JP4062110B2 - OPTICAL CONNECTION COMPONENT, OPTICAL CONNECTION METHOD, AND OPTICAL COMMUNICATION DEVICE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical connection component, a connection method, and an optical communication device for connecting optical fibers having different mode field diameters.
[0002]
[Prior art]
In optical communication using optical fibers, the introduction of WDM (wavelength multiplexing) optical transmission has progressed as the amount of information and communication lines has increased, and DWDM optical transmission is multiplexed at a high density that enables high-capacity transmission. Is also being considered. For this reason, the optical fiber used for the optical wiring in the optical communication device is required to bend with a small diameter in order to increase the storage density. In addition, as the number of communication lines increases, a large number of optical fibers are congested. Therefore, it is required to use optical fibers that can suppress the increase in loss in handling from a wiring rack in a cabinet, especially handling in a live state. ing.
[0003]
As an optical fiber capable of meeting such demands, a bending-resistant optical fiber capable of suppressing a bending loss to 1.0 dB or less even when the bending radius is bent at about 15 mm has been developed. However, since such an optical fiber has a mode field diameter as small as 8 μm or less, an increase in loss due to a difference in mode field diameter occurs when connected to a normal single mode optical fiber.
[0004]
Conventionally, when optical fibers having different mode field diameters (hereinafter referred to as MFDs) are connected to each other, an intermediate optical fiber having an intermediate value of MFD of both optical fibers is connected to suppress an increase in loss. It is known (see, for example, Patent Document 1). FIG. 10 is a diagram showing the contents disclosed in Patent Document 1, in which C is an optical fiber cable, P is an optical waveguide, 1 and 2 are optical fibers, 1a and 2a are core portions, and 1b and 2b are cladding portions. Reference numeral 3 is a reinforcing tube (or ferrule), 4 is an adhesive, 5, 6 and 7 are intermediate optical fibers, and 5a, 6a and 7a are core parts.
[0005]
FIG. 10 shows a case where an optical fiber cable C and an optical waveguide P having different MFDs are connected, and the optical fiber cable C is exposed at the inner end of the optical fiber 1 by removing the coating at the tip. The optical fiber 1 includes a core part 1a and a clad part 1b, and the MFD of the core part 1a is, for example, 10 μm. The optical fiber 2 on the optical waveguide P side includes a core part 2a and a clad part 2b, and the MFD of the core part 2a is, for example, 5 μm.
[0006]
The difference in MFD between the optical fiber 1 and the optical fiber 2 is 5 μm, and in the case of direct connection, the connection loss is theoretically 1.94 dB. This connection loss increases as the difference in MFD increases. In FIG. 10, intermediate optical fibers 5, 6, and 7 having an MFD intermediate value between the optical fibers 1 and 2 are interposed between the optical fibers 1 and 2, and the optical fiber 1 is stepwise. The MFD is brought close to the MFD of the optical fiber 2.
[0007]
The intermediate optical fibers 5, 6, and 7 have, for example, the same outer diameter as that of the optical fiber 1 and the MFDs of the core portions 5 a, 6 a, and 7 a are 8 μm, 7 μm, and 6 μm. As a connection procedure, first, the intermediate optical fiber 5 is spliced to the end portion of the optical fiber 1 and cut about 10 mm, and the intermediate optical fiber 6 is spliced to that portion. Similarly, the intermediate optical fiber 7 is spliced to the intermediate optical fiber 6. A reinforcing tube 3 made of stainless steel, ceramic, or the like is attached to the surfaces of the optical fiber 1 and the intermediate optical fibers 5, 6, 7 by an adhesive 4 to give the optical fiber strength.
[0008]
With the above configuration, the connection loss between the optical fiber 1 and the intermediate optical fiber 5 is 0.21 dB, the connection loss between the intermediate optical fibers 5 and 6 is 0.08 dB, and the connection between the intermediate optical fibers 6 and 7 is performed. The loss is 0.10 dB, and 0.14 dB between the intermediate optical fiber 7 and the optical fiber 2. The total connection loss is 0.53 dB, and the connection loss based on the difference in MFD can be greatly reduced as compared with the connection loss of 1.94 dB when the optical fiber 1 and the optical fiber 2 are directly connected.
[0009]
In addition, FIG. 11 shows that when optical fibers having different MFDs are directly connected by a mechanical splice, the MFD having a smaller MFD is partially enlarged by heat treatment and matched to the optical fiber having a larger MFD. It is a figure which shows the example (for example, refer patent document 2) made to do. In the figure, 11 and 12 are optical fibers, 11a and 12a are core parts, 11b and 12b are clad parts, 13 is a fiber coating, 14 is a ferrule, and 15 is a split sleeve.
[0010]
In FIG. 11, the MFD of the core portion 11a at the connection end of the optical fiber 11 having the smaller MFD (expressed as the core diameter in Patent Document 2) is locally heated by a burner or the like, and the dopant of the core portion 11a is changed. Thermal diffusion is performed on the clad portion 11b side. Due to this thermal diffusion, the MFD of the connecting end portion of the optical fiber 11 is partially expanded so that it approaches the MFD of the core portion 12a of the other optical fiber 12 (Thermally-diffused Expanded Core, hereinafter referred to as TEC). it can.
[0011]
As this TEC method, the fiber coating 13 in the middle portion of the optical fiber 11 having the smaller MFD is removed, and the optical fiber 11 itself is not melted, but at a temperature at which the dopant of the core portion 11a diffuses to the cladding portion 11b side. Heat up. A central portion of the TEC portion 11c where the MFD is enlarged is cut by stress rupture to form a connection end surface. The connection ends of the optical fiber 11 and the optical fiber 12 are housed in a ferrule 14 and bonded and integrated, and then butt-connected by a mechanical splice using a split sleeve 15 or the like.
[0012]
In addition, by connecting the optical fiber subjected to the TEC treatment as an intermediate optical fiber between the optical waveguides and optical fibers having different MFDs, an increase in connection loss due to different MFDs is suppressed. The configuration is also known (see, for example, Patent Document 3). As described above, by using an intermediate optical fiber to butt-connect optical fibers having different MFDs, the difference in MFD at the connection portion can be reduced, and an increase in connection loss can be suppressed. It is also known that by increasing the MFD at the connection end, it is possible to reduce the increase in loss due to the shaft misalignment during connection.
[0013]
[Patent Document 1]
JP-A-6-43332
[Patent Document 2]
Japanese Patent No. 2619130
[Patent Document 3]
JP 2000-275470 A
[0014]
[Problems to be solved by the invention]
When the MFDs of the optical fibers connected to each other are different, as shown in FIG. 10 described above, a plurality of optical fibers having intermediate MFD values of the MFDs of both optical fibers are connected to reduce the MFD difference step by step. Can do. However, if a plurality of intermediate optical fibers are connected in sequence and the MFD is adjusted stepwise, the axial length of the optical connector increases when the intermediate optical fiber is housed in the optical connector as a built-in optical fiber. Becomes longer. Moreover, since it is necessary to connect and form short optical fibers sequentially by fusion, the manufacturing cost increases, which is not realistic.
[0015]
Further, as shown in FIG. 11, the connection end side of the optical cable having the smaller MFD is TEC-processed to enlarge the MFD, and the TEC-processed intermediate optical fiber is used, so that the difference in MFD is caused. It is useful to suppress the loss increase. However, there is a problem in terms of work and cost in connecting the connection end of the optical cable by TEC processing. In particular, it is not efficient to perform TEC treatment or end face polishing on an optical fiber at the site or assembly site because workability is not good.
[0016]
Optical communication equipment and external connections using optical fiber, optical communication equipment using optical fiber, and internal wiring, etc., can be detachably connected using optical connectors instead of directly connecting optical fibers due to operational problems. Many. In connection with an optical connector, one optical connector is configured as a female type and the other as a male type, and both optical connectors are directly coupled to each other, and both optical connectors having the same shape are connected via a connection adapter. There is a form. Furthermore, the connection of the optical cable includes various connection forms such as using an optical cable prepared locally, or using an optical cable and an optical connector used in existing facilities as they are.
[0017]
Although FIG. 10 or FIG. 11 discloses a configuration for suppressing an increase in connection loss by using an intermediate optical fiber or TEC process for connecting optical fibers having different MFDs, a specific example that can be attached and detached using an optical connector is disclosed. The connection structure is not clear. For this reason, it is necessary to individually cope with various connection forms of the optical fiber, which is not practical.
[0018]
The present invention has been made in view of the above-described circumstances, and can suppress various increases in connection loss using an intermediate optical fiber for connecting optical fibers having different MFDs. It is an object of the present invention to provide an optical connection component, an optical connection method, and an optical communication device that are excellent in workability at a work site and are inexpensive.
[0019]
[Means for Solving the Problems]
An optical connection component according to the present invention is an optical connection component for detachably connecting optical fibers having different mode field diameters with an optical connector, and both optical connectors in the connection housing of the optical connection component. end A mode field diameter conversion member having a connection end face A split sleeve that fits the ferrule of the optical connector is placed on each side of the mode field diameter conversion member. It is characterized by that. Further, the mode field diameter conversion member is formed of a single short optical fiber having a mode field diameter intermediate between different mode field diameters of the optical fibers to be connected, or connected at the connection end face side. It is formed of a short optical fiber that has been heat-treated so as to have a mode field diameter that is the same as or close to the mode field diameter of each optical fiber.
[0020]
The optical connection method according to the present invention is an optical connection method in which optical fibers having different mode field diameters are detachably connected to each other by an optical connector. end A mode field diameter conversion member having a connection end face is housed in Arrange the split sleeves on which the ferrules of the optical connector are fitted on both sides of the mode field diameter conversion member, Optical fibers having different mode field diameters are connected to each other through a mode field diameter conversion member.
[0021]
The optical communication device according to the present invention has an optical fiber wiring portion, an optical fiber having a mode field diameter of 8 μm or less is used for the optical wiring inside the device housing, and the optical wiring outside the device housing is used. The mode field diameter is larger than the optical fiber used for the optical wiring in the device casing. A communication device using an optical fiber, comprising: an optical connection member that optically connects an optical fiber inside the device casing and an optical fiber outside the device casing by an optical connector; Have connection end faces at both ends in the connection housing The mode field diameter conversion member is stored. The split sleeves on which the ferrules of the optical connector are fitted are arranged on both sides of the mode field diameter conversion member. It is characterized by.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
According to the figure , Outline of connection mode between optical fibers having different mode field diameters according to the present invention Will be explained. FIG. 1A and FIG. Connection FIG. 2 is a diagram for explaining the form. Connection It is a figure explaining a form. In the figure, 20 and 22 are optical connectors, 21 is an optical connection component, 23 is a first optical fiber, 24 is a mode field diameter conversion member, 24a and 24b are end faces, 25 is a second optical fiber, 26 is a ferrule, 27 is a ferrule holding member, 28, 28a and 28b are connecting housings, 29 is a sleeve, 30 and 31 are intermediate optical fibers, 30a and 31a are core parts, and 30b and 31b are clad parts.
[0023]
In the figure, an optical connector 20 and an optical connector 22 are attached to connection ends of optical cables (or optical cords) C1 and C2, respectively, and are optically interconnected via an optical connection component 21. The optical cable C1 or C2 has a single or multi-core first optical fiber 23 or second optical fiber 25 accommodated therein, and the optical coating 20 or the optical connector is removed by removing the fiber coating of each connection end. 22 is attached. Although optical connectors 20 and 22 have various configurations depending on the connection form, in order to simplify the description, a ferrule 26 for positioning and fixing the optical fiber and a ferrule holding member 27 for holding the ferrule are shown in the figure. It is shown in the simplest form consisting of The optical connectors 20 and 22 will be described as being formed in the same shape.
[0024]
As shown in FIG. 1A, the optical connection component 21 is configured by housing a mode field diameter conversion member 24 in a single cylindrical connection housing 28. Further, as shown in FIG. 1B, the mode field diameter conversion member 24 can be accommodated in cylindrical connection housings 28a and 28b divided into two parts. The mode field diameter converting member 24 is formed by covering the outer peripheral surface of the intermediate optical fiber 30 or 31 with a sleeve 29 formed of resin or ceramic. The intermediate optical fibers 30 and 31 are formed of a short optical fiber composed of core portions 30a and 31a and clad portions 30b and 31b. Both end surfaces 24a and 24b of the intermediate optical fibers 30 and 31 are end-polished so as to coincide with the sleeve 29. It is housed in a state where it can be fixed or moved somewhat in the axial direction in the central part.
[0025]
By fitting the optical connector 20 and the optical connector 22 on both sides of the optical connection component 21, the first optical fiber 23 and the second optical fiber 25 are optically connected via the intermediate optical fiber 30 or 31. . The optical connection component 21 corresponds to a connection component generally referred to as a connection adapter that connects optical connectors on both sides to each other, but in the present invention, short optical fibers 30 and 31 are provided. This is different from the conventional connection adapter.
[0026]
The first embodiment of FIG. 1 is a mode field diameter conversion member housed in the optical connection component 21 when the MFD of the first optical fiber 23 of the optical cable C1 and the second optical fiber 25 of the optical cable C2 are different. 24 intermediate optical fibers 30 are defined. The intermediate optical fiber 30 in FIG. 1 has an optical fiber in which the mode field diameter (hereinafter referred to as MFD) of the core portion 30a has an intermediate value between the MFDs of the first optical fiber 23 and the second optical fiber 25 connected to each other. Is used.
[0027]
For example, it is assumed that the MFD of the first optical fiber 23 to which the optical connector 20 is attached is 9.2 μm, and the MFD of the second optical fiber 25 to which the optical connector 22 is attached is 6.3 μm. In this case, the MFD of the intermediate optical fiber 30 of the mode field diameter converting member 24 is formed of a single short optical fiber having an MFD between 6.3 μm and 9.2 μm, for example, an MFD of 7 μm or 8 μm. As a result, the MFD difference between the connection end faces of the optical fibers 23 or 25 and the intermediate optical fiber 30 can be reduced.
[0028]
2nd in FIG. Connection When the MFDs of the first optical fiber 23 of the optical cable C1 and the second optical fiber 25 of the optical cable C2 are different from each other, the intermediate optical fiber 31 of the mode field diameter conversion member 24 accommodated in the optical connection component 21 is used. It prescribes. In the intermediate optical fiber 31 of FIG. 2, the MFD of the core part 31a is the same as or close to the smaller MFD value of the first optical fiber 23 and the second optical fiber 25 connected to each other. The optical fiber which has is used. As another example, an optical fiber in which two types of optical fibers that are the same as or close to the MFDs of both of the optical fibers 23 and 25 are fusion-connected is used.
[0029]
The MFD of the intermediate optical fiber 31 has the same value as or close to the MFD of the first optical fiber 23 of the optical connector 20 on the one end face 24a side, and the second optical fiber of the optical connector 22 on the other end face 24b side. The value is the same as or close to 25 MFD. For example, it is assumed that the MFD of the first optical fiber 23 to which the optical connector 20 is attached is 9.2 μm, and the MFD of the second optical fiber 25 to which the optical connector 22 is attached is 6.3 μm. In this case, the MFD at one end (the connection side of the optical connector 20) of the intermediate optical fiber 31 of the mode field diameter conversion member 24 is 9.2 to 10.0 μm, and the other end (the connection side of the optical connector 22). ) Is set to 6.3 to 7.0 μm. As a result, the MFD difference between the connection end faces of the respective optical fibers 23 or 25 and the intermediate optical fiber 31 can be reduced to zero or small.
[0030]
3 and 4 are the same as FIG. Connection It is a figure explaining the specific example of the intermediate optical fiber in a form, and its manufacture example. In the figure, 32 and 33 are optical fibers, 32a and 33a are core parts, 32b and 33b are clad parts, 32c is an MFD expansion part, 34 is a cutting part, and 35 is a fusion splicing part. Description of other reference numerals is omitted by using the same reference numerals as those used in FIGS.
[0031]
FIG. 3 shows a mode field diameter converting member 24 using an optical fiber 32 having an MFD that is the same as or close to that of the optical fiber having a smaller MHD (for example, the second optical fiber 25) in FIG. 2 as an intermediate optical fiber. This is a manufacturing example. In FIG. 3 (A), the optical fiber 32 removes the fiber coating of the middle part or end part of the optical fiber which consists of the core part 32a and the clad part 32b, and exposes a glass fiber part. Next, as shown in FIG. 3B, the part from which the fiber coating has been removed is subjected to TEC heating by a heating means such as a burner, and the dopant of the core part 32a is thermally diffused to the cladding part 32b side. The MFD enlarged portion 32c enlarged in a taper shape in the longitudinal direction is formed.
[0032]
Thereafter, as shown in FIG. 3C, cutting is performed at the center portion of the MFD enlarged portion 32 c, and the maximum MFD of the MFD enlarged portion 32 c is exposed at the end face of the cut portion 34. Next, as shown in FIG. 3D, the cutting portion 34 is inserted into the sleeve 29 so that the cut end surfaces thereof coincide with each other and fixed by adhesion or the like, and the sleeve 29 and the optical fiber 32 are integrated. Further, at this stage, the cut portion 34 is end-polished together with the sleeve 29 to form the end surface 24a. Thereafter, as shown in FIG. 3 (E), the optical fiber 32 is cut along the opposite end portion of the sleeve 29, and the cut portion is then end-polished to form an end face 24b. The diameter conversion member 24 is used.
[0033]
4 is used as an intermediate optical fiber by fusion splicing two types of optical fibers 32 and 33 that are the same as or close to the MFD of both the first optical fiber 23 and the second optical fiber 25 in FIG. This is a manufacturing example of the mode field diameter conversion member 24. In FIG. 4A, optical fibers 32 and 33 are fusion-spliced by removing the fiber coating from the end portion of the optical fiber made up of core portions 32a and 33a and cladding portion 32b33b and butting the end faces. The optical fiber 32 is an optical fiber similar to the optical fiber having a smaller MFD (for example, the second optical fiber 25), and the optical fiber 33 has an optical fiber having a larger MFD (for example, the first optical fiber). The same optical fiber as the first optical fiber 23) can be used.
[0034]
Next, as shown in FIG. 4B, the TEC heating is performed in the vicinity of the fusion splicing part 35 by a heating means such as a burner, and the dopant of the core part 32a is thermally diffused toward the clad part 32b to make it small. The larger MFD is enlarged in a taper shape in the longitudinal direction so as to coincide with the larger MFD. Although the larger MFD for heating is somewhat enlarged, the amount of enlargement is small and the difference in MFD at the fusion splicing portion can be substantially eliminated.
[0035]
Thereafter, as shown in FIG. 4C, one optical fiber 33 is cut in the vicinity of the fusion splicing portion 35 (the optical fiber 32 side may be cut). Next, as shown in FIG. 4D, the cutting portion 34 is inserted into the sleeve 29 so that the cut end faces thereof are aligned, and fixed by adhesion or the like, and the sleeve 29 and the optical fibers 32 and 33 are integrated. Further, at this stage, the cut portion 34 is end-polished together with the sleeve 29 to form the end surface 24a. Thereafter, as shown in FIG. 4 (E), the optical fiber 32 is cut along the opposite end of the sleeve 29, and then the cut end is polished to form an end face 24b. The diameter conversion member 24 is used.
[0036]
Next, loss reduction in connection between optical fibers having different MFDs will be described with reference to FIGS. FIG. 5 is a diagram illustrating a relationship between a connection loss (mismatch loss) due to a difference in MFD and a difference in MFD when connecting optical fibers having different MFDs. In FIG. 5, when the MFD of one optical fiber L is 9.2 μm, the mismatch loss is shown when the MFD of the optical fiber S connected thereto is changed. According to this figure, the MFD of the connecting optical fiber S is 7.4 μm and 0.2 dB, the MFD is 0.6 dB when the MFD is 5.65 μm, and 1.0 dB when the MFD is 5.65 μm, and the difference in MFD increases. This shows that the mismatch loss also increases.
[0037]
FIG. 6 shows the total mismatch loss and intermediate light at two locations on both sides of the intermediate optical fiber M when the intermediate optical fiber M is connected between two optical fibers L and S having different MFDs. It is a figure which shows the relationship with MFD of the fiber M. FIG. FIG. 6A shows a case where the right optical fiber L has an MFD of 9.2 μm and the left optical fiber S has an MFD of 6.3 μm. FIG. 6B shows a case where the right optical fiber L has an MFD of 9.2 μm and the left optical fiber S has an MFD of 7.5 μm.
[0038]
As shown in FIG. 5, for example, when an optical fiber L having an MFD of 9.2 μm and an optical fiber S having an MFD of 6.3 μm are directly connected, a mismatch loss of 0.6 dB occurs at the connection portion. As shown in (A), between the optical fibers L and S, for example, by connecting an intermediate optical fiber M having an MFD in the range of 6.8 μm to 8.5 μm, the number of connection points increases to two. The total mismatch loss of the two locations can be 0.4 dB or less.
[0039]
As shown in FIG. 5, when an optical fiber L having an MFD of 9.2 μm and an optical fiber S having an MFD of 7.5 μm are directly connected, a mismatch loss of 0.18 dB occurs at the connection portion. As shown in (B), the number of connection points is increased to two by interposing an intermediate optical fiber M having an MFD in the range of 8.0 μm to 8.7 μm between the optical fibers L and S, for example. The total mismatch loss at the two locations can be 0.12 dB or less.
[0040]
As described above, the mismatch loss is obtained by interposing the single intermediate optical fiber M having the intermediate MFD value between the optical fibers L and S in the connection between the optical fiber L and the optical fiber S having different MFDs. Can be suppressed. Therefore, on the assumption of FIG. 6, for example, the first of FIG. Connection In the embodiment, the first optical fiber 23 can be configured as the optical fiber L, the second optical fiber 25 can be configured as the optical fiber S, and the intermediate optical fiber 30 accommodated in the mode field diameter conversion member 24 can be configured as the intermediate optical fiber M. . With this configuration, the mismatch loss cannot be completely eliminated by connecting the cables C1 and C2 having different MFDs, but the mismatch loss can be reliably reduced.
[0041]
In FIG. 1 above Connection The configuration is such that a single short intermediate optical fiber having an MFD between the MFD values of the first optical fiber 23 and the second optical fiber 25 is housed and held in the optical connection component 21. Therefore, it can be manufactured at a very low cost. The optical connectors 20 and 22 can be existing general-purpose products, and can be connected to an optical connector attached to an existing optical cable.
[0042]
2nd in FIG. Connection In the embodiment, as in the case of FIG. 1, the first optical fiber 23 is an optical fiber L, the second optical fiber 25 is an optical fiber S, and the intermediate optical fiber 31 accommodated in the mode field diameter conversion member 24 is an intermediate. It can be configured as an optical fiber M. The intermediate optical fiber 31 in FIG. 2 can be completely matched with the MFD of the first optical fiber 23 and the MFD of the second optical fiber 25. For this reason, the mismatch loss due to the difference in MFD It is also possible to make it zero. However, since the TEC heating process as shown in FIGS. 3 and 4 is added to the formation of the intermediate optical fiber 31, the cost is somewhat higher than that of the configuration of FIG.
[0043]
Of FIG. Connection Also in the form, it is structurally the same as in FIG. 1, and the optical connectors 20 and 22 connected to the optical connection component 21 can both use existing general-purpose products and are attached to existing optical cables. It can also be connected to existing optical connectors. However, if the MFDs of the optical cables C1 and C2 connected via the optical connection component 21 can be assumed in advance, it is preferable to have the same configuration as much as possible from the viewpoint of production management. Can have versatility.
[0044]
In optical wiring inside and outside equipment using optical fibers, one of the optical cables connected to each other is often a normal single mode optical fiber suitable for long-distance optical transmission. Therefore, on the premise that a normal single mode optical fiber is connected to one of the mode field diameter conversion members 24 of the optical connection component, the MFD center value of the normal single mode optical fiber is set to about ± 10%. desirable. In this case, when the MFD center value is 9.5 μm, the MFD is set to about 8.5 to 10.5 μm. Further, the other optical cable is required to use an optical fiber that can be bent with a small diameter and can be made compact in the apparatus wiring, or has a characteristic that a loss variation during handling in a congested state or an access system is small.
[0045]
The latter In-device wiring As an optical fiber, for example, the MFD according to the definition of Petermann-I at a wavelength of 1.55 μm is 8 μm or less, and the absolute values of chromatic dispersion at a wavelength of 1.3 μm and a wavelength of 1.55 μm are both 12 ps / nm. Recently, an optical fiber having a cable cutoff wavelength of 1.26 μm or less and an MFD of 6 μm or more as defined by Peterman-I at a wavelength of 1.3 μm has been developed. On the other hand, as described above, the optical fiber outside the device has a larger mode field diameter than the optical fiber used for the optical wiring inside the device. An optical fiber is used.
[0046]
The optical fiber cable using the optical fiber core has an advantage that the wiring work can be performed safely and easily because a loss increase of 1.0 dB or more does not occur even when bent at a bending radius of about 15 mm. It is. Therefore, one side of the mode field diameter conversion member 24 of the optical connection component 21 may be formed so that the MFD is 8 μm or less on the assumption that such an optical fiber is connected. Moreover, since the increase in loss can be suppressed considerably by setting the MFD difference between the connected optical fibers to be within ± 10%, the MFD difference with the optical fiber connected in advance is within this range (± 10%). It is desirable to keep
[0047]
FIG. 7 is a diagram showing an example of an optical communication device using the optical connecting component according to the present invention. In the figure, 40 is an optical communication device, 41 is a device housing, 42 is a planar optical waveguide, 43 and 44 are optical fiber arrays, 45 is a multi-core optical fiber cord, and other symbols are shown in FIGS. The description is omitted by using the used codes.
[0048]
For example, as shown in FIG. 7, the optical communication device 40 includes an optical component such as a planar optical waveguide 42 in a device casing 41, and is connected to an external optical transmission line via an optical wiring in the device. To do. An optical connection component 21 containing a mode field diameter conversion member 24 is attached to the device casing 41, and an optical cord (or optical cable) C1 for an external transmission path and an optical cord (or optical cable) C2 in the device are optically transmitted. Configured to connect. In the optical connection, the optical connector 20 attached to the optical cord C1 and the optical connector 22 attached to the optical cord C2 are connected via the optical connecting component 21 in the same manner as described with reference to FIGS.
[0049]
In the optical communication device 40, for example, a multi-core optical fiber cord 45 with a branching portion is connected to the planar optical waveguide 42 using an optical fiber array 43, and further connected to the optical cord C 2 and optically connected by the optical connector 22. Connected to the component 21. In addition, the optical cord C2 may be directly connected to the planar optical waveguide 42 using the optical fiber array 44. For the optical cord C2 used for the optical wiring in the device casing 41, for example, it is desirable to use an optical fiber capable of bending a small diameter with a bending radius of 30 mm or less, preferably 15 mm or less. By using an optical fiber that can be bent with a small diameter, the optical wiring space can be reduced, and the optical communication device can be miniaturized.
[0050]
If an optical fiber that can be bent at a small diameter is used for the optical cord C2 used for the wiring inside the device casing 41, the MFD becomes small, and the consistency with the MFD of the optical cord C1 used for the transmission path outside the device decreases. However, by using the optical connection component 21 containing the mode field diameter conversion member 24 for the optical connection between the inside and the outside of the device casing 41, the consistency of the optical codes C1 and C2 due to the different MFD is improved, and the loss The increase can be suppressed.
[0051]
FIG. 8 is a diagram showing a specific example of the optical connecting component and the optical connecting method of the present invention. In the figure, 50 and 52 are optical connectors, 51 is an optical connection component, 53 is a ferrule, 54 is a ferrule holding member, 55 is an optical connector housing, 56 is a spring, 57 is a boot, 58 is a mode field diameter converting member, 59 Is an optical connection component housing, 60 is an optical connector engaging member, 61 is a split sleeve, and 62 is a sleeve fixing member.
[0052]
The optical connector 50 and the optical connector 52 can have the same shape, and may be general-purpose products that are generally used. These optical connectors are configured by housing a ferrule 53 for positioning and fixing an optical fiber and a ferrule holding member 54 for holding the optical fiber in an optical connector housing 55. By urging the ferrule holding member 54 into the optical connector housing 55 with a spring 56, the ferrule 53 is held and fixed so as to allow some movement in the axial direction. A boot 57 is attached to the rear portion of the optical connector housing 55 to protect and reinforce the lead portions of the optical cords (or optical cables) C1 and C2.
[0053]
As described with reference to FIGS. 1 and 2, the optical connection component 51 is configured by accommodating the mode field diameter conversion member 58 therein. The mode field diameter converting member 58 is On each side Split sleeve 61 Is arranged, It is housed in the optical connection component housing 59 via the sleeve fixing member 62. The ferrule 53 of the optical connectors 50 and 52 is positioned and held in the split sleeve 61. Further, optical connector engaging members 60 are arranged on both sides of the split sleeve 61, and are configured to engage and hold the connection with the optical connectors 50 and 52. The mode field diameter conversion member 58 is held in the approximate center of the optical connection component casing 59, but may be held in a float state that is slightly movable in the axial direction. By holding the mode field diameter converting member 58 in the float state, it is possible to mitigate axial position shifts at the joint surfaces when the optical connectors 50 and 52 are engaged.
[0054]
FIG. 9 is a diagram showing another specific example of the optical connecting component and the optical connecting method of the present invention. In the figure, 63 is an optical connection part, 64 is a connection adapter, 65 is a mode field diameter conversion member, 66 is an optical connection part case, 67 is an optical connector engaging member, 68 is a split sleeve, 69 is a connection adapter case, Reference numeral 70 denotes an optical connector engaging member, and 71 denotes a split sleeve. Description of other reference numerals is omitted by using the same reference numerals as in FIG.
[0055]
In the example of FIG. 9, it is possible to improve the matching of the optical cords C1 and C2 having different MFDs and suppress an increase in loss by simply adding the optical connection component 63 without changing the existing connection form at all. It is what. In the figure, optical connectors 50 and 52 are exactly the same as described in FIG. 8, and are attached to optical cords C1 and C2, respectively. Therefore, detailed description is omitted.
[0056]
In FIG. 9, the optical connectors 50 and 52 are optically connected via the optical connection component 63 and the connection adapter 64. The connection adapter 64 includes a pair of optical connector engagement members 70 in a connection adapter housing 69 and a split sleeve 71 held by the optical connector engagement member 70, and is a general-purpose product for interconnecting a pair of optical connectors. Is known as. That is, when the optical connection component 63 is not used, the optical connectors 50 and 52 can be directly connected.
[0057]
The optical connection component 63 is configured such that one end side of the optical connection component housing 66 has the same shape as the optical connector housing 55 (see FIG. 8), and a mode field diameter conversion member 65 is accommodated in this portion. . An optical connector engaging member 67 is provided on the other end side so that the optical connector 50 is connected. The mode field diameter changing member 65 is held by a split sleeve 68 and is accommodated so as to be somewhat movable in the axial direction. In this configuration, for example, the optical connection component 63 is connected and integrated with one of the existing connection adapters 64. Next, the optical connector 52 is connected to the other end of the connection adapter 64, and the optical connector 50 is connected to the optical connection component 63. Thus, the optical cord C1 and the optical cord C2 are optically connected via the mode field diameter converting member 65 housed in the optical connecting component 63.
[0058]
8 and 9, when the optical code C1 and the optical code C2 have different MFDs, the MFD of the intermediate optical fiber of the mode field diameter conversion member 65 is appropriately selected as described with reference to FIGS. By doing so, an increase in loss based on the difference in MFD can be suppressed. Further, by using the optical connecting component 21 as described above, the existing optical cords C1 and C2 and optical connectors 50 and 52 may be used as they are, or may be used by replacing them with ordinary general-purpose products. it can. Therefore, it is possible to form optical connections corresponding to various connection forms regardless of existing or new installations without greatly changing the existing optical connection forms.
[0059]
【The invention's effect】
As described above, according to the present invention, when the mode field diameters of the optical fibers connected to each other are different, the mode field diameter conversion member that reduces the MFD difference between the optical fibers between the optical fiber connection portions. Can be easily inserted to suppress an increase in connection loss. In addition, it is possible to cope with various connection forms without greatly changing the connection form for this purpose, and it is excellent in workability of optical connection and can be inexpensive.
[Brief description of the drawings]
FIG. 1 shows the present invention. First connection related to It is a figure explaining a form.
FIG. 2 First connection related to It is a figure explaining a form.
FIG. 3 Second connection related to It is a figure which shows the manufacture example of the intermediate optical fiber used with a form.
FIG. 4 The present invention First connection related to It is a figure which shows the other example of manufacture of the intermediate optical fiber used by a form.
FIG. 5 is a diagram illustrating the relationship between MFD difference and mismatch loss.
FIG. 6 is a diagram for explaining a reduction state of mismatch loss due to an intermediate optical fiber.
FIG. 7 is a diagram illustrating an outline of an optical communication device according to the present invention.
FIG. 8 is a diagram illustrating a specific example of an optical connection component according to the present invention.
FIG. 9 is a diagram illustrating another specific example of the optical connecting component according to the present invention.
FIG. 10 is a diagram illustrating a conventional technique.
FIG. 11 is a diagram for explaining another conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20, 22 ... Optical connector, 21 ... Optical connection component, 23 ... 1st optical fiber, 24 ... Mode field diameter conversion member, 24a, 24b ... End surface, 25 ... 2nd optical fiber, 26 ... Ferrule, 27 ... Ferrule Holding member, 28, 28a, 28b ... connecting housing, 29 ... sleeve, 30, 31 ... intermediate optical fiber, 30a, 31a ... core part, 30b, 31b ... clad part, 32, 33 ... optical fiber, 32a, 33a ... core 32b, 33b ... clad part, 32c ... MFD enlargement part, 34 ... cutting part, 35 ... fusion splicing part, 40 ... optical communication equipment, 41 ... equipment housing, 42 ... planar optical waveguide, 43, 44 ... light Fiber array, 45 ... multi-fiber optical fiber cord, 50, 52 ... optical connector, 51 ... optical connection component, 53 ... ferrule, 54 ... ferrule holding member, 55 ... optical connector Enclosure, 56 ... Spring, 57 ... Boot, 58 ... Mode field diameter conversion member, 59 ... Optical connection component housing, 60 ... Optical connector engagement member, 61 ... Split sleeve, 62 ... Sleeve fixing member, 63 ... Optical connection 64, connection adapter, 65, mode field diameter conversion member, 66, optical connection component housing, 67, optical connector engagement member, 68, split sleeve, 69, connection adapter housing, 70, optical connector engagement member 71 ... Split sleeve.

Claims (9)

An optical connecting parts for detachably connecting different optical fibers of the mode field diameter by an optical connector together, the connection housing of the optical connecting parts, housing the mode field diameter conversion member having a connection end face at both ends, An optical connecting component comprising split sleeves fitted with ferrules of the optical connector on both sides of the mode field diameter conversion member .   2. The light according to claim 1, wherein the mode field diameter conversion member is formed of a single short optical fiber having a mode field diameter intermediate between the mode field diameters of the optical fibers to be connected. Connection parts.   The mode field diameter conversion member has a mode field diameter that is tapered in the longitudinal direction so that the mode field diameter is the same as or close to the mode field diameter of each of the optical fibers connected on the connection end face side. The optical connection component according to claim 1, wherein the optical connection component is formed of a short optical fiber.   The optical connection component according to claim 3, wherein the mode field diameter conversion member has a mode field diameter converted by heat-treating a single optical fiber.   4. The mode field diameter conversion member according to claim 3, wherein the mode field diameter is converted by fusion splicing two optical fibers having different mode field diameters and heat-treating the fusion splicing portion. Optical connection parts. An optical connection method for detachably connecting different optical fibers of the mode field diameter by an optical connector together, the mode field diameter conversion member having a connection end face at both ends in the connection housing of the optical connection part housed, the on both sides of each of the mode field diameter conversion member, arranged split sleeve ferrule of the optical connector is fitted, connecting different optical fibers of the mode field diameter to each other physician via the mode field diameter conversion member An optical connection method. The optical connection method according to claim 6 , wherein a mode field diameter at a connection end face of the mode field diameter conversion member is within ± 10% of a mode field diameter of the optical fiber to be connected. An optical fiber having an optical fiber wiring portion, an optical fiber having a mode field diameter of 8 μm or less is used for the optical wiring inside the device housing, and a mode field is used for the optical wiring outside the device housing from the optical fiber used for the optical wiring inside the device housing. A communication device using an optical fiber having a large diameter , comprising: an optical connection member that optically connects an optical fiber in the device housing and an optical fiber outside the device housing with an optical connector; and in the connection housing of the optical connection member A mode field diameter conversion member having connection end faces at both ends is housed in each, and split sleeves to which the ferrules of the optical connector are fitted are arranged on both sides of the mode field diameter conversion member. Optical communication equipment. 9. The optical communication device according to claim 8 , wherein the optical fiber used for the optical wiring in the device housing has an allowable bending minimum radius of 15 mm or less.

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