Optical fiber switching method and optical communication device

Abstract

The purpose of the present disclosure is to reduce communication downtime that occurs in association with optical fiber changeover.　The present disclosure is an optical fiber changeover method for changing over the other party of a first optical communication device connected to a first optical fiber from a second optical communication device connected to the first optical fiber to a third optical communication device connected to a second optical fiber, the method involving polishing the sides of the first and second optical fibers to near the core of each and bring the polished surfaces of the first and second optical fibers into proximity to form an optical coupler coupling the first and second optical fibers, and using the optical coupler to change over from the first optical fiber to the second optical fiber.

Description

[Technical Field]

[0001] The present disclosure relates to a technique for switching optical fiber connections in an optical communication network. [Background technology]

[0002] Optical access networks provide users with internet and telephone services. When replacing equipment that makes up an optical access network, optical fiber switching work is carried out to switch from the original equipment to the new equipment. The optical fiber at the source of the transfer is used for communications, but the optical fiber switching work involves cutting the optical fiber and performing fusion splicing, etc. (see, for example, Non-Patent Document 2), so communications are stopped during the work period. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Tomohiro Konuma, Akito Nishimura, Shoichiro Matsuo, Kuniharu Himeno, "Fundamentals and Latest Technologies of Optical Fiber Connection for Communication", Laser Research, Vol. 40, No. 6, 2012, p. 435 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to reduce communication outage time that occurs due to optical fiber switching. [Means for solving the problem]

[0005] The optical fiber switching method of the present disclosure includes: 1. An optical fiber switching method for switching a communication partner of a first optical communication device connected to a first optical fiber from a second optical communication device connected to the first optical fiber to a third optical communication device connected to the second optical fiber, comprising: polishing the side surfaces of the first optical fiber and the second optical fiber to the vicinity of their cores; an optical coupler that couples the first optical fiber and the second optical fiber by bringing the polished surfaces of the first optical fiber and the second optical fiber close to each other; The optical coupler is used to switch from the second optical communication device to the third optical communication device.

[0006] The present disclosure configures an optical coupler using a first optical fiber and a second optical fiber, and connects a first optical communication device to a third optical communication device using the optical coupler, thereby enabling switching from the second optical communication device to the third optical communication device without disconnecting the first optical fiber, thereby reducing communication downtime that occurs due to optical fiber switching.

[0007] In the present disclosure, the optical coupler may be configured in a state in which the first optical communication device and the second optical communication device maintain communication, and the optical coupling conditions in the optical coupler may be adjusted based on the optical signals transmitted and received by the first optical communication device and the second optical communication device.

[0008] In the present disclosure, after blocking the optical signal transmitted from the second optical communication device, the third optical communication device may transmit an optical signal to the first optical communication device.

[0009] In the present disclosure, the first optical communication device may, while communicating with the second optical communication device and the third optical communication device, compare the power of a first optical signal received from the second optical communication device with the power of a second optical signal received from the third optical communication device, and transmit an instruction to stop transmitting the optical signal when the power of the second optical signal becomes greater than the power of the first optical signal, and the second optical communication device of the second optical communication device and the third optical communication device that has received the instruction may stop transmitting the optical signal. Here, the first optical communication device may communicate with the second optical communication device and the third optical communication device using time division multiplexing communication.

[0010] The optical communication device of the present disclosure is an optical communication device that functions as the first optical communication device, the first optical fiber is connected to a second optical fiber connected to a third optical communication device by an optical coupler; comparing a power of a first optical signal received from the second optical communication device with a power of a second optical signal received from the third optical communication device while performing communication between the second optical communication device and the third optical communication device; When the power of the second optical signal becomes greater than the power of the first optical signal, an instruction to stop transmission of the optical signal is transmitted.

[0011] The above disclosures can be combined as much as possible. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to reduce the communication downtime that occurs due to optical fiber switching. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an example of the structure of an optical fiber. [Figure 2] 1 is an example of a configuration for optical communication. [Figure 3] This is an example of actual optical fiber wiring. [Figure 4] This is an example of services provided by the OLT installed in a new communications building. [Figure 5] 1 is an example of a method for cutting an optical fiber. [Figure 6] This is an example of connecting optical fibers using fusion splicing. [Figure 7] This is an example of optical fiber switching, where (a) shows the state before switching and (b) shows the state after switching. [Figure 8] 1 shows a schematic configuration of a switching point in the present disclosure. [Figure 9] An example of a method for producing an optical coupler according to the present disclosure will be described. [Figure 10] 1 illustrates an example of an optical coupler of the present disclosure. [Figure 11] This shows the change over time in the power of the optical signal from the ONU reaching each OLT. [Figure 12] This is an example of a state in which optical signals output from each OLT during switching overlap. [Figure 13] 10A and 10B show examples of blocking of an optical signal from OLT#1, where (a) shows the case where the optical fiber is bent, and (b) shows the case where the optical fiber is cut. [Figure 14] This is an example of timing control of optical signals output from each OLT in the old and new telecommunications buildings. [Figure 15] This is an example of the change and timing control of the optical signal from ONU#1 by the optical coupler. [Figure 16] This is an example of the power of the optical signal received by ONU#1. [Figure 17] 1 is an example of a configuration for monitoring the power of an optical signal in an ONU. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0015] As shown in FIG. 1 , the optical fiber 95 has a three-layer structure consisting of a core 91, a cladding 92 surrounding the core 91, and a coating 94 for protecting the cladding 92. The core 91 and the cladding 92 can be made of any material, but in this embodiment, they are made of glass. Hereinafter, the portion made of glass, including the core 91 and the cladding 92, will be referred to as the glass portion 93. The core 91 is mainly composed of pure silica glass, with germanium dioxide used as an additive. The addition of germanium dioxide increases the refractive index. On the other hand, the cladding 92 is made only of pure silica glass, so that the cladding 92 has a lower refractive index than the core 91. Because the refractive indexes of the core 91 and the cladding 92 are different, total reflection occurs at the boundary surface, and the optical signal propagates within the core 91.

[0016] As shown in Figure 2, optical communication involves installing devices 80#1 and 80#2 at either end of an optical fiber 95. Optical signals are output from the devices 80, and via the optical fiber 95, the devices 80 recognize each other, enabling optical communication. Using this principle, services such as the Internet and telephone are provided to terminal users.

[0017] An example of actual optical fiber wiring is shown in Figure 3. Figure 3 shows a wiring configuration for providing services. An optical line terminal (OLT) 81 is installed in a telecommunications building, and an optical network unit (ONU) 82 is installed at a user's terminal. The OLT 81 and ONU 82 correspond to devices 80#1 and 80#2, respectively. The optical signals output from the OLT 81 and ONU 82 have different wavelengths. In this disclosure, the wavelength output from ONU 82#1 is defined as wavelength λ1, and the wavelength output from OLT 81#1 is defined as wavelength λ2. In this embodiment, an example is shown in which an integrated distribution module (IDM) 83 is installed in the telecommunications building, and an optical cable 84 in which multiple optical fibers 95 are bundled is used to connect the OLT 81 and ONU 82.

[0018] As time passes after a telecommunications building is constructed, the building itself deteriorates. For example, the concrete may crack, and moisture may seep in through the cracks. The building is equipped with a large number of electrical devices, such as OLT81. If moisture gets in, it can affect the electrical equipment and, in the worst case scenario, cause it to stop working. This means that services cannot be provided to terminal users.

[0019] Therefore, as shown in Figure 4, a new communications building is constructed, a new OLT 81#2 is installed in the communications building, and services are provided using optical signals from the OLT 81#2. To do this, it is necessary to switch the optical cable 84-1 somewhere to a new optical cable 84-2.

[0020] In the current construction method, at switching point PS where optical cable 84-2 of optical cable 84-1 can reach, the optical fiber in old optical cable 84-1 extending from the old telecommunications building is cut, and the cut optical fiber is spliced ​​to the optical fiber of optical cable 84-2 extending from the new telecommunications building. Figure 5 shows the cutting process, and Figure 6 shows the splicing process. The optical fiber contained in optical cable 84-1 is removed, and the optical fiber coating 94-1 is removed to expose the glass portion 93-1. Both ends of the glass portion 93-1 are placed on fixed base 21. As pressing base 22 moves from bottom to top, the glass portion 93-1 of the optical fiber is sandwiched between cutter 23, which is a metal blade, and pressing base 22. By moving the blade of cutter 23 forward, the blade of cutter 23 comes into contact with the glass portion 93-1, scratching it. Due to the pressure applied by the pressure table 22, the scratched glass portion 93-1 cracks, and the optical fiber in the optical cable 84-1 is cut.

[0021] 6 shows an example of a method for connecting optical fibers. Optical fiber 95-1 in optical cable 84-1 and optical fiber 95-2 in optical cable 84-2 are arranged to face each other, and the cores of glass portions 93-1 and 93-2 are aligned with high precision. Thereafter, discharge is generated from electrode rod 24 to melt the end faces of glass portions 93-1 and 93-2, thereby connecting optical fibers 95-1 and 95-2 (see, for example, Non-Patent Document 1).

[0022] In the current construction work, as shown in Figures 5 and 6, the optical fiber 95-1 is cut and the optical fibers 95-1 and 95-2 are reconnected. Because the optical fiber 95-1 is cut, the optical signal propagating through the optical fiber 95-1 also stops. The time required for these construction works, that is, the time communications are stopped, is approximately 5 to 10 minutes. Therefore, in this disclosure, in order to reduce the communication stoppage time, the optical fiber is switched from the old communications building to the new communications building, preferably without stopping communications.

[0023] (Example 1) FIG. 7 shows diagrams before and after switching. The diagram shows an optical signal output from ONU 82#1. In this embodiment, an optical coupler 85 is configured at switching point PS to connect optical fibers 95-1 and 95-2, and the optical coupler 85 is used to switch the optical signal from ONU 82#1 from OLT 81#1 to OLT 81#2. An optical coupler combines and branches optical signals.

[0024] In the present disclosure, ONU 82#1 functions as a first optical communication device, OLT 81#1 functions as a second optical communication device, and OLT 81#2 functions as a third optical communication device. Optical fiber 95-1 functions as a first optical fiber, and optical fiber 95-2 functions as a second optical fiber. Although not shown, an optical signal from OLT 81#1 to ONU 82#1 functions as a first optical signal, and an optical signal from OLT 81#2 to ONU 82#1 functions as a second optical signal.

[0025] Specifically, the optical fiber switching method of the present disclosure is an optical fiber switching method for switching a communication partner of an ONU 82#1 connected to an optical fiber 95-1 from an OLT 81#1 connected to the optical fiber 95-1 to an OLT 81#2 connected to an optical fiber 95-2, The side surfaces of the optical fibers 95-1 and 95-2 are polished to the vicinity of the core 91. The polished surfaces of the optical fibers 95-1 and 95-2 are brought close to each other to form an optical coupler 85 that couples the optical fibers 95-1 and 95-2; An optical coupler 85 is used to switch from OLT 81#1 to OLT 81#2.

[0026] Fig. 8 shows a schematic configuration of a switching point PS in the present disclosure. In the present disclosure, an optical coupler 85 is configured at the switching point PS to couple an optical signal propagating through the core of optical fiber 95-1 to the core of optical fiber 95-2. In this way, in the present disclosure, by configuring the optical coupler 85 at the switching point PS, optical signals are switched as shown in Fig. 7.

[0027] The optical coupler 85 can have any configuration, but for example, the optical coupler 85 is made by polishing the side of an optical fiber 95-1. As shown in Figure 1, the optical fiber 95-1 is composed of a coating 94, a cladding 92, and a core 91 from the outside. The ONU 82#1 and the OLT 81#1 maintain communication without disconnection, and the optical signal propagates inside the core 91 of the optical fiber 95-1. The optical coupler 85 made by polishing the side of the optical fiber 95 is shown in Figure 9.

[0028] Figure 9 shows cross-sectional views of the side surface processing of optical fibers 95-1 and 95-2. Although the coating layer is not shown in the drawing (Figure 9(a)), the coating covering optical fiber 95-1 is polished, and then the cladding 92 is polished (Figure 9(b)), and polishing continues up to the vicinity of the core 91 (Figure 9(c)). Optical fiber 95-2 is also polished in the same manner as optical fiber 95-1 (Figure 9(d)).

[0029] Here, a feature of the present disclosure is that the polishing of the optical fibers 95-1 and 95-2 does not reach the core 91. During polishing, the loss may be evaluated while inputting an optical signal into the optical fiber 95-1. In this case, the loss is maintained at 0.5 dB or less. A feature of the present disclosure is that polishing the optical fiber 95-1 does not interrupt communication.

[0030] Furthermore, in this embodiment, the optical coupling conditions in the optical coupler 85 may be adjusted based on the optical signals transmitted and received by the OLTs 81#1 and 81#2. For example, the power of the optical signal transmitted from the ONU 82#1 is measured in the optical fibers 95-1 and 95-2 branched by the optical coupler 85. This measurement can be performed by bending the optical fibers 95-1 and 95-2 and using the leaked light from the bent portions.

[0031] By adjusting the positions of the polished optical fibers 95-1 and 95-2 relative to each other (FIG. 9(d)) and aligning them (FIG. 9(e)), the optical signal propagating through the core 91 of the optical fiber 95-1 can be transferred to the core 91 of the optical fiber 95-2. By adjusting the positions of the optical fibers 95-1 and 95-2, the coupling conditions of the optical fibers 95-1 and 95-2 can be adjusted.

[0032] Here, the coupling conditions are determined by the longitudinal distance in the state shown in Figure 9(e) and the distance between the two cores 91. Calculations can be made by using the coupling conditions as parameters. A portion of the optical signal is propagated to the fiber 95-2 side as branched light, but by changing the coupling conditions, it is possible to transfer 100% of the power of the optical signal in optical fiber 95-1 to optical fiber 95-2, or to transfer half of the power of the optical signal in optical fiber 95-1 to optical fiber 95-2.

[0033] 10 shows an example of the calculation results for branching in the optical coupler 85. It can be seen that by joining two polished optical fibers and adjusting their positions, a portion of the optical signal propagating through the core of the optical fiber 95-1 is transferred to the core of the optical fiber 95-2. As mentioned above, the amount of power transferred from the optical fiber 95-1 to the optical fiber 95-2 is determined by the coupling conditions.

[0034] (Example 2) Figure 11 shows the change over time as the optical signal from ONU 82 reaches each of OLTs 81#1 and 81#2. The horizontal axis shows the time before, during, and after switching, and the vertical axis shows the power of the optical signal output from ONU 1 reaching each OLT. As shown in Figure 11, as the two fiber cores 91 approach each other, the power shifts.

[0035] In the present disclosure, since there are two OLTs 81, if optical signals are transmitted from both OLT 81#1 and OLT 81#2 during switching, the optical signals from OLT 81#1 and OLT 81#2 will overlap, as shown in Fig. 12. When the two overlapping signals from OLT 81#1 and OLT 81#2 arrive at ONU 82#1, ONU 82#1 will be unable to process the optical signals, and communication between OLT 81#1 and OLT 81#2 and ONU 82#1 will stop.

[0036] Therefore, this embodiment is provided with a configuration that prevents overlapping of communications between OLT 81#1 and OLT 81#2. Before the cores of the two optical fibers 95-1 and 95-2 are brought closer to each other, the optical signal transmitted from OLT 81#1 is blocked. For example, as shown in FIG. 13(a), a bend 95-1B is imparted to the optical fiber 95-1 extending from the OLT 81#1, thereby stopping the communication from OLT 81#1. Alternatively, the optical fiber 95-1 may be cut, as shown in FIG. 13(b).

[0037] Regarding the process procedure and communication status, for example, communication from OLT 81#1 is stopped before alignment is performed by optical coupler 85 arranged at switching point PS. This stops communication from OLT 81#1, making it possible to prevent two optical signals from OLT 81#1 and OLT 81#2 from overlapping and reaching ONU 82#1.

[0038] After that, by bringing the two cores 91 of the optical fibers 95-1 and 95-2 in the optical coupler 85 closer together, the optical signal from the OLT 81#2 side reaches the ONU 82#1 side. An optical signal is also output from the ONU 82#1 and reaches the OLT 81#2. Two-way communication between the OLT 81#2 and the ONU 82#1 begins. Communication with the OLT 81#1 is stopped, and communication is halted until communication with the OLT 81#2 begins.

[0039] (Embodiment Example 3) In the second embodiment, communication of OLT 81#2 is stopped, but in the third embodiment, a method for not stopping communication is shown. FIG. 14 shows a method for not stopping communication. To prevent communication from being stopped, it is sufficient that optical signals do not arrive at ONU 82#1 from both OLT 81#1 and 81#2 at the same time. Therefore, in this embodiment, a new function is added to ONU 82#1. This function is, for example, time division multiplexing communication.

[0040] Optical signals are output from OLT 81#1 and OLT 81#2, and ONU 82#1, OLT 81#1, and OLT 81#2 are provided with a control function to prevent these optical signals from overlapping. By using time division multiplexing communication, the optical signals from each OLT 81#1 and 81#2 do not overlap, as shown in Figure 14. If it is known that optical signals from OLT 81#1 and OLT 81#2 arrive alternately with a predetermined time interval between them, communication interruptions at ONU 82#1 can be prevented.

[0041] The timing control of optical signals from OLT 81#1 and OLT 81#2 will be described with reference to Figure 15. Figure 15(a) shows the state before the optical coupler 85 is built, and shows OLT 81#1 and ONU 82#1 communicating. With the optical coupler 85 built, the optical signal from ONU 82#1 is split and reaches OLT 81#1 and OLT 81#2, as shown in Figure 15(b).

[0042] As shown in Figure 15(c), the timing at which the optical signal from OLT 81#2 is output is after the optical signal from ONU 82#1 arrives. The optical signal from ONU 82#1 can include an optical signal that controls the timing of OLT 81#1 and OLT 81#2. This allows for timing control of the optical signals output from OLTs 81#1 and 81#2 in the old and new communication buildings, as shown in Figure 14.

[0043] 16 shows the magnitude of the power of the OLTs 81#1 and 81#2 received by the ONU 82#1 during switching. The ONU 82#1 is provided with a function for receiving the magnitude of the power arriving from each of the OLTs 81#1 and 81#2.

[0044] Before fabricating the optical coupler 85, only the optical signal was from the OLT 81#1 installed in the old communications building, as shown in Fig. 16(a). When the optical coupler 85 is used, the power of the OLT 81#1 decreases and the power of the OLT 81#2 increases, as shown in Fig. 16(b).

[0045] Furthermore, by adjusting the position of the fiber of the optical coupler 85, the power of OLT 81#1 and OLT 81#2 becomes the same, as shown in Figure 16(c). At this time, ONU 82#1 issues a command to stop the optical signal from OLT 81#1. The command from ONU 82#1 is split into two by the optical coupler 85 provided at the switching point PS, but since only OLT 81#1 follows this command, the power to OLT 81#1 is turned off and no optical signal is output from OLT 81#1. Therefore, as shown in Figure 16(d), the power of OLT 81#1 disappears.

[0046] Furthermore, by optimizing the positions of the cores 91 of the two optical fibers 95-1 and 95-2 of the optical coupler 85, as shown in Fig. 16(e), the optical signal output from the OLT 81#2 can be coupled to the optical fiber 95-1 without any loss in the optical coupler 85. Finally, the OLT 81#1 is removed.

[0047] 17 shows how ONU 82#1 is given the function of receiving the magnitude of the power arriving from each of OLTs 81#1 and 81#2. It shows that ONU 82 is connected to optical fiber 95-1, receives an optical signal from OLT 81, and ONU 82 itself outputs an optical signal.

[0048] FIG. 17 shows the internal structure of the ONU 82. The ONU 82 includes a light source (laser) 31, a photodiode 32, a wavelength separation filter 33, and a signal processing unit 35. When the optical signal output from the OLT 81 arrives inside the ONU 82, it is reflected by the wavelength separation filter 33 and reaches the photodiode 32. This photodiode 32 is a component for receiving the optical signal from the OLT 81. The optical signal output from the ONU 82 is output from the light source (laser) 31 built into the ONU 82. To separate the light reception and light emission, the light source 31 and the photodiode 32 are provided separately. Furthermore, because the wavelengths of the light source 31 and the photodiode 32 are different, a wavelength separation filter 33 is used. Specifically, a wavelength of 1310 nm is applied to the light source 31, and a wavelength of 1490 nm is applied to the photodiode 32. However, these wavelengths can also be changed depending on the system.

[0049] Optical signals from OLT81#1 and OLT81#2 arrive alternately at the photodiode 32. Since the photodiode 32 can convert optical signals into electrical signals, it can also convert the optical signals from OLT81#1 and OLT81#2 into electrical signals. The OLT 81 and ONU 82 are assigned MAC addresses to identify the devices. MAC in the MAC address stands for Media Access Control and is an identifier used for identification. Since no two devices have the same number, the signal processing unit 35 uses this MAC address to identify and manage the devices. Therefore, OLT81#1 and OLT81#2 have different identifiers.

[0050] Even if the photodiode 32 converts the optical signal into an electrical signal, the signal processing unit 35 can still read the MAC address. A signal processing unit 35 capable of distinguishing the MAC address identification of the OLT 81 is provided downstream of the photodiode 32, and distributes the optical signals of OLT 81#1 and OLT 81#2. In other words, the signal processing unit 35 divides the optical signals into OLT 81#1 and OLT 81#2 and also measures the received optical power. Therefore, by moving the optical fiber core of the optical coupler 85, the signal processing unit 35 provided in the ONU 82 can distinguish between OLT 81#1 and 81#2 and can also display the received optical power.

[0051] The signal processing unit 35, while communicating with the OLTs 81#1 and 81#2, compares the power of the first optical signal received from the OLT 81#1 with the power of the second optical signal received from the OLT 81#2. When the power of the second optical signal becomes greater than the power of the first optical signal, the signal processing unit 35 transmits an instruction to stop transmitting the optical signal. Upon receiving this instruction, the OLT 81#1 of the OLTs 81#1 and 81#2 stops transmitting the optical signal.

[0052] As described above, the method shown in the third embodiment allows switching from the old communication building to the new communication building without stopping the communication between the OLTs 81#1 and 81#2. [Explanation of symbols]

[0053] 21:Fixed stand 22: Pressing table 23: Cutter 24: Electrode rod 31:Light source 32: Photodiode 33: Wavelength separation filter 34: Separation part 35: Signal processing section 80: Equipment 81:OLT 82:ONU 83:IDM 84, 84-1, 84-2: Optical cable 85: Optical coupler 91: Core 92: Clad 93, 93-1, 93-2: Glass section 94, 94-1, 94-2: Covering 95, 95-1, 95-2: Optical fiber

Claims

1. 1. An optical fiber switching method for switching a communication partner of a first optical communication device connected to a first optical fiber from a second optical communication device connected to the first optical fiber to a third optical communication device connected to the second optical fiber, comprising: polishing the side surfaces of the first optical fiber and the second optical fiber to the vicinity of their cores; an optical coupler that couples the first optical fiber and the second optical fiber by bringing the polished surfaces of the first optical fiber and the second optical fiber close to each other; using the optical coupler to switch from the second optical communication device to the third optical communication device; Optical fiber switching method.

2. configuring the optical coupler in a state in which the first optical communication device and the second optical communication device maintain communication; adjusting a condition for coupling light in the optical coupler based on the optical signals transmitted and received by the first optical communication device and the second optical communication device; The optical fiber switching method according to claim 1 .

3. and transmitting an optical signal from the third optical communication device to the first optical communication device after blocking the optical signal transmitted from the second optical communication device. The optical fiber switching method according to claim 1 .

4. the first optical communication device compares the power of a first optical signal received from the second optical communication device with the power of a second optical signal received from the third optical communication device while communicating with the second optical communication device and the third optical communication device; transmitting an instruction to stop transmission of the optical signal when the power of the second optical signal becomes greater than the power of the first optical signal; the second optical communication device of the second optical communication device and the third optical communication device that has received the instruction stops transmitting an optical signal; The optical fiber switching method according to claim 1 .

5. the first optical communication device communicates with the second optical communication device and the third optical communication device using time division multiplexing communication; 5. The optical fiber switching method according to claim 4.

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