JP5483738B2 - Light incident / exit device and light incident / exit method - Google Patents

Description

  The present invention is used, for example, in an optical core contrast device, optical pulse tester or optical communication device, and service switching technology used for construction and maintenance of a communication network using an optical fiber cable, and receives signal light from the side of the optical fiber. The present invention relates to a light incident / exit device to be emitted and a light incident / exit method.

In the construction and maintenance of a communication network using optical fiber cables, there is a need to identify the core wires in the cable or in the optical fiber at the user's home. This operation is called core contrast.
In the conventional optical fiber contrast work, the optical fiber (optical fiber) that needs to be controlled is bent using a bending device, and the signal emitted from the optical fiber for optical fiber contrast installed on the upper side of the optical fiber. Generally, a method is used in which light is incident on an optical line via an optical coupler, signal light is emitted from the side surface of the bent part of the optical line, and this is detected by a light receiver to identify a target core wire. (Patent Document 1). In addition, by replacing the light source for contrast control with an optical pulse tester, the quality inspection of the optical line and the fault location search are performed via the optical coupler.

  In addition, as a means of communication between workers at different work sites, an optical signal is input from one end of the non-working core in the optical cable, and distortion is applied from outside without cutting the core at the work site. Optical communication is performed by a method of generating an audio signal by replacing a change in characteristics or a loss change due to bending with intensity modulation (see, for example, Patent Documents 2 and 3).

  In any of these operations, it is important to input signal light according to the purpose stably and efficiently into the optical line (optical fiber). For this reason, at present, the signal light incident means is limited to an optical coupler of an outdoor facility that assumes that it is an optical coupler of an in-house facility or a non-working core wire.

  If there is no connector, the core of the optical line may be cut to produce a simple connector or the like on site, and signal light may be input. At present, almost no signal light is input from the optical connector of the outdoor equipment, and the optical coupler of the in-house equipment is used as the only signal light input means.

  In recent years, a communication system in which one optical line is branched into a plurality of lines by an optical branching device has been put into practical use. In this method, the signal light is distributed to all the branch lines by the optical branching device at the input from the optical coupler on the in-house facility side, so that there is a problem that the core line contrast and the optical pulse test cannot be performed. However, a technique for allowing signal light to freely enter from any place on the line equipment side is desired.

  In recent years, a technique relating to an uninterruptible switching method and an uninterruptible switching device that switches an optical line without interrupting signal light while continuing a transmission logical link has been studied (Patent Document 4). However, in the actual line equipment, when the optical line is duplexed and switched to the detour route, it is realized if “two-input, N-output” optical branching units are not installed at both ends of the section of the line (optical fiber). I can't. In view of this, an apparatus for injecting light from the side surface of the optical fiber has been developed at an arbitrary location of the line equipment (see Patent Document 5).

  However, since the above apparatus does not have an optical fiber optimal arrangement mechanism, the coupling efficiency (incidence efficiency) is poor and has not been put into practical use. In addition, this technique has a problem that it cannot be carried out unless a 2-input N-output optical branching device is installed outside the station, and a technique in which an operator can freely input and output signal light from any place of the track facility. Was desired.

  As described above, the light incident device and the light emitting device have been studied as techniques for entering and exiting from the side surface of the optical fiber (Patent Documents 2 and 5). However, these devices have not been widespread due to the low incidence efficiency and emission efficiency, and the narrowness and reliability of the application area are inferior to the incidence / light reception system from the side of the optical fiber. In particular, in the case of a light incident device, since the incident position, incident angle, and spot size are not optimized, the coupling efficiency is greatly reduced, and there is a problem with the size and complexity of equipment required for alignment. It was. Further, in the case of the light emitting device, the fact that only a part of the leaked light is received has a problem that the coupling efficiency is greatly lowered.

Japanese Patent No. 3407812 JP-A-7-38502 JP-A-11-64691 JP 2009-253484 A JP 2009-25210 A

“Optical Wave Engineering”, Corona, P.30-40

As described above, in the conventional light incident / exit technology, the coupling efficiency is greatly increased due to the deviation from the optimal incident position and incident angle, or the difference between the mode field diameter of the optical fiber and the beam diameter of the incident light and the emitted light. There was a problem of being lowered.
The present invention has been made paying attention to the above-mentioned circumstances, and an object thereof is to provide a light incident / exit device and a light incident / exit method capable of efficiently inputting / extracting signal light from the side surface of an optical fiber. There is.

The light incident / exiting device according to the present invention has the following configuration.
(1) a first holding means for bending and holding an arbitrary portion of the first optical fiber with a predetermined radius of curvature; a second holding means for holding the second optical fiber at a predetermined position; The signal light beam emitted from the second optical fiber at a predetermined distance so that the signal light is emitted from the second optical fiber toward the side surface of the first optical fiber at a predetermined angle. An adjusting means for adjusting the diameter to be equal to or smaller than the core diameter of the first optical fiber, and between the side surface of the first optical fiber and the end surface of the second optical fiber, Filling means formed by filling a refractive index matching member having a refractive index equal to the refractive index of the outermost coating of the optical fiber, and the predetermined radius of curvature is sent from the end face of the second optical fiber. The signal light is on the outermost coating side of the first optical fiber. The outermost coating and cladding of the first optical fiber, and the radius of curvature incident on the core of the first optical fiber without total reflection on any surface of the cladding and core of the first optical fiber, The predetermined position is a position where the signal light propagating in a single mode through the linear region of the first optical fiber first reaches the side surface of the outermost coating of the first optical fiber, and the predetermined angle Is the angle at which the signal light that has propagated through the first optical fiber and reached the predetermined position is emitted from the outermost coating of the first optical fiber, and the predetermined distance is the second light The signal light emitted from the core center of the end face of the fiber is set to a distance until it is combined with the core of the first optical fiber.

Further, the predetermined radius of curvature is a radius of curvature ρ in which the incident angles ζ ₃ , ζ ₂ , and ζ ₁ calculated using the equation (1) are smaller than π / 2, and the predetermined position is Direction change angles δ ₁ , δ _2, and δ ₃ calculated using equations (2), (3), (4), and (5) on the side surface of the outermost coating of the first optical fiber. Of the sum (δ ₁ + δ ₂ + δ ₃ ), and the predetermined angle is an incident angle ζ ₃ to the predetermined position calculated using the equation (1), and the predetermined The distance is an aspect in which the signal light emitted from the core center of the end face of the second optical fiber calculated using Expression (6) is incident on the core.

ただし、ρは、前記所定の曲率における曲率中心から前記第一の光ファイバのコア中心までの距離であり、２ｘ_１、２ｘ_２及び２ｘ_３は各々、前記第一の光ファイバのコア、クラッド及び最外被覆の外径であり、ζ_３、ζ_２、ζ_１、ψ_３、ψ_２及びψ_１は各々、前記第一の光ファイバのコアとクラッド、前記第一の光ファイバのクラッドと最外被覆、及び、前記第一の光ファイバの最外被覆の側面での、前記信号光の入射角および屈折角であり、δ_１は前記第一の光ファイバがファイバガイドによって曲がり始めた位置から前記信号光が前記コアと前記クラッドの境界層に到達する位置（Ｃ点）までの前記第一の光ファイバの曲率中心における方向変化角であり、δ_２は当該Ｃ点から前記信号光が前記第一の光ファイバのクラッドと最外被覆の境界面に到達する位置（Ｂ点）までの前記第一の光ファイバの曲率中心における方向変化角であり、δ_３は当該Ｂ点から前記信号光が前記第一の光ファイバの最外被覆の側面に到達する位置（Ａ点）までの前記第一の光ファイバの曲率中心における方向変化角であり、ｎ_１、ｎ_２、ｎ_３及びｎ_４は各々、前記第一の光ファイバのコア、クラッド、最外被覆及び最外被覆と前記第二の光ファイバのコアとの間の媒介物質の屈折率であり、θ_０は前記第一の光ファイバのコアにおける前記信号光のシングルモード伝搬角であり、上記Ａ点の直交座標は（Ａｘ，Ａｙ）、上記Ｂ点の直交座標は（Ｂｘ，Ｂｙ）、上記Ｃ点の直交座標は（Ｃｘ，Ｃｙ）、上記Ｄ点の直交座標は（Ｄｘ，Ｄｙ）であり、符号aは前記第二の光ファイバの端面のコア中心からＡ点までの距離である。

Where ρ is the distance from the center of curvature at the predetermined curvature to the core center of the first optical fiber, and 2x ₁ , 2x ₂ and 2x ₃ are the core, cladding and first of the first optical fiber, respectively. And ζ ₃ , ζ ₂ , ζ ₁ , ψ ₃ , ψ ₂ and ψ ₁ are the core and cladding of the first optical fiber, and the cladding and outermost of the first optical fiber, respectively. The incident angle and the refraction angle of the signal light on the outer coating and the side surface of the outermost coating of the first optical fiber, and δ ₁ from the position where the first optical fiber starts to be bent by the fiber guide The direction change angle at the center of curvature of the first optical fiber to the position (point C) where the signal light reaches the boundary layer between the core and the clad, and δ ₂ is the signal light from the point C First optical fiber cladding and outermost The direction change angle at the center of curvature of the first optical fiber up to a position (point B) reaching the boundary surface of the coating, and δ ₃ is the outermost point of the first optical fiber from the point B. Direction change angle at the center of curvature of the first optical fiber up to the position (point A) reaching the side surface of the coating, and n ₁ , n ₂ , n _3, and n ₄ are each of the first optical fiber The core, the cladding, the outermost coating, and the refractive index of the mediator between the outermost coating and the core of the second optical fiber, and θ ₀ is the single mode of the signal light in the core of the first optical fiber Is the propagation angle, the orthogonal coordinates of the point A are (Ax, Ay), the orthogonal coordinates of the point B are (Bx, By), the orthogonal coordinates of the point C are (Cx, Cy), and the orthogonal coordinates of the point D Is (Dx, Dy), and the symbol a is a code of the end face of the second optical fiber. This is the distance from the center A to point A.

Moreover, the light incident / exit method according to the present invention has the following configuration.
(3) An optical fiber installation procedure in which the first optical fiber is installed in a state where a convex portion is formed by bending an arbitrary portion thereof with a predetermined curvature radius, and the first optical fiber is bent with a predetermined curvature radius in the optical fiber installation procedure. A refractive index matching member contact procedure in which a refractive index matching member having a refractive index equal to the refractive index of the outermost coating of the first optical fiber is closely attached to a predetermined position of the convex portion in the bending of the first optical fiber; In the bent portion of the first optical fiber, the plane including all the centers of the cores of the first optical fiber is installed so that the light beam irradiated from the core center of the second optical fibers in the incident portion is included. A direction of a predetermined angle with respect to the normal direction of the side surface of the outermost coating of the first optical fiber, with the core center of the end face of the second optical fiber at the predetermined position in the refractive index matching member Close to the optical phi Proximity procedure and light incident procedure for causing signal light of a specific wavelength transmitted from the end face of the second optical fiber to enter the core of the first optical fiber from the side surface of the outermost coating of the first optical fiber And the predetermined radius of curvature is such that the signal light transmitted from the end surface of the second optical fiber is the side surface of the outermost coating of the first optical fiber, the outermost surface of the first optical fiber. The radius of curvature that is incident on the core of the first optical fiber without being totally reflected on any of the outer coating and the clad, and the clad and the core of the first optical fiber, and the predetermined position is the first position The signal light that has propagated in a single mode in the straight region of the optical fiber reaches a position where it first reaches the side surface of the outermost coating of the first optical fiber, and the predetermined angle is the first optical fiber Propagating through the predetermined position An angle at which the signal light that has arrived exits into the refractive index matching member from an interface between the outermost coating of the first optical fiber and the refractive index matching member, and the predetermined distance is the second light The signal light emitted from the core center of the end face of the fiber is set to a distance until it is combined with the core of the first optical fiber.

Further, the predetermined radius of curvature is a radius of curvature ρ in which the incident angles ζ ₃ , ζ ₂ , and ζ ₁ calculated using the equation (7) are smaller than π / 2, and the predetermined position is Direction change angles δ ₁ , δ _2, and δ ₃ calculated using the equations (8), (9), (10), and (11) on the side surface of the outermost coating of the first optical fiber. Of the sum (δ ₁ + δ ₂ + δ ₃ ), and the predetermined angle is an incident angle ζ ₃ to the predetermined position calculated using the equation (7), and the predetermined angle The distance is an aspect in which the signal light emitted from the core center of the end face of the second optical fiber calculated using Expression (12) is incident on the core.

ただし、ρは、前記所定の曲率における曲率中心から前記第一の光ファイバのコア中心までの距離であり、２ｘ_１、２ｘ_２及び２ｘ_３は各々、前記第一の光ファイバのコア、クラッド及び最外被覆の外径であり、ζ_３、ζ_２、ζ_１、ψ_３、ψ_２及びψ_１は各々、前記第一の光ファイバのコアとクラッド、前記第一の光ファイバのクラッドと最外被覆、及び、前記第一の光ファイバの最外被覆の側面での、前記信号光の入射角および屈折角であり、δ_１は前記第一の光ファイバがファイバガイドによって曲がり始めた位置から前記信号光が前記コアと前記クラッドの境界層に到達する位置（Ｃ点）までの前記第一の光ファイバの曲率中心における方向変化角であり、δ_２は当該Ｃ点から前記信号光が前記第一の光ファイバのクラッドと最外被覆の境界面に到達する位置（Ｂ点）までの前記第一の光ファイバの曲率中心における方向変化角であり、δ_３は当該Ｂ点から前記信号光が前記第一の光ファイバの最外被覆の側面に到達する位置（Ａ点）までの前記第一の光ファイバの曲率中心における方向変化角であり、ｎ_１、ｎ_２、ｎ_３及びｎ_４は各々、前記第一の光ファイバのコア、クラッド、最外被覆及び最外被覆と前記第二の光ファイバのコアとの間の媒介物質の屈折率であり、θ_０は前記第一の光ファイバのコアにおける前記信号光のシングルモード伝搬角であり、上記Ａ点の直交座標は（Ａｘ，Ａｙ）、上記Ｂ点の直交座標は（Ｂｘ，Ｂｙ）、上記Ｃ点の直交座標は（Ｃｘ，Ｃｙ）、上記Ｄ点の直交座標は（Ｄｘ，Ｄｙ）であり、符号aは前記第二の光ファイバの端面のコア中心からＡ点までの距離である。

Where ρ is the distance from the center of curvature at the predetermined curvature to the core center of the first optical fiber, and 2x ₁ , 2x ₂ and 2x ₃ are the core, cladding and first of the first optical fiber, respectively. And ζ ₃ , ζ ₂ , ζ ₁ , ψ ₃ , ψ ₂ and ψ ₁ are the core and cladding of the first optical fiber, and the cladding and outermost of the first optical fiber, respectively. The incident angle and the refraction angle of the signal light on the outer coating and the side surface of the outermost coating of the first optical fiber, and δ ₁ from the position where the first optical fiber starts to be bent by the fiber guide The direction change angle at the center of curvature of the first optical fiber to the position (point C) where the signal light reaches the boundary layer between the core and the clad, and δ ₂ is the signal light from the point C First optical fiber cladding and outermost The direction change angle at the center of curvature of the first optical fiber up to a position (point B) reaching the boundary surface of the coating, and δ ₃ is the outermost point of the first optical fiber from the point B. Direction change angle at the center of curvature of the first optical fiber up to the position (point A) reaching the side surface of the coating, and n ₁ , n ₂ , n _3, and n ₄ are each of the first optical fiber The core, the cladding, the outermost coating, and the refractive index of the mediator between the outermost coating and the core of the second optical fiber, and θ ₀ is the single mode of the signal light in the core of the first optical fiber Is the propagation angle, the orthogonal coordinates of the point A are (Ax, Ay), the orthogonal coordinates of the point B are (Bx, By), the orthogonal coordinates of the point C are (Cx, Cy), and the orthogonal coordinates of the point D Is (Dx, Dy), and the symbol a is a code of the end face of the second optical fiber. This is the distance from the center A to point A.

( 3 ) In the configuration of ( 2 ), the optical fiber proximity procedure affects the decrease in the incidence rate most after the second optical fiber is roughly abutted with the first optical fiber at the predetermined position and predetermined angle. The fine adjustment of the z-axis in a certain height direction is performed, and then the fine adjustment of the height direction and the x-axis direction, which is the direction of the light beam emitted from the incident optical fiber, is repeated. A procedure for measuring a predetermined position and a predetermined angle, finely moving the y-axis to make fine adjustments in the height direction, and making fine adjustments in the height direction each time fine adjustments are made in the x-axis The procedure of searching for the most efficient predetermined position and predetermined angle using the three-axis stage is automatically executed by controlling the three-axis automatic stage.

( 4 ) In the configuration of ( 2 ), the signal that has passed through the refractive index matching member at the predetermined angle from the second optical fiber to the first optical fiber bent at the predetermined radius of curvature. The light is emitted to the predetermined position at an incident angle ζ3 toward the predetermined position on the side surface of the first optical fiber.

  In the light incident / exiting device according to the present invention, the first optical fiber is bent with a predetermined radius of curvature, and signal light is incident on a predetermined position from a predetermined angle, and the side surface of the first optical fiber and the second optical fiber are incident A refractive index matching member having a refractive index equal to the refractive index of the outermost coating of the first optical fiber is filled between the end face of the optical fiber. The refractive index matching member is preferably a gel-like refractive index matching agent or an elastic plastic or synthetic resin that fills unevenness on the side surface of the first optical fiber with a micrometer order or less without gaps. It is possible to prevent scattering and random diffraction of signal light caused by the surface roughness of the optical fiber.

  The signal light is efficiently transmitted from the refractive index matching member to the outermost coating of the first optical fiber, and then the shortest optical path from the outermost coating to the cladding and from the cladding to the core, and total reflection. And the signal light can be propagated in a single mode to the core of the first optical fiber. Therefore, the signal light can be efficiently incident on the core of the first optical fiber from the side surface of the first optical fiber.

  Further, in the light incident / exiting device according to the present invention, the bent portion of the first optical fiber has a plane including all the centers of the cores of the first optical fiber from the core center of the second optical fiber at the incident portion. It is preferable to hold the first optical fiber and the second optical fiber so that the irradiated light beam is included.

  The light incident / exiting device according to the present invention includes a mechanism for condensing the signal light emitted from the end face of the second optical fiber and suppressing the spread of the beam diameter of the signal light until it enters the core. The incident diameter can be increased, and the beam diameter of the signal light obtained by condensing the signal light emitted from the end face of the second optical fiber is a predetermined distance from the end face of the second optical fiber. It is preferable to be equal to or smaller than the core diameter. For example, the mechanism for condensing signal light emitted from the end face of the second optical fiber is a fused cylindrical lens or spherical lens having a refractive index distribution at the tip of the end face of the second optical fiber. This is a mechanism in which one or a plurality of lenses are installed in the traveling direction of the signal light from the end face of the optical fiber or the second optical fiber.

  The predetermined radius of curvature ρ is such that the signal light transmitted from the end face of the second optical fiber is the side surface of the outermost coating of the first optical fiber, the outermost coating of the first optical fiber, and the cladding. , A radius of curvature that is incident on the core of the first optical fiber without being totally reflected on any surface of the cladding and the core of the first optical fiber, and the predetermined position is the first optical fiber Is the position where the signal light that has propagated in a single mode first reaches the side surface of the outermost coating of the first optical fiber, and the predetermined angle propagates through the first optical fiber. The angle at which the signal light reaching the predetermined position exits from the boundary surface between the outermost coating of the first optical fiber and the refractive index matching member into the refractive index matching member, and a predetermined distance Is the end face of the second optical fiber Wherein the al emitted signal light is the distance to be incident on the core.

  According to the present invention, the signal light emitted from the second optical fiber can be efficiently incident on the core of the first optical fiber from the side surface of the first optical fiber. As a result, it is possible to easily perform the contrast control, the optical pulse test, the optical call, and the service switching at the work site without being relatively restricted by the line equipment.

  As described above, according to the present invention, it is possible to provide a light incident / exit device and a light incident / exit method capable of efficiently entering and exiting signal light from the side surface of an optical fiber.

It is a schematic block diagram which shows the optical communication system which applied the light-incidence method which concerns on this embodiment to uninterrupted switching. It is sectional drawing which shows an example of the light-incidence apparatus used for the uninterruptible switching of the system shown in FIG. It is sectional drawing which expands and shows the convex part by which the strand of the optical line shown in FIG. 1 was bent. It is a schematic block diagram which shows the optical communication system which applied the light-incidence method which concerns on this embodiment to the core line contrast. It is a schematic block diagram which shows the optical communication system which applied the light-incidence method which concerns on this embodiment to the optical pulse test.

Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment.
An example in which the light incident method of the present invention is applied to uninterrupted switching in an optical communication system will be described. FIG. 1 is a schematic configuration diagram illustrating an optical communication system in which the light incident method according to the present embodiment is applied to uninterrupted switching. In FIG. 1, 1 is an in-house device, 2 and 2 'are light blocking filters, 4 is a first optical line (first optical fiber), 5 is an outside device, 6 is an optical input / output port, and 7 is a non-instantaneous device. Light source for switching, 8 is pulsed light, 22 is a non-instantaneous switching device, 9 is a light incident device, 11 is a new optical line (third optical fiber), 12 is a second optical line (second optical fiber) ).

  In the system shown in FIG. 1, the optical coupler 3 is installed at the upper side end of the first optical line 4, and the light incident device 9 is installed at the lower side end. The signal light emitted from the in-house device 1 is incident on the first optical line 4 via the light blocking filter 2 and the optical coupler 3, and the output light is transmitted via the light incident device 9 and the light blocking filter 2 '. It is sent to the external device 5.

  The optical coupler 3 receives the pulsed light transmitted from the uninterruptible switching light source 7 through the input / output port 6 and optically couples it to the signal light to the first optical line 4. Part of the combined signal light is incident on the second optical line 12 via the uninterruptible switching device 22, and the emitted light is sent to the light incident device 9.

Here, the optical path length of the second optical line 12 is set to the first by using the pulsed light 8 emitted from the non-instantaneous switching light source 7 by the uninterruptible switching device 22 (for example, see Patent Document 4). On the basis of the optical path length difference with the optical line 4, the bit code is adjusted to match.
Next, the signal light of the first optical line 4 is blocked using a light blocking means (not shown), and the path of the signal light is changed from the first optical line 4 to the second optical line 12. Subsequently, using the pulsed light 8 emitted from the uninterruptible switching light source 7, the optical path lengths of the second optical line 12 and the newly installed optical line 11 are matched so that the optical path lengths of both coincide with each other. The interruption switching device 22 is controlled, and the non-instantaneous interruption switching device 22 is controlled so that the bit codes of the signal light passing through the second optical line 12 and the new optical line 11 coincide with each other, and an optical interruption means (not shown). Is used to block the signal light of the second optical line 12, and the path of the signal light is transferred from the second optical line 12 to the new optical line 11.

  FIG. 2 is an example of the light incident device 9 used in the above-described instantaneous switching method. In FIG. 2, 4 is a second optical line (first optical fiber), 8 is signal light (pulsed light), 13 is a refractive index matching member, 14 is an incident optical fiber (second optical fiber), 15 Is a radius of curvature at the bent portion of the optical line 4, and 16 is an incident angle of the signal light 8 to the side surface of the optical line 4, that is, a predetermined angle.

FIG. 3 is an enlarged view of a convex portion where the strand of the optical line 4 is bent. In FIG. 3, 4 is an optical line (first optical fiber), 13 is a refractive index matching member, 14 is an incident optical fiber (second optical fiber), 19 is an outermost coating of the optical line 4, and 20 is a light beam. The cladding of the path 4 and 21 indicate the core of the optical line 4. Point A is a boundary point between the refractive index matching member 13 and the outermost coating 19 in the light beam, point B is a boundary point between the outermost coating 19 and the cladding 20 in the light beam, and point C is the cladding 20 and core in the light beam. The boundary point with 21 is shown. x ₁ represents the radius of the core 21. x ₂ represents the radius of the clad 20. x ₃ represents the radius of the outermost coating 19.

In Figure 3, the core 21, cladding 20, shown with each _{2x 1,} 2x 2, 2x ₃ the outer diameter of the outermost coating 19. Also, the radius of curvature 15 of the optical line 4 (distance from the center of curvature of the strand of the optical line 4 to the core center) is ρ, and the incident angles of the signal light 8 at points A, B, and C are respectively ζ ₃ , ζ ₂ and ζ ₁ were set. The refraction angles of the signal light 8 at the points A, B, and C were respectively ψ ₃ , ψ ₂ , and ψ ₁ . In addition, the direction change angles from the point D to the point C, from the point C to the point B, and from the point B to the point A on the optical line 4 are set as δ ₁ , δ ₂ , and δ ₃ , respectively. Further, the single mode propagation angle in the core 21 is θ ₀ , and the refractive indexes of the core 21, the clad 20, the outermost coating 19, and the refractive index matching member 13 are n ₁ , n ₂ , n ₃ , and n ₄ , respectively.

  That is, the light incident device 9 shown in FIG. 2 forms a convex portion as shown in FIG. 3 by holding the optical line 4 in a state bent at a predetermined radius of curvature 15. The portion E until the optical line 4 begins to bend is preferably linear so that the incident signal light 8 is not subjected to multimode conversion or loss.

The light incident device 9 holds the incident optical fiber 14, and the incident optical fiber 14 has a predetermined position on the side surface of the optical line 4 (point A in FIG. 3) from a predetermined angle (ζ ₃ shown in FIG. ₃ ). ) Emits the signal light 8. For example, as a mechanism for holding the optical line 4 bent at a predetermined radius of curvature 15, a V-groove is cut into a cylindrical body so that the bending radius is constant, and the optical line 4 is made to follow the V-groove. There is a mechanism for applying a constant tension from both ends of the bent portion 4. The predetermined angle will be described later.

  In order to prevent misalignment of the optical axes of the optical line 4 and the incident optical fiber 14, the bent portion of the optical line 4 has a plane including all the centers of the cores of the optical line 4 and the incident optical fiber 14 in the incident part. It is preferable to hold the optical line 4 and the incident optical fiber 14 so that a straight line connecting the centers is included.

  Further, it is preferable to fill a refractive index matching member 13 having a refractive index equal to the refractive index of the outermost coating of the optical line 4 between the side surface of the optical line 4 and the end face of the incident optical fiber 14. This is to prevent scattering and random diffraction of the signal light 8 caused by the surface roughness of the optical line 4. The refractive index matching member 13 preferably fills the side surface of the optical line 4 with no gaps on the order of micrometers or less.

  As a mechanism (not shown) for filling the refractive index matching member 13 between the side surface of the optical line 4 and the end surface of the incident optical fiber 14, for example, if the refractive index matching member 13 is a gel, A fence or a groove may be formed so as to surround between the side surface of the optical line 4 and the end surface of the incident optical fiber 14. Or you may make it keep with the surface tension which the refractive index matching member 13 itself has.

The light incident method according to the present embodiment sequentially performs (S1) a light incident device installation procedure, (S2) a refractive index matching member contact procedure, (S3) an optical fiber proximity procedure, and (S4) a light incidence procedure.
(S1) In the light incident device installation procedure, the optical line 4 is installed while being held at a predetermined radius of curvature 15 (ρ shown in FIG. 3).
(S2) In the refractive index matching member contact procedure, the light beam is applied to a predetermined position (point A shown in FIG. 3) of the convex portion in the bending of the optical line 4 bent with a predetermined curvature radius 15 (ρ shown in FIG. 3). A refractive index matching member 13 having a refractive index equal to the refractive index of the outermost coating of the path 4 is brought into close contact. As a result, scattering and random diffraction of the signal light 8 caused by the side surface of the optical line 4, that is, the surface roughness of the outermost coating can be prevented.

(S3) In the optical fiber approach procedure, the end surface of the incident optical fiber 14 is placed on the side surface of the outermost coating of the optical line 4 bent at a predetermined radius of curvature 15 (ρ shown in FIG. 3). It is made to approach at a predetermined angle (ζ ₃ shown in FIG. ₃ ) with respect to the line direction.
Here, a procedure for searching for a predetermined position and a predetermined angle that are experimentally most efficient in the optical fiber approach procedure using the three-axis stage will be described with reference to FIG.

  First, the optical fiber for incidence 14 is roughly abutted at a predetermined position and a predetermined angle, and then, experimentally, fine adjustment of the z-axis in the height direction that most affects the decrease in incidence rate is performed, and then Fine adjustment in the x-axis direction is performed, and a predetermined position and a predetermined angle that are most efficient with the current y-axis value are measured. Thereafter, the procedure for finely adjusting the x-axis while finely moving the y-axis and performing fine adjustment in the height direction is repeated to search for the most efficient predetermined position and predetermined angle. The x-axis is the direction of light emitted from the incident optical fiber.

By experimentally controlling the three-axis automatic stage by computer control, a procedure for searching for the most efficient predetermined position and predetermined angle using the three-axis stage is determined automatically. A predetermined angle can be searched.
(S4) In the light incident procedure, the signal light 8 transmitted from the end face of the incident optical fiber 14 is incident on the core of the optical line 4 from the side surface of the outermost coating of the optical line 4. At this time, the light incident device 9 is configured so that, in the bent portion of the optical line 4, a straight line connecting the centers of the incident optical fibers 14 in the incident part is included in a plane including all the centers of the cores of the optical line 4. 4 and the incident optical fiber 14 are made accessible. In this case, it is preferable that the signal light 8 is stably incident on a predetermined position toward the core of the optical line 4.

In the light incident device 9 according to the present invention, the signal light 8 emitted from the end face of the incident optical fiber 14 is condensed, and the spread of the beam diameter of the signal light 8 until it enters the core is suppressed. The rate can be increased.
However, the beam diameter of the signal light obtained by condensing the signal light 8 emitted from the end face of the incident optical fiber 14 is equal to or smaller than the core diameter of the optical line 4 at a predetermined distance from the end face of the incident optical fiber 14. It is preferable.

  Here, the predetermined distance is a distance until the signal light 8 emitted from the end face of the incident optical fiber 14 enters the core. For example, as a mechanism for suppressing the spread of the beam diameter of the signal light 8 until it enters the core, one or a plurality of cylindrical lenses having a refractive index distribution at the end of the end face of the optical fiber in the incident optical fiber 14 Or a single lens or a plurality of lenses in the direction in which the signal light travels from the end face of the optical fiber fused with the spherical lens or the incident optical fiber.

  In the light incidence device 9 according to the present invention, since the refractive index matching agent member 13 is used, it is necessary to design a lens in the refractive index of the refractive index matching agent member 13. As for the light emission technique, it is preferable to use an optical fiber having a large core diameter and a high numerical aperture for the incident optical fiber 14. As for the light incident technique, it is preferable to use an optical fiber having a small core diameter and a low numerical aperture for the incident optical fiber 14.

  Further, in order to achieve both the efficiency of the light emission technology and the light incidence technology, the core diameter of the incident optical fiber is large, and the beam diameter of the signal light emitted from the incident optical fiber is a predetermined distance and the core diameter of the optical line 4 Is preferably equal to or smaller than. The predetermined distance can be adjusted by moving the incident optical fiber 14 away from the optical line 4 while maintaining a predetermined incident angle and a predetermined position.

In FIG. 3, the state of transmission (refraction) and reflection at the boundary surface of each layer when the signal light 8 is incident from the incident optical fiber 14 on the side surface of the optical line 4 bent at a predetermined radius of curvature ρ. Is shown photometrically.
In FIG. 3, when the path through which the center of the beam from the incident optical fiber 14 passes is observed, the light energy is most concentrated at the center of the beam, and the locus of the light beam is representative at the center of the beam. With respect to the predetermined radius of curvature ρ, the incident angles ζ ₃ , ζ ₂ , and ζ ₁ calculated using the equation (1) need to be smaller than π / 2.

すなわち、所定の曲率半径ρは、入射用光ファイバ１４の端面から送出された信号光８が、屈折率整合部材１３と光線路４の最外被覆１９、光線路４の最外被覆１９とクラッド２０、光線路４のクラッド２０とコア２１のいずれの面においても全反射せずに光線路４のコア２１に入射する曲率半径である。

In other words, the predetermined curvature radius ρ is such that the signal light 8 transmitted from the end face of the incident optical fiber 14 has the refractive index matching member 13 and the outermost coating 19 of the optical line 4, and the outermost coating 19 and the cladding of the optical line 4. 20 is a radius of curvature that is incident on the core 21 of the optical line 4 without being totally reflected on any of the clad 20 and the core 21 of the optical line 4.

The predetermined position A points are the direction change angles δ ₁ , δ _2, and δ ₃ calculated using the equations (2), (3), and (4) on the side surface of the outermost coating 19 of the optical line 4. Of the sum (δ ₁ + δ ₂ + δ ₃ ) on the angle.

また、所定の角度ζ_３は、（１）式を用いて算出される所定の位置Ａ点への入射角ζ_３である。なお、光ファイバ素線の種別（ファイバパラメータ）、曲率半径ρにより、所定の位置Ａ点の方向変化角（δ_１＋δ_２＋δ_３）や入射角ζ_３（＝ψ_３）が異なっていることは言うまでもない。所定の位置Ａ点及び所定の角度ζ_３の原理については後述する。

Further, the predetermined angle ζ ₃ is the incident angle ζ ₃ to the predetermined position A calculated using the equation (1). Note that the direction change angle (δ ₁ + δ ₂ + δ ₃ ) and the incident angle ζ ₃ (= ψ ₃ ) of the predetermined position A are different depending on the type of the optical fiber (fiber parameter) and the radius of curvature ρ. Needless to say. The principle of the predetermined position A point and the predetermined angle ζ ₃ will be described later.

  The light passes through the outermost coating 19 from the closely matched refractive index matching member 13 efficiently, and then has the shortest optical path from the outermost coating 19 to the clad 20 and from the clad 20 to the core 21 without being totally reflected. The signal light 8 from the incident optical fiber 14 can be propagated to the core 21 in a single mode. The predetermined distance is a distance until the signal light 8 transmitted from the incident optical fiber 14 reaches the core of the optical line 4.

  The fact that the light incident from the side surface of the optical line 4 propagates in the core 21 in the single mode means that the light propagating in the single mode is in the core at a certain bent portion in consideration of the reversibility of the light. The paths radiated from 21 to the clad 20, from the clad 20 to the outermost coating 19, and from the outermost coating to the refractive index matching member 13 are exactly the same. Therefore, the basis of the predetermined position, the predetermined angle, and the predetermined distance can be explained by considering the path radiated from the core 21 to the bent portion.

According to the grounds described above with reference to FIG. 3, the signal light 8 reflected in the single-mode (propagation angle θ ₀ ) in the core 21 in the straight region E is the core 21 at the position where the optical line 4 starts to bend. And refracted at the boundary between the clad 20 and the light incident on the point C at an angle φ ₁ . The angle ψ ₁ is smaller than π / 2, and the signal light 8 enters the clad 20 at an angle ζ ₁ . Signal light 8 incident on the clad 20 is incident at an angle [psi ₂ to point B. The angle ψ ₂ is smaller than π / 2, and the signal light enters the outermost coating 19 at an angle ζ ₂ . The signal light 8 incident on the outermost coating 19 enters the point A at an angle ψ ₃ . The angle ψ ₃ is smaller than π / 2, and the signal light 8 enters the refractive index matching member 13 at an angle ζ ₃ .

If the critical angle is exceeded at each boundary surface (C point, B point, A point) of the core 21, the clad 20, the outermost coating 19, and the refractive index matching member 13 due to the bending, a part of the core 21, the clad 20, the outermost coating 19 and the clad 20 The light is transmitted from the clad 20 to the outermost coating 19 and from the outermost coating 19 to the refractive index matching member 13. Eventually, the refraction angle of the radiation path in the refractive index matching member 13 becomes the same as the incident angle ζ ₃ (reference numeral 16 in FIG. 2) at the side incidence. However, since the propagation angle θ ₀ has an allowable angle Δθ corresponding to the numerical aperture, the incident angle ζ ₃ is allowed to vary by Δζ ₃ .

From the above, the predetermined position A point is specified by calculation as the position where the signal light 8 propagated in the single mode in the straight line portion E of the optical line 4 first reaches the side surface of the outermost coating 19 of the optical line 4 by calculation. can do.
Further, the predetermined angle ζ ₃ is calculated as an angle ζ _{3 at} which the signal light 8 that has propagated through the straight line portion E of the optical line 4 and reached the predetermined position A is emitted from the outermost coating 19 of the optical line 4. Can be identified. Note that the predetermined angle ζ ₃ is an angle at which the light propagating through the optical line 4 and reaching the predetermined position A is emitted from the outermost coating 19 of the optical line 4 into the refractive index matching member 13.

Further, the predetermined distance is calculated by calculating the distance that the signal light 8 propagates through the straight line portion E of the optical line 4 and reaches the predetermined position A, thereby calculating the optical line from the core center of the end face of the incident optical fiber 14. It can be specified by adding the distances up to 4. Since the predetermined position A point and the predetermined angle ζ ₃ can be confirmed by experiments, even if an error occurs in gripping the optical line (reference numeral 4 in FIG. 2), the error is experimentally corrected, The signal light 8 can be incident at the most efficient predetermined position and predetermined angle.

  Experimentally, in addition to errors due to gripping of the optical line (reference numeral 4 in FIG. 2), the refraction of the optical line (reference numeral 4 in FIG. 2) due to the tension and temperature applied to the optical line (reference numeral 4 in FIG. 2). Consideration must also be given to changes in the traveling direction of the signal light 8 at the end face due to the change in the rate and the shape deterioration of the end face of the incident optical fiber 14.

  Here, in FIG. 3, the signal light 8 reflected at the point C (stayed in the core 21) is the same as the point C from the boundary point between the next core 21 and the clad 20 in terms of geometrical rays. The light is transmitted at a rate, and finally leaks to the outside of the outermost coating 19 at another position. If the bent part continues, the same behavior will be repeated multiple times. At this time, since refraction occurs at the same ratio of transmittance and reflectance even in the second and subsequent leaks, the absolute transmission amount of the first leaked light is maximized, and the emitted light from the second and subsequent leaks is sequentially reduced. Become.

  In the above, the behavior in which the signal light 8 leaks has been described optically, but the same applies to the incident light. More signal light 8 can be incident on the core by propagating the linear region in a single mode after one reflection and refraction on the surface. Therefore, the first position where the intensity of the leaked light reaches first is optimal as the predetermined position (point A) where the signal light 8 is incident.

Next, with reference to FIG. 2 and FIG.
Here, FIG. 4A shows an optical communication system in which a light incident device 9 is installed on the optical line 4 and a light receiver 10 is installed on the other end of the optical line 4. The light receiver 10 receives the signal light 8 ″ incident from the light incident device 9, and specifies a target core wire depending on whether or not the light is received.

  4B, the light incident device 9 is installed in the optical line 4, the bending part 18 that bends the optical line 4 is provided at the other end of the optical line 4, and the light receiver 10 ′ is installed in the bending part 18. The optical communication system in the case where it did is shown. The light receiver 10 ′ receives the leaked light from the side surface of the optical line 4 in the bent portion 18 of the signal light 8 incident from the light incident device 9, and specifies the target core wire depending on whether or not the light is received.

That is, in the system shown in FIGS. 4A and 4B, first, the light incident device 9 is installed in the optical line (first optical fiber) 4 to be specified. Next, the signal light 8 ″ is incident on the optical line 4 through the light incident device 9.
The signal light is sent out by a light source 7 ″ for controlling the core wire, and 270 Hz to light such as FP-LD (Fabry Perot Laser Diode) or DFB-LD (Distributed Feedback Diode Laser Diode) having a wavelength longer than that of communication light. A signal that is converted into a signal with a certain degree of intensity modulation is used, because the wavelength is different from the communication wavelength, and at the same time, the long-wavelength light is used, so that the bending diameter formed by the light side incident portion 9 is relaxed and communication is performed. The signal light 8 ″ can be efficiently incident on the core of the optical line 4 while minimizing the bending loss with respect to the light. Further, when combined with the light blocking filters 2 and 2 ′, it is possible to contrast the cores even in the in-service state.

  The signal light 8 ″ thus incident is made to have a predetermined bend in the core wire (bending portion 18) in, for example, a closure in the middle of the optical line 4, and the signal light 8 is emitted from the side surface of the optical line 4. Or the signal light 8 is detected by installing the light receiver 10 at a terminal near the user.In the system of FIG. The signal light 8 "incident from 9 is received, and the target core wire is specified by the presence or absence of the light reception. In the system of FIG. 4B, the light receiver 10 ′ receives the leaked light from the side surface of the optical line 4 at the bent portion 18 of the signal light 8 incident from the optical side surface incident portion 9, and receives the light. The target core is identified by the presence or absence of.

  By using the light incident method or the light incident device according to the present embodiment, the signal light 8 ″ is incident from the side surface of the optical line 4, and the signal light 8 is received by the light receiver 10 from one end (terminal) of the optical line 4. It is also possible to make a bend in the middle of the optical line 4 (bending portion 18) and receive the signal light 8 from the side by the light receiver 10 ′.

Next, a procedure for performing an optical pulse test will be described with reference to FIGS.
FIG. 5 is a schematic configuration diagram showing a system in which the light incident method according to the present embodiment is applied to an optical pulse test. Also in the optical pulse test, the light incidence device 9 is first installed in the optical line 4 to be tested, as in the case of the core wire control. Next, the pulse test light 8 ′ is incident on the optical line 4 through the light incident device 9.

  The pulse test light 8 'is sent out by an optical pulse tester 7', and light such as FP-LD or DFB-LD having a wavelength longer than that of communication light is used, as in the case of the core line control. Since the wavelength is different from the communication wavelength and at the same time, the long wavelength light is used, the pulse test light 8 'can be efficiently incident. In-service is also possible by combining the light blocking filters 2 and 2 '. With the pulse test light 8 ′ thus incident, it is possible to perform a test such as an optical fiber failure location search and an equipment failure isolation between the optical line and the user terminal.

  Equipment failure between the optical line equipment and the user terminal due to the peak of the reflection amount indicating the reflection position from the light blocking filter 2 ′ from the OTDR (Optical Time Domain Reflectometer) waveform measured by using the light incidence method according to the present embodiment. Applicable to carving test. Further, by utilizing the fact that the peak of the reflection amount at the open end is different from that of the light blocking filter 2 ′, the presence or absence of the light blocking filter 2 ′ is determined, so that the working optical fiber core wire and the non-working optical fiber The distinction between the cores can be estimated.

By using the light incident method or the light incident device according to the present embodiment, it is possible to confirm the service usage status by monitoring the uplink signal frame transmitted from the external device to the internal device.
The numerical values used in the embodiments of the present invention will be described below. The principle of the predetermined position A point and the predetermined angle ζ ₃ will be described.

Now, the transmittance T _i and the reflectance R _i at the points A, B, and C with respect to the curvature radius ρ can be expressed by the equations (13) and (14) (see, for example, Non-Patent Document 1). . However, consider the case where the electric field surface of the signal light is perpendicular to the incident surface.

また、図３による幾何学的な計算から、ψ_１とψ_ｉは、（１５）式で与えられる。

Also, from the geometric calculation according to FIG. 3, ψ ₁ and ψ _i are given by equation (15).

また、図３による幾何光学的な計算から、δ_１とδ_ｉ（ｉ＝２、３）は曲率半径ρの関数として（１６）式と（１７）式で表される。

Further, from the geometrical optical calculation according to FIG. 3, δ ₁ and δ _i (i = 2, 3) are expressed by equations (16) and (17) as a function of the curvature radius ρ.

また、屈折の法則より、ζ_ｉは、（１８）式で与えられる。

Also, from the law of refraction, ζ _i is given by equation (18).

ただし、添字ｉ（ｉ＝１〜３）はそれぞれＡ点、Ｂ点及びＣ点に対応している。
また、入射用光ファイバ１４から入射する信号光８のコア２１でのシングルモード伝搬角θ_０との関係は、（１９）で与えられる。

However, the suffix i (i = 1 to 3) corresponds to the points A, B and C, respectively.
Further, the relationship between the signal light 8 incident from the incident optical fiber 14 and the single mode propagation angle θ _{0 in} the core 21 is given by (19).

本実施形態では、所定の曲率半径ρで曲げられた光線路４の凸部の所定の位置（Ａ点）に、光線路４の最外被覆１９とほぼ同じ屈折率の屈折率整合部材１３を密着させ、屈折率整合部材１３の中で、光線路４の凸部で光線路４のコアの中心を全て含む平面と入射部において同一高さにコア中心のある入射用光ファイバ１４の端面のコア中心を、所定の位置（Ａ点）における法線方向より所定の角度ζ_３で光線路４の凸部の側面に近接させ、入射用光ファイバ１４の端面から送出した信号光８を光線路４のコア２１に対して入射させる。

In the present embodiment, the refractive index matching member 13 having substantially the same refractive index as that of the outermost coating 19 of the optical line 4 is provided at a predetermined position (point A) of the convex portion of the optical line 4 bent at a predetermined radius of curvature ρ. In the refractive index matching member 13, the end face of the incident optical fiber 14 having the core center at the same height in the incident part and the plane including all the core centers of the optical line 4 at the convex part of the optical line 4. The center of the core is brought closer to the side surface of the convex portion of the optical line 4 at a predetermined angle ζ ₃ from the normal direction at a predetermined position (point A), and the signal light 8 transmitted from the end face of the incident optical fiber 14 is transmitted to the optical line. 4 is incident on the core 21.

With respect to the signal light 8 transmitted from the end face of the incident optical fiber 14, the predetermined curvature radius ρ is set to the core 21 and the clad 20, the clad 20 and the outermost coating 19, and the outermost coating 19 and the refractive index of the optical line 4. The curvature radius ρ that does not totally reflect the signal light 8 at any boundary surface of the matching member 13 is calculated from the equations (13) to (18), and the direction change becomes the predetermined position A of the convex portion of the optical line 4. A position on the angle (δ ₁ + δ ₂ + δ ₃ ), that is, light propagating in a single mode in the linear region of the optical line 4 is transmitted (refracted) in each boundary region of the convex portion of the optical line 4, and the optical line 4 The position at which the outermost coating is first reached is calculated from the equations (16) and (17), the predetermined angle ζ3 is calculated from the equation (1), and finally enters the core 21 from the side surface of the optical line 4. So that the transmitted signal light 8 propagates in a single mode. And [rho, the predetermined position A point of the convex portion of the optical line 4, and a predetermined angle Zeta3, to have a solution in all, determined based on the equation (18) from (13).

The predetermined position is such that the signal light 8 propagated in the single mode in the linear region of the optical line (reference numeral 4 in FIG. 3) has an outer coating 19 and a refractive index at the convex portion of the optical line (reference numeral 4 in FIG. 3). This is the position that first reaches the boundary (point A) with the matching member 13, and the angle from the beginning of the bending of the convex portion of the optical line (reference numeral 4 in FIG. 3), that is, the signal light 8 is refractive index matched from the core 21 It can be obtained as the sum of angles (direction change angles: δ ₁ + δ ₂ + δ ₃ ) between the boundary layers (points A, B, and C) that are reflected and refracted before reaching the member 13.

Further, in order to increase the incidence rate on the outermost coating 19, the refractive index matching member 13 having the same refractive index (n ₄ ≈n ₃ ) as that of the outermost coating 19 is brought into close contact with the boundary surface (point A). The signal light 8 travels almost straight from the refractive index matching member 13 side to the outermost coating 19 (ζ ₃ ≈ψ ₃ ). At this time, if the light incident fiber 14 is inclined by ψ _{3 with} respect to the normal direction of the point A, the signal light 8 transmitted from the incident optical fiber 14 is efficiently incident on the outermost coating 19. At the same time, it propagates through the core 21 in a single mode.

  The predetermined distance is the distance until the signal light 8 transmitted from the incident optical fiber 14 reaches the core of the optical line 4, that is, the distance from the core center of the end face of the incident optical fiber 14 to the point A From the sum of the distance from point A to point B and the distance from point B to point C, the distance from the end face of incident optical fiber 14 to point A, the distance from point A to point B, and the point from point B to point C This is the distance obtained as the sum of the distance and the distance from point C to point D. Now, the orthogonal coordinates of point A are (Ax, Ay), the orthogonal coordinates of point B are (Bx, By), the coordinates of point C are (Cx, Cy), and the orthogonal coordinates of point D are (Dx, Dy) ( 20) to (23).

また、所定の距離fは（２０）式から（２３）式を用いて、（２４）で表すことができる。

Further, the predetermined distance f can be expressed by (24) using the expressions (20) to (23).

ただし、符号aは入射用光ファイバ１４の端面からＡ点までの距離である。
以上の説明から明らかなように、上記実施形態によれば、光線路４の側面からそのコアに、入射用光ファイバ１４から送出された信号光８を効率よく入射させることができる。これによって、作業現場において簡便に、かつ、線路設備に比較的制約されることなく心線対照や光パルス試験及び光通話、サービス切り替えが可能となる。

The symbol a is the distance from the end face of the incident optical fiber 14 to the point A.
As is apparent from the above description, according to the above embodiment, the signal light 8 sent from the incident optical fiber 14 can be efficiently incident on the core from the side surface of the optical line 4. As a result, it is possible to easily perform the contrast control, the optical pulse test, the optical call, and the service switching at the work site without being relatively restricted by the line equipment.

In particular, the present invention can be used for an optical core control or optical pulse test, and an uninterruptible service switching device in the construction and maintenance of an optical fiber cable network.
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some configurations may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different example embodiments may be combined as appropriate.

DESCRIPTION OF SYMBOLS 1 ... In-house device 2, 2 '... Optical cutoff filter 3, 3' ... Optical coupler 4 ... Optical line (1st optical fiber)
5 ... External device 6 ... Light input / output port 7 ... Light source for uninterruptible switching 7 '... Light pulse tester 7 "... Light source for contrast control 8 ... Pulse light from uninterruptible switching light source and internal device Signal light 8 '... Pulse test light from optical pulse tester 8 "... Signal light from light source for contrast control 9 ... Light incident device 10, 10' ... Receiver 11 ... New optical line 12 ... Optical line (No. 1) Second optical fiber)
13 ... Refractive index matching member 14 ... Incident optical fiber (second optical fiber)
15 ... predetermined radius of curvature (ρ)
16: Incident angle (ζ ₃ )
17 ... direction change angle (δ ₁ + δ ₂ + δ ₃ )
DESCRIPTION OF SYMBOLS 18 ... Bending apparatus 19 ... Outermost coating | cover of an optical line (1st optical fiber) 20 ... Cladding of an optical line (1st optical fiber) 21 ... Core of an optical line (1st optical fiber) 22 ... Uninterrupted Switching device

Claims (4)

First holding means for bending and holding an arbitrary portion of the first optical fiber with a predetermined radius of curvature;
Second holding means for holding the second optical fiber in place;
The signal light emitted from the second optical fiber at a predetermined distance so as to emit signal light from the second optical fiber toward the side surface of the first optical fiber at a predetermined angle. Adjusting means for adjusting the beam diameter to be equal to or smaller than the core diameter of the first optical fiber;
Filling formed by filling a refractive index matching member having a refractive index equal to the refractive index of the outermost coating of the first optical fiber between the side surface of the first optical fiber and the end surface of the second optical fiber Means,
The predetermined curvature radius is such that the signal light transmitted from the end surface of the second optical fiber is a side surface of the outermost coating of the first optical fiber, the outermost coating and the cladding of the first optical fiber, A radius of curvature that is incident on the core of the first optical fiber without being totally reflected on any surface of the cladding and the core of the first optical fiber,
The predetermined position is a position where the signal light that has propagated in a single mode through the linear region of the first optical fiber first reaches the side surface of the outermost coating of the first optical fiber;
The predetermined angle is an angle at which the signal light that has propagated through the first optical fiber and reached the predetermined position is emitted from the outermost coating of the first optical fiber,
The predetermined distance is a distance until the signal light emitted from the core center of the end face of the second optical fiber is combined with the core of the first optical fiber ,
The predetermined radius of curvature is a radius of curvature ρ in which the incident angles ζ ₃ , ζ ₂ , and ζ ₁ calculated using the equation (1) are smaller than π / 2.

The predetermined position is the direction change angle δ ₁ calculated using the equations (2), (3), (4), and (5) on the side surface of the outermost coating of the first optical fiber. , Δ ₂ and δ ₃ (δ ₁ + δ ₂ + δ ₃ ) on the angle,

The predetermined angle is an incident angle ζ ₃ to the predetermined position calculated using the equation (1) ,
The predetermined distance is a distance until the signal light emitted from the core center of the end face of the second optical fiber, which is calculated using the equation (6), enters the core.

However,
ρ is the distance from the center of curvature at the predetermined curvature to the core center of the first optical fiber,
2x _1, 2x each ₂ and 2x _3, wherein the first optical fiber having a core, an outer diameter of the cladding and the outermost coating,
ζ ₃ , ζ ₂ , ζ ₁ , ψ ₃ , ψ _2, and ψ ₁ are respectively the core and cladding of the first optical fiber, the cladding and outermost coating of the first optical fiber, and the first An incident angle and a refraction angle of the signal light on the side surface of the outermost coating of the optical fiber;
δ ₁ is at the center of curvature of the first optical fiber from the position at which the first optical fiber begins to bend by the fiber guide to the position (point C) where the signal light reaches the boundary layer between the core and the cladding. Direction change angle,
δ ₂ is a direction change angle at the center of curvature of the first optical fiber from the point C to a position (point B) where the signal light reaches the boundary surface between the cladding and the outermost coating of the first optical fiber. Yes,
δ ₃ is a direction change angle at the center of curvature of the first optical fiber from the point B to a position (point A) where the signal light reaches the side surface of the outermost coating of the first optical fiber,
n ₁ , n ₂ , n _3, and n ₄ are the first optical fiber core, the cladding, the outermost coating, and the refractive index of the mediator between the outermost coating and the second optical fiber core, respectively. And
θ ₀ is the single mode propagation angle of the signal light in the core of the first optical fiber, the orthogonal coordinates of the point A are (Ax, Ay), the orthogonal coordinates of the point B are (Bx, By), The orthogonal coordinates of point C are (Cx, Cy), the orthogonal coordinates of point D are (Dx, Dy), and symbol a is the distance from the core center of the end face of the second optical fiber to point A. A light incident device characterized by the above. An optical fiber installation procedure for installing the first optical fiber in a state where a convex portion is formed by bending an arbitrary portion thereof with a predetermined radius of curvature;
Refraction with a refractive index equal to the refractive index of the outermost coating of the first optical fiber at a predetermined position of the convex portion in the bending of the first optical fiber bent at a predetermined radius of curvature in the optical fiber installation procedure. A refractive index matching member adhesion procedure for closely attaching the index matching member;
The first optical fiber bent portion is installed such that a light beam irradiated from the core center of the second optical fiber in the incident portion is included in a plane including all the core centers of the first optical fiber in the bent portion of the first optical fiber. The core center of the end face of the second optical fiber is located at the predetermined position in the refractive index matching member from a direction at a predetermined angle with respect to the normal direction of the side surface of the outermost coating of the first optical fiber. And an optical fiber approach procedure for approaching to a predetermined distance ;
A light incident procedure for causing signal light of a specific wavelength transmitted from the end face of the second optical fiber to enter the core of the first optical fiber from the side surface of the outermost coating of the first optical fiber. ,
The predetermined curvature radius is such that the signal light transmitted from the end surface of the second optical fiber is a side surface of the outermost coating of the first optical fiber, the outermost coating and the cladding of the first optical fiber, A radius of curvature that is incident on the core of the first optical fiber without being totally reflected on any surface of the cladding and the core of the first optical fiber,
The predetermined position is a position where the signal light propagating in a single mode through the linear region of the first optical fiber first reaches the side surface of the outermost coating of the first optical fiber;
The predetermined angle propagates through the first optical fiber, and the signal light that reaches the predetermined position is refracted from the boundary surface between the outermost coating of the first optical fiber and the refractive index matching member. The angle of exit into the rate matching member,
The predetermined distance is a distance until the signal light emitted from the core center of the end face of the second optical fiber is combined with the core of the first optical fiber ,
The predetermined radius of curvature is a radius of curvature ρ in which the incident angles ζ ₃ , ζ ₂ , and ζ ₁ calculated using the equation (7) are smaller than π / 2.

The predetermined position is the direction change angle δ ₁ calculated using the equations (8), (9), (10), and (11) on the side surface of the outermost coating of the first optical fiber. , Δ ₂ and δ ₃ (δ ₁ + δ ₂ + δ ₃ ) on the angle,

The predetermined angle is an incident angle ζ ₃ to the predetermined position calculated using the equation (7) ,
The predetermined distance is a distance until the signal light emitted from the core center of the end face of the second optical fiber, which is calculated using the equation (12), enters the core.

However,
ρ is the distance from the center of curvature at the predetermined curvature to the core center of the first optical fiber,
2x _1, 2x each ₂ and 2x _3, wherein the first optical fiber having a core, an outer diameter of the cladding and the outermost coating,
ζ ₃ , ζ ₂ , ζ ₁ , ψ ₃ , ψ _2, and ψ ₁ are respectively the core and cladding of the first optical fiber, the cladding and outermost coating of the first optical fiber, and the first An incident angle and a refraction angle of the signal light on the side surface of the outermost coating of the optical fiber;
δ ₁ is at the center of curvature of the first optical fiber from the position at which the first optical fiber begins to bend by the fiber guide to the position (point C) where the signal light reaches the boundary layer between the core and the cladding. Direction change angle,
δ ₂ is a direction change angle at the center of curvature of the first optical fiber from the point C to a position (point B) where the signal light reaches the boundary surface between the cladding and the outermost coating of the first optical fiber. Yes,
δ ₃ is a direction change angle at the center of curvature of the first optical fiber from the point B to a position (point A) where the signal light reaches the side surface of the outermost coating of the first optical fiber,
n ₁ , n ₂ , n _3, and n ₄ are the first optical fiber core, the cladding, the outermost coating, and the refractive index of the mediator between the outermost coating and the second optical fiber core, respectively. And
θ ₀ is the single mode propagation angle of the signal light in the core of the first optical fiber, the orthogonal coordinates of the point A are (Ax, Ay), the orthogonal coordinates of the point B are (Bx, By), The orthogonal coordinates of point C are (Cx, Cy), the orthogonal coordinates of point D are (Dx, Dy), and symbol a is the distance from the core center of the end face of the second optical fiber to point A. A light incident method characterized by the above. The optical fiber proximity procedure includes:
After roughly matching the second optical fiber to the first optical fiber at the predetermined position and predetermined angle, fine adjustment of the z-axis in the height direction that most affects the decrease in incidence rate is performed, and then Repeated fine adjustment of the height direction and the x-axis direction, which is the direction of the light beam emitted from the incident optical fiber,
The y-axis value is measured at the most efficient predetermined position and angle, and then the y-axis is finely moved to make fine adjustments in the height direction. Repeat the procedure of fine adjustment of direction,
3. The light according to claim 2 , wherein the step of searching for the most efficient predetermined position and predetermined angle using the three-axis stage is automatically executed by controlling the three-axis automatic stage. Incident method. The signal light that has passed through the refractive index matching member from the second optical fiber at the predetermined angle to the first optical fiber bent at the predetermined radius of curvature is a side surface of the first optical fiber. _3. The light incident method according to claim 2 , wherein the signal light is emitted to the predetermined position at an incident angle ζ ₃ toward the predetermined position.

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