Optical power supply system
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HITACHI LTD
- Filing Date
- 2022-06-24
- Publication Date
- 2026-05-11
Smart Images
Figure 0007856506000001 
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Abstract
Description
Technical Field
[0001] The present invention relates to an optical power supply system, and particularly to an optical power supply technology for performing power transmission using an optical fiber and an optical line test for confirming the soundness of an optical fiber line.
Background Art
[0002] An optical fiber is a medium for transmitting light in a thin glass wire. Because of its extremely low transmission loss of high-frequency signals per unit length compared with an electric cable, it is widely used as a signal transmission medium over a long distance of several meters to several thousand kilometers. The optical power supply dealt with in the present invention is a technology that uses such a communication optical fiber for power transmission. In an optical power supply device on the power transmission side of the optical power supply, a high-output light source such as a semiconductor laser is arranged to convert power into light, input it into an optical fiber, and transmit it. In a power receiving device (hereinafter referred to as a node device in the text), the output light obtained from the optical fiber is received using a photodetector such as a photodiode and converted back into power, and if necessary, it can be used as the operating power of the slave unit by accumulating it.
[0003] When applied to energy transmission, the optical fiber has disadvantages such as a larger transmission loss than an electric cable and a low conversion efficiency (about 20 to 30%) between an optical signal and an electric signal on the power receiving side. Therefore, a large output intensity is required for the optical power supply light source arranged in the master unit, and for example, a high-output semiconductor laser exceeding several hundred milliwatts to 1 W in output is used. However, particularly for a communication optical fiber, the diameter of the central core for transmitting light is as small as several micrometers, and when strong light is incident, the core part melts, so the incident optical power is generally limited to several watts or less.
[0004] Due to these limitations, optical power transmission has a limited range of usable power and is not a widely used technology. However, optical fibers have advantages such as being electrically insulated, highly explosion-proof, less susceptible to electromagnetic interference, and highly corrosion-resistant. Thus, in situations where the use of electrical cables is difficult, or in remote or isolated areas where there are no other suitable power sources, optical power transmission can be used as an effective power transmission technology.
[0005] Furthermore, with optical power supply, optical fibers can be used as a communication medium between the power supply device and multiple node devices, making it advantageous for use in remote areas where radio waves are difficult to reach and wired communication lines are difficult to secure, such as underground, inside buildings, plants, underwater, deserts, mountains, and underground. Actual examples of optical power supply technology use include remote sensing, such as collecting sensing data from infrastructure like pipelines, plants, bridges, and railways, and remote monitoring using cameras.
[0006] Figure 1 is a diagram of a conventional optical power supply system, showing an example of an optical power supply system that supplies power to multiple node devices, as disclosed in Figure 5 of Japanese Patent Publication No. 2021-19444, "Optical Power Supply System" (Patent Document 1). This example is a 1:4 optical power supply system in which four node devices 110-1, 110-2, 110-3, and 110-4 are connected to a single optical power supply device 100 as receiving devices via an optical fiber line 106. Inside the optical power supply device 100, a power supply light source 101 is located and transmits power supply light 104 via the optical fiber line 106. The transmitting unit 102 and the receiving unit 103 are used to send and receive up and down communication light 105 for communication with node devices 110-1 to 110-4 via the optical fiber.
[0007] Although not explicitly stated in this example, multiple optical fiber cores within the optical fiber line 106 may be used to transmit these optical signals, or it is possible to connect to multiple downstream node devices using a single optical fiber core within the optical fiber line 106 by wavelength multiplexing with wavelength differences between them.
[0008] At the end of the optical fiber line 106 are optical splitters (also called optical couplers) 107-1 to 107-3, which each split the power supply light 104 transmitted from upstream at a fixed ratio and distribute it to node devices 110-1 to 110-4, and also play a role in distributing and combining the up and down communication light 105 transmitted and received by each node device. Inside the node devices 110-1 to 110-4 are power receiving units 111-1 to 111-4 that receive the power supply light 104, and convert the received power supply light 104 into electrical energy which is used to operate the node devices 110-1 to 110-4.
[0009] On the other hand, the optical fiber line testing dealt with in this invention is one of the methods for confirming the integrity of optical fiber lines, which is carried out during periodic maintenance or before and after construction work. One of the characteristics of optical fiber lines is that they are relatively resistant to faults and degradation, but they can experience increased loss, communication interruptions, and deterioration of communication quality due to earthquakes, cutting or damage during nearby civil engineering work, or deterioration over time due to damage to the insulation.
[0010] Therefore, depending on the importance of the line, optical line tests such as optical pulse reflection tests (OTDR) and transmission of reference optical signals to measure loss are conducted at regular intervals or before and after construction work to confirm that there are no abnormalities or changes in the loss coefficient, amount of loss, or point of loss occurrence. For this purpose, it is desirable to check the loss and connectivity along the entire length of the optical fiber line between both ends, the upstream and downstream. In the case of OTDR testing, it is possible to perform a reflection test in only one direction by injecting an optical pulse from either the upstream or downstream end of the optical fiber, but in order to accurately determine the optical fiber loss coefficient and to investigate information beyond the point of failure in the event of a break, it is necessary to perform OTDR testing in both directions. [Prior art documents] [Patent Documents]
[0011] [Patent Document 1] Japanese Patent Publication No. 2021-19444 [Overview of the Initiative] [Problems that the invention aims to solve]
[0012] The first problem that this invention aims to solve is that in conventional optical fiber power supply systems, when the optical fiber power supply system is connected to an existing fiber optic line, unused optical fiber sections are created, making optical line testing difficult. This problem will be explained below using Figure 2.
[0013] The optical power supply system requires an optical fiber line for optical power supply and communication between the power supply device 100 and the node device 110. While a dedicated optical fiber line may be laid for this purpose, generally, from the perspective of cost reduction, shortening construction time, and simplification, it is conceivable to utilize existing (or newly constructed) optical fiber lines owned by the company or another company for part of the line. In this diagram, the optical power supply device 100 is located in the central office building 120. An optical fiber cable 123 is laid from relay station 121-1 near the central office building to relay station 121-2, with an optical junction box 124 located along the cable.
[0014] The node device 110 is installed near the optical connection box 124. The endpoints of the optical fiber line 128 in the optical fiber cable 123 (before being cut into two sections 128-1 and 128-2) are housed in optical termination boxes 122-1 and 122-2 installed in the central office 121-1 and central office 121-2. In this example, the optical power supply device 100 is installed close to the relay station 121-1, and in such a case, it is possible to extend the optical fiber from the optical power supply device 100 to the optical connection box 122-1 and connect it to the optical fiber line 128-1 via the optical connector 127-1.
[0015] On the other hand, since there is a distance from the node device 110 to the endpoint of the optical fiber line 128, the optical fiber line is cut inside the optical junction box, and the optical fiber line 128-1 on the optical power supply device 100 side and the extension optical fiber cable 130 to the node device 110 are connected by a splice 131, thereby connecting the optical power supply device 100 and the node device 110 via optical fiber. In this case, the optical fiber line 128-1 is the power supply section used by the optical power supply system, and the optical fiber line 128-2 is an unused section.
[0016] In the example, while line testing can be performed before and after the optical fiber line 126 shown in Figure 2, this is not the case if the optical fiber line 126 is cut and a sensor node is installed in the middle, or if the line is branched off to a line dedicated to optical power supply.
[0017] One challenge with this connection configuration is the difficulty in applying optical line testing between optical fiber lines 128-1 and 128-2. For example, since the two lines are disconnected and non-conductive, it is impossible to perform a loss test of the entire line using a reference light. In the case of optical pulse reflection testing, information can be obtained from the power supply section 128-1 at the endpoint optical connector 127-1 and from the unused section 128-2 at optical connector 127-2. However, it is still not possible to confirm continuity, and since both are unidirectional optical reflection tests, it is not possible to accurately measure the loss coefficient of the optical fiber, which raises concerns that faults or their signs may be overlooked.
[0018] A second challenge is to reduce the man-hours required for line testing and improve the accuracy of understanding the line status. While installing a fiber optic power supply system allows for testing of sections, such as partial optical pulse reflection tests, in the event of disconnections or unused sections of fiber optic lines, it is necessary to understand information such as the presence or absence of node devices and the location of disconnections for each line in advance, and to change the test procedure as needed. This increases the effort required for line testing and reduces its accuracy.
[0019] Therefore, the objective of the present invention is to solve the above problems and provide an optical power supply system that enables optical line testing of optical fiber lines with a simple configuration, thereby improving maintainability and accuracy in understanding the line status. [Means for solving the problem]
[0020] The problem of the present invention can be solved by connecting an optical power supply system in the middle of an optical fiber line, as described above, and configuring the system so that the power supply section and the unused section are optically connected when one section is used for optical power supply and the other is an unused section.
[0021] The power supply system comprises an optical power supply device that emits power supply light, one or more node devices that receive a portion of the power supply light and operate using that power, and first and second geographically separated locations. of The optical fiber line includes a fiber optic line that connects to a third point which is a transit point between the first and second points and connects to an optical power supply device. Of the section between the third point and the first point or the section between the third point and the second point, one is a power supply section used for optical power supply and the other is an unused section, and the power supply section and the unused section are optically connected at the third point of the optical fiber line.
[0022] The aforementioned optical connection can be achieved, for example, by using an optical splitter having three optical ports: a common optical port, a first optical port, and a second optical port. The common optical port is connected to the power supply section of the optical fiber line, the first optical port of the optical splitter is connected to the optical power supply system, and the second optical port is connected to the unused section of the optical fiber line. When using an optical splitter, if the unused section is downstream in the direction of propagation of the power supply light, there is a possibility that the power supply light may leak to the endpoint of the optical fiber line that becomes the unused section. Therefore, it is desirable to perform optical termination processing. Furthermore, the branching of the optical splitter circuit can be easily achieved by setting the optical signal branching ratio output to the second optical port between 50% and 1%.
[0023] In addition, the optical connection can also be realized by using an optical wavelength demultiplexer having three optical ports: a common optical port used for input and output of optical signals in the first and second wavelength bands, a first optical port used for input and output of optical signals in the first wavelength band, and a second optical port used for input and output of optical signals in the second wavelength band. Among these, the common optical port is connected to the power supply section side of the optical fiber line, the first optical port is connected to the optical power supply system, and the second optical port is connected to the unused section side of the optical fiber line. In this case, if the first optical wavelength band is set as the wavelength band of the optical signals transmitted and received by the optical power supply device, and the second wavelength band is used for optical line testing, the feasibility of the present invention is greatly improved.
[0024] As a specific wavelength band allocation, the first wavelength band can be configured to be on the longer wavelength side than 1.4 μm, and the second wavelength band to be on the shorter wavelength side of 1.4 μm or less. Alternatively, the first wavelength band can be on the shorter wavelength side of 1.2 μm or less, and the second wavelength band on the longer wavelength side of 1.2 μm.
[0025] Also, the network topology of the optical power supply device and the node device is not limited to a 1:1 connection. When configured in a multi-stage ladder type configuration in which node devices are sequentially branched and connected using an optical splitter, a star type configuration using an optical star coupler, or a combination thereof, if an unused section occurs in each optical fiber line used, the present invention can be applied by individually arranging the aforementioned optical connection devices.
[0026] Furthermore, in order to perform real-time and centralized management of the line state, in the configuration using the optical wavelength demultiplexer of the present invention, if optical line test devices are arranged on both the upstream side and the downstream side of the optical fiber line, real-time optical line testing can be performed constantly or at regular intervals even during the operation of the optical power supply device, and the obtained line information can be aggregated at the central office.
[0027] Also, when installing the aforementioned optical connection device, it can also be achieved by incorporating the optical connection device inside the optical power supply device or the node device and providing an optical port used for line testing.
Advantages of the Invention
[0028] In one aspect of the present invention, even when a portion of the optical fiber line is used in an optical power supply system, resulting in an unused section, it becomes possible to perform optical line testing between endpoints as in the conventional method. This improves the accuracy of understanding the line status and reduces maintenance man-hours. In particular, it allows for the detection of deterioration and disconnections, including in the unused section, improving the reliability and responsiveness of restoring the line to its original state or changing the wiring, thereby reducing construction costs and downtime.
[0029] When an optical splitter is used in an optical connection device according to one embodiment of the present invention, the above can be achieved in an inexpensive and wavelength-independent configuration, and in this case, safety can be enhanced by performing optical termination processing on the downstream side. Furthermore, the practicality of this configuration can be increased by setting the branching ratio of the optical signal output to the second optical port of the optical branch circuit to between 50% and 1%.
[0030] Furthermore, when an optical wavelength splitter is used in the aforementioned optical connection device, the loss of optical signals used in the optical power supply system, such as the power supply light, and the line test light can be greatly reduced, and the leakage of power supply light downstream can be prevented, improving safety. In particular, when optical pulse reflection testing is used for line testing, the distance resolution does not decrease, and the point of line failure can be accurately detected.
[0031] Furthermore, this invention is applicable to various network configurations and has the effect of saving the number of optical fiber lines and devices. In addition, since the line status can be monitored continuously or periodically even when the optical power supply device is in use, the accuracy of understanding the fault situation is further improved, which has the effect of shortening the fault recovery time and improving reliability.
[0032] Furthermore, by integrating the optical connection device into the optical power supply unit or node unit, it is possible to reduce installation space and construction costs, lower the man-hours required for parts management, and prevent malfunctions. [Brief explanation of the drawing]
[0033] [Figure 1] This is a diagram illustrating the configuration of a conventional optical power supply system. [Figure 2] This is an explanatory diagram illustrating potential problems that may arise in conventional optical power supply systems. [Figure 3] This is a diagram showing a configuration of the first embodiment of the present invention. [Figure 4] This is a diagram showing a second embodiment of the present invention. [Figure 5] This is an explanatory diagram of the optical circuit test in the second embodiment of the present invention. [Figure 6] This is a diagram showing a third embodiment of the present invention. [Figure 7] This is an explanatory diagram of an optical wavelength splitter in a third embodiment of the present invention. [Figure 8] This is a diagram showing a fourth embodiment of the present invention. [Figure 9] This is a diagram showing a fifth embodiment of the present invention. [Figure 10] This is a configuration diagram of a node device in a fifth embodiment of the present invention. [Figure 11] This is a configuration diagram showing a sixth embodiment of the present invention. [Modes for carrying out the invention]
[0034] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. [Examples]
[0035] Figure 3 is a configuration diagram showing an optical power supply system in a first embodiment of the present invention, illustrating a basic embodiment of the present invention. This figure shows an example of a configuration in which two node devices 110-1 and 110-2 are connected in a ladder-like manner to an optical power supply device 100 to provide optical power. Optical connection boxes (generally also called junction boxes or splice boxes) 124-1 and 124-2 are provided in the middle of optical fiber cables 130-1 and 130-2, and the internal optical fiber lines 128 and 129 are cut at cutting points 125-1 and 125-2 respectively, and optical fibers are pulled out from the cut sections and connected to the end of the node devices.
[0036] At the connection point of the upstream node device 110-1, an optical splitter (or optical coupler) 200 is provided to split the power supply light 204 transmitted from the optical fiber line 128-1 into a first branched power supply light 205 and a second branched power supply light 206 at a predetermined splitting ratio. The former is supplied to the node device 110-1, while the latter is returned to the optical fiber line 128-2 and supplied to the downstream node device 110-2.
[0037] The configuration of this section is a standard branching of power supply light, which is also used in conventional optical power supply systems. In this example, although the optical node device 110-1 is installed between optical fiber lines 128-1 and 128-2, both are used as power supply paths to the node device, and therefore do not fall under the unused section of this specification.
[0038] On the other hand, node device 110-2 is the furthest downstream node device, with the optical fiber line 129-1 upstream of the cutting section 125-2 corresponding to the power supply section, and the optical fiber line 129-2 downstream corresponding to the unused section. The optical connection device 201 in the figure is a means for realizing optical connection, supplying the second branch power supply light 206 transmitted via the optical fiber line 129-1 to node device 110-2, and realizing an optical connection between the optical fiber line 129-1 (power supply section) upstream of the cutting section and the optical fiber line 129-2 (unused section) downstream.
[0039] This configuration enables optical fiber line testing, such as unidirectional or bidirectional optical pulse testing and optical loss measurement using a reference light, to be performed between endpoints of an optical fiber line, including the unused optical fiber line 129-2, for example, between optical connector 127-2 and optical connector 127-3, or between optical connector 127-1 and 127-3. Figure 3 shows optical test signals 202-1 and 202-2 as examples of signals for optical testing.
[0040] Although the connection of a conventional optical power supply device using an optical branch coupler 200 and the arrangement using the optical connection device 201 in this embodiment are highly similar in configuration, this optical connection device aims to achieve a new effect by intentionally configuring optical connections in unused sections not used by the optical power supply device, thereby enabling optical fiber line testing between optical endpoints.
[0041] In this specification, the application of this invention is explained using only the power supply light and the optical fiber line used as the path for the power supply light as examples. However, in actual optical power supply systems, it is conceivable that other optical signals or optical fiber lines may be used for upstream and downstream optical communication between the optical power supply device 100 and the node device 110.
[0042] In the case where both the up / down communication light and the power supply light are transmitted by multiplexing them into a single optical fiber using multiplexing technologies such as time-multiplexing or wavelength-multiplexing, the number of optical fiber lines used by the optical power supply system will be only one (number of core wires used in the optical cable = 1), and the configuration shown in this diagram can be applied.
[0043] If multiple optical fiber lines (for example, two or three optical fiber cores) are used within the same optical cable, the present invention can be applied to each optical fiber line to enable the line testing intended by this invention to be performed on all of these optical lines. In this case, strictly speaking, the designation of each optical fiber line may be changed from a power supply section to a communication section, etc., depending on the application.
[0044] Furthermore, although this diagram illustrates a configuration in which optical connection boxes 124-1 and 124-2 are placed in the middle of optical fiber cables 130-1 and 130-2, in reality, optical connection box 124-2 may be configured to connect two physically different optical fiber cables, or the optical connection box may be a connection point for multiple optical fiber cables, connecting the optical fiber cores of different optical fiber cables inside it.
[0045] In reality, installed optical fiber cables are composed of connecting optical fiber cables of a fixed length, such as several hundred meters to several kilometers. Even if an optical fiber cable appears to be a continuous cable in this diagram, it may have multiple connection boxes or connection points along its length, physically connecting different optical fiber cables. Of these connection points, those equipped with optical connectors for easy access during routine maintenance are referred to as optical fiber endpoints in this specification, and are generally housed in optical termination boxes 122 (patch panels, connector boards, etc.) installed within central offices or facilities.
[0046] In some cases, connections may be directly linked to the destination equipment or devices for loss reduction or maintenance reasons, or directly spliced with other lines within the termination box to reduce losses, or the unprocessed ends of optical fibers may be left open as terminal stations. However, these can also be considered endpoints if they are usable during line testing. [Examples]
[0047] Figure 4 is a configuration diagram showing a second embodiment of the present invention, which more specifically illustrates a configuration using the optical splitter 200 as the optical connection device described above. This configuration is an example in which an optical fiber is taken out from an optical connection box 124 installed between optical fiber cables 123-1 and 123-2 and a node device 110 is installed. This node device 110 operates by receiving power from an optical power supply device 100 installed in the upstream central office 120.
[0048] The power supply light 204, although not shown in this figure, passes through several relay stations or optical termination boxes and optical fiber cables before being connected to the optical fiber line 128-1, which is the power supply section, by an optical connector 127-3 inside the optical termination box 122-1 installed at the upstream relay station 121-1. Furthermore, since there are no nodes downstream of the node device 110, the downstream optical fiber line 128-2 is an unused section.
[0049] On the other hand, the optical fiber cables 123-1 and 123-2 also contain other optical fiber lines 126 that are not used in the optical power supply system. In the optical junction box 122, only the optical fiber line 128 is cut into the upstream optical fiber line 128-1, which is the power supply section, and the downstream optical fiber line 128-2, which is the unused section. These are then connected to the common optical port 207 and the second optical port 209 of the optical splitter 200 by splices 133. The remaining first optical port of the optical splitter 200 is connected to the node device 110.
[0050] In this configuration, a certain amount of optical loss occurs between the common optical port 207 and the second optical port 209, depending on the branching ratio of the optical branching circuit to the first optical port and the second optical port. Ideally, the optical loss is approximately 10 dB when using a 9:1 optical brancher and 20 dB when using a 99:1 brancher. Thus, although some loss occurs between the upstream optical fiber line 128-1 and the downstream optical fiber line 128-2, optical connectivity is maintained, making it possible to perform optical line testing between optical endpoints including both, for example, between the upstream optical connector 127-1 and the downstream optical connector 127-4.
[0051] In this case, if the optical branching to the downstream side is made too small, it becomes difficult to distinguish between losses at the optical brancher and losses caused by line faults, and the distance resolution of the optical pulse test deteriorates significantly. The resolution of the optical pulse tester deteriorates to approximately 1m at a loss of 3dB in the measurement section, approximately 5m at 13dB, and 50m at 23dB. Therefore, in order to obtain a realistic resolution, the optical branching ratio must be at least 99:1. In this expression, the "99" in the first term indicates the ratio of branching to the first optical port on the upstream side, and the "1" in the second term indicates the ratio of branching to the second optical port on the downstream side. An optical branching ratio of at least 99:1 indicates that the ratio to the downstream side is greater than or equal to this value.
[0052] On the other hand, the intensity of the power supply light 205 supplied to the node device 110 is also reduced by the branching ratio of the optical splitter 200. The loss of the power supply light 205 is approximately 3 dB when the branching ratio is 1:1 (50% of the power supply light is wasted), approximately 0.5 dB when it is 9:1, and 0.05 dB when it is 99:1. For this reason, the branching ratio when using the optical splitter 200 as an optical connection device is, for example, between 1:1 and 99:1. In other words, the optical signal branching ratio output to the downstream optical port is between 50% and 1%.
[0053] Another problem with this configuration is that, while the optical power supply system is in operation, some of the power supply light is branched to the downstream unused optical fiber line 128-2 and emitted from the optical connector 127-4. Since the light intensity supplied to the node device by optical power supply is very high, ranging from several mW to several hundred mW, even with the branching ratio described above, the intensity of the power supply light 206 leaking to the downstream optical fiber line 128-2 is high, which could lead to burnout accidents inside the optical termination box 122-2 and safety issues for maintenance workers.
[0054] Therefore, in this configuration, it is important to connect the optical termination unit 210 to the optical connector 127-2, which is the endpoint of the unused optical fiber line 128-2 on the downstream side, and to operate in a way that prevents the power supply light 206 from leaking to the outside. When using other optical fiber lines for optical communication or other purposes in this system, the necessity of optical termination for each optical fiber line can be determined on a case-by-case basis depending on the direction and strength of the optical signals transmitted through each optical fiber line.
[0055] In this diagram, the optical splitter 200 is positioned between the node device 110 and the optical junction box 124, but its location and method of placement are arbitrary. For example, it can be housed inside the optical junction box 124 or the node device 110, or it can be installed in a separate enclosure. Furthermore, the connection between the optical junction box 124, the optical splitter 200, and the node device 110 can be wired using optical fiber cables of any length, number of cores, and number of strands as appropriate.
[0056] Figure 5 is an explanatory diagram of an optical circuit test in a second embodiment of the present invention. When performing an optical circuit test on optical fiber circuits 128-1 and 128-2 in this configuration, the optical power supply system is stopped, and the upstream optical test device 211 and the downstream optical test device 212 are connected to the upstream optical connector 127-3 and the downstream optical connector 127-4, respectively. Applicable tests for the optical circuit include tests that evaluate the continuity and loss of the entire optical fiber circuit, such as the unidirectional or bidirectional optical pulse reflection test and optical loss measurement using a reference light as described above.
[0057] In this configuration, loss testing of the entire optical fiber line is possible, as before, including the unused portion of the optical fiber resulting from the installation of the optical power supply device. This ensures the integrity and availability of the optical fiber section 128-2, even when the optical power supply system is removed and optical fiber lines 128-1 and 128-2 are reconnected for restoration, or when the optical power supply system is extended further downstream using the unused optical fiber line 128-2.
[0058] Furthermore, when nearby construction work is carried out, such as installing new equipment on other optical fiber lines 126 within the same optical fiber cable, the integrity of optical fiber lines 128-1 and 128-2 can be confirmed by performing line tests using the same procedure from the same optical termination boxes 122-1 and 122-2 as the other lines. This makes it possible to identify and immediately restore any line failures in unused sections caused by the construction work. [Examples]
[0059] Figure 6 is a configuration diagram showing a third embodiment of the present invention, which is an example in which an optical wavelength splitter (or optical wavelength coupler) is used as the optical connection device, and is configured to maintain connectivity in the unused portion of the optical fiber line at a wavelength different from the wavelength used by the optical power supply system, thereby enabling optical line testing.
[0060] Figure 7 is an explanatory diagram of the optical wavelength splitter 200, which has three optical ports: a common optical port 221, a first optical port 222 that inputs and outputs light in the wavelength range λp, and a second optical port that inputs and outputs light in the wavelength range λc. The optical signals input and output from the common optical port 221 can be separated by wavelength range and input and output from either of the two optical ports 222 or 223. Hereafter, in this specification, the wavelength range λp will be defined as the wavelength range of the power supply light, and the wavelength range λc will be defined as the wavelength range for optical line testing.
[0061] In Figure 6, the power supply light 204 (wavelength range λp) output from the optical power supply device 100 passes through the optical fiber line 128-1, is input to the optical wavelength splitter 220 from the common optical port 221, and then output from the first optical port 222 to be supplied to the node device 110. In this configuration, due to the characteristics of the wavelength splitter, leakage of the power supply light in wavelength range λp to the second optical port is almost zero, which has the advantage of being able to reduce the branching loss of the power supply light toward the node device to an extremely small level compared to the second embodiment described above. In addition, the intensity of the power supply light leaking from the downstream optical connector 127-4 during operation of the optical power supply system can be reduced to almost zero, improving safety, and also eliminating the need for the aforementioned optical terminator.
[0062] Furthermore, since there is conductivity between optical fiber lines 128-1 and 128-2 in the wavelength range λc, optical line tests such as optical pulse tests and optical loss measurements can be performed between the upstream optical connector 127-3 and the downstream optical connector 127-4 by using the wavelength range λc.
[0063] In the above explanation, the wavelength range λp is defined as the wavelength range of the power supply light. However, if the optical power supply system also uses optical signals for uplink and downlink communication, including these optical signals within the wavelength range λp will allow the paths of the power supply light and the uplink and downlink communication light to be aligned, enabling the optical signals between the optical power supply device and the node device to be connected collectively.
[0064] As an example of wavelength allocation, if a 1.48 μm band light source is used for the power supply light as wavelength range λp, it is possible to allocate 1.5 μm or 1.6 μm bands for the up and down communication light, and 1.3 μm band as wavelength range λc. In this case, by setting wavelength range λp to the 1.48-1.6 μm range and wavelength range λc to the 1.3 μm band, a long-distance splitter can be easily realized. Such wavelength allocation is easy to implement because commercially available optical pulse test equipment generally has light sources in the 1.3 μm and 1.5 μm bands. Furthermore, the 1.48-1.5 μm range has advantages such as low optical fiber loss, making it easy to construct long-distance optical power supply systems, and the availability of high-performance wavelength splitters because these wavelength bands are widely used in commercial optical communications.
[0065] When performing wavelength allocation as described above, it is effective to use the optical wavelength splitter with wavelengths longer than 1.4 μm for the optical power supply system and the shorter wavelengths (1.4 μm or less) for line testing. Another possible embodiment is a system configuration that uses visible light or near-infrared light, which has high photoelectric conversion efficiency, as the power supply light. In such a case, it is effective to use the shorter wavelengths (1.2 μm or less) for the optical power supply system and the longer wavelengths (1.2 μm or more) for optical line testing.
[0066] Although not explicitly stated in this application, when multiple optical fibers are used to connect the optical power supply device and the node device, the present invention can be applied individually to each optical fiber line used by the power supply light, up / down communication light, etc., and line testing can be performed by maintaining the optical connection between the power supply section and the unused section. The optical connection devices used in this case do not all need to be the same; it is possible to select different devices depending on the wavelength and characteristics of the optical signal transmitted through the optical fiber.
[0067] For example, from the standpoint of reducing power supply loss and preventing light leakage to downstream lines, the use of wavelength splitter couplers is advantageous for optical connections in optical fiber lines used for transmitting power supply light. Furthermore, when applied to optical fiber lines used for upstream and downstream communication where these effects are less significant, using optical splitters is less likely to cause problems. [Examples]
[0068] Figure 8 is a configuration diagram showing a fourth embodiment of the present invention, in which an optical star coupler 230 is connected to one power supply device 100 to split the power supply optical fiber 104-2 into two, and two node devices 110-1 and 110-2 are connected in a star configuration. In this example, it is assumed that there is no existing optical fiber line connected to the central office 120 where the power supply device 100 is located, and that an extension optical fiber line 130 is installed to connect from the middle of a commercial optical fiber line 128 of a nearby telecommunications carrier. In this figure, the connection point is the optical junction box 124-1 located in the middle of optical fiber lines 128-1 and 128-2, and in this configuration, optical fiber line 128-1 is an unused section and 128-2 is a power supply section.
[0069] In order to enable conventional optical line testing even with the unused optical fiber line 128-1 that has occurred as described above, in this embodiment, an optical branching circuit 200-1 is placed inside the optical connection box 124-1, optically connecting optical fiber lines 128-1 and 128-2 for optical testing, and also connecting optical fiber lines 128-3 and 128-1 as an optical path for power supply light. This makes it possible to perform line testing between optical fiber lines 128-1 and 128-2 between optical termination boxes 122-1 and 122-2 as before.
[0070] As in this example, the unused optical fiber line 128-1, which is generated by the introduction of the power supply light, is oriented in the opposite direction to the direction of travel of the power supply light, so no high-intensity leakage light from the power supply light occurs. For this reason, it is not always necessary to perform optical termination on the optical connector 127-1. Alternatively, instead of the optical splitter 200-1, an optical wavelength splitter may be used as in the example above to maintain optical connectivity for line testing between optical fiber lines 128-1 and 128-2 in a wavelength range λc different from the power supply light wavelength range λp.
[0071] The power supply light 104-2, which passes through the optical fiber line 128-2 and is input to the optical star coupler 230, is split into two branches and distributed to two node devices 110-1 and 110-2 installed near the optical relay boxes 124-2 and 124-3, respectively. When these node devices are installed, the optical fiber line is disconnected in each case, and optical fiber lines 129-2 and 129-4 in Figure 8 become unused sections.
[0072] In this star configuration, unused sections may occur in each branched optical fiber line, but by applying the present invention individually to each section, optical line testing can be performed. In this figure, the optical branching circuit 200-2 is positioned to optically connect the severed optical fiber lines 128-1 and 128-2, and the wavelength splitter 220 is positioned to realize an optical connection between the severed optical fiber lines 129-3 and 129-4.
[0073] Optical fiber line testing can be performed, for example, between optical connectors 127-1 and 127-2 for optical fiber lines 128-1 and 128-2, between optical connectors 127-3 and 127-5 for optical fiber lines 129-1 and 129-2, and between optical connectors 127-4 and 127-6 for optical fiber lines 129-3 and 129-4, thereby confirming the integrity of all optical fiber lines used in this system.
[0074] In this example, the number of branches in the star coupler is set to 2, but there is no problem in further increasing the number of branches. If there is sufficient power supply light, the present invention can be applied to any network configuration, such as by equipping each node device 110-1 and 110-2 with an optical splitter to further split the power supply light and connecting the node devices in cascade. In any case, if an unused section occurs due to the disconnection of the optical fiber line when connecting the upstream optical power supply device or the node device at the end of each branch, an optical connection device can be placed as in this example each time. In this example, optical splitters and optical wavelength splitters were used together as optical connection devices in this embodiment, but they can all be of the same type, or selected as appropriate according to characteristics such as loss and light reflection, and the necessity.
[0075] Furthermore, the location of the optical star coupler 230 is not limited to the optical termination box 122; it may be built into the optical power supply device 100, placed in the optical connection box 124, or directly placed as an independent component inside the central office building 120 or at the branching point of the optical cable. In any case, it is desirable to provide an optical connector as appropriate and house it in an easily accessible optical termination box so that optical line testing can be easily performed. [Examples]
[0076] Figure 9 shows a fifth embodiment of the present invention, which is a drop-type network configuration example in which an existing optical fiber cable 123 is branched off into a separate path consisting of extension optical fiber cables 130-1 to 130-3 dedicated to this system, with three node devices 110-1 to 133 placed along the way.
[0077] In this configuration, within the optical connection box 124-1 that branches the drop path, the existing optical fiber line 128 is divided into an upstream optical fiber line 128-1 which is the power supply section and a downstream optical fiber line 128-2 which is the unused section. In this figure, an optical wavelength splitter 220-1 is placed between them, and the configuration is such that the optical connection between optical fiber lines 128-1 and 128-2 is maintained in the optical test wavelength range λc, and the power supply light 204-1 is rerouted to the optical fiber line 129 inside the extension optical cable 130-1 which is the drop path.
[0078] In a drop-type network configuration like the one shown in this diagram, using an optical splitter instead of the optical wavelength splitter 220-1 may impose limitations on the performance of optical pulse reflection tests. If an optical splitter is used, performing optical reflection tests from the upstream optical connector 127-1 to optical fiber lines 128-1 and 128-2 will result in the reflected light from optical fiber line 128-2 and the reflected light from optical fiber line 129 on the drop side being superimposed, making it difficult to determine if there is a line fault. Therefore, in cases of long drop-type branching as shown in this diagram, it is effective to use a wavelength splitter for the optical connection at the drop point and to perform optical pulse reflection tests at a wavelength different from the power supply light.
[0079] In Figure 9, a new optical fiber cable 130-4 is installed from the optical connection box 124-4 to which the terminal node device 110-3 is connected, to the nearby optical termination box 122-2, so that optical fiber line testing can be performed along the entire length of the optical fiber line 129 used by the optical power supply system. The unused optical fiber line 235 inside this cable and the optical fiber line 129 are optically connected in the wavelength range λp by an optical splitter 200-3 located inside the node device 110-3.
[0080] The power supply light, which has been rerouted through extension optical fiber cable 130-1, is drawn into node devices 110-1, 110-2, and 110-3 via optical connection boxes 124-2, 124-3, and 124-4, which are connection points for node devices, through optical fiber cables 231-1, 231-2, and 231-3 for node device connection. There, a portion is separated at optical branch circuits 200-1, 200-2, and 200-3 to power receiving units 111-1, 111-2, and 111-3 for use as power for the operation of the node devices, while the other portion returns to optical connection boxes 124-2, 124-3, and 124-4 via optical fiber cables 231-1, 231-2, and 231-3 for node device connection, and is transmitted again to downstream optical fiber cables 130-2, 130-3, and 130-4.
[0081] As mentioned above, the optical fiber cable 130-4 is for testing the optical fiber line 129 used by the power supply system. The internal unused optical fiber line 235 is normally unused, and an optical termination box 122-2 to which it is connected has an optical termination unit 210 to prevent leakage of power supply light 204-5 from the optical connector 127-3. To check the integrity of the optical fiber line 129, the optical power supply device 100 should be stopped and disconnected from the optical connector 127-1, and a line test using the power supply light wavelength range λp should be performed between the optical connectors 127-1 and 127-3. This makes it possible to measure the loss of the entire optical fiber line 129 (including the added unused optical fiber line 235) used by the optical power supply system and to perform optical reflection tests from both sides.
[0082] Although Figure 9 shows a configuration in which the optical wavelength splitter 220-1 is placed inside the optical junction box, placing components specific to a particular optical power supply system in highly general-purpose and shared locations such as optical junction boxes and optical termination boxes is not necessarily desirable in terms of maintainability, clarification of management responsibilities, safety, reliability, and environmental resistance. From this perspective, it is desirable to install optical connection devices such as optical splitters and optical wavelength splitters, as well as optical star couplers, which were newly introduced in this embodiment, in the same location or inside the optical power supply device or node device.
[0083] Figure 10 is a configuration diagram of a node device in a fifth embodiment of the present invention, and from the above viewpoint, it is a configuration in which the function of the optical wavelength splitter 220-1 is incorporated inside the node device 110-1 shown in the configuration diagram of Figure 9. The input optical connector 232 is a connector used for connecting the optical fiber line from the upstream power supply device, and the power supply light and test light are used as input light. Inside, there is an optical wavelength splitter 220-1 for separating the line test wavelength range λc and an optical splitter 200-1 for splitting the power supply light to the downstream node device. The line test optical connector 233 can be used for the unused optical fiber on the downstream side that is generated when the optical fiber line is cut (128-2 in Figure 9), and the downstream optical power supply optical connector 234 can be used for connecting to the drop optical fiber line going to the node device further downstream.
[0084] Furthermore, if this node device is to be used as node device 110-1 in Figure 9, this can be achieved by simply moving the optical wavelength splitter in Figure 9 to node device 110-1. In this case, it is necessary to add an optical fiber line in the intermediate optical fiber cables 130-1 and 231-1 that returns from the optical connector 233 for line testing of the node device in Figure 10 to the unused optical fiber line 182-2 in Figure 9. Using a similar approach, it is also possible to incorporate the optical wavelength splitter 220-1 inside the power supply device 100 in Figure 9. [Examples]
[0085] Figure 11 is a configuration diagram showing a sixth embodiment of the present invention, which is an example of a continuous monitoring system that enables continuous monitoring or measurement of the status of the optical fiber line and aggregates the results in a central monitoring device 240. In this figure, one node device 110 is connected to the optical power supply device 100, and the node device 110 is connected from an optical connection box 124 located between optical cables 128-1 and 128-2 via an optical fiber cable 231 for node device connection.
[0086] In this configuration, in order to enable continuous optical line testing even while the optical power supply system is operating, line testing is performed using a wavelength range λc different from the wavelength range λp used by the optical power supply system. An optical wavelength demultiplexer 220-1 located inside the optical power supply device 100 and an optical wavelength demultiplexer 220-2 located inside the node device 110 separate the wavelength ranges λp / λc of the optical signal for line testing and the optical signal for the optical power supply device, thereby preventing interference between the optical signals input and output from the optical power supply system and the line testing device.
[0087] In this diagram, the optical power supply device 100 installed in station building 120-1 has the aforementioned optical wavelength demultiplexer 220-1 built in, and the housing of the optical power supply device 100 is provided with a line test optical connector 233-1. A monitoring optical signal in the wavelength range λc transmitted from the transmitting line test device 241 is input to this connector, combined with the power supply light in the wavelength range λp transmitted by the optical power supply device 100, and then output from the optical connector 127-1, leading to the optical fiber line 128-1 via the optical termination box 122-1.
[0088] Furthermore, inside the optical connection box 124, the upstream optical fiber line 128-1, which is the power supply section, and the downstream optical fiber line 128-2, which is the unused section, are extended to the installation location of the node device 110 by a two-core optical fiber cable 231 for node device connection, and are connected to the node device 110 via optical connector 127-3 and optical connector 233-2 for monitoring and testing. Connecting node devices with optical connectors in this way makes it easier to install and replace equipment and improves maintainability. However, since node devices in optical power supply systems are generally installed in underground facilities or inside conduits, where power supply and access are difficult, these connectors are not necessarily suitable for use in routine optical line testing.
[0089] The node device 110 has a built-in optical wavelength splitter 220-2 which guides the λp optical signal in the wavelength range including the power supply light from the optical fiber line 128-1 to the light receiving unit 111, and sends the monitoring signal component in the wavelength range λc from the monitoring test optical connector 233-2 to the unused section of the optical fiber line 128-2.
[0090] The central office building 120-2 houses an optical connection box 122-2 that accommodates the endpoint of the optical fiber line 128-2, and the receiving-side line test device 242 is connected to the optical fiber line 128-2 via an optical connector 127-2.
[0091] The line test device in Figure 11 transmits a monitoring light of constant intensity in the wavelength range λc from the transmitting line test device 241, and simultaneously measures the received intensity of the monitoring light in the wavelength range λc at the receiving line test device 242. This measures and monitors the loss of the optical fiber line between them, and issues line information and alarms for abnormal loss as line information 243-1 and 243-2. The monitoring light path in this configuration not only passes through optical fiber lines 128-1 and 128-2, but also encompasses the entire power supply light path from the optical power supply device to the node device. Therefore, it becomes possible to simultaneously monitor the health of the optical fiber line 128 and the power supply path of the optical power supply system.
[0092] Furthermore, the line information 243 obtained above is aggregated in the central monitoring device 240 along with equipment information 244 consisting of error and failure information of the optical power supply system transmitted from the optical power supply device 100. This makes it possible to monitor the status of failures and malfunctions of the optical fiber network and the installed optical power supply system in real time, contributing to improved availability and reliability of both the optical fiber network and the optical power supply system, as well as faster fault recovery.
[0093] The configuration and operation of the circuit testing device in this invention are not limited to those described above. For example, the intensity of monitoring light transmitted from the receiving circuit testing device 242 can be measured by the transmitting circuit testing device 241, or transmissions can be performed alternately from both sides and intensity measurements can be taken. It is also possible to perform optical pulse testing from one or both of these monitoring devices. Various measurement frequencies are possible, such as continuously, at regular intervals, or whenever requested by the central monitoring device.
[0094] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.
[0095] Furthermore, each of the above-mentioned configurations, functions, and processing units may be implemented in hardware, either partially or entirely, by designing them as integrated circuits, for example. Alternatively, each of the above-mentioned configurations and functions may be implemented in software by having the processor interpret and execute programs that implement each function. Information such as programs, tables, and files that implement each function can be stored in memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card or SD card.
[0096] Furthermore, the control lines and information lines shown are those deemed necessary for explanatory purposes, and not all control lines and information lines are necessarily shown in the actual product. In practice, it is reasonable to assume that almost all components are interconnected. [Industrial applicability]
[0097] The present invention can be applied to optical power supply systems that use optical fiber power supply technology to simultaneously supply power and perform up and down optical communication from a power supply device to multiple remotely located node devices, enabling multi-point monitoring, data collection, and information communication. [Explanation of Symbols]
[0098] 100: Optical power supply device, 101: Power supply light source, 102: Transmitter 103: Receiver, 104: Power supply light, 105: Up / down communication light 106: Fiber optic cable, 107: Optical splitter 110: Node device, 111: Power receiving unit 120: Station building, 121: Relay station, 122: Optical terminal box 123: Fiber optic cable 124: Optical junction box, 125: Cutting point of the optical fiber line 126: Other fiber optic lines 127: Optical connector 128: Fiber optic cable, 129: Fiber optic cable 130: Extension fiber optic cable 133: Splice, 134: Cut section 200: Optical splitter, 201: Optical connection device 202: Optical test signal 204: Power supply light, 205: First branch power supply light, 206: Second branch power supply light 207: Common optical port, 208: First optical port, 209: Second optical port 210: Optical terminator 211: Upstream test device, 212: Downstream test device, 213: Downward direction test light 220: Optical Wavelength Splitter 221: Common optical port, 222: First optical port, 223: Second optical port 230: Optical star coupler, 231: Optical fiber cable for node device connection 232: Input optical connector, 233: Optical connector for line testing 234: Optical connector for downstream optical power supply, 235: Unused optical fiber 240: Central monitoring device, 241: Transmitter-side line test device, 242: Receiver-side line test device 243: Line information, 244: Equipment information
Claims
1. An optical power supply device that emits power supply light, One or more node devices that receive a portion of the aforementioned power supply light and operate using that power, Includes an optical fiber line connecting a first and second geographically separated point, and connecting to an optical power supply device at a third point which is a transit point between the first and second points, Of the section between the third point and the first point, or the section between the third point and the second point, one is a power supply section used for optical power supply, and the other is an unused section. An optical power supply system in which the power supply section and the unused section are optically connected at the third point of the optical fiber line.
2. The optical power supply system according to claim 1, An optical power supply system in which the optical connection between the power supply section and the unused section is used for optical circuit testing between the endpoints of optical fibers in the section of the optical fiber line including the power supply section and the unused section.
3. The optical power supply system according to claim 1, Including an optical splitter, The aforementioned optical splitter is Including a common optical port, a first optical port, and a second optical port, The optical signal input to the common optical port is separated and output to the first optical port and the second optical port at a constant intensity ratio. The signals input to the first optical port and the second optical port are combined and output to the common optical port. An optical power supply system in which the common optical port is connected to the power supply section side of the optical fiber line, the first optical port is connected to the optical power supply system, and the second optical port is connected to the unused section side of the optical fiber line.
4. The optical power supply system according to claim 3, An optical power supply system in which the unused section is downstream in the direction of propagation of the power supply light, and optical termination processing is performed at the downstream endpoint of the unused section.
5. The optical power supply system according to claim 3, An optical power supply system in which the optical signal branching ratio output to the second optical port is between 50% and 1%.
6. The optical power supply system according to claim 1, Including an optical splitter, The aforementioned optical splitter is Including a common optical port, a first optical port, and a second optical port, The optical signal input to the common optical port is separated into an optical signal in a first wavelength range used by the optical power supply device and an optical signal in a second wavelength range different from the first wavelength range, and the optical signal in the first wavelength range is output to the first optical port and the optical signal in the second wavelength range is output to the second optical port. The optical signal in the first wavelength range input to the first optical port and the optical signal in the second wavelength range input to the second optical port are combined and output to the common optical port. An optical power supply system in which the common optical port is connected to the power supply section side of the optical fiber line, the first optical port is connected to the optical power supply system, and the second optical port is connected to the unused section side of the optical fiber line.
7. The optical power supply system according to claim 6, The second wavelength range mentioned above is used for optical power supply systems in optical circuit testing.
8. The optical power supply system according to claim 6, An optical power supply system in which the first wavelength range is longer than 1.4 μm and the second wavelength range is shorter than 1.4 μm, or the first wavelength range is shorter than 1.2 μm and the second wavelength range is longer than 1.2 μm.
9. The optical power supply system according to claim 1, An optical power supply system comprising a ladder-type configuration in which the power supply light is sequentially branched to node devices by an optical splitter, a star-type configuration in which the power supply light is branched by an optical star coupler, or a combination thereof.
10. The optical power supply system according to claim 7, An optical power supply system comprising means for conducting an optical line test while the optical power supply system is in operation and for aggregating the optical line information obtained in the optical line test at a central office.
11. A node device included in the optical power supply system according to claim 1, comprising an optical port used for inputting and outputting optical signals used for optical line testing.
12. An optical power supply device included in the optical power supply system according to claim 1, comprising an optical port used for inputting and outputting optical signals used for optical line testing.