JP5993339B2 - Signal light acquisition structure, signal light measurement device, and signal light acquisition method - Google Patents

Description

  The present invention relates to a signal light acquisition structure, a signal light measurement device, and a signal light acquisition method.

  Patent Document 1 discloses a method for identifying a specific optical fiber from among a plurality of optical fibers. In this method, a specific optical fiber is identified by detecting a fiber identification data signal included in an optical signal propagating through the optical fiber. Therefore, in this method, the optical fiber is refracted to extract an optical signal from the side surface of the optical fiber, and the optical signal is detected by a photodiode.

JP 2010-529466 Gazette

  A technique for measuring a part of the signal light by leaking and extracting a part of the signal light from the side surface of the optical fiber that propagates the signal light has been studied. In order to extract such signal light, in Patent Document 1, the optical fiber is refracted to bend, and leaked light from the bent portion is detected. In this method, in order to obtain a certain degree of detection accuracy, the bending angle must be increased to leak a required amount of signal light. On the other hand, if the bending angle is increased too much, the signal light inside the optical fiber is leaked. There is a trade-off that loss can increase and interfere with communication. However, since the amount of leaked signal light and bending loss vary depending on the type of optical fiber that propagates the signal light and manufacturing variations, it is difficult to solve such a trade-off.

  The present invention has been made in view of such problems, and reduces the influence of variations in the amount of leaked signal light and bending loss due to the types of optical fibers and manufacturing variations, and the required size. An object of the present invention is to provide a signal light acquisition structure, a signal light measurement device, and a signal light acquisition method capable of preventing an excessive increase in optical loss inside an optical fiber while leaking the signal light.

  In order to solve the above-described problems, a signal light acquisition structure according to the present invention is a signal light acquisition structure for leaking and extracting a part of signal light from a side surface of a measured fiber that propagates signal light. A bend imparting member that imparts a bend to the measured fiber by contacting the measured fiber at a predetermined contact position of the measurement fiber, and a measured value at the first gripping position that is located behind the contact position in the propagation direction of the signal light A first gripping portion for controlling the bending angle of the measured fiber in the bending imparting member by gripping the fiber and being movable in a direction intersecting the optical axis direction of the measured fiber; The second gripping part that grips the fiber to be measured at the second gripping position that is located in front of the propagation direction of the fiber is opposed to the side surface of the fiber to be measured with a gap. Has an end face, characterized in that it comprises a measuring fiber for propagating signal light partially incident on one end face and leaking from the side of the measured fiber by bending the fiber to be measured by bending applying member.

  In this signal light acquisition structure, a bend imparting member is brought into contact with the measured fiber gripped by the first and second gripping portions, whereby a bend of a predetermined angle is imparted to the measured fiber. The first gripping portion can be moved in a direction intersecting the optical axis direction of the measured fiber, and the bending angle of the measured fiber is arbitrarily changed by changing the position of the first gripping portion. be able to. Therefore, for example, when the measured fiber has a relatively large bending loss (that is, a large amount of leakage light), the bending angle is reduced to suppress an excessive increase in bending loss, and the measured fiber has a relatively small bending loss. When the leakage light amount is small, the required leakage light intensity can be obtained by increasing the bending angle. As described above, according to the above signal light acquisition structure, the influence of the variation in the amount of leaked signal light and the bending loss due to the type of fiber to be measured, manufacturing variations, etc. is reduced, and the required amount of signal light is obtained. It is possible to prevent an excessive increase in optical loss inside the measured fiber while leaking light.

  In the signal light acquisition structure, the one end surface of the measurement fiber is opposed to the side surface of the measured fiber with a gap. On the other hand, for example, a method of applying a refractive index matching agent (grease) between the measurement fiber and the fiber to be measured is conceivable, but in order to stably apply and manage the refractive index matching agent at the work site. High skills are required for individual workers. Further, it is necessary to wipe off the refractive index matching agent after measuring the signal light, but it is extremely difficult to wipe it off completely. By causing the measurement fiber and the side surface of the measured fiber to face each other with a gap as in the signal light acquisition structure described above, the above-described problem can be avoided. Further, for example, a method in which the measurement fiber is brought into contact with the side surface of the fiber to be measured is conceivable. However, in such a method, the fiber to be measured may be pressed to increase the optical loss. By making the measurement fiber and the side surface of the measured fiber face each other with a gap as in the above signal light acquisition structure, it is possible to suitably acquire the signal light while suppressing optical loss in the measured fiber.

  Further, the signal light acquisition structure forms an angle θ1 (where θ1> 0 °) with respect to the first optical axis direction of the measured fiber from the first gripping position to the contact position, and the second gripping The optical axis of the measurement fiber is first with respect to the direction perpendicular to the reference line that forms an angle θ2 (where θ2 ≧ 0 °) with respect to the second optical axis direction of the measured fiber between the position and the contact position. It may be characterized in that it is inclined toward the optical axis direction. Thus, by bringing the optical axis direction of the measurement fiber closer to the first optical axis direction of the measured fiber, it is possible to increase the ratio of the light incident on the measuring fiber out of the signal light leaked from the measured fiber. it can.

  The signal light acquisition structure further includes a ferrule attached to an end portion on one end surface side of the measurement fiber, and one end surface of the ferrule facing the side surface of the measured fiber is along a reference line Also good. As a result, it is possible to prevent the measurement target fiber from being pressed by the ferrule attached to the end of the measurement fiber, and to suppress an increase in optical loss of the measurement fiber.

  Further, the signal light acquisition structure may be characterized in that an angle θ2 formed by the second optical axis direction and the reference line is larger than 0 °. Thus, by separating the portion of the measured fiber from the second gripping position to the contact position from the one end surface of the ferrule, even if the portion is bent toward the ferrule, the measured fiber and the ferrule The increase in the optical loss of the measured fiber can be suppressed.

  Further, the signal light acquisition structure may be characterized in that the distance between the side surface of the measured fiber and the one end surface of the ferrule is 50 μm or more and 100 μm or less. When the distance is 50 μm or more, contact between the measured fiber and the ferrule can be avoided regardless of variations in the outer diameter of the measured fiber, and an increase in optical loss of the measured fiber can be suppressed. Further, according to the knowledge of the present inventor, when the distance is 100 μm or less, signal light having a required size can be made incident on the measurement fiber.

  The signal light acquisition structure may be characterized in that the bend imparting member is provided so as to be movable so as to impart a bend to the measured fiber. Thus, since the bend can be imparted by moving the bend imparting member after the first and second gripping portions are gripped by the first and second gripping portions in a state where the bend is not imparted, the work of installing the measured fiber is performed. Can be easily.

  The signal light acquisition structure further includes a bending member and a base member that supports the first and second gripping portions, and both the first gripping portion and the first and second gripping portions are measured. A fiber clamp for gripping the fiber, a fixed portion fixed to the base member so as to be rotatable about a predetermined axis that intersects the optical axis direction of the measured fiber and the movement direction of the bend imparting member, and a fiber clamp portion; It is good also as having a connecting member which connects a fiber clamp part and a fixed part mutually, making a distance with a fixed part variable. Thereby, the change in the angle and the length of the measured fiber when the bending imparting member is moved can be suitably absorbed in the first gripping part or both the first and second gripping parts. .

  The signal light acquisition structure may further include a mechanism for adjusting the position of the fixing portion along a plane including the optical axis direction of the fiber to be measured and the moving direction of the bend imparting member. Thereby, the bending angle of the measured fiber can be suitably controlled by making the fiber clamp portion movable.

  The signal light acquisition structure further includes a fiber holding portion for holding the measurement fiber, and the bend imparting member moves so as to bend the measured fiber to at least one of the bend imparting member and the fiber holding portion. A mechanism for adjusting the distance between the bending imparting member and the one end face of the measurement fiber in the state may be provided. Thereby, the interval between the side surface of the fiber to be measured and the one end surface of the measurement fiber can be adjusted to further increase the incident efficiency of the leaked light to the measurement fiber.

  The signal light acquisition structure may be characterized in that the cross-sectional shape of the contact portion of the bending imparting member with the measured fiber is an arc or an elliptical arc. Thereby, it is possible to prevent a sudden increase in bending loss with respect to an increase in the bending angle of the fiber to be measured, and to easily control the bending loss and the amount of leakage light.

  In addition, the signal light measurement apparatus according to the present invention is optically coupled to one of the signal light acquisition structures described above and the other end surface of the measurement fiber, and measures the intensity of a part of the signal light that has propagated through the measurement fiber. And a light receiving portion. According to this signal light measurement device, by providing any of the signal light acquisition structures described above, the influence of variations in the amount of leakage of signal light and bending loss in the measured fiber is reduced, and the signal light of the required size is obtained. It is possible to prevent an excessive increase in optical loss inside the measured fiber while leaking light.

  Further, the signal light acquisition method according to the present invention is a signal light acquisition method for leaking and extracting a part of signal light from the side surface of the measured fiber that propagates the signal light, and a predetermined contact position of the measured fiber. Gripping the fiber to be measured at the first and second gripping positions respectively positioned behind and in the propagation direction of the signal light with respect to the optical fiber, and bringing the bend imparting member into contact with the fiber to be measured at the predetermined contact position And bending the measured fiber by the bending applying member using the measurement fiber arranged so that one end face is opposed to the side surface of the measured fiber with a gap. A second step of causing a part of the signal light leaking from the side surface of the measured fiber to enter one end surface, and a direction intersecting the optical axis direction of the measured fiber And changing the bending angle of the fiber to be measured by moving the first gripping position, and then causing a part of the signal light leaking from the side surface of the fiber to be measured to enter the one end surface again. And

  In this signal light acquisition method, the bending angle of the measured fiber can be arbitrarily changed by moving the first gripping position in the third step in a direction intersecting the optical axis direction of the measured fiber. Therefore, in the same way as the signal light acquisition device described above, the influence of the variation in the amount of leaked signal light and bending loss due to the type of fiber to be measured and manufacturing variations is reduced, and the required amount of signal light is leaked. It is possible to prevent an excessive increase in optical loss inside the measured fiber.

  According to the signal light acquisition structure, the signal light measurement device, and the signal light acquisition method according to the present invention, it is possible to reduce the influence caused by the variation in the amount of leakage of signal light and the bending loss due to the type of optical fiber and manufacturing variations, It is possible to prevent an excessive increase in optical loss inside the optical fiber while leaking a signal light having a necessary size.

FIG. 1 is a diagram schematically showing a configuration of a signal light measurement apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an angle formed by the optical axis of the measurement fiber and one end face of the ferrule. FIG. 3 is a diagram for explaining the operation of the signal light measurement device. It is a top view which shows the specific example of a signal light acquisition structure, Comprising: The state which has not provided the bending to the to-be-measured fiber is shown. It is a top view which shows the specific example of a signal light acquisition structure, Comprising: The state which has provided the bending to the to-be-measured fiber is shown. It is sectional drawing of the bending support | pillar and base member which followed the VI-VI line shown by FIG. FIG. 7 is a diagram for explaining an example of the fiber to be measured, and shows a configuration of a general subscriber optical line. FIG. 8 is a graph showing the relationship between the distance between the side surface of the measured fiber and one end surface of the ferrule, the light receiving rate of leaked light, and the transmittance of the measured fiber.

  Hereinafter, embodiments of a signal light acquisition structure, a signal light measurement device, and a signal light acquisition method according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram schematically showing a configuration of a signal light measurement apparatus 1A according to an embodiment of the present invention. As shown in FIG. 1, the signal light measurement device 1 </ b> A of this embodiment includes a signal light acquisition structure 10. The signal light acquisition structure 10 is a structure for leaking and extracting a part of the signal light L1 from the side surface of a measurement target optical fiber core wire (hereinafter referred to as a measured fiber) 50 that propagates the signal light L1. The signal light acquisition structure 10 according to the present embodiment includes a bending column 11, a first grip 12, a second grip 13, a measurement fiber 14, and a ferrule 15.

  The bending column 11 is a bending imparting member in the present embodiment. The bending column 11 bends the measured fiber 50 by contacting the measured fiber 50 at a predetermined contact position P1 of the measured fiber 50. The shape of the cross section including the optical axis of the measured fiber 50 at the contact portion with the measured fiber 50 in the bending column 11 is an arc or an elliptical arc. FIG. 1 shows a case where the cross-sectional shape is an arc. Such a bending support | pillar 11 is suitably implement | achieved by the cylindrical member (or elliptical columnar member) which makes the direction which intersects the optical axis direction of the to-be-measured fiber 50 a center axis direction, for example. In addition, the cross-sectional shape of the bending support | pillar 11 should just be a circular arc or an elliptical arc in a contact part with the to-be-measured fiber 50, and other area | regions may be flat shape etc., for example. That is, the cross-sectional shape of the bending column 11 may be, for example, a D shape.

  A part of the fiber to be measured 50 is deformed into an arc shape (or an elliptic arc shape) by being disposed along the side surface of such a cylindrical member. At this time, the curvature of the fiber to be measured 50 is determined by the shape of the bending column 11. For example, when the cross section of the bending column 11 is an arc, the curvature of the fiber to be measured 50 is constant. Due to the bending of the measured fiber 50 by the bending support 11, a part of the signal light L <b> 2 leaks from the side surface of the measured fiber 50.

  The first gripping part 12 grips (clamps) the measured fiber 50 at a first gripping position P2 located behind the contact position P1 in the propagation direction of the signal light L1. Such a 1st holding part 12 is suitably implement | achieved by pinching the 1st holding position P2 of the to-be-measured fiber 50, for example by a pair of member which has a mutually opposing surface. Further, the first gripping portion 12 has directions B1 and B2 intersecting with the optical axis direction of the measured fiber 50 (preferably perpendicular to the optical axis direction of the measured fiber 50 and the central axis direction of the bending column 11). It is configured to be movable in a direction orthogonal to the above. By moving the first gripping portion 12 in the directions B1 and B2, the bending angle of the fiber to be measured 50 in the bending column 11 can be controlled.

  The second gripping part 13 grips (clamps) the measured fiber 50 at a second gripping position P3 that is located in front of the contact position P1 in the propagation direction of the signal light L1. Such a 2nd holding part 13 is suitably implement | achieved by pinching the 2nd holding position P3 of the to-be-measured fiber 50, for example by a pair of member which has a mutually opposing surface.

  Here, a reference line A is defined. The reference line A is a straight line extending in a direction orthogonal to the central axis direction of the columnar member (or elliptical columnar member) constituting the bending column 11, and the contact position P1 from the first gripping position P2 of the measured fiber 50. A straight line included in a plane including both the optical axis a1 of the portion between the optical fiber a1 and the optical axis a2 of the portion of the measured fiber 50 between the second gripping position P3 and the contact position P1. The reference line A forms an angle θ1 (where θ1> 0 °) with respect to the optical axis direction (first optical axis direction) of the optical axis a1. That is, the first gripping portion 12 is arranged such that a portion of the measured fiber 50 between the first gripping position P2 and the contact position P1 forms an angle θ1 with respect to the reference line A. The reference line A forms an angle θ2 (where θ2 ≧ 0 °) with respect to the optical axis direction of the optical axis a2 (second optical axis direction). In other words, the second gripping portion 13 is arranged such that a portion of the measured fiber 50 from the second gripping position P3 to the contact position P1 forms an angle θ2 with respect to the reference line A. The angle θ2 is preferably larger than 0 °. In one embodiment, the angle θ2 is 10 °.

  The measurement fiber 14 is an optical fiber having one end surface 14a and the other end surface 14b. One end surface 14 a of the measurement fiber 14 is opposed to the side surface of the measured fiber 50 with a gap G therebetween. That is, no refractive index matching agent or lens is provided between the one end surface 14a and the side surface of the measured fiber 50. The light L2 leaked from the side surface of the measured fiber 50 due to the bending of the measured fiber 50 is incident on the one end surface 14a. The measurement fiber 14 propagates the leaked light L2 thus incident. In the present embodiment, the optical axis of the measurement fiber 14 is in the direction of the optical axis a1 with respect to the direction orthogonal to the reference line A (straight line N in the drawing) in order to increase the incidence rate of the leaked light L2 on the one end surface 14a. Inclined to the side. In order to increase the incidence rate of the leakage light L2, the measurement fiber 14 is preferably a multimode fiber having a core diameter larger than that of a normal single mode fiber or the like, such as a GI (Graded Index) fiber or SI ( Step Index) fiber is preferably used.

  The ferrule 15 is a substantially columnar member attached at the end of the measurement fiber 14 on the one end face 14 a side so that the center axis thereof coincides with the center axis of the measurement fiber 14. In the present embodiment, the one end surface 15 a of the ferrule 15 that faces the side surface of the measured fiber 50 is along the reference line A, and more preferably, the one end surface 15 a is parallel to the reference line A. As described above, since the optical axis of the measurement fiber 14 is inclined with respect to the direction (straight line N) perpendicular to the reference line A, the one end surface 15a of the ferrule 15 is in relation to the optical axis of the measurement fiber 14. Will be inclined. Here, FIG. 2 is a diagram illustrating an angle θ3 formed by the optical axis of the measurement fiber 14 and the one end face 15a of the ferrule 15. In FIG. This angle θ3 is equal to, for example, the angle formed by the optical axis of the measurement fiber 14 and the reference line A. Preferably, the angle θ3 is 30 ° or less.

  Further, as will be apparent from the examples described later, the distance d between the side surface of the measured fiber 50 and the one end surface 15a of the ferrule 15 is preferably 50 μm or more, and preferably 100 μm or less.

  In addition to the signal light acquisition structure 10 described above, the signal light measurement device 1A of the present embodiment further includes a condensing lens 28 and a light receiving element 29. The light receiving element 29 is, for example, a photodiode (PD), and is preferably an avalanche photodiode (APD) (hereinafter, APD will be described as an example). The condensing lens 28 is optically coupled to the other end surface 14 b of the measurement fiber 14 and condenses the leaked light (part of the signal light L 1) L 2 emitted from the other end surface 14 b toward the APD 29. The APD 29 is a light receiving unit in the present embodiment, and is optically coupled to the other end surface 14 b of the measurement fiber 14 via the condenser lens 28. The APD 29 receives the leaked light L2 propagated through the measurement fiber 14 and generates an electrical signal corresponding to the light intensity of the leaked light L2. The APD 29 is preferably capable of high-speed operation to such an extent that a signal component (such as a MAC address signal) included in the leaked light L2 can be identified. Further, by using the above-described optical fiber having a large core diameter as the measurement fiber 14 and coupling the leaked light to the light receiving unit (APD 29) through the condensing optical system such as the condensing lens 28, the leaked light L2 can be sufficiently obtained. Is coupled to the light receiving section, and the signal component can be identified.

  FIG. 3 is a diagram for explaining the operation of the signal light measurement apparatus 1A. With reference to FIG. 3, the signal light measurement method according to the present embodiment will be described together with the operation of the signal light measurement apparatus 1A. Here, as the measured fiber 50, two types of optical fibers having different bending loss characteristics, that is, an R15 fiber and an R30 fiber will be described as an example. The R15 fiber is an optical fiber having an allowable bending radius of 15 mm, and is strong against bending and does not easily generate a large bending loss. However, since the leakage light from the bent portion is small, the leakage of a size necessary for identifying a signal is small. It is difficult to get light. Further, the R30 fiber is an optical fiber having an allowable bending radius of 30 mm, and since the leaked light from the bent portion is large, it is easy to identify the signal, but it is weak to bending and easily causes a large bending loss.

  First, as shown in FIG. 3A, the first gripping position P2 and the second gripping position P3 of the measured fiber 50 are gripped and fixed by the first gripping section 12 and the second gripping section 13. Then, the contact position P1 of the measured fiber 50 is brought into contact with the surface of the bending column 11 to bend the measured fiber 50 (first step). At this time, the bending angle of the measured fiber 50 is θ1 + θ2, and it is preferable to change the bending angle by adjusting θ1, and in this embodiment, θ1 = θ1a. In the following, in order to describe a mode in which the bending angle is adjusted by θ1, the bending angle will be referred to as θ1.

  Next, the light L2 leaked from the side surface of the measurement fiber 50 due to the bending of the measurement fiber 50 by the bending column 11 is made incident on the one end surface 14a of the measurement fiber 14 (second step). Then, the leakage light L2 is detected by the APD 29, and a signal included in the leakage light L2 is identified.

  For example, when the bending angle θ1a is 20 ° and the fiber to be measured 50 is an R30 fiber, a desired transmittance (for example, −2.0 dB or more) is satisfied, so that bending loss is suppressed and the signal light L1 is reduced. Does not interfere with propagation. Further, it is possible to detect the leaked light L2 having a necessary light amount (for example, −30 dB or more). However, if the fiber to be measured 50 is an R15 fiber having a bending loss smaller than that of the R30 fiber (that is, less leakage), the required amount of leaked light L2 cannot be obtained, and the signal may not be identified. is there.

  That is, that the signal cannot be identified means that the measured fiber 50 is an R15 fiber. Therefore, as shown in FIG. 3B, after moving the first grip portion 12 and changing the bending angle to θ1 = θ1b, the light L2 leaking from the side surface of the measured fiber 50 in this state is measured. The light L2 is incident on one end surface 14a of the optical fiber 14, and the light L2 is detected by the APD 29, and the signal is identified again (third step).

  For example, when the bending angle θ1b is 25 °, the R15 fiber satisfies a desirable transmittance (for example, −2.0 dB or more), so that bending loss is suppressed and propagation of the signal light L1 is not hindered. Further, it is possible to detect the leaked light L2 having a necessary size (for example, −35 dB or more). The R15 fiber can satisfy the transmittance and the light receiving rate even when the bending angle θ1b is 30 °.

  In the above description, the R15 fiber and the R30 fiber are exemplified, but even in the same type of fiber to be measured, the bending loss characteristics often vary due to manufacturing errors or the like. For example, even with the same R15 fiber, the allowable bending radius may vary within a range from 15 mm to about 12 mm, for example. Therefore, even in the same type of fiber to be measured, the bending angle θ1 may be varied according to the intensity of the leaked light L2. That is, regardless of the type of fiber to be measured, the leakage light L2 is first detected at the bending angle θ1a, and when the required light intensity cannot be obtained, the leakage light L2 is detected at the bending angle θ1b (> θ1a). If the required light intensity is not obtained, the bending angle may be further increased.

  In the above description, the desired transmittance is set to -2.0 dB and the desired light receiving rate is set to -35 dB or more. However, as the transmittance and the light receiving rate, desirable values may be appropriately set. Regarding the transmittance, since the measured fiber 50 is an active line, an appropriate value may be set within a range in which communication is not hindered. Further, the light reception rate may be set based on the minimum amount of light that the APD 29 can react with. For example, in the case of an APD that supports 1G transmission, the minimum light receiving sensitivity is approximately -35 dBm. Therefore, when the light intensity of the signal light L1 passing through the measured fiber 50 is 0 dBm, it is desirable that the light receiving rate be −35 dB or more.

  Here, a detailed configuration example of the signal light acquisition structure 10 of the present embodiment will be described. 4 and 5 are plan views showing a specific example of the signal light acquisition structure 10. FIG. 4 shows a state where the measurement fiber 50 is not bent, and FIG. 5 shows a state where the measurement fiber 50 is bent. As shown in these drawings, the signal light acquisition structure 10 includes the bending column 11, the first gripping portion 12 and the second gripping portion 13, the measurement fiber 14, and the ferrule 15. Yes. Further, the signal light acquisition structure 10 further includes a plate-like base member 20 that supports the bending column 11, the first grip portion 12, and the second grip portion 13.

  The bending column 11 is provided to be movable so as to bend the measured fiber 50. In the present embodiment, the bending column 11 is attached to the base member 20 so as to be movable in a direction that intersects the optical axis direction of the measured fiber 50. FIG. 6 is a cross-sectional view of the bending column 11 and the base member 20 along the line VI-VI shown in FIG. As shown in FIG. 6, the base member 20 is formed with an opening 21 penetrating the base member 20 in the thickness direction, and the opening 21 has a fiber 50 to be measured as shown in FIGS. The direction intersecting with the optical axis direction is formed as the longitudinal direction. The bending column 11 has a shaft portion 11 a extending in the thickness direction of the base member 20, and the opening 21 guides the bending column 11 when the shaft portion 11 a is inserted into the opening 21. With such a configuration, the bending column 11 changes the light of the fiber under measurement 50 from a state where the fiber under measurement 50 is not bent (FIG. 4) to a state where the fiber under measurement 50 is bent (FIG. 5). It can be moved in a direction crossing the axial direction.

  Moreover, the 1st holding part 12 has the fiber clamp part 12a, the fixing | fixed part 12b, and the connection member 12c. Similarly, the 2nd holding part 13 has the fiber clamp part 13a, the fixing | fixed part 13b, and the connection member 13c. The fiber clamp portions 12a and 13a are portions for gripping (clamping) the measured fiber 50 at the first gripping position P2 and the second gripping position P3 shown in FIG. The fixing portions 12b and 13b can be rotated around a predetermined axis (for example, an axis perpendicular to the paper surface of FIGS. 4 and 5) intersecting the optical axis direction of the measured fiber 50 and the moving direction of the bending column 11. These are fixed to the base member 20 via support shafts 12d and 13d, respectively. The connecting member 12c connects the fiber clamp portion 12a and the fixed portion 12b to each other while changing the distance between the fiber clamp portion 12a and the fixed portion 12b. Similarly, the connecting member 13c connects the fiber clamp portion 13a and the fixed portion 13b to each other while changing the distance between the fiber clamp portion 13a and the fixed portion 13b in the optical axis direction of the measured fiber 50. In the present embodiment, the connecting members 12c and 13c are made of an elastic member such as a spring, and the above configuration is realized by expanding and contracting in the optical axis direction of the measured fiber 50.

  The signal light acquisition structure 10 adjusts the positions of the fixing portions 12b and 13b along a plane (for example, the plate surface of the base member 20) including the optical axis direction of the measured fiber 50 and the moving direction of the bending column 11. Further, position adjusting mechanisms 22 and 23 are provided. In one example, the position adjustment mechanism 22 includes a plate-like member 22 a slidably fitted in a groove 24 formed in the base member 20, and a bolt 22 b that fixes the member 22 a to the base member 20. ing. The support shaft 12d of the fixed portion 12b is rotatably supported by the member 22a, so that the position of the fixed portion 12b can be adjusted in the longitudinal direction of the groove 24. Similarly, the position adjustment mechanism 23 includes a plate-like member 23 a that is slidably fitted in a groove 25 formed in the base member 20, and a bolt 23 b that fixes the member 23 a to the base member 20. It is configured. The support shaft 13d of the fixed portion 13b is rotatably supported by the member 23a, so that the position of the fixed portion 13b can be adjusted in the longitudinal direction of the groove 25.

  The signal light acquisition structure 10 further includes a fiber holder 26 that holds the measurement fiber 14. The fiber holding unit 26 holds the measurement fiber 14 by holding the ferrule 15, for example. Then, at least one of the bending column 11 and the fiber holding portion 26 is bent in the state in which the bending column 11 is moved so as to bend the measured fiber 50 (see FIG. 5). It is preferable that a mechanism for adjusting the distance from the one end surface 14a is provided. In the present embodiment, the adjustment unit 27 is provided as such a mechanism. The adjustment unit 27 is attached to the base member 20 and supports the fiber holding unit 26 so that the distance between the bending column 11 and the one end surface 14a of the measurement fiber 14 is variable.

  The signal light acquisition structure 10 shown in FIGS. 4 and 5 is operated as follows. First, as shown in FIG. 4, the measured fiber 50 is gripped by the fiber clamp portion 12 a of the first grip portion 12 and the fiber clamp portion 13 a of the second grip portion 13. At this time, the bending column 11 is positioned on one end side (the side away from the measurement fiber 14) of the opening 21, and does not hinder the arrangement of the measured fiber 50. Next, as shown in FIG. 5, the measurement fiber 50 is bent by moving the bending column 11 to the other end side of the opening 21 (the side close to the measurement fiber 14). At this time, the angle in the optical axis direction of the fiber to be measured 50 with respect to the reference line A (see FIG. 1) changes. The change in the angle is caused by the rotation of the fixing portions 12b and 13b around the support shafts 12d and 13d. Absorbed. At this time, the length of the fiber 50 to be measured between the first gripping portion 12 and the second gripping portion 13 also changes, but the change in the length is absorbed by the expansion and contraction of the connecting members 12c and 13c. Is done.

  Thereafter, the light leaked from the side surface of the measured fiber 50 due to the bending of the measured fiber 50 by the bending column 11 is made incident on the one end surface 14 a of the measuring fiber 14. Then, leakage light is detected and a signal included in the leakage light is identified. At this time, if the signal cannot be identified, the position adjusting mechanism 23 moves the first grip portion 12 to increase the bending angle, and light leaking from the side surface of the measured fiber 50 in this state is measured with the measurement fiber 14. Is incident on one end surface 14a of the signal and the signal is identified again.

  The effects obtained by the signal light measurement apparatus 1A having the above configuration, the signal light acquisition structure 10, and the signal light acquisition method will be described. In the present embodiment, as described above, the first grip 12 is movable in the directions B1 and B2 intersecting the direction of the optical axis a1 of the measured fiber 50, and the position of the first grip 12 The bending angle θ1 of the measured fiber 50 can be arbitrarily changed by changing. Therefore, when the bending loss of the measured fiber 50 is relatively large (that is, the amount of leakage light is large), the bending angle θ1 is reduced to suppress an excessive increase in bending loss, and the bending loss of the measured fiber 50 is compared. When the target is small (that is, the amount of leaked light is small), the required leaked light intensity can be obtained by increasing the bending angle θ1. As described above, according to the present embodiment, the influence of the variation in the amount of leakage of the signal light L1 and the bending loss due to the type of the fiber to be measured 50, manufacturing variations, and the like is reduced, and the leakage light L2 having a required size is reduced. It is possible to prevent an excessive increase in optical loss inside the fiber to be measured 50 while acquiring.

  In particular, since the bending characteristics differ greatly between the R15 fiber and the R30 fiber, the preferred bending angle θ1 for obtaining the leaked light L2 is also different from each other. Moreover, it takes time to specify the type of fiber to be measured in advance. Furthermore, if the R30 fiber is bent at an appropriate bending angle for the R15 fiber, communication may be hindered due to a large bending loss. According to the present embodiment, even when R15 fiber and R30 fiber are mixed in the fiber to be measured 50, bending is performed at a bending angle θ1 suitable for each, and the leaked light L2 having a necessary size is provided. Can be easily obtained. Further, since the optical axis of the measurement fiber 14 is inclined toward the optical axis a1 direction side with respect to the direction orthogonal to the reference line A (straight line N in the figure), the measurement fiber 14 is directed to the one end surface 14a. The incidence rate of the leakage light L2 can be increased. Furthermore, by adjusting the bending angle of the fiber 50 to be measured by the first grip portion 12, a suitable bending angle θ1 can be set without deteriorating the incidence rate of the leaked light L2. That is, when the bending angle is adjusted by the second gripping portion 13, the leakage light L2 having a different sign of inclination from the optical axis of the measurement fiber 14 in the leakage light L2 increases, so that the incidence rate is deteriorated. However, if the bending angle of the fiber to be measured 50 is adjusted by the first gripping portion 12, the leaked light L2 having the same sign of the inclination of the optical axis of the measurement fiber 14 increases, so that the incidence rate is increased. Deterioration is suppressed.

  In the signal light acquisition structure 10 of the present embodiment, the one end surface 14 a of the measurement fiber 14 is opposed to the side surface of the measured fiber 50 with a gap G therebetween. In order to increase the optical coupling efficiency between the measuring fiber 14 and the side surface of the measured fiber 50, for example, a method of applying a refractive index matching agent (grease) between the measuring fiber 14 and the measured fiber 50 is also conceivable. However, in order to stably apply and manage the refractive index matching agent at the work site, high skills are required for individual workers. Further, it is necessary to wipe off the refractive index matching agent after measuring the signal light L1, but it is extremely difficult to wipe it off completely. On the other hand, by causing the measurement fiber 14 and the side surface of the measured fiber 50 to face each other across the gap G as in the signal light acquisition structure 10 of the present embodiment, the above-described problem can be avoided. it can. Further, for example, a method in which the measurement fiber 14 is brought into contact with the side surface of the fiber to be measured 50 is conceivable. However, in such a method, the fiber to be measured 50 may be pressed to increase the optical loss. Considering the variation in the outer diameter of the fiber to be measured 50, a method for controlling the position of the one end face 14a of the measurement fiber 14 so as not to press the fiber to be measured 50 is also not realistic. In contrast to these methods, as in the signal light acquisition structure 10 of the present embodiment, the measurement fiber 14 and the side surface of the measured fiber 50 are opposed to each other with a gap G therebetween, thereby reducing the optical loss in the measured fiber 50. The signal light L1 can be suitably acquired while suppressing.

  However, if the gap G is excessively wide, the leaked light L2 is diffused, and the ratio (light receiving rate) of the light incident on the measurement fiber 14 in the leaked light L2 is reduced. Therefore, it is desirable that the width of the gap G is set appropriately. In addition, it is preferable from the Example mentioned later that the space | interval d of the side surface of the to-be-measured fiber 50 and the one end surface 15a of the ferrule 15 is 100 micrometers or less. When the distance d is 100 μm or less, the leakage light L2 having a required size can be obtained without significantly reducing the light receiving rate of the leakage light L2.

  Further, as the measured fiber 50, there are currently an optical fiber having an outer diameter of 0.25 mm and an optical fiber having an outer diameter of 0.5 mm. The outer diameter tolerance of an optical fiber having an outer diameter of 0.25 mm is defined as ± 0.015 mm, and the outer diameter tolerance of an optical fiber having an outer diameter of 0.5 mm is defined as ± 0.025 mm. For these reasons, in order that the measurement fiber 14 does not contact the fiber to be measured 50, the distance d is preferably 50 μm or more.

  Further, as in the present embodiment, the optical axis of the measurement fiber 14 is preferably inclined toward the optical axis a1 direction side of the measured fiber 50 with respect to the direction orthogonal to the reference line A. Thus, by bringing the optical axis direction of the measurement fiber 14 closer to the optical axis a1 direction of the measured fiber 50, the ratio of the light incident on the measuring fiber 14 out of the light L2 leaked from the measured fiber 50 is obtained. Can be increased.

  Moreover, it is preferable that the one end surface 15a of the ferrule 15 facing the side surface of the fiber to be measured 50 is along the reference line A as in the present embodiment. As a result, it is possible to prevent the measured fiber 50 from being pressed by the ferrule 15 and to suppress an increase in optical loss of the measured fiber 50.

  Further, the angle θ2 formed by the direction of the optical axis a2 and the reference line A is preferably larger than 0 °. The portion from the second gripping position P3 to the contact position P1 of the measured fiber 50 may not be a complete straight line depending on the magnitude of the tension applied to the measured fiber 50, and may be bent toward the ferrule 15. . As described above, the angle θ2 is made larger than 0 °, and the portion from the second gripping position P3 to the contact position P1 of the measured fiber 50 is separated from the one end face 15a of the ferrule 15, so that the portion becomes the ferrule 15. Even when the optical fiber is bent, the contact between the measured fiber 50 and the ferrule 15 can be avoided, and an increase in optical loss of the measured fiber 50 can be suppressed.

  Moreover, as shown in FIGS. 4 and 5, the bending column 11 is preferably provided so as to be movable so as to bend the measured fiber 50. As a result, it is possible to apply the bending by moving the bending column 11 after the fiber 50 to be measured is gripped by the first gripping portion 12 and the second gripping portion 13 in a state where the bending is not applied. The operation of installing the fiber 50 can be facilitated.

  Further, the bending strut 11 and the one end surface 14a of the measuring fiber 14 in a state where the bending strut 11 is moved so as to bend the measured fiber 50 to at least one of the bending strut 11 and the fiber holding portion 26. It is preferable that a mechanism for adjusting the interval (for example, the adjustment unit 27) is provided. As a result, the interval between the side surface of the fiber to be measured 50 and the one end surface 14a of the measurement fiber 14 can be adjusted, and the incident efficiency of leaked light into the measurement fiber 14 can be further increased. The spacing between the bending column 11 and the one end surface 14a of the measurement fiber 14 may be adjusted within the movable range of the bending column 11, but the bending column 11 is positioned by contacting the other end of the opening 21. In the above, it is more preferable that the fine adjustment of the position of the fiber holding unit 26 is performed by the adjusting unit 27.

  Moreover, it is preferable that the cross-sectional shape of the contact part with the to-be-measured fiber 50 in the bending support | pillar 11 is a circular arc or an elliptical arc like this embodiment. As a result, it is possible to prevent a sudden increase in bending loss with respect to an increase in the bending angle θ1 of the measured fiber 50 and to easily control the bending loss and the amount of leakage light.

  Here, FIG. 7 is a diagram for explaining an example of the fiber to be measured 50 of the present embodiment, and shows the configuration of the subscriber optical line 40. The subscriber optical line 40 includes an OLT (Optical Line Terminal) 41 installed in the base station, an ONU (Optical Network Unit) 42 installed in the subscriber's house, and a closure 43. The closure 43 includes a housing 43a and a splitter 43b accommodated in the housing 43a. The splitter 43b couples a plurality of optical fibers 45 wired from a plurality of OLTs 41 and an optical fiber 44 wired from one ONU 42 to each other.

  In such a subscriber optical line 40, the OLT 41 sends a signal permitting transmission of an upstream signal to the OLT 41 to a predetermined ONU 42. In contrast, the ONU 42 sends an upstream signal to the OLT 41 within a predetermined time. Thus, in the subscriber optical line 40, bidirectional communication is performed between the OLT 41 and the ONU 42. When grasping the use state of the line transmitted from the ONU 42, it is necessary to identify individual MAC address signals. In a conventional optical capture device used for such signal identification, a signal from the ONU 42 is received via an optical coupler or fiber selector provided in the base station, and a MAC address signal included in the received signal is identified. . Therefore, in the conventional optical capture device, the work place is limited to the base station, and there is a problem that the work cannot be performed on the optical line between the base station and the subscriber's house.

  In response to such a problem, the signal light measurement apparatus 1A of the present embodiment can extract signal light from the side surface of the optical fiber. Therefore, the signal light measurement apparatus 1A is not limited to the inside of the base station. Can be received. For example, in the housing 43a of the closure 43 shown in FIG. 7 (part E in the figure), the signal light is taken out from the optical fiber 45 that connects the ONU 42 and the splitter 43b, and the MAC address included in the signal light is extracted. The signal can be identified. Therefore, it is possible to increase the speed of switching the optical access network and improve the reliability. In addition, it is possible to acquire the leakage light of one of the upstream signal and downstream signal when performing bidirectional communication and reduce the passage loss so as not to interfere with bidirectional communication. Can be analyzed.

(Example)
FIG. 8A is a graph showing an evaluation result regarding the relationship between the distance d between the side surface of the measured fiber 50 and the one end surface 15a of the ferrule 15 and the light receiving rate of the leaked light L2, as an example of the above embodiment. It is. FIG. 8B is a graph showing the relationship between the distance d and the transmittance of the measured fiber 50. 8A and 8B, graphs G11 and G21 show the case where the measured fiber 50 is an R30 fiber, and graphs G12 and G22 show the case where the measured fiber 50 is an R15 fiber. ing. Moreover, the numerical aperture (NA) of the measurement fiber 14 used for the evaluation was 0.22, and the diameter (bending diameter) of the bending column 11 was 8 mm.

  As is clear from FIG. 8A, the light receiving rate is greatly reduced when the distance d exceeds 100 μm. However, if the distance d is 100 μm or less, it can be reduced by several dB. Further, as apparent from FIG. 8B, it can be seen that when the distance d is 50 μm or more, the transmittance is improved as compared with the case where the gap G is not provided (d = 0). For example, in the case of R30 fiber (graph G21), the transmittance is improved by about 0.5 dB. In view of the above, the distance d is preferably 50 μm or more and 100 μm or less.

  The preferred embodiments of the signal light acquisition structure, the signal light measurement device, and the signal light acquisition method according to the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. Changes are possible.

DESCRIPTION OF SYMBOLS 1A ... Signal light measuring device, 10 ... Signal light acquisition structure, 11 ... Bending support | pillar, 12 ... 1st holding part, 13 ... 2nd holding part, 14 ... Measurement fiber, 15 ... Ferrule, 28 ... Condensing lens 29 ... APD, 40 ... subscriber optical line, 43 ... closure, 44,45 ... optical fiber, 50 ... fiber to be measured, A ... reference line, a1, a2 ... optical axis, d ... interval, G ... gap, L1 ... Signal light, L2 ... Leakage light, P1 ... Contact position, P2 ... First grip position, P3 ... Second grip position, [theta] 1 ... Bending angle.

Claims (12)

A signal light acquisition structure for leaking and taking out a part of the signal light from the side surface of the measured fiber that propagates the signal light,
A bend imparting member that imparts a bend to the measured fiber by contacting the measured fiber at a predetermined contact position of the measured fiber;
By gripping the measured fiber at a first gripping position located behind the signal light propagation direction with respect to the contact position, and being movable in a direction intersecting the optical axis direction of the measured fiber A first grip for controlling a bending angle of the fiber to be measured in a bending imparting member;
A second gripping part for gripping the measured fiber at a second gripping position positioned in front of the signal light in the propagation direction of the signal light;
The one end face opposed to the side face of the measured fiber with a gap therebetween, and leaked from the side face of the measured fiber by bending of the measured fiber by the bending imparting member and incident on the one end face A signal light acquisition structure comprising: a measurement fiber that propagates signal light of a part.   An angle θ1 (where θ1> 0 °) is formed with respect to the first optical axis direction of the measured fiber between the first gripping position and the contact position, and the contact from the second gripping position. The optical axis of the measurement fiber is in the first direction with respect to a direction orthogonal to a reference line that forms an angle θ2 (where θ2 ≧ 0 °) with respect to the second optical axis direction of the measured fiber up to the position. The signal light acquisition structure according to claim 1, wherein the signal light acquisition structure is inclined toward the optical axis direction side. A ferrule attached to an end of the one end face side of the measurement fiber;
The signal light acquisition structure according to claim 2, wherein one end surface of the ferrule facing a side surface of the measured fiber is along the reference line.   The signal light acquisition structure according to claim 3, wherein an angle θ2 formed by the second optical axis direction and the reference line is larger than 0 °.   5. The signal light acquisition structure according to claim 3, wherein a distance between a side surface of the measured fiber and the one end surface of the ferrule is 50 μm or more and 100 μm or less.   The signal light acquisition structure according to claim 1, wherein the bending applying member is provided so as to be movable so as to apply bending to the fiber to be measured. A base member for supporting the bending imparting member and the first and second gripping portions;
The first gripping part, or both the first and second gripping parts,
A fiber clamp for gripping the measured fiber;
A fixed portion fixed to the base member so as to be rotatable about a predetermined axis intersecting the optical axis direction of the measured fiber and the moving direction of the bend imparting member;
The signal light acquisition according to claim 6, further comprising: a connecting member that connects the fiber clamp part and the fixing part to each other while making the distance between the fiber clamp part and the fixing part variable. Construction.   The signal light according to claim 7, further comprising a mechanism for adjusting a position of the fixing portion along a plane including an optical axis direction of the measured fiber and a moving direction of the bend imparting member. Acquisition structure. A fiber holding part for holding the measurement fiber;
The bend imparting member and the one end face of the measurement fiber in a state in which the bend imparting member is moved so as to impart bend to the measured fiber to at least one of the bend imparting member and the fiber holding portion. The signal light acquisition structure according to any one of claims 6 to 8, wherein a mechanism for adjusting the interval is provided.   The signal light acquisition structure according to any one of claims 1 to 9, wherein a cross-sectional shape of a contact portion of the bending imparting member with the fiber to be measured is an arc or an elliptical arc. The signal light acquisition structure according to any one of claims 1 to 10,
A signal light measurement apparatus comprising: a light receiving unit that is optically coupled to the other end surface of the measurement fiber and measures the intensity of the part of the signal light that has propagated through the measurement fiber. A signal light acquisition method for leaking and extracting a part of the signal light from a side surface of a measured fiber that propagates signal light,
While gripping the measured fiber at the first and second gripping positions respectively positioned behind and in the propagation direction of the signal light with respect to the predetermined contact position of the measured fiber, the predetermined contact position A first step of imparting a bend to the measured fiber by bringing a bend imparting member into contact with the measured fiber at
The measurement fiber is arranged so that one end surface faces the side surface of the measured fiber with a gap, and the leakage from the side surface of the measured fiber due to the bending of the measured fiber by the bending imparting member. A second step of causing a portion of the signal light to enter the one end surface;
The partial signal leaked from the side surface of the measured fiber after changing the bending angle of the measured fiber by moving the first gripping position in a direction intersecting the optical axis direction of the measured fiber And a third step of allowing light to enter the one end face again.

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