WO2019003797A1

WO2019003797A1 - Optical fiber amplifier and optical fiber amplification system

Info

Publication number: WO2019003797A1
Application number: PCT/JP2018/021042
Authority: WO
Inventors: 恵一松本; タヤンディエドゥガボリエマニュエルル; 中村　滋; 柳町　成行
Original assignee: 日本電気株式会社
Priority date: 2017-06-28
Filing date: 2018-05-31
Publication date: 2019-01-03
Also published as: JPWO2019003797A1; JP6891957B2

Abstract

Provided is an optical fiber amplifier that is capable of achieving high power utilization efficiency. An optical fiber 1021 allows an optical signal to pass therethrough and amplifies signal intensity of the optical signal when the optical signal is synthesized with excitation light. A plurality of light sources 1031-103N output excitation light, and have excitation light output intensity-power consumption characteristics different from one another. A light source driving means 1061 causes the light sources to output the excitation light. A synthesizing means 1041 synthesizes the excitation light outputted from the light sources with the optical signal. A switch 1071 has excitation light input terminals corresponding to the respective light sources, and an output terminal for outputting the excitation light to the synthesizing means 1041.

Description

Optical fiber amplifier and optical fiber amplification system

The present invention relates to an optical fiber amplifier and an optical fiber amplification system that amplifies the signal strength of an optical signal.

Patent Document 1 describes an example of an optical fiber amplifier that amplifies the signal strength of an optical signal. Patent Document 1 describes a configuration for amplifying the signal intensity of an optical signal by inputting the excitation light output from the excitation light source into a rare earth-doped fiber into which an optical signal is input. A similar configuration is described in Patent Document 2 as well.

Such an optical fiber amplifier is used as an amplifier for relaying an optical signal of an optical fiber communication system because it has high efficiency and high gain, and its gain is almost polarization independent.

Further, Patent Document 3 discloses that an input optical signal is an optical signal in the 1.55 μm band, and discloses that excitation light is light in the 1.48 μm band. Further, Patent Document 3 discloses a configuration including a current excitation light source and a standby excitation light source.

Japanese Patent Application Laid-Open No. 11-112434 Japanese Patent Laid-Open No. 9-116506 Japanese Patent Application Laid-Open No. 6-326383

As an example of a general optical fiber amplifier, the optical fiber amplifier illustrated in FIG. 9 can be considered. The optical fiber 121 illustrated in FIG. 9 is an optical fiber to which rare earth ions are added. Here, the case where erbium ion is added to the optical fiber 121 will be described as an example. Here, it is assumed that erbium ions are added in the range from position A to position B shown in FIG. In the optical fiber 121, as shown in FIG. 9, a first optical isolator 171, a first signal intensity monitor 101, an optical multiplexer 141, a second signal intensity monitor 102, and a second optical isolator 172 are provided.

Further, the optical fiber amplifier includes a gain control circuit 151, one excitation light source 131, and a light source drive circuit 161.

The optical signal Lin is input to the optical fiber 121, and the optical signal Lout after signal strength amplification is output. The first optical isolator 171 and the second optical isolator 172 restrict the propagation direction of the optical signal in a certain direction.

The first signal strength monitor 101 monitors the signal strength of the input optical signal Lin, and notifies the gain control circuit 151 of the signal strength. The gain control circuit 151 calculates gains of the signal strength of the optical signal Lin and the signal strength to be constant so that the signal strength of the output optical signal Lout becomes constant. The second signal strength monitor 102 monitors the signal strength of the optical signal Lout and notifies the gain control circuit 151 of the signal strength. The gain control circuit 151 confirms that the signal strength of the optical signal Lout has a predetermined constant value based on the signal strength notified from the second signal strength monitor 102.

The gain control circuit 151 notifies the light source drive circuit 161 of the gain calculated as described above. The light source drive circuit 161 drives the excitation light source 131 and causes the excitation light source 131 to output excitation light at an excitation light output intensity corresponding to the gain.

The optical multiplexer 141 combines the excitation light output from the excitation light source 131 into an optical signal Lin. In the optical fiber 121 to which erbium ions are added, the pump light is combined with the light signal Lin, whereby the signal strength of the light signal Lin is amplified, and the light signal Lout after signal strength amplification is output.

The light signal is generally a 1.55 μm band light signal. The excitation light is generally light in the 1.48 μm band or light in the 0.98 μm band.

An optical fiber communication system in which a general optical fiber amplifier illustrated in FIG. 9 is used plays an important role in speeding up and increasing the capacity of communication. And, in order to cope with the increase of communication capacity, development of related technology of wavelength multiplexing is actively carried out.

Then, in order to operate the optical fiber amplifier efficiently for a long period of time, at the beginning of operation, narrow the "band used for signal transmission" and, according to the increase in traffic, "band used for signal transmission by wavelength multiplexing. Methods to broaden the Thus, the "band used for signal transmission" changes in accordance with the increase in traffic after the start of operation. The “band used for signal transmission” can also be referred to as a spectrum, a signal usage rate of wavelength division multiplexing (WDM), or a wavelength filling rate. Hereinafter, “a band used for signal transmission” may be simply referred to as a band.

The optical fiber amplifier shown in FIG. 9 includes one excitation light source 131. Then, the excitation light source 131 is designed in accordance with the maximum band of the optical signal. That is, the excitation light source 131 is designed so that excitation light with high excitation light output intensity can be output when the “band used for signal transmission” becomes wide. FIG. 10 is a schematic view showing the excitation light output intensity versus power consumption characteristics of such an excitation light source 131. As shown in FIG. The horizontal axis shown in FIG. 10 is the excitation light output intensity of the excitation light source. Here, it can be said that the excitation light output intensity is approximately proportional to the "band used for signal transmission". The vertical axis shown in FIG. 10 is the power consumption of the excitation light source. As described above, when the “band used for signal transmission” becomes wide, the pumping light source 131 designed to be able to output pumping light with high pumping light output intensity consumes less power even if the band is narrow. It doesn't fall that much. Then, for example, in the state where the band is narrowed as in the operation start, the power consumption increases.

As indicated by a broken line in FIG. 10, the power consumption is preferably proportional to the excitation light output intensity. However, as described above, even when the band is narrow, the power consumption does not decrease so much, and when the band is narrowed, the power consumption becomes large.

When priority is given to reducing power consumption and the power consumption is designed to be small in a narrow band, when the band is broadened, it is not possible to output pumping light with high pumping light output intensity.

Therefore, an object of the present invention is to provide an optical fiber amplifier and an optical fiber amplification system capable of realizing high power utilization efficiency.

The optical fiber amplifier according to the present invention is an optical fiber that passes an optical signal and amplifies the signal intensity of the optical signal when the excitation light is combined with the optical signal, and a plurality of light sources that output the excitation light. A plurality of light sources having different excitation light output intensity versus power consumption characteristics, light source driving means for outputting excitation light from the light sources, combining means for synthesizing excitation lights output from the light sources into optical signals, and each individual light source And a switch having an input end of excitation light corresponding to the light source and an output end for outputting the excitation light to the synthesizing means.

According to the present invention, high power utilization efficiency can be realized.

It is a block diagram showing an example of composition of an optical fiber amplifier of a 1st embodiment of the present invention. It is a schematic diagram showing the excitation light output intensity versus power consumption characteristic of several excitation light sources. It is a schematic diagram which shows the difference of the power consumption of a general optical fiber amplifier and the optical fiber amplifier by this invention. It is a block diagram which shows the structural example of the optical fiber amplifier of the 2nd Embodiment of this invention. It is a block diagram which shows the structural example of the optical fiber amplifier of the 3rd Embodiment of this invention. It is a block diagram which shows the structural example of the optical fiber amplification system of the 4th Embodiment of this invention. It is a block diagram which shows the structural example of the optical fiber amplifier of the 5th Embodiment of this invention. It is a block diagram showing an outline of the present invention. It is a schematic diagram which shows the example of a common optical fiber amplifier. It is a schematic diagram which shows the excitation light output intensity versus power consumption characteristic of the excitation light source provided in a common optical fiber amplifier.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As in the case described above, in each embodiment, "a band used for signal transmission" may be simply referred to as a band. As mentioned above, the "band used for signal transmission" can also be called spectrum, WDM signal usage rate, or wavelength filling rate.

Embodiment 1
FIG. 1 is a block diagram showing an example of configuration of an optical fiber amplifier according to a first embodiment of the present invention. The optical fiber amplifier according to the first embodiment includes a first signal strength monitor 1, a second signal strength monitor 2, a bandwidth monitor 3, a first optical isolator 11, and a second optical isolator 12. An optical fiber 21, a plurality of excitation light sources 31 to 3 N, an optical multiplexer 41, a gain control circuit 51, a light source drive circuit 61, a switch 71, an output monitor 81, and a switch control circuit 91.

The optical fiber 21 is an optical fiber doped with rare earth ions. Here, the case where erbium ion is added to the optical fiber 21 will be described as an example. Further, it is assumed that erbium ions are added in the range from position A to position B shown in FIG.

Also, the optical fiber amplifier of the first embodiment includes one optical fiber 21. In the present embodiment, the optical fiber 21 includes one core.

The optical fiber 21 passes an optical signal. When the optical fiber 21 is doped with a rare earth ion (in this example, an erbium ion) and the excitation light is synthesized to the optical signal, the signal intensity of the optical signal is amplified.

That is, the optical fiber 21 is an optical fiber that passes the optical signal and amplifies the signal intensity of the optical signal when the excitation light is combined with the optical signal.

In the example shown in FIG. 1, the optical signal input to the optical fiber 21 is denoted as Lin. Also, the amplified optical signal output from the optical fiber is referred to as Lout. Further, for convenience, in the optical fiber 21, the side to which the optical signal Lin is input is referred to as the upstream side, and the side to which the optical signal Lout is output is referred to as the downstream side.

In the optical fiber 21, the first signal intensity monitor 1 is connected upstream of the start position A of the erbium ion doping range, and the first optical isolator 11 is connected further upstream. Further, in the optical fiber 21, the second signal intensity monitor 2 is connected downstream of the end position B of the addition range of erbium ions, and the second optical isolator is connected further downstream.

The first signal strength monitor 1 and the second signal strength monitor 2 are connected to the gain control circuit 51, respectively. Furthermore, the gain control circuit 51 is connected to the light source drive circuit 61.

In addition, a band monitor 3 is connected between the first optical isolator 11 and the first signal strength monitor 1. Further, the band monitor 3 is connected to the light source drive circuit 61.

The excitation light sources 31 to 3 N are connected to the light source drive circuit 61.

The switch 71 includes an input end of excitation light corresponding to the excitation light source for each individual excitation light source. In the example shown in FIG. 1, the switch 71 includes input ends I1 to IN. For example, the input end I1 corresponds to the excitation light source 31, and the input end I2 corresponds to the excitation light source 32. The other inputs of the switch 71 also correspond to one excitation light source.

The light output ends of the respective excitation light sources 31 to 3N are connected to the corresponding input ends I1 to IN of the switch 71. For example, the light output end of the excitation light source 31 is connected to the input end I1 of the switch 71.

The switch 71 also includes an output end O1 for outputting the input excitation light to the optical multiplexer 41. In the present embodiment, the switch 71 includes one output end O1. The output end O1 is connected to the optical multiplexer 41. Further, the optical multiplexer 41 is provided in the addition range of erbium ions in the optical fiber 21.

The light output terminals of the excitation light sources 31 to 3N are connected to the output monitor 81.

The output monitor 81 is connected to the light source drive circuit 61 and the switch control circuit 91. The switch control circuit 91 is connected to the switch 71.

Next, individual elements will be described.

The respective excitation light sources 31 to 3N are excitation light sources having different excitation light output intensity versus power consumption characteristics. FIG. 2 is a schematic diagram showing excitation light output intensity versus power consumption characteristics of a plurality of excitation light sources. The horizontal axis shown in FIG. 2 is the excitation light output intensity of the excitation light source. Here, it can be said that the excitation light output intensity is approximately proportional to the "band used for signal transmission". As will be described later, the gain calculated by the gain control circuit 51 tends not to change much. The vertical axis shown in FIG. 2 is the power consumption of the excitation light source. FIG. 2 schematically shows an example of the characteristics of the excitation light sources 31 to 35. The lower the power consumption, the smaller the upper limit of the excitation light output intensity. For example, in the example shown in FIG. 2, from the viewpoint of reducing power consumption, the

excitation light sources

31, 32, 33, 34, 35 are preferred in this order. However, although the excitation light source 31 can output excitation light up to the excitation light output intensity R1, it can not output excitation light with a higher excitation light output intensity. Similarly, the upper limit of the excitation light output intensity of the excitation light that can be output by the

excitation light sources

32, 33, 34 is R2, R3, R4, respectively.

For example, in the case of outputting the excitation light of the excitation light output intensity a (see FIG. 2), it is preferable to output the excitation light from the excitation light source 31 with the lowest power consumption. Further, in the case of outputting the excitation light of the excitation light output intensity b (see FIG. 2), since R1 <b, the excitation light source 31 can not be used. In this case, it is preferable to output excitation light from the excitation light source 32 which consumes the least power other than the excitation light source 31.

In the present invention, high power utilization efficiency is realized by selecting an appropriate excitation light source from among a plurality of excitation light sources having different excitation light output intensity versus power consumption characteristics.

Each of the excitation light sources 31 to 3N is provided with a Peltier cooler, respectively. And, the maximum heat absorption of the individual Peltier coolers corresponding to the individual excitation light sources is different. As described above, by making the maximum heat absorption amount of the Peltier coolers provided in the excitation light sources different from each other, it is possible to change the excitation light output intensity vs. power consumption characteristics of the respective excitation light sources 31 to 3N. However, not only the maximum heat absorption amount of the Peltier cooler but also other factors may be changed to change the excitation light output intensity versus power consumption characteristics of each of the excitation light sources 31 to 3N.

The wavelength of the excitation light output from each of the excitation light sources 31 to 3N is common. For example, the wavelength of the excitation light output from each of the excitation light sources 31 to 3N is common to the 1.48 μm band. Further, for example, the wavelength of the excitation light output from each of the excitation light sources 31 to 3N may be common in the 0.98 μm band.

The wavelength of the input light signal Lin is 1.55 μm band.

The first optical isolator 11 and the second optical isolator 12 restrict the propagation direction of the optical signal in a fixed direction.

The first signal strength monitor 1 monitors the signal strength of the input optical signal Lin, and notifies the gain control circuit 51 of the signal strength.

The gain control circuit 51 is a gain between the signal strength of the optical signal Lin notified from the first signal strength monitor 1 and the signal strength to be constant so that the signal strength of the output optical signal Lout becomes constant. Calculate In other words, the gain control circuit 51 calculates the gain when amplifying the signal strength of the optical signal Lin in the optical fiber 21 to a predetermined signal strength. The gain control circuit 51 may store in advance the value of the signal strength to be constant after amplification, and the gain control circuit 51 may calculate the gain of the signal strength of the optical signal Lin and the signal strength thereof.

Further, the second signal strength monitor 2 monitors the signal strength of the optical signal Lout to be outputted, and notifies the gain control circuit 51 of the signal strength. The gain control circuit 51 confirms that the signal strength of the optical signal Lout has a predetermined constant value based on the signal strength notified from the second signal strength monitor 2. If the signal strength of the optical signal Lout does not reach a predetermined constant value, the gain control circuit 51 adjusts the calculated gain. For example, it is assumed that the signal strength of the optical signal Lout should be constant at 100. If the signal strength of the actual optical signal Lout notified from the second signal strength monitor 2 is larger than 100, the gain control circuit 51 adjusts so as to reduce the value of the calculated gain. In addition, if the signal strength of the actual optical signal Lout notified from the second signal strength monitor 2 is smaller than 100, the gain control circuit 51 adjusts so as to increase the value of the calculated gain.

The gain control circuit 51 notifies the light source drive circuit 61 of the calculated gain.

The band monitor 3 monitors the band (the band used for signal transmission) of the optical signal Lin passing through the optical fiber 21 and notifies the light source drive circuit 61 of the band.

The light source drive circuit 61 calculates the product of the gain notified from the gain control circuit 51 and the band notified from the band monitor 3. Then, based on the product of the gain and the band, the light source drive circuit 61 selects one of the plurality of excitation light sources 31 to 3N that causes excitation light to be output.

The light source drive circuit 61 stores in advance the correspondence between the range of the product of the gain and the band (numerical range) and the excitation light source to be selected. For example, the light source drive circuit 61 stores in advance information indicating a correspondence such that the range “0 or more and less than T1” corresponds to the excitation light source 31 and the range “more than T1 and less than T2” corresponds to the excitation light source 32. ing. Here, each range is determined so as not to overlap and to be continuous across the boundary. In addition, the smaller the value range is, the smaller the power consumption is associated with the excitation light source.

For example, in the above example, it is assumed that the product of the gain and the band belongs to the range “0 or more and less than T1”. In this case, the light source drive circuit 61 selects the excitation light source 31 corresponding to the range “0 or more and less than T1”.

The light source drive circuit 61 drives one selected excitation light source, and causes the excitation light source to output excitation light. At this time, the light source drive circuit 61 causes the excitation light source to output excitation light at the excitation light output intensity corresponding to the product of the gain and the band. The light source drive circuit 61 increases the pump light output intensity as the product of the gain and the band is larger, and lowers the pump light output intensity as the product of the gain and the band is smaller.

The light source drive circuit 61 switches the excitation light source for outputting the excitation light according to the instruction of the output monitor 81 after selecting one excitation light source based on the product of the gain and the band.

The gain control circuit 51 periodically notifies the light source drive circuit 61 of the gain, for example. The band monitor 3 also periodically notifies the light source drive circuit 61 of the band, for example. The light source drive circuit 61 changes the pump light output intensity of the pump light from the pump light source outputting the pump light according to the product of the gain and the band, when the gain and the band are newly notified. As described above, the light source drive circuit 61 switches the excitation light source for outputting the excitation light according to the instruction of the output monitor 81 after selecting one excitation light source once based on the product of the gain and the band. Therefore, when the gain and the band are newly notified, the light source drive circuit 61 controls the excitation light output intensity, but does not reselect the excitation light source for outputting the excitation light.

The output monitor 81 monitors the excitation light output intensity of the excitation light output from the light output end of the excitation light sources 31 to 3N. The output monitor 81 may include, for example, a photodiode as a sensor for monitoring the excitation light output intensity. However, the sensor for monitoring the excitation light output intensity may be a sensor other than a photodiode.

Specifically, the output monitor 81 monitors the excitation light output intensity of the excitation light output from the excitation light source driven by the light source drive circuit 61.

Further, the output monitor 81 stores in advance a range of excitation light output intensity determined for each excitation light source. The output monitor 81 has, for example, a range “0 or more and less than R1 (see FIG. 2)” of the excitation light output intensity defined for the excitation light source 31 and a range “R1 or more than R2 determined for the excitation light source 32 The range “R2 or more and less than R3 (see FIG. 2)” of the excitation light output intensity determined for the excitation light source 33 and the like are stored in advance. The range of excitation light output intensity determined for each excitation light source is determined so as not to overlap and to be continuous across the boundary.

It is assumed that the product of the gain and the band is changed by changing either one or both of the gain calculated by the gain control circuit 51 and the band of the optical signal Lin monitored by the band monitor 3. Then, the light source drive circuit 61 changes the excitation light output intensity of the excitation light from the excitation light source outputting the excitation light according to the product after the change. When the output light intensity of the excitation light output from the excitation light source driven by the light source drive circuit 61 becomes equal to the boundary value of the range of the excitation light output intensity defined for the excitation light source, the output monitor 81 The light source drive circuit 61 is instructed to switch the excitation light source for outputting the excitation light to the excitation light source corresponding to the adjacent range of the range. Further, the output monitor 81 instructs the switch control circuit 91 to connect the input end of the switch 71 corresponding to the switched excitation light source and the output end O1 of the switch 71.

The light source drive circuit 61 switches the excitation light source for outputting the excitation light according to the instruction of the output monitor 81.

Further, the switch control circuit 91 connects the input end of the switch 71 corresponding to the switched excitation light source and the output end O1 of the switch 71 according to the instruction of the output monitor 81. Note that connecting the input end and the output end of the switch 71 means that the excitation light input to the input end is output from the output end. It can be said that the switch control circuit 91 controls the input terminal connected to the output terminal O1.

Hereinafter, as shown in FIG. 1, the switch 71 provided with N input ends and one output end O1 is referred to as an N × 1 switch 71.

The N × 1 switch 71 is a switch that can operate on 0.98 μm band excitation light and 1.48 μm band excitation light, or both, and is a switch having a maximum insertion loss of 1 dB or less.

The optical multiplexer 41 combines the excitation light output from the output end O1 of the N × 1 switch 71 into an optical signal Lin.

The individual excitation light sources 31 to 3N are each realized by, for example, a semiconductor laser diode. The first signal strength monitor 1, the second signal strength monitor 2, and the band monitor 3 are each realized by a dedicated sensor.

Further, the gain control circuit 51, the light source drive circuit 61, the output monitor 81, and the switch control circuit 91 are each realized by, for example, a dedicated processor. The processor operating as the output monitor 81 includes a sensor for monitoring the excitation light output intensity. Further, the gain control circuit 51, the light source drive circuit 61, the output monitor 81, and the switch control circuit 91 may be realized by one processor having the function of each element.

Next, an example of the operation of the optical fiber amplifier according to the first embodiment will be described.

An optical signal Lin is input to the optical fiber 21. The wavelength of the light signal Lin is 1.55 μm band. The first optical isolator 11 limits the propagation direction of the optical signal to a fixed direction.

The band monitor 3 monitors the band (the band used for signal transmission) of the optical signal Lin passing through the optical fiber 21 and notifies the light source drive circuit 61 of the band. Here, at the initial stage of operation of the optical fiber amplifier, the traffic (the amount of communication) by the optical signal is small, and the value of the band monitored by the band monitor 3 is also a small value.

The first signal strength monitor 1 monitors the signal strength of the optical signal Lin and notifies the gain control circuit 51 of the signal strength.

The gain control circuit 51 is a gain between the signal strength of the optical signal Lin notified from the first signal strength monitor 1 and the signal strength to be constant so that the signal strength of the output optical signal Lout becomes constant. That is, the gain at the time of amplifying the signal strength of the optical signal Lin to a predetermined signal strength is calculated. As described above, the gain control circuit 51 stores in advance the value of the signal strength to be constant after amplification, and the gain control circuit 51 calculates the gain of the signal strength of the optical signal Lin and the signal strength thereof. do it. The gain control circuit 51 notifies the light source drive circuit 61 of the calculated gain.

The traffic tends to increase as the operation time passes, and the band of the optical signal Lin (the band used for signal transmission) tends to increase. Also, the gain calculated by the gain control circuit 51 tends not to change much. However, the band of the optical signal Lin may be reduced. Also, the gain does not always change at all.

The light source drive circuit 61 calculates the product of the gain notified from the gain control circuit 51 and the band notified from the band monitor 3. As described above, in the light source drive circuit 61, for example, the excitation light source 31 corresponds to the range “0 or more and less than T1”, and the correspondence relationship such as the excitation light source 32 corresponds to the range “T1 or more and less than T2” Information to be shown is stored in advance. In addition, the smaller the value range is, the smaller the power consumption is associated with the excitation light source. The light source drive circuit 61 selects one excitation light source corresponding to the range to which the calculated product belongs, from the plurality of excitation light sources 31 to 3N.

Here, it is assumed that the optical fiber amplifier is in an initial state of operation start, and the band value of the input optical signal Lin is a small value. The product of the gain and the band is also small, and the product of the gain and the band belongs to the range “0 or more and less than T1”. At this time, the light source drive circuit 61 selects the excitation light source 31 corresponding to the range “0 or more and less than T1”.

Then, the light source drive circuit 61 drives the selected excitation light source 31 and causes the excitation light source 31 to output excitation light at an excitation light output intensity corresponding to the product of the gain and the band. As described above, the light source drive circuit 61 increases the pumping light output intensity as the product of the gain and the band increases, and the pumping light output intensity decreases as the product of the gain and the band decreases. Do.

Here, when the pumping light source 31 selected by the light source driving circuit 61 outputs the pumping light of the pumping light output intensity corresponding to the product of the gain and the band, the pumping light output intensity vs. power consumption characteristic has the highest efficiency. The excitation light source is As already described, it is preferable that the power consumption be proportional to the excitation light output intensity. Then, assuming that the excitation light output intensity and the power consumption have an ideal proportional relationship, the proportional relationship can be represented by a straight line 19 indicated by a broken line in FIG. Under the determined excitation light output intensity, the excitation light source with the highest efficiency of the excitation light output intensity versus the power consumption characteristic is the coordinate represented by (the determined excitation light output intensity, the consumed power), It is an excitation light source closest to the straight line.

For example, it is assumed that the value of the pump light output intensity corresponding to the product of the gain and the band is “a” shown in FIG. When the excitation light of the excitation light output intensity a is output, the power consumption of the excitation light source 31 is the smallest. In the vicinity of the excitation light output intensity a, among the coordinates (a, power consumption) determined for each excitation light source, the coordinates (a, power consumption) corresponding to the excitation light source 31 are closest to the straight line 19. Therefore, when the value of the product of the gain and the band is small and the pumping light output intensity is also small, the pumping light output intensity vs. power consumption characteristic of the pumping light source 31 has the highest efficiency.

In the initial stage of operation, the input end I1 and the output end O1 may be connected in the initial state in the N × 1 switch 71 based on the fact that the traffic by the optical signal is small. Alternatively, when the light source drive circuit 61 selects the excitation light source based on the product of the gain and the band, the light source drive circuit 61 switches the connection between the input end corresponding to the excitation light source and the output end O1. , And the switch control circuit 91 may connect the instructed input end and the output end O1 according to the instruction. In this case, the light source drive circuit 61 and the switch control circuit 91 are connected.

The excitation light source 31 is driven by the light source drive circuit 61, and outputs excitation light of the excitation light output intensity determined by the light source drive circuit 61. The excitation light is input to the input end I1 corresponding to the excitation light source 31 in the N × 1 switch 71, and the N × 1 switch 71 outputs the excitation light input to the input end I1 from the output end O1. Since the N × 1 switch 71 is a switch having a maximum insertion loss of 1 dB or less, almost all the excitation light input from the input end is output from the output end O1.

The mode in which the optical multiplexer 41 combines the excitation light into the optical signal may be a core individual system or another system. The core individual system is a system in which excitation light is combined with an optical signal passing through the inside of the core by inputting the excitation light to the core in the optical fiber 21. Alternatively, the optical multiplexer 41 may combine the excitation light with the optical signal passing through the core by inputting the excitation light to the cladding present around the core in the optical fiber 21.

The signal intensity of the optical signal Lin is amplified when the optical signal Lin in which the excitation light is synthesized passes through the addition range of the rare earth ion (erbium ion in this example) in the optical fiber 21. In the optical signal Lin, the pump light of the pump light output intensity according to the product of the band of the optical signal Lin and the gain calculated by the gain control circuit 51 is synthesized. As a result, the signal strength of the light signal Lin is amplified to a constant signal strength and output as the light signal Lout.

At this time, the second signal strength monitor 2 monitors the signal strength of the optical signal Lout, and notifies the gain control circuit 51 of the signal strength. The gain control circuit 51 confirms that the signal strength of the optical signal Lout has a predetermined constant value based on the signal strength notified from the second signal strength monitor 2. If the signal strength of the optical signal Lout does not reach a predetermined constant value, the gain control circuit 51 adjusts the calculated gain thereafter.

The second optical isolator 12 limits the propagation direction of the optical signal to a fixed direction.

The gain control circuit 51 periodically notifies the light source drive circuit 61 of the gain, for example. The band monitor 3 also periodically notifies the light source drive circuit 61 of the band, for example. Then, the light source drive circuit 61 controls the excitation light output intensity of the excitation light from the excitation light source outputting the excitation light according to the product of the gain and the band. Therefore, when the product of the gain and the band changes, the excitation light output intensity of the excitation light output from the excitation light source driven by the light source drive circuit 61 also changes.

The output monitor 81 monitors the excitation light output intensity of the excitation light output from the light output end of each of the excitation light sources 31 to 3N. Then, when the excitation light output intensity of the excitation light of the excitation light source outputting the excitation light becomes the boundary value of the range of the excitation light output intensity defined for the excitation light source, the output monitor 81 It instructs the light source drive circuit 61 to switch the excitation light source outputting the excitation light to the excitation light source corresponding to the range of the excitation light output intensity adjacent to the boundary value. The light source drive circuit 61 switches the excitation light source for outputting the excitation light according to the instruction.

Further, the output monitor 81 instructs the switch control circuit 91 to connect the input end of the switch 71 corresponding to the switched excitation light source and the output end O1 of the switch 71. The switch control circuit 91 connects the input end of the switch 71 corresponding to the switched excitation light source and the output end O1 of the switch 71 according to the instruction.

Hereinafter, an example of switching of the excitation light source based on the instruction of the output monitor 81 will be described with reference to FIG. For example, as the product of gain and band increases, the light source drive circuit 61 increases the pump light output intensity of the pump light to be output to the pump light source 31, and the pump light output intensity becomes the boundary value R1 (see FIG. 2). Suppose that it became. Then, as viewed from the range “0 or more and less than R1 (see FIG. 2)” of the excitation light output intensity defined for the excitation light source 31, the adjacent range via the boundary value R1 is “R1 or more and less than R2 (see FIG. 2) The range “R1 or more and less than R2” is a range defined for the excitation light source 32. Therefore, the output monitor 81 instructs the light source drive circuit 61 to switch the excitation light source outputting the excitation light from the excitation light source 31 to the excitation light source 32, and the light source drive circuit 61 outputs the excitation light. The excitation light source 31 is switched to the excitation light source 32.

At this time, the output monitor 81 instructs the switch control circuit 91 to connect the input end I2 of the switch 71 corresponding to the excitation light source 32 after switching to the output end O1 of the switch 71, and performs switch control The circuit 91 connects the input end I2 and the output end O1.

As a result, the product of the gain and the band increases, and when the excitation light output intensity exceeds the boundary value R1, the excitation light source that outputs the excitation light is switched from the excitation light source 31 to the excitation light source 32. Then, the excitation light output from the excitation light source 32 is synthesized by the optical multiplexer 41 into the optical signal Lin.

Although the above-mentioned example showed the example in the case of making excitation light output intensity increase, the switching of the excitation light source in the case of reducing excitation light output intensity is the same. For example, it is assumed that the excitation light source 32 outputs an excitation light source. Then, it is assumed that the pump light output intensity becomes the boundary value R1 (see FIG. 2) due to the decrease of the product of the gain and the band. As seen from the range “R1 or more and less than R2 (see FIG. 2)” of the excitation light output intensity defined for the excitation light source 32, the adjacent range via the boundary value R1 is “0 or more and less than R1 (see FIG. 2)”. This range “0 or more and less than R1” is a range defined for the excitation light source 31. Therefore, the output monitor 81 instructs the light source drive circuit 61 to switch the excitation light source for outputting the excitation light from the excitation light source 32 to the excitation light source 31, and the light source drive circuit 61 outputs the excitation light. The excitation light source 32 is switched to the excitation light source 31.

At this time, the output monitor 81 instructs the switch control circuit 91 to connect the input end I1 of the switch 71 corresponding to the excitation light source 31 after switching and the output end O1 of the switch 71, and performs switch control The circuit 91 connects the input end I1 to the output end O1.

As a result, the product of the gain and the band decreases, and when the excitation light output intensity exceeds the boundary value R1, the excitation light source that outputs the excitation light is switched from the excitation light source 32 to the excitation light source 31. Then, the excitation light output from the excitation light source 31 is synthesized by the optical multiplexer 41 into the optical signal Lin.

In addition, as an aspect in which the product of gain and band changes, an aspect in which the product changes by changing only the band, an aspect in which the product changes by changing only the gain, and a change in both gain and band There is an aspect in which the product changes. The manner in which the product of the gain and the band changes may be any of these.

According to the present embodiment, the optical fiber amplifier comprises a plurality of excitation light sources each having different excitation light output intensity versus power consumption characteristics. Then, the light source drive circuit 61 selects one pumping light source based on the product of the gain notified from the gain control circuit 51 and the band notified by the band monitor 3 (the band of the input light Lin). Therefore, the light source drive circuit 61 can output the excitation light from the excitation light source which has the highest efficiency of the excitation light output intensity versus the power consumption characteristic. Therefore, high power utilization efficiency can be realized.

Furthermore, the light source drive circuit 61 causes the excitation light source to output excitation light at an excitation light output intensity corresponding to the above product. The output monitor 81 instructs the light source drive circuit 61 to switch the excitation light source when the product of the gain and the band changes and the excitation light output intensity reaches the boundary value of the excitation light output intensity range defined for the excitation light source. . Further, the output monitor 81 instructs the switch control circuit 91 to connect the input end I1 of the switch 71 corresponding to the switched excitation light source 31 and the output end O1 of the switch 71. Therefore, even if the pump light output intensity changes according to the change of the product of the gain and the band, the optical fiber amplifier causes the pump light source to output the pump light with the highest efficiency of the pump light output intensity versus the power consumption. be able to. Also in this respect, high power utilization efficiency can be realized.

FIG. 3 is a schematic view showing the difference in power consumption between the general optical fiber amplifier shown in FIG. 9 and the optical fiber amplifier according to the present invention. The horizontal axis shown in FIG. 3 indicates the passage of time (year). The left vertical axis shows traffic. As traffic increases, the bandwidth used for signaling also increases. The right vertical axis indicates power consumption. Also, the solid line graph shown in FIG. 3 indicates changes in traffic. Generally, after the start of operation of the optical fiber amplifier, the traffic increases with the passage of time, and the band of the input signal Lin also increases. In addition, as shown in FIG. 3, temporary increase in traffic due to disaster or the like may occur. The graph of the alternate long and short dash line shown in FIG. 3 schematically shows the change in power consumption in the general optical fiber amplifier (see FIG. 9) according to the change in traffic shown in FIG. The broken line graph shown in FIG. 3 schematically shows the change of the power consumption of the present invention according to the change of the traffic shown in FIG. The power consumption of the present invention is lower than the general optical fiber amplifier shown in FIG. 9, and according to the present invention, high power utilization efficiency can be realized.

Next, a modification of the first embodiment will be described. The modifications shown below are applicable to each embodiment described later. As described above, the gain calculated by the gain control circuit 51 tends not to change much. Therefore, the light source drive circuit 61 may select the excitation light source based on only the band notified from the band monitor 3. However, the light source drive circuit 61 causes the selected excitation light source to output excitation light at an excitation light output intensity corresponding to the product of the gain and the band.

In this case, the light source drive circuit 61 stores in advance the correspondence between the range (numerical range) of the band and the excitation light source to be selected. For example, the light source drive circuit 61 stores in advance information indicating a correspondence such that the range “0 or more and less than W1” corresponds to the excitation light source 31 and the range “W1 or more and less than W2” corresponds to the excitation light source 32. . Here, each range is determined so as not to overlap and to be continuous across the boundary. In addition, the smaller the value range is, the smaller the power consumption is associated with the excitation light source.

For example, in the above example, it is assumed that the value of the band (the band used for signal transmission) of the input signal Lin notified from the band monitor 3 belongs to the range “0 or more and less than W1”. In this case, the light source drive circuit 61 selects the excitation light source 31 corresponding to the range “0 or more and less than W1”. Then, the light source drive circuit 61 causes the pumping light source 31 to output pumping light at a pumping light output intensity corresponding to the product of the gain (the gain notified from the gain control circuit 51) and the band thereof.

Also in this case, the same effect as that of the first embodiment can be obtained.

In the above modification, it is assumed that the value of the band notified from the band monitor 3 is small and, for example, the excitation light source 31 is selected. Further, the gain notified from the gain control circuit 51 is large, the value of the product of the gain and the band is large, and the pumping light output intensity determined for the pumping light source 31 according to the product of the gain and the band is determined. Greater than the upper limit of Then, the light source drive circuit 61 causes the selected excitation light source 31 to output excitation light at the excitation light output intensity R1. As a result, the output monitor 81 immediately instructs switching of the excitation light source that outputs the excitation light. As described above, in the above modification, the output monitor 81 may instruct switching of the excitation light source immediately after the light source drive circuit 61 selects the excitation light source and causes the excitation light source to output excitation light. .

Embodiment 2
FIG. 4 is a block diagram showing a configuration example of an optical fiber amplifier according to a second embodiment of the present invention. The same components as in the first embodiment are given the same reference numerals as in FIG. 1 and the description will be omitted.

The optical fiber amplifier according to the second embodiment includes a switching instruction circuit 83 and a plurality of excitation light output intensity monitors 82 instead of the output monitor 81 according to the first embodiment. The excitation light output intensity monitor 82 and the excitation light sources 31 to 3N correspond one to one, and the individual excitation light output intensity monitors 82 are integrated into the corresponding excitation light sources.

Each excitation light output intensity monitor 82 is connected to the switching instruction circuit 83. The switching instruction circuit 83 is connected to the light source drive circuit 61 and the switch control circuit 91.

Then, each excitation light output intensity monitor 82 monitors the excitation light output intensity of the excitation light output from the light output end of the corresponding excitation light source, and the monitoring result (excitation light output intensity of the output excitation light) Is notified to the switching instruction circuit 83.

The switching instruction circuit 83 stores in advance a range of excitation light output intensity determined for each excitation light source. The switching instruction circuit 83 has, for example, a range “0 or more and less than R1 (see FIG. 2)” of excitation light output intensity determined for the excitation light source 31 and a range “R1 or more R2 for excitation light output intensity determined for the excitation light source 32”. Less than (see FIG. 2), a range of “R2 or more and less than R3 (see FIG. 2)” of the excitation light output intensity determined for the excitation light source 33, etc. are stored in advance. This point is the same as the output monitor 81 in the first embodiment.

Then, the switching instruction circuit 83 receives notification of the excitation light output intensity from the excitation light output intensity monitor 82 corresponding to the excitation light source outputting the excitation light. Then, when the excitation light output intensity reaches a boundary value of the range of excitation light output intensities defined for the excitation light source, the switching instruction circuit 83 sends the excitation light to the light source drive circuit 61. It is instructed to switch the excitation light source to be output to the excitation light source corresponding to the range of the adjacent excitation light output intensity via the boundary value. The light source drive circuit 61 switches the excitation light source for outputting the excitation light according to the instruction.

Further, it instructs the switch control circuit 91 to connect the input end of the switch 71 corresponding to the switched excitation light source and the output end O1 of the switch 71. The switch control circuit 91 connects the input end of the switch 71 corresponding to the switched excitation light source and the output end O1 of the switch 71 according to the instruction.

The switching instruction circuit 83 and the plurality of excitation light output intensity monitors 82 are a part (a plurality of excitation light output intensity monitors 82) for monitoring the excitation light output intensity of the excitation light in the output monitor 81 in the first embodiment It has a configuration separated into a portion (switching instruction circuit 83) for realizing other functions. The function of the portion including the switching instruction circuit 83 and the plurality of excitation light output intensity monitors 82 is the same as the function of the output monitor 81 in the first embodiment.

Each excitation light output intensity monitor 82 is realized by, for example, a photodiode. The switching instruction circuit 83 is realized by, for example, a dedicated processor. The gain control circuit 51, the light source drive circuit 61, the switching instruction circuit 83, and the switch control circuit 91 may be realized by one processor having the function of each element.

Also in the second embodiment, the same effects as in the first embodiment can be obtained.

The configuration in which the switching instruction circuit 83 and the plurality of excitation light output intensity monitors 82 are provided instead of the output monitor 81 is also applicable to each embodiment described later.

Embodiment 3
FIG. 5 is a block diagram showing a configuration example of an optical fiber amplifier according to a third embodiment of the present invention. The same components as in the first embodiment are given the same reference numerals as in FIG. 1 and the description will be omitted.

The optical fiber amplifier according to the third embodiment includes one optical fiber 21 a instead of the optical fiber 21 in the first embodiment. The optical fiber 21 in the first embodiment is an optical fiber including one core, whereas the optical fiber 21 a in the third embodiment is a multi-core optical fiber including a plurality of cores. In this embodiment, the optical fiber 21a will be described as including K cores.

The optical fiber 21a is doped with rare earth ions (here, erbium ions). Here, it is assumed that erbium ions are added in the range from position A to position B shown in FIG.

In addition, a plurality of optical signals Lin1 to LinK are input to the optical fiber amplifier of the present embodiment. Then, the optical fiber amplifier amplifies each optical signal, and outputs the amplified optical signal as optical signals Lout1 to LoutK.

In the present embodiment, a fiber bundle fan out 87 is provided on the upstream side of the first signal strength monitor 1, and the optical fiber 21a and K optical fibers 911 to 91 K are connected via the fiber bundle fan out 87. It is done. Each of the K optical fibers 911 to 91K includes one core. In addition, first

optical isolators

111, 112,..., 11K are separately connected to the K optical fibers 911 to 91K, respectively (see FIG. 5).

Similarly, a fiber bundle fan-in 88 is provided downstream of the second signal strength monitor 2, and the optical fiber 21a and K optical fibers 921 to 92 K are connected via the fiber bundle fan-in 88. ing. Each of the K optical fibers 921 to 92K includes one core. In addition, second optical isolators 121, 122, ..., 12K are separately connected to the K optical fibers 921 to 92K, respectively (see Fig. 5).

The fiber bundle fan-out 87 and the fiber bundle fan-in 88 are members of a common configuration. Each of the fiber bundle fan-out 87 and the fiber bundle fan-in 88 is a member for connecting a plurality of optical fibers each including one core and a single optical fiber 21 a including a plurality of cores. More specifically, it is a member for connecting one core respectively contained in a plurality of optical fibers and each core contained in one optical fiber 21a in a one-to-one manner. In the fiber bundle fan-out 87, K optical fibers 911 to 91K exist on the upstream side, and one optical fiber 21a exists on the downstream side (see FIG. 5). Further, in the fiber bundle fan-in 88, one optical fiber 21a exists on the upstream side, and K optical fibers 921 to 92K exist on the downstream side (see FIG. 5).

The input optical signals Lin1 to LinK are separately input to the optical fibers 911 to 91K.

Similarly, the output optical signals Lout1 to LoutK are separately output from the optical fibers 921 to 92K.

In addition, the optical multiplexer 41a in the present embodiment is an optical multiplexer that combines excitation light into an optical fiber 21a including a plurality of cores by a clad collective method. The optical fiber 21a has a configuration in which a plurality of cores are provided in a clad. The cladding batch method is a method in which pumping light is combined with an optical signal passing through each core in the optical fiber 21a by inputting the pumping light into the cladding.

In the third embodiment, the optical signals Lin1 to LinK are separately input to the optical fibers 911 to 91K, respectively. The first optical isolators 111 to 11 K respectively provided in the optical fibers 911 to 91 K restrict the propagation direction of the input optical signal to a fixed direction.

The optical signals Lin1 to LinK input to the K optical fibers 911 to 91K pass through the fiber bundle fan-out 87 to pass through the cores respectively present in one optical fiber 21a.

As described above, in a state where the optical signals Lin1 to LinK pass through one optical fiber 21a, the band monitor 3 is configured to transmit the entire band of the optical signals Lin1 to LinK passing through the optical fiber 21a (a band used for signal transmission ) And notify the light source drive circuit 61 of the band.

In addition, the first signal strength monitor 1 monitors the signal strength of the entire optical signals Lin1 to LinK passing through the optical fiber 21a, and notifies the gain control circuit 51 of the signal strength.

The subsequent operations of the gain control circuit 51, the light source drive circuit 61, the excitation light sources 31 to 3N, the output monitor 81, the switch control circuit 91, the N × 1 switch 71, and the optical multiplexer 41a are the gain control in the first embodiment. Operations of the circuit 51, the light source drive circuit 61, the excitation light sources 31 to 3N, the output monitor 81, the switch control circuit 91, the N × 1 switch 71, and the optical multiplexer 41 are the same. The switch control circuit 91 selects one excitation light source as in the first embodiment.

However, in the present embodiment, the optical multiplexer 41a combines the excitation light by the clad collective method with the optical signals passing through the cores in the optical fiber 21a.

Further, in this embodiment, in order to obtain sufficient excitation light output intensity, it is preferable to use excitation light sources of multi-mode output as the excitation light sources 31 to 3N, respectively. In this case, the N × 1 switch 71 is used together with a multi-mode output excitation light source. Further, the insertion loss of the N × 1 switch 71 is preferably small. Therefore, it is preferable that the N × 1 switch 71 be a mechanical control optical switch using, for example, a piezo actuator or the like.

Further, the second signal strength monitor 2 monitors the signal strength of the entire amplified optical signals Lout1 to LoutK passing through the optical fiber 21a, and notifies the gain control circuit 51 of the signal strength. The gain control circuit 51 confirms that the signal strength of the entire optical signal after amplification is a predetermined constant value based on the signal strength notified from the second signal strength monitor 2. If the signal intensity of the entire optical signal after amplification does not reach a predetermined constant value, the gain control circuit 51 adjusts the calculated gain. This point is the same as that of the first embodiment.

The optical signals Lout1 to LoutK amplified in the optical fiber 21a are branched from the one optical fiber 21a by passing through the fiber bundle fan-in 88, and pass through the respective separate optical fibers 921 to 92K. go.

According to the present embodiment, high power utilization efficiency can be realized as in the first embodiment. Furthermore, signal intensities can be amplified simultaneously for a plurality of optical signals.

Embodiment 4
FIG. 6 is a block diagram showing a configuration example of an optical fiber amplification system according to a fourth embodiment of the present invention. The optical fiber amplification system of the present embodiment comprises a plurality of the optical fiber amplifiers of the first embodiment of the present invention or the optical fiber amplifiers of the second embodiment of the present invention. Let the number of optical fiber amplifiers be K.

The optical fiber amplification system shown in FIG. 6 comprises a plurality of optical fiber amplifiers 10. Each optical fiber amplifier 10 is either the optical fiber amplifier according to the first embodiment of the present invention (see FIG. 1) or the optical fiber amplifier according to the second embodiment of the present invention (see FIG. 4). Good.

The optical fiber amplification system of the present embodiment includes an optical fiber 221 in addition to the plurality of optical fiber amplifiers 10. Hereinafter, the optical fiber 221 will be referred to as an external optical fiber 221 in distinction from the optical fibers 21 (see FIGS. 1 and 4) provided in each of the optical fiber amplifiers 10.

In addition, the optical fiber amplification system includes a first signal strength monitor 201, a second signal strength monitor 202, a gain control circuit 251, a light source drive circuit 261, and an optical multiplexer 241. Hereinafter, the first signal strength monitor 201, the second signal strength monitor 202, the gain control circuit 251, the light source drive circuit 261, and the optical multiplexer 241 are respectively provided in the respective optical fiber amplifiers 10 with similar elements and sections. The first external signal strength monitor 201, the second external signal strength monitor 202, the external gain control circuit 251, the external light source drive circuit 261, and the external light multiplexer 241 will be separately described. The optical fiber amplification system comprises one excitation light source 231 outside each optical fiber amplifier 10.

Further, the optical fiber amplification system comprises a fiber bundle fan-out 287, a fiber bundle fan-in 288, and a plurality of optical fibers 931 to 93 K connected upstream of the fiber bundle fan-out 287. The following description is given assuming that the number of optical fibers connected upstream of the fiber bundle fan-out 287 is K.

The external optical fiber 221 is one, and the external optical fiber 221 is a multi-core optical fiber including a plurality of cores. Hereinafter, the external optical fiber 221 will be described as including K cores.

The external optical fiber 221 is doped with rare earth ions (here, erbium ions). Here, it is assumed that erbium ions are added in the range from the position A 'to the position B' shown in FIG.

Further, in the present embodiment, a plurality of optical signals Lin1 to LinK are input. The input optical signals Lin1 to LinK are separately input to the optical fibers 931 to 93K. Each of the K optical fibers 931 to 93K includes one core.

In the external optical fiber 221, the first external signal strength monitor 201 is connected on the upstream side of the start position A 'of the addition range of erbium ions. Further upstream, a fiber bundle fan out 287 is provided. The fiber bundle fanout 287 connects the K optical fibers 931 to 93 K and the external optical fiber 221. Further, optical isolators 211, 212,..., 21K are individually connected to the K optical fibers 931 to 93K, respectively (see FIG. 6). Hereinafter, the optical isolators 221 to 21 K will be referred to as external optical isolators 211 to 21 K, separately from the first optical isolator 11 and the second optical isolator 12 provided in each optical fiber amplifier 10.

Also, a fiber bundle fan-in 288 is provided downstream of the second external signal strength monitor 202, and the fiber bundle fan-in 288 connects the external optical fiber 221 and the optical fiber 21 of each optical fiber amplifier 10 Ru. That is, the K cores in the external optical fiber 221 correspond to the cores in the optical fiber 21 in the K respective optical fiber amplifiers 10, and the corresponding cores are connected by the fiber bundle fan-in 288. It is connected.

As mentioned above, fiber bundle fan-out and fiber bundle fan-in are members of a common configuration. Specifically, one core included in each of the plurality of optical fibers and each core included in one optical fiber (here, the outer optical fiber 221) are paired with each other. It is a member to be connected to

The first external signal strength monitor 201 and the second external signal strength monitor 202 are connected to the external gain control circuit 251, respectively. Further, the external gain control circuit 251 is connected to the external light source drive circuit 261.

The external light source drive circuit 261 is connected to the excitation light source 231, and the excitation light source 231 is connected to the external light multiplexer 241.

The first external signal strength monitor 201 and the second external signal strength monitor 202 monitor the signal strength of the optical signal passing through the external optical fiber 221 and notify the external gain control circuit 251 of the signal strength. The external gain control circuit 251 calculates gains of the signal strengths of all the optical signals Lin1 to LinK and the signal strengths to be constant so that the signal strengths of all the optical signals after amplification become constant values. The external gain control circuit 251 notifies the external light source drive circuit 261 of the gain.

The external gain control circuit 251 and the external light source drive circuit 261 are each realized by, for example, a dedicated processor. Also, for example, the external gain control circuit 251 and the external light source drive circuit 261 may be realized by one processor having the function of each element.

An example of the operation in the sixth embodiment will be described.

First, the optical signals Lin1 to LinK are separately input to the optical fibers 931 to 93K. The external optical isolators 211 to 21 K provided in the respective optical fibers 931 to 93 K restrict the input optical signal propagation direction to a fixed direction.

The optical signals Lin1 to LinK separately input to the K optical fibers 931 to 93K pass through the fiber bundle fan-out 287 to pass through the respective cores present in one external optical fiber 221. .

As described above, in a state where the optical signals Lin1 to LinK pass through one external optical fiber 221, the first signal strength monitor 201 monitors the signal strength of the entire optical signals Lin1 to LinK, and performs external gain control. The circuit 251 is notified of the signal strength.

The external gain control circuit 251 calculates the gains of the signal strength notified from the first signal strength monitor 201 and the signal strength to be constant so that the signal strength of the entire optical signal after amplification becomes constant. Do. In other words, the external gain control circuit 251 calculates the gain when amplifying the signal strength of all the optical signals Lin1 to LinK to a predetermined signal strength. The external gain control circuit 251 stores in advance the value of the signal strength to be constant after amplification, and the external gain control circuit 251 determines the signal strength notified from the first signal strength monitor 201 and the signal strength thereof. It is sufficient to calculate the gain with

The external light source drive circuit 261 drives only the excitation light source 231. The external light source drive circuit 261 causes the excitation light source 231 to output excitation light at an excitation light output intensity corresponding to the gain notified from the external gain control circuit 251. The external light source drive circuit 261 increases the pumping light output intensity as the gain value increases, and decreases the pumping light output intensity as the gain value decreases.

The excitation light output from the excitation light source 231 is input to the external light multiplexer 241. The external optical multiplexer 241 combines the excitation light with the optical signals passing through the respective cores in the external optical fiber 221 by the clad collective method. That is, the external optical multiplexer 241 combines the excitation light into the respective optical signals Lin1 to LinK by inputting the excitation light to the cladding of the external optical fiber 221.

The signal intensity of each optical signal is amplified as each optical signal combined with the excitation light passes through the addition range of erbium ions in the external optical fiber 221.

In addition, the second external signal strength monitor 202 monitors the signal strength of the entire optical signal after amplification and notifies the external gain control circuit 251 of the signal strength. The external gain control circuit 251 confirms that the signal strength of each amplified optical signal is a predetermined constant by the signal strength notified from the second signal strength monitor 2. If the signal strength is not a predetermined constant value, the external gain control circuit 251 adjusts the calculated gain. This operation is similar to the operation of the gain control circuit 51 provided in each optical fiber amplifier 10.

Each optical signal amplified in the external optical fiber 221 is branched from one external optical fiber 221 by passing through the fiber bundle fan-in 288, and is input to K separate optical fiber amplifiers 10 respectively. Ru.

The individual optical signals branched by passing the fiber bundle fan-in 288 correspond to the optical signal Lin in the first embodiment or the second embodiment.

The operation of each optical fiber amplifier 10 to which the optical signal is input is similar to the operation of the optical fiber amplifier of the first embodiment or the optical fiber amplifier of the second embodiment.

Each optical fiber amplifier 10 comprises one optical fiber 21 (see FIGS. 1 and 4), and the optical fiber 21 includes one core. The optical multiplexer 41 (see FIG. 1 and FIG. 4) in the optical fiber amplifier 10 combines the excitation light into an optical signal by, for example, a core individual system.

The optical signals output from each of the K optical fiber amplifiers 10 are referred to as optical signals Lout1 to LoutK.

In the present embodiment, after the optical signals Lin1 to LinK are amplified by one external optical fiber 221, they are again amplified by K separate optical fiber amplifiers 10 and output as optical signals Lout1 to LoutK. .

The optical fiber amplification system of the present embodiment includes the optical fiber amplifier 10 of the first embodiment or the second embodiment. Therefore, the same effect as the first embodiment and the second embodiment can be obtained.

In the present embodiment, there is one excitation light source 231 that outputs excitation light to the external optical fiber 221. Then, variations in amplification of the optical signals Lin1 to LinK in the external optical fiber 221 may occur. However, each optical signal is then amplified again by the K optical fiber amplifiers 10 respectively. Therefore, the variation in amplification occurring in each optical signal in the external optical fiber 221 can be adjusted by the respective optical fiber amplifiers 10.

Embodiment 5
FIG. 7 is a block diagram showing a configuration example of an optical fiber amplifier according to a fifth embodiment of the present invention. A plurality of optical signals Lin1 to LinK are input to the optical fiber amplifier of the fifth embodiment, and the respective optical signals are output as optical signals Lout1 to LoutK after amplification. Each optical signal passes through a separate optical fiber.

In the fifth embodiment, the optical signals Lin1 to LinK are input to the optical fiber amplifier as a plurality of optical signals, and the optical fiber amplifier includes K optical fibers 271 to 27K as an example. explain.

Each of the optical fibers 271 to 27K includes one core.

Further, rare earth ions (here, erbium ions) are added to the optical fibers 271 to 27K. The doping range of erbium ions in the individual optical fibers is the same as the doping range of erbium ions in the optical fiber 21 in the first embodiment.

In the fifth embodiment, the optical fiber amplifier includes, for each optical fiber, a first optical isolator, a first signal intensity monitor, an optical multiplexer, a second signal intensity monitor, a second optical isolator, and a gain. It has a control circuit.

Therefore, the optical fiber amplifier comprises K first optical isolators 311 to 31 K, K first signal intensity monitors 811 to 81 K, K optical multiplexers 411 to 41 K, and K second Signal strength monitors 821 to 82K, K second optical isolators 321 to 32K, and K gain control circuits 511 to 51K.

The first optical isolators 311 to 31 K are all the same as the first optical isolator 11 in the first embodiment. The second optical isolators 321 to 32 K are all similar to the second optical isolator 12 in the first embodiment. The first signal strength monitors 811 to 81 K are all the same as the first signal strength monitor 1 in the first embodiment. The second signal strength monitors 821 to 82K are all the same as the second signal strength monitor 2 in the first embodiment. The optical multiplexers 411 to 41 K are all the same as the optical multiplexer 41 in the first embodiment. The gain control circuits 511 to 51K are all similar to the gain control circuit 51 in the first embodiment. The description of the above-described elements similar to those of the first embodiment is omitted.

In addition, the connection mode of the first optical isolator, the first signal intensity monitor, the optical multiplexer, the second signal intensity monitor, the second optical isolator, and the gain control circuit in each of the optical fibers 271 to 27 K is the first It is similar to the connection aspect of those elements in the embodiment of. For example, in the optical fiber 271, the first signal strength monitor 811 is connected upstream of the start position (not shown in FIG. 7) of the addition range of erbium ions, and the first optical isolator 311 is further upstream. It is connected. Further, in the optical fiber 271, the second signal intensity monitor 821 is connected downstream of the end position (not shown in FIG. 7) of the addition range of erbium ions, and the second optical isolator 321 is connected further downstream. It is done. The first signal strength monitor 811 and the second signal strength monitor 821 are connected to the gain control circuit 511, respectively. In addition, an optical coupler 411 is provided in the addition range of erbium ions in the optical fiber 271. Here, although the optical fiber 271 has been described as an example, the same applies to the other optical fibers 272 to 27K.

In the fifth embodiment, the optical fiber amplifier includes a band monitor 53, a light source drive circuit 561, a plurality (here, M) of excitation light sources 31 to 3M, an output monitor 581, and switch control. A circuit 591 and an M × K switch 571 are provided.

The band monitor 53 is connected between the first optical isolator and the first signal strength monitor in each of the optical fibers 271 to 27K. Further, the band monitor 53 is connected to the light source drive circuit 561. The gain control circuits 511 to 51 K are also connected to the light source drive circuit 561.

The excitation light sources 31 to 3 M are connected to the light source drive circuit 561. As in the first embodiment, the respective excitation light sources 31 to 3 M are excitation light sources having different excitation light output intensity versus power consumption characteristics. The excitation light output intensity versus power consumption characteristics of each of the excitation light sources 31 to 3 M may be changed, for example, by changing the maximum heat absorption amount of the Peltier cooler provided in each of the excitation light sources.

The M × K switch 571 is a switch having M input ends for excitation light and K output ends for excitation light. The input ends I1 to IM of the M × K switch 571 correspond to the excitation light sources 31 to 3M on a one-to-one basis, and the input ends I1 to IM are connected to the corresponding excitation light sources. Also, the output ends O1 to OK of the M × K switch 571 correspond to the optical fibers 271 to 27K on a one-to-one basis, and the output ends O1 to OK correspond to the optical couplers 411 to 41K provided in the corresponding optical fibers. It is connected. However, in the present embodiment, the magnitude relationship between M and K is K <M or K = M.

The output monitor 581 is connected to the light source drive circuit 561 and the switch control circuit 591. Further, the light source drive circuit 561 is connected to the switch control circuit 591. The switch control circuit 591 is connected to the M × K switch 571.

The band monitor 53 monitors the band of the optical signal passing through the optical fiber (the band used for signal transmission) for each of the optical fibers 271 to 27 K, and the band of the optical signal obtained for each of the optical fibers 271 to 27 K Each light source drive circuit 561 is notified.

Further, each of the gain control circuits 511 to 51 K notifies the light source drive circuit 561 of the calculated gains.

As a result, the light source drive circuit 561 obtains a set of gain and band for each optical fiber. Then, the light source drive circuit 561 calculates the product of the gain and the standby for each optical fiber. The light source drive circuit 561 selects one pumping light source to which pumping light is to be output for each optical fiber based on the product of the gain and the standby. Therefore, the light source drive circuit 561 selects K excitation light sources.

The method by which the light source drive circuit 561 selects one excitation light source for each individual optical fiber is the same as in the first embodiment. That is, the light source drive circuit 561 stores in advance the correspondence between the range (numerical range) of the product of the gain and the band and the excitation light source to be selected. For example, the light source drive circuit 561 stores in advance information indicating a correspondence relationship such that the excitation light source 31 corresponds to the range “0 or more and less than T1” and the excitation light source 32 corresponds to the range “T1 or more and less than T2”. ing.

For example, it is assumed that the product of the gain and the band obtained from the optical fiber 271 belongs to the range “0 or more and less than T1”. In this case, the light source drive circuit 561 selects the excitation light source 31 corresponding to the range “0 or more and less than T1” as the excitation light source that outputs the excitation light to the optical fiber 271. Also, for example, it is assumed that the product of the gain and the band obtained from the optical fiber 272 belongs to the range “T1 or more and less than T2”. In this case, the light source drive circuit 561 selects the excitation light source 32 corresponding to the range “T1 or more and less than T2” as the excitation light source for outputting the excitation light to the optical fiber 272.

The light source drive circuit 561 drives the respective selected excitation light sources, and causes the excitation light sources to output excitation light. At this time, the light source drive circuit 561 causes the excitation light source to output excitation light at an excitation light output intensity corresponding to the product of the gain and the band obtained from the optical fiber corresponding to the excitation light source. For example, it is assumed that the light source drive circuit 561 selects the excitation light source 31 as an excitation light source that outputs excitation light to the optical fiber 271. In this case, the light source drive circuit 561 causes the excitation light source 31 to output excitation light at an excitation light output intensity corresponding to the product of the gain and the band obtained from the optical fiber 271. The light source drive circuit 561 increases the pump light output intensity as the product of the gain and the band is larger, and lowers the pump light output intensity as the product of the gain and the band is smaller. The light source drive circuit 561 similarly drives other selected excitation light sources.

Furthermore, when the excitation light source is selected for each optical fiber, the light source drive circuit 561 selects the excitation light source, and the M × K switch corresponding to the input end of the M × K switch 71 corresponding to the excitation light source and the optical multiplexer provided in the optical fiber. The switch control circuit 591 is instructed to connect with the output end of 71. For example, as described above, it is assumed that the excitation light source 31 is selected as the excitation light source for outputting the excitation light to the optical fiber 271. In this case, the light source drive circuit 561 instructs the switch control circuit 591 to connect the input end I1 corresponding to the excitation light source 31 and the output end O1 corresponding to the optical multiplexer 411 provided in the optical fiber 271. . The light source drive circuit 561 instructs the switch control circuit 591 to connect the input end and the output end for K sets. The switch control circuit 591 connects the designated input end and the output end according to the instruction of the light source drive circuit 561.

The light source drive circuit 561 switches the excitation light source for outputting the excitation light according to the instruction of the output monitor 581 after selecting the excitation light source once for each of the optical fibers.

The output monitor 581 monitors the excitation light output intensity of the excitation light output from the light output end of the excitation light sources 31 to 3M. Specifically, the output monitor 581 monitors the excitation light output intensity of the excitation light output from the K excitation light sources driven by the light source drive circuit 561.

Further, the output monitor 581 stores the range of the excitation light output intensity which is determined in advance for each excitation light source. The output monitor 581 is, for example, a range “0 or more and less than R1 (see FIG. 2)” of excitation light output intensity determined for the excitation light source 31 and a range “R1 or more and less than R2 determined for the excitation light source 32 The range “R2 or more and less than R3 (see FIG. 2)” of the excitation light output intensity determined for the excitation light source 33 and the like are stored in advance. This point is the same as that of the first embodiment.

The light source drive circuit 561 outputs the excitation light to the optical fiber when the product of the gain and the band changes due to a change in one or both of the gain and the band obtained from the optical fiber for each optical fiber. The excitation light output intensity in the excitation light source is changed. The output monitor 581 outputs the excitation light output intensity of the excitation light output from any excitation light source outputting the excitation light at the boundary value of the range of the excitation light output intensity defined for the excitation light source. Then, the light source drive circuit 561 is instructed to switch the excitation light source for outputting the excitation light to the excitation light source corresponding to the adjacent range of the range. The light source drive circuit 561 switches the excitation light source for outputting the excitation light according to the instruction.

Further, the output monitor 581 causes the switch control circuit 591 to connect the output end to which the input end corresponding to the excitation light source before switching is connected to the input end corresponding to the excitation light source after switching. To direct. The switch control circuit 591 switches the connection between the input end and the output end of the M × K switch according to the instruction.

In the present embodiment, the gain control circuits 511 to 51K, the light source drive circuit 561, the output monitor 581, and the switch control circuit 591 are realized by, for example, dedicated processors. Further, the gain control circuits 511 to 51K, the light source drive circuit 561, the output monitor 581, and the switch control circuit 591 may be realized by one processor having the function of each element.

The optical fiber amplifier according to the fifth embodiment performs the same process on each of the input optical signals Lin1 to LinK. Hereinafter, an example of the operation of the fifth embodiment will be described by taking the optical signal Lin1 as an example. In addition, about the matter already demonstrated by 1st Embodiment, description is abbreviate | omitted suitably.

When the optical signal Lin1 is input to the optical fiber 271, the first optical isolator 311 limits the propagation direction of the optical signal to a certain direction.

The band monitor 53 monitors the band of the optical signal Lin1 passing through the optical fiber 271, and notifies the light source drive circuit 561 of the band.

In addition, the first signal strength monitor 811 monitors the signal strength of the optical signal Lin1, and notifies the gain control circuit 511 of the signal strength. The gain control circuit 511 is a gain between the signal strength of the optical signal Lin1 notified from the first signal strength monitor 811 and the signal strength to be constant so that the signal strength of the output optical signal Lout1 becomes constant. That is, the gain at the time of amplifying the signal strength of the optical signal Lin1 to a predetermined signal strength is calculated. The gain control circuit 511 notifies the light source drive circuit 561 of the calculated gain.

The light source drive circuit 561 calculates the product of the notified gain and the band, and selects the excitation light source that outputs the excitation light to the optical fiber 271 according to the product. Here, the light source drive circuit 561 selects the excitation light source 31 and demonstrates.

The light source drive circuit 561 is connected to connect the input end I1 of the M × K switch 571 corresponding to the excitation light source 31 and the output end O1 corresponding to the optical coupler 411 provided in the optical fiber 271. The control circuit 591 is instructed. The switch control circuit 591 connects the input end I1 and the output end O1 according to the instruction.

Further, the light source drive circuit 561 causes the excitation light source 31 to output excitation light at the excitation light output intensity corresponding to the product of the gain and the band. The excitation light is input to the input end I1 of the M × K switch 571 and output from the output end O1. The optical multiplexer 411 combines the excitation light into the optical signal Lin1. As a result, the signal strength of the light signal Lin1 is amplified to a constant signal strength and is output as the light signal Lout1.

At this time, the second signal strength monitor 821 monitors the signal strength of the optical signal Lout1, and notifies the gain control circuit 511 of the signal strength. The gain control circuit 511 confirms that the signal strength of the optical signal Lout1 has a predetermined constant value based on the signal strength notified from the second signal strength monitor 821. If the signal strength of the optical signal Lout does not reach a predetermined constant value, the gain control circuit 511 adjusts the calculated gain thereafter.

The second optical isolator 321 restricts the propagation direction of the optical signal Lout1 to a fixed direction.

The optical fiber amplifier performs the same processing on other input optical signals Lin2 to LinK. As a result, the input optical signals Lin1 to LinK are respectively amplified.

In addition, the output monitor 581 is a boundary of the range of the excitation light output intensity in which the excitation light output intensity of the excitation light output from any excitation light source outputting the excitation light is determined for the excitation light source When it reaches the value, the light source drive circuit 561 is instructed to switch the excitation light source for outputting the excitation light to the excitation light source corresponding to the adjacent range of the range. The light source drive circuit 561 switches the excitation light source for outputting the excitation light according to the instruction. For example, it is assumed that the excitation light output intensity of the excitation light output from the excitation light source 31 becomes R1 (see FIG. 2). Here, in the M × K switch 571, it is assumed that the input end I1 and the output end O1 are connected. The output monitor 581 switches the excitation light source for outputting the excitation light from the excitation light source 31 to the excitation light source 32 based on the fact that the excitation light output intensity of the excitation light output from the excitation light source 31 becomes R1. The driver circuit 561 is instructed. The light source drive circuit 561 switches the excitation light source that outputs excitation light from the excitation light source 31 to the excitation light source 32.

The output monitor 581 instructs the switch control circuit 591 to connect the output end O1 to the input end I2 corresponding to the excitation light source 32 after switching. In accordance with the instruction, the switch control circuit 591 disconnects the input end I1 from the output end O1 and connects the input end I2 of the M × K switch 571 to the output end O1. As a result, the pumping light output from the pumping light source 32 is combined with the optical signal Lin1 by the optical multiplexer 411, and the signal intensity of the optical signal Lin1 is amplified.

In the above description, switching of the excitation light source for outputting excitation light to the optical fiber 271 has been described as an example. The operations of the output monitor 581, the light source drive circuit 561 and the switch control circuit 591 in the case of switching the excitation light source for outputting the excitation light to another optical fiber are similar to the above.

Also in this embodiment, the same effect as that of the first embodiment can be obtained.

Furthermore, according to the present embodiment, it is possible to individually amplify the signal strengths of the plurality of optical signals Lin1 to LinK.

Furthermore, the optical fiber amplifier of the present embodiment includes an M × K switch 571. Therefore, an increase in the number of excitation light sources can be prevented. For example, when the N × 1 switch in the first embodiment is used, N pumping light sources are required for each optical fiber, so if the number of optical fibers is K, N × K excitation light sources are required. In this embodiment, since the M × K switch 571 is used, it is sufficient to provide M excitation light sources for K optical fibers if K <M or K = M is satisfied. It can prevent the increase of the number.

In each of the above embodiments, the optical multiplexer is disposed upstream of the erbium ion doping range of the optical fiber, and the case where the optical signal and the excitation light propagate in the same direction in the optical fiber is taken as an example. Explained. The aspect which amplifies the signal strength of an optical signal in such an aspect is called forward pumping.

In each embodiment of the present invention, the optical multiplexer is disposed downstream in the erbium ion doping range of the optical fiber, and the propagation direction of the optical signal and the propagation direction of the excitation light in the optical fiber are opposite to each other An optical multiplexer may input excitation light to an optical fiber so that The aspect which amplifies the signal strength of an optical signal in such an aspect is called backward pumping. In each embodiment of the present invention, backward excitation may be employed.

Further, in each embodiment, the case where the optical multiplexer is provided in the addition range of erbium ions in the optical fiber has been described as an example. In each of the above embodiments, an optical multiplexer may be provided outside the doped range of erbium ions in the optical fiber. For example, in the case of adopting forward pumping, an optical multiplexer may be provided upstream of the start position (for example, position A illustrated in FIG. 1) of the addition range of erbium ions in the optical fiber. Also, for example, in the case of employing backward pumping, an optical multiplexer may be provided downstream of the end position (for example, position B illustrated in FIG. 1) of the addition range of erbium ions in the optical fiber.

In addition, the optical isolators shown in the above embodiments are provided for the purpose of preventing the oscillation of the optical fiber amplifier caused by the multiple reflection of the optical signal. In each of the above-described embodiments, if a long optical fiber is used as the optical fiber to maintain a high return loss, the optical isolator may not be provided.

Next, an outline of the present invention will be described. FIG. 8 is a block diagram showing an outline of the present invention. The optical fiber amplifier of the present invention comprises an optical fiber 1021, a plurality of light sources 1031 to 103N, a light source driving means 1061, a combining means 1041, and a switch 1071.

The optical fiber 1021 (for example, the optical fiber 21, the optical fiber 21a, the optical fibers 271 to 27K, etc.) passes an optical signal and amplifies the signal intensity of the optical signal when the excitation light is combined with the optical signal. It is an optical fiber.

The light sources 1031 to 103N (for example, excitation light sources 31 to 3N, excitation light sources 31 to 3M, etc.) are a plurality of light sources that output excitation light, and are a plurality of light sources having different excitation light output intensity versus power consumption characteristics. .

The light source driving unit 1061 (for example, the light source driving circuit 61, the light source driving circuit 561, and the like) causes the light source to output excitation light.

The combining means 1041 (for example, the optical multiplexer 41, the optical multiplexer 41a, the optical multiplexers 411 to 41K, etc.) combines the excitation light output from the light source into an optical signal.

The switch 1071 (for example, the N × 1 switch 71, the M × K switch 571, etc.) has an input end of excitation light corresponding to each light source, and an output for outputting the excitation light to the combining means 1041 Have an end.

With such a configuration, high power utilization efficiency can be realized.

Although each embodiment of the above-mentioned present invention may be described as the following supplementary notes, it is not necessarily limited to the following.

(Supplementary Note 1)
An optical fiber for passing an optical signal and amplifying the signal intensity of the optical signal when excitation light is combined with the optical signal;
A plurality of light sources for outputting the excitation light, the plurality of light sources each having different excitation light output intensity versus power consumption characteristics;
Light source driving means for outputting excitation light from the light source;
Combining means for combining excitation light output from the light source with the optical signal;
An optical fiber amplifier comprising an input end of excitation light corresponding to each light source and a switch having an output end for outputting the excitation light to the combining means for each individual light source.

(Supplementary Note 2)
Switch control means for controlling an input end connected to the output end in the switch;
The light source driving means monitors the excitation light output intensity of the excitation light output from the light source, and when the excitation light output intensity becomes a boundary value of the range of the excitation light output intensity defined for the light source, And switching instruction means for instructing switching of the light source for outputting the excitation light and instructing the switch control means to connect the input end corresponding to the switched light source to the output end. Optical fiber amplifier.

(Supplementary Note 3)
The optical fiber amplifier according to

Appendix

1 or 2, wherein the plurality of light sources each include a Peltier cooler, and the maximum heat absorption amount of the individual Peltier coolers corresponding to the individual light sources is different.

(Supplementary Note 4)
Gain calculating means for calculating gains of the signal strength of the optical signal input to the optical fiber and the predetermined signal strength;
And band monitor means for monitoring a band used for signal transmission in the optical signal input to the optical fiber,
The light source driving means selects a light source for outputting excitation light based on at least the band, and outputs excitation light at an excitation light output intensity corresponding to a product of the gain and the band from the light source. 4. An optical fiber amplifier according to any of the preceding claims.

(Supplementary Note 5)
Gain calculating means for calculating gains of the signal strength of the optical signal input to the optical fiber and the predetermined signal strength;
And band monitor means for monitoring a band used for signal transmission in the optical signal input to the optical fiber,
The light source driving means selects a light source for outputting pumping light based on the product of the gain and the band, and the pumping light is output from the light source at a pumping light output intensity corresponding to the product of the gain and the band. The optical fiber amplifier according to any one of Appendixes 1 to 4.

(Supplementary Note 6)
Equipped with one optical fiber with one core,
The optical fiber amplifier according to Appendix 4 or 5, wherein the light source driving means selects one light source for outputting the excitation light.

(Appendix 7)
The optical fiber amplifier according to claim 6, wherein the combining means combines the excitation light into the optical signal by a core individual system.

(Supplementary Note 8)
One fiber with multiple cores,
The optical fiber amplifier according to Appendix 4 or 5, wherein the light source driving means selects one light source for outputting the excitation light.

(Appendix 9)
The optical fiber amplifier according to claim 8, wherein the combining means combines the excitation light into the optical signal by a clad collective method.

(Supplementary Note 10)
With multiple optical fibers with one core,
Each optical fiber has a combining means,
The switch has an output end corresponding to the combining means for each individual combining means,
The optical fiber amplifier according to Appendix 4 or 5, wherein the light source driving means selects one light source for outputting the excitation light for each optical fiber.

(Supplementary Note 11)
The optical fiber amplifier according to any one of Appendixes 1 to 10, wherein the optical fiber is an optical fiber doped with rare earth ions.

(Supplementary Note 12)
A plurality of optical fiber amplifiers according to Appendix 6 or Appendix 7,
Comprising a plurality of cores corresponding to the cores in the optical fibers in each of the optical fiber amplifiers, and one external optical fiber provided outside the plurality of optical fiber amplifiers,
An optical fiber amplification system comprising one external light source for outputting excitation light to the external optical fiber.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. The configurations and details of the present invention can be modified in various ways that those skilled in the art can understand within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2017-126622 filed on June 28, 2017, the entire disclosure of which is incorporated herein.

Industrial Applicability

The present invention is preferably applied to an optical fiber amplifier and an optical fiber amplification system that amplifies the signal strength of an optical signal.

DESCRIPTION OF SYMBOLS 1 1st signal strength monitor 2 2nd signal strength monitor 3 band monitor 11 1st optical isolator 12 2nd optical isolator 21 optical fiber 31-3N excitation light source 41 optical multiplexer 51 gain control circuit 61 light source drive circuit 71 Switch 81 Output monitor 91 Switch control circuit

Claims

An optical fiber for passing an optical signal and amplifying the signal intensity of the optical signal when excitation light is combined with the optical signal;
A plurality of light sources for outputting the excitation light, the plurality of light sources each having different excitation light output intensity versus power consumption characteristics;
Light source driving means for outputting excitation light from the light source;
Combining means for combining excitation light output from the light source with the optical signal;
An optical fiber amplifier comprising an input end of excitation light corresponding to each light source and a switch having an output end for outputting the excitation light to the combining means for each individual light source.
Switch control means for controlling an input end connected to the output end in the switch;
The light source driving means monitors the excitation light output intensity of the excitation light output from the light source, and when the excitation light output intensity becomes a boundary value of the range of the excitation light output intensity defined for the light source, And a switching instruction unit that instructs the switch control unit to connect the input end corresponding to the switched light source to the output end. Optical fiber amplifier.
The optical fiber amplifier according to claim 1 or 2, wherein the plurality of light sources each include a Peltier cooler, and the maximum heat absorption amount of the individual Peltier coolers corresponding to the individual light sources is different.
Gain calculating means for calculating gains of the signal strength of the optical signal input to the optical fiber and the predetermined signal strength;
And band monitor means for monitoring a band used for signal transmission in the optical signal input to the optical fiber,
The light source driving means selects a light source for outputting pumping light based on at least the band, and outputs the pumping light with a pumping light output intensity corresponding to the product of the gain and the band from the light source. The optical fiber amplifier according to any one of claims 1 to 3.
Gain calculating means for calculating gains of the signal strength of the optical signal input to the optical fiber and the predetermined signal strength;
And band monitor means for monitoring a band used for signal transmission in the optical signal input to the optical fiber,
The light source driving means selects a light source for outputting pumping light based on the product of the gain and the band, and the pumping light is output from the light source at a pumping light output intensity corresponding to the product of the gain and the band. The optical fiber amplifier according to any one of claims 1 to 4.
Equipped with one optical fiber with one core,
The optical fiber amplifier according to claim 4 or 5, wherein the light source driving means selects one light source for outputting the excitation light.
The optical fiber amplifier according to claim 6, wherein the combining means combines the excitation light into the optical signal by a core individual system.
One fiber with multiple cores,
The optical fiber amplifier according to claim 4 or 5, wherein the light source driving means selects one light source for outputting the excitation light.
The optical fiber amplifier according to claim 8, wherein the combining means combines the excitation light into the optical signal by a clad collective method.
With multiple optical fibers with one core,
Each optical fiber has a combining means,
The switch has an output end corresponding to the combining means for each individual combining means,
The optical fiber amplifier according to claim 4 or 5, wherein the light source driving means selects one light source for outputting the excitation light for each optical fiber.
The optical fiber amplifier according to any one of claims 1 to 10, wherein the optical fiber is an optical fiber doped with rare earth ions.
A plurality of optical fiber amplifiers according to claim 6 or claim 7,
Comprising a plurality of cores corresponding to the cores in the optical fibers in each of the optical fiber amplifiers, and one external optical fiber provided outside the plurality of optical fiber amplifiers,
An optical fiber amplification system comprising one external light source for outputting excitation light to the external optical fiber.