JP6891957B2 - Fiber optic amplifier and fiber optic amplification system - Google Patents

Description

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

An example of an optical fiber amplifier that amplifies the signal intensity of an optical signal is described in Patent Document 1. Patent Document 1 describes a configuration in which the signal intensity of an optical signal is amplified by inputting excitation light output from an excitation light source into a rare earth-added fiber into which an optical signal is input. Patent Document 2 also describes a similar configuration.

Such an optical fiber amplifier is used as an amplifier for optical signal relay in an optical fiber communication system because it has high efficiency and high gain and the gain is almost polarization-independent.

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

Japanese Unexamined Patent Publication No. 11-12434 Japanese Unexamined Patent Publication No. 9-116506 Japanese Unexamined Patent Publication 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, a case where erbium ions are added to the optical fiber 121 will be described as an example. Here, it is assumed that the erbium ion is added to the range from the position A to the position B shown in FIG. As shown in FIG. 9, the optical fiber 121 includes a first optical isolator 171, a first signal intensity monitor 101, an optical combiner 141, a second signal intensity monitor 102, and a second optical isolator. 172 and 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.

An optical signal Lin is input to the optical fiber 121, and an optical signal Lout after signal intensity amplification is output. The first optical isolator 171 and the second optical isolator 172 limit the propagation direction of the optical signal to 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 the gain between 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 is at a predetermined constant value by 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 to output the excitation light from the excitation light source 131 with the excitation light output intensity corresponding to the gain.

The optical combiner 141 synthesizes the excitation light output from the excitation light source 131 into the optical signal Lin. In the optical fiber 121 to which the erbium ion is added, the excitation light is synthesized with the optical signal Lin, so that the signal intensity of the optical signal Lin is amplified and the optical signal Lout after the signal intensity amplification is output.

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

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

Then, in order to operate the optical fiber amplifier efficiently over a long period of time, the "band used for signal transmission" is narrowed at the initial stage of operation, and as the traffic increases, the "band used for signal transmission" is performed by wavelength multiplexing. Is taken. In this way, the "bandwidth used for signal transmission" changes as the traffic increases after the start of operation. The "band used for signal transmission" can also be referred to as a spectrum, a WDM (Wavelength Division Multiplexing) signal usage rate, or a wavelength packing factor. Hereinafter, the "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. The excitation light source 131 is designed according to the maximum band of the optical signal. That is, the excitation light source 131 is designed so that the excitation light having a high excitation light output intensity can be output when the "band used for signal transmission" becomes wide. FIG. 10 is a schematic diagram showing the excitation light output intensity vs. power consumption characteristics of such an excitation light source 131. The horizontal axis shown in FIG. 10 is the excitation light output intensity of the excitation light source. It can be said that the excitation light output intensity is almost 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, the excitation light source 131 designed to output excitation light with high excitation light output intensity when the "band used for signal transmission" becomes wide, consumes power even when the band is narrow. It doesn't drop that much. Then, for example, in a state where the band is narrowed, such as after the start of operation, the power consumption becomes large.

As shown by the broken line in FIG. 10, it is preferable that the power consumption is 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.

Further, when the power consumption is prioritized and the power consumption is designed to be small in a state where the band is narrowed, the excitation light having a high excitation light output intensity cannot be output when the band is widened.

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 amplifies the signal intensity of an optical signal when an optical signal is passed and excitation light is synthesized with the optical signal, and a plurality of light sources that output excitation light. , Multiple light sources with different excitation light output intensity vs. power consumption characteristics, light source driving means for outputting excitation light from the light source, synthesis means for synthesizing excitation light output from the light source into an optical signal, and each individual light source From the light source, a switch having an input end of excitation light corresponding to the light source and having an output end for outputting the excitation light to the synthesis means, a switch control means for controlling the input end connected to the output end in the switch, and the light source. When the excitation light output intensity of the output excitation light is monitored and the excitation light output intensity reaches the boundary value within the range of the excitation light output intensity defined for the light source, the light source driving means is used. The switch control means is provided with a switching instruction means for instructing the switching of the light source for outputting the excitation light and for instructing the switch control means to connect the input end corresponding to the light source after the switching to the output end .

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

It is a block diagram which shows the structural example of the optical fiber amplifier of 1st Embodiment of this invention. It is a schematic diagram which shows the excitation light output intensity vs. power consumption characteristic of a plurality of excitation light sources. It is a schematic diagram which shows the difference of the power consumption between the 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 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 which shows the outline of this invention. It is a schematic diagram which shows the example of the general optical fiber amplifier. It is a schematic diagram which shows the excitation light output intensity vs. power consumption characteristic of the excitation light source provided in a general optical fiber amplifier.

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

Similar to the above case, in each embodiment, the "band used for signal transmission" may be simply referred to as a band. As described above, the "band used for signal transmission" can also be referred to as spectrum, WDM signal utilization, or wavelength packing factor.

Embodiment 1.
FIG. 1 is a block diagram showing a configuration example of an optical fiber amplifier according to the first embodiment of the present invention. The optical fiber amplifier of the first embodiment includes a first signal strength monitor 1, a second signal strength monitor 2, a band monitor 3, a first optical isolator 11, a second optical isolator 12, and the like. It includes an optical fiber 21, a plurality of excitation light sources 31 to 3N, an optical combiner 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 to which rare earth ions are added. Here, a case where erbium ions are added to the optical fiber 21 will be described as an example. Further, it is assumed that the erbium ion is added to the range from the position A to the position B shown in FIG.

Further, the optical fiber amplifier of the first embodiment includes one optical fiber 21. In this embodiment, the optical fiber 21 includes one core.

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

That is, the optical fiber 21 is an optical fiber that amplifies the signal intensity of the optical signal when the optical signal is passed through and the excitation light is synthesized with the optical signal.

In the example shown in FIG. 1, the optical signal input to the optical fiber 21 is referred to as Lin. Further, the amplified optical signal output from the optical fiber is referred to as Lout. Further, for convenience, in the optical fiber 21, the side where the optical signal Lin is input is referred to as the upstream side, and the side where 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 to the upstream side of the start position A of the erbium ion addition range, and the first optical isolator 11 is further connected to the upstream side. Further, in the optical fiber 21, the second signal intensity monitor 2 is connected to the downstream side of the end position B of the erbium ion addition range, and the second optical isolator is further connected to the downstream side.

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

Further, 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.

Each excitation light source 31 to 3N is connected to the light source drive circuit 61.

The switch 71 is provided with an excitation light input terminal corresponding to the excitation light source for each excitation light source. In the example shown in FIG. 1, the switch 71 includes input terminals 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 input ends of the switch 71 also correspond to one excitation light source.

The light output ends of each of the 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.

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

Further, the light output ends 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, each element will be described.

Each of the excitation light sources 31 to 3N is an excitation light source having different excitation light output intensity vs. power consumption characteristics. FIG. 2 is a schematic diagram showing the excitation light output intensity vs. 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. It can be said that the excitation light output intensity is almost proportional to the "band used for signal transmission". This is because, 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 smaller 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, and 35 are preferable in this order. However, the excitation light source 31 can output excitation light up to the excitation light output intensity R1, but cannot output excitation light having an excitation light output intensity higher than that. Similarly, the upper limits of the excitation light output intensity of the excitation light that can be output by the excitation light sources 32, 33, and 34 are R2, R3, and R4, respectively.

For example, when outputting the excitation light having the excitation light output intensity a (see FIG. 2), it is preferable to output the excitation light from the excitation light source 31 having the lowest power consumption. Further, when the excitation light having the excitation light output intensity b (see FIG. 2) is output, the excitation light source 31 cannot be used because R1 <b. In this case, it is preferable to output the excitation light from the excitation light source 32 having the lowest power consumption 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 a plurality of excitation light sources having different excitation light output intensity vs. power consumption characteristics.

Further, each of the excitation light sources 31 to 3N is provided with a Pertier cooler. The maximum heat absorption of each Pertier cooler corresponding to each excitation light source is different. By making the maximum heat absorption amount of the Pertier cooler provided in the excitation light source different in this way, the excitation light output intensity vs. power consumption characteristics of each excitation light source 31 to 3N can be changed. However, not only the maximum heat absorption amount of the Pertier cooler but also other factors may be changed to change the excitation light output intensity vs. power consumption characteristics of each excitation light source 31 to 3N.

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

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

The first optical isolator 11 and the second optical isolator 12 limit the propagation direction of the optical signal to a certain 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. Is calculated. In other words, the gain control circuit 51 calculates the gain when amplifying the signal strength of the optical signal Lin to a predetermined signal strength in the optical fiber 21. 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 between 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 output 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 is at a predetermined constant value by the signal strength notified from the second signal strength monitor 2. If the signal intensity of the optical signal Lout is not a predetermined constant value, the gain control circuit 51 adjusts the calculated gain. For example, assume that the signal strength of the optical signal Lout should be constant at 100. If the signal intensity of the actual optical signal Lout notified from the second signal intensity monitor 2 is greater than 100, the gain control circuit 51 adjusts so as to reduce the calculated gain value. Further, if the signal intensity of the actual optical signal Lout notified from the second signal intensity monitor 2 is less than 100, the gain control circuit 51 adjusts so as to increase the calculated gain value.

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

The band monitor 3 monitors the band (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, the light source drive circuit 61 selects one of the plurality of excitation light sources 31 to 3N to output the excitation light based on the product of the gain and the band.

The light source drive circuit 61 stores in advance the correspondence between the product range (numerical range) of the gain and the band and the selected excitation light source. The light source drive circuit 61 stores in advance information indicating a correspondence relationship, for example, the range “0 or more and less than T1” corresponds to the excitation light source 31, and the range “T1 or more and less than T2” corresponds to the excitation light source 32. ing. Here, each range is defined so as not to overlap and to be continuous across a boundary. Further, the smaller the value range, 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 outputs the excitation light from the excitation light source with the excitation light output intensity corresponding to the product of the gain and the band. In the light source drive circuit 61, the larger the value of the product of the gain and the band, the higher the excitation light output intensity, and the smaller the value of the product of the gain and the band, the lower the excitation light output intensity.

The light source drive circuit 61 once selects one excitation light source based on the product of the gain and the band, and then switches the excitation light source to output the excitation light according to the instruction of the output monitor 81.

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. When a gain and a band are newly notified, the light source drive circuit 61 changes the excitation light output intensity of the excitation light from the excitation light source that outputs the excitation light according to the product of the gain and the band. As described above, the light source drive circuit 61 once selects one excitation light source based on the product of the gain and the band, and then switches the excitation light source to output the excitation light according to the instruction of the output monitor 81. 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 that outputs the excitation light.

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

It is assumed that the product of the gain and the band changes due to a change in 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 that outputs the excitation light according to the product after the change. When the excitation light output intensity of the excitation light output from the excitation light source driven by the light source drive circuit 61 becomes the boundary value in 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 range adjacent to 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 excitation light source after switching and the output end O1 of the switch 71.

The light source drive circuit 61 switches the excitation light source to output 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 excitation light source after switching 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, a switch 71 having 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 with respect to excitation light in the 0.98 μm band, excitation light in the 1.48 μm band, or both, and has a maximum insertion loss of 1 dB or less.

The optical combiner 41 synthesizes the excitation light output from the output terminal O1 of the N × 1 switch 71 into the optical signal Lin.

Each of the individual excitation light sources 31 to 3N is 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 dedicated sensors.

Further, the gain control circuit 51, the light source drive circuit 61, the output monitor 81, and the switch control circuit 91 are realized by, for example, dedicated processors. 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 functions of the respective elements.

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

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

The band monitor 3 monitors the band (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, in the initial stage of operation of the optical fiber amplifier, the traffic (communication amount) by the optical signal is small, and the value of the band monitored by the band monitor 3 is also a small value.

Further, 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 when 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 between 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.

As the operating time elapses, the traffic tends to increase, and the band of the optical signal Lin (the band used for signal transmission) tends to increase. Further, 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 range “0 or more and less than T1” corresponds to the excitation light source 31, and the range “T1 or more and less than T2” corresponds to the excitation light source 32. The information to be shown is stored in advance. Further, the smaller the value range, the smaller the power consumption is associated with the excitation light source. The light source drive circuit 61 selects one of a plurality of excitation light sources 31 to 3N as an excitation light source corresponding to the range to which the calculated product belongs.

Here, it is assumed that the optical fiber amplifier is in the initial state of the start of operation, and the value of the band of the input optical signal Lin is a small value. Then, it is assumed that 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 to output the excitation light from the excitation light source 31 with the excitation light output intensity corresponding to the product of the gain and the band. As described above, in the light source drive circuit 61, the larger the value of the product of the gain and the band, the higher the excitation light output intensity, and the smaller the value of the product of the gain and the band, the lower the excitation light output intensity. To do.

Here, the excitation light source 31 selected by the light source drive circuit 61 has the highest efficiency of the excitation light output intensity vs. power consumption characteristic when outputting the excitation light of the excitation light output intensity corresponding to the product of the gain and the band. It is an excitation light source. As described above, it is preferable that the power consumption is proportional to the excitation light output intensity. 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 shown by a broken line in FIG. Under the specified excitation light output intensity, the excitation light source with the highest efficiency of excitation light output intensity vs. power consumption characteristic is the coordinate represented by (specified excitation light output intensity, power consumption). It is the excitation light source closest to the straight line.

For example, it is assumed that the value of the excitation light output intensity according to the product of the gain and the band is “a” shown in FIG. When the excitation light having 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 determined for each excitation light source (a, power consumption), the coordinates corresponding to the excitation light source 31 (a, power consumption) are closest to the straight line 19. Therefore, when the value of the product of the gain and the band is small and the excitation light output intensity is also small, the excitation light output intensity vs. power consumption characteristic of the excitation light source 31 becomes the most efficient.

In the initial stage of operation, the input terminal I1 and the output terminal O1 may be connected in the N × 1 switch 71 based on the fact that the traffic due to the optical signal is small. Alternatively, when the light source drive circuit 61 selects an excitation light source based on the product of the gain and the band, the light source drive circuit 61 connects the input end and the output end O1 corresponding to the excitation light source to the switch control circuit 91. The switch control circuit 91 may connect the instructed input end and the output end O1 in accordance with 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 having an excitation light output intensity determined by the light source drive circuit 61. The excitation light is input to the input terminal I1 corresponding to the excitation light source 31 at the N × 1 switch 71, and the N × 1 switch 71 outputs the excitation light input to the input terminal I1 from the output terminal 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 terminal is output from the output terminal O1.

The optical combiner 41 synthesizes the excitation light output from the output terminal O1 of the N × 1 switch 71 into the optical signal Lin.

The mode in which the optical combiner 41 synthesizes the excitation light into the optical signal may be a core individual method or another method. The core individual method is a method in which excitation light is synthesized into an optical signal passing through the core by inputting excitation light to the core in the optical fiber 21. Alternatively, the optical combiner 41 may synthesize the excitation light with the optical signal passing through the core by inputting the excitation light into the cladding existing 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. Excitation light having an excitation light output intensity corresponding to the product of the band of the optical signal Lin and the gain calculated by the gain control circuit 51 is synthesized in the optical signal Lin. As a result, the signal strength of the optical signal Lin is amplified to a constant signal strength and output as an optical 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 is at a predetermined constant value by the signal strength notified from the second signal strength monitor 2. If the signal intensity of the optical signal Lout is not a predetermined constant value, the gain control circuit 51 subsequently adjusts the calculated gain.

Further, the second optical isolator 12 limits the propagation direction of the optical signal to a certain 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 that outputs 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 ends of each excitation light source 31 to 3N. Then, when the excitation light output intensity of the excitation light of the excitation light source outputting the excitation light reaches the boundary value in the range of the excitation light output intensity defined for the excitation light source, the output monitor 81 determines. The light source drive circuit 61 is instructed to switch the excitation light source that outputs the excitation light to the excitation light source corresponding to the range of the adjacent excitation light output intensity via the boundary value thereof. 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 excitation light source after switching 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 excitation light source after switching and the output end O1 of the switch 71 according to the instruction.

Hereinafter, an example of switching 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 the gain and the band increases, the light source drive circuit 61 increases the excitation light output intensity of the excitation light output to the excitation light source 31, and the excitation light output intensity reaches the boundary value R1 (see FIG. 2). Suppose it becomes. Then, from the range of the excitation light output intensity defined for the excitation light source 31 "0 or more and less than R1 (see FIG. 2)", the adjacent range via the boundary value R1 is "R1 or more and less than R2 (see FIG. 2)". ", And this 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 that outputs the excitation light from the excitation light source 31 to the excitation light source 32, and the light source drive circuit 61 sets the excitation light source that 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 terminal I2 of the switch 71 corresponding to the excitation light source 32 after switching and the output terminal O1 of the switch 71, and controls the switch. The circuit 91 connects the input terminal I2 and the output terminal O1.

As a result, when the product of the gain and the band increases and 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 combined with the optical signal Lin by the optical combiner 41.

In the above example, an example in which the excitation light output intensity is increased is shown, but the switching of the excitation light source in the case of decreasing the excitation light output intensity is also the same. For example, it is assumed that the excitation light source 32 outputs the excitation light source. Then, it is assumed that the excitation light output intensity reaches the boundary value R1 (see FIG. 2) due to the decrease in the product of the gain and the band. From the range of excitation light output intensity defined for the excitation light source 32, "R1 or more and less than R2 (see FIG. 2)", the adjacent range via the boundary value R1 is "0 or more and less than R1 (see FIG. 2)". Yes, 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 that outputs the excitation light from the excitation light source 32 to the excitation light source 31, and the light source drive circuit 61 sets the excitation light source that 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 terminal I1 of the switch 71 corresponding to the excitation light source 31 after switching and the output terminal O1 of the switch 71, and controls the switch. The circuit 91 connects the input end I1 and the output end O1.

As a result, when the product of the gain and the band decreases and 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 combined with the optical signal Lin by the optical combiner 41.

As the mode in which the product of the gain and the band changes, the product changes by changing only the band, the product changes by changing only the gain, and both the gain and the band change. There is an aspect in which the product changes. Any of these modes may be used in which the product of the gain and the band changes.

According to the present embodiment, the optical fiber amplifier includes a plurality of excitation light sources having different excitation light output intensity vs. power consumption characteristics. Then, the light source drive circuit 61 selects one excitation light source based on the product of the gain notified from the gain control circuit 51 and the band notified from 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 having the highest efficiency of the excitation light output intensity vs. the power consumption characteristic. Therefore, high power utilization efficiency can be realized.

Further, the light source drive circuit 61 outputs the excitation light from the excitation light source with the excitation light output intensity corresponding to the above product. When the product of the gain and the band changes and the excitation light output intensity reaches the boundary value in the range of the excitation light output intensity defined for the excitation light source, the output monitor 81 instructs the light source drive circuit 61 to switch the excitation light source. .. Further, the output monitor 81 instructs the switch control circuit 91 to connect the input terminal I1 of the switch 71 corresponding to the excitation light source 31 after switching and the output terminal O1 of the switch 71. Therefore, even if the excitation light output intensity changes according to the change in the product of the gain and the band, the optical fiber amplifier outputs the excitation light from the excitation light source having the highest efficiency of the excitation light output intensity vs. power consumption characteristic. be able to. In this respect as well, high power utilization efficiency can be realized.

FIG. 3 is a schematic diagram 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 vertical axis on the left shows traffic. As traffic increases, so does the bandwidth used for signal transduction. The vertical axis on the right side shows power consumption. The solid line graph shown in FIG. 3 shows the change 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, a temporary increase in traffic due to a disaster or the like may occur. The alternate long and short dash line graph shown in FIG. 3 schematically shows the change in power consumption in a general optical fiber amplifier (see FIG. 9) in response to the change in traffic shown in FIG. The broken line graph shown in FIG. 3 schematically shows the change in power consumption of the present invention in response to the change in traffic shown in FIG. The power consumption of the present invention is lower than that of the general optical fiber amplifier shown in FIG. 9, and according to the present invention, high power utilization efficiency can be realized.

Next, a modified example of the first embodiment will be described. The modifications shown below can be applied 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 only on the band notified from the band monitor 3. However, the light source drive circuit 61 outputs the excitation light from the selected excitation light source with the 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 band range (numerical range) and the selected excitation light source. The light source drive circuit 61 stores in advance information indicating a correspondence relationship, for example, 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 defined so as not to overlap and to be continuous across a boundary. Further, the smaller the value range, 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 (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 outputs the excitation light from the excitation light source 31 with the excitation light output intensity corresponding to the product of the gain (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 excitation light output intensity according to the product of the gain and the band is the excitation light output intensity defined in the excitation light source 31. Is greater than the upper limit of. Then, the light source drive circuit 61 causes the selected excitation light source 31 to output the excitation light with the excitation light output intensity R1, and as a result, the output monitor 81 immediately instructs the selection of the excitation light source to output the excitation light. As described above, in the above modification, the output monitor 81 may instruct the switching of the excitation light source immediately after the light source drive circuit 61 selects the excitation light source and outputs the excitation light from the excitation light source. ..

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

The optical fiber amplifier of 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 of the first embodiment. The excitation light output intensity monitor 82 and the excitation light sources 31 to 3N have a one-to-one correspondence, and the individual excitation light output intensity monitors 82 are integrated in the corresponding excitation light sources.

Each excitation light output intensity monitor 82 is connected to a 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 a range of excitation light output intensity predetermined for each excitation light source. In the switching instruction circuit 83, for example, the excitation light output intensity range “0 or more and less than R1 (see FIG. 2)” defined in the excitation light source 31 and the excitation light output intensity range “R1 or more R2” defined in the excitation light source 32. Less than (see FIG. 2) ”, the range of excitation light output intensity defined in the excitation light source 33“ R2 or more and less than R3 (see FIG. 2) ”and the like are stored in advance. This point is the same as that of the output monitor 81 in the first embodiment.

Then, the switching instruction circuit 83 receives the notification of the excitation light output intensity from the excitation light output intensity monitor 82 corresponding to the excitation light source that outputs the excitation light. Then, when the excitation light output intensity reaches the boundary value in the range of the excitation light output intensity 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 output excitation light source 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, the switch control circuit 91 is instructed to connect the input end of the switch 71 corresponding to the excitation light source after switching 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 excitation light source after switching 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 use the output monitor 81 in the first embodiment as a portion for monitoring the excitation light output intensity of the excitation light (plurality of excitation light output intensity monitors 82). The configuration is separated from the portion (switching instruction circuit 83) that realizes functions other than the above. 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 functions of the respective elements.

In the second embodiment, the same effect as in the first embodiment can be obtained.

The configuration including the switching instruction circuit 83 and the plurality of excitation light output intensity monitors 82 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 the optical fiber amplifier according to the third embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals as those in FIG. 1, and the description thereof will be omitted.

The optical fiber amplifier of the third embodiment includes one optical fiber 21a instead of the optical fiber 21 of the first embodiment. The optical fiber 21 in the first embodiment is an optical fiber including one core, whereas the optical fiber 21a in the third embodiment is a multi-core optical fiber including a plurality of cores. In the present embodiment, it is assumed that the optical fiber 21a includes K cores.

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

Further, 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, the fiber bundle fan-out 87 is provided on the upstream side of the first signal strength monitor 1, and the optical fiber 21a and the K optical fibers 911 to 91K are connected via the fiber bundle fan-out 87. Has been done. Each of the K optical fibers 911 to 91K includes one core. Further, the first optical isolators 111, 112, ..., 11K are separately connected to the K optical fibers 911 to 91K (see FIG. 5).

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

The fiber bundle fan-out 87 and the fiber bundle fan-in 88 are members having 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 one optical fiber 21a including the plurality of cores. More specifically, it is a member that connects one core contained in each of a plurality of optical fibers and individual cores 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 output separately from the optical fibers 921 to 92K.

Further, the optical combiner 41a in the present embodiment is an optical combiner that synthesizes excitation light with respect to an optical fiber 21a including a plurality of cores by a clad batch method. The optical fiber 21a has a configuration in which a plurality of cores are provided in the clad. The clad batch method is a method in which excitation light is combined with an optical signal passing through each core in the optical fiber 21a by inputting excitation light into the clad.

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 11K provided in each optical fiber 911 to 91K limit the propagation direction of the input optical signal in a certain direction.

The optical signals Lin1 to LinK input to the K optical fibers 911 to 91K pass through different cores existing in one optical fiber 21a by passing through the fiber bundle fanout 87.

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

Further, 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.

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 combiner 41a are the gain control in the first embodiment. The operation is the same as that 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 combiner 41. The switch control circuit 91 selects one excitation light source as in the first embodiment.

However, in the present embodiment, the optical combiner 41a synthesizes the excitation light by the clad batch method with respect to the optical signal passing through each core in the optical fiber 21a.

Further, in the present embodiment, in order to obtain a sufficient excitation light output intensity, it is preferable to use an excitation light source having a multi-mode output as the excitation light sources 31 to 3N. In this case, the N × 1 switch 71 is used together with the excitation light source of the multimode output. Further, it is preferable that the insertion loss of the N × 1 switch 71 is small. Therefore, the N × 1 switch 71 is preferably a mechanically controlled 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 amplified optical signal is at a predetermined constant value by the signal strength notified from the second signal strength monitor 2. If the signal intensity of the entire amplified optical signal 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 one optical fiber 21a by passing through the fiber bundle fan-in 88, and each pass through the separate optical fibers 921 to 92K. go.

According to the present embodiment, high power utilization efficiency can be realized as in the first embodiment. Further, the signal strength can be amplified at the same time for a plurality of optical signals.

Embodiment 4
FIG. 6 is a block diagram showing a configuration example of the optical fiber amplification system according to the fourth embodiment of the present invention. The optical fiber amplification system of the present embodiment includes 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 includes a plurality of optical fiber amplifiers 10. Each optical fiber amplifier 10 may be the optical fiber amplifier of the first embodiment of the present invention (see FIG. 1) or the optical fiber amplifier of the second embodiment of the present invention (see FIG. 4). Good.

The optical fiber amplification system of this 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 to distinguish it from the optical fiber 21 (see FIGS. 1 and 4) provided inside each optical fiber amplifier 10.

Further, the optical fiber amplification system includes a first signal intensity monitor 201, a second signal intensity monitor 202, a gain control circuit 251, a light source drive circuit 261 and an optical combiner 241. Hereinafter, the first signal strength monitor 201, the second signal strength monitor 202, the gain control circuit 251 and the light source drive circuit 261 and the optical combiner 241 are respectively provided with similar elements and sections of the optical fiber amplifier 10. Separately, the first external signal strength monitor 201, the second external signal strength monitor 202, the external gain control circuit 251 and the external light source drive circuit 261 and the external optical combiner 241 are described. The optical fiber amplification system includes one excitation light source 231 outside each optical fiber amplifier 10.

Further, the optical fiber amplification system includes a fiber bundle fan-out 287, a fiber bundle fan-in 288, and a plurality of optical fibers 931 to 93K connected to the upstream side of the fiber bundle fan-out 287. Hereinafter, it is assumed that the number of optical fibers connected to the upstream side of the fiber bundle fanout 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, it is assumed that the external optical fiber 221 includes K cores.

Rare earth ions (here, erbium ions) are added to the external optical fiber 221. Here, it is assumed that the erbium ion is 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 contains one core.

In the external optical fiber 221, the first external signal strength monitor 201 is connected to the upstream side of the start position A'of the erbium ion addition range. A fiber bundle fanout 287 is provided on the upstream side. The fiber bundle fan-out 287 connects the K optical fibers 913 to 93K and the external optical fiber 221. Further, optical isolators 211, 212, ..., 21K are individually connected to the K optical fibers 913 to 93K (see FIG. 6). Hereinafter, the optical isolators 221 to 21K will be referred to as external optical isolators 211 to 21K to distinguish them from the first optical isolator 11 and the second optical isolator 12 provided in each optical fiber amplifier 10.

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

As described above, the fiber bundle fan-out and the fiber bundle fan-in are members having a common configuration. Specifically, one core contained in each of a plurality of optical fibers and individual cores contained in one optical fiber (here, an external optical fiber 221) are arranged one-to-one. It is a member to be connected to.

Further, the first external signal strength monitor 201 and the second external signal strength monitor 202 are each connected to the external gain control circuit 251. 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 combiner 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 signal strength to the external gain control circuit 251. The external gain control circuit 251 calculates the gain between the signal strength of the entire optical signals Lin1 to LinK and the signal strength to be constant so that the signal strength of each of the amplified optical signals becomes a constant value. 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 realized by, for example, dedicated processors. Further, for example, the external gain control circuit 251 and the external light source drive circuit 261 may be realized by one processor having the functions of the respective elements.

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 913 to 93K. The external optical isolators 211 to 21K provided in each optical fiber 913 to 93K limit the input optical signal propagation direction to a certain direction.

The optical signals Lin1 to LinK separately input to the K optical fibers 913 to 93K pass through the separate cores existing in one external optical fiber 221 by passing through the fiber bundle fanout 287. ..

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

The external gain control circuit 251 calculates the gain between 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 amplified optical signal becomes constant. To do. In other words, the external gain control circuit 251 calculates the gain when amplifying the signal strength of the entire 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 has the signal strength notified from the first signal strength monitor 201 and its signal strength. And the gain may be calculated.

The external light source drive circuit 261 drives only the excitation light source 231. The external light source drive circuit 261 outputs the excitation light from the excitation light source 231 with the 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 excitation light output intensity as the gain value increases, and decreases the excitation light output intensity as the gain value decreases.

The excitation light output by the excitation light source 231 is input to the external optical combiner 241. The external optical combiner 241 synthesizes excitation light for an optical signal passing through each core in the external optical fiber 221 by a clad batch method. That is, the external optical combiner 241 inputs the excitation light into the cladding of the external optical fiber 221 to synthesize the excitation light into the respective optical signals Lin1 to LinK.

The signal intensity of each optical signal is amplified by passing each optical signal in which the excitation light is synthesized passes through the addition range of erbium ions in the external optical fiber 221.

Further, the second external signal strength monitor 202 monitors the signal strength of each 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 optical signal after amplification is a predetermined constant by the signal strength notified from the second signal strength monitor 2. If the signal strength does not reach a predetermined constant value, the external gain control circuit 251 adjusts the calculated gain. This operation is the same as 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 each of K separate optical fiber amplifiers 10. To.

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

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

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

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, the optical signals Lin1 to LinK are amplified by one external optical fiber 221 and then amplified again 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 that of the first embodiment and the second embodiment can be obtained.

In this embodiment, there is only one excitation light source 231 that outputs excitation light to the external optical fiber 221. Then, the amplification of each optical signal Lin1 to LinK in the external optical fiber 221 may vary. However, after that, each optical signal is amplified again by K optical fiber amplifiers 10. Therefore, the variation in amplification generated in each optical signal in the external optical fiber 221 can be adjusted by each optical fiber amplifier 10.

Embodiment 5.
FIG. 7 is a block diagram showing a configuration example of the optical fiber amplifier according to the 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 each optical signal is output as optical signals Lout1 to LoutK after amplification. Each optical signal passes through a separate optical fiber.

Hereinafter, in the fifth embodiment, as an example, 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 271-27K as an example. explain.

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

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

Further, in the fifth embodiment, the optical fiber amplifier is a first optical isolator, a first signal intensity monitor, an optical combiner, a second signal intensity monitor, a second optical isolator and a gain for each optical fiber. It has a control circuit.

Therefore, the optical fiber amplifier includes K first optical isolators 31 to 31K, K first signal intensity monitors 810 to 81K, K optical combiners 411 to 41K, and K second. The signal strength monitors 821 to 82K, K second optical isolators 3213 to 22K, and K gain control circuits 511 to 51K are provided.

The first optical isolators 31 to 31K are all the same as the first optical isolator 11 in the first embodiment. Further, the second optical isolators 321 to 322K are all the same as the second optical isolator 12 in the first embodiment. All of the first signal strength monitors 811 to 81K are the same as the first signal strength monitor 1 in the first embodiment. Further, the second signal strength monitors 821 to 82K are all the same as the second signal strength monitor 2 in the first embodiment. All of the optical combiners 411 to 41K are the same as the optical combiner 41 in the first embodiment. Further, the gain control circuits 511 to 51K are all the same as the gain control circuit 51 in the first embodiment. The above-mentioned elements similar to those of the first embodiment will not be described.

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

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

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

Each excitation light source 31 to 3M is connected to the light source drive circuit 561. Similar to the first embodiment, each of the excitation light sources 31 to 3M is an excitation light source having different excitation light output intensity vs. power consumption characteristics. The excitation light output intensity vs. power consumption characteristics of each excitation light source 31 to 3M may be changed, for example, by changing the maximum heat absorption amount of the Pertier cooler provided in each excitation light source.

The M × K switch 571 is a switch having M input ends of excitation light and K output ends of excitation light. The input terminals I1 to IM of the M × K switch 571 have a one-to-one correspondence with the excitation light sources 31 to 3M, and each input terminal I1 to IM is connected to the corresponding excitation light source. Further, the output ends O1 to OK of the M × K switch 571 correspond one-to-one with the optical fibers 271 to 27K, and each output end O1 to OK corresponds to the optical combiner 411 to 41K provided in the corresponding optical fiber. 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 (band used for signal transmission) for each optical fiber 271-27K, and determines the band of the optical signal obtained for each optical fiber 271-227K. Notify the light source drive circuit 561 respectively.

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

As a result, the light source drive circuit 561 obtains a pair 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 excitation light source to output excitation light for each optical fiber based on the product of gain and standby. Therefore, the light source drive circuit 561 selects K excitation light sources.

The method in which the light source drive circuit 561 selects one excitation light source for each 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 of the product of the gain and the band (numerical range) and the selected excitation light source. The light source drive circuit 561 stores in advance information indicating a correspondence relationship, for example, the range "0 or more and less than T1" corresponds to the excitation light source 31, and the range "T1 or more and less than T2" corresponds to the excitation light source 32. ing.

For example, it is assumed that the product of the gain obtained from the optical fiber 271 and the band 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. Further, for example, it is assumed that the product of the gain obtained from the optical fiber 272 and the band 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 that outputs the excitation light to the optical fiber 272.

The light source drive circuit 561 drives each of the selected excitation light sources and causes the excitation light source to output the excitation light. At this time, the light source drive circuit 561 outputs the excitation light from the excitation light source with the excitation light output intensity corresponding to the product of the gain obtained from the optical fiber corresponding to the excitation light source and the band. For example, it is assumed that the light source drive circuit 561 selects the excitation light source 31 as the excitation light source that outputs the excitation light to the optical fiber 271. In this case, the light source drive circuit 561 outputs the excitation light from the excitation light source 31 with the excitation light output intensity corresponding to the product of the gain obtained from the optical fiber 271 and the band. In the light source drive circuit 561, the larger the value of the product of the gain and the band, the higher the excitation light output intensity, and the smaller the value of the product of the gain and the band, the lower the excitation light output intensity. The light source drive circuit 561 drives the other selected excitation light sources in the same manner.

Further, when the excitation light source is selected for each optical fiber, the light source drive circuit 561 has an input terminal of the M × K switch 71 corresponding to the excitation light source and an M × K switch corresponding to the optical combiner provided in the optical fiber. The switch control circuit 591 is instructed to connect to the output terminal of 71. For example, as described above, it is assumed that the excitation light source 31 is selected as the excitation light source that outputs 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 combiner 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 groups. 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 once selects an excitation light source for each optical fiber, and then switches the excitation light source to output the excitation light according to the instruction of the output monitor 581.

The output monitor 581 monitors the excitation light output intensity of the excitation light output from the light output ends 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 a range of excitation light output intensity predetermined for each excitation light source. The output monitor 581 is, for example, a range of excitation light output intensity defined for the excitation light source 31 “0 or more and less than R1 (see FIG. 2)” and a range of excitation light output intensity defined for the excitation light source 32 “R1 or more and less than R2”. (See FIG. 2) ”, the range of excitation light output intensity defined in the excitation light source 33“ R2 or more and less than R3 (see FIG. 2) ”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 excitation light to the optical fiber when the product of the gain and the band changes due to a change in either or both of the gain and the band obtained from the optical fiber for each optical fiber. The excitation light output intensity of the excitation light source is changed. The output monitor 581 sets the excitation light output intensity of the excitation light output from any of the excitation light sources that output the excitation light to the boundary value in 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 range adjacent to 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 connects the switch control circuit 591 to the output end to which the input end corresponding to the excitation light source before switching is connected and the input end corresponding to the excitation light source after switching. Instruct. 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 circuit 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 circuit 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 functions of the respective elements.

The optical fiber amplifier of the fifth embodiment performs the same processing on each input optical signal 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. The matters already described in the first embodiment will be omitted as appropriate.

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.

Further, 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 gains 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 when 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 an excitation light source that outputs excitation light to the optical fiber 271 according to the product. Here, the light source drive circuit 561 will be described with the excitation light source 31 selected.

Then, the light source drive circuit 561 switches 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 combiner 411 provided in the optical fiber 271. Instruct the control circuit 591. The switch control circuit 591 connects the input terminal I1 and the output terminal O1 according to the instruction.

Further, the light source drive circuit 561 outputs excitation light from the excitation light source 31 with an excitation light output intensity corresponding to the product of the above gain and band. The excitation light is input to the input terminal I1 of the M × K switch 571 and output from the output terminal O1. The optical combiner 411 synthesizes the excitation light with the optical signal Lin1. As a result, the signal strength of the optical signal Lin1 is amplified to a constant signal strength and output as the optical 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 is set to a predetermined constant value by the signal strength notified from the second signal strength monitor 821. If the signal intensity of the optical signal Lout is not a predetermined constant value, the gain control circuit 511 subsequently adjusts the calculated gain.

Further, the second optical isolator 321 limits the propagation direction of the optical signal Lout1 to a certain direction.

The optical fiber amplifier performs the same processing for other input optical signals Lin2 to LinK. As a result, each of the input optical signals Lin1 to LinK is amplified.

Further, in the output monitor 581, the excitation light output intensity of the excitation light output from any of the excitation light sources that output the excitation light is the boundary of the range of the excitation light output intensity defined for the excitation light source. When the value is reached, 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 range adjacent to 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, it is assumed that the input end I1 and the output end O1 are connected in the M × K switch 571. 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 excitation light output intensity of the excitation light output from the excitation light source 31 becoming R1. Instruct the drive circuit 561. The light source drive circuit 561 switches the excitation light source that outputs the excitation light from the excitation light source 31 to the excitation light source 32.

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

In the above description, switching of the excitation light source that outputs the 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 when switching the excitation light source that outputs the excitation light to another optical fiber are the same as described above.

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

Further, according to the present embodiment, the signal intensities of the plurality of optical signals Lin1 to LinK can be individually amplified.

Further, the optical fiber amplifier of this embodiment includes an M × K switch 571. Therefore, it is possible to prevent an increase in the number of excitation light sources. For example, when the N × 1 switch in the first embodiment is used, N excitation light sources are required for each optical fiber. Therefore, 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, if K <M or K = M is satisfied, M excitation light sources may be provided for K optical fibers, and the excitation light sources may be provided. The increase in number can be prevented.

Further, in each of the above embodiments, the case where the optical combiner is arranged on the upstream side within the addition range of erbium ions in the optical fiber and the optical signal and the excitation light propagate in the same direction in the optical fiber is taken as an example. I explained. A mode for amplifying the signal intensity of an optical signal in such a mode is called forward excitation.

In each embodiment of the present invention, the optical combiner is arranged on the downstream side within the addition range of erbium ions in the optical fiber, and the propagation direction of the optical signal and the propagation direction of the excitation light are opposite in the optical fiber. The optical combiner may input the excitation light into the optical fiber so as to be. A mode for amplifying the signal intensity of an optical signal in such a mode is called backward excitation. Backward excitation may be employed in each embodiment of the present invention.

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

Further, the optical isolators shown in the above embodiments are provided for the purpose of preventing oscillation of the optical fiber amplifier due to multiple reflection of optical signals. In each of the above embodiments, if a long optical fiber is used as the optical fiber to maintain a high reflection attenuation amount, an optical isolator may not be provided.

Next, the 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 includes an optical fiber 1021, a plurality of light sources 1031 to 103N, a light source driving means 1061, a synthesis means 1041, and a switch 1071.

An optical fiber 1021 (for example, an optical fiber 21, an optical fiber 21a, an optical fiber 271-27K, etc.) passes an optical signal, and when excitation light is synthesized with the optical signal, the signal intensity of the optical signal is amplified. 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 vs. power consumption characteristics. ..

The light source driving means 1061 (for example, the light source driving circuit 61, the light source driving circuit 561, etc.) outputs excitation light from the light source.

The synthesizing means 1041 (for example, an optical combiner 41, an optical combiner 41a, an optical combiner 411 to 41K, etc.) synthesizes the excitation light output from the light source into an optical signal.

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

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

Each embodiment of the present invention described above may also be described as in the appendix below, but is not limited to:

(Appendix 1)
An optical fiber that amplifies the signal intensity of the optical signal when the excitation light is synthesized with the optical signal after passing the optical signal.
A plurality of light sources that output the excitation light, and a plurality of light sources having different excitation light output intensity vs. power consumption characteristics.
A light source driving means that outputs excitation light from the light source,
A synthesis means for synthesizing the excitation light output from the light source into the optical signal,
An optical fiber amplifier comprising an input end of excitation light corresponding to a light source for each individual light source, and a switch having an output end for outputting the excitation light to the synthesis means.

(Appendix 2)
A switch control means for controlling the input end connected to the output end of the switch is provided.
The excitation light output intensity of the excitation light output from the light source is monitored, and when the excitation light output intensity reaches a boundary value within the range of the excitation light output intensity defined for the light source, the light source driving means. 2. The switch control means is provided with a switching instruction means for instructing the switch control means to connect the input end corresponding to the light source after the switching to the output end, as well as instructing the switching of the light source for outputting the excitation light. Optical fiber amplifier.

(Appendix 3)
The optical fiber amplifier according to Appendix 1 or Appendix 2, wherein each of the plurality of light sources is provided with a Pertier cooler, and the maximum heat absorption of each Pertier cooler corresponding to each light source is different.

(Appendix 4)
A gain calculation means for calculating the gain between the signal strength of an optical signal input to an optical fiber and a predetermined signal strength, and
It is provided with a band monitoring means for monitoring the band used for signal transmission in the optical signal input to the optical fiber.
The light source driving means selects a light source to output the excitation light based on at least the band, and outputs the excitation light from the light source with the excitation light output intensity corresponding to the product of the gain and the band. The optical fiber amplifier according to any one of Appendix 3.

(Appendix 5)
A gain calculation means for calculating the gain between the signal strength of an optical signal input to an optical fiber and a predetermined signal strength, and
It is provided with a band monitoring means for monitoring the band used for signal transmission in the optical signal input to the optical fiber.
The light source driving means selects a light source that outputs excitation light based on the product of the gain and the band, and excite light from the light source with an excitation light output intensity corresponding to the product of the gain and the band. The optical fiber amplifier according to any one of Supplementary note 1 to Supplementary note 4.

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

(Appendix 7)
The optical fiber amplifier according to Appendix 6, wherein the synthesizing means synthesizes excitation light with an optical signal by a core individual method.

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

(Appendix 9)
The optical fiber amplifier according to Appendix 8, wherein the synthesizing means synthesizes excitation light with an optical signal by a clad batch method.

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

(Appendix 11)
The optical fiber amplifier according to any one of Appendix 1 to Appendix 10, wherein the optical fiber is an optical fiber to which rare earth ions are added.

(Appendix 12)
A plurality of optical fiber amplifiers according to Appendix 6 or Appendix 7 are provided.
It includes a plurality of cores corresponding to the cores in the optical fiber in each optical fiber amplifier, and includes one external optical fiber provided outside the plurality of optical fiber amplifiers.
An optical fiber amplification system including one external light source that outputs excitation light to the external optical fiber.

Although the invention of the present application has been described above with reference to the embodiments, the invention of the present application is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made within the scope of the present invention in terms of the structure and details of the present invention.

This application claims priority on the basis of Japanese Patent Application 2017-126622 filed on June 28, 2017, and incorporates all of its disclosures herein.

Possibility of industrial use

The present invention is suitably applied to an optical fiber amplifier and an optical fiber amplification system that amplify the signal intensity of an optical signal.

1 1st signal intensity monitor 2 2nd signal intensity monitor 3 Band monitor 11 1st optical isolator 12 2nd optical isolator 21 Optical fiber 31 to 3N excitation light source 41 Optical combiner 51 Gain control circuit 61 Light source drive circuit 71 Switch 81 Output monitor 91 Switch control circuit

Claims (9)

An optical fiber that amplifies the signal intensity of the optical signal when the excitation light is synthesized with the optical signal after passing the optical signal.
A plurality of light sources that output the excitation light, and a plurality of light sources having different excitation light output intensity vs. power consumption characteristics.
A light source driving means that outputs excitation light from the light source,
A synthesis means for synthesizing the excitation light output from the light source into the optical signal,
A switch having an input end of excitation light corresponding to the light source for each individual light source and an output end for outputting the excitation light to the synthesis means .
A switch control means for controlling an input end connected to an output end in the switch,
The excitation light output intensity of the excitation light output from the light source is monitored, and when the excitation light output intensity reaches a boundary value within the range of the excitation light output intensity defined for the light source, the light source drive is performed. The means is provided with a switching instruction means for instructing the switching of the light source for outputting the excitation light and instructing the switch control means to connect the input end corresponding to the light source after the switching to the output end. Optical fiber amplifier. Each of the multiple light sources has a Pertier cooler, and the maximum heat absorption of each Pertier cooler corresponding to each light source is different.
The optical fiber amplifier according to claim 1. A gain calculation means for calculating the gain between the signal strength of an optical signal input to an optical fiber and a predetermined signal strength, and
It is provided with a band monitoring means for monitoring the band used for signal transmission in the optical signal input to the optical fiber.
The light source driving means selects a light source to output the excitation light based on at least the band, and outputs the excitation light from the light source with the excitation light output intensity corresponding to the product of the gain and the band.
The optical fiber amplifier according to claim 1 or 2. A gain calculation means for calculating the gain between the signal strength of an optical signal input to an optical fiber and a predetermined signal strength, and
It is provided with a band monitoring means for monitoring the band used for signal transmission in the optical signal input to the optical fiber.
The light source driving means selects a light source that outputs excitation light based on the product of the gain and the band, and excite light from the light source with an excitation 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 3. It said optical fiber is a single optical fiber having a single core,
The optical fiber amplifier according to claim 3 or 4 , wherein the light source driving means selects one light source for outputting excitation light. It said optical fiber is a single optical fiber having a plurality of cores,
The optical fiber amplifier according to claim 3 or 4 , wherein the light source driving means selects one light source for outputting excitation light. It said optical fiber is a plurality of optical fibers having a single core,
Each optical fiber is equipped with a synthesis means
The switch has an output end corresponding to the synthesis means for each individual synthesis means.
The optical fiber amplifier according to claim 3 or 4 , wherein the light source driving means selects one light source for outputting excitation light for each optical fiber. The optical fiber amplifier according to any one of claims 1 to 7 , wherein the optical fiber is an optical fiber to which rare earth ions are added. A plurality of optical fiber amplifiers according to claim 5 are provided.
It includes a plurality of cores corresponding to the cores in the optical fiber in each optical fiber amplifier, and includes one external optical fiber provided outside the plurality of optical fiber amplifiers.
An optical fiber amplification system including one external light source that outputs excitation light to the external optical fiber.

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