Transmission device

Abstract

This transmission device includes a plurality of light sources and a control unit. Each of the plurality of light sources outputs feed light to be input to each of a plurality of cores included in a multi-core optical fiber. The control unit controls the plurality of light sources such that the light intensity of the feed light input into some of the cores is changed corresponding to transmission data, and the sum of the light intensities of the feed light input into each of the plurality of cores included in the multi-core optical fiber is a value based on the upper limit value of the amount of energy that can be input into the multi-core optical fiber.

Description

Transmitting device

[0001] The present invention relates to a transmitting device.

[0002] Fig. 13 is a diagram showing the configuration of an optical communication system 900 that performs optical power feeding. The optical communication system 900 performs optical power feeding with the simplest configuration using a multicore fiber (MCF) 101. The MCF 101 is a multicore optical fiber having M cores 102 (M is an integer of 2 or more). Of the M cores 102, the m-th core 102 is referred to as core #m (m is an integer of 1 or more and M or less). Fig. 13 shows an example where M=2.

[0003] The optical communication system 900 includes a transmitting device 910 and equipment 920. The transmitting device 910 is installed in, for example, a station building. The transmitting device 910 is connected to the equipment 920 via an MCF 101. The transmitting device 910 includes light sources 911-1 to 911-M. The transmitting device 910 inputs light output from the light source 911-m into core #m of the MCF 101 to transmit the energy.

[0004] The remote device 920 includes photoelectric converters 921-1 to 921-M, storage batteries 922-1 to 922-M, and a signal processing circuit 923. The light source converter 921-m photoelectrically converts the light from the light source 911-m transmitted through the core #m of the MCF 101, and converts it into electricity. The device 920 operates using the electricity obtained by the photoelectric conversion. For example, the storage battery 922-m stores the electricity obtained by the light source converter 921-m, and the signal processing circuit 923 operates by receiving the supply of electricity stored in the storage batteries 922-1 to 922-M.

[0005] The more light input into the fiber, the more power can be obtained from the device 920. However, the amount of light input into the fiber cannot be increased infinitely. From the viewpoint of safety in the event of fiber breakage and fiber melting due to energy concentration within the fiber, it is necessary to input light so as not to exceed the limit amount specified for the fiber. The upper limit amount of energy that can be input into this fiber is defined as P_max.

[0006] 14 is a diagram showing the optical intensity of the feed light transmitted through each core 102 of the MCF 101 in the optical communication system 900. The optical intensity Pm of the feed light transmitted by core #m corresponds to the optical intensity of the output light from the light source 911-m. FIG. 14(a) shows the optical intensity P1 of the light transmitted by core #1 of the MCF 101, FIG. 14(b) shows the optical intensity P2 of the light transmitted by core #2 of the MCF 101, and FIG. 14(c) shows the sum of the optical intensities of core #1 and #2. The sum of the optical intensities P1 and P2 is equal to the upper limit energy amount P_max.

[0007] 15 is a diagram showing the configuration of an optical communication system 950 in which part of the supply of power light from a transmitter is replaced with data transmission such as control signals in the above-mentioned conventional technology (see, for example, Non-Patent Document 1). In Non-Patent Document 1, energy transmission and data transmission are performed using MCF.

[0008] A transmitting device 960 installed in a central office is connected to equipment 970 via an MCF 101. The transmitting device 960 includes one or more light sources 911 and a transceiver 961. The MCF 101 has at least the same number of cores 102 as the total number of light sources 911 and transceivers 961 included in the transmitting device 960. FIG. 15 shows an example in which the number of light sources 911 included in the transmitting device 960 is one, and the number of cores in the MCF 101 is two. The transmitting device 960 outputs light output by the light source 911 to core #1 of the MCF 101, and outputs the data signal of the optical signal output by the transceiver 961 to core #2 of the MCF 101.

[0009] The device 970 includes one or more photoelectric converters 921, one or more storage batteries 922, a signal processing circuit 923, and a transceiver 971. The device 970 includes the same number of photoelectric converters 921 and storage batteries 922 as the number of light sources 911 included in the transmitting device 960. In FIG. 15 , there is one photoelectric converter 921 and one storage battery 922. The photoelectric converter 921 photoelectrically converts light transmitted by core #1 of the MCF 101 and stores the resulting power in the storage battery 922. The transceiver 971 converts a data signal transmitted by core #2 of the MCF 101 from an optical signal to an electrical signal and outputs the electrical signal to the signal processing circuit 923. The signal processing circuit 923 operates by receiving power from the storage battery 922.

[0010] 16A and 16B are diagrams showing the optical intensities of the feed light transmitted through each core 102 of the MCF 101 in the optical communication system 950. Fig. 16A shows the waveform of the optical intensity P1 of the light transmitted through core #1 of the MCF 101, Fig. 16B shows the waveform of the optical intensity P2 of the light transmitted through core #2 of the MCF 101, and Fig. 16C shows the sum of the optical intensities of core #1 and core #2.

[0011] The optical communication system 950 uses a portion of the upper limit energy amount P_max that can be input to the fiber for data transmission. Light with an optical intensity P1 output from the light source 911 is input to core #1. An optical data signal with an optical intensity P2 output from the transceiver 961 is input to core #2. This results in a lower power supply efficiency than the conventional optical communication system 900 shown in FIG. 13. As shown in FIG. 14, the amount of energy supply in the optical communication system 900 is P_max, but as shown in FIG. 16, the amount of energy supply in the optical communication system 950 is reduced to P_max - max(P2). Here, "max(xxx)" means the maximum value of the waveform xxx.

[0012] The processing of the optical communication system 950 will be described below. Here, an example will be described in which the transmitting device 960 has M-1 light sources 911, that is, light source #1 to light source #(M-1), and the device 970 has (M-1) photoelectric converters 921, that is, photoelectric converter #1 to photoelectric converter #(M-1), and (M-1) storage batteries 922, that is, storage battery #1 to storage battery #(M-1).

[0013] 17 is a flow diagram showing the data transmission operation of the transmitting device 960. When data to be transmitted to the device 970 occurs, the transmitting device 960 performs the process shown in FIG. 17. The transceiver 961 of the transmitting device 960 outputs transmission data of an optical signal to the core #M of the MCF 101 (step S901). In parallel, the transmitting device 960 causes the power supply light source 911#k (k is an integer between 1 and M-1) to emit light at an intensity P_core and input the light to the core #k of the MCF 101 (steps S902-1 to S902-(M-1)). P_core is calculated using the following equation (1):

[0014] P_core=(P_max-P_cont_max) / (N_core-1)...(1)

[0015] P_core is the average amount of energy input to each core 102 of the MCF 101. P_max is the total power that can be input to the entire MCF 101. P_cont_max is the maximum optical energy when sending transmission data by core #M. N_core is the number M of cores in the MCF 101.

[0016] As a result, transmission data and optical power supply are performed from the transmitter 960 in the station to the device 970 (step S903).

[0017] In the device 970, each photoelectric converter #k, where k=1 to (M−1), converts the power supply light transmitted through the core #k of the MCF 101 into electric power, and the storage battery #k stores the electric power converted by the photoelectric converter #k. The storage battery #1 to storage battery #(M−1) supply the stored electric power to the signal processing circuit 923.

[0018] 18 is a flow diagram showing the data reception operation of the device 970. The transceiver 971 of the device 970 determines whether transmission data has arrived from core #M of the MCF 101 (step S911). If the transceiver 971 determines that transmission data has not arrived (step S911: NO), it repeats the processing of step S911. If the transceiver 971 determines that transmission data has arrived (step S911: YES), it converts the arrived transmission data from an optical signal to an electrical signal and outputs it to the signal processing circuit 923. The signal processing circuit 923 acquires the transmission data (step S912).

[0019] GKM Hasanuzzaman, Stavros Iezekiel, "Multi-core Fiber Based Mm-wave Generation, Radio-over-Fiber, and Power-over-Fiber", IEEE, 2018 11th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP), 2018

[0020] As mentioned above, when data transmission and optical power feeding are performed simultaneously using an MCF, part of the maximum energy amount P_max that can be input to the fiber is used for data transmission, which reduces the power feeding efficiency. Furthermore, it is necessary to provide a new transceiver or the like in the receiving device. This results in issues such as increased costs for preparing the equipment and increased power consumption.

[0021] In view of the above circumstances, an object of the present invention is to provide a transmitting device that can transmit data without reducing power supply efficiency.

[0022] A transmitting device according to one aspect of the present invention includes a plurality of light sources that output feeding light to be input to each of a plurality of cores in a multi-core optical fiber, and a control unit that changes the optical intensity of the feeding light input to some of the cores in accordance with transmission data and controls the plurality of light sources so that the sum of the optical intensities of the feeding light input to each of the plurality of cores in the multi-core optical fiber becomes a value based on an upper limit of the amount of energy that can be input to the multi-core optical fiber.

[0023] According to the present invention, data transmission can be performed without reducing power supply efficiency.

[0024] FIG. 1 is a configuration diagram of an optical communication system according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating the optical intensity of each core according to the first embodiment. FIG. 3 is a diagram illustrating the optical intensity of each core according to the second embodiment. FIG. 4 is a diagram illustrating the optical intensity of each core according to the third embodiment. FIG. 5 is a diagram illustrating the processing flow of a transmitting device according to the third embodiment. FIG. 6 is a diagram illustrating the processing flow of a transmitting device according to the third embodiment. FIG. 7 is a diagram illustrating the processing flow of equipment according to the third embodiment. FIG. 8 is a configuration diagram of an optical communication system according to a fourth embodiment. FIG. 9 is a diagram illustrating the optical intensity of each core according to the fourth embodiment. FIG. 10 is a diagram illustrating the hardware configuration of a transmitting device according to the first to fourth embodiments. FIG. 11 is a diagram illustrating the configuration of an optical communication system according to the prior art. FIG. 12 is a diagram illustrating the optical intensity of each core according to the prior art. FIG. 13 is a diagram illustrating the optical intensity of each core according to the prior art. FIG. 14 is a flowchart illustrating the data transmission operation of a transmitting device according to the prior art. FIG. 15 is a flowchart illustrating the data reception operation of equipment according to the prior art.

[0025] Embodiments of the present invention will be described in detail below with reference to the drawings. An optical communication system according to the present embodiment simultaneously transmits data and supplies optical power using an MCF. A transmitter in the optical communication system according to the present embodiment changes the intensity of a first supply light beam incident on a first core of the MCF in accordance with the transmitted data, and changes the intensity of a second supply light beam incident on a second core of the MCF so that the sum of the intensity of the first supply light beam and the intensity of the second supply light beam is constant. This enables the optical communication system to transmit data without reducing power supply efficiency. Note that the transmitter may output multiple pairs of first and second supply light beams. Furthermore, multiple second supply light beams may be provided for one first supply light beam. Each embodiment will be described below.

[0026] First Embodiment In the first embodiment, a transmitting device has two light sources.

[0027] 1 is a diagram showing the configuration of an optical communication system 100 according to the first embodiment. The optical communication system 100 includes a transmitting device 110 and an apparatus 120 connected by an MCF 101. The apparatus 120 is an example of a receiving device. The MCF 101 is a multi-core optical fiber having M cores 102. In the first embodiment, M=2. The mth core 102 (m is an integer between 1 and M) is referred to as core #m.

[0028] The transmitting device 110 is installed in, for example, a station building. The transmitting device 110 has a control unit 111 and M light sources 112. The M light sources 112 are respectively referred to as light sources 112-1 to 112-M. The control unit 111 controls the amplitude of the feed light of each light source 112. The light source 112-m outputs the feed light, the amplitude of which has been changed according to the control of the control unit 111, to the core #m of the MCF 101. Note that each light source 112 may also have a control unit having the function of the control unit 111 that controls that light source 112.

[0029] The device 120 has M photoelectric converters 121, M storage batteries 122, and a signal processing circuit 124. The M photoelectric converters 121 are respectively referred to as photoelectric converters 121-1 to 121-M, and the M storage batteries 122 are respectively referred to as storage batteries 122-1 to 122-M. The device 120 may be the device 920 shown in FIG. 13 .

[0030] The photoelectric converter 121-m converts the power supply light transmitted through the core #m of the MCF 101 into electric power. The storage battery 122-m stores the electric power converted by the photoelectric converter 121-m and supplies the stored electric power to the signal processing circuit 124. The storage battery 122 has a measurement unit 123. The measurement unit 123 of the storage battery 122-m will be referred to as the measurement unit 123-m. The measurement unit 123-m is a measurement device that measures the energy input to the storage battery 122-m. The energy to be measured is, for example, the input voltage or the input power.

[0031] The signal processing circuit 124 is realized by a processor such as a CPU (central processing unit) reading and executing a program from a storage unit. All or part of the functions of the signal processing circuit 124 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The signal processing circuit 124 performs signal processing based on the input voltage or input power measured by the measurement unit 123.

[0032] Next, the operation of the optical communication system 100 will be described with reference to Figures 1 and 2. Figure 2 is a diagram showing the optical intensity in each core of the optical communication system 100. Figure 2(a) shows the waveform of the optical intensity P1 of the light transmitted by core #1, Figure 2(b) shows the waveform of the optical intensity P2 of the light transmitted by core #2, and Figure 2(c) shows the sum of the optical intensity P1 of core #1 and the optical intensity P2 of core #2.

[0033] The control unit 111 of the transmitting device 110 receives data D, which is binary information using 0 and 1. The control unit 111 time-varying the amplitude of the optical feed that the light source 112-1 outputs to the core #1 so as to correspond to the data D to be transmitted. In other words, the data D to be transmitted is expressed by the amplitude of the optical feed that the light source 112-1 outputs, i.e., the optical intensity P1.

[0034] Furthermore, the control unit 111 controls the amplitude of the power supply light output from the light source 112-2 to core #2 so that it has the inverse characteristics of the amplitude of the power supply light output to core #1. That is, the control unit 111 controls the sum of the light intensity P1 of the power supply light output from the light source 112-1 and the light intensity P2 of the power supply light output from the light source 112-2 so that it becomes a constant value of the upper limit energy amount P_max that can be input to the fiber. Note that the control unit 111 may also control the sum of the light intensity P1 and the light intensity P2 so that it is equal to or less than the upper limit energy amount P_max. For example, the control unit 111 may control the sum of the light intensity P1 and the light intensity P2 so that it becomes a value that is lower than the upper limit energy amount P_max by a predetermined margin value. The margin value is an arbitrary real value that is set in advance from the viewpoint of safety, etc.

[0035] For example, the control unit 111 controls the light intensity P1 output by the light source 112-1 so that the light intensity is q0 when the transmission bit of data D is 0, and the light intensity is q1 when the transmission bit of data D is 1. q0<q1 or q0>q1 may be satisfied. On the other hand, the control unit 111 controls the light intensity P1 so that when the light intensity of the power supply light from the light source 112-1 is q0, the light intensity of the power supply light from the light source 112-2 is P_max-q0, and when the light intensity of the power supply light from the light source 112-1 is q1, the light intensity of the power supply light from the light source 112-2 is P_max-q1.

[0036] The photoelectric converter 121-1 of the device 120 converts the power supply light transmitted through core #1 of the MCF 101 into electric power, and the storage battery 122-1 stores the electric power converted by the photoelectric converter 121-1. The photoelectric converter 121-2 converts the power supply light transmitted through core #2 of the MCF 101 into electric power, and the storage battery 122-2 stores the electric power converted by the photoelectric converter 121-2. The storage batteries 122-1 and 122-2 supply electric power to the signal processing circuit 124.

[0037] The device 120 reads data D represented by the power supply light transmitted through core #1. Any method for reading this data may be used. Generally, a storage battery is equipped with a mechanism for measuring its input voltage or input current, such as a voltmeter or ammeter. This mechanism is used as the measurement unit 123. The input voltage or input power measured by the measurement unit 123 can detect time fluctuations in the amplitude of the optical signal. This is because the magnitude of the measured value of the input voltage or input power sensed by the measurement unit 123 corresponds to the data D transmitted by the transmitting device 110. Therefore, the device 120 can easily acquire the transmission data by utilizing the existing storage battery mechanism. That is, the signal processing circuit 124 acquires information on the magnitude of the measured value of the input voltage or input power sensed by the measurement unit 123-1 of the storage battery 122-1, and restores the transmission data based on the acquired information.

[0038] If the storage battery 122 does not have a measuring unit 123, a voltmeter that measures the input voltage to the storage battery 122 or an ammeter that measures the input power to the storage battery 122 is provided outside the storage battery 122 as the measuring unit 123.

[0039] According to the first embodiment described above, by associating the optical intensity of a first of the two light sources of the transmitting device with transmission data and making the optical intensity of the second light source have characteristics opposite to those of the optical intensity of the first light source, it is possible to transmit transmission data without exceeding the specified upper limit of fiber input (P_max) while realizing a total power supply amount equivalent to that of the conventional optical communication system shown in FIG. 13 .

[0040] According to the embodiment described above, in a system that simultaneously performs data transmission and optical power feeding using a multicore fiber, data signals can be transmitted with a simple configuration that does not use a transceiver, without reducing power feeding efficiency.

[0041] (Second Embodiment) The first embodiment is a case where the MCF has two cores and one type of data is transmitted. The second embodiment is a case where multiple types of data are transmitted. Here, a case where the number of cores in the MCF is M and the number of types of data is N (M≧2N, N is an integer equal to or greater than 2) is described. The M light sources provided in the transmitting device are designated as light source #1 to light source #M. In this case, light source #1 and light source #2, light source #3 and light source #4, ..., light source #(M−1) and light source #M are each considered to be pairs. The transmitting device associates the optical intensity of one light source of the pair with the transmission data, and sets the optical intensity of the other light source of the pair to have the inverse characteristics of the optical intensity of the light source that is the other light source of the pair.

[0042] Fig. 3 is a diagram showing the configuration of an optical communication system 200 according to the second embodiment. In Fig. 3, the same components as those in the optical communication system 100 according to the first embodiment shown in Fig. 1 are denoted by the same reference numerals, and their description will be omitted. The optical communication system 200 has a transmitting device 210 and a device 220 connected by an MCF 101. Here, the case where M = 2N will be described as an example.

[0043] The transmitting device 210 is installed in, for example, a station building. The transmitting device 210 includes a control unit 211 and light sources 112-1 to 112-M. The control unit 211 controls the amplitude of the power supply light of each light source 112. The light source 112-m outputs the power supply light, the amplitude of which has been changed in accordance with the control of the control unit 211, to core #m of the MCF 101.

[0044] The device 220 includes photoelectric converters 121-1 to 121-M, storage batteries 122-1 to 122-M, and a signal processing circuit 124. The photoelectric converter 121-m converts the power supply light transmitted through core #m of the MCF 101 into electric power. The storage battery 122-m stores the electric power converted by the photoelectric converter 121-m and supplies the stored electric power to the signal processing circuit 124. The signal processing circuit 124 acquires information about the input voltage or input power from a measurement unit 123-m of the storage battery 122-m connected to the photoelectric converter 121-m that has received the power supply light whose optical intensity has been controlled based on the transmission data, and performs signal processing based on the acquired information.

[0045] Next, the operation of the optical communication system 200 will be described with reference to Figures 3 and 4. Figure 4 is a diagram showing the optical intensity in each core of the optical communication system 200. Figure 4(a) shows the waveform of the optical intensity P1 of the light transmitted by core #1, Figure 4(b) shows the waveform of the optical intensity P2 of the light transmitted by core #2, Figure 4(c) shows the waveform of the optical intensity P3 of the light transmitted by core #3, and Figure 4(d) shows the waveform of the optical intensity P4 of the light transmitted by core #4.

[0046] The control unit 211 of the transmitting device 210 receives data D1 to data DN, which are binary information using 0 and 1. The control unit 211 time-varying the amplitude of the optical feed output from the light source 112-(2n-1) to the core #(2n-1) so that the amplitude corresponds to the bit value of 0 or 1 in the data Dn (n is an integer between 1 and N) to be transmitted. In other words, the data Dn to be transmitted is expressed by the amplitude of the optical feed output from the light source 112-(2n-1), i.e., the optical intensity P(2n-1).

[0047] Furthermore, the control unit 211 controls the amplitude of the power supply light output from the light source 112-2n to core #2n so that it has the inverse characteristics of the amplitude of the power supply light output to core #(2n-1). That is, the control unit 211 controls the sum of the amplitude of the power supply light output from the light source 112-(2n-1) and the amplitude of the power supply light output from the light source 112-2n so that it becomes a constant amplitude. As a result, the sum of the light intensity P(2n-1) of the power supply light output from the light source 112-(2n-1) and the light intensity P(2n) of the power supply light output from the light source 112-2n becomes a constant value. Then, the control unit 211 controls the sum of the light intensities P1 to PM so that it becomes a constant value of the upper limit energy amount P_max that can be input to the fiber.

[0048] In addition, when M>2N, the light intensity of each of the light sources 112-m where m=2N+1 to M can be set arbitrarily within the range of energy that can be input to the core #m, under the condition that the sum of the light intensities P1 to PM is a constant value of the upper limit energy amount P_max. Furthermore, the control unit 211 may control the sum of the light intensities P1 to PM so that it is equal to or less than the upper limit energy amount P_max. For example, the control unit 211 may control the sum of the light intensities P1 to PM so that it is a value that is lower than the upper limit energy amount P_max by a predetermined margin value.

[0049] Each photoelectric converter 121-m of the device 220 converts the power supply light transmitted through core #m of the MCF 101 into electrical power. Each storage battery 122-m stores the electrical power converted by the photoelectric converter 121-m. The storage batteries 122-1 to 122-M supply electrical power to the signal processing circuit 124. The signal processing circuit 124 acquires information on the magnitude of the measured values ​​of the input voltage or input power sensed by each measurement unit 123-(2n-1), and restores data Dn based on the acquired information.

[0050] According to the second embodiment, it is possible to realize a total power supply amount equivalent to that of the conventional configuration, and to transmit a plurality of data items while keeping the total power supply amount below the specified upper limit of fiber input (P_max).

[0051] In the first and second embodiments, the addition of the optical feeds in two cores is controlled to produce a flat amplitude. In the third embodiment, the addition of the optical feeds in three or more cores is controlled to produce a flat amplitude.

[0052] Fig. 5 is a diagram showing the configuration of an optical communication system 300 according to the third embodiment. In Fig. 5, the same components as those in the optical communication system 100 according to the first embodiment shown in Fig. 1 and the optical communication system 200 according to the second embodiment shown in Fig. 3 are denoted by the same reference numerals, and their description will be omitted. The optical communication system 300 has a transmitting device 310 and a device 320 connected by an MCF 101.

[0053] The transmitting device 310 is installed in, for example, a station building. The transmitting device 310 includes a control unit 311 and light sources 112-1 to 112-M. In the third embodiment, M is 3 or greater. The control unit 311 changes the amplitude of the feed light output by the light source 112-1 so as to correspond to a bit value of 0 or 1 in the data D to be transmitted. Furthermore, the control unit 311 changes the amplitude of the feed light output by the light sources 112-2 to 112-M so that the sum of the optical intensities of the feed light output by the light sources 112-1 to 112-M becomes the upper limit energy amount P_max.

[0054] The device 320 includes photoelectric converters 121-1 to 121-M, storage batteries 122-1 to 122-M, and a signal processing circuit 124. The photoelectric converter 121-m converts the power supply light transmitted through core #m of the MCF 101 into electric power. The storage battery 122-m stores the electric power converted by the photoelectric converter 121-m and supplies the stored electric power to the signal processing circuit 124. The signal processing circuit 124 acquires information on the input voltage or input power from the measurement unit 123-1 of the storage battery 122-1, and performs signal processing based on the acquired information.

[0055] Next, the operation of the optical communication system 300 will be described using Figures 5 and 6. Figure 6 is a diagram showing the optical intensity in each core of the optical communication system 300. Figure 6 shows an example where M = 3. Figure 6(a) shows the waveform of the optical intensity P1 of the light transmitted by core #1, Figure 6(b) shows the waveform of the optical intensity P2 of the light transmitted by core #2, Figure 6(c) shows the waveform of the optical intensity P3 of the light transmitted by core #3, and Figure 6(d) shows the total value of the optical intensities P1 to P3 of cores #1 to #3, respectively.

[0056] The control unit 311 of the transmitting device 310 receives data D, which is binary information using 0 and 1. The control unit 211 time-varying the amplitude of the optical feed that the light source 112-1 outputs to the core #1 so as to correspond to the bit value of 0 or 1 in the data D to be transmitted. That is, the data D to be transmitted is expressed by the amplitude of the optical feed that the light source 112-1 outputs, i.e., the optical intensity P1.

[0057] Furthermore, the control unit 311 controls the sum of the amplitude of the power supply light output by the light source 112-1 to core #1, the amplitude of the power supply light output by the light source 112-2 to core #2, and the amplitude of the power supply light output by the light source 112-3 to core #3 so that it becomes a constant value (flat). In other words, the control unit 311 controls the sum of the light intensity P1 of the power supply light output by the light source 112-1, the light intensity P2 of the power supply light output by the light source 112-2, and the light intensity P3 of the power supply light output by the light source 112-3 so that it becomes a constant value of the upper limit energy amount P_max. Note that the control unit 311 may also control the sum of the light intensities P1 to P3 so that it becomes a constant value that is lower than the upper limit energy amount P_max by a predetermined margin.

[0058] Each photoelectric converter 121-m of the device 320 converts the power supply light transmitted through core #m of the MCF 101 into electrical power. Each storage battery 122-m stores the electrical power converted by the photoelectric converter 121-m. The storage batteries 122-1 to 122-M supply electrical power to the signal processing circuit 124. The signal processing circuit 124 acquires information on the magnitude of the measured value of the input voltage or input power sensed by the measurement unit 123-1, and restores data D based on the acquired information.

[0059] In addition to the configuration in which the amplitude resulting from adding two optical waveforms is flat, as in the first and second embodiments, the amplitude resulting from adding three optical waveforms may be flattened as shown in FIG. 6 , or, by further extension, the amplitude resulting from adding any number of optical waveforms may be flattened. In addition, in the case of FIG. 6 , the control unit 311 generates the optical waveforms output by the light sources 112-2 and 112-3 so that the sum of the optical waveform transmitted through core #2 and the optical waveform transmitted through core #3 corresponds to "P_max-P1." In this case, the energy distribution ratio between core #2 and core #3 may be arbitrary. As the simplest example, it is conceivable to generate waveforms so that the optical intensity in core #2 and the optical intensity in core #3 are each (P_max-P1) / 2, and equally divide the energy.

[0060] Also, although the above description refers to "flattening" the waveform of the sum of the light in each core (for example, the waveform of P1+P2+P3 in FIG. 6), flattening is not a necessary requirement; it is sufficient that the sum of the waveforms of each core is equal to or less than the upper limit energy amount P_max. For example, as described above, control may be performed so that the sum of the waveforms of each core is a value lower than the upper limit energy amount P_max by a predetermined margin. However, in order to maximize the power supply efficiency, it is necessary to make the sum waveform the same value as P_max, so it is desirable that the sum waveform is flat.

[0061] 7 and 8 are flow diagrams showing the operation of the transmitting device 310. In FIGS. 7 and 8, the light source 112-m included in the transmitting device 310 is referred to as light source #m. The control unit 311 of the transmitting device 310 determines whether there is data to transmit (step S11). If the control unit 311 determines that there is no data to transmit (step S11: NO), it causes light sources #m, m=1 to M, to emit light at an intensity P_core and input the light to core #m of the MCF 101 (steps S12-1 to S12-M). P_core is calculated using the following equation (2):

[0062] P_core=(P_max) / (N_core)...(2)

[0063] P_core is the average amount of energy input to each core 102 of the MCF 101. P_max is the total power that can be input to the entire MCF 101. N_core is the number M of cores in the MCF 101. Note that instead of P_max in equation (2), P_core may be calculated using a value obtained by subtracting a predetermined margin value from P_max.

[0064] As a result, optical power feeding without transmitting data is performed from the transmitting device 310 of the station (step S13). The transmitting device 310 repeats the process from step S11.

[0065] On the other hand, if the control unit 311 determines that there is data to transmit (step S11: YES), it performs the processing of Fig. 8. That is, the control unit 311 determines the time waveform f(t) of light source #1 corresponding to the transmission data to be transmitted (step S21). In the simplest example, the transmission data is converted into a binary number, and when the value is 0, the light intensity is set to q0, and when the value is 1, the light intensity is set to q1, thereby generating a waveform f(t). If the binary number of the transmission data is "01001" and q0<q1, the light intensity strength is "weak strong weak weak strong."

[0066] The control unit 311 calculates a time waveform f'(t) with a flat amplitude by adding the time waveform f(t) determined in step S21 (step S22). Specifically, if a waveform whose intensity does not change over time is designated as A, f'(t) is a time waveform calculated by A-f(t). A may be any value as long as it is within the energy range that can be input to core #m. For example, values ​​such as A = (P_core) or A = 2 x (P_core) can be used.

[0067] The control unit 311 calculates the average energy P_core2 that can be input to the remaining cores using the total amount of energy P_max that can be input to the fiber and the time waveform f(t) and the time waveform f'(t) using the following formula (step S23).

[0068] P_core2={P_max-(f(t)+f'(t))} / (N_core-2)...(3)

[0069] Note that instead of P_max in equation (3), P_core2 may be calculated using a value obtained by subtracting a predetermined margin value from P_max. The control unit 311 controls light source #1 to emit light with a time waveform f(t) and causes the power feed light output from light source #1 to enter core #1 (step S24-1). Concurrently, the control unit 311 controls light source #2 to emit light with a time waveform f'(t) and causes the power feed light output from light source #2 to enter core #2 (step S24-2). Concurrently, the control unit 311 also controls light source #3 to light source #M to emit light with an optical intensity P_core2 and causes the power feed light output from light source #3 to light source #M to enter core #3 to core #M (steps S24-3 to S24-M). This allows optical power feeding carrying transmission data from the transmission device 310 in the central office to the device 320 (step S25). The transmitting device 310 repeats the process from step S11 in FIG.

[0070] 9 is a flow diagram showing the data reception operation of the device 320. The photoelectric converter 121-m, where m=1 to M, converts the power supply light transmitted through the core #m of the MCF 101 into electricity, and the storage battery 122-m stores the electricity converted by the photoelectric converter 121-m. The signal processing circuit 124 determines whether the energy at the input terminal measured by the measurement unit 123-1 of the storage battery 122-1 fluctuates over time by more than a threshold value (step S31). The energy may be, for example, a voltage value or a current value. If the signal processing circuit 124 determines NO in step S31, it repeats the processing of step S31.

[0071] On the other hand, if the signal processing circuit 124 determines in step S31 that the energy at the input terminal measured by the measurement unit 123-1 fluctuates over time by more than the threshold value (step S31: YES), it performs the process of step S32. That is, the signal processing circuit 124 converts the time-varying waveform at the input terminal of the storage battery 124-1 measured by the measurement unit 123-1 into the original transmission data, and obtains the data transmitted from the transmitting device 310 (step S32). The transmitting device 310 repeats the process from step S31.

[0072] Note that L sets (L is an integer of 2 or more) of M sets of light sources 113 in the transmitting device 310 and M sets of photoelectric converters 121 and M sets of storage batteries 122 in the device 320 may be provided. Each set operates in the same manner as described above. In this case, for example, the control unit 311 calculates the value of P_core2 by using (f(t)+f'(t))×L instead of (f(t)+f'(t)) in equation (3) and (N_core-2L) instead of (N_core-2).

[0073] In the first to third embodiments, the amplitude of light transmitted through the cores is controlled to correspond to the bit value 0 or 1 included in the data to be transmitted. In the fourth embodiment, one core is illuminated and the other core is not illuminated to correspond to the bit value 0 or 1 included in the data to be transmitted.

[0074] Fig. 10 is a diagram showing the configuration of an optical communication system 400 according to the fourth embodiment. In Fig. 10, the same components as those in the optical communication system 100 according to the first embodiment shown in Fig. 1 are denoted by the same reference numerals, and their description will be omitted. The optical communication system 400 has a transmitting device 410 and a device 120 connected by an MCF 101.

[0075] The transmitting device 410 is installed in, for example, a central office. The transmitting device 410 includes light sources 112-1 and 112-2 and an optical switch 411. Each light source 112-m generates a feed light of a predetermined optical intensity that is incident on a core #m of the MCF 101. The optical switch 411 switches between the feed light output by the light source 112-1 and the feed light output by the light source 112-2 to be output to the MCF 101 in accordance with data D to be transmitted.

[0076] Next, the operation of the optical communication system 400 will be described with reference to Fig. 10 and Fig. 11. Fig. 11 is a diagram showing the optical intensity in each core of the optical communication system 400. Fig. 11(a) shows the waveform of the optical intensity P1 of the light transmitted by core #1, Fig. 11(b) shows the waveform of the optical intensity P2 of the light transmitted by core #2, and Fig. 11(c) shows the sum of the optical intensity P1 of core #1 and the optical intensity P2 of core #2.

[0077] The optical switch 411 controls which of the light sources 112-1 and 112-2 to turn ON and which to turn OFF, corresponding to each bit value of 0 or 1 in the data D to be transmitted. For example, when the bit value of the data is "1," the optical switch 411 turns ON the switch of the light source 112-1 to emit light and turns OFF the switch of the light source 112-2. When the bit value of the data is "0," the optical switch 411 turns ON the switch of the light source 112-2 to emit light and turns OFF the switch of the light source 112-1. When the switch is ON, the light source 112-1 and the light source 112-2 output power supply light with an optical intensity P_max, and when the switch is OFF, they do not output power supply light (optical intensity 0). As a result, the transmitting device 410 sets the sum of the optical intensity of core #1 and the optical intensity of core #2 to a flat value of P_max.

[0078] When the bit value of the data is "1", the optical switch 411 may operate to pass the power supply light from the light source 112-1 to enter the core #1 and to block the power supply light from the light source 112-2, and when the bit value of the data is "0", the optical switch 411 may operate to pass the power supply light from the light source 112-2 to enter the core #2 and to block the power supply light from the light source 112-1. When the switch is ON, the light source 112 may output power supply light with an optical intensity smaller than P_max.

[0079] According to the above-described embodiment, in an optical communication system using a multi-core optical fiber, the waveform of light transmitted through each core is designed so that the waveform representing the sum of the time waveforms of light transmitted through each core of the multi-core optical fiber does not exceed the maximum energy amount specified for that multi-core optical fiber.

[0080] Furthermore, when optical feed light is input to at least two or more cores of a multi-core optical fiber and the optical feed light input to some of the cores represents transmission data by its amplitude, the optical communication system controls the amplitude of the feed light so that the time waveform representing the sum of the feed light in each core does not exceed a certain value.

[0081] As a method for controlling the amplitude as described above, for example, there is a method in which a first waveform carrying data is created in one optical feed, and the amplitudes of the remaining optical feeds are determined based on information related to the difference between this first waveform and the value of the maximum amount of energy usable in the multi-core optical fiber.

[0082] As described above, as a method for determining the amplitude of the remaining other optical power feeds based on information related to the difference, for example, there is a method for setting the amplitude of optical power feeds that does not include transmission data to an amplitude equivalent to "(amplitude of the first waveform) - (value of the maximum amount of energy that can be used in the multi-core optical fiber) - margin value." The margin value is an arbitrary real value that is set in advance from the viewpoint of safety, etc.

[0083] Furthermore, when the number of cores in a multi-core optical fiber is M (M is an integer of 2 or more) and the number of types of transmission data is N (M≧2N), the N types of transmission data may be represented by feeding light, and the waveforms of the remaining M−N cores may be controlled to make the total waveform of each core of the multi-core optical fiber into a flat shape.

[0084] Furthermore, the receiving device does not use a transceiver, but acquires the data transmitted from the transmitting device based on the measurement result of the power obtained by photoelectric conversion of the feed light transmitted through each core of the multi-core optical fiber. The measurement of the power obtained by photoelectric conversion of the feed light transmitted through each core may be performed using, for example, an energy meter provided in a storage battery that measures the amount of energy such as voltage and power.

[0085] 12 is a diagram showing an example of the hardware configuration of the transmission devices 110, 210, 310, and 410. The transmission devices 110, 210, 310, and 410 each include a processor 701, a storage unit 702, a communication interface 703, and a user interface 704.

[0086] The processor 701 is a central processing unit that performs calculations and control. The processor 701 is, for example, a CPU. The processor 701 reads and executes programs from the storage unit 702. The storage unit 702 further has a work area when the processor 701 executes various programs. The communication interface 703 is connected to other devices so as to be able to communicate with them. The communication interface 703 includes the light source 112. The user interface 704 is an input device such as a keyboard, a pointing device (a mouse, a tablet, etc.), a button, or a touch panel, or a display device such as a display. Human operations are input via the user interface 704.

[0087] At least some of the functions of the control unit 111 of the transmitting device 110, the control unit 211 of the transmitting device 210, the control unit 311 of the transmitting device 310, and the optical switch 411 of the transmitting device 410 are realized by the processor 701 reading and executing a program from the storage unit 702. The programs of the control units 111, 211, 311, and the optical switch 411 may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. The programs of the control units 111, 211, 311, and the optical switch 411 may be transmitted via a telecommunications line. Note that all or some of the functions of the control units 111, 211, 311, and the optical switch 411 may be realized using hardware such as an ASIC, a PLD, or an FPGA.

[0088] According to the above-described embodiment, the transmitting device includes a plurality of light sources and a control unit. Each light source outputs a feed light to be input to each of the plurality of cores of the multi-core optical fiber. The control unit changes the optical intensity of the feed light input to some of the cores in accordance with transmission data, and controls the plurality of light sources so that the sum of the optical intensities of the feed light input to each of the plurality of cores of the multi-core optical fiber becomes a value based on an upper limit value of the amount of energy that can be input to the multi-core optical fiber. The value based on the upper limit value may be the upper limit value of the amount of energy that can be input to the multi-core optical fiber itself, or may be a value that is lower than the upper limit value of the amount of energy that can be input to the multi-core optical fiber by a predetermined value. If the output power of the light source fluctuates over time depending on environmental factors such as temperature, a margin may be provided from the upper limit value of the amount of energy based on the expected amount of fluctuation.

[0089] The control unit may determine the time waveform of the power supply light to be input to some of the cores in accordance with the transmission data, and may determine the time waveform of the power supply light to be input to the cores excluding some of the cores based on the difference between the upper limit value of the amount of energy that can be input to the multi-core optical fiber and the determined time waveform.

[0090] The plurality of light sources may include one or more pairs of a first light source and one or more second light sources. The controller controls, for each pair, the optical intensity of the feed light output by the first light source in accordance with the transmission data, and controls the sum of the optical intensity of the feed light output by the first light source and the optical intensity of the feed light output by the second light source to be a constant value based on an upper limit of the amount of energy that can be input to the multi-core optical fiber.

[0091] Furthermore, a receiving device connected to the transmitting device via the multi-core optical fiber converts the feeding light transmitted through each of the multiple cores of the multi-core optical fiber into electric power, and acquires transmission data based on a measurement result by a measuring device that measures input energy to a storage battery that stores the converted electric power. The transmitting device corresponds to, for example, the devices 120, 220, and 320 of the embodiments.

[0092] The control unit of the transmission device of this embodiment can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0093] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments, and include designs within the scope of the gist of the present invention.

[0094] 100, 200, 300, 400 Optical communication system 101 Multicore fiber 102 Core 110, 210, 310, 410 Transmitting device 111, 211, 311 Control unit 112-1 to 112-M Light source 120, 220, 320 Equipment 121-1 to 121-M Photoelectric converter 122-1 to 122-M Storage battery 123-1 to 123-M Measuring unit 124 Signal processing circuit 411 Optical switch 701 Processor 702 Storage unit 703 Communication interface 704 User interface 900, 950 Optical communication system 910, 960 Transmitting device 911, 911-1 to 911-2 Light source 920, 970 Equipment 921-1 to 921-M Photoelectric converter 922, 922-1 to 922-M Storage battery 923 Signal processing circuit 961, 971 Transceiver

Claims

1. A transmitting device comprising: a plurality of light sources that output optical feed power to be input to each of a plurality of cores of a multi-core optical fiber; and a control unit that changes the optical intensity of the optical feed power input to some of the cores in accordance with transmission data, and controls the plurality of light sources so that the sum of the optical intensities of the optical feed power input to each of the plurality of cores of the multi-core optical fiber becomes a value based on an upper limit of the amount of energy that can be input to the multi-core optical fiber.

2. The transmitting device of claim 1, wherein the control unit determines the time waveform of the power supply light to be input to some of the cores in accordance with the transmission data, and determines the time waveform of the power supply light to be input to cores other than some of the cores based on the difference between the upper limit value and the determined time waveform.

3. The transmitting device described in claim 1, wherein the plurality of light sources include one or more pairs of a first light source and a second light source, and the control unit changes the light intensity of the power supply light output by the first light source for each pair in accordance with the transmission data, and controls the light intensity of the power supply light output by the first light source and the light intensity of the power supply light output by the second light source to be constant values ​​based on the upper limit value.

4. The transmitting device according to claim 1, wherein a receiving device connected to the multi-core optical fiber converts the feeding light transmitted through each of the multiple cores into electric power, and acquires the transmission data based on measurement results from a measuring device that measures input energy to a storage battery that stores the converted electric power.

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