JP2019070740A - Optical fiber side input-output device and method for providing distortion - Google Patents

Abstract

To provide an optical fiber side input-output device and a method for providing a distortion that can attain reduction in a side pressure loss and increase in the efficiency of optical input/output when a distortion is formed in a tube-equipped optical fiber and light is output or input from a distorted part with a probe.SOLUTION: The optical fiber side input-output device according to the present invention reduces a side pressure loss by pressing the area around the top of the distortion gently enough to maintain a space between the optical fiber and the protective tube, by using not only a convex fixture to distort and press the tube-equipped fiber at its top but also a pressing fixture. The input-output device also obtains a high level of efficiency of inputting or outputting light by increasing the distance for which the protective tube and the concave fixture are in contact with each other.SELECTED DRAWING: Figure 4

Description

  The present disclosure relates to an optical fiber side input / output device that inputs and outputs light from the side of a bent optical fiber, and a method of applying bending to an optical fiber.

  An optical fiber side input / output device has been proposed that bends an optical fiber with respect to an optical fiber covered with a protective tube (optical fiber with a tube) and inputs and outputs light from the bend using a probe (for example, See Non-Patent Document 1.).

  FIG. 1 is a view for explaining the cross section of the tube-mounted optical fiber 101. As shown in FIG. In the optical fiber with tube 101, a protective tube 32 covers a core wire 31 consisting of a core, a clad and a coating, and an air gap is present between the core wire 31 and the protective tube 32.

  When such a tubed optical fiber is bent, since the rigidity of the protective tube and the optical fiber core wire differs, it is not uniformly bent as shown in FIG. 2 and a gap is generated between the optical fiber core wire and the tube. Then, due to the presence of the air gap, the leaked light from the core of the optical fiber core is reflected at the interface between the coating of the optical fiber core and the air gap, and the intensity of the light leaked to the outside of the optical fiber core decreases significantly. Do.

  Therefore, Non-Patent Document 1 proposes a side input / output device having a mechanism for collapsing the protective tube so that the air gap is eliminated when the tubed optical fiber is bent. FIG. 3 is a view for explaining an optical fiber side input / output device disclosed in Non-Patent Document 1. As shown in FIG. The lateral input / output device of Non-Patent Document 1 squeezes only the top of the bending of the protective tube to eliminate the gap between the optical fiber core wire and the protective tube, thereby suppressing the decrease in light intensity of leaked light due to the gap. Further, since the side pressure applied to the optical fiber is only near the bending apex, the loss due to the side pressure is reduced and the influence on the current communication is reduced. It has a function to switch between the time of bending release and the time of bending, and the distance between the concave jig and the convex jig, that is, the amount of crushing the tube becomes a predetermined amount S, and S should be set to an appropriate amount. Low bending loss and high input / output efficiency.

Unexamined-Japanese-Patent No. 2015-121460

Uematsu et al., "Side Light I / O to Optical Fibers Protected by Transparent Tubes," IEICE Society Conference, B-13-20, September 2017. T. UematSu, et. al. “High-efficiency light injection and extraction uSing fiber bending”, OFC, W2A. 15, Mar. 2017.

  As shown in FIG. 3, Non-Patent Document 1 proposes a method in which only the bending apex portion of the tube is crushed to eliminate the gap between the optical fiber core wire and the protective tube. In such a method, the region A between the protective tube and the concave jig on the path along which the output light (leakage light from the bending fiber to the probe) and the input light (input light from the probe to the bending fiber) propagate It is necessary to eliminate the air gap in the portion enclosed by the broken line in FIG. However, in the method of Non-Patent Document 1, there is a problem that the portion of the convex jig pressing the tube-mounted optical fiber is deviated from the region A, and the contact between the protective tube and the concave jig in the region A is insufficient. Further, in the method of Patent Document 1, there is a problem that extra side pressure is applied to the optical fiber core wire and the loss is increased because the entire bending portion and the straight portion are crushed.

  Then, in order to solve the above-mentioned subject, when forming a bend in the optical fiber with a tube, and inputting and outputting light using a probe from a bending part, reduction of side pressure loss and input and output efficiency of light It is an object of the present invention to provide an optical fiber side input / output device and a bending method which can achieve both improvement.

  In order to achieve the above object, in the optical fiber side input / output device according to the present invention, in addition to a convex jig for bending an optical fiber with a tube to crush the apex, light is used around the bending apex using a holding jig. It was decided to obtain high light input / output efficiency by reducing the side pressure loss by crushing the fiber and the protective tube so as not to contact each other, and increasing the distance of contact between the protective tube and the concave jig.

Specifically, the first optical fiber side input / output device according to the present invention is
A protective tube is inserted into a cavity which is longitudinally curved with respect to the tubed optical fiber having a structure in which the protective tube covers the cored wire, and light is input to and output from the cored wire of the tubed optical fiber to which bending is given. A first jig having a holding portion for holding the probe optical fiber;
A second jig having a convex portion that contacts only the portion to be the apex of the bend formed in the optical fiber with tube;
A restraining jig which contacts the side opposite to the first jig of the region on the path of the light that is input / output between the optical fiber with tube and the probe optical fiber in the optical fiber with tube,
The direction in which the concave portion of the first jig and the convex portion of the second jig approach so that the closest contact distance S between the concave portion of the first jig and the convex portion of the second jig is S> 0. A first pressing portion that applies a pressing force to the tube to form the bend in the optical fiber with tube;
The concave portion of the first jig and the depression so that the closest contact distance U between the concave portion of the first jig and the holding jig is D>U> S (D is the diameter of the protective tube before crushing). A second pressing portion that applies a pressing force in a direction in which the jig approaches
Equipped with

The second optical fiber side input / output device according to the present invention is
A protective tube is inserted into a cavity which is longitudinally curved with respect to the tubed optical fiber having a structure in which the protective tube covers the cored wire, and light is input to and output from the cored wire of the tubed optical fiber to which bending is given. A first jig having a holding portion for holding the probe optical fiber;
The convex portion in contact with the portion to be the apex of the bend formed in the optical fiber with tube, and the light input / output between the optical fiber with tube and the probe optical fiber among the optical fibers with tube A second jig having a restraining portion in contact with the first jig opposite to the region on the path of
The closest contact distance S between the concave portion of the first jig and the convex portion of the second jig is S> 0, and the concave portion of the first jig and the restraining portion of the second jig A pressing force is applied in the direction in which the concave portion of the first jig and the convex portion of the second jig approach so that the closest contact distance U becomes D>U> S (D is the diameter of the protective tube before crushing). A pressing portion that applies and forms the bend in the optical fiber with tube;
Equipped with

Furthermore, the bending method according to the present invention is
A protective tube is inserted into a cavity which is longitudinally curved with respect to the tubed optical fiber having a structure in which the protective tube covers the cored wire, and light is input to and output from the cored wire of the tubed optical fiber to which bending is given. A first jig having a holding portion for holding the probe optical fiber;
A second jig having a convex portion that contacts only the portion to be the apex of the bend formed in the optical fiber with tube;
A bending method for bending the optical fiber with tube using an optical fiber side input / output device comprising:
The direction in which the concave portion of the first jig and the convex portion of the second jig approach so that the closest contact distance S between the concave portion of the first jig and the convex portion of the second jig is S> 0. Apply pressure to the tube to form the bend in the tubed optical fiber,
In the tubed optical fiber, the side opposite to the first jig of the region on the path of the light input / output between the tubed optical fiber and the probe optical fiber is suppressed by a restraining portion, The optical fiber with tube and the recess of the first jig are set such that the closest contact distance U between the recess of the jig and the restraining portion is D>U> S (D is the diameter of the protective tube before crushing). Put in close contact with,
It is characterized by

  In this optical fiber side input / output device, in addition to forming a bend in the optical fiber with tube using the second jig, the optical fiber with tube is adhered to the area A using the holding jig or the holding portion. . As a result, the light input / output efficiency of the optical fiber with tube is improved. Moreover, the loss by the side pressure to the optical fiber with a tube can also be reduced by adjusting the pressing force of the 2nd jig which has the pressing force thru | or the pressing part of a holding jig.

  Therefore, according to the present invention, when forming a bend in an optical fiber with a tube and inputting / outputting light using a probe from a bending portion, an optical fiber side capable of achieving both reduction in lateral pressure loss and improvement in light input / output efficiency It is possible to provide an input / output device and a bending method.

  The tip of the holding jig of the optical fiber side-to-side input / output device according to the present invention is wedge-shaped, and the angle φ formed by the surface in contact with the optical fiber with tube and the direction of pressing force is φ ≦ θ / 2 It features. The restraining portion of the second jig is characterized in that an angle φ formed by the surface in contact with the optical fiber with a tube and the direction of pressing force is φ ≦ θ / 2. Is the bending angle given to the optical fiber with tube by the first jig and the second jig.

The convex portion of the second jig of the optical fiber side-to-side input / output device according to the present invention has a tip shape that is a part of a side surface of a cylinder, and a direction in which the pressing force is applied to the generatrix of the cylinder Perpendicular to the longitudinal direction of the optical fiber with tube,
The radius r of the side surface of the cylinder is r ≦ R−d−2t
It is characterized by satisfying. Where d is the diameter of the core of the optical fiber with a tube, t is the thickness of the tube, and R is the radius of curvature of the recess of the first jig.

  The present invention is an optical fiber side input method capable of achieving both reduction of side pressure loss and improvement of light input / output efficiency when forming a bend in an optical fiber with a tube and using a probe to input and output light from a bending portion. An output device and a bending method can be provided.

It is a figure explaining the cross section of the optical fiber with a tube. It is a figure explaining the subject of the optical fiber with a tube. It is a figure explaining the conventional optical fiber side input-output device. It is a figure explaining the 1st optical fiber side way input-output device concerning the present invention. It is a figure explaining the 2nd jig of the 1st optical fiber side way input-output device concerning the present invention. It is a figure explaining the 2nd optical fiber side way input-output device concerning the present invention. It is a figure explaining the effect of the optical fiber side way input-output device concerning the present invention. It is a figure explaining the effect of the optical fiber side way input-output device concerning the present invention.

  Embodiments of the invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, components having the same reference numerals denote the same components.

(Embodiment 1)
FIG. 4 is a view for explaining the outline of the optical fiber side input / output device 301 of this embodiment. The optical fiber side input / output device 301 is
A recess 21 which is curved in the longitudinal direction with respect to the tubed optical fiber 101 having a structure in which the protective tube 32 covers the cored wire 31 with a gap in between, and light with respect to the cored wire 31 of the tubed optical fiber 101 to which bending is given. A first jig 11 having a holding portion 51 for holding a probe optical fiber 50 for inputting and outputting
A second jig 12 having a convex portion 22 contacting only a portion to be the apex of the bend formed in the optical fiber 101 with a tube;
And a holding jig 13 in contact with the first jig 11 of the area A on the path of the light input / output between the optical fiber 101 with a tube and the probe optical fiber 50 in the optical fiber 101 with a tube and ,
The concave portion 21 of the first jig 11 and the convex portion 22 of the second jig 12 such that the closest contact distance S between the concave portion 21 of the first jig 11 and the convex portion 22 of the second jig 12 is S> 0. A pressing force is applied in a direction in which the first and second optical fibers 101 approach each other to form the bend in the optical fiber 101 with a tube;
The recessed portion 21 of the first jig 11 and the closest contact distance U between the recessed portion 21 of the first jig 11 and the holding jig 13 satisfy D>U> S (D is the diameter of the protective tube 32 before crushing). A second pressing portion 15 for applying a pressing force in a direction in which the pressing jig 13 approaches
Equipped with
FIG. 4 shows a state of the tube-mounted optical fiber 101 to which bending is applied, and the protective jig 32 is crushed by pushing the second jig 12 and the holding jig 13 in the direction of the first jig 11 by a pressing force. It explains the later state.

The first pressing portion 14 has a function of switching between bending release and bending application, and at the time of bending application, the optical fiber 101 with a tube so that the distance between the first jig 11 and the second jig 12 becomes a predetermined amount S. Apply pressure to
The second pressing unit 15 applies a pressing force to the optical fiber with tube 101 so that the distance between the first jig 11 and the holding jig 13 is a distance U larger than a predetermined amount S. By making the distance U larger than the predetermined amount S and smaller than the diameter D of the protective tube 32 before crushing, the optical fiber core wire 31 and the protective tube 32 are prevented from contacting each other.

  With this design, as shown in FIG. 4, when forming a bend in the optical fiber 101 with a tube by the first jig 11 and the second jig 12, the protective tube 32 near the apex of the bend to be formed Not only that, the protective tube 32 can be crushed in the direction of the area A by the holding jig 13 so that the recess 21 and the protective tube 32 can be sufficiently brought into contact with each other. Then, by setting the distance between the first jig 11 and the holding jig 13 to U, it can be crushed to such an extent that the optical fiber core wire 31 and the protective tube 32 do not contact, and the side pressure on the optical fiber core wire 31 is prevented. it can.

FIG. 5 is a view for explaining the second jig 12. 5A is a top view, FIG. 5B is a side view, and FIG. 5C is a perspective view. In the second jig 12, the tip shape of the convex portion 22 is a part of the side surface of the cylinder, and the direction (Z direction) in which the pressing force is applied to the generatrix of the cylinder and the longitudinal direction of the tubed optical fiber 101 ( Perpendicular to the X direction) (Y direction).
Here, the radius r of the side surface of the cylinder of the convex portion 22 satisfies r ≦ Rd−2t. Here, d is the diameter of the core wire 31, t is the thickness of the protective tube 32, and R is the radius of curvature of the recess 21 of the first jig 11.

  The tip of the holding jig 13 is wedge-shaped, and preferably, an angle φ formed by the surface in contact with the optical fiber with tube 101 and the direction of pressing force is φ ≦ θ / 2. However, θ is a bending angle given to the optical fiber with tube 101 by the first jig 11 and the second jig 12.

Second Embodiment
FIG. 6 is a view for explaining the outline of the optical fiber side input / output device 302 of this embodiment. The optical fiber side input / output device 302 is
A recess 21 which is curved in the longitudinal direction with respect to the tubed optical fiber 101 having a structure in which the protective tube 32 covers the cored wire 31 with a gap in between, and light with respect to the cored wire 31 of the tubed optical fiber 101 to which bending is given. A first jig 11 having a holding portion 51 for holding a probe optical fiber 50 for inputting and outputting
Among the optical fiber 101 with a tube and the optical fiber 101 with a tube, the input / output between the optical fiber 101 with a tube and the probe optical fiber 50 among the convex portion 22 in contact with the portion to be the apex of the bend formed in the optical fiber 101 with a tube A second jig 12a having a pressing portion 23 in contact with the side opposite to the first jig 11 of the region A on the light path;
The depression 21 of the first jig 11 and the suppression of the second jig 12a such that the closest contact distance S between the depression 21 of the first jig 11 and the projection 22 of the second jig 12a is S> 0. The concave portion 21 of the first jig 11 and the convex portion 22 of the second jig 12 a are arranged such that the closest contact distance U with the portion 23 is D>U> S (D is the diameter of the protective tube 32 before crushing). A pressing portion 14a that applies a pressing force in a direction to approach and forms the bend in the optical fiber 101 with a tube;
Equipped with
FIG. 6 shows a state of the tube-mounted optical fiber 101 to which bending is applied, and illustrates a state after pressing the second jig 12a in the direction of the first jig 11 with a pressing force and crushing the protective tube 32. ing.

  The second jig 12a of the present embodiment has a structure in which the second jig 12 and the holding jig 13 described in the first embodiment are integrated. For this reason, there is only one pressing portion that generates a pressing force. That is, the pressing portion 14a has a function of switching between the bending release time and the bending application time, and at the bending application time, the distance between the first jig 11 and the second jig 12 becomes a predetermined amount S, and the first jig A pressing force is applied to the optical fiber with tube 101 such that the distance between the distance 11 and the restraining portion 23 is a distance U larger than the predetermined amount S. The radius r of the convex portion 22, the bending angle θ, the angle φ, the distance S, and the distance U are the same as those described in the first embodiment. Moreover, although the optical fiber side input-output device 302 of FIG. 6 arrange | positions the suppression part 23 on both sides of the convex part 22 in the longitudinal direction of the optical fiber 101 with a tube, the suppression part 23 may be only the area | region A side.

  The optical fiber side input / output device 302 includes the second jig 12a in which the convex part 22 and the holding part 23 are integrated, so that only one pressing part is necessary. The structure is simpler than that of the above.

(Example)
Using the optical fiber side input / output device 301 of Embodiment 1 or the optical fiber side input / output device 302 of Embodiment 2, bending was applied to the optical fiber with tube 101 as follows.
First, the concave portion 21 of the first jig 11 and the convex of the second jig 12 such that the closest contact distance S between the concave portion 21 of the first jig 11 and the convex 22 of the second jig 12 is S> 0. A pressing force is applied in the direction in which it approaches the portion 22 to form a bend in the optical fiber with tube 101.
Then, in the optical fiber 101 with a tube, the opposite side of the first jig 11 of the region A on the path of the light input / output between the optical fiber 101 with a tube and the probe optical fiber 50 is held down by the jig 13 ( The tubed optical fiber 101 is first constrained so that the closest contact distance U between the recess 21 of the first jig 11 and the pressing jig 13 (pressing portion 23) is D>U> S. Close contact with the recess 21 of the jig 11.

  The bending is performed using the optical fiber with tube 101 bent by using the optical fiber side input / output device 301 or the optical fiber side input / output device 302 and the optical fiber side input / output device 300 described in FIG. The bending loss and the output efficiency were compared with the given tubed optical fiber 101.

Evaluation conditions are as follows.
Probe optical fiber 50: double clad fiber with a GRIN lens connected to the tip (see Non-Patent Document 2)
・ Tube diameter: 0.9 mm
・ Tube thickness t: 0.28 mm
· Diameter d of optical fiber core: 0.25 mm
・ Concave surface radius of curvature R: 2.125 mm
· Bending angle θ of concave jig: 170 degrees · Curvature radius of convex surface r: 1.0 mm
・ Angle φ of holding jig: 80 degrees

  FIG. 7 is a diagram comparing bending loss, and FIG. 8 is a diagram comparing output efficiency. In each case, the measurement result is an average value of 5 times. The wavelength used is 1550 nm for measurement of bending loss and 1310 nm for measurement of output efficiency. As shown in FIGS. 7 and 8, the optical fiber side input / output device 301 or the optical fiber side input / output device 302 according to the present embodiment has lower bending loss compared to the conventional optical fiber side input / output device 300. Regardless, it can be seen that the output efficiency is improved by 6.6 dB or more. That is, since the holding jig 13 or the holding portion 23 holds the tubed optical fiber 101 against the region A, the output efficiency is improved, and the pressure is appropriately set to reduce the side pressure on the core wire 31. The loss was also reduced.

11: first jig 12, 12a: second jig 13: pressing jig 14: first pressing section 14a: pressing section 15: second pressing section 21: concave section 22: convex section 23: pressing section 31: core wire 32: Protective tube 50: Probe optical fiber 51: Holding portion 55: Optical fiber 101: Optical fiber with tube 300, 301, 302: Optical fiber side input / output device

Claims (6)

A protective tube is inserted into a cavity which is longitudinally curved with respect to the tubed optical fiber having a structure in which the protective tube covers the cored wire, and light is input to and output from the cored wire of the tubed optical fiber to which bending is given. A first jig having a holding portion for holding the probe optical fiber;
A second jig having a convex portion that contacts only the portion to be the apex of the bend formed in the optical fiber with tube;
A restraining jig which contacts the side opposite to the first jig of the region on the path of the light that is input / output between the optical fiber with tube and the probe optical fiber in the optical fiber with tube,
The direction in which the concave portion of the first jig and the convex portion of the second jig approach so that the closest contact distance S between the concave portion of the first jig and the convex portion of the second jig is S> 0. A first pressing portion that applies a pressing force to the tube to form the bend in the optical fiber with tube;
The concave portion of the first jig and the depression so that the closest contact distance U between the concave portion of the first jig and the holding jig is D>U> S (D is the diameter of the protective tube before crushing). A second pressing portion that applies a pressing force in a direction in which the jig approaches
Fiber side input / output device with. The optical fiber side according to claim 1, wherein the tip of the holding jig is wedge-shaped, and an angle φ formed by the surface in contact with the optical fiber with a tube and the direction of pressing force is φ ≦ θ / 2. Input / output device.
Is the bending angle given to the optical fiber with tube by the first jig and the second jig. A protective tube is inserted into a cavity which is longitudinally curved with respect to the tubed optical fiber having a structure in which the protective tube covers the cored wire, and light is input to and output from the cored wire of the tubed optical fiber to which bending is given. A first jig having a holding portion for holding the probe optical fiber;
The convex portion in contact with the portion to be the apex of the bend formed in the optical fiber with tube, and the light input / output between the optical fiber with tube and the probe optical fiber among the optical fibers with tube A second jig having a restraining portion in contact with the first jig opposite to the region on the path of
The closest contact distance S between the concave portion of the first jig and the convex portion of the second jig is S> 0, and the concave portion of the first jig and the restraining portion of the second jig A pressing force is applied in the direction in which the concave portion of the first jig and the convex portion of the second jig approach so that the closest contact distance U becomes D>U> S (D is the diameter of the protective tube before crushing). A pressing portion that applies and forms the bend in the optical fiber with tube;
Fiber side input / output device with. The side of the optical fiber according to claim 3, wherein an angle φ formed by the surface of the second jig and the direction of the pressing force with the surface in contact with the optical fiber with a tube is φ ≦ θ / 2. I / O device.
Is the bending angle given to the optical fiber with tube by the first jig and the second jig. The convex portion of the second jig has a tip shape that is a part of a side surface of a cylinder, and the generatrix of the cylinder is perpendicular to the direction in which the pressing force is applied and the longitudinal direction of the optical fiber with tube ,
The radius r of the side surface of the cylinder is r ≦ R−d−2t
The optical fiber side input / output device according to any one of claims 1 to 4, wherein
Where d is the diameter of the core of the optical fiber with a tube, t is the thickness of the tube, and R is the radius of curvature of the recess of the first jig. A protective tube is inserted into a cavity which is longitudinally curved with respect to the tubed optical fiber having a structure in which the protective tube covers the cored wire, and light is input to and output from the cored wire of the tubed optical fiber to which bending is given. A first jig having a holding portion for holding the probe optical fiber;
A second jig having a convex portion that contacts only the portion to be the apex of the bend formed in the optical fiber with tube;
A bending method for bending the optical fiber with tube using an optical fiber side input / output device comprising:
The direction in which the concave portion of the first jig and the convex portion of the second jig approach so that the closest contact distance S between the concave portion of the first jig and the convex portion of the second jig is S> 0. Apply pressure to the tube to form the bend in the tubed optical fiber,
In the tubed optical fiber, the side opposite to the first jig of the region on the path of the light input / output between the tubed optical fiber and the probe optical fiber is suppressed by a restraining portion, The optical fiber with tube and the recess of the first jig are set such that the closest contact distance U between the recess of the jig and the restraining portion is D>U> S (D is the diameter of the protective tube before crushing). Put in close contact with,
A bending method characterized in that

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