JP2013113890A - Optical fiber coupling device and optical fiber coupling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber coupling technique that efficiently bringing signal light to incidence from a side face of an optical fiber.SOLUTION: A light incidence device 9 has a mechanism that emits signal light at a prescribed angle from an incidence-purpose optical fiber 14 to a communication-purpose optical fiber 4A curved at a prescribed radius of curvature toward a prescribed position on a side face of a first optical fiber 4A and self-forms an optical waveguide using photo-curable resin 13 to restrain the beam diameter expansion of the signal light emitted from the incidence-purpose optical fiber 14 in a position where the signal light couples with a core 21 of the communication-purpose optical fiber 4A. In this way, the signal light can be efficiently brought to incidence from the side face of the communication-purpose optical fiber 4A on the core 21 of that optical fiber 4A.

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 an optical fiber coupling device and an optical fiber coupling method.

In the construction and maintenance of a communication network using optical fiber cables, there is a need to identify the core wire in the cable or the optical fiber at the user's house at the work site. This operation is called cord contrast.
In a conventional core wire contrast operation, generally, a bending device is used to bend an optical line (optical fiber) that requires contrast. In this state, the signal light emitted from the light source for controlling the optical fiber installed on the upper side of the optical line is incident on the optical line through the optical coupler, and the signal light is emitted from the side surface of the bent portion of the optical line. A method is used in which this is detected by a light receiver to identify a target core wire (Non-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.

  By the way, in recent years, in the optical access network, “non-instantaneous switching technology” for switching the signal light to the detour route in a state where communication is continued has been studied. The problem here is that in a real line facility, when duplexing a communication line and switching to a detour route, there is no “two-input, N-output” optical branching device installed at both ends of the section of the line (optical fiber). It cannot be realized. In view of this, an apparatus for injecting light from the side surface of an optical fiber has been developed at an arbitrary location of a line facility.

  However, the conventional technology does not include a mechanism for arranging and holding the communication optical fiber and the incident optical fiber at the optimum positions. For this reason, it has been extremely difficult to obtain sufficient coupling efficiency (incidence efficiency). In particular, when light is incident from the side of the optical fiber, incident light and outgoing light are diffused in the coupling with the core of the optical fiber, so that there is a problem that the coupling efficiency is greatly reduced, leading to practical use. It wasn't.

“Examination of a core contrast device that can determine the upper and lower part of an optical line”, 2003 IEICE Communication Society Conference, B-10-10

As described above, in the conventional light incident / exit technology, there is a problem that the coupling efficiency is greatly reduced due to the diffusion of incident light and outgoing light before being coupled to the core of the optical fiber.
The present invention has been made paying attention to the above-described circumstances, and an object of the present invention is to provide a local signal optical fiber coupling device and a local signal optical fiber coupling that can efficiently input and output signal light from the side surface of the optical fiber. It is to provide a method.
There has been a problem that the coupling efficiency is greatly reduced due to a deviation from the optimum incident position and angle, or a difference between the mode field diameter of the optical fiber and the beam diameter of the incident light and outgoing light.

  The present invention has been made paying attention to the above-described circumstances, and an object thereof is to provide an optical fiber coupling device and an optical fiber coupling method capable of efficiently entering and exiting signal light from the side surface of the optical fiber. There is.

The optical fiber coupling 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; Adjusting means for emitting signal light from the second optical fiber at a predetermined angle toward the side surface of the first optical fiber, and the predetermined radius of curvature of the second optical fiber The signal light transmitted from the end surface is a side surface of the outermost coating of the first optical fiber, the outermost coating and cladding of the first optical fiber, or any of the cladding and core surfaces of the first optical fiber. The predetermined radius is a radius of curvature that is incident on the core of the first optical fiber without being totally reflected, and the predetermined position is that the signal light that has propagated in a single mode in the linear region of the first optical fiber is the first radius. On the side of the outermost coating of one optical fiber. The predetermined angle is light that propagates through the first optical fiber and is an angle at which the signal light that reaches the predetermined position is emitted from the outermost coating of the first optical fiber. A fiber coupling device, which is cured by irradiation with light of a specific wavelength between a side surface of the first optical fiber and an end surface of the second optical fiber, and is outermost of the first optical fiber after curing. Filling means formed by filling a photocurable resin having a refractive index equal to the refractive index of the coating, and propagating light from a light source having a specific wavelength for curing the photocurable resin to the second optical fiber, The light-curing resin is irradiated with light from the light source having the specific wavelength, and the photo-curing resin is cured to form a self-forming optical waveguide unit that self-forms the optical waveguide.

  (2) In the configuration of (1), the self-forming optical waveguide means propagates light to the first optical fiber, and leaks light from a bent portion of the first optical fiber to the second optical fiber. A light intensity measuring means for measuring the light intensity received at the light intensity change amount measured by the light intensity measuring means after the start of incidence of light from the light source, the first optical fiber and the second optical fiber; Judging means for judging that the formation of the waveguide is completed by reaching a predetermined amount of change in light intensity corresponding to the loss of the light emitting device that decreases with the formation of the optical waveguide between the optical fibers; It is set as the aspect provided.

Moreover, the optical fiber coupling 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. An optical fiber holding procedure for holding the second optical fiber at a predetermined position of the convex portion in the bending of the first optical fiber, and a core of the first optical fiber in the bending portion of the first optical fiber. The core center of the end face of the second optical fiber installed so that the light beam irradiated from the core center of the second optical fiber in the incident portion is included in the plane including all the centers is located at the predetermined position. An optical fiber approach procedure for approaching from a direction at a predetermined angle with respect to the normal direction of the side surface of the outermost coating of one optical fiber, and signal light of a specific wavelength transmitted from the end face of the second optical fiber. The first A light incident procedure for entering the core of the first optical fiber from the side surface of the outermost coating of the optical fiber, and the predetermined radius of curvature is the signal light transmitted from the end surface of the second optical fiber. The outermost coating side surface of the first optical fiber, the outermost coating and cladding of the first optical fiber, and the first optical fiber cladding and core without total reflection on any of the surfaces of the first optical fiber cladding and cladding. The radius of curvature is incident on the core of one optical fiber, and the predetermined position is the outermost coating of the first optical fiber on which the signal light that has propagated in a single mode through the linear region of the first optical fiber. And the predetermined angle propagates through the first optical fiber, and the signal light reaching the predetermined position is the boundary of the outermost coating of the first optical fiber. The angle of exit from the surface A fiber coupling method, wherein the first optical fiber bent at a predetermined curvature radius in the optical fiber installation procedure is cured by irradiation with light of a specific wavelength at the predetermined position of the convex portion in the bending. A photocurable resin adhesion procedure for making a photocurable resin having a refractive index equal to the refractive index of the outermost coating of the first optical fiber, and a light source of a specific wavelength for curing the photocurable resin. A self-forming optical waveguide procedure for propagating light through the second optical fiber, irradiating the photocurable resin with light of a light source of the specific wavelength, curing the photocurable resin, and self-forming an optical waveguide; It is set as the aspect to comprise.

  (4) In the configuration of (3), the self-forming optical waveguide procedure propagates light to the first optical fiber, and leaks light from a bent portion of the first optical fiber to the second optical fiber. The intensity of the light received by the light source is measured, and the amount of change in the light intensity measured after the start of light incidence from the light source is accompanied by the formation of the optical waveguide between the first optical fiber and the second optical fiber. In this aspect, it is determined that the formation of the waveguide is completed when a predetermined amount of change in light intensity corresponding to the loss of the light emitting device that decreases is reached.

  In the optical fiber coupling device according to the present invention, the first optical fiber is bent with a predetermined radius of curvature, 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. It hardens | cures by irradiation of the light of a specific wavelength between the end surfaces of an optical fiber, and is filled with the photocurable resin which is a refractive index equal to the refractive index of outermost coating of said 1st optical fiber after hardening. The photo-curing resin fills unevenness of micrometer order or less on the side surface of the first optical fiber without gaps, and thereby the signal light caused by the surface roughness of the side surface of the first optical fiber, that is, the outermost coating. Scattering and random diffraction can be prevented.

  Efficiently transmits the signal light from the light-curing resin that adheres 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.

  In the photocurable resin, a portion irradiated with light is cured and the refractive index thereof is increased, so that the cured portion (resin core portion) constitutes a waveguide (structure) having a light confinement function. Since this waveguide is continuously formed during light irradiation and grows in the longitudinal direction, it is possible to prevent diffusion of incident light from the second optical fiber, and the bent portion of the first optical fiber. It is possible to prevent diffusion of leaked light from

  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 an optical fiber coupling device and an optical fiber coupling method that can efficiently input and output signal light from the side surface of the optical fiber.

It is a schematic block diagram which shows the optical communication system which applied the optical fiber coupling method which concerns on this embodiment to uninterrupted switching. It is sectional drawing which shows an example of the optical fiber coupling 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 fiber shown in FIG. 1 was bent. It is a schematic block diagram which shows the optical communication system which applied the optical fiber coupling 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 optical fiber coupling 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 optical fiber coupling method according to the present embodiment is applied to uninterrupted switching. In FIG. 1, 1 is an in-house device, 2A and 2B are optical blocking filters, 3 is an optical coupler, 4A is a first optical line (first optical fiber), and 4B is a second optical line (second optical fiber). ) 4C is a new optical line (third optical fiber), 5 is an external device, 6 is an optical input / output port, 7 is a light source for uninterruptible switching, 8 is an uninterruptible switching device, and 9 is light incident / exit 1 shows a device (optical fiber coupling device).

  In the system shown in FIG. 1, the optical coupler 3 is installed at the upper side end of the first optical line 4A, 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 4A via the light blocking filter 2A and the optical coupler 3, and the output light is transmitted outside via the light incident device 9 and the light blocking filter 2B. Sent to the device 5.

  The optical coupler 3 receives the pulsed light L1 sent from the uninterruptible switching light source 7 via the input / output port 6, and the pulsed light L1 is converted into signal light sent to the first optical line 4A. Join. A part of the signal light combined with the pulsed light L1 is incident on the second optical line 4B via the uninterruptible switching device 8, and the emitted light is sent to the light incident device 9.

  Here, in the uninterruptible switching device 8, although not shown in detail, first, the optical path length of the second optical line 4 </ b> B is set using the pulsed light L <b> 1 emitted from the uninterruptible switching light source 7. On the basis of the optical path length difference with the optical line 4A, the bit code is adjusted to match. Next, the signal light of the first optical line 4A is blocked using a light blocking mechanism (not shown), and the path of the signal light is changed from the first optical line 4A to the second optical line 4B. Subsequently, control is performed using the pulsed light L1 emitted from the uninterruptible switching light source 7 so that the optical path lengths of both coincide with each other based on the optical path length difference between the second optical path 4B and the new optical path 4C. Then, control is performed so that the bit codes of the signal light passing through the second optical line 4B and the new optical line 4C match, and the signal light of the second optical line 4B is transmitted using a light blocking mechanism (not shown). The signal light path is switched from the second optical line 4B to the new optical line 4C.

FIG. 2 is an example of the light incident device 9 used in the non-instantaneous switching method. In FIG. 2, 4B is a second optical line (first optical fiber), L2 is signal light (including pulsed light L1), 13 is a photocurable resin (refractive index matching member), and 14 is an incident optical fiber. (Extension of the second optical line 4B), ρ is a radius of curvature at the bent portion of the optical line 4A, and ζ ₃ is an incident angle of the signal light L2 to the side surface of the optical line 4A, that is, a predetermined angle.

FIG. 3 is an enlarged view of a convex portion where the strand of the optical line 4A is bent. In FIG. 3, 4A is an optical line (first optical fiber), 13 is a photocurable resin, 14 is an incident optical fiber (extension of the second optical line), 19 is an outermost coating of the optical line 4A, 20 Indicates the cladding of the optical line 4A, and 21 indicates the core of the optical line 4A. Point A is a boundary point between the photocurable resin 13 and the outermost coating 19 in the light beam emitted from the input / output optical fiber 14, and point B is a boundary point between the outermost coating 19 and the cladding 20 in the light beam. , C indicates a boundary point between the clad 20 and the core 21 in the light beam. 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. Further, the radius of curvature of the optical line 4A (distance from the center of curvature of the strand of the optical line 4A to the core center) is ρ, and the incident angles of the signal light L2 at the points A, B, and C are ζ ₃ and ζ, respectively. ₂ and ζ ₁ were set. The refraction angles of the signal light L2 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 in the optical line 4A are set as δ ₁ , δ ₂ , and δ ₃ , respectively. In addition, 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 photocurable resin 13 are n ₁ , n ₂ , n ₃ , and n ₄ , respectively.

  That is, the light incidence device 9 shown in FIG. 2 forms a convex portion as shown in FIG. 3 by holding the optical line 4A in a state bent at a predetermined radius of curvature ρ. The portion E until the optical line 4A begins to be bent is preferably linear so that the incident signal light L2 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 4A (point A in FIG. 3) from a predetermined angle (ζ ₃ shown in FIG. ₃ ). ) To emit the signal light L2. For example, as a mechanism for holding the optical line 4A bent at a predetermined radius of curvature ρ, a cylindrical body is engraved with a V-groove so that the bending radius is constant, and the optical line 4A is aligned along the V-groove. There is a mechanism for applying a constant tension from both ends of the bent portion of 4A. The predetermined angle will be described later.

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

  Further, the resin is cured by irradiation with light of a specific wavelength between the side surface of the optical line 4A and the end surface of the incident optical fiber 14, and has a refractive index equal to the refractive index of the outermost coating of the first optical fiber after curing. It is preferable to fill the photocurable resin 13. This is to prevent scattering and random diffraction of the signal light L2 caused by the surface roughness of the optical line 4A. The cured photocurable resin 13 preferably fills the concaves and convexes on the side surface of the optical line 4A on the order of micrometers or less without any gaps.

  As a mechanism (not shown) for filling the photocurable resin 13 between the side surface of the optical line 4A and the end surface of the incident optical fiber 14, for example, if the photocurable resin 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 photocurable resin 13 itself has.

The light incident method according to this embodiment includes (S1) a light incident device installation procedure, (S2) a photocurable resin adhesion procedure, (S3) an optical fiber proximity procedure, (S4) a self-forming optical waveguide procedure, and (S5) light. The incident procedure is performed in order.
(S1) In the light incident device installation procedure, the optical line 4A is installed while being held at a predetermined radius of curvature (ρ shown in FIG. 3).
(S2) In the refractive index matching member contact procedure, the optical line is placed at a predetermined position (point A shown in FIG. 3) of the convex portion in the bending of the optical line 4A bent at a predetermined radius of curvature (ρ shown in FIG. 3). The refractive index matching member 13 having a refractive index equal to the refractive index of the outermost coating 4 is adhered. As a result, scattering and random diffraction of the signal light L2 caused by the side surface of the optical line 4A, that is, the surface roughness of the outermost coating can be prevented.
(S3) In the optical fiber proximity procedure, the end surface of the incident optical fiber 14 is placed on the side surface of the outermost coating of the optical line 4A bent at a predetermined radius of curvature (ρ shown in FIG. 3), and the normal of the point A It is made to approach at a predetermined angle (ζ ₃ shown in FIG. ₃ ) with respect to the 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 (S3) 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 moving the y-axis and finely adjusting the x-axis while 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 14.

The procedure for searching for the most efficient predetermined position and predetermined angle using the three-axis stage experimentally is controlled automatically by controlling the three-axis automatic stage by computer control. And a predetermined angle can be searched.
(S4) In the self-forming optical waveguide procedure, the light of the specific wavelength light source for curing the photocurable resin 13 is propagated to the incident optical fiber 14, and the light source of the specific wavelength is transmitted from the end surface of the incident optical fiber 14. Light is applied to the photocurable resin 13 to cure the photocurable resin 13 and to self-form the optical waveguide. At this time, in the photocurable resin 13, the portion irradiated with light is cured and the refractive index thereof is increased. Therefore, the cured portion (resin core portion) constitutes a waveguide (structure) having a light confinement function. To do. Since this waveguide is continuously formed during light irradiation and grows in the longitudinal direction, it is possible to prevent the diffusion of incident light from the incident optical fiber 14, and from the bent portion of the first optical line 4A. It becomes possible to prevent diffusion of leaked light.

  (S5) In the light incident procedure, the signal light L2 transmitted from the end face of the incident optical fiber 14 is incident on the core 21 of the optical line 4A from the side surface of the outermost coating 19 of the optical line 4A. At this time, the light incident device 9 includes the light beam so that the plane that includes all the centers of the cores 21 of the optical line 4A includes a straight line that connects the centers of the incident optical fibers 14 in the incident part. The path 4A and the incident optical fiber 14 are made accessible. In this case, it is preferable that the signal light L2 is stably incident on a predetermined position toward the core 21 of the optical line 4A.

  In the light incident device 9 according to the present embodiment, the beam diameter is expanded from the end face of the incident optical fiber 14 to the optical line until the signal light L2 emitted from the end face of the incident optical fiber 14 enters the core 21. By suppressing the space up to 4A by forming the optical waveguide with the photocurable resin 13, the incidence rate can be increased. 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.

In order to achieve both efficiency of the light emitting technique and the light incident technique, the core diameter of the incident optical fiber 14 is large, and the beam diameter of the signal light L2 emitted from the incident optical fiber 14 is an optical line at a predetermined distance. It is preferably equal to or smaller than the core diameter of 4A.
In the self-forming optical waveguide procedure S4, light is propagated to the first optical line 4A, and the light intensity received from the bent portion of the first optical line 4A is received by the second optical line 4B. The amount of change in light intensity measured by the optical power meter and measured by the optical power meter after the start of the incidence of light from the light source 7 is between the first optical line 4A and the second optical line 4B. It is preferable to determine whether or not the formation of the waveguide is completed based on whether or not a predetermined amount of change in light intensity corresponding to the loss of the light incidence device 9 that decreases with the formation has been reached. The amount of change in the predetermined light intensity is a difference between the coupling efficiency after the self-formed waveguide is cured and the coupling efficiency before the self-formed waveguide is cured.

In FIG. 3, the state of transmission (refraction) and reflection at the boundary surface of each layer when the signal light L2 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Ｌ２が、光硬化性樹脂１３と光線路４Ａ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４Ａ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４Ａのコア２１に入射する曲率半径である。

That is, the predetermined curvature radius ρ is such that the signal light L2 sent from the end face of the incident optical fiber 14 is light-curing resin 13 and the outermost coating 19 of the optical line 4A, and the outermost coating 19 and the cladding of the optical line 4. 20, a radius of curvature that is incident on the core 21 of the optical line 4A without being totally reflected on any of the clad 20 and the core 21 of the optical line 4A.

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.

  It efficiently transmits to the outermost coating 19 from the photocurable resin 13 that is in close contact, and then has the shortest optical path from the outermost coating 19 to the cladding 20 and from the cladding 20 to the core 21 and without total reflection. The signal light 8 from the incident optical fiber 14 can be propagated to the core 21 in a single mode.

  The fact that the light incident from the side surface of the optical line 4A 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 light. The path radiated from 21 to the clad 20, from the clad 20 to the outermost coating 19, and from the outermost coating to the photocurable resin 13 is 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 L2 reflected in the single-mode (propagation angle θ ₀ ) inside the core 21 in the straight region E is the core 21 at the position where the optical line 4A starts to bend. And refracted at the boundary between the clad 20 and the light incident on the point C at an angle ψ ₁ . The angle ψ ₁ is smaller than π / 2, and the signal light L2 enters the clad 20 at an angle ζ ₁ . Signal light L2 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 L ₂ enters the outermost coating 19 at an angle ζ ₂ . Signal light L2 incident to the outermost coating 19 is incident at an angle [psi ₃ to point A. Angle [psi ₃ is smaller than [pi / 2, the signal light L2 is incident at an angle zeta ₃ to the light curable resin 13 is the refractive index matching member.

When 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 photocurable resin 13 due to the bending, a part of the core 21, the clad 20, the clad 20, The light is transmitted from the clad 20 to the outermost coating 19 and from the outermost coating 19 to the photocurable resin 13. Eventually, the refraction angle of the radiation optical path in the photocurable resin 13 becomes the same as the incident angle ζ ₃ (see 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 L2 propagating in the straight portion E of the optical line 4A in the single mode first reaches the side surface of the outermost coating 19 of the optical line 4A. can do. Further, the predetermined angle ζ ₃ is calculated as the angle ζ _{3 at} which the signal light L2 that propagates through the straight line portion E of the optical line 4A and reaches the predetermined position A is emitted from the outermost coating 19 of the optical line 4A. Can be identified. The predetermined angle ζ ₃ is an angle at which the light that has propagated through the optical line 4A and reached the predetermined position A is emitted from the outermost coating 19 of the optical line 4A into the photocurable resin 13.
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 4A 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 L2 leaks has been described optically, but the same applies to the incident light. More signal light L2 can be incident on the core 21 by propagating the linear region in a single mode after one reflection and refraction on the surface. Accordingly, the first position where the intensity of the leakage light reaches first is optimal as the predetermined position (point A) where the signal light L2 is incident.

Next, with reference to FIG. 2 and FIG.
Here, FIG. 4A shows an optical communication system in which the light incident device 9 is installed on the optical line 4A and the light receiver 10 is installed on the other end of the optical line 4A. The light receiver 10 receives the signal light L3 incident from the light incident device 9, and specifies a target core wire depending on whether or not the light is received.

  In FIG. 4B, the light incident device 9 is installed in the optical line 4, the bent part 18 that bends the optical line 4 A is provided at the other end of the optical line 4 A, and the light receiver 10 ′ is installed in the bent 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 </ b> A at the bending portion 18 of the signal light L <b> 3 incident from the light incident device 9, and specifies a 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) 4A to be specified. Next, the signal light L <b> 3 enters the optical line 4 through the light incident device 9.
The signal light is transmitted from the light source 7B for controlling the core wire, and is about 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 the communication light. The signal is used after adding intensity modulation. Since long-wavelength light is used at the same time as the wavelength different from the communication wavelength, the signal light L3 is emitted while reducing the bending diameter created by the light incident device 9 and minimizing bending loss with respect to the communication light. It can efficiently enter the core of the path 4A. Further, when combined with the light blocking filters 2A and 2B, it is possible to contrast the cores even in the in-service state.

  For example, the signal light L3 incident in this way is bent in the core wire (bending portion 18) in a closure in the middle of the optical line 4A, and the signal light L3 is emitted from the side surface of the optical line 4A. Detection is performed by the light receiver 10 ', or the signal light L3 is detected by installing the light receiver 10 at a terminal near the user. In the system of FIG. 4A, the light receiver 10 receives the signal light L3 incident from the light incident device 9, and specifies the target core wire depending on whether or not the light is received. In the system of FIG. 4B, the light receiver 10 ′ receives the leaked light from the side surface of the optical line 4A in the bent portion 18 of the signal light L3 incident from the light incident device 9, and receives the light. The target core is identified by the presence or absence.

  By using the optical fiber coupling method or the optical fiber coupling device according to the present embodiment, the signal light L3 is incident from the side surface of the optical line 4A, and the signal light L3 is received by the light receiver 10 from one end (terminal) of the optical line 4A. Is possible. It is also possible to make a bend in the middle of the optical line 4A (bending portion 18) and receive the signal light L3 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 optical fiber coupling 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 4A to be tested, as in the case of the core wire control. Next, the pulse test light L4 is incident on the optical line 4A through the light incident device 9.

  The pulse test light L4 is sent out by the optical pulse tester 7C, and uses light such as FP-LD or DFB-LD having a wavelength longer than that of the communication light, as in the case of the core wire control. Since the wavelength is different from the communication wavelength and the long wavelength light is used at the same time, the pulse test light L4 can be efficiently incident. In-service is also possible by combining the light blocking filters 2A and 2B. With the pulse test light L4 thus incident, it is possible to perform tests such as optical fiber failure location search and 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 2B from the OTDR (Optical Time Domain Reflectometer) waveform measured using the optical fiber coupling method according to the present embodiment. Applicable to carving test. Further, by utilizing the fact that the peak amount of the reflection amount at the open end is different from that of the light blocking filter 2B, by determining the presence or absence of the light blocking filter 2B, the working optical fiber core wire and the non-working optical fiber core wire. Can be estimated.

By using the optical fiber coupling method or the optical fiber coupling 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 5 to the indoor device 1. it can.
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 radius of curvature ρ can be expressed by the equations (5) and (6) (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、（７）式で与えられる。

Also, from the geometrical calculation according to FIG. 3, ψ ₁ and ψ _i are given by equation (7).

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（８）式と（９）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 (8) and (9) as a function of the curvature radius ρ.

また、スネルの法則より、ζ_ｉは、（１０）式で与えられる。

Further, from Snell's law, ζ _i is given by equation (10).

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Ｌ３のコア２１でのシングルモード伝搬角θ_０との関係は、（１１）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 L3 incident from the incident optical fiber 14 and the single mode propagation angle θ _{0 in} the core 21 is given by (11).

本実施形態では、所定の曲率半径ρで曲げられた光線路４Ａの凸部の所定の位置（Ａ点）に、光線路４Ａの最外被覆１９とほぼ同じ屈折率の屈折率整合部材である光硬化性樹脂１３を密着させ、光硬化性樹脂１３の中で、光線路４Ａの凸部で光線路４Ａのコア２１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４Ａ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Ｌ３を光線路４Ａのコア２１に対して入射させる。

In the present embodiment, a refractive index matching member having substantially the same refractive index as that of the outermost coating 19 of the optical line 4A is provided at a predetermined position (point A) of the convex portion of the optical line 4A bent at a predetermined curvature radius ρ. The photo-curing resin 13 is brought into close contact, and in the photo-curing resin 13, the incident surface has the core center at the same height in the incident surface and the plane including all the centers of the core 21 of the optical line 4 A at the convex portion of the optical line 4 A. The core center of the end face of the optical fiber 14 is brought closer to the side surface of the convex portion of the optical line 4A at a predetermined angle ζ ₃ from the normal direction at a predetermined position (point A), and sent from the end face of the incident optical fiber 14 The signal light L3 thus made is incident on the core 21 of the optical line 4A.

With respect to the signal light L3 transmitted from the end face of the incident optical fiber 14, the core 21 and the clad 20 of the optical line 4A, the clad 20 and the outermost coating 19, and the outermost coating 19 and the light have a predetermined radius of curvature ρ. A curvature radius ρ at which no signal light L3 is totally reflected on any boundary surface of the curable resin 13 is calculated from the equations (5) to (10), and the direction becomes a predetermined position A of the convex portion of the optical line 4A. A position on the change angle (δ ₁ + δ ₂ + δ ₃ ), that is, light propagating in a single mode in the linear region of the optical line 4A is transmitted (refracted) in each boundary region of the convex portion of the optical line 4A, and the optical line The position at which the outermost coating 19 of 4A is first reached is calculated from the equations (8) and (9), the predetermined angle ζ ₃ is calculated from the equation (1), and finally the core from the side surface of the optical line 4A. So that the signal light L3 incident on 21 propagates in a single mode. In addition, the predetermined curvature radius ρ, the predetermined position A of the convex portion of the optical line 4A, and the predetermined angle ζ ₃ are all based on the expressions (5) to (10) so as to have a solution. Decide.

The predetermined position is such that the signal light L3 propagating in the single mode in the linear region of the optical line (reference numeral 4A in FIG. 3) is photocured with the outermost coating 19 on the convex portion of the optical line (reference numeral 4A in FIG. 3). The angle at which the convex portion of the optical line (reference numeral 4A in FIG. 3) starts to bend, that is, the signal light L3 is photocurable from the core 21. The sum (direction change angle: δ ₁ + δ ₂ + δ ₃ ) between the boundary layers (points A, B, and C) that are reflected and refracted before reaching the resin 13 can be obtained.

Further, in order to increase the incidence rate on the outermost coating 19, the photocurable resin 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 L3 travels substantially straight from the photocurable resin 13 side to the outermost coating 19 (ζ ₃ ≈ψ ₃ ). At this time, if the light incident fiber 14 is tilted by ψ _{3 with} respect to the normal direction of the point A, the signal light L3 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.

  As is apparent from the above description, according to the above embodiment, the signal light L3 transmitted from the incident optical fiber 14 can be efficiently incident on the core 21 from the side surface of the optical line 4A. 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 apparatus 2A, 2B ... Optical cutoff filter 3 ... Optical coupler 4A ... 1st optical line (1st optical fiber)
4B ... Second optical line (second optical fiber)
4C ... Newly installed optical line 5 ... External device 6 ... Optical input / output port 7A ... Light source for uninterruptible switching 7B ... Light source for contrast control 7C ... Optical pulse tester 8 ... Uninterruptible switching device 9 ... Light incident device 10 , 10 '... Light receiver 13 ... Photo-curing resin (refractive index matching member)
14: Optical fiber for incidence (second optical fiber)
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) L1 ... Uninterrupted Pulsed light from switching light source and signal light from in-house device L2 ... Signal light combined with pulsed light L3 ... Signal light from light source for contrast control L4 ... Pulse test light from optical pulse tester ρ ... predetermined Radius of curvature ζ ₃ ... Incident angle (δ ₁ + δ ₂ + δ ₃ ) ... Direction change angle

Claims (4)

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; and the second light Adjusting means for adjusting to emit signal light toward the side surface of the first optical fiber at a predetermined angle from the 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 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;
In the optical fiber coupling device, 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 an 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, it is cured by irradiation with light of a specific wavelength, and after the refraction, the refractive index equal to the refractive index of the outermost coating of the first optical fiber Filling means formed by filling a photo-curable resin with a rate of
Propagating light of a specific wavelength light source for curing the photocurable resin to the second optical fiber, irradiating the photocurable resin with light of the specific wavelength light source, An optical fiber coupling device comprising: a self-forming optical waveguide means for curing and self-forming the optical waveguide.   The self-forming optical waveguide means propagates light to the first optical fiber, and measures the light intensity of the leakage light from the bent portion of the first optical fiber received by the second optical fiber. The amount of change in the light intensity measured by the light intensity measuring means after the measurement means and the start of light incidence from the light source is used to form an optical waveguide between the first optical fiber and the second optical fiber. And a determination unit configured to determine that the formation of the waveguide is completed when a predetermined amount of change in light intensity corresponding to the loss of the light emitting device that decreases with the loss is reached. The optical fiber coupling device described. An optical fiber installation procedure for installing a first optical fiber in a state where a convex portion is formed by bending an arbitrary portion thereof with a predetermined curvature radius, and a first optical fiber bent with a predetermined curvature radius in the optical fiber installation procedure. An optical fiber holding procedure for holding the second optical fiber at a predetermined position of the convex portion in the bending of the optical fiber, and the center of the core of the first optical fiber in the bending portion of the first optical fiber The core of the end face of the second optical fiber installed so that the light beam irradiated from the core center of the second optical fiber in the incident portion is included in the plane including the first light at the predetermined position. An optical fiber approach procedure for approaching from a direction at a predetermined angle with respect to the normal direction of the side surface of the outermost coating of the fiber, and a signal light of a specific wavelength transmitted from the end face of the second optical fiber, One light And a light incident procedure from the side of the outermost coating of the driver so that it is incident on the core 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 of the clad and the core of the first optical fiber, and the predetermined position is a straight line of the first optical fiber. The signal light that has propagated through the region in a single mode is a position where the signal light first reaches the side surface of the outermost coating of the first optical fiber, and the predetermined angle propagates through the first optical fiber, An optical fiber coupling method in which the signal light that has reached a predetermined position is an angle at which the signal light is emitted from a boundary surface of the outermost coating of the first optical fiber,
The first optical fiber bent at a predetermined curvature radius in the optical fiber installation procedure is cured by irradiation with light of a specific wavelength at the predetermined position of the convex portion in the bending, and after the curing, the first optical fiber is cured A photocurable resin adhesion procedure for closely adhering a photocurable resin having a refractive index equal to the refractive index of the outermost coating;
Propagating the light of a specific wavelength light source for curing the photocurable resin through the second optical fiber, irradiating the photocurable resin with the light of the specific wavelength light source, An optical fiber coupling method comprising: a self-forming optical waveguide procedure for curing and self-forming the optical waveguide.   The self-forming optical waveguide procedure measures the light intensity by propagating light to the first optical fiber, and receiving light leaked from the bent portion of the first optical fiber by the second optical fiber, Corresponding to the loss of the light emitting device in which the amount of change in light intensity measured after the start of light incidence from the light source decreases with the formation of the optical waveguide between the first optical fiber and the second optical fiber The optical fiber coupling method according to claim 3, wherein it is determined that the formation of the waveguide is completed when a predetermined amount of change in light intensity is reached.

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