Determination method

Abstract

A determination method performed by a determination device 100 includes: a first step S1 for calculating the maximum number of optical couplers that can be formed in an optical fiber during communication between transmission devices; a second step S2 for acquiring the existing number of optical couplers formed in the optical fiber; and a third step S3 for determining, on the basis of the result of a comparison between the maximum number of optical couplers and the existing number of optical couplers, whether an optical-fiber-side surface-polished optical coupler can be implemented for the optical fiber. In the second step S2, one test light is outputted from an optical pulse test device to the optical fiber, and the number determined from the number of reflected lights reflected by a test light cutoff filter connected to the optical fiber is employed as the existing number of optical couplers.

Description

Judgment method

[0001] The present disclosure relates to a determination method.

[0002] One example of a network using optical fibers is a network in which a transmission device (OLT: Optical Line Terminal) is installed in a communication building and a transmission device (ONU: Optical Network Unit) is installed in a user's home, and the two transmission devices are connected by an optical cable and an optical splitter.

[0003] In Non-Patent Document 1, a single optical fiber extending from a communications building is connected to an eight-branch optical splitter, and the optical fiber is extended from the optical splitter and connected to the ONU in the user's home. In Non-Patent Document 2, a 2x2 optical coupler is used instead of the optical splitter.

[0004] However, in the methods of Non-Patent Documents 1 and 2, the optical fiber must be cut to stop communication when installing an optical splitter or optical coupler. Therefore, in Non-Patent Document 3, a part of the side surface in the longitudinal direction of the optical fiber is polished, and a part of the communication light is branched from the polished surface. Even if the side surface is polished close to the core, the communication light propagating within the core is maintained, so communication can be maintained.

[0005] “2. Sharing a Single Optical Fiber Among Multiple Customers,” NTT Access Network Service Systems Laboratories, [online], [Retrieved August 8, 2023], <URL: https: / / www.rd.ntt / as / times / 033 / 01 / 02.html> “Principles and Characteristics of Optical Fiber Couplers - Branch Couplers,” Kokyo Co., Ltd., [online], [Retrieved August 8, 2023], <URL: https: / / optipedia.info / laser / fiberlaser / coupler / > Takui Uematsu and four others, “Optical Coupling Technique Based on Fiber Side-Polishing Without Service Interruption,” IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 34, NO. 19, October 1, 2022, pp. 1042-1045

[0006] When multiple branches are formed on a single optical fiber, the power of the communication light output from the transmission device is attenuated accordingly, which can result in the power of the communication light reaching the far-end transmission device being insufficient, potentially causing a communication interruption. To prevent such communication interruptions, information about the branches is registered in a database.

[0007] However, because the branch information is manually entered by workers, the information in the database may not be accurate, which poses a problem in that it is not possible to accurately determine the number of existing branches in the optical fiber to be branched, and therefore to accurately determine whether an optical coupler can be installed in that optical fiber.

[0008] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a technology that can accurately determine whether or not an optical coupler can be installed.

[0009] A determination method according to one aspect of the present disclosure is a determination method performed by a determination device, and includes a first step of calculating the maximum number of optical couplers that can be formed on an optical fiber communicating between transmission devices, a second step of acquiring the existing number of optical couplers formed on the optical fiber, and a third step of determining whether or not an optical fiber side-polished optical coupler can be installed on the optical fiber based on a comparison result between the maximum number of optical couplers and the existing number of optical couplers. In the second step, one test light is output from an optical pulse testing device to the optical fiber, and the number determined from the number of light reflected by a test light blocking filter connected to the optical fiber is set to the existing number of optical couplers.

[0010] A determination method according to one aspect of the present disclosure is a determination method performed by a determination device, which includes a first step of calculating the maximum number of optical couplers that can be formed on an optical fiber communicating between transmission devices, a second step of obtaining the existing number of optical couplers formed on the optical fiber, and a third step of determining whether an optical fiber side polishing type optical coupler can be installed on the optical fiber based on a comparison result between the maximum number of optical couplers and the existing number of optical couplers, and in the second step, the number determined from the number of identification information pieces of the destination transmission devices set in the transmission device is set as the existing number of optical couplers.

[0011] A determination method according to one aspect of the present disclosure is a determination method performed by a determination device, which includes a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices, a second step of acquiring the existing number of optical couplers formed in the optical fiber, and a third step of determining whether or not an optical fiber side-polished optical coupler can be installed in the optical fiber based on a comparison result between the maximum number of optical couplers and the existing number of optical couplers. In the second step, a light capture device receives leakage light of communication light that leaks from a bent portion of the optical fiber, and a number determined from the number of identification information of the destination transmission device obtained from an analysis result of the leakage light is set to the existing number of optical couplers.

[0012] A determination method according to one aspect of the present disclosure is a determination method performed by a determination device, the method comprising: a first step of calculating the maximum number of optical couplers that can be formed on an optical fiber communicating between transmission devices; a second step of acquiring the existing number of optical couplers formed on the optical fiber; and a third step of determining whether or not an optical fiber side-polished optical coupler can be installed on the optical fiber based on a comparison result between the maximum number of optical couplers and the existing number of optical couplers. In the second step, one test light is output in the upstream and downstream directions from an optical pulse testing device to a bent portion of the optical fiber, and the number determined from the number of reflected lights reflected by a test light blocking filter connected to the optical fiber is set to the existing number of optical couplers.

[0013] According to the present disclosure, it is possible to provide a technology that can accurately determine whether or not an optical coupler can be installed.

[0014] FIG. 1A is a diagram showing a first procedure for forming an optical fiber side-polished optical coupler. FIG. 1B is a diagram showing a second procedure for forming an optical fiber side-polished optical coupler. FIG. 1C is a diagram showing a third procedure for forming an optical fiber side-polished optical coupler. FIG. 1D is a diagram showing a fourth procedure for forming an optical fiber side-polished optical coupler. FIG. 2 is a diagram showing an image of attenuation of communication light accompanying the formation of an optical coupler. FIG. 3 is a diagram showing an example of an apparatus configuration used in a first calculation method for the existing number of optical couplers. FIG. 4 is a diagram showing the simple apparatus of FIG. 3. FIG. 5 is a diagram showing measurement results of the reflection amount for a test optical pulse. FIG. 6 is a diagram showing an example of an apparatus configuration used in a second calculation method for the existing number of optical couplers. FIG. 7 is a diagram showing an example of an apparatus configuration used in a third calculation method for the existing number of optical couplers. FIG. 8 is a diagram showing an example of an apparatus configuration used in a fourth calculation method for the existing number of optical couplers. FIG. 9 is a diagram showing a functional block configuration of a determination apparatus. FIG. 10 is a diagram showing a flow for determining whether an optical coupler can be installed. FIG. 11 is a diagram showing the hardware configuration of the determination apparatus.

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0016] The present disclosure relates to an optical multiplexing / demultiplexing technology for demultiplexing light from an optical fiber in communication between transmission devices and multiplexing light into an optical fiber in communication between transmission devices. In particular, the present disclosure relates to a technology for determining whether an optical coupler (an optical fiber side polishing type optical coupler) can be installed on an optical fiber in communication between transmission devices without cutting the optical fiber in communication.

[0017] The present disclosure features a function for determining whether an optical coupler can be installed in optical multiplexing / demultiplexing technology that uses a side polishing method for optical fibers. Therefore, it can be applied to optical waveguides such as glass optical fibers and plastic optical fibers that are commonly used in long-distance communications.

[0018] A method for forming an optical fiber side-polished optical coupler will now be described.

[0019] There is a demand for a technology that can form optical couplers near users without interrupting ongoing communications between transmission devices. Such a technology is the optical fiber side polishing method described in Non-Patent Document 3. This method assumes that communication optical signals are flowing in the core of the optical fiber.

[0020] A portion of the longitudinal side of an optical fiber in communication is ground down to the vicinity of the core. Even when ground down to the vicinity of the core, communication light propagating within the core is maintained, so communication is maintained. Another optical fiber that has been ground down to the vicinity of the core is prepared, and the polished surfaces of the two optical fibers are surface-bonded together, and their positions are adjusted so that the cores are close to each other. As a result, part of the communication light can be moved to the adjacent core.

[0021] By forming such an optical fiber side-polished optical coupler, it is possible to provide users with the required services without interrupting communications. In addition, unlike optical splitters, which are restricted by their insertion position into the optical fiber, this type of coupler is not subject to such restrictions.

[0022] 1A to 1D are diagrams showing steps 1 to 4 for forming an optical fiber side-polished optical coupler.

[0023] 1A, communication is performed by connecting transmission devices 4-1 and 4-2 to both ends of an optical fiber 1. A portion of the optical fiber 1 in the longitudinal direction is bent, and communication light (leakage light) leaking from the bent portion M1 is observed by a monitor device 10.

[0024] Step 2: As shown in Figure 1B, another longitudinal portion of the optical fiber 1 is bent to polish the optical fiber 1. The side surface of this bent portion M2 is polished to the vicinity of the core. When polishing progresses to the vicinity of the core, some of the communication light leaks from the polished surface of the bent portion M2. At this time, light leaks from the polished surface of the bent portion M2 before it leaks from the polished surface of the bent portion M1, so the intensity of the leaked light from the bent portion M1 observed by the monitor device 10 decreases.

[0025] Since the measurement value of the monitor device 10 changes with the polishing time of the bent portion M2, the polishing state of the bent portion M2 can be indirectly determined by observing the intensity of the leaked light at the bent portion M1. When the measurement value of the monitor device 10 reaches a predetermined value, the polishing of the bent portion M2 is completed. Also, the bent portion M1 is returned to its original state.

[0026] Step 3: As shown in Figure 1C, an optical multiplexing / demultiplexing optical waveguide 2 is prepared in advance, with the coating and cladding polished to a distance of several microns from the core. Then, the polished surface D1 of the bent portion M2 of the optical fiber 1 and the polished surface D2 of the bent portion M3 of the optical multiplexing / demultiplexing optical waveguide 2 are surface-bonded to each other, and one or both polished surfaces are slid to move the core relative to one another, and the core is fixed at a position where the desired branching ratio is obtained. This completes the optical coupler 3 with side-polished optical fiber.

[0027] Step 4: As shown in Figure 1D, a transmission device 4-3 is connected to the far end of the optical multiplexing / demultiplexing optical waveguide 2. The transmission device 4-1 communicates with the transmission devices 4-2 and 4-3, respectively, and provides predetermined services to each user. The power of one communication light output from the transmission device 4-1 is branched into two by the optical coupler 3. The power of the two communication lights output from the transmission devices 4-2 and 4-3 is combined into one by the optical coupler 3.

[0028] As described above, by performing steps 1 to 4 in an optical fiber in communication, for example, where time-division multiplexed communication or time-division multiple access communication is being carried out, an optical coupler can be installed without causing a communication interruption.

[0029] FIG. 2 is a diagram showing an image of attenuation of communication light due to the formation of an optical coupler.

[0030] It is efficient if one optical fiber can accommodate many users. However, the power of the communication light attenuates with each addition of an optical coupler (for example, the optical fiber insertion type optical coupler described in Non-Patent Document 2, or the optical fiber side polishing type optical coupler 3 described in Non-Patent Document 3), and the power of the communication light from the transmission device 4-1 to the far-end transmission device 4-2 may become insufficient, possibly causing a communication interruption.

[0031] If the length of the optical fiber in communication is about 10 m, the number of existing optical couplers can be calculated visually. However, it is quite conceivable that the length of the optical fiber in communication will be 100 m or more, making it difficult to calculate the number of existing optical couplers visually.

[0032] Optical coupler installation records are generally stored in a database, but because they are manually entered by workers, incorrect information can be entered. We are planning to install a new optical coupler at a user's home and transmit the data, but we would like to confirm whether it is safe to install the optical coupler. We must avoid a situation where forming a new optical coupler will prevent communication light from reaching the far-end transmission device, causing communication to stop.

[0033] Therefore, in this embodiment, we will explain how to calculate the maximum number of optical couplers that can be formed on one optical fiber currently communicating between transmission devices, and how to calculate the number of optical couplers already formed on that optical fiber.We will also explain how to determine whether or not optical fiber side-polished optical couplers can be installed based on these calculation results.This allows workers to safely determine whether or not new optical couplers can be installed.

[0034] First, we will explain how to calculate the existing number of optical couplers 3. Note that the optical couplers to be calculated are not limited to the optical fiber side-polished type optical coupler 3 described in Non-Patent Document 3, but may be any existing optical coupler such as the optical fiber insertion type optical coupler described in Non-Patent Document 2.

[0035] FIG. 3 is a diagram showing an example of the configuration of a device used in the method 1 for calculating the existing number of optical couplers.

[0036] The optical fiber 1 is connected to a network installed between transmission devices of a PON (Passive Optical Network) system. The PON system is a communication system that uses time division multiplexing or time division multiple access.

[0037] A transmission device 4-1, a test optical coupler 5, and a test optical time domain reflectometer 6 are installed in a communications building. The test optical coupler 5 is a test port pre-attached to the optical fiber 1. The test optical time domain reflectometer 6 is connected to the test optical coupler 5.

[0038] Two users receive service using communication light from transmission device 4-1. Two optical couplers 3-1 and 3-2 are formed using optical multiplexing / demultiplexing optical waveguides 2-1 and 2-2, respectively. Transmission devices 4-2 and 4-3 are connected to the optical couplers 3-1 and 3-2, respectively. Test light blocking filters 7 are installed immediately before the transmission devices 4-2 and 4-3, respectively.

[0039] The optical couplers 3-1 and 3-2 each have four ports f1, f2, g1, and g2. An optical fiber 1 is connected to ports f1 and f2. An optical multiplexing / demultiplexing optical waveguide 2 is connected to ports g1 and g2. Transmission devices 4-2 and 4-3 are connected to port g2 of the optical couplers 3-1 and 3-2, respectively.

[0040] In calculation method 1, the number of existing optical couplers is calculated (determined) using a test optical time domain reflectometer 6.

[0041] Each optical coupler 3 (3-1, 3-2) is provided with one transmission device 4 (4-2, 4-3) and one test light blocking filter 7. Figure 4 shows this simple configuration. One transmission device 4-1 is connected to one transmission device 4-2 via one optical coupler 3-1. In the configuration shown in Figure 4, a test optical pulse tester 6 outputs one test optical pulse with a wavelength of 1650 nm to the optical fiber 1.

[0042] 5 shows the measurement results of the reflection amount for a test optical pulse. For one test optical pulse output from the test optical pulse tester 6, there is one peak at around 0.6 km. This peak is a peak reflected by the test light blocking filter 7 installed immediately before the transmission device 4-2. This peak indicates the presence of the test light blocking filter 7.

[0043] When this test is performed on the transmission devices 4-2 and 4-3 shown in Figure 3, two reflected light peaks occur for one test optical pulse. In Figure 5, the horizontal axis represents the distance from the test optical time domain reflectometer 6, and the two peaks do not overlap. Because the number of test light blocking filters 7 and the number of optical couplers 3 are the same, the number of existing optical couplers 3 can be determined by calculating the number of reflected light peaks using the test optical time domain reflectometer 6.

[0044] Therefore, the test optical time domain reflectometer 6 calculates the number of peaks of reflected light for one test optical pulse output to the optical fiber 1 as the existing number of optical couplers 3. The user may also calculate the existing number of optical couplers 3 from the measurement result of reflected light displayed on the test optical time domain reflectometer 6.

[0045] If a transmission device is connected to the far end of the optical fiber 1 and a test light blocking filter is also installed immediately before the transmission device at the far end, the value obtained by subtracting 1 from the calculated number of existing optical couplers 3 may be used as the existing number of optical couplers 3. Additionally, if there is reflected light from a test light blocking filter installed immediately before the transmission device 4-1, that amount may be subtracted.

[0046] The test optical pulse tester 6 may be, for example, an optical time domain reflectometer (OTDR), an optical frequency domain reflectometer (OFDR), an optical low coherence reflectometer (OLCR), a coherent detection OTDR (C-OTDR), or a frequency-division-multiplexed coherent OTDR (FDM-OTDR).

[0047] The test light blocking filter 7 is, for example, an FBG (Fiber Bragg Grating), a dielectric multilayer filter, or the like.

[0048] FIG. 6 is a diagram showing an example of the configuration of a device used in the method 2 for calculating the existing number of optical couplers.

[0049] In calculation method 2, the computer device 8 is used to calculate (determine) the existing number of optical couplers.

[0050] In FIG. 6, the test optical coupler 5 and test optical pulse tester 6 are omitted from FIG. 3, and a computer device 8 such as a personal computer is connected to the transmission device 4-1.

[0051] The transmission device 4-1 communicates with each of the transmission devices 4-2 and 4-3, but communication cannot be established unless the transmission devices 4-2 and 4-3 are recognized separately. To recognize each transmission device separately, the transmission device 4-1 is configured with an IP (Internet Protocol) address, a MAC (Media Access Control) address, a VLAN-ID (Virtual Local Area Network identification), and the like for each destination transmission device. These values ​​are different for each destination transmission device, so by using these values, the transmission devices can be recognized separately.

[0052] For example, the computer device 8 acquires all IP addresses of the transmission devices 4-2 and 4-3 that are preset as destinations from the transmission device 4-1, and calculates the number of acquired IP addresses. This makes it possible to determine the number of destination transmission devices. Because the number of destination transmission devices and the number of optical couplers are the same, the number of existing optical couplers 3 can be determined by calculating the number of IP addresses.

[0053] Therefore, the computer device 8 acquires the IP addresses of the destination transmission devices from the transmission device 4-1, and calculates the number of IP addresses as the existing number of optical couplers 3. The user may calculate the existing number of optical couplers 3 from the acquired IP addresses. If a transmission device is connected to the far end of the optical fiber 1, the value obtained by subtracting 1 from the calculated existing number of optical couplers 3 may be used as the existing number of optical couplers 3.

[0054] FIG. 7 is a diagram showing an example of a device configuration used in the method 3 for calculating the existing number of optical couplers.

[0055] In the configuration example 3, the optical capture device 9 is used to calculate (determine) the number of existing optical couplers.

[0056] A portion of the optical fiber 1 in the longitudinal direction is intentionally bent, and an optical capture device 9 is placed near the bent portion M4. The optical capture device 9 receives communication light (leakage light) leaking from the bent portion M4. The received light is communication light output from a transmission device 4-1 installed in a communication building.

[0057] This communication light contains information such as IP addresses, MAC addresses, and VLAN-IDs. The values ​​assigned to these vary for each transmission device, so in the case of Figure 7, it can be seen that two transmission devices 4-2 and 4-3 are connected. Since the number of transmission devices and the number of optical couplers are the same, the existing number of optical couplers can be determined by calculating the number of IP addresses, etc.

[0058] Therefore, the optical capture device 9 receives the leaked light from the bend M4 and calculates the number of IP addresses, etc. contained in the leaked light as the existing number of optical couplers 3. The user may calculate the existing number of optical couplers 3 from the displayed results of the IP addresses, etc. If a transmission device is connected to the far end of the optical fiber 1, the existing number of optical couplers 3 may be calculated by subtracting 1 from the calculated existing number of optical couplers 3.

[0059] FIG. 8 is a diagram showing an example of a device configuration used in the method 4 for calculating the existing number of optical couplers.

[0060] In Configuration Example 4, the number of existing optical couplers is calculated (determined) using test optical time domain reflectometers 6-1 and 6-2. In Configuration Example 1, the number of existing optical couplers is calculated using a test optical time domain reflectometer inside the telecommunications building, but in Configuration Example 4, the number of existing optical couplers is calculated using a test optical time domain reflectometer outside the telecommunications building (outdoors).

[0061] Outdoors, a portion of the optical fiber 1 is intentionally bent in the longitudinal direction, and two test optical time domain reflectometers 6-1 and 6-2 are placed near the bent portion M5. Test optical pulses are input from signal output terminals 11 and 12 of the test optical time domain reflectometers 6-1 and 6-2 to the bent portion M5.

[0062] The test optical pulse output from the signal output unit 11 of the test optical pulse tester 6-1 is coupled at the bend M5, enters the optical fiber 1, travels to the right (downstream) in Figure 8, and is reflected by the test light blocking filter 7 located just before the transmission device 4-3. The image of the measurement result is as shown in Figure 5. The presence of one peak indicates the presence of one optical coupler.

[0063] The test optical pulse output from the signal output unit 12 of the test optical time domain reflectometer 6-2 is coupled at the bend M5, enters the optical fiber 1, travels leftward (upward) in Figure 8, and generates Fresnel reflection at the connector of port g1 of the optical coupler 3-1. Because the Fresnel reflection occurring between the optical fiber end face and the air inside the connector is large, the test optical time domain reflectometer 6-2 can measure this Fresnel reflection. As a result, one peak is generated, indicating the presence of one optical coupler. Note that instead of measuring Fresnel reflection, a test light blocking filter 7 may be installed at port g1 of the optical coupler 3-1 and the light reflected by the test light blocking filter 7 may be measured.

[0064] In other words, it can be seen that the optical fiber 1 has a total of two optical couplers.

[0065] Therefore, the user calculates the number of existing optical couplers 3 from the measurement results of the reflection amount and number of reflections displayed on the test optical time domain reflectometers 6-1 and 6-2. If a transmission device is connected to the far end of the optical fiber 1 and a test light blocking filter is also installed immediately before the transmission device, the calculated number of existing optical couplers 3 minus 1 may be used as the number of existing optical couplers 3. Alternatively, if there is reflected light from a test light blocking filter installed immediately before the transmission device 4-1, that amount may be subtracted.

[0066] Next, a method for calculating the maximum number of optical couplers that can be formed on one optical fiber during communication between transmission devices will be described.

[0067] There are two types of branching ratios of branching sections (optical fibers): fixed and variable.

[0068] First, a case where the branching ratio is fixed will be described. Fixed means that the branching ratio of the branching portion formed in the optical fiber is a fixed value (for example, a branching ratio of 50%).

[0069] A case where light is input from port f1 of the optical coupler will be described with reference to FIG.

[0070] First, the relationship between the propagation loss for each path of the optical coupler will be described.

[0071] The propagation loss of the optical coupler is determined for each path. The optical propagation loss from port f1 to port f2 of the optical coupler 3 is defined as the branch loss Lf on the working side, the optical propagation loss from port f1 to port g2 is defined as the branch loss Lg on the branching side, and the excess loss is defined as Lex. The branch loss Lf on the working side is expressed by the following equation (1).

[0072]

[0073] The units of the working side branch loss Lf, the branch side branch loss Lg, and the excess loss Lex are dB. The excess loss is the ratio of the optical power input to port f1 of the optical coupler 3 to the total amount of optical power output to ports f2 and g2. In other words, it is an index showing the optical power that is not output to either port of the optical coupler 3. If any two values ​​of the working side branch loss Lf, the branch side branch loss Lg, and the excess loss Lex are known from equation (1), the value of the remaining one can be determined.

[0074] Next, loss design for establishing communication will be described.

[0075] If the maximum value of the link budget between transmission devices is the maximum link budget Link, the maximum value of the propagation loss of the optical fiber between the transmission devices is the maximum line loss L, and the number of optical couplers is N (N is a positive integer), then in order to establish communication between the transmission devices, equation (2) must be satisfied.

[0076]

[0077] From equation (1), the branch loss Lg on the branch side in equation (2) can be replaced with the branch loss Lf on the working side. Furthermore, if the excess loss Lex is measured in advance and the maximum line loss L and the maximum link budget Link are determined at the network design stage, the unknown quantities in equation (2) are the number N of optical couplers and the branch loss Lf on the working side. Therefore, the range of the branch loss Lf on the working side that satisfies equation (2) can be determined from the number of optical couplers.

[0078] Considering the physical meaning of the working side branch loss Lf, the loss must be equal to or greater than 0. Therefore, the maximum value of the number N of optical couplers whose working side branch loss Lf is in the range of 0 or greater and satisfies formula (2) is the maximum number of optical couplers that can be installed.

[0079] Therefore, if the number of optical couplers installed in the optical fiber 1 to be subjected to optical coupler installation is less than the maximum number, no communication interruption will occur even if a new optical coupler 3 is installed in the optical fiber 1. Here, based on equation (1), the branching loss Lg in equation (2) is replaced with the working side branching loss Lf, but based on equation (1), the working side branching loss Lf in equation (2) may also be replaced with the branching loss Lg.

[0080] Next, the case where the branching rate is variable will be described.

[0081] A case where light is input from port f1 of the n-th optical coupler will be described.

[0082] First, the relationship between the propagation loss for each path of the n-th optical coupler will be described.

[0083] If the propagation loss of the nth optical coupler is taken for each path, the optical propagation loss from port f1 to port f2 of the nth optical coupler is taken as the working side branch loss Lfn, the optical propagation loss from port f1 to port g2 is taken as the branching side branch loss Lgn, and the excess loss is taken as Lex, then the working side branch loss Lfn can be expressed by equation (3), similar to equation (1).

[0084]

[0085] Here, the excess loss Lex is assumed to be constant for each optical coupler. The branch loss Lfn on the working side and the branch loss Lgn on the branching side can take different values ​​depending on the optical coupler number. Even when the branching ratio of the optical coupler is variable, it is necessary to satisfy Equation (4) in order to establish communication, as with Equation (2).

[0086]

[0087] Link is the maximum link budget between the transmission devices. L is the maximum line loss between the transmission devices.

[0088] As with the case where the branching ratio is fixed, the working side branch loss Lfn or branch side branch loss Lgn that satisfies equation (4) has a range. Since the transmission loss increases the farther an optical coupler is from the transmission equipment in the communication building, the range that the working side branch loss Lfn or branch side branch loss Lgn can take varies depending on the optical coupler's number. Since the working side branch loss Lfn or branch side branch loss Lgn is a loss, it will be a value greater than or equal to 0. Therefore, the maximum number of optical couplers for which the working side branch loss Lfn or branch side branch loss Lgn is a value greater than or equal to 0 is the number of optical couplers that can be installed.

[0089] Furthermore, if it is difficult to comprehensively calculate equation (4), it is also possible to calculate the branch loss Lfn on the working side or the branch loss Lgn on the branching side that satisfies equation (4) when the number of optical couplers is maximum and the branching ratio of the optical couplers is set so that the transmission loss between each transmission device is equivalent to the maximum link budget.

[0090] However, excluding the transmission device connected to the optical coupler farthest from the transmission device on the station side, the maximum number that can be installed is the largest integer among the numbers of optical fibers for which the working side branch loss Lfn or branch side branch loss Lgn of the farthest optical coupler is 0 or greater.

[0091] FIG. 9 is a diagram showing a functional block configuration of a determination device 100 that determines whether or not an optical coupler can be installed.

[0092] The determination device 100 includes a calculation unit 101 that calculates the maximum number of optical couplers that can be formed on an optical fiber communicating between transmission devices, an acquisition unit 102 that acquires the existing number of optical couplers formed on the optical fiber, and a determination unit 103 that determines whether or not an optical fiber side polishing type optical coupler can be installed on the optical fiber based on the comparison result between the maximum number of optical couplers and the existing number of optical couplers.

[0093] FIG. 10 is a diagram showing a flow of determining whether or not an optical coupler can be installed.

[0094] First, the calculation unit 101 calculates the maximum number A of optical couplers that can be formed in an optical fiber communicating between transmission devices using the above-mentioned calculation method (step S1).

[0095] Next, the acquiring unit 102 acquires the existing number B of optical couplers formed in the optical fiber (step S2). Specifically, the acquiring unit 102 acquires the existing number B of optical couplers calculated by any one of the above-mentioned calculation methods 1 to 4.

[0096] Calculation method 1 is a calculation method in which one test light is output from the optical pulse tester to the above optical fiber, and the number determined from the number of reflected lights reflected by the test light blocking filter connected to the optical fiber is used as the existing number of optical couplers.

[0097] Calculation method 2 is a calculation method in which the number determined from the number of pieces of identification information of destination transmission devices set in the transmission device is set as the existing number of optical couplers.

[0098] Calculation method 3 is a calculation method in which the leakage light of communication light leaking from the bent portion of the optical fiber is received by an optical capture device, and the number determined from the number of identification information pieces of the destination transmission device obtained from the analysis results of the leakage light is used as the existing number of optical couplers.

[0099] Calculation method 4 is a calculation method in which one test light is output in the upstream and downstream directions from the optical pulse testing device to the bent portion of the optical fiber, and the number determined from the number of reflected lights reflected by the test light blocking filters connected to the optical fiber and the connectors of the optical couplers is used as the existing number of optical couplers.

[0100] The acquiring unit 102 may acquire the existing number of optical couplers by directly receiving it from an optical pulse testing device or the like, or may acquire the existing number of optical couplers by accepting it as input by a user.

[0101] Next, the determining unit 103 compares the maximum number A of optical couplers with the existing number B of optical couplers (step S3).

[0102] If the existing number B of optical couplers is smaller than the maximum number A of optical couplers, the determination unit 103 determines that an optical coupler can be installed on the optical fiber, and displays the determination result that installation is possible and the number of installable optical couplers (=maximum number A of optical couplers - existing number B of optical couplers) on the screen (step S4). In this case, the worker installs a new optical fiber side polishing type optical coupler on the optical fiber.

[0103] On the other hand, if the existing number B of optical couplers is equal to or greater than the maximum number A of optical couplers, the judgment unit 103 judges that installation of an optical coupler to the optical fiber is not possible, and displays the judgment result that installation is not possible on the screen (step S5).

[0104] As described above, according to this embodiment, the determination method performed by the determination device 100 includes a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices, a second step of acquiring the existing number of optical couplers formed in the optical fiber, and a third step of determining whether or not an optical fiber side-polished optical coupler can be installed in the optical fiber based on the comparison result between the maximum number of optical couplers and the existing number of optical couplers.In the second step, one test light is output from the optical pulse testing device to the optical fiber, and the number determined from the number of light reflected by the test light blocking filter connected to the optical fiber is set as the existing number of optical couplers, thereby providing a technology that can accurately determine whether or not an optical coupler can be installed.

[0105] Furthermore, according to this embodiment, the determination method performed by the determination device 100 includes a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices, a second step of acquiring the existing number of optical couplers formed in the optical fiber, and a third step of determining whether or not an optical fiber side-polished optical coupler can be installed in the optical fiber based on the comparison result between the maximum number of optical couplers and the existing number of optical couplers.In the second step, the number determined from the number of identification information pieces of the destination transmission devices set in the transmission device is set as the existing number of optical couplers, thereby providing a technology that can accurately determine whether or not an optical coupler can be installed.

[0106] Furthermore, according to this embodiment, the determination method performed by the determination device 100 includes a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices, a second step of acquiring the existing number of optical couplers formed in the optical fiber, and a third step of determining whether or not an optical fiber side-polished optical coupler can be installed in the optical fiber based on the comparison result between the maximum number of optical couplers and the existing number of optical couplers.In the second step, leaked light of communication light that leaks from a bent portion of the optical fiber is received by an optical capture device, and the number determined from the number of identification information of the destination transmission device obtained from the analysis result of the leaked light is set as the existing number of optical couplers, thereby providing a technology that can accurately determine whether or not an optical coupler can be installed.

[0107] Furthermore, according to this embodiment, the determination method performed by the determination device 100 includes a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices, a second step of acquiring the existing number of optical couplers formed in the optical fiber, and a third step of determining whether or not an optical fiber side polishing type optical coupler can be installed in the optical fiber based on the comparison result between the maximum number of optical couplers and the existing number of optical couplers.In the second step, one test light is output in the upstream and downstream directions from the optical pulse testing device to the bent portion of the optical fiber, and the number determined from the number of reflected light beams reflected by the test light blocking filters and optical coupler connectors connected to the optical fiber is set as the existing number of optical couplers, thereby providing a technology that can accurately determine whether or not an optical coupler can be installed.

[0108] Before installing the optical coupler, it is possible to check whether the optical coupler can be installed and the number of optical couplers that can be installed, so that side-polished optical couplers can be formed on the optical fiber with peace of mind. There will be no communication interruptions due to the installation work. This means that high-quality optical coupler installation and services can be provided to users.

[0109] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure.

[0110] The determination device 100 of the present embodiment described above can be realized, for example, by using a general-purpose computer system including a CPU 901, a memory 902, a storage 903, a communication device 904, an input device 905, and an output device 906, as shown in Fig. 11. The memory 902 and the storage 903 are storage devices. In the computer system, the CPU 901 executes a predetermined program loaded onto the memory 902, thereby realizing each function of the determination device 100.

[0111] The determination device 100 may be implemented by one computer, or by multiple computers, or may be a virtual machine implemented on a computer.

[0112] The program for the determination device 100 can be stored in a computer-readable recording medium such as a HDD, an SSD, a USB memory, a CD, or a DVD. The computer-readable recording medium is, for example, a non-transitory recording medium. The program for the determination device 100 can also be distributed via a communication network.

[0113] REFERENCE SIGNS LIST 1 Optical fiber 2, 2-1, 2-2 Optical multiplexing / demultiplexing optical waveguide 3, 3-1, 3-2 Optical coupler 4-1 to 4-5 Transmission device 5 Test optical coupler 6, 6-1, 6-2 Test optical pulse tester 7 Test light blocking filter 8 Computer device 9 Optical capture device 10 Monitor device 11 Signal output unit 12 Signal output unit 100 Determination device 101 Calculation unit 102 Acquisition unit 103 Determination unit 901 CPU 902 Memory 903 Storage 904 Communication device 905 Input device 906 Output device

Claims

1. A determination method performed by a determination device, comprising: a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices; a second step of acquiring the existing number of optical couplers formed in said optical fiber; and a third step of determining whether or not an optical fiber side polishing type optical coupler can be installed in said optical fiber based on a comparison result between said maximum number of optical couplers and said existing number of optical couplers, wherein in said second step, a single test light is output from an optical pulse testing device to said optical fiber, and the number determined from the number of reflected light beams reflected by a test light blocking filter connected to said optical fiber is regarded as the existing number of optical couplers.

2. A determination method performed by a determination device, comprising: a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices; a second step of acquiring the existing number of optical couplers formed in the optical fiber; and a third step of determining whether or not an optical fiber side polishing type optical coupler can be installed in the optical fiber based on a comparison result between the maximum number of optical couplers and the existing number of optical couplers, wherein in the second step, a number determined from the number of identification information of destination transmission devices set in the transmission device is set as the existing number of optical couplers.

3. A determination method performed by a determination device, comprising: a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices; a second step of acquiring the existing number of optical couplers formed in the optical fiber; and a third step of determining whether or not an optical fiber side polishing type optical coupler can be installed in the optical fiber based on a comparison result between the maximum number of optical couplers and the existing number of optical couplers, wherein in the second step, a light capture device receives leakage light of communication light leaking from a bent portion of the optical fiber, and a number determined from the number of identification information of the destination transmission device obtained from the analysis result of the leakage light is set as the existing number of optical couplers.

4. A determination method performed by a determination device, comprising: a first step of calculating the maximum number of optical couplers that can be formed in an optical fiber communicating between transmission devices; a second step of acquiring the existing number of optical couplers formed in said optical fiber; and a third step of determining whether or not an optical fiber side polishing type optical coupler can be installed in said optical fiber based on a comparison result between said maximum number of optical couplers and said existing number of optical couplers, wherein in said second step, a single test light is output from an optical pulse testing device in the upstream and downstream directions to a bent portion of said optical fiber, and the number determined from the number of reflected lights reflected by a test light blocking filter connected to said optical fiber is determined to be the existing number of optical couplers.

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