JP6346839B2 - Detour optical line construction method and detour optical line system - Google Patents

Description

  The present invention relates to a method of constructing a detour optical line provided for temporarily switching an optical line, for example, in a troubled relocation work, etc., and such a detour light beam, with respect to a working optical line using an optical fiber connecting between transmission devices. More particularly, the present invention relates to a bypass optical line construction method and a bypass optical line system in which a propagation delay amount is easily controlled.

  In recent years, service interruption switching technology has been developed that enables the transfer of services from the working optical line to the detour optical line while maintaining the communication service, such as in-service, in trouble relocation work of the optical communication network, etc. (For example, see Non-Patent Document 1 and Non-Patent Document 2).

  In order to achieve such service uninterruptible switching technology, even when switching from the working optical line to the detouring optical line, the working optical line in the detoured section is not affected so that communication before and after switching is not affected. It is necessary to duplicate both routes while matching the propagation delay amount with the detour optical line.

  Therefore, it is necessary to accurately grasp the propagation delay difference between the optical signal propagating through the working optical line and the optical signal propagating through the detour optical line in the detoured section.

  As a means of measuring the propagation delay difference, the propagation delay difference between the working optical line and the detour optical line in the detoured section is measured from the similarity (correlation) of the signal pattern using the ONU upstream signal as the test light. And a fine measurement method for detecting a phase difference of a signal and measuring a propagation delay difference with high accuracy have been proposed (see Non-Patent Document 3).

Manabe et al .: “Basic study of optical fiber uninterruptible switching system using variable electrical delay device”, IEICE Technical Report, OFT2012-46, pp. 23-26, 2012. Inoue et al: “Dynamic Delay Adjustment Characterization using Buffer-type Delay Line for Changing Optical Access Line Routes without Service Interruption”, OECC / ACOFT 2014, TH10C, Melbourne, Australia, July 2014. Inoue et al: “Wide-range, high-accuracy delay difference measurement between duplex transmission lines using pulse correlation analysis and phase detector”, IEICE Technical Report, OFT2013-16, pp. 17-20, 2013.

  Since it is impossible to reduce the propagation delay amount in the existing working optical line from the current state, in order to adjust the propagation delay amount between the working optical line and the detouring optical line in the detoured section to match. Needs to be achieved by increasing the propagation delay of the optical signal passing through the detour optical line.

  For this purpose, it is necessary to provide a propagation delay amount adjusting unit for increasing the propagation delay amount of the optical signal in the middle of the detour optical line.

  However, conventionally, optical fibers having the same specifications are often used for the working optical line and the bypass optical line. In this case, if the lengths of the working optical line and the bypass optical line in the bypassed section are the same, the propagation delay amounts of the active optical line and the bypass optical line in the bypassed section are theoretically the same. Become.

  However, it is not realistic that the lengths of the working optical line and the detour optical line in the detoured section are exactly the same, and even if they are the same, there are also manufacturing errors inherent to the optical fiber. The propagation delay amount between the working optical line and the detour optical line in the detoured section will not be the same.

  Therefore, the necessity of providing a delay adjustment unit for increasing the propagation delay amount of the optical signal still in the middle of the detour optical line is not excluded.

  However, if such a propagation delay amount adjustment unit is provided in the middle of the detour optical line, the propagation delay amount of the detour optical line further increases by adding the inherent propagation delay amount of the propagation delay amount adjustment unit itself. Resulting in.

  Therefore, the propagation delay amount of the detour optical line must be smaller than the propagation delay amount of the working optical line in the detoured section, even if the propagation delay amount inherent in the propagation delay amount adjusting unit is added.

  The present invention has been made paying attention to the above circumstances, and the purpose thereof is to make the propagation speed of the propagating light faster than the propagation speed of the light passing through the working optical line in the detoured section. A bypass optical line is used, and further, the propagation delay amount of the bypass optical line is increased by a propagation delay amount adjusting means provided in the bypass optical line, thereby reducing the propagation delay amount of the bypass optical line in the section to be bypassed. It is an object of the present invention to provide a detour optical line construction method and detour optical line system that can match the propagation delay amount of the detour optical path.

  In order to achieve the above object, a first aspect of the present invention includes the following components.

  The second aspect of the present invention includes the following components.

  That is, the detouring optical line construction method and the detouring optical line system for the working optical line connecting between the transmission apparatuses according to the second aspect of the present invention include a pair of detouring start ends and a detouring end end respectively connected to the working optical line. Propagation delay amount adjusting means for connecting the both ends of the bypass optical line to the optical coupler and adjusting the propagation delay amount of the signal propagating through the bypass optical line is provided in the middle of the bypass optical line. Furthermore, the working optical line and the bypass optical line are optical fibers having the same specifications. Further, the length of the detour optical line from the detour start end to the detour end end is made shorter than the length of the working optical line from the detour start end to the detour end end. As a result, the total propagation delay amount of the signal propagating through the detour optical line from the detour start end to the detour end end by the detour optical line and the propagation delay amount adjusting means is changed from the detour start end to the detour end end. The propagation delay amount of the signal to be propagated is made smaller.

  As an example, among the working optical lines from the detour start end to the detour end end, the working optical line portion longer than the detour optical line from the detour start end to the detour end end is bundled in the vicinity of the detour start end or the detour end end. You may do it.

  And in these 1st and 2nd viewpoints, the signal which propagates a detour optical line from a detour start end to a detour end end is further made by delaying a signal which propagates a detour optical line by propagation delay amount adjustment means, The total propagation delay amount by the detour optical line and the propagation delay amount adjusting means is made to coincide with the propagation delay amount of the signal propagating through the working optical line from the detour start end to the detour end end. This enables uninterrupted switching from the working optical line to the bypass optical line in service.

  That is, according to the present invention, the propagation delay of the propagation light provided in the bypass optical line is such that the propagation speed of the propagating light is higher than the propagation speed of the light propagating through the working optical line in the bypassed section. By increasing the propagation delay amount of the bypass optical line by the amount adjusting means, the propagation delay amount of the bypass optical line can be matched with the propagation delay amount of the working optical line in the bypassed section. A construction method and a bypass optical line system can be provided.

  This makes it easy to select a bypass optical line when performing the service uninterruptible switching technology, and it is possible to expand the application target of the service uninterrupted switching technology that minimizes the user impact.

It is a block diagram showing an example of composition of a detour optical line system constructed by a construction method concerning a 1st embodiment of the present invention. It is a comparison figure of the propagation delay amount with respect to the optical line length of a hollow optical fiber and a single mode fiber (SMF). It is a block diagram which shows the structural example of the detour optical line system constructed | assembled by the construction method which concerns on the 2nd Embodiment of this invention.

  Embodiments according to the present invention will be described below with reference to the drawings. Each embodiment described below is an example for carrying out the present invention, and the present invention is not limited to these embodiments.

(First embodiment)
FIG. 1 is a block diagram showing a configuration example of a detour optical line system constructed by the construction method according to the first embodiment of the present invention.

  That is, the detour optical line system 10 according to the present embodiment includes an active optical line 15 using an optical fiber that connects between a transmission apparatus (OLT: Optical Line Terminal) 11 and a transmission apparatus (ONU: Optical Network Unit) 12. A bypass optical line 16 is provided in the bypass section B.

  Both ends of the detour optical line 16 are connected to the in-house optical coupler 13 at the detour start end S in the working optical line 15 and the outside optical coupler 14 at the detour end E in the working optical line 15, respectively.

  A propagation delay amount adjusting unit 17 that adjusts the propagation delay amount of a signal propagating through the detour optical line 16 is provided in the middle of the detour optical line 16. A propagation delay amount measuring unit 18 is connected to the in-house optical coupler 13.

  The propagation delay amount adjusting unit 17 controls the delay of the optical signal by converting the optical signal propagating through the detour optical line 16 into an electric signal, and converts the optical signal into an optical signal again by the electric-optical conversion and emits it. At this time, the wavelength of the emitted optical signal is set to the test light wavelength so as not to affect the communication. In order to realize this, a filter (not shown) that blocks test light having a test light wavelength is installed in the OLT 11 and the ONU 12. The communication light propagating through the working optical line 15 and the test light are combined by the in-house optical coupler 13, and the combined signal is input to the propagation delay amount measuring unit 18.

  The propagation delay amount measuring unit 18 measures the propagation delay difference of the detour optical line 16 with respect to the working optical line 15 in the delay section B by using two methods in combination as described below. That is, as described in Non-Patent Document 3, the first method measures the propagation delay difference of the detour optical line 16 with respect to the working optical line 15 in the delay section B from the similarity (correlation) of the signal pattern. It is a method. The second method detects the phase difference between the signal propagating through the working optical line 15 in the delay section B and the signal propagating through the detour optical line 16, and based on this phase difference, the working optical line in the delay section B This is a method called a fine measurement method for measuring the propagation delay difference of the detour optical line 16 with respect to 15 with high accuracy.

  The propagation delay amount adjustment unit 17 propagates the detour optical line 16 by increasing the propagation delay amount of the signal propagating through the detour optical line 16 based on the propagation delay difference measured by the propagation delay amount measurement unit 18. The propagation delay amount of the signal is adjusted so as to coincide with the propagation delay amount of the signal propagating through the working optical line 15 in the delay section B.

  The propagation delay amount adjusting unit 17 can vary the propagation delay amount of the detour optical line 16 only in the positive direction by electrically adding a delay to the signal propagating through the detour optical line 16. Further, since the propagation delay amount adjusting unit 17 is composed of optical / electrical parts, it has a unique propagation delay amount.

  Therefore, in order to make the optical line duplex, the total propagation delay amount by the detour optical line 16 and the propagation delay amount adjusting unit 17 needs to be smaller than the propagation delay amount of the working optical line 15 in the detour section B. .

  For this reason, the detour optical line 16 is configured by a low refractive index medium having a lower refractive index than the optical fiber used for the working optical line 15, for example, a hollow optical fiber 19. The detour optical line 16 does not necessarily have to be a low refractive index medium like the hollow optical fiber 19, and most of the detour optical line 16 is the same optical fiber as the working optical line 15, and only a part thereof is the hollow optical fiber 19. You may comprise by replacing with. In FIG. 1, a hollow optical fiber 19 is used for the detour optical line 16 on the outside optical coupler 14 side, and other than that, the optical fiber such as a single mode fiber (SMF) having the same specifications as the working optical line 15 is used. The example which uses is shown.

  FIG. 2 is a comparison diagram of propagation delay amounts (μs: microseconds) with respect to the optical line length (km) of the hollow optical fiber 19 and the single mode fiber (SMF).

  In FIG. 2, the optical transmission line is a hollow optical fiber 19 and the refractive index of air is calculated as a refractive index: 1.0003. The light propagation delay amount a is calculated using S0003, and the optical transmission line is SMF. The propagation delay amount b of light calculated using .4671 and the propagation delay amount difference c which is the difference between the propagation delay amount b and the propagation delay amount a are shown. The wavelength of light is 1310 nm.

  The slopes of the propagation delay amount a and the propagation delay amount b indicate the propagation speed (so-called group speed), the light speed in the hollow optical fiber 19 is 299702547.2 (m / s), and the light speed in the SMF is 204340852.4. (M / s).

  As shown in FIG. 2, the propagation delay difference c increases in proportion to the optical line length. That is, the propagation speed is faster and the propagation delay amount is lower in the hollow optical fiber 19 than in the SMF. Accordingly, even if the majority of the bypass optical line 16 is an optical fiber (for example, SMF) having the same specifications as that of the active optical line 15, while the remaining part of the bypass optical line 16 is a hollow optical fiber 19, the active ray in the bypass section B is used. The propagation delay amount in the detour optical line 16 can be made lower than the propagation delay amount in the path 15.

  When the result of FIG. 2 is used, for example, when the length of the bypass section B (that is, the optical line length in FIG. 2) is 8 km and the fixed delay amount of the propagation delay amount adjusting unit 17 is 4 μs, the bypass optical line Propagation of the working optical line 15 having an optical line length of 8 km by making the hollow optical fiber 19 of 2 km or more of 16 and the SMF having the same specification as that of the working optical line 15 of the remainder of the bypass optical line 16, that is, 6 km or less. The total propagation delay amount of the detour optical line 16 having an optical line length of 8 km (of which 2 km or more is the hollow optical fiber 19 and 6 km or less is SMF) and the propagation delay amount adjusting unit 17 is greater than the delay amount. Lower.

  Then, the propagation delay amount adjusting unit 17 delays the signal propagating through the bypass optical line 16, thereby reducing the propagation delay amount of the signal passing through the bypass section B via the bypass optical line 16 and the propagation delay amount adjusting unit 17. The propagation delay amount of the signal propagating in the same section via the working optical line 15 is matched. As a result, even if the working optical line 15 is switched to the detour optical line 16, the propagation delay amount is the same. Therefore, the signal can be duplicated without affecting the communication, and the communication is maintained, that is, in-service. Thus, it is possible to construct the detour optical line 16 that enables uninterrupted disconnection from the working optical line 15.

  In addition, according to the detour optical line system 10 according to the present embodiment, since the propagation delay amount of the detour optical line 16 can be reduced, the current use in the detour section B, which is a precondition of the conventional uninterruptible switching method. The restriction that the length of the detour optical line 16 must be shorter than the length of the optical line 15 is relaxed, and it is possible to expand the application area that enables switching without interruption in service. Become.

(Second Embodiment)
FIG. 3 is a block diagram showing a configuration example of the detour optical line system 30 constructed by the construction method according to the second embodiment of the present invention.

  Since the present embodiment is a modification of the first embodiment, only the differences from the first embodiment will be described below, and the same portions are denoted by the same reference numerals in FIG. 3 to avoid redundant description. .

  In other words, the detour optical line system 30 shown in FIG. 3 differs from FIG. 1 in that the hollow optical fiber 19 is not used in the detour optical line 16 and the outside optical coupler 31 is used instead of the outside optical coupler 14. It is a point that is applied.

  That is, an optical fiber (for example, SMF) having the same specifications as the working optical line 15 is used for the bypass optical line 16.

  In the present embodiment, the working optical line 15 in the bypass section B is longer than the bypass optical line 16 in the section. Then, this long portion is inserted into the in-house optical coupler 13 or the off-site optical coupler 31 as the extra-length fiber 32 or bundled in the vicinity thereof. FIG. 3 shows an example of this, and the extra length fiber 32 is inserted into the off-site optical coupler 31.

  The outside optical coupler 31 has the same configuration as the outside optical coupler 14 shown in FIG. 1 except that the outside optical coupler 31 has a space in which the extra length fiber 32 can be inserted.

  With such a configuration, the detour optical line system 30 shown in FIG. 3 also has the detour optical line 16 more than the propagation delay amount of the working optical line 15 in the detour section B, similarly to the detour optical line system 10 shown in FIG. The propagation delay amount is reduced.

  However, the detour optical line system 10 shown in FIG. 1 uses a hollow optical fiber 19 having a low refractive index as a part of the detour optical line 16 to increase the light propagation speed in the detour optical line 16. .

  On the other hand, in the detour optical line system 30 shown in FIG. 3, the detour optical line 16 uses an optical fiber having the same specifications as the work optical line 15, but is detoured more than the length of the work optical line 15 in the detour section B. This is realized by shortening the length of the optical line 16.

  Even with such a configuration, similarly to the first embodiment, the propagation delay amount adjusting unit 17 delays the signal propagating through the detour optical line 16, so that the detour optical line 16 and the propagation delay amount adjusting unit 17 are changed. Therefore, the propagation delay amount of the signal passing through the bypass section B can be made to coincide with the propagation delay amount of the signal propagating through the section via the working optical line 15.

  As a result, even if the working optical line 15 is switched to the detour optical line 16, the propagation delay amount is the same. Therefore, the signal can be duplicated without affecting the communication, and the communication is maintained, that is, in-service. Thus, it becomes possible to construct the detour optical line 16 that enables the working optical line 15 to be disconnected without instantaneous interruption.

  In order to realize the detour optical line system 30 as described above, it is assumed that the length of the working optical line 15 must be secured in advance so that the extra length fiber 32 can be formed. However, it is not necessary to apply the hollow optical fiber 19 as shown in FIG. 1, and the detour optical line 16 can be composed of all optical fibers having the same specifications as the working optical line 15, so that the configuration can be simplified. is there.

  The present invention is not limited to the above embodiments. For example, in the first embodiment, a part of the bypass optical line 16 is the hollow optical fiber 19. However, the optical fiber 19 is limited to the hollow optical fiber 19 as long as it is a light propagation medium having a refractive index lower than that of the working optical line 15. It is not something that can be done.

  Further, FIG. 1 shows an example in which the hollow optical fiber 19 is provided on the outside optical coupler 14 side. However, the hollow optical fiber 19 may be provided on the in-house optical coupler 13 side or the detour optical line 16. The both ends of the hollow optical fiber 19 may be formed of optical fibers having the same specifications as the working optical line 15.

  3 shows an example in which the extra-length fiber 32 is inserted into the outside optical coupler 31, but it may be inserted into the inside optical coupler 13.

  In addition, various combinations and modifications can be implemented with various modifications without departing from the spirit of the present invention.

  In short, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

DESCRIPTION OF SYMBOLS 10 Detour optical line system, 11 Transmission apparatus, 12 Transmission apparatus, 13 In-house optical coupler, 14 Outside optical coupler, 15 Current optical line, 16 Detour optical line, 17 Propagation delay amount adjustment part, 18 Propagation delay amount measurement part, 19 Hollow optical fiber, 30 detour optical line system, 31 off-site optical coupler, 32 extra-length fiber.

Claims (4)

A method of constructing a detour optical line for an active optical line connecting between transmission devices,
Connecting both ends of the detour optical line to a pair of optical couplers respectively connected to the detour start end and detour end end in the working optical line;
Providing a propagation delay amount adjusting means for adjusting a propagation delay amount of a signal propagating through the detour optical line in the middle of the detour optical line,
The working optical line and the detour optical line are optical fibers of the same specification,
By making the length of the detour optical line from the detour start end to the detour end end shorter than the length of the working optical line from the detour start end to the detour end end, the detour start end to the detour end end Propagate the total propagation delay amount of the signal propagating through the detour optical line to the detour end end by the detour optical line and the propagation delay amount adjusting unit from the detour start end to the detour end end. smaller than the propagation delay of a signal,
Among the working optical lines from the detour start end to the detour end end, a working optical line portion longer than the detour optical line from the detour start end to the detour end end is the detour start end or the detour end. A method of constructing a detour optical line that is bundled in the vicinity of the end . By delaying the signal propagating through the detour optical line by the propagation delay amount adjusting means, the detour optical line and the propagation delay of the signal propagating through the detour optical line from the detour start end to the detour end end A total amount of propagation delay by the amount adjusting means is matched with a propagation delay amount of a signal propagating through the working optical line from the detour start end to the detour end end, so that the detour from the working optical line in service The detouring optical line construction method according to claim 1 , wherein switching to an optical line without interruption is possible. A detour optical line system comprising a detour optical line for a working optical line connecting between transmission devices,
A detour optical line having both ends connected to a pair of optical couplers respectively connected to a detour start end and a detour end in the working optical line;
Propagation delay amount adjusting means for adjusting a propagation delay amount of a signal that is provided in the middle of the bypass optical line and propagates through the bypass optical line,
The working optical line and the detour optical line are optical fibers of the same specification,
By making the length of the detour optical line from the detour start end to the detour end end shorter than the length of the working optical line from the detour start end to the detour end end, the detour start end to the detour end end Propagate the total propagation delay amount of the signal propagating through the detour optical line to the detour end end by the detour optical line and the propagation delay amount adjusting unit from the detour start end to the detour end end. smaller than the propagation delay of a signal,
Among the working optical lines from the detour start end to the detour end end, a working optical line portion longer than the detour optical line from the detour start end to the detour end end is the detour start end or the detour end. A detour optical line system that is bundled near the end . By delaying the signal propagating through the detour optical line by the propagation delay amount adjusting means, the detour optical line and the propagation delay of the signal propagating through the detour optical line from the detour start end to the detour end end A total amount of propagation delay by the amount adjusting means is matched with a propagation delay amount of a signal propagating through the working optical line from the detour start end to the detour end end, so that the detour from the working optical line in service The detour optical line system according to claim 3 , which enables uninterrupted switching to an optical line.

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