JP4496851B2 - Optical transmission device with optical fiber loss adjustment function - Google Patents

Description

  The present invention relates to an optical transmission apparatus having an optical fiber loss adjustment function, and more particularly to an optical transmission apparatus having an optical fiber loss adjustment function for adjusting a loss of an optical signal level transmitted using an optical fiber.

  In a multi-relay wavelength division multiplexing transmission system, many optical multiplexers / demultiplexers, optical amplifiers, and the like are used. These devices are configured by fusing a plurality of optical components into a fiber, but for the purpose of suppressing variations in the loss of a plurality of main signals, a loss of about several dB is achieved by shifting the core of the optical fiber to be connected. A loss-increasing connection that intentionally gives is applied.

  On the other hand, an optical attenuator is generally used for loss adjustment (level adjustment) of an optical signal transmitted through an optical fiber. In this optical attenuator, an optical fiber is wound around a cylindrical core member a plurality of times, and an optical signal passing through the optical fiber is attenuated by radiation loss, and the diameter of the core member and the number of turns of the optical fiber are set. There is known a method of adjusting the light reduction quantity by adjusting (see, for example, Patent Documents 1 and 2).

  In addition, in an optical attenuator made of an optical fiber that is bent into a predetermined circular shape by being in contact with the protrusion and placed on the pedestal surface by contacting the protrusion, an optical fiber is initially formed by the protrusion. By reducing the radius of curvature of the optical fiber, the light attenuation per turn is increased and adjusted, and then by increasing the radius of curvature of the optical filer, the optical attenuation per turn is reduced and finely adjusted. A method of adjusting the optical signal level (light attenuation amount) without changing the number of turns by performing adjustment is also conventionally known (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 10-20123 Japanese Patent Laid-Open No. 2-129603 JP 2001-228337 A

  However, when the loss increasing connection is used as an optical transmission device having an optical fiber loss adjusting function, the loss increasing connection requires an expensive optical fiber fusion splicer having this function, and much work time is required. Therefore, an increase in manufacturing cost and lead time is a problem. In addition, it is difficult for any of the optical transmission devices having the optical fiber loss adjustment function using the conventional optical attenuators described in Patent Documents 1 to 3 to adjust the optical fiber loss to an arbitrary value.

  The present invention has been made in view of the above points, and an object thereof is to provide an optical transmission device having an optical fiber loss adjustment function capable of adjusting the loss of an optical fiber to an arbitrary value.

  Another object of the present invention is to provide an optical transmission apparatus having an optical fiber loss adjustment function capable of adjusting the loss of an optical fiber with an inexpensive configuration without requiring work.

  In order to achieve the above object, an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention is as shown in the principle configuration diagram of FIG. That is, as shown in FIG. 1, the present invention has an optical fiber loss adjustment function of an optical transmission system that transmits an optical signal from an input connector 11 to an output connector 15 through an optical component 12 and an optical loss adjustment bobbin. The optical transmission apparatus is characterized in that a bobbin 13 having a plurality of curvature radii around which the optical fiber is wound is provided as an optical loss adjusting bobbin. In FIG. 1, the bobbin 13 having a plurality of radii of curvature is wired to the output connector 15 by an optical fiber via a surplus length processing bobbin 14 having a large curvature radius. Not necessary.

  In the present invention, the optical signal input to the input connector 11 is guided by an optical component 12 to a bobbin 13 having a plurality of radii of curvature after being attenuated by, for example, AdB. The bobbin 13 having a plurality of curvature radii is composed of a plurality of bobbins having a plurality of different curvature radii (which are smaller than that of the extra-length processing bobbin 14). The optical fiber loss is adjusted by attenuating the optical signal level according to the number of turns of the fiber. For example, if the bobbin 13 having a plurality of curvature radii is composed of n bobbins having different curvature radii (n is an integer of 2 or more), when an optical fiber is wired on each bobbin, B1 and B1 are caused by bending loss. Attenuates by B2,..., Bn (dB / circumference).

  Therefore, at the output of the loss adjustment bobbin 13, the optical signal is further attenuated according to the number of turns of n bobbins (n is an integer of 2 or more) having different radii of curvature. Since the surplus length processing bobbin 14 has a sufficiently larger radius of curvature than that of the loss adjusting bobbin 13, the loss of the optical signal when the optical fiber is laid on the surplus length processing bobbin 14 is almost 0 dB, and the output connector is used as it is. 15 is output.

Here, in the present invention, as the bobbin 13 having the plurality of curvature radii described above, one bobbin having a weight shape in which the curvature radius of the circumferential position where the optical fiber is wound around the outer peripheral surface is different, or a bobbin capable of changing the curvature radius Can be used. Further, in the present invention, instead of the bobbin 13, a box-shaped optical loss adjusting component in which the optical fiber is wired inside to generate a bending loss can be used.

According to the present invention, the loss can be adjusted freely by coarsely adjusting and finely increasing the loss by arranging the optical fiber inside a bobbin or box-shaped part having a plurality of curvature radii. Therefore, the loss adjustment work can be performed without knowing the know-how of fiber fusion, the loss adjustment work is easy, and the loss value can be adjusted accurately. Further, even when readjustment is necessary, the amount of loss can be adjusted by increasing or decreasing the circumferential position where the optical fiber is wound around the optical loss adjustment bobbin or the curvature radius of the bobbin .

  In addition, according to the present invention, it is only necessary to wire the optical fiber in the cylinder of the bobbin, so that an expensive fusion machine is not required and the cost can be reduced. The increase loss connection here can intentionally give a loss of about several dB by shifting the core of the fiber to be connected. Conventionally, it has been necessary to use an expensive optical fiber fusion machine having an increased loss connection function when adjusting the loss and perform the optical fiber fusion, but the optical fiber fusion can be made unnecessary.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 2 shows a configuration diagram of a first embodiment of an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention. In the figure, an input connector 21 is connected to an output connector 25 by an optical fiber via an optical component 22 having a loss of AdB, a loss adjusting bobbin 23 having a small curvature radius, and a surplus length processing bobbin 24 having a large curvature radius. Yes.

  In the present embodiment, the radius of curvature of the optical fiber becomes equal to the radius of curvature of the loss adjustment bobbin 23 by arranging the optical fiber extending from the optical component 22 on the loss adjustment bobbin 23. The bending loss of the optical fiber is determined by the radius of curvature and the length of the bent portion. Therefore, by setting the radius of the loss adjustment bobbin 13 so that the loss of BdB is added by making one round of the optical fiber, the loss of the optical signal in the loss adjustment bobbin 13 is (B × (loss adjustment bobbin The number of turns at 23)) dB.

  Finally, the remaining optical fiber is wound around a surplus length processing bobbin 24 having a radius of curvature larger than that of the loss adjusting bobbin 13, thereby performing the surplus length processing of the optical fiber. Since the radius of curvature of the surplus length processing bobbin 24 is sufficiently large, there is no loss due to winding. Therefore, the loss of the optical signal between the input connector 21 and the output connector 25 is {A + B × (the number of turns on the loss adjustment bobbin 23)} dB, and the number of turns for winding the optical fiber around the cylinder of the loss adjustment bobbin 13 is By increasing or decreasing the loss, it becomes possible to adjust the loss in units of BdB.

  Although the configuration of the embodiment has been described in detail above, there is a close relationship between the radius of curvature and bending loss of a single mode fiber. Generally, if the radius of curvature is 20 mm or more, the bending loss can be regarded as almost 0 dB, and the bending loss increases as the radius of curvature becomes smaller than 20 mm (reference: http://times.ansl.ntt. co.jp/gijyutu/2000_06/Topic_05/topic05_06.html2) Fig. 6). A single-mode fiber that allows a radius of curvature of up to 4 mm has also been commercialized (Reference: http://www.Furukawa.co.jp/fiber/jp/products/pdf/sm332-pf.pdf) If the radius is 4 mm or more, there is no problem with reliability. In this embodiment, although the loss occurs, the characteristics of the single mode fiber having a curvature radius of 4 to 20 mm, which has no problem in quality, are actively used.

  Next, a second embodiment of the present invention will be described. FIG. 3 shows a configuration diagram of a second embodiment of an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention. In the figure, an input connector 31 includes an optical component 32 having a loss of AdB, a loss fine adjustment bobbin 33a having a small curvature radius, a loss coarse adjustment bobbin 33b having a smaller curvature radius than the loss fine adjustment bobbin 33a, and a large curvature radius. An output connector 35 is wired by an optical fiber through a loss adjusting bobbin 34. The loss fine adjustment bobbin 33a and the loss coarse adjustment bobbin 33b constitute the bobbin 13 having a plurality of radii of curvature in FIG.

  It is assumed that the loss fine adjustment bobbin 33a attenuates the optical signal by 0.1 dB per winding by arranging the optical fiber. It is assumed that the radius of curvature of the loss coarse adjustment bobbin 33b is smaller than that of the loss fine adjustment bobbin 33a, and the optical signal is attenuated by 1.0 dB per turn when the optical fiber is wired.

  Thus, in this embodiment, rough adjustment and fine adjustment are possible by preparing two types of bobbins 33a and 33b having different curvature radii. For example, when the loss adjustment of 2.5 dB other than the loss of the optical component 32 is necessary, if the bobbin 23 adds 0.1 dB loss per winding in the configuration of the first embodiment shown in FIG. It is necessary to wind 25 times.

  On the other hand, in the configuration of the second embodiment of FIG. 3, a loss of 0.5 dB is obtained by winding the bobbin 33a five times, and a loss of 2.0 dB is obtained by winding the bobbin 33b twice. A loss adjustment of 2.5 dB can be achieved only by winding it seven times. As described above, in this embodiment, since two types of bobbins having different orders of increase loss are prepared, an effect of reducing the number of times the optical fiber is wound around the bobbin can be obtained.

  Next, a third embodiment of the present invention will be described. FIG. 4 shows a configuration diagram of a third embodiment of an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention. In the figure, an input connector 41 is wired to an output connector 45 by an optical fiber through an optical component 42 with a loss of AdB, a conical bobbin 43 for loss adjustment, and a loss adjustment bobbin 44 with a large curvature radius. Yes.

  Since the diameter of the conical bobbin 43 changes depending on the height, the optical fiber is wired in a portion that attenuates by 0.1 dB per winding and a portion that attenuates by 1.0 dB per winding, so that a simpler configuration can be used. The same effect as in the second embodiment can be obtained. Further, the loss can be finely adjusted by shifting the winding position up and down. The conical bobbin 43 constitutes the bobbin 13 having a plurality of radii of curvature shown in FIG.

  Next, a fourth embodiment of the present invention will be described. FIG. 5 shows a configuration diagram of a fourth embodiment of an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention. In the figure, an input connector 51 is wired to an output connector 55 via an optical component 52 with a loss of AdB, a loss adjustment bobbin 53 with a variable curvature radius, and a surplus length processing bobbin 54 with a large curvature radius. . The loss adjusting bobbin 53 having a variable curvature radius constitutes the bobbin 13 having a plurality of curvature radii shown in FIG.

  In this embodiment, the loss per turn can be changed by changing the radius of curvature of the loss adjusting bobbin 53. If the input / output loss is measured and does not fall within the standard after the optical fiber is wound, the number of turns of the optical fiber is changed by changing the radius of the loss adjusting bobbin 53 while the optical fiber is wound. Loss can be adjusted without

  Next, a fifth embodiment of the present invention will be described. FIG. 6 shows a configuration diagram of a fifth embodiment of an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention. In the figure, an input connector 61 is wired to an output connector 65 through an optical component 62 with a loss of AdB, a small box 63 that can be wired inside, and a surplus length processing bobbin 64 with a large curvature radius. Here, by arranging the optical fiber within a narrow range of the inside of the box 63, a bending loss is generated as a result. The present invention makes it possible to freely adjust the loss by utilizing the bending loss of the optical fiber. Instead of the loss adjusting bobbin, the fifth embodiment shown in FIG. 6 has a configuration in which bending loss occurs by using the box 63.

  Next, a sixth embodiment of the present invention will be described. FIG. 7 shows a configuration diagram of a sixth embodiment of an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention. In this embodiment, instead of the loss adjustment bobbins 23, 33a, 33b, 53 of the above embodiment, a configuration in which bending loss is generated by the tube 73 shown in FIG. In FIG. 7, an input connector 71 has a configuration in which an optical fiber is routed to an output connector 75 through an optical component 72 with a loss of AdB, a hollow flexible tube 73, and a surplus length processing bobbin 74 with a large curvature radius. It is. The tube 73 constitutes the bobbin 13 having a plurality of radii of curvature shown in FIG.

  In this embodiment, the optical fiber is laid so as to penetrate into the tube 73 and then the tube 73 is bent, so that the radius of curvature is locally reduced and bending loss is caused to adjust the loss. In this embodiment, since the loss can be freely adjusted by increasing the loss by bending the tube 73 after passing the optical fiber through the tube 73, the loss can be achieved without knowing the fiber fusion know-how. Adjustment work is possible, and loss adjustment work is easy. Even when readjustment is necessary, the amount of loss can be adjusted by increasing or decreasing the number of turns around which the optical fiber is wound around the tube 73.

  In addition, according to the present embodiment, since it is only necessary to wire the optical fiber to the tube 73, an expensive fusion machine is not required, and the cost can be reduced. Conventionally, when adjusting the loss, it has been necessary to use an expensive optical fiber fusion machine having an increased loss connection function and perform the optical fiber fusion, but the optical fiber fusion can be made unnecessary.

  Next, the main part of the fourth embodiment of the present invention will be described. FIG. 8 is a configuration diagram of the main part of a fourth embodiment of an optical transmission apparatus having an optical fiber loss adjustment function according to the present invention. In this embodiment, an example of the structure of the loss adjusting bobbin 53 having a variable curvature radius shown in FIG. 5 is shown. As shown in the front view of FIG. 8D, a short side of a rectangular flexible leaf spring 82 is fixed to a part of the axial direction of a shaft 81 with a cylindrical spring. In this state, when the shaft 81 is manually turned clockwise to some extent, as shown in the perspective view of FIG. 8A, the loss adjusting bobbin 53 around which the leaf spring 82 is wound is formed.

  Further, when the shaft 81 is manually rotated counterclockwise in this state, the leaf spring is loosened as indicated by 82a, and the radius of curvature increases. On the other hand, when the shaft 81 is manually rotated clockwise from the state shown in FIG. 8A, the leaf spring is wound and squeezed as shown by 82b, and the radius of curvature of the cylinder decreases. In this way, the radius of curvature of the loss adjustment bobbin 53 can be varied.

  The present invention is not limited to the above embodiment. For example, in FIG. 3, one loss fine adjustment bobbin and one loss coarse adjustment bobbin are provided. You may make it provide one by one. Further, the connection order between the input connector and the output connector is not limited to that shown in FIGS.

It is a principle block diagram of this invention. It is a block diagram of 1st embodiment of this invention. It is a block diagram using the loss adjustment bobbin which is 2nd embodiment of this invention. It is a block diagram which used the cone instead of the bobbin which is 3rd embodiment of this invention. It is a block diagram using the loss-adjusting bobbin with a variable curvature radius which is the 4th embodiment of this invention. It is a block diagram which used the box for loss adjustment which is the 5th embodiment of this invention. It is a block diagram which used the tube for loss adjustment which is the 6th embodiment of this invention. It is a figure which shows an example of the structure of the loss adjustment bobbin of a curvature radius variable of FIG.

Explanation of symbols

11, 21, 31, 41, 51, 61, 71 Input connector 12, 22, 32, 42, 52, 62, 72 Optical component 13 Bobbins with multiple radii of curvature for loss adjustment 14, 24, 34, 44, 54, 64, 74 Extra length processing bobbins 15, 25, 35, 45, 55, 65, 75 Output connector 23 Loss adjustment bobbin 33a Loss fine adjustment bobbin 33b Loss coarse adjustment bobbin 43 Loss adjustment conical bobbin 53 Loss adjustment bobbin with variable curvature radius 63 Small box that can be wired inside 73 Hollow flexible tube 81 Shaft (attached to mainspring)
82, 82a, 82b leaf spring

Claims (3)

An optical transmission device having an optical fiber loss adjustment function of an optical transmission system for transmitting an optical signal by an optical fiber from an input connector to an output connector through an optical component and an optical loss adjustment bobbin,
An optical transmission having an optical fiber loss adjustment function, wherein the bobbin for optical loss adjustment is provided with one bobbin having a weight shape having different curvature radii at circumferential positions where the optical fiber is wound around the outer peripheral side surface. apparatus. An optical transmission device having an optical fiber loss adjustment function of an optical transmission system for transmitting an optical signal by an optical fiber from an input connector to an output connector through an optical component and an optical loss adjustment bobbin,
The light loss adjusting bobbin includes a cylindrical shaft with a spring and a leaf spring having a rectangular outer shape with one side fixed to a part of the outer periphery of the shaft. a cylindrical winding the plate spring to the shaft, by varying the radius of curvature by varying the rotational direction and the rotational number of the shaft, the loss adjustment of the optical fiber wound around the outer peripheral surface of the leaf spring the optical transmission device including an optical fiber loss adjustment function and performs. An optical transmission device having an optical fiber loss adjustment function of an optical transmission system for transmitting an optical signal by an optical fiber from an input connector to an output connector through an optical component and an optical loss adjustment unit,
  The optical loss adjustment unit is a box-shaped component in which the optical fiber is wired, and has an optical fiber loss adjustment function that performs a loss adjustment by generating a bending loss in the optical fiber. Optical transmission equipment.

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