Fiber optic anomaly detection system

Abstract

To provide an optical fiber abnormality detection system that can accurately detect abnormality of an optical fiber.SOLUTION: An optical fiber abnormality detection system 1 is a system that can detect abnormality of a multimode optical fiber, the system being mainly constituted of light sources 3, optical fibers 17a and 17b, a light detection part 9, a control unit 11 and the like. One ends of the optical fibers 17a are each connected to the plurality of light sources 3. Furthermore, the another optical fibers 17b are each connected to the other ends of the optical fibers 17a with fusion-spliced parts 7. The light detection part 9 is disposed in the vicinity of the fusion-spliced parts 7. The light detection part 9 is, for example, a photodiode that can detect light leaking from the optical fibers 17a and 17b (fusion-spliced parts 7). The light detection part 9 is, for example, disposed at the outside of a housing 19 with a light detecting face exposed inside the housing 19.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical fiber abnormality detection system capable of detecting an abnormality in a multimode optical fiber. [Background Art]

[0002] For example, an optical module incorporating a plurality of optical fibers is used. In such a module, for example, if an abnormality occurs at a fusion-spliced portion between predetermined optical fibers, this not only damages the relevant site, but also affects the fusion-spliced portions between adjacent optical fibers, requiring a great number of man-hours for repairs and the like.

[0003] For this reason, there is a demand for an abnormality detection system that can immediately detect an abnormality when an abnormality occurs in a predetermined optical fiber.

[0004] As such a means for detecting an abnormality, for example, a fiber fuse detection device that detects light resulting from the occurrence of a fiber fuse has been proposed (see, for example, Patent Document 1). [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 2021-89191 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] However, the method of Patent Document 1 cannot be applied in the case of an abnormality that is not accompanied by the occurrence of a fiber fuse. For example, in a multimode high-power light source, a fiber fuse does not occur, and burning that includes the coating from the fiber end face progresses, making it difficult to apply the method of Patent Document 1.

[0007] This invention has been made in view of the above problems, and aims to provide an anomaly detection system capable of accurately detecting anomalies in multimode optical fibers. [Means for solving the problem]

[0008] To achieve the aforementioned objectives, the present invention provides an anomaly detection system capable of detecting anomalies in multimode optical fibers, comprising: a light source; and a plurality of multimode optical fibers, one end of which is optically connected to the light source and which are arranged at intervals from one another. , and the fusion splice portions of each of the optical fibers, which are arranged at intervals from each other, The aforementioned Fusion splice The system comprises a light detection unit capable of detecting light leaking from the optical fiber, and a control unit that stops all light sources connected to the optical fiber when the amount of light detected by the light detection unit exceeds a predetermined value. The light emitted from the aforementioned light source is light that does not generate fiber fuses. The wavelength of light detected by the light detection unit and the wavelength of light emitted from the light source are the same. This is an optical fiber anomaly detection system characterized by [the following feature].

[0009] The optical fibers are fixed on the heat dissipation member at predetermined intervals, and it is desirable that the fusion splice portion of each optical fiber is positioned on the heat dissipation member.

[0010] Preferably, a housing covering the fusion splice is fixed to the heat dissipation member, and the light sensing unit is positioned so that its light sensing surface is exposed inside the housing.

[0011] It is desirable that the inner surface of the housing be treated with a coloring or roughening process that can improve light absorption.

[0012] Heat dissipation fins may be provided on the outer surface of the housing.

[0013] The housing is provided with a position adjustment mechanism that allows for adjustment of the position of the light detection unit. The position adjustment mechanism is configured to allow the light detection unit to slide in a groove provided in the housing and be fixed in any position, and to shield the groove. That's fine.

[0014] For multiple fusion splices, one The aforementioned light detection unit but , the fusion splice Rather It is preferable that it be placed on the light source side.

[0015] In the fusion splice, optical fibers of the same diameter are connected to each other. The fusion splicing portion may be coated with a light absorbing resin.

[0016] In the fusion splicing portion, the optical fibers having different diameters may be connected to each other.

[0017] The light emitted from the light source may be light that does not cause fiber fuse.

[0018] In this case, the light source may be a semiconductor laser capable of emitting multimode laser light, and further, the light source may have a core diameter of 100 µm or more and a power density of 5.0×10 6 W / cm 2 The light source may be a semiconductor laser capable of emitting the following light.

[0019] The wavelength of light detected by the light detection unit and the wavelength of light emitted from the light source may be the same.

[0020] In this case, the light may be blue light, or the light may be infrared light.

[0021] According to the present invention, when an abnormality occurs in a multimode optical fiber, instead of detecting light that propagates toward the light source along the core of the optical fiber such as that generated by fiber fuse, light leaking to the outside from the abnormal portion (burned portion) of the optical fiber is directly detected, thereby enabling detection of light having the same wavelength as the light propagating inside the optical fiber. As described above, since a light detection unit capable of detecting the same wavelength as that of the light source can be used, leaked light can be detected with high accuracy.

[0022] Further, if fusion splicing portions of a plurality of optical fibers are arranged on a heat radiating member, heat generated due to loss at the fusion splicing portions can be efficiently radiated.

[0023] Furthermore, by using a housing that covers the fusion splice, stray light leakage to the outside can be suppressed. Also, by placing the light detection unit outside the housing, the thermal effects on the light detection unit can be suppressed.

[0024] Furthermore, by applying a coloring or roughening treatment to the inner surface of the housing to improve light absorption, light reflection can be suppressed, increasing the signal-to-noise ratio during abnormal conditions, and allowing the light to be absorbed and dissipated as heat to the outside.

[0025] Furthermore, by providing heat dissipation fins on the outer surface of the casing, the heat absorbed by the casing can be efficiently dissipated.

[0026] Furthermore, by enabling adjustment of the position of the light detection unit, for example, the distance from the fusion splice to the detection surface of the light detection unit can be appropriately adjusted. This allows for appropriate adjustment of the detection sensitivity of the detection unit in response to abnormalities in the fusion splice.

[0027] Furthermore, if the fusion splice fails, the fused fiber section will advance toward the light source. Therefore, by positioning the photodetector on the light source side relative to the fusion splice, the damaged section can be made to advance toward the photodetector in the event of an abnormality, thereby improving detection accuracy.

[0028] Furthermore, by applying a light-absorbing resin to the fusion splice, leaked light during normal operation can be absorbed. This improves the signal-to-noise ratio during abnormal operation.

[0029] The effects described above are particularly effective in detecting anomalies when fusion splicing optical fibers of different diameters.

[0030] Furthermore, the present invention can detect abnormalities even when fiber fuses do not occur. For example, a semiconductor laser capable of emitting multimode light can be used as a light source, and it can also be applied to light with a core diameter above a predetermined level and a light density below a predetermined level.

[0031] Furthermore, by making the wavelength of the light source the same as the wavelength used for fault detection, the sensitivity of the light detection unit can be limited. It can also be used to detect stray light during normal operation, and this can be used to implement a laser stop function based on the lower limit judgment of the light detection unit. [Effects of the Invention]

[0032] According to the present invention, it is possible to provide an optical fiber anomaly detection system that can accurately detect anomalies in optical fibers. [Brief explanation of the drawing]

[0033] [Figure 1] A schematic diagram showing the optical fiber anomaly detection system 1, where (a) is a lateral cross-sectional view and (b) is a plan view. [Figure 2] A schematic diagram showing another embodiment of the optical fiber anomaly detection system 1. [Figure 3] Enlarged view of section A in Figure 1(a). [Modes for carrying out the invention]

[0034] The optical fiber anomaly detection system according to an embodiment of the present invention will be described below. Figure 1 is a schematic diagram showing the configuration of the optical fiber anomaly detection system 1, where Figure 1(a) is a side cross-sectional view and (b) is a plan view (perspective view of the housing 19). The optical fiber anomaly detection system 1 is a system capable of detecting anomalies in multimode optical fibers and mainly consists of a light source 3, optical fibers 17a and 17b, an optical detection unit 9, a control unit 11, etc.

[0035] As the light source 3, any device capable of emitting light that does not cause fiber fusion can be applied. For example, the light source 3 is a semiconductor laser capable of emitting multimode laser light. In this case, the light source 3 has a core diameter of 100 μm or more and a power density of 5.0 × 10⁻¹⁶ 6 W / cm 2 A semiconductor laser capable of emitting the following types of light can be applied.

[0036] One end of an optical fiber 17a is connected to each of the multiple light sources 3. The other end of each optical fiber 17a is connected to another optical fiber 17b via a fusion splice 7. In other words, the multiple optical fibers 17a, each connected to one end of a light source 3, and the multiple optical fibers 17b connected to each of the optical fibers 17a are arranged at intervals from one another. Note that the optical fibers 17a and 17b are multimode optical fibers.

[0037] Here, the optical fibers 17a and 17b may have the same diameter, or they may have different diameters. In other words, optical fibers 17a and 17b of different diameters may be connected to each other in the fusion splice 7.

[0038] In this embodiment, we will describe in particular a method for detecting abnormalities in the fusion splice 7 of the optical fibers 17a and 17b, but the same configuration can be applied not only to the fusion splice 7 but also to the routing portion of the optical fiber, such as the excess length portion.

[0039] Adjacent optical fibers 17a and 17b are fixed on the heat dissipation member 5 with a predetermined interval between them. That is, the fusion splice 7 of each optical fiber 17a and 17b are positioned on the heat dissipation member 5. For example, multiple V-grooves are formed on the heat dissipation member 5 at predetermined intervals, and the optical fibers 17a and 17b are fixed to the V-grooves. Heat dissipation fins 15 are formed on the heat dissipation member 5, and heat can be efficiently dissipated to the outside by the heat dissipation fins 15.

[0040] Furthermore, the housing 19 is fixed to the heat dissipation member 5 so as to cover all of the fusion splice connections 7. By covering the fusion splice connections 7 with the housing 19, leakage light (stray light) to the outside can be suppressed. The housing 19 is fixed to the heat dissipation member 5 with screws or the like.

[0041] Here, it is desirable to select a material for the housing 19 that has high absorption of leaked light. For example, for blue wavelength light, it is desirable to make the housing 19 out of copper. By doing so, for example, the slight leak of light from the fusion splice 7 during normal operation is suppressed from being reflected within the housing 19, and the light is absorbed and converted into heat, which is then dissipated to the outside via the heat dissipation member 5, etc. In addition, heat dissipation fins 13 may be provided on the outer surface of the housing 19 to further improve the heat dissipation characteristics.

[0042] Furthermore, in order to more efficiently absorb light (convert it to heat) by the housing 19, the inner surface of the housing 19 may be treated with coloring or roughening that can improve light absorption. By doing so, even slight light leakage from the fusion splice 7 during normal operation can be absorbed, and the signal-to-noise ratio during abnormal operation can be increased.

[0043] A photodetector 9 is positioned near the fusion splice 7. The photodetector 9 is, for example, a photodiode capable of detecting light leaking from the optical fibers 17a and 17b (fusion splice 7). The photodetector 9 is positioned outside the housing 19, for example, such that its photodetector surface is exposed inside the housing 19.

[0044] Here, instead of placing a light detection unit 9 for each optical fiber, a single light detection unit 9 can simultaneously detect abnormalities in multiple optical fibers 17a, 17b (fusion splice 7). For example, as shown in Figure 1(b), one light detection unit 9 can be placed in the center in the direction of the optical fiber 17a (up and down direction in Figure 1(b)). Note that multiple light detection units 9 may be provided.

[0045] The wavelength of light detected by the light detection unit 9 and the wavelength of light emitted from the light source 3 can be the same. For example, the light emitted from the light source 3 may be blue light (wavelength 400-500 nm). Alternatively, the light emitted from the light source 3 may be infrared light (wavelength 1000-1100 nm).

[0046] As mentioned above, if an abnormality occurs in the optical fibers 17a and 17b (fusion splice 7), heat prevents the confinement of light within the core, causing a large amount of light to leak out from the optical fibers 17a and 17b (fusion splice 7). The light detection unit 9 detects this light, and if the amount of light (light intensity) detected by the light detection unit 9 exceeds a predetermined value, the control unit 11 stops all light sources 3 connected to the optical fiber 17a. Therefore, if an abnormality occurs in one optical fiber 17a or 17b (fusion splice 7), the device can be stopped before it affects the other healthy optical fibers 17a and 17b (fusion splice 7).

[0047] If the light detection unit 9 is placed directly above the fusion splice 7, it becomes more susceptible to the effects of light leakage during normal operation. Furthermore, the difference in distance (distance ratio) between the optical fibers 17a and 17b (fusion splice 7) approximately in the center of the coordinating direction and the optical fibers 17a and 17b (fusion splice 7) at both ends of the coordinating direction becomes larger. Therefore, it is desirable to place the light detection unit 9 in a position offset in a direction perpendicular to the coordinating direction of the optical fibers 17a and 17b (the left-right direction in Figure 1(b)).

[0048] In this case, it is desirable to position the light detection unit 9 offset from the fusion splice 7 towards the light source 3 side (left side in Figure 1(b)). When an abnormality occurs in the optical fibers 17a and 17b (fusion splice 7) and the abnormal area spreads, the abnormal area spreads towards the light source 3 side. By positioning the light detection unit 9 offset towards the light source 3 side in this way, the abnormal area can be directed towards the light detection unit 9. This improves the accuracy of light detection.

[0049] Furthermore, another light detection unit capable of detecting light intensity may be provided downstream of the optical fiber 17b, and an abnormality may be detected when the light intensity detected by the other light detection unit falls below a predetermined level. In this case, the control unit 11 may control the system to stop the light source 3 as an abnormality when the light intensity detected by the light detection unit 9 falls above a predetermined level, or when the light intensity detected by the other light detection unit falls below a predetermined level.

[0050] As described above, according to this embodiment, abnormalities in the optical fiber can be detected even in cases where fiber fusion does not occur, such as with multimode laser light sources. In particular, when an abnormality occurs in the fusion splice 7 of the optical fiber, light leaking from the core can be directly detected, thereby detecting light of the same wavelength as the light emitted from the light source 3. Therefore, since the light detection unit 9 does not need to measure light over a wide wavelength range, leakage light can be detected efficiently.

[0051] Furthermore, in this case, even slight light leakage that occurs during normal operation may worsen the accuracy of light leakage detection during abnormal operation. However, by suppressing light reflection inside the housing 19 and positioning the light detection unit 9 away from the fusion splice 7, the effects of light leakage during normal operation can be suppressed.

[0052] Furthermore, when the housing 19 absorbs light, it is converted into heat, but by dissipating this heat to the outside using the heat dissipation member 5 (heat dissipation fin 15) and heat dissipation fin 13, the thermal impact on the internal fusion splice joint 7 and other parts can be suppressed.

[0053] It should be noted that the present invention is not limited to the embodiment shown in Figure 1. For example, if shielding of stray light or absorption of leaked light is not required, the housing 19 is not essential. Also, if sufficient heat dissipation characteristics are available, the heat dissipation members (heat dissipation fins 13, 15) are not essential.

[0054] Furthermore, the placement of the light detection unit 9 is fixed near the end of the housing 19 on the light source 3 side, as shown in Figure 1, but is not limited to this. Figure 2 shows another configuration of the optical fiber anomaly detection system 1. In the example shown in Figure 2, the housing 19 is provided with a position adjustment mechanism that allows the position of the light detection unit 9 to be adjusted. The position adjustment mechanism allows the light detection unit 9 to be slid in a groove provided in the housing 19 and fixed in any position, and is configured so that the groove being slid is shielded.

[0055] In this case, for example, by making the photodetector 9 movable in the axial direction of the optical fibers 17a and 17b (left-right direction in Figure 2), the distance from the fusion splice 7 to the photodetector surface of the photodetector 9 can be adjusted. In other words, the distance between the abnormal part and the photodetector 9 when an abnormality occurs can be adjusted. Therefore, the photodetection sensitivity of the photodetector 9 can be adjusted.

[0056] For example, as mentioned above, if the light detection unit 9 is brought closer to the fusion splice 7, the distance from the abnormal area decreases, allowing for a higher light intensity to be detected during abnormal conditions, but it becomes more susceptible to interference from non-abnormal conditions. On the other hand, if the light detection unit 9 is moved further away from the fusion splice 7, the interference from non-abnormal conditions can be reduced. However, since light reflection is suppressed and light is absorbed on the inner surface of the housing 19, the light intensity of the leaked light that occurs during abnormal conditions decreases as it moves further away from the abnormal area. Therefore, there is a risk that the light intensity detected during abnormal conditions will decrease.

[0057] Therefore, by setting the position of the light detection unit 9 to an appropriate position according to, for example, the light intensity incident from the light source 3 to the optical fiber 17a, or the amount of light leakage when there is no abnormality, it is possible to detect abnormalities with high sensitivity.

[0058] Furthermore, Figure 3 is an enlarged view of part A in Figure 1(a). As shown in Figure 3, the light-absorbing resin 21 may be applied to cover a predetermined area of ​​the heat dissipation member 5, including the fusion splice 7. The light-absorbing resin 21 is, for example, a silicone-based heat dissipation resin. The light-absorbing resin 21 is a resin that can absorb slight light leakage from the fusion splice 7 during normal operation, convert it into heat, and dissipate the heat to the heat dissipation member 5. In the event of an abnormality, the light-absorbing resin will immediately burn out due to the high temperature, so it will not interfere with the detection of light leakage by the light detection unit 9.

[0059] By converting light into heat and dissipating it using the light-absorbing resin 21, it is possible to suppress light leakage during non-abnormal conditions and improve the signal-to-noise ratio (S / N ratio) for light leakage during abnormal conditions.

[0060] Although embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the embodiments described above. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0061] 1… Fiber optic anomaly detection system 3……Light source 5… Heat dissipation components 7. Fusion splice 9. Light detection unit 11... Control Unit 13… Heat dissipation fins 15… Heat dissipation fins 17a, 17b... Optical fiber 19……… cabinet 21………Light-absorbing resin

Claims

1. An anomaly detection system capable of detecting anomalies in multimode optical fibers, Light source and A plurality of multimode optical fibers, one end of which is optically connected to the light source and arranged at intervals from one another, Each of the fusion splice sections of the optical fibers is arranged at intervals from each other, A photodetector capable of detecting light leaking from the fusion splice, A control unit that stops all light sources connected to the optical fiber when the amount of light detected by the light detection unit exceeds a predetermined value, It is equipped with, The light emitted from the aforementioned light source is light that does not generate fiber fuses. An optical fiber anomaly detection system characterized in that the wavelength of light detected by the light detection unit is the same as the wavelength of light emitted from the light source.

2. The optical fibers are fixed on the heat dissipation member at predetermined intervals. The optical fiber anomaly detection system according to claim 1, characterized in that each of the fusion splice portions is arranged on the heat dissipation member.

3. The optical fiber anomaly detection system according to claim 2, characterized in that a housing covering the fusion splice is fixed to the heat dissipation member, and the optical detection unit is arranged so that its optical detection surface is exposed inside the housing.

4. The optical fiber anomaly detection system according to claim 3, characterized in that the inner surface of the housing is subjected to a coloring or roughening treatment that can improve light absorption.

5. The optical fiber anomaly detection system according to claim 3, characterized in that heat dissipation fins are provided on the outer surface of the housing.

6. The optical fiber anomaly detection system according to claim 3, characterized in that the housing is provided with a position adjustment mechanism that can adjust the position of the light detection unit, the position adjustment mechanism can slide the light detection unit in relation to a groove provided in the housing and fix it at any position, and the groove is shielded.

7. The optical fiber anomaly detection system according to claim 1, characterized in that one of the optical detection units is positioned on the light source side of the fusion splice for each of the multiple fusion splice units.

8. The optical fiber anomaly detection system according to claim 2, characterized in that optical fibers of the same diameter are connected at the fusion splice, and a light-absorbing resin is applied to the fusion splice.

9. The optical fiber anomaly detection system according to claim 1, characterized in that optical fibers of different diameters are connected in the fusion splice.

10. The optical fiber anomaly detection system according to claim 1, characterized in that the light source is a semiconductor laser capable of emitting multimode laser light.

11. The light source has a core diameter of 100 μm or more and a power density of 5.0 × 10⁻¹⁴ ６ W / cm ２ The optical fiber anomaly detection system according to claim 10, characterized in that it is a semiconductor laser capable of emitting the following light.

12. The optical fiber anomaly detection system according to claim 1, characterized in that the light is blue light.

13. The optical fiber anomaly detection system according to claim 1, characterized in that the aforementioned light is infrared light.

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