JP2016218348A - Optical fiber lateral input and output device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber lateral input and output device which suppresses an optical loss in an optical fiber lateral input and output technique.SOLUTION: An optical fiber lateral input and output device comprises a fixture and an input and output optical system for inputting and outputting an optical signal. The fixture has: an optical fiber 12 coated with optical fiber coating; a curved surface section for holding a bending portion at which the optical fiber 12 is bent; a flat surface section for linearly holding the optical fiber extending to both ends of the bending portion; and an abutment part formed at a predetermined position, for abutting and holding a probe fiber 13 of the input and output optical system. The probe fiber 13 is placed at the abutment part and includes an optical transmission part, which has a refraction index different from that of the optical fiber coating and is interposed between the fixture and the input and output optical system to make the optical signal transmit through.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lateral light input / output technology for inputting / outputting light from the side of a curved optical fiber, and more specifically, a bending jig for bending an optical fiber core and a side of the optical fiber. It relates to input / output devices.

  In optical line maintenance in an optical access network, an optical fiber side input / output technique described in Non-Patent Document 1 that inputs and outputs light from the side of a bent optical fiber has been proposed. The above-mentioned optical fiber side input / output device for inputting / outputting light according to the related art includes an optical transparent member having a bent shape and a probe fiber for inputting / outputting light from the side of the optical fiber.

Enobu Hamada et al., “Design examination of test light incidence mechanism using optical fiber lateral input technology”, OFT 2011-84, pp. 57-60, 2012

  In the side light input / output in which light is input / output from the side of the bent optical fiber, it is important to increase the light receiving / receiving efficiency under a certain bending loss condition. For example, in the optical communication line switching according to the related art, it is necessary to cut off the working communication line and switch to the detour line, so it is necessary to increase the bending loss and the light receiving / receiving efficiency.

  On the other hand, for applications such as test light incidence and communication light monitors that are required to have no effect on the working communication line, it is necessary to increase the light receiving and receiving efficiency while suppressing the bending loss to the extent that the working communication line is not affected. There is.

  Further, in the optical fiber side input / output device, the efficiency when the leaked light recombines with the probe fiber, that is, the optical coupling efficiency is important. If the optical coupling efficiency is low, the optical signal is lost, resulting in many problems such as deterioration of the S / N ratio.

  In related technologies, it is difficult to capture optical signals (leakage light) due to the narrow aperture angle of the probe fiber, whispering gallery mode phenomenon (part of the light leaking from the optical fiber core is covered with the optical fiber core wire) The optical coupling efficiency has reached its peak due to the phenomenon that it closes in the coating without penetrating it, and there is also a problem that the desired effect cannot be obtained especially in application to an uninterruptible switching device. .

  In order to solve the above-mentioned problems, the present invention provides an optical fiber lateral input / output technology by making the refractive index of the surface of the bending member adjacent to the optical fiber core coating higher than the refractive index of the optical fiber core coating. An object of the present invention is to provide an optical fiber side input / output device that suppresses optical loss.

  In order to achieve the above object, in the present invention, the side of the curved optical fiber core is controlled by controlling the refractive index of a bending jig made of a concave and convex member that forms a pair for bending the optical fiber. The leakage light from the direction is controlled, and the bending loss and light receiving / receiving efficiency are controlled.

Specifically, the optical fiber side input / output device according to the present invention is:
An optical fiber side input / output device having a fixing jig for inputting / outputting an optical signal and an input / output optical system,
The fixing jig is
An optical fiber coated with an optical fiber coating;
A curved surface portion for holding a bent portion for bending the optical fiber;
A plane portion that holds the optical fiber extending at both ends of the bent portion in a straight line; and
Abutting part formed in a predetermined position, abutting and holding the input / output optical system,
The input / output optical system is disposed in the abutting portion, and is interposed between the fixing jig and the input / output optical system so as to transmit an optical signal, and has a refractive index different from that of the optical fiber coating. Part.

In the optical fiber side input / output device according to the present invention,
At least a part of the light transmission part, the curved surface part, and the flat part may have a refractive index comparable to the optical fiber coating or a higher refractive index than the optical fiber coating.

In the optical fiber side input / output device according to the present invention,
At least a part of the curved surface portion and the flat surface portion may have a refractive index lower than that of the optical fiber coating.

In the optical fiber side input / output device according to the present invention,
At least a portion of the flat portion has a refractive index comparable to that of the optical fiber coating or a higher refractive index than the optical fiber coating, and at least a portion of the curved portion and the transparent member is a coating of the optical fiber. It may have a lower refractive index.

  The above inventions can be combined as much as possible.

  According to the present invention, the refractive index of the surface of the bend imparting member adjacent to the optical fiber core coating is made higher than the refractive index of the optical fiber core coating, thereby suppressing the optical loss of the optical fiber side input / output technology. A fiber side input / output device can be provided.

An example of the block diagram of the optical fiber side input / output apparatus which concerns on Embodiment 1 is shown. An example of manufacturing a bending jig in the optical fiber side input / output device according to Embodiment 1 is shown. An example of the block diagram of the bending jig in the optical fiber side input / output device which concerns on Embodiment 1 is shown. The result of having input light into the fiber to be measured in the bending jig according to Embodiment 2 and tracing the light beam is shown. An example at the time of providing a low-refractive-index wall in the plane part of the bending jig in the optical fiber side input / output device which concerns on Embodiment 3 is shown. An example in case the low refractive index wall is not provided in the plane part of the bending jig in the optical fiber side input / output device which concerns on Embodiment 3 is shown. An example in case the refractive index control area | region is provided in the curved surface part of the bending jig in the optical fiber side input / output device which concerns on Embodiment 4 is shown. An example of the enlarged view of the result of having traced the light beam of the bending jig in the optical fiber side input / output device which concerns on Embodiment 4 is shown. The beam width of leaked light when the refractive index of the refractive index control region according to the present embodiment is changed is shown.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. These embodiments are merely examples, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
The optical fiber side input / output device according to this embodiment includes a fixing jig and an input / output optical system. The bending jig that functions as a fixing jig includes an optical fiber, a curved surface portion, a flat surface portion, and an abutting portion, and the probe fiber that functions between the fixing jig and the input / output optical system has a light transmitting portion. Intervene. It shows that bending loss and input / output efficiency are increased by making the refractive index of the bending jig provided in the optical fiber side input / output device higher than that of the optical fiber coating.

  FIG. 1 shows a bending jig for controlling the refractive index in the bending jig 11 used in the optical fiber side input / output device and the amount of leaked light from the optical fiber core wire 12 to control bending loss and light receiving / receiving efficiency. FIG. Here, the optical fiber side input / output device further includes a probe fiber 13 that functions as an optical input / output optical system. The probe fiber 13 is disposed at an abutting portion formed at a position where the optical fiber and the probe fiber 13 in the bending jig 11 can be optically connected so as to abut and hold the probe fiber 13.

  As shown in FIG. 2, a bending jig 11 was produced in order to form a bend with a bending radius of 2 mm and an opening angle of 160 degrees in the optical fiber core 12 containing the optical fiber. As the material of the transparent member functioning as the light transmitting portion, acrylic and polycarbonate, which are generally used as an optical plastic as an example and are easy to process, are used here.

  The refractive indexes of the acrylic and polycarbonate used in the optical communication band (1.31 to 1.55) are approximately 1.47 and 1.57, respectively, and the refractive index of the optical fiber coating is approximately 1.5. In order to input / output optical signals from / to the side of the optical fiber, the input / output optical system uses a GI fiber probe having a GRIN lens connected to the tip, and the GRIN lens has a beam waist diameter of about 230 μm. .

The upper and lower parts of Table 1 show the measurement results for two types of single-mode fibers (R30), which are commonly used at present, from different manufacturers. The light receiving efficiency in Table 1 indicates the ratio between the optical power input to the optical fiber to be measured and the optical power output from the latter stage of the fiber probe. From Table 1, it can be seen that a jig made of polycarbonate has higher bending loss and light receiving efficiency for both fibers.

(Embodiment 2)
In this embodiment, it is shown that bending loss can be reduced by making the refractive index of the bending jig 11 lower than the refractive index of the optical fiber coating. As shown in FIG. 3, a bending jig is assumed to form a bend with a bending radius of 2 mm and an opening angle of 160 degrees in an optical fiber. Here, as an example, the material of the transparent member is fluororesin (refractive index 1.33). To do.

  FIG. 4 shows the result of tracing light by inputting light into the fiber to be measured. FIG. 4 shows that the optical signal is confined within the optical fiber coating. Thereby, bending loss can be reduced. Note that, by setting the refractive index of the transparent member to 1.37 or less, an optical signal can be confined in the optical fiber coating as described above.

(Embodiment 3)
In the present embodiment, it is shown that the input / output efficiency can be improved while reducing the bending loss. In order to form a bend with a bend radius of 2 mm and an opening angle of 160 degrees in the optical fiber, a bending jig 11 is assumed. Here, as an example, the material of the transparent member is polycarbonate (refractive index 1.57).

  Further, as shown in the second embodiment, in order to confine the optical signal in the optical fiber coating, a low refractive index wall 15 (for example, a fluororesin) is provided on the flat portion as shown in FIG. FIGS. 5 and 6 show the results of tracking the light beam by inputting light into the fiber under measurement when the low refractive index wall 15 is provided or not provided, respectively. FIG. 5 shows a case where the low refractive index wall 15 is provided in the flat portion, and FIG. 6 is a view showing a case where the low refractive index wall 15 is not provided in the flat portion. 5 and 6, it can be seen that by providing the low refractive index wall 15, bending loss can be reduced without changing the position and amount of light leaking from the side of the optical fiber.

(Embodiment 4)
In the present embodiment, it is shown that the input / output efficiency is improved while reducing the bending loss, and that the leakage pattern of the optical signal output from the side of the optical fiber can be controlled. In order to form a bend with a bend radius of 2 mm and an opening angle of 160 degrees in the optical fiber, a bending jig is assumed. Here, as an example, the material of the transparent member is polycarbonate (refractive index of 1.57).

  Further, as shown in the second embodiment, in order to confine the optical signal in the optical fiber coating, a low refractive index wall 15 (for example, a fluororesin) is provided on the flat portion as shown in FIG. Further, as shown in FIG. 7, a refractive index control region 16 (for example, acrylic) is disposed on the curved surface portion. FIG. 7 shows the result of tracking the light beam by inputting light into the measured fiber when the refractive index of the refractive index control region 16 is 1.47. FIG. 8 shows an enlarged view of the result of tracing the light beam.

  5 and 7, it can be seen that the light leaking from the side of the optical fiber can be condensed by appropriately setting the refractive index of the refractive index control region 16. This is because the leaked light from the bent portion is refracted in the direction of the optical fiber because it proceeds from the higher refractive index to the lower one, but the leaked light from the straight portion proceeds from the lower refractive index to the higher one. Since the light is refracted in the opposite direction of the optical fiber, leakage light can be collected.

  FIG. 9 shows the beam width of leaked light when the refractive index of the refractive index control region 16 is changed. It can be seen that the beam width is narrow when the refractive index of the refractive index control region 16 is about 1.42. This makes it easy for leaked light to enter the probe fiber 13 as described in the first embodiment, and the light receiving efficiency is improved. It is also possible to control the condensing position of the leaked light by controlling the refractive index of the refractive index control region 16.

  According to the optical fiber side input / output device according to this embodiment described above, the bending loss and the light receiving / receiving efficiency are controlled by controlling the refractive index of the bending jig 11 for bending the optical fiber core wire 12. Therefore, it is possible to increase the light receiving / receiving efficiency while suppressing the bending loss, and to increase the bending loss and the light receiving / receiving efficiency. For example, by making the refractive index of the bending jig 11 higher than the coating of the optical fiber core wire 12, the leakage light from the optical fiber core wire 12 can be increased, and the loss and light receiving / receiving efficiency can be increased.

  Further, by making the refractive index of the bending jig 11 lower than that of the coating of the optical fiber core wire 12, the bending loss can be reduced and the light incident efficiency can be increased. When the optical fiber core 12 is bent with a small bending radius, the light leaked from the core is confined within the coating of the optical fiber core 12 to be in the whispering gallery mode, resulting in multipath interference (MPI) and signal quality degradation. However, the whispering gallery mode can be suppressed by making the refractive index of the bending jig 11 higher than the coating of the optical fiber core wire 12. By appropriately setting the refractive index distribution of the bending jig, the position of the leakage light from the bending fiber and the distribution of the leakage light can be controlled.

  The present invention can be applied to the information communication industry.

11: Bending jig 12: Optical fiber core wire 13: Probe fiber 15: Low refractive index wall 16: Refractive index control region

Claims (4)

An optical fiber side input / output device having a fixing jig for inputting / outputting an optical signal and an input / output optical system,
The fixing jig is
An optical fiber coated with an optical fiber coating;
A curved surface portion for holding a bent portion for bending the optical fiber;
A plane portion that holds the optical fiber extending at both ends of the bent portion in a straight line; and
Abutting part formed in a predetermined position, abutting and holding the input / output optical system,
The input / output optical system is disposed in the abutting portion, and is interposed between the fixing jig and the input / output optical system so as to transmit an optical signal, and has a refractive index different from that of the optical fiber coating. Part
An optical fiber side input / output device comprising: The at least part of the light transmission part, the curved surface part, and the flat part has a refractive index comparable to the optical fiber coating or a higher refractive index than the optical fiber coating. Optical fiber side input / output device. 2. The optical fiber side input / output device according to claim 1, wherein at least a part of the curved surface portion and the flat surface portion has a refractive index lower than that of the optical fiber coating. At least a portion of the flat portion has a refractive index comparable to that of the optical fiber coating or a higher refractive index than the optical fiber coating, and at least a portion of the curved portion and the transparent member is a coating of the optical fiber. 2. The optical fiber side input / output device according to claim 1, wherein the optical fiber side input / output device has a lower refractive index.

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