Light amplifier and light amplification method

Abstract

To provide a light amplifier and a light amplification method for solving the problem of occurrence of difficulty in connecting a multi-core light transmission line with a multi-core light amplifier in a multi-core optical fiber transmission system.SOLUTION: A light amplifier includes: multi-core optical amplification means comprising a plurality of amplification cores; and connection means for connecting the multi-core optical amplification means with a multi-core light transmission line comprising a plurality of light transmission line cores. The total sum of the number of the plurality of amplification cores is equal to or larger than the number of transmission cores in which signal light propagates of the plurality of transmission cores.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical amplifier and an optical amplification method, and more particularly to an optical amplifier and an optical amplification method used in a multi-core optical fiber transmission system. [Background technology]

[0002] The rapid expansion of mobile traffic and video services has led to a demand for increased communication capacity in core networks. This demand for increased capacity is likely to continue in the future. Up until now, this expansion has been achieved by using time-division multiplexing and wavelength-division multiplexing technologies. These time-division multiplexing and wavelength-division multiplexing technologies have been applied to optical communication systems using single-core optical fibers.

[0003] To further expand communication capacity, spatial multiplexing technology, which is a multiplexing technology of a different dimension from previous multiplexing technologies, is being developed. Spatial multiplexing technologies include multi-core technology, which increases the number of cores per optical fiber, and multi-mode technology, which increases the number of propagation modes. The number of cores and modes currently used in optical fiber communications is one. Therefore, it is possible to dramatically expand communication capacity by increasing the number of cores and modes.

[0004] There are two optical amplification methods suitable for multi-core optical fibers used in multi-core technology: core pumping and cladding pumping. In the core pumping method, the intensity of the optical signal transmitted through each core is amplified individually using an individual pumping light source for each core. On the other hand, in the cladding pumping method, the intensity of the optical signal transmitted through each core is amplified collectively using a common pumping light source.

[0005] In order to efficiently amplify the optical intensity of optical signals transmitted through a multi-core optical fiber, a cladding pumping scheme is desirable, in which the intensity of optical signals transmitted through each core is amplified collectively using a common pumping light source. In addition, in the cladding pumping scheme, the configuration of a current single-core pumping optical amplifier can, in principle, be used as is for a cladding pumping optical amplifier.

[0006] An example of such an optical amplifier using a cladding pumping method is described in Patent Document 1.

[0007] The related optical amplifier described in Patent Document 1 includes a multi-core optical fiber 91, a pumping light source 92, an optical isolator 94, an optical multiplexer 93, and multi-core optical fibers 97#1 and 97#2. Here, the multi-core optical fiber 91 includes a plurality of cores doped with rare-earth ions arranged in a first cladding. Furthermore, the multi-core optical fiber 91 includes a second cladding arranged around the first cladding and reflecting pumping light having a wavelength that excites the rare-earth ions. The plurality of cores are configured to have an inter-core distance that allows propagating light to be coupled.

[0008] Related techniques include those described in Patent Documents 2 and 3. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-21070 [Patent Document 2] Japanese Patent Application Publication No. 2019-139029 [Patent Document 3] Special Publication No. 2020-513162 Summary of the Invention [Problem to be solved by the invention]

[0010] In a multi-core optical fiber transmission system using a multi-core optical fiber, a multi-core optical amplifier such as the related optical amplifier described above is inserted between the multi-core optical transmission lines. Therefore, each core of the multi-core optical transmission line and each core of the multi-core optical amplifier need to be optically connected. However, a multi-core optical fiber has limitations on the number of cores and their arrangement in order to densely pack the cores. As a result, the number of cores in the multi-core optical transmission line and the number of cores in the multi-core optical amplifier may not match, making it difficult to connect the multi-core optical transmission line and the multi-core optical amplifier.

[0011] As described above, in a multi-core optical fiber transmission system, there is a problem in that it may be difficult to connect a multi-core optical transmission line and a multi-core optical amplifier.

[0012] An object of the present invention is to provide an optical amplification device and an optical amplification method that solve the above-mentioned problem that in a multi-core optical fiber transmission system, it may be difficult to connect a multi-core optical transmission line and a multi-core optical amplifier. [Means for solving the problem]

[0013] The optical amplification device of the present invention comprises a multi-core optical amplification means having a plurality of amplification cores, and a connection means for connecting the multi-core optical amplification means to a multi-core optical transmission line having a plurality of transmission line cores, wherein the total number of the plurality of amplification cores is equal to or greater than the number of transmission cores among the plurality of transmission line cores through which signal light propagates.

[0014] The optical amplification method of the present invention connects a multi-core optical amplifier having a plurality of amplification cores to a multi-core optical transmission line having a plurality of transmission line cores so that the total number of the plurality of amplification cores is equal to or greater than the number of transmission line cores through which signal light propagates, and amplifies the signal light using the plurality of amplification cores. [Effects of the Invention]

[0015] According to the optical amplification device and optical amplification method of the present invention, even if the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier, it is possible to connect the multi-core optical transmission line and the multi-core optical amplifier. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a configuration of an optical amplifying device according to a first embodiment of the present invention. [Figure 2] 3 is a flowchart illustrating an optical amplification method according to the first embodiment of the present invention. [Figure 3] FIG. 10 is a block diagram showing the configuration of an optical amplifying device according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a block diagram showing another configuration of an optical amplifying device according to the second embodiment of the present invention. [Figure 5] FIG. 10 is a diagram illustrating an example of information related to the configuration of a multi-core optical amplifying unit included in an optical amplifying device according to a second embodiment of the present invention. [Figure 6] 10 is a flowchart illustrating an optical amplification method according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a block diagram showing the configuration of an optical amplifying device according to a third embodiment of the present invention. [Figure 8] 10 is a flowchart illustrating an optical amplification method according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] [First embodiment] 1 is a block diagram showing the configuration of an optical amplifier 100 according to a first embodiment of the present invention. The optical amplifier 100 includes a multi-core optical amplifier section (multi-core optical amplifying means) 110 and a connection section (connecting means) 120.

[0019] The multi-core optical amplifier 110 includes a plurality of amplification cores. The connection unit 120 connects the multi-core optical amplifier 110 to the multi-core optical transmission line 10, which includes a plurality of transmission line cores. Here, the total number of the plurality of amplification cores is equal to or greater than the number of transmission line cores through which signal light propagates.

[0020] As described above, the optical amplifying device 100 of this embodiment is configured to include a multi-core optical amplifying section 110 in which the total number of amplification cores is equal to or greater than the number of transmission cores. Therefore, the optical amplifying device 100 of this embodiment can connect a multi-core optical transmission line to a multi-core optical amplifier even if the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier.

[0021] Here, each of the multiple amplification cores contains rare earth ions, and the multi-core optical amplification unit 110 can have a double-clad structure. As the multi-core optical amplification unit 110, a multi-core erbium-doped fiber (MC-EDF) that uses erbium ions as the rare earth ions can typically be used.

[0022] The multi-core optical amplifier 110 can be configured to include multiple multi-core optical amplifiers with different numbers of amplification cores. Mixing multi-core optical amplifiers with different numbers of cores increases the degree of freedom in combinations, which makes it possible to increase the options for connection configurations between multi-core optical transmission lines and multi-core optical amplifiers.

[0023] The connection unit 120 can be configured to connect the multi-core optical amplifier unit 110 and the multi-core optical transmission line 10 according to the operation mode of the optical amplifier device 100. As described above, by mixing multi-core optical amplifier units with different numbers of cores, it is possible to increase the degree of freedom in selecting a connection topology according to the operation mode.

[0024] When this operation mode is a mode that minimizes power consumption, the connection unit 120 connects the multi-core optical amplifier units 110 to the multi-core optical transmission line 10 in a connection configuration that minimizes the sum of the pump light intensities of each multi-core optical amplifier unit 110. Here, the pump light intensity is determined by the configuration of the multi-core optical amplifier unit 110, including the number of amplification cores. Specifically, when a multi-core erbium-doped fiber (MC-EDF) is used as the multi-core optical amplifier unit 110, the pump light intensity depends on the cladding diameter and the number of cores, and is determined by the ratio of the total cross-sectional area of ​​the cores to the cross-sectional area of ​​the fiber.

[0025] Furthermore, when the operating mode is a mode that maximizes the optical amplification degree, the connection unit 120 connects the multi-core optical amplifier units 110 to the multi-core optical transmission line 10 in a connection configuration that maximizes the sum of the pumping densities for each multi-core optical amplifier unit 110. Here, the pumping density is determined by the configuration of the multi-core optical amplifier unit 110, including the number of multiple amplification cores. Specifically, when a multi-core erbium-doped fiber (MC-EDF) is used as the multi-core optical amplifier unit 110, the pumping density depends on the cladding diameter and the number of cores, and is determined by the ratio of the total cross-sectional area of ​​the cores to the cross-sectional area of ​​the fiber.

[0026] In this way, by setting the operation mode based on the predetermined required specifications, it is possible to simplify the configuration and reduce the cost of the multi-core optical amplifier unit 110. Note that the operation mode is not limited to the above-mentioned mode that minimizes power consumption and mode that maximizes optical amplification, but any operation mode can be set according to the required specifications.

[0027] Next, the optical amplification method according to this embodiment will be described with reference to the flowchart shown in FIG.

[0028] In the optical amplification method according to this embodiment, first, a multi-core optical amplifier including a plurality of amplification cores is connected to a multi-core optical transmission line including a plurality of transmission line cores (step S11). k The sum of (Σ(m k ×N k)) are connected so that the number of transmission cores through which the signal light propagates among the multiple transmission line cores is equal to or greater than n. k " denotes the number of multi-core optical amplifiers, and "k" denotes a variable used to calculate the sum. Then, the signal light is amplified by these multiple amplification cores (step S12).

[0029] As described above, the optical amplification method of this embodiment is configured to connect a multi-core optical amplifier to a multi-core optical transmission line so that the total number of amplification cores is equal to or greater than the number of transmission cores. Therefore, the optical amplification method of this embodiment makes it possible to connect a multi-core optical transmission line to a multi-core optical amplifier even when the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier.

[0030] Connecting the multi-core optical amplifier and the multi-core optical transmission line (step S11) may include connecting the multi-core optical amplifier and the multi-core optical transmission line according to an overall operation mode of the multi-core optical amplifier.

[0031] When this operation mode is a mode for minimizing power consumption, connecting the multi-core optical amplifier to the multi-core optical transmission line includes connecting the multi-core optical amplifier to the multi-core optical transmission line in a connection configuration that minimizes the sum of the pump light intensities of each multi-core optical amplifier, where the pump light intensity is determined by the configuration of the multi-core optical amplifier, including the number of amplification cores.

[0032] Furthermore, when the operation mode is a mode that maximizes the optical amplification degree, connecting the multi-core optical amplifier to the multi-core optical transmission line includes connecting the multi-core optical amplifier to the multi-core optical transmission line in a connection configuration that maximizes the sum of the pumping densities of each multi-core optical amplifier, where the pumping density is determined by the configuration of the multi-core optical amplifier, including the number of amplifying cores.

[0033] As described above, according to the optical amplification device 100 and optical amplification method of this embodiment, even if the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier, it is possible to connect the multi-core optical transmission line to the multi-core optical amplifier.

[0034] Second Embodiment Next, a second embodiment of the present invention will be described. Fig. 3 shows the configuration of an optical amplifier 1000 according to this embodiment. The optical amplifier 1000 has a multi-core optical amplifier section (multi-core optical amplifying means) 1100 and a connection section (connecting means) 1200.

[0035] The multi-core optical amplifier 1100 includes a plurality of amplification cores. Each of the plurality of amplification cores contains rare-earth ions, and the multi-core optical amplifier 1100 may have a double-clad structure. A multi-core erbium-doped fiber (MC-EDF) using erbium ions as the rare-earth ions can typically be used as the multi-core optical amplifier 1100. The multi-core optical amplifier 1100 may include a plurality of multi-core optical amplifiers each having a different number of amplification cores. FIG. 3 shows, as an example, a configuration including four multi-core optical amplifiers 1101 to 1104. Here, the number of amplification cores is, for example, two for the multi-core optical amplifier 1101, four for the multi-core optical amplifier 1102, seven for the multi-core optical amplifier 1103, and 19 for the multi-core optical amplifier 1104.

[0036] The connection unit 1200 connects the multi-core optical amplifier unit 1100 and the multi-core optical transmission line 10 having a plurality of transmission line cores. As an example, Fig. 3 shows a configuration including a first connection unit 1210 that connects the multi-core optical transmission line 11 on the input side to the multi-core optical amplifier unit 1100, and a second connection unit 1220 that connects the multi-core optical transmission line 12 on the output side to the multi-core optical amplifier unit 1100.

[0037] Here, the total number of the multiple amplification cores is equal to or greater than the number of transmission cores through which signal light propagates among the multiple transmission line cores. Therefore, according to the optical amplifying device 1000 of this embodiment, even if the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier, it is possible to connect the multi-core optical transmission line to the multi-core optical amplifier.

[0038] Specifically, for example, in the above example, the total number of amplification cores is 32 (=2+4+7+19), and the multi-core optical transmission line 10 has 40 transmission line cores, and the signal light can be configured to propagate through 14 transmission cores.

[0039] The connection unit 1200 can be configured to connect the multi-core optical amplifier unit 1100 and the multi-core optical transmission line 10 according to the operation mode of the optical amplifier device 1000. In the optical amplifier device 1000 of this embodiment, the connection unit 1200 is configured to switch the connections between the multiple amplification cores and the multiple transmission line cores according to the operation mode. That is, the connection unit 1200 is configured to be able to switch and control so that any transmission line core in the multi-core optical transmission line 10 is connected to any one of the multi-core optical amplifier units 1101 to 1104.

[0040] Specifically, as shown in Fig. 3, the first connecting unit 1210 and the second connecting unit 1220 are configured to include first fan-in fan-out units (first fan-in fan-out means) 1211, 1221, optical switching units (optical switching means) 1212, 1222, and second fan-in fan-out units (second fan-in fan-out means) 1213, 1223, respectively. The first fan-in fan-out units 1211, 1221 connect multiple transmission line cores to the first single-core optical transmission line, respectively. The optical switching units 1212, 1222 switch the connection between the first single-core optical transmission line and the second single-core optical transmission line. The second fan-in fan-out units 1213, 1223 connect the second single-core optical transmission line to multiple amplification cores, respectively.

[0041] Optical switches can typically be used as the optical switching units 1212 and 1222. For example, the first fan-in fan-out unit 1211 can be a fan-out (1:n FO) that couples "n" transmission cores of one input-side multi-core optical transmission line 11 to "n" first single-core optical transmission lines, respectively. Furthermore, the second fan-in fan-out unit 1213 can be a fan-in (2:1 FI) that couples two second single-core optical transmission lines to two amplification cores of one multi-core optical amplifier unit 1101, for example.

[0042] As shown in Fig. 4, the optical amplifier 1000 can be configured to have a pumping light generating section (pumping light generating means) 1300, a variable branching section (variable branching means) 1400, and a control section 1500 equipped with a pumping light control section (pumping light control means). Fig. 4 also shows a combiner 1410 that couples pumping light to the multi-core optical fiber.

[0043] The pumping light generating unit 1300, the variable branching unit 1400, and the pumping light control unit constitute the pumping light introducing unit, which introduces the pumping light for exciting the multiple amplification cores into the multi-core optical amplifying unit 1100 by a cladding pumping method. By using the cladding pumping method, the number of pumping light generating units 1300 can be reduced to one regardless of the number of amplification cores, thereby enabling the optical amplifying device 1000 to be made smaller.

[0044] The pumping light generating unit 1300 generates pumping light. Here, the pumping light generating unit 1300 can be configured to include a plurality of light sources 1310 that generate laser light, and a multiplexing unit (multiplexing means) 1320 that multiplexes the laser light generated by the plurality of light sources and transmits the pumping light. In this way, by including a plurality of light sources 1310, it is possible to generate pumping light even if one of the light sources fails. A semiconductor laser can typically be used as the light source 1310. FIG. 4 also shows a driver 1330 for driving the light source 1310.

[0045] The variable branching unit 1400 branches the pump light and supplies the branched pump light to the multi-core optical amplifier unit 1100. The variable branching unit 1400 may be, for example, a variable coupler.

[0046] The pump light control unit included in the control unit 1500 determines the branching ratio of the variable branching unit 1400 depending on the operation mode, and sets the determined branching ratio in the variable branching unit 1400. This makes it possible to supply pump light only to the multi-core optical amplification units 1101 to 1104 that need to be in an operating state depending on the operation mode.

[0047] The control unit 1500 may be configured to include a connection topology determination unit (connection topology determination means). The connection topology determination unit determines the connection topology between the multi-core optical transmission line 10 and the multi-core optical amplifier unit 1100 according to the operation mode, using information on the number of transmission cores and the configuration of the multi-core optical amplifier unit 1100. The control unit 1500 then controls the optical switching units 1212 and 1222 to achieve the determined connection topology.

[0048] An example of information relating to the configuration of the above-mentioned multi-core optical amplifier 1100 is shown in Fig. 5. In Fig. 5, the information (parameters) relating to the configuration of the multi-core optical amplifier 1100 include the pumping density ratio η for each number of cores in the multi-core optical amplifier 1100, the optical power [W / core] required to generate an excited state, and the required pumping optical power P [W].

[0049] The pumping density ratio η is set to 1 W / μm for the multi-core optical amplifier 1100 with two cores. 2 The pumping density is proportional to the optical amplification efficiency of the multi-core optical amplifier section 1100, and therefore affects the achievable optical amplification degree and maximum output optical intensity.

[0050] The optical power required to generate the pumped state is shown as a value per core when the optical power per core of a two-core multi-core optical amplifier 1100 is 1 [W / core]. The required pump optical power P [W] is the optical power required for the entire multi-core optical amplifier 1100. Therefore, the required pump optical power P is proportional to the power consumption of the multi-core optical amplifier 1100.

[0051] As the number of cores increases, the cladding area per core decreases, and so the pumping density per core increases, as shown in Figure 5. Since the pumping density per core increases as the number of cores increases, the required optical power per core decreases as the number of cores increases. The required pumping optical power P is calculated by multiplying the optical power per core required to generate an excited state by the number of cores.

[0052] Next, an example of the operation of the connection topology determination unit will be described.

[0053] First, we will explain the operation of the connection topology determination unit when the operation mode of the optical amplifier 1000 is a mode that minimizes power consumption. In this case, the connection topology determination unit determines the connection topology between the multi-core optical transmission line 10 and the multi-core optical amplifier 1100 based on information about the configuration of the multi-core optical amplifier 1100 and the following conditions (1) to (3). min[Σ(N k ×P k )] (1) Σ(m k ×N k )≧n (2) N k , m k , n is an integer greater than or equal to 0 (3) Here, "P k ” is the required excitation light intensity, “N k " is the number of multi-core optical amplifier units 1100, and "m k " indicates the number of amplifier cores, and "n" indicates the number of transmission cores. Note that "k" is a variable used to calculate the sum (Σ).

[0054] At this time, the connection topology determination unit determines the number of amplifier cores to be "m k The number of multi-core optical amplifier units 1100 is "N k " is determined. Conditions (1) to (3) involve finding the value that minimizes a certain linear equation among the values ​​of variables that satisfy linear inequalities and linear equalities. Therefore, conditions (1) to (3) can be solved using the widely known linear programming method.

[0055] As a specific example, the number of transmission cores n is 14, and the number of amplification cores m in each of the multi-core optical amplifier units 1101 to 1104 is 1105. k The case where m1=7, m2=7, m3=7, and m4=19 is taken as an example. In this case, the required pumping light intensity P k From Figure 5, [W] is P1=2.1, P2=2.1, P3=2.1, and P4=5.

[0056] In this case, condition (2)Σ(m k ×N k ) ≧ n, k Among them, from condition (1), Σ(N k ×P k ) is minimized. k Substituting the above values ​​into condition (2), condition (2) can be expressed as follows:

[0057] 7×N1+7×N2+7×N3+19×N4≧14 (2-1) Also, the Σ(N k ×P k ) is expressed as follows:

[0058] 2.1×N1+2.1×N2+2.1×N3+5×N4=2.1×(N1+N2+N3)+5×N4(1-1) In the power consumption minimization mode, the required excitation light intensity P kSince we can select the input cores in ascending order of , first let N4 = 0, then equation (2-1) becomes 7 × (N1 + N2 + N3) ≥ 14, that is, N1 + N2 + N3 ≥ 2. Therefore, from equation (1-1), we can find the combination of N1 to N3 that minimizes 2.1 × (N1 + N2 + N3) from among the combinations of N1 to N3 that satisfy N1 + N2 + N3 ≥ 2.

[0059] Here, N1 to N3 represent the numbers of multi-core optical amplifiers 1101 to 1103, each of which has seven amplification cores. Therefore, whether N1=N2=1, N3=0 or N1=0, N2=N3=1, the fact remains that two multi-core optical amplifiers, each with seven amplification cores, are required. In this case, the value of equation (1-1) is 2.1×2=4.2.

[0060] On the other hand, if N4 = 1, it is clear from equation (2-1) that N1 = N2 = N3 = 0. In this case, the value of equation (1-1) becomes 5 × 1 = 5.

[0061] From the above, it can be seen that connecting 14 transmission cores to two 7-core multi-core optical amplifiers consumes less power than connecting them to one 19-core multi-core optical amplifier, with the minimum power consumption being 4.2 W.

[0062] Next, we will explain the operation of the connection topology determination unit when the operation mode of the optical amplifier 1000 is a mode that maximizes the optical amplification degree. In this case, the connection topology determination unit determines the connection topology between the multi-core optical transmission line 10 and the multi-core optical amplification unit 1100 based on information about the configuration of the multi-core optical amplification unit 1100 and the following conditions (4) to (7). max[Σ(N k ×η k )] / ΣN k (4) min[Σ(m k ×N k )-n] (5) Σ(m k ×N k )-n≧0 (6) Nk , m k , n is an integer greater than or equal to 0 (7) At this time, the connection topology determination unit determines the number of amplifier cores to be "m k The number of multi-core optical amplifier units 1100 is "N k " is determined. Conditions (4) to (7) seek the value that minimizes a certain linear equation among the values ​​of variables that satisfy linear inequalities and linear equalities. Therefore, conditions (4) to (7) can be solved using the widely known linear programming method.

[0063] In the following, as in the case of the above-mentioned power consumption minimization mode, the number of transmission cores n=14, and the number of amplification cores m in each of the multi-core optical amplifier units 1101 to 1104 are assumed. k The case where m1=7, m2=7, m3=7, and m4=19 is taken as an example. In this case, the pumping density ratio η for each number of cores in the multi-core optical amplifier units 1101 to 1104 is k From Figure 5, η1 = 3, η2 = 3, η3 = 3, and η4 = 3.8, respectively.

[0064] In this case, condition (6)Σ(m k ×N k )-n≧0, N is the number of multi-core optical amplifier units 1100 k Among them, from condition (4), Σ(N k ×η k )] / ΣN k N that maximizes k Substituting the above values ​​into condition (6), condition (6) can be expressed as follows:

[0065] 7×N1+7×N2+7×N3+19×N4-14≧0 (6-1) Also, the Σ(N k ×η k )] / ΣN k is expressed as follows:

[0066] (3×N1+3×N2+3×N3+3.8×N4) / (N1+N2+N3+N4) =(3×(N1+N2+N3+N4)+0.8×N4) / (N1+N2+N3+N4) (4-1) In the case of the mode that maximizes the optical amplification, the pumping density ratio η k Since we only need to select the core to be input in descending order of N4, we first set N4 = 1. In this case, from equation (6-1) and condition (5), 7×(N1+N2+N3)+5 (6-2) is minimum, and from equation (4-1) 3+0.8 / (N1+N2+N3+1) (4-2) All we need to do is find the combination of N1 to N3 that maximizes the value of (6-2). It is clear that N1 to N3, which minimize equation (6-2), are N1=N2=N3=0. In this case, the value of equation (4-2) is 3+0.8=3.8.

[0067] On the other hand, if N4=0, then conditions (5) and (6) indicate that we need to find the combination of N1 to N3 where 7×(N1+N2+N3)-14 is greater than or equal to 0 and is the smallest. In this case, we can see that it is sufficient if one of N1 to N3 is 0 and the rest are 1. In this case, the value of condition (4) is (1×3+1×3) / (1+1)=3.

[0068] From the above, it can be seen that connecting all 14 transmission cores to one 19-core multi-core optical amplifier unit achieves a higher optical amplification factor than connecting each to two 7-core multi-core optical amplifier units, with the maximum optical amplification factor being 3.8.

[0069] In this way, the connection topology determination unit can determine the connection topology between the multi-core optical transmission line 10 and the multi-core optical amplifier unit 1100 according to the operation mode, using information on the number of transmission cores and the configuration of the multi-core optical amplifier unit 1100. In this case, for example, a network management system (NMS) can specify the operation mode to the optical amplifier device 1000, and the optical amplifier device 1000 can operate in the operation mode requested by the network management system (NMS).

[0070] In addition to the above-mentioned configuration, a network management system (NMS) may determine the connection topology between the multi-core optical transmission line 10 and the multi-core optical amplifier unit 1100 using information on the number of transmission cores and the configuration of the multi-core optical amplifier unit 1100. That is, the network management system (NMS) may be configured to use linear programming to find a solution that satisfies the above conditions (1) to (3) or conditions (4) to (7). In this case, the optical amplifier device 1000 may be configured to have a connection topology accepting unit (connection topology accepting means) that accepts information on the connection topology according to the operation mode.

[0071] Next, the optical amplification method according to this embodiment will be described with reference to the flowchart shown in FIG.

[0072] In the optical amplification method according to this embodiment, a multi-core optical amplifier including a plurality of amplification cores is connected to a multi-core optical transmission line including a plurality of transmission line cores (step S11). k The sum of (Σ(m k ×N k )) are connected so that the number of transmission line cores through which the signal light propagates is equal to or greater than n. Then, the signal light is amplified by these multiple amplification cores (step S12).

[0073] As described above, the optical amplification method of this embodiment is configured to connect a multi-core optical amplifier to a multi-core optical transmission line so that the total number of amplification cores is equal to or greater than the number of transmission cores. Therefore, the optical amplification method of this embodiment makes it possible to connect a multi-core optical transmission line to a multi-core optical amplifier even when the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier.

[0074] Here, connecting the multi-core optical amplifier and the multi-core optical transmission line (step S11) may include switching the connections between the multiple amplification cores and the multiple transmission line cores depending on the operation mode.

[0075] In this case, in the optical amplification method according to the present embodiment, the connection topology is determined according to the operation mode using information on the number of transmission cores and the configuration of the multi-core optical amplifier (step S21).

[0076] Furthermore, amplifying the signal light (step S12) described above may include generating pumping light for pumping a plurality of amplifying cores, branching the pumping light at a branching ratio according to the operation mode, and introducing the branched pumping light into the multi-core optical amplifier by a cladding pumping method.

[0077] As described above, according to the optical amplification device 1000 and optical amplification method of this embodiment, even if the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier, it is possible to connect the multi-core optical transmission line to the multi-core optical amplifier.

[0078] Third Embodiment Next, a third embodiment of the present invention will be described. Fig. 7 shows the configuration of an optical amplifier 2000 according to this embodiment. Note that the same components as those in the optical amplifier 1000 according to the first embodiment are given the same reference numerals, and detailed descriptions thereof may be omitted.

[0079] The optical amplifier device 2000 includes a multi-core optical amplifier section (multi-core optical amplifier means) 1100 and a connection section (connection means) 2200.

[0080] The multi-core optical amplifying unit 1100 includes a plurality of amplification cores. The multi-core optical amplifying unit 1100 may include a plurality of multi-core optical amplifying units with different numbers of amplification cores. Fig. 7 shows, as an example, a configuration including four multi-core optical amplifying units 1101 to 1104.

[0081] The connecting unit 2200 connects the multi-core optical amplifier unit 1100 and the multi-core optical transmission line 10 having a plurality of transmission line cores. As an example, Fig. 7 shows a configuration including a first connecting unit 2210 that connects the multi-core optical transmission line 11 on the input side to the multi-core optical amplifier unit 1100, and a second connecting unit 2220 that connects the multi-core optical transmission line 12 on the output side to the multi-core optical amplifier unit 1100.

[0082] Here, the total number of the multiple amplification cores is equal to or greater than the number of transmission cores through which signal light propagates among the multiple transmission line cores. Therefore, according to the optical amplifying device 2000 of this embodiment, even if the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier, it is possible to connect the multi-core optical transmission line to the multi-core optical amplifier.

[0083] The connection unit 2200 can be configured to connect the multi-core optical amplifier unit 1100 and the multi-core optical transmission line 10 according to the operation mode of the optical amplifier device 2000. In the optical amplifier device 2000 of this embodiment, the connection unit 2200 is configured to connect multiple amplification cores of the multi-core optical amplifier unit 1100 selected according to the operation mode to multiple transmission line cores.

[0084] The first connecting unit 1210 and the second connecting unit 1220 can be configured to include third fan-in fan-out units (third fan-in fan-out means) 2211, 2221 and fourth fan-in fan-out units (fourth fan-in fan-out means) 2213, 2223, respectively. The third fan-in fan-out units 2211, 2221 connect multiple transmission line cores to single-core optical transmission lines 2212, 2222, respectively. The fourth fan-in fan-out units 2213, 2223 connect the single-core optical transmission lines 2212, 2222 to multiple amplification cores, respectively.

[0085] In this embodiment, a case will be described in which the number of transmission cores in the multi-core optical transmission line 10 is fixed and the operation mode of the optical amplifier 2000 is predetermined. In this case, by using information (parameters) related to the configuration of the multi-core optical amplifier 1100 shown in Fig. 5, the configuration of the multi-core optical amplifier 1100 to be built into the optical amplifier 2000 can be calculated by linear programming as shown in the second embodiment. Here, the configuration of the multi-core optical amplifier 1100 refers to the number of multi-core optical amplifiers 1100 for each number of amplification cores.

[0086] That is, the optical amplifier 2000 according to this embodiment is configured to incorporate the required number of multi-core optical amplifier units 1100 for each number of amplification cores selected according to a predetermined operation mode. Therefore, it is sufficient to install only the minimum number of multi-core optical amplifier units 1100, and there is no need to provide an optical switching unit (optical switch) in the connection unit 2200. Furthermore, the control unit 2500 of the optical amplifier 2000 does not require the connection topology determination unit provided in the control unit 1500 of the optical amplifier 1000 according to the second embodiment. As a result, the optical amplifier 2000 according to this embodiment can significantly reduce manufacturing costs.

[0087] As described above, the optical amplifier 2000 of this embodiment can be manufactured at low cost and can be used in an optical amplifier specialized for a particular application. Specifically, the optical amplifier 2000 can be used in a submarine optical repeater that has a fixed number of input and output transmission cores and operates in a mode that minimizes power consumption.

[0088] Next, the optical amplification method according to this embodiment will be described with reference to the flowchart shown in FIG.

[0089] In the optical amplification method according to this embodiment, a multi-core optical amplifier including a plurality of amplification cores is connected to a multi-core optical transmission line including a plurality of transmission line cores (step S11). k The sum of (Σ(m k ×N k)) are connected so that the number of transmission line cores through which the signal light propagates is equal to or greater than n. Then, the signal light is amplified by these multiple amplification cores (step S12).

[0090] As described above, the optical amplification method of this embodiment is configured to connect a multi-core optical amplifier to a multi-core optical transmission line so that the total number of amplification cores is equal to or greater than the number of transmission cores. Therefore, the optical amplification method of this embodiment makes it possible to connect a multi-core optical transmission line to a multi-core optical amplifier even when the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier.

[0091] Here, connecting the multi-core optical amplifier and the multi-core optical transmission line (step S11) may include connecting the multi-core optical amplifier and the multi-core optical transmission line according to the overall operation mode of the multi-core optical amplifier.

[0092] In this case, in the optical amplification method according to the present embodiment, a multi-core optical amplifier according to the operation mode is selected using information on the number of transmission cores and the configuration of the multi-core optical amplifier (step S31). In this case, connecting the multi-core optical amplifier to the multi-core optical transmission line (step S11) can include connecting the multiple amplification cores of the multi-core optical amplifier selected according to the operation mode to the multiple transmission line cores.

[0093] As described above, the optical amplifier 2000 and optical amplification method of this embodiment make it possible to connect a multi-core optical transmission line to a multi-core optical amplifier even when the number of cores in the multi-core optical transmission line does not match the number of cores in the multi-core optical amplifier. Furthermore, the manufacturing cost of the optical amplifier can be significantly reduced.

[0094] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0095] (Supplementary Note 1) An optical amplification device comprising: a multi-core optical amplification means having a plurality of amplification cores; and a connection means for connecting the multi-core optical amplification means with a multi-core optical transmission line having a plurality of transmission line cores, wherein the total number of the plurality of amplification cores is equal to or greater than the number of transmission cores through which signal light propagates among the plurality of transmission line cores.

[0096] (Supplementary Note 2) The optical amplifying device according to Supplementary Note 1, wherein the multi-core optical amplifying means includes a plurality of multi-core optical amplifying means each having a different number of the plurality of amplification cores.

[0097] (Supplementary Note 3) The optical amplifying device according to Supplementary Note 1 or 2, wherein the connection means connects the multi-core optical amplifying means and the multi-core optical transmission line depending on an operation mode of the optical amplifying device.

[0098] (Supplementary Note 4) The optical amplification device according to Supplementary Note 3, wherein the connection means connects the multi-core optical amplification means and the multi-core optical transmission line in a connection form that minimizes the sum of the excitation light intensities of the multi-core optical amplification means when the operation mode is a mode that minimizes power consumption.

[0099] (Supplementary Note 5) The optical amplifier according to Supplementary Note 4, wherein the pumping light intensity is determined by the configuration of the multi-core optical amplifier means, including the number of the plurality of amplification cores.

[0100] (Supplementary Note 6) The optical amplification device according to Supplementary Note 3, wherein the connection means connects the multi-core optical amplification means and the multi-core optical transmission line in a connection configuration in which the sum of the excitation densities of the multi-core optical amplification means is maximized when the operation mode is a mode that maximizes the optical amplification degree.

[0101] (Supplementary Note 7) The optical amplifier according to Supplementary Note 6, wherein the pumping density is determined by the configuration of the multi-core optical amplifier means, including the number of the plurality of amplification cores.

[0102] (Appendix 8) The optical amplifying device according to any one of Appendices 3 to 7, wherein the connection means switches the connections between the plurality of amplification cores and the plurality of transmission line cores depending on the operation mode.

[0103] (Supplementary Note 9) The optical amplifying device according to Supplementary Note 8, wherein the connection means comprises first fan-in / fan-out means for connecting the plurality of transmission line cores to a first single-core optical transmission line, respectively, optical switching means for switching the connection between the first single-core optical transmission line and a second single-core optical transmission line, and second fan-in / fan-out means for connecting the second single-core optical transmission line to the plurality of amplification cores, respectively.

[0104] (Supplementary Note 10) The optical amplifier according to any one of Supplementary Notes 4 to 9, further comprising a connection topology determination means for determining the connection topology according to the operation mode using information about the number of transmission cores and the configuration of the multi-core optical amplifier means.

[0105] (Supplementary Note 11) The optical amplifier according to any one of Supplementary Notes 4 to 9, comprising a connection configuration receiving means for receiving information about the connection configuration corresponding to the operation mode.

[0106] (Supplementary Note 12) The optical amplifier device according to any one of Supplementary Notes 3 to 7, wherein the connection means connects the plurality of amplification cores of the multi-core optical amplifier means selected according to the operation mode to the plurality of transmission line cores.

[0107] (Supplementary Note 13) The optical amplifying device according to Supplementary Note 12, wherein the connecting means comprises third fan-in fan-out means for connecting the plurality of transmission line cores and a single-core optical transmission line, respectively, and fourth fan-in fan-out means for connecting the single-core optical transmission line and the plurality of amplification cores, respectively.

[0108] (Appendix 14) An optical amplifier device according to any one of Appendices 1 to 13, wherein each of the plurality of amplification cores contains a rare earth ion, and the multi-core optical amplifier means has a double clad structure.

[0109] (Supplementary Note 15) A pumping light introducing means is provided for introducing pumping light for exciting the plurality of amplification cores into the multi-core optical amplifier means by a cladding pumping method, and the pumping light introducing means comprises: 15. The optical amplifier according to claim 3, comprising: a pumping light generating unit that generates the pumping light; a variable branching unit that branches the pumping light and supplies the branched pumping light to the multi-core optical amplifier; and a pumping light control unit that determines a branching ratio of the variable branching unit according to the operation mode and sets the determined branching ratio in the variable branching unit.

[0110] (Appendix 16) An optical amplifier according to appendix 15, wherein the pumping light generating means comprises a plurality of light sources that generate laser light, and a combining means that combines the laser light generated by the plurality of light sources and transmits the pumping light.

[0111] (Supplementary Note 17) An optical amplification method comprising connecting a multi-core optical amplifier having a plurality of amplification cores to a multi-core optical transmission line having a plurality of transmission line cores such that the total number of the plurality of amplification cores is equal to or greater than the number of transmission cores through which signal light propagates among the plurality of transmission line cores, and amplifying the signal light by the plurality of amplification cores.

[0112] (Supplementary Note 18) The optical amplification method according to Supplementary Note 17, wherein connecting the multi-core optical amplifier and the multi-core optical transmission line includes connecting the multi-core optical amplifier and the multi-core optical transmission line according to an overall operation mode of the multi-core optical amplifier.

[0113] (Supplementary Note 19) The optical amplification method according to Supplementary Note 18, wherein connecting the multi-core optical amplifier and the multi-core optical transmission line includes connecting the multi-core optical amplifier and the multi-core optical transmission line in a connection topology that minimizes the sum of the excitation light intensities of the multi-core optical amplifiers when the operation mode is a mode that minimizes power consumption.

[0114] (Supplementary Note 20) The optical amplification method according to Supplementary Note 19, wherein the pumping light intensity is determined by the configuration of the multi-core optical amplifier, including the number of the plurality of amplification cores.

[0115] (Supplementary Note 21) The optical amplification method according to Supplementary Note 18, wherein connecting the multi-core optical amplifier and the multi-core optical transmission line in a connection topology that maximizes the sum of excitation densities of the multi-core optical amplifiers when the operation mode is a mode that maximizes optical amplification.

[0116] (Supplementary Note 22) The optical amplification method according to Supplementary Note 21, wherein the pumping density is determined by the configuration of the multi-core optical amplifier, including the number of the plurality of amplification cores.

[0117] (Supplementary Note 23) The optical amplification method according to any one of Supplementary Notes 18 to 22, wherein connecting the multi-core optical amplifier and the multi-core optical transmission line includes switching connections between the plurality of amplification cores and the plurality of transmission line cores depending on the operation mode.

[0118] (Supplementary Note 24) The optical amplification method according to any one of Supplementary Notes 19 to 22, further comprising determining the connection topology according to the operation mode using information on the number of transmission cores and the configuration of the multi-core optical amplifier.

[0119] (Supplementary Note 25) The optical amplification method according to any one of Supplementary Notes 18 to 22, further comprising selecting the multi-core optical amplifier according to the operation mode using information on the number of transmission cores and the configuration of the multi-core optical amplifier.

[0120] (Supplementary Note 26) The optical amplification method according to Supplementary Note 25, wherein connecting the multi-core optical amplifier and the multi-core optical transmission line includes connecting the plurality of amplification cores of the multi-core optical amplifier selected according to the operation mode to the plurality of transmission line cores.

[0121] (Supplementary Note 27) The optical amplification method according to any one of Supplementary Notes 18 to 26, wherein amplifying the signal light includes generating pumping light for pumping the plurality of amplification cores, branching the pumping light at a branching ratio according to the operation mode, and introducing the branched pumping light into the multi-core optical amplifier by a cladding pumping method.

[0122] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. [Explanation of symbols]

[0123] 100, 1000, 2000 Optical Amplifier 110, 1100, 1101 to 1104 Multi-core optical amplifier 120, 1200, 2200 connection part 1210, 2210 First connection part 1211, 1221 First fan-in / fan-out section 1212, 1222 Optical switching unit 1213, 1223 Second fan-in fan-out section 1220, 2220 Second connection 1300 Excitation light generation unit 1310 light source 1320 Multiplexing section 1330 Driver 1400 Variable Branch 1410 Combiner 1500, 2500 control section 2211, 2221 Third fan-in / fan-out section 2212, 2222 Single-core optical transmission line 2213, 2223 Fourth fan-in fan-out section 10, 11, 12 Multi-core optical transmission line

Claims

1. a multi-core optical amplifier having a plurality of amplification cores for optically amplifying signal light; a connecting means for connecting the multi-core optical amplifying means and a multi-core optical transmission line having a plurality of transmission line cores; and the total number of the plurality of amplification cores is equal to or greater than the number of transmission cores through which the signal light propagates among the plurality of transmission line cores, The plurality of amplification cores and the plurality of transmission line cores selected according to the operation mode of the optical amplifier are connected in advance. Optical amplifier.

2. The multi-core optical amplifier includes a mixture of multiple multi-core fibers having different numbers of amplification cores.

2. An optical amplifier according to claim 1.

3. The operation mode is set based on predetermined required specifications.

3. An optical amplifier according to claim 1 or 2.

4. The multi-core optical amplifier performs optical amplification by cladding pumping of pumping light.

4. An optical amplifier according to claim 1.

5. When the operation mode is low power consumption, the number of the multi-core fibers required for each number of the amplification cores is selected based on the intensity of the pumping light. An optical amplifier according to claim 4 which relies on claim 2.

6. The selection may be so that the sum of the intensities of the pumping lights for each of the plurality of multi-core fibers included in the multi-core optical amplifier means is reduced, This is performed by adjusting the combination of the transmission line core through which the signal light propagates and the plurality of multi-core fibers.

6. An optical amplifier according to claim 5.

7. When the operation mode is a high amplification efficiency mode, the number of the multi-core fibers required for each number of the amplification cores is selected based on the density of the pumping light. An optical amplifier according to claim 4 which relies on claim 2.

8. The selection may be so that the sum of the densities of the pumping lights for each of the plurality of multi-core fibers included in the multi-core optical amplifier means increases, This is performed by adjusting the combination of the transmission line core through which the signal light propagates and the plurality of multi-core fibers.

8. An optical amplifier according to claim 7.

9. the pumping light is branched at a branching ratio according to the operation mode, The branched pumping light is introduced into each of the plurality of multi-core fibers included in the multi-core optical amplifier means.

9. An optical amplifier according to claim 4.

10. the total number of the plurality of amplification cores that perform optical amplification of the signal light is equal to or greater than the number of transmission cores through which the signal light propagates among the plurality of transmission line cores, The plurality of amplification cores using multi-core fibers selected according to the operation mode of the optical amplification are connected in advance to the plurality of transmission line cores using multi-core fibers. Optical amplification method.

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