present invention monitor all S + and S bands, respectively. Instead, a set of monitoring photodiodes may be combined with a WDM coupler to simultaneously monitor multiple wavelength groups (ie, subbands) within the band. A monitoring photodiode may also be provided after the amplifier.

  Next, another embodiment of the present invention will be described.

  FIG. 13A is a block diagram of a relay station node 10C according to the third embodiment of the present invention. This relay station node 10C is different from the relay station node 10 with respect to the position of the optical circulator 43. When the coupling loss of the WDM coupler 31 is sufficiently low at a short Raman pump wavelength, the optical coupler 43 can be disposed behind the WDM coupler 31 as shown in FIG. 13A. This configuration has an effect that the loss is reduced with respect to the C- and L-band signal lights in the transmission path.

  FIG. 13B is a block diagram of a modification of the relay node 10C. The relay node 10D shown in FIG. 13B is configured such that the C / L signal light propagates in the opposite direction to the S + / S signal light. That is, the S + / S Raman pump light emitted by the Raman pump light source unit 42 is propagated in the same direction as the C / L signal light.

  FIG. 13C is a block diagram of another modification 10E of the relay node 10C. The Raman pump used in the light source unit 42 described in the embodiment of the present invention is separated into two light source units 42a and 42b. The light source unit 42a corresponds to a combination of S + and S Raman pump light source units 46 and 47 and related WDM couplers shown in FIG. The light source unit 42b corresponds to a combination of S + and S signal substitute Raman pump light source units 48 and 49 and related WDM couplers shown in FIG. The S + / S Raman pump light source unit 42 a is coupled to the optical fiber 14 in front of the WDM coupler 31 by a WDM coupler 55. The S + and S signal substitution Raman pump light source unit 42 b is coupled to a corresponding internal optical fiber via an optical circulator 43 so as to be located behind the WDM coupler 31. In this configuration, the coupling loss related to the S + / S Raman pump light is reduced compared to the relay node 13A.

  A modification of the relay node 10E is illustrated as a relay node 10F shown in FIG. 13D. The C / L signal light propagates in the same direction as the Raman pump light and propagates in the opposite direction to the S + / S signal light.

  FIG. 14A is a block diagram of a relay node 10G according to the fourth embodiment of the present invention. The S signal substitute Raman pump light source unit 49 is coupled to a corresponding internal S signal transmission path so as to be located behind the WDM coupler 32. The monitoring photodiode 36 monitors a part of the S signal obtained from the optical tap 34. The light source unit 49 is controlled based on the state of the S band. The S + signal substitution Raman pump light source unit 48 is coupled to a corresponding internal S + signal transmission path so as to be positioned behind the WDM coupler 32. The monitoring photodiode 37 monitors a part of the S + signal obtained from the optical tap 35. The light source unit 48 is controlled based on the state of the S + band.

  FIG. 14B is a block diagram of a modification 10H of the relay node 10G. The C / L signal light propagates in the same direction as the Raman pump light and propagates in the opposite direction to the S + / S signal light.

  FIG. 15A is a block diagram of an optical repeater node 10I according to the fifth embodiment of the present invention. Here, the wavelength of the signal extends only for the S band. In this case, the Raman pump wavelength can be assigned without spectrally overlapping the signal wavelength. As a result, it is possible to use a WDM device to couple S + and S signal substitution Raman pumps to the transmission line. The integrated S Raman pump light / S + and the S signal substitute Raman pump light source unit 42 c are coupled to the optical fiber 14 by a WDM coupler 55 disposed in front of the WDM coupler 31. The Raman pump light emitted from the light source unit 42c propagates in the opposite direction to the S / C / L signal light. The light source unit 42c includes Raman pump light source units 47, 48 and 49 of the coupling unit 45 shown in FIG. 9 and an associated WDM coupler. The S band is monitored by a monitoring photodiode 37 coupled to an internal S signal transmission line extending from the WDM coupler 31.

  The Raman pump light source unit 42 c is controlled by the state of the S band monitored by the S signal monitor 37 under the control of the CPU 12. For example, the Raman pump light source unit 48 is maintained in an on state, and the Raman pump light source unit 49 is switched on / off based on the state of the S band. Instead, the S + and S signal substitute light source units 48 and 49 may be simultaneously switched on / off based on the state of the S band.

  FIG. 15B is a block diagram of a modification 10J of the relay station node 10I. S-band Raman pump light propagates in the same direction. The Raman pump light source unit 42 is separated into an S Raman pump light source unit 47 and an S + and S signal substitute Raman pump light source unit 42b. The light source unit 42 b is coupled to the optical fiber 14 constituting the transmission path by a WDM coupler 60 positioned in front of the WDM coupler 41. The S + and S signal substitute Raman pump light propagates in the opposite direction to the C / L signal light. The S pump light propagates in the same direction as the C / L signal light. The S + and S signal substitution Raman pump light source 42 b is controlled by the state of the S band monitored by the monitoring photodiode 37.

  FIG. 16A is a block diagram of an optical repeater node 10K according to another modification of the repeater node 10I. The WDM coupler 61 is provided behind the WDM coupler 31. The S + and S signal substitute Raman pump light source 42b is coupled to an internal S signal transmission path by a WDM coupler 61. The S Raman pump light and the S + / S signal substitute Raman pump light are propagated in the opposite direction to the S / C / L signal light.

  FIG. 16B is a block diagram of a modification 10L of the relay station node 10K. A WDM coupler 61 to which the S + and S signal substitution Raman pump light source 42 is coupled is provided in the subsequent stage of the S frequency band amplifier 38. The S + and S signal substitute Raman pump light propagates in the opposite direction to the C / L signal light. The S Raman pump light propagates in the same direction as the C / L signal light.

  FIG. 17A is a block diagram of an optical repeater node 17A according to the sixth embodiment of the present invention. In this embodiment, a pair of optical switches 65 and 66 are used to implement C / L band transmission protection when S + and / or S band transmission is interrupted. Optical switches 65 and 66 are coupled to internal transmission lines by WDM couplers 75 and 76, respectively. Each of the optical switches 65 and 66 allows selection between two optical paths. The pair of optical switches 65 and 66 is provided in front of the WDM coupler 31, and selectively connects either the S + / S Raman pump light source unit 42a or the S + and S signal substitute Raman pump light source unit 42b to the transmission line. To do.

  The optical switches 65 and 66 are controlled by the CPU 12 together with the S + and S signal substitute Raman pump light source 42b as shown in FIG. The monitor output state is supplied from the preceding relay node. Switching control of the optical switches 65 and 66 is performed in the same manner as the on / off control of the Raman pump light source unit described above. That is, the optical switches 65 and 66 are operated according to the table shown in FIG. 10B.

  The optical switches 65 and 66 do not allow simultaneous transmission of S + and S signal substitute Raman pump light and S + / S signal light. Therefore, it is required to perform switching between the S + / S Raman pump light and the S + and S signal substitute Raman pump light. This means that only the entire S + and S bands can be substituted. The Raman pump light is propagated in the opposite direction to the signal light.

  An S + / S amplifier stage 62 is used to amplify S + and S-band signal light. The monitoring photodiode 63 monitors the state of the S + and S bands. The monitor output for controlling the S + and S signal substitute Raman pump light source unit of the next-stage relay station node is transmitted to the next-stage relay station node. The S + / S / C / L signal light is propagated in the same direction.

  FIG. 17B is a block diagram of a modification 10N of the optical repeater node 10M. A pair of optical switches 67 and 68 are provided in front of the WDM coupler 41. The S + and S signal substitution Raman pump light source unit 42b is selectively coupled to the optical fiber 14 by switches 67 and 68 controlled by the CPU 12. The C / L signal light propagates in the opposite direction to the S + / S signal light and propagates in the same direction as the S + / S Raman pump light. The S + and S signal substitute Raman pump light propagates in the opposite direction to the C / L signal light. In order to control the switches 67 and 68 and the S + and S signal substitute Raman pump light source section 42b, the monitor output of the photodiode 63 provided in the subsequent stage of the S + / S amplifier stage 62 is used by the CPU 12.

  FIG. 18A is a block diagram of an optical repeater node 10P according to the seventh embodiment of the present invention. An optical switch 69 for selectively coupling the S + and S signal substitute Raman pump light source 42 b to the transmission line is provided behind the WDM coupler 31. The optical switch 69 is switched on / off according to the state of the S + and S bands monitored by the monitoring photodiode 63 under the control of the CPU 12. The S + / S Raman pump light source 42 a is provided in front of the WDM coupler 31 and is coupled to the optical fiber by the WDM coupler 55. The S + / S / C / L signal light propagates in the same direction, and the S + / S Raman pump light and the S + / S signal substitute Raman pump light propagate in the opposite direction to the signal light. The CPU 12 controls the S + and S signal substitution Raman pump light source unit 42 b and the optical switch 69 based on the state of the S + / S band monitored by the photodiode 63.

  FIG. 18B is a block diagram of Modification 10Q of relay station node 10P. Like the relay node shown in FIG. 18A, the optical switch 70 is provided behind the WDM element 31, but is provided at a different position. The S + and S signal substitute Raman pump light source unit 42b is selectively coupled to the WDM coupler 41 by the switch 70 based on the state of the S + / S band under the control of the CPU 12. The S + and S signal substitute Raman pump light switched based on the state of the S + / S band is propagated in the opposite direction to the C / L signal light and the S + / S Raman pump light.

  FIG. 19A is a block diagram of an optical repeater node 10R according to an eighth embodiment of the present invention. The Raman pump light source 48 is coupled behind the WDM coupler 56 by an optical switch 72 for the purpose of substituting S + signal light. The Raman pump light source 49 is coupled behind the WDM coupler 56 by an optical switch 71 for the purpose of substituting S signal light. The CPU 12 controls the Raman pump light source unit 48 and the switch 72 based on the state of the S + band monitored by the photodiode 37. Similarly, the CPU 12 controls the Raman pump light source unit 49 and the switch 71 based on the state of the S band monitored by the photodiode 36. The S + / S Raman pump light source unit 42 a is coupled to the optical fiber 14 by a WDM coupler 55. The S + / S Raman pump light and the / S + and S signal substitute Raman pump light propagate in the same direction as the S + / S / C / L signal light, and propagate in the opposite direction.

  FIG. 19B is a block diagram of a modification 10S of the optical amplifier 10R. The optical switches 73 and 74 are provided in the subsequent stage of the optical amplifiers 38 and 39, respectively. The optical switch 73 selectively couples the WDM coupler 40 and the Raman pump light source 49 under the control of the CPU 12 based on the state of the S band. Similarly, the optical switch 74 selectively couples the WDM coupler 40 and the Raman pump light source 48 based on the state of the S + band under the control of the CPU 12. The S + and S signal substitute Raman pump light propagates in the opposite direction to the C / L signal light and the S + / S Raman pump light source unit 42a.

  FIG. 25A shows an optical device for monitoring a portion of the forward and backward propagating light of the bidirectional transmission system S + S / CL by using an optical spectrum analyzer. Forward propagating light is in the S + and S bands and backward propagating light is in the C and L bands. The optical taps 160 and 161 are provided before and after the amplifier stage. The WDM coupler 162 couples a portion of the input signal to the amplifier stage. The WDM coupler 163 combines a part of output signals. An optical spectrum analyzer (OSA) 164 connected to the WDM coupler 162 monitors the power level of the input signal. An optical spectrum analyzer (OSA) 165 connected to the WDM coupler 163 monitors the power level of the output signal. The optical spectrum analyzers 164 and 165 communicate with the CPU 12.

  The optical repeater node according to the ninth embodiment of the present invention will be described below. This relay node is used in the DWDM system as shown in FIG. 2D. In DWDM systems, channel interleaved bi-directional transmission can reduce disturbances due to non-linear interactions between adjacent channels. Channel interleaving is illustrated in the graph in FIG. 2D. Opposite (forward and backward) direction propagation channels indicated by solid and dashed lines, respectively, are interleaved. In the amplifier stage, an optical circulator is used to separate forward and backward propagating light. The amplifier structure for each direction is the same as that in the first to eighth embodiments of the present invention described above. The difference from these is that all the light in one branch propagates in the same direction.

  FIG. 20A is a block diagram of an optical repeater node 100A according to a ninth embodiment of the present invention that can be applied to a channel interleaved bidirectional S / C / L transmission system. The relay node 100A processes three bands S, C, and L. The relay station node 100A is coupled to an optical transmission line composed of the optical fiber 14 via the optical circulators 43 and 121, and constitutes two amplifier systems. One of these two systems includes the first optical amplifier involved in forward propagation and is composed of the aforementioned components. Similarly, the other system includes a second optical amplifier having the same structure as the first optical amplifier. This second amplifier involved in the back propagation includes a WDM coupler 122, a C / L amplifier stage 123, an S-band amplifier 124, an optical tap 125, a monitoring photodiode 126, an S + and S signal substitute Raman pump light source 127, and a WDM. A coupler 129, an S-band Raman pump light source unit 130, and a WDM coupler 131 are included.

  The multiplexed light passes through the circulator 43 and is added to the WDM coupler 31. The C / L signal light is added to the C / L amplifier stage 33. The S signal and S band pump light are applied to the S band amplifier 38. The S + and S signal substitute Raman pump light source unit 42 b is controlled by the CPU 12 based on the state of the S band in the forward propagation monitored by the photodiode 37 through the optical tap 34. The S + and S signal substitute Raman pump light is multiplexed by the WDM coupler 60 and the WDM coupler 41 with the amplified S band signal light and C / L signal light. Further, the S Raman pump light is coupled to the output of the WDM coupler 41 by the WDM coupler 55. Thereafter, the multiplexed light is transmitted to the optical fiber 14 by the circulator 121.

  Similarly, the multiplexed light passes through the circulator 121 and is added to the WDM coupler 122. If C / L signal light and S + / S signal substitute Raman pump light are present, they are added to the C / L amplifier stage 123. The S signal and S band pump light are applied to the S frequency band amplifier 124. The S + and S signal substitute Raman pump light source unit 127 is controlled by the CPU 12 based on the state of the S band in the backward propagation monitored by the photodiode 126 through the optical tap 125. The S + and S signal substitute Raman pump light is multiplexed by the WDM coupler 128 and the WDM coupler 129 with the amplified S band signal light and C / L signal light. Further, the S Raman pump light is coupled to the output of the WDM coupler 129 by the WDM coupler 131. Thereafter, the multiplexed light is transmitted to the optical fiber 14 by the circulator 43.

  FIG. 20B is a block diagram of a variation 100B of the optical repeater node 100A shown in FIG. 20A. The S Raman pump light / S + and the S signal substitute Raman pump light source unit 42 c are provided behind the WDM coupler 41 via the WDM coupler 55. The CPU 12 controls the light source unit 42 c based on the state of the S band monitored by the monitoring photodiode 37 coupled to the internal S band forward transmission line extending from the S band amplifier 38 via the WDM coupler 34. Similarly, an integrated S Raman pump / S + and an S signal substitute Raman pump light source unit 130 a are provided behind the WDM coupler 129 via the WDM coupler 131. The CPU 12 controls the light source unit 130 a based on the state of the S band monitored by the monitoring photodiode 126 coupled to the internal S band rear transmission line extending from the S band amplifier 124.

  FIG. 21 is a block diagram of an optical repeater node 100C according to the tenth embodiment of the present invention. This apparatus 100C is applicable to a channel interleaved bidirectional transmission system having S + / S / C / L bands. The forward amplifier system includes the WDM coupler 31, the C / L amplifier stage 33, the S + / S amplifier stage 62, the WDM coupler 41, the optical tap 69, the S + / S band monitoring photodiode 63, and the S + / S Raman pump light source unit. 42a, WDM coupler 55, S + and S signal substitute Raman pump light source section 42b, WDM coupler 76, and optical switches 67 and 68. Similarly, the backward amplifier system includes the WDM coupler 122, the C / L amplifier stage 123, the S + / S amplifier stage 134, the WDM coupler 129, the optical tap 135, the S + / S band monitoring photodiode 136, and the S + / S Raman. A pump light source unit 138, a WDM coupler 131, an S + and S signal substitute Raman pump light source unit 137, a WDM coupler 132, and optical switches 139 and 140 are included.

  The switches 67 and 68 and the Raman pump light source units 42 a and 42 b are controlled by the CPU 12 based on the state of the S + / S band in the forward propagation monitored by the photodiode 63. Similarly, the switches 139 and 140 and the Raman pump light source units 137 and 138 are controlled by the CPU 12 based on the state of the S + / S band in the backward propagation monitored by the photodiode 136. When the front S + and / or S band is not functioning, the S + and S signal substitute Raman pump light source unit 42 is selected by the optical switches 67 and 68. Similarly, when the rear S + and / or S band is not functioning, the S + and S signal substitute Raman pump light source unit 137 is selected by the optical switches 139 and 140.

  FIG. 22 is a block diagram of an optical repeater node 100D according to the eleventh embodiment of the present invention. The first (front) amplifier system includes a WDM coupler 31, a C / L amplifier stage 33, an S + / S amplifier stage 62, an optical tap 64, a monitoring photodiode 63, an S + and S signal substitute Raman pump light source unit 42b, The switch 70, the WDM coupler 41, the S + / S Raman pump light source unit 42a, and the WDM coupler 55 are included. The S + and S signal substitute Raman pump light source unit 42 b controlled based on the state of the S + / S band monitored by the photodiode 63 is selectively coupled to the WDM coupler 41 by the optical switch 70. The optical switch 70 is controlled by the CPU 12 and selects the S + and S signal substitute Raman pump light source unit 42b for protection of C / L band transmission in forward propagation. The S + / S Raman pump light source unit 42 a is coupled to the circulator 121 via the WDM coupler 55.

  The second (rear) amplifier system comprises a WDM coupler 122, a C / L amplifier stage 123, an S + / S amplifier stage 134, an optical tap 135, a monitoring photodiode 136, an S + and S signal substitute Raman pump light source 137, an optical The switch 140 includes a WDM coupler 129, a WDM coupler 131, and an S + / S Raman pump light source unit 138. The S + and S signal substitution Raman pump light source unit 137 controlled based on the state of the S + / S band monitored by the photodiode 136 is selectively coupled to the WDM coupler 129 by the optical switch 140. The optical switch 140 is controlled by the CPU 12 and selects the S + and S signal substitute Raman pump light source unit 137 for protection of C / L band transmission in backward propagation. The S + / S Raman pump light source unit 138 is coupled to the circulator 43 through the WDM coupler 131.

  FIG. 23 is a block diagram of an optical repeater node 100E according to the twelfth embodiment of the present invention. Except for the point related to the position where the S + / S Raman pump light source section 42a of the WDM coupler 55 is connected, the first (front) amplifier system is configured as shown in FIG. The WDM coupler 55 of the relay station node 100E is connected to the output of the WDM coupler 41. The second (rear) amplifier system has the same structure as the first amplifier system. In particular, the second amplifier system includes a WDM coupler 122, a C / L amplifier stage 123, a WDM coupler 1340, a WDM coupler 1290, a monitoring photodiode 140, an S-band amplifier 141, an optical tap 142, and an S signal substitute Raman pump light source unit. 143, an optical switch 144, a monitoring photodiode 145, an S + band amplifier 146, an optical tap 147, an S + signal substitution Raman pump light source 148, an optical coupler 149, an S + / S Raman pump light source unit 138, and a WDM coupler 129.

  When the S band is not functioning, the CPU 12 controls the optical switch 144 to select the Raman pump light source unit 143 instead of the S amplifier 141. When the S + band is not functioning, the CPU 12 controls the optical switch 149 to select the S + signal substitution Raman pump light source 148 instead of the S + amplifier 146.

  FIG. 24 is a block diagram of a modification of any of the optical amplifier devices 100 and 100B to 100E. If the Raman pump light does not spectrally overlap the signal wavelength, the associated Raman pump light source can be provided outside between the optical circulators 43 and 121 in which the two amplifier stages 150 and 151 are configured. A Raman pump light source unit 152 that emits Raman pump light that does not spectrally overlap with the signal wavelength is coupled to the optical transmission line via the WDM coupler 153. Similarly, a Raman pump light source unit 154 that emits Raman pump light that does not spectrally overlap with the signal wavelength is coupled to the optical transmission line via the WDM coupler 155.

  In the optical repeater node 100 and 100B to 100E, a monitoring photodiode is used, but here, an optical spectrum analyzer may be used instead.

  FIG. 25B shows an optical device for monitoring a portion of forward and backward propagating light in a channel interleaved bidirectional transmission system using an optical spectrum analyzer. The forward propagation light is included in the even channel and the backward propagation light is included in the odd channel. Here, instead of the WDM couplers 162 and 163, optical switches 166 and 167 are used as shown in FIG. 25B.

  The present invention is not limited to the configurations of the first to twelfth embodiments and modifications described above.

  For example, a different number of Raman pumping lights may be used. The Raman pump source may be a multi-wavelength pump source as disclosed in, for example, WO00 / 05622. Further, a pump light source capable of adjusting the wavelength may be used. A single photodiode can be used to monitor the entire optical band, or a set of photodiodes can be combined with a WDM coupler to simultaneously combine multiple wavelength groups (ie, subbands) in the band. It is also possible to monitor. The monitoring photodiode may be provided after the amplifier.

  The present invention also includes systems having other combinations of co-directional and counter-propagating signals and pump light, such as systems in which S + / S pump light is propagated in the same direction as the signal light. The present invention is not limited to a system using the S + / C / L band, but also includes a system using a combination of bands different from the above, such as a system including a wavelength region exceeding the L band (that is, the L + band).

  It is to be noted that the present invention provides a system that can be upgraded during operation of a wideband WDM system that causes power transfer from a relatively short wavelength channel to a relatively long wavelength channel for reliable long wavelength channel transmission. Is. If a short number of short wavelength channels are initially used in such a system and the addition of additional short wavelength channels is an option, it will be necessary to provide provisions to enable upgrades later in service. . For this purpose, power is supplied to a relatively long wavelength channel by a small number of short wavelength substitution Raman pumps. Here, each substitute pump wavelength replaces the short wavelength channel group to be installed later.

It is a graph which shows the typical fiber loss in a 1450-1600nm wavelength range of a silica single mode fiber. It is a block diagram of the conventional optical communication system. It is a block diagram of the conventional optical communication system. It is a block diagram of the conventional optical communication system. It is a block diagram of the conventional optical communication system. It is an optical component symbol explanatory drawing. It is an optical component symbol explanatory drawing. It is an optical component symbol explanatory drawing. It is an optical component symbol explanatory drawing. It is an optical component symbol explanatory drawing. It is an optical component symbol explanatory drawing. It is a figure which shows the optical power reduction by SRS and fiber loss. FIG. 6 shows SRS spectral tilt compensation using DRA and pre-enhancement. It is a figure which shows the principle of this invention. 1 is a block diagram of an optical transmission system according to a first embodiment of the present invention. FIG. 8 is a block diagram of an optical repeater node composed of an amplifier device used in the optical transmission system shown in FIG. 7. It is a block diagram of the Raman pump light source part shown by FIG. FIG. 10 is a diagram showing a control operation of the CPU shown in FIG. 9. FIG. 10 is a diagram showing a control operation of the CPU shown in FIG. 9. It is a block diagram of the optical transmission system by 2nd Example of this invention. FIG. 12 is a diagram showing a control operation of the CPU shown in FIG. 11. FIG. 12 is a diagram showing a control operation of the CPU shown in FIG. 11. It is a block diagram of an optical repeater node according to a third embodiment of the present invention. It is a figure which shows the modification of the optical repeater node shown by FIG. 13A. It is a figure which shows the modification of the optical repeater node shown by FIG. 13A. It is a figure which shows the modification of the optical repeater node shown by FIG. 13A. It is a block diagram of the optical repeater node by 4th Example of this invention. FIG. 14B is a block diagram of a variation of the relay station node shown in FIG. 14A. It is a block diagram of the optical repeater node by 5th Example of this invention. FIG. 15B is a block diagram of a modification of the relay node shown in FIG. 15A. FIG. 15B is a block diagram of another modification of the relay node shown in FIG. 15A. It is a block diagram of the modification of an optical repeater node. It is a block diagram of the optical repeater node by 6th Example of this invention. It is a block diagram of the modification of the relay node shown by FIG. 17A. It is a block diagram of the optical repeater node by 7th Example of this invention. FIG. 18B is a block diagram of a modification of the relay station node shown in FIG. 18A. It is a block diagram of the optical repeater node by 8th Example of this invention. FIG. 19B is a block diagram of a modification of the relay station node shown in FIG. 19A. It is a block diagram of an optical repeater node according to a ninth embodiment of the present invention. FIG. 20B is a block diagram of a modification of the relay station node shown in FIG. 20A. It is a block diagram of an optical repeater node according to a tenth embodiment of the present invention. It is a block diagram of the optical repeater node by 11th Example of this invention. It is a block diagram of an optical repeater node according to a twelfth embodiment of the present invention. FIG. 24 is a block diagram of a modification of the relay station node shown in FIGS. 20A, 20B, 21 to 23. 1 is a block diagram of an optical device for monitoring a portion of forward and backward propagating light using an optical spectrum analyzer. FIG. 1 is a block diagram of an optical device for monitoring a portion of forward and backward propagating light using an optical spectrum analyzer. FIG.

Claims (31)

An optical amplifier device for use in a system that produces a power transfer from a relatively short wavelength signal to a relatively long wavelength signal,
An amplifier stage coupled to the optical transmission medium;
A monitor for monitoring the power level of the first wavelength band;
Based on the state of the power level of the monitored first wavelength band, at least one first pump light used for signal amplification of the first wavelength band is supplied to the optical transmission medium. The first pump light comprises a pump light source unit that supplies supplementary power to the first wavelength band for the long wavelength channel associated with the state of the first wavelength band.   The optical amplifier apparatus according to claim 1, wherein the monitor monitors a lack of a signal in the first wavelength band.   The optical amplifier apparatus according to claim 1, wherein the monitor monitors a power level of the first wavelength band.   And a controller that switches on the pump light source unit to emit the at least one first pump light in the first wavelength band when the monitor detects the absence of the signal in the first wavelength band. The optical amplifier device according to claim 1.   The optical amplifier device according to claim 1, wherein the pump light source unit supplies a plurality of first pump lights having different wavelengths. The monitor monitors a state of a second wavelength band in addition to the first wavelength band;
The pump light source unit supplies at least one second pump light used for signal amplification of the second wavelength band to the optical transmission medium based on the state of the monitored second wavelength band. 2. The optical amplifier device according to claim 1, wherein supplementary power is supplied to the second wavelength band by the at least one second pump light for a long wavelength channel related to a state of two wavelength bands. The optical amplifier apparatus according to claim 5 , wherein the monitor monitors a power level of the second wavelength band.   Further, when the monitor detects the absence of signals in the first and second wavelength bands, the pump light source unit is switched on, and the at least one first pump light and the at least one second light are respectively switched on. The optical amplifier device according to claim 6, comprising a controller that emits pump light.   The optical amplifier device according to claim 6, wherein the pump light source unit supplies a plurality of second pump lights having different wavelengths.   The optical amplifier device according to claim 1, further comprising an optical circulator that couples the pump light source unit to the optical transmission medium.   The optical amplifier device according to claim 1, further comprising a WDM (wavelength division multiplexing) coupler for coupling the pump light source unit to the optical transmission medium.   The optical amplifier device according to claim 1, wherein the at least one first pump light is propagated through the optical transmission medium in the same direction as the direction in which the long wavelength channel is propagated.   The optical amplifier device according to claim 1, wherein the at least one first pump light is propagated through an optical transmission medium in a direction opposite to a direction in which the long wavelength channel is propagated. The amplifier stage comprises a plurality of amplifier systems;
The optical amplifier device according to claim 1, wherein the at least one first pump light is supplied to an optical transmission medium by one of the plurality of amplifier systems. Said amplifier stage comprises an amplifier system;
2. The optical amplifier device according to claim 1, wherein the at least one first pump light and the at least one second pump light are supplied to an optical transmission medium by each of the amplifier systems. Said amplifier stage comprises an amplifier system;
7. The optical amplifier device according to claim 6, wherein the monitor includes a portion connected to each amplifier system for monitoring the states of the first and second wavelength bands.   An optical switch that selectively couples the optical transmission medium with pump light from the pump light source unit and pump light having a wavelength within the first wavelength band that provides the supplementary power to the pump light. The optical amplifier device according to claim 1, comprising:   The optical amplifier device according to claim 17, wherein the optical switch is provided in front of the amplifier stage.   The optical amplifier device according to claim 17, wherein the optical switch is provided inside an amplifier.   The optical amplifier device according to claim 1, wherein the monitor includes a photodiode.   The optical amplifier apparatus according to claim 1, wherein the monitor includes an optical spectrum analyzer. The monitor monitors a state of a plurality of wavelength bands including the first wavelength band;
The pump light source unit supplies a plurality of pump lights including the at least one first pump unit to an optical transmission medium based on the monitored states of the plurality of wavelength bands, and thus the plurality of pump lights. The optical amplifier apparatus according to claim 1, wherein supplementary power is supplied to a long wavelength channel associated with the states of the plurality of wavelength bands.   The optical amplifier device according to claim 1, wherein the at least one first pump light is Raman pump light. An optical amplifier apparatus for use in a bidirectional system that produces a power transfer from a relatively short wavelength signal to a relatively long wavelength signal,
First and second amplifier systems;
A directional coupling element for coupling the first and second amplifier stages to an optical transmission medium;
Each of the first and second amplifier systems includes an amplifier stage coupled to an optical transmission medium;
A monitor for monitoring the power level of the first wavelength band;
Based on the state of the monitored power level of the first wavelength band, the optical transmission medium is supplied with at least one first pump light used for signal amplification of the first wavelength band, so that the first wavelength An optical amplifier device comprising: a pump light source unit configured to supply supplementary power to the first wavelength band by the at least one first pump light for a long wavelength channel related to a band state. The monitor monitors a state of a second wavelength band in addition to the first wavelength band;
The pump light source unit supplies at least one second pump light to the optical transmission medium based on the monitored state of the second wavelength band, and thus the long wavelength channel to which the state of the second wavelength band is related. 25. The optical amplifier device according to claim 24, wherein power is supplementally supplied by the at least one second pump light. The monitor monitors a state of a plurality of wavelength bands including the first wavelength band;
The pump light source unit supplies a plurality of pump lights including the at least one first pump unit to an optical transmission medium based on the monitored states of the plurality of wavelength bands, and thereby the plurality of pump lights, 25. The optical amplifier apparatus according to claim 24, wherein supplementary power is supplied to a long wavelength channel associated with the states of the plurality of wavelength bands. Monitoring the state of the first wavelength band;
Based on the state of the monitored power level of the first wavelength band, at least one first pump light used for signal amplification of the first wavelength band is supplied to the optical transmission medium, and thus the first A method of controlling an optical amplifier apparatus comprising the steps of causing supplementary power to be supplied to the first wavelength band by the first pump light for a long wavelength channel to which a state of a wavelength band is related. In the monitoring step, the status of the second wavelength band is monitored in addition to the first wavelength band;
In the supplying step, at least one second pump light is supplied to the optical transmission medium based on the state of the monitored second wavelength band, and thus the long wavelength to which the state of the second wavelength band is related. 28. The method of claim 27, wherein supplemental power is provided to the channel by the at least one second pump light. Monitoring the state of a plurality of wavelength bands including the first wavelength band in the monitoring step;
In the supplying step, a plurality of pump lights including at least the first pump unit are supplied based on the power level states of the monitored plurality of wavelength bands, and thus the plurality of wavelength bands are generated by the plurality of pump lights. 28. The method of claim 27, wherein supplemental power is provided for the long wavelength channel to which the state relates. An optical amplifier device;
An optical transmission medium for coupling the optical amplifier device;
One of the optical amplifier devices is an amplifier stage coupled to an optical transmission medium;
A monitor for monitoring the state of the first wavelength band;
Based on the state of the monitored power level of the first wavelength band, at least one first pump light used for signal amplification of the first wavelength band is supplied to the optical transmission medium, and thus the first A pump light source unit configured to supply supplementary power to the first wavelength band by the at least one first pump light for a long wavelength channel associated with a power level state of one wavelength band; An optical transmission system. A bi-directional optical transmission system that produces a power transfer from a relatively short wavelength signal to a relatively long wavelength signal,
An optical amplifier device;
An optical transmission medium for coupling the optical amplifier device;
One of the optical amplifier devices is a first and second amplifier system;
A directional coupling element for coupling the first and second amplifier stages to an optical transmission medium;
Each of the first and second amplifier systems includes an amplifier stage coupled to an optical transmission medium;
A monitor for monitoring the power level of the first wavelength band;
Based on the monitored power level state of the first wavelength band, at least one first pump light used for signal amplification of the first wavelength band is supplied to the optical transmission medium, thereby the first A bidirectional light source comprising a pump light source unit that allows supplemental power to be supplied to the first wavelength band by the at least one first pump light for the long wavelength channel to which the state of the wavelength band relates. Optical transmission system.

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