Optical connector with optical fibers and method for manufacturing the same

An optical connector attached to a plurality of buffered optical fibers each including: a bare optical fiber; and a tube in which the bare optical fiber is inserted in. A multi-fiber optical connector is connected to first ends of the buffered optical fibers, and a plurality of single-fiber optical connectors are respectively connected to second ends of the buffered optical fibers. The multi-fiber optical connector includes: a ferrule fixed to ends of the bare optical fibers; a connector housing that houses the ferrule therein; and a tube fixing portion that fixes the tubes to the connector housing. The buffered optical fiber has a bare fiber fixing portion in which the bare optical fiber and the tube are fixed at a location closer to the ferrule than the tube fixing portion within the multi-fiber optical connector.

TECHNICAL FIELD

The present invention relates to an optical connector with optical fibers and a method of manufacturing the same, and more particularly to an optical connector with optical fibers that includes a multi-fiber optical connector from which a plurality of buffered optical fibers are branched and a method of manufacturing the same.

BACKGROUND

There has heretofore been known an optical connector with optical fibers, what is called a fanout code, in which a plurality of buffered optical fibers are branched from a multi-fiber optical connector while single-fiber optical connectors are respectively connected to ends of the branched buffered optical fibers (see, e.g., Patent Literature 1).FIG. 1is a diagram schematically showing a structure of a conventional optical connector with optical fibers. As shown inFIG. 1, the conventional optical connector with optical fibers includes a multi-fiber optical connector510, a plurality of buffered optical fibers520branched from the multi-fiber optical connector510, and single-fiber optical connectors530attached to ends of the respective buffered optical fibers520.

Each of the buffered optical fibers520includes a tube521and a bare optical fiber522housed in the tube521. Each of those bare optical fibers522is housed loosely within the tube521. Ends of the tube521and the bare optical fiber522near the single-fiber optical connector530are fixed to a ferrule531in the single-fiber optical connector530. Furthermore, ends of the respective tubes521near the multi-fiber optical connector510are fixed to a connector housing511of the multi-fiber optical connector510. Ends of the respective bare optical fibers522near the multi-fiber optical connector510are fixed to a ferrule512in the multi-fiber optical connector510.

When an optical connector with optical fibers thus constructed is under a low temperature for an environmental test or the like, the tubes521and the bare optical fibers522shrink. The tubes521are formed of a material that has a higher rate of shrinkage (coefficient of thermal expansion) than the material of the bare optical fibers522. Therefore, the tubes521shrink to a larger extent relative to the bare optical fibers522. As a result, as shown inFIG. 2, the bare optical fibers522relatively project from the tubes521into the multi-fiber optical connector510. Thus, the bare optical fibers522are bent within the multi-fiber optical connector510. If the bare optical fibers522are thus bent, the optical characteristics of the bare optical fibers522are deteriorated due to the bend loss. When the buffered optical fibers520become long in length (e.g., over 50 cm in length), the amount of shrinkage of the tubes521increases. Therefore, the deterioration becomes more significant.

PATENT LITERATURE

Patent Literature 1: JP 3835670 B

SUMMARY

One or more embodiments of the present invention provide an optical connector with optical fibers that is unlikely to cause bare optical fibers to be bent within a multi-fiber optical connector and is capable of maintaining good optical characteristics even if it is under a low-temperature environment or buffered optical fibers are pushed into the multi-fiber optical connector.

Furthermore, one or more embodiments of the present invention provide a method of manufacturing an optical connector with optical fibers that can produce such an optical connector with optical fibers by a simple process.

According to one or more embodiments of the present invention, there is provided an optical connector with optical fibers that is unlikely to cause bare optical fibers to be bent within a multi-fiber optical connector and is capable of maintaining good optical characteristics even if it is under a low-temperature environment or buffered optical fibers are pushed into the multi-fiber optical connector. The optical connector with optical fibers has a plurality of buffered optical fibers each including a bare optical fiber and a tube in which the bare optical fiber is loosely inserted, a multi-fiber optical connector connected to first ends of the plurality of buffered optical fibers, and a plurality of single-fiber optical connectors respectively connected to second ends of the plurality of buffered optical fibers. The multi-fiber optical connector includes a ferrule to which the ends of the bare optical fibers of the plurality of buffered optical fibers are fixed, a connector housing that houses the ferrule therein, and a tube fixing portion in which the tubes of the plurality of buffered optical fibers are fixed to the connector housing. Each of the plurality of buffered optical fibers has a bare fiber fixing portion in which the bare optical fiber and the tube are fixed at a location closer to the ferrule than the tube fixing portion within the multi-fiber optical connector.

According to this configuration, in one or more embodiments, tubes of buffered optical fibers are fixed to a tube housing in a tube fixing portion. Therefore, when a multi-fiber optical connector is connected to a mating plug, for example, the buffered optical fibers are prevented from being pushed into the multi-fiber optical connector even if an axial force is applied to the buffered optical fibers. Accordingly, bare optical fibers in the buffered optical fibers are prevented from being bent within the multi-fiber optical connector. Thus, the optical characteristics of the bare optical fibers can be prevented from being deteriorated. Furthermore, the bare optical fiber and the tube of each of the buffered optical fibers are fixed closer to a ferrule than the tube fixing portion by a bare fiber fixing portion. Therefore, even if the optical connector with optical fibers is under a low temperature for an environmental test or the like to cause the tubes to shrink, the bare optical fibers can be prevented from projecting from the bare fiber fixing portion toward the ferrule. Accordingly, the bare optical fibers in the buffered optical fibers are prevented from being bent within the multi-fiber optical connector. Thus, the optical characteristics of the bare optical fibers can be prevented from being deteriorated.

In one or more embodiments, in order to reduce forces applied to the buffered optical fibers at the root of the multi-fiber optical connector, it is preferable to form the tube fixing portion at an end of the connector housing near the single-fiber optical connector. Furthermore, it is preferable to form the bare fiber fixing portion at an end of the tube.

According to one or more embodiments of the present invention, there is provided a method of manufacturing an optical connector with optical fibers that can produce the aforementioned optical connector with optical fibers by a simple process. In this method, a plurality of buffered optical fibers each including a bare optical fiber and a tube in which the bare optical fiber is loosely inserted are prepared. First ends of the bare optical fibers of the plurality of buffered optical fibers are fixed to a ferrule of a multi-fiber optical connector, and a first adhesive material is applied onto each of the bare optical fibers over a predetermined length from a location far away from the ferrule by a predetermined distance. Each of the tubes of the plurality of buffered optical fibers is moved toward the ferrule until an area of the bare optical fibers to which the first adhesive material has been applied is covered with the tube. After each of the tubes has been moved, the first adhesive material is hardened to form a bare fiber fixing portion in which the bare optical fibers and the tubes are fixed. A connector housing of the multi-fiber optical connector is assembled so that the ferrule is housed in the connector housing. A second adhesive material is filled into between the connector housing and the tubes at a location farther away from the ferrule than the bare fiber fixing portion. The second adhesive material filled between the connector housing and the tubes is hardened to form a tube fixing portion in which the tubes of the plurality of buffered optical fibers are fixed to the connector housing. Single-fiber optical connectors are attached to second ends of the plurality of buffered optical fibers, respectively.

With this method, in one or more embodiments, an optical connector with optical fibers that can maintain good optical characteristics as described above can be manufactured by a simple process.

Furthermore, according to one or more embodiments, it is preferable to fix the tubes of the plurality of buffered optical fibers to each other with a third adhesive material before each of the tubes of the plurality of buffered optical fibers is moved toward the ferrule. When a plurality of tubes are thus integrated with each other, those tubes can collectively be moved toward the ferrule and fixed. Accordingly, the manpower required to move and fix a plurality of tubes can be reduced.

According to one or more embodiments of the present invention, tubes of buffered optical fibers are fixed to a tube housing in a tube fixing portion. Therefore, when a multi-fiber optical connector is connected to a mating plug, for example, the buffered optical fibers are prevented from being pushed into the multi-fiber optical connector even if an axial force is applied to the buffered optical fibers. Accordingly, bare optical fibers in the buffered optical fibers are prevented from being bent within the multi-fiber optical connector. Thus, the optical characteristics of the bare optical fibers can be prevented from being deteriorated. Furthermore, the bare optical fiber and the tube of each of the buffered optical fibers are fixed closer to a ferrule than the tube fixing portion by a bare fiber fixing portion. Therefore, even if the optical connector with optical fibers is under a low temperature for an environmental test or the like to cause the tubes to shrink, the bare optical fibers can be prevented from projecting from the bare fiber fixing portion toward the ferrule. Accordingly, the bare optical fibers in the buffered optical fibers are prevented from being bent within the multi-fiber optical connector. Thus, the optical characteristics of the bare optical fibers can be prevented from being deteriorated.

DETAILED DESCRIPTION

Embodiments of an optical connector with optical fibers according to the embodiments of the present invention will be described below with reference toFIGS. 3 to 8F. InFIGS. 3 to 8F, the same or corresponding components are denoted by the same or corresponding reference numerals and will not be described below repetitively. Furthermore, inFIGS. 3 to 8F, the scales or dimensions of components may be exaggerated, or some components may be omitted.

FIG. 3is a perspective view showing an optical connector with optical fibers1according to one or more embodiments of the present invention. As shown inFIG. 3, the optical connector with optical fibers1includes a plurality of buffered optical fibers10, single-fiber optical connectors20attached to ends of the respective buffered optical fibers10, and a multi-fiber optical connector30attached to the other ends of the buffered optical fibers10. The buffered optical fibers10are bundled at the root of the multi-fiber optical connector30and branched from the multi-fiber optical connector30toward the single-fiber optical connectors20. The optical connector with optical fibers1in one or more embodiments includes 16 buffered optical fibers10. However, the number of the buffered optical fibers10is not limited to the illustrated example. Furthermore, the shapes and types of the single-fiber optical connectors20and the multi-fiber optical connector30are not limited to the illustrated example.

FIG. 4is a cross-sectional view of the buffered optical fiber10taken on a plane perpendicular to an axis of the buffered optical fiber10. As shown inFIG. 4, each of the buffered optical fibers10includes a bare optical fiber12and a tube14that accommodates the bare optical fiber12therein. The inside diameter of the tube14is greater than the outside diameter of the bare optical fiber12. Thus, a space16is formed between an outer circumferential surface12A of the bare optical fiber12and an inner circumferential surface14A of the tube14. In this manner, the bare optical fiber12is loosely inserted within the tube14. Accordingly, the bare optical fiber12can be bent or moved within the tube14. For example, a tube having an outside diameter of about 0.9 mm and an inside diameter of about 0.5 mm may be used for the tube14, and a bare optical fiber having an outside diameter of 0.25 mm may be used for the bare optical fiber12.

FIG. 5is a plan view showing the multi-fiber optical connector30,FIG. 6is a front view thereof, andFIG. 7is a cross-sectional view taken along line A-A ofFIG. 6. As shown inFIGS. 5 to 7, the multi-fiber optical connector30includes a ferrule31for fixing the bare optical fibers12in the buffered optical fibers10, a front housing32that accommodates the ferrule31therein, a rear housing33that engages with the front housing32, a tube housing34attached to a rear end of the rear housing33, a coupling35that covers a periphery of the front housing32, and a protective boot36that covers a rear end portion of the rear housing33and the tube housing34. For example, the protective boot36is formed of an elastic material such as rubber. Thus, the protective boot36protects the buffered optical fibers10from extreme bending. InFIG. 7, the buffered optical fibers10are illustrated as being thinned out for better understanding.

For example, the ferrule31is a pin-guided MT ferrule. As shown inFIG. 7, the ferrule31has flange portions31A projecting outward. The flange portions31A are configured to engage with protrusions32A of the front housing32. Furthermore, the rear housing33has elastic hooks33A projecting outward. When the elastic hooks33A engage with engagement holes32B formed in the front housing32, the rear housing33is secured to the front housing32.

A spring37is disposed between the front housing32and the rear housing33. The ferrule31is biased frontward by this spring37. Furthermore, springs38are disposed between the front housing32and the coupling35. The coupling35is biased frontward by those springs38.

It is preferable to form the tube housing34of an elastic material. For example, a heat-shrinkable tube, which is brought into intimate contact with an object due to thermal contraction so as to cover the object, may be used for the tube housing34. In one or more embodiments, as described above, the front housing32and the rear housing33engage with each other, and the tube housing34is attached to the rear housing33. Accordingly, the front housing32, the rear housing33, and the tube housing34may collectively be considered as a connector housing that houses the ferrule31therein.

As shown inFIG. 7, the bare optical fibers12of the buffered optical fibers10extend inside of the tube housing34, the rear housing33, and the front housing32of the multi-fiber optical connector30to the ferrule31. In one or more embodiments, the tubes14of the buffered optical fibers10extend to the middle of the tube housing34. It is preferable to align end faces of those tubes14in an axial direction. For example, the tubes14are positioned such that the distance L1from an end face of the ferrule31to the end faces of the tubes14is 30 mm. This distance L1is determined in consideration of an allowable bend radius of the multi-fiber optical connector30.

Furthermore, as shown inFIG. 7, a tube fixing portion40to fix the tubes14of the buffered optical fibers10to the tube housing34is formed at a rear end of the connector housing, i.e., at a rear end of the tube housing34. For example, the tube fixing portion40is formed of an adhesive material or the like. Thus, the tubes14of the buffered optical fibers10are fixed to the tube housing34(connector housing) by the tube fixing portion40. Therefore, when the multi-fiber optical connector30is connected to a mating plug, for example, the buffered optical fibers10are prevented from being pushed into the multi-fiber optical connector30even if an axial force is applied to the buffered optical fibers10. Accordingly, the bare optical fibers12in the buffered optical fibers10are prevented from being bent within the multi-fiber optical connector30. Thus, the optical characteristics of the bare optical fibers12can be prevented from being deteriorated.

Furthermore, a bare fiber fixing portion50to fix the tubes14and the bare optical fibers12within those tubes14to each other is formed at ends of the tubes14that have been aligned within the tube housing34as described above. This bare fiber fixing portion50is located closer to the ferrule31than the aforementioned tube fixing portion40. For example, the bare fiber fixing portion50is formed of an adhesive material or the like. In this manner, the bare optical fiber12and the tube14of each of the buffered optical fibers10are fixed closer to the ferrule31than the tube fixing portion40by the bare fiber fixing portion50. Therefore, even if the optical connector with optical fibers1is under a low temperature for an environmental test or the like to cause the tubes14to shrink, the bare optical fibers12can be prevented from projecting from the bare fiber fixing portion50toward the ferrule31. Accordingly, the bare optical fibers12in the buffered optical fibers10are prevented from being bent within the multi-fiber optical connector30. Thus, the optical characteristics of the bare optical fibers12can be prevented from being deteriorated. In order to attain such advantageous effects, the bare fiber fixing portion50may preferably have some length along the axial direction. For example, the length L2of the bare fiber fixing portion50along the axial direction may preferably be greater than or equal to 10 mm.

As shown inFIG. 3, the buffered optical fibers10are branched from the multi-fiber optical connector30, and a single-fiber optical connector20is attached to an end of each of the buffered optical fibers10. Within each of the single-fiber optical connectors20, the bare optical fiber12and the tube14of the buffered optical fiber10are both fixed to the ferrule (not shown). Any conventional known method may be used to fix the buffered optical fibers10to the single-fiber optical connectors20.

Now a method of manufacturing an optical connector with optical fibers thus constructed will be described with reference toFIGS. 8A to 8F. First, as shown inFIG. 8A, a bare optical fiber12of each of buffered optical fibers10is attached to a ferrule31and fixed to the ferrule31. Next, as shown inFIG. 8B, a first adhesive material51is applied onto each of the bare optical fibers12over a predetermined length (L2illustrated inFIG. 7) from a location spaced apart from the ferrule31by a certain distance (L1illustrated inFIG. 7).

Then, as shown inFIG. 8C, the respective tubes14of the buffered optical fibers10are moved toward the ferrule31. At that time, the tubes14are moved until an area of the bare optical fibers12where the first adhesive material has been applied is covered with the tubes14. As shown inFIG. 8C, it is preferable to position the tubes14so that the first adhesive material51is filled up to end faces of the tubes14. After the movement of the tubes14has been completed, the first adhesive material51is hardened to form a bare fiber fixing portion50. Thus, the bare optical fibers12and the tubes14are fixed to each other. For example, an epoxy resin adhesive material such as “High-super 5” sold by Cemedine Co., Ltd. may be used for the first adhesive material51. It is preferable to use an adhesive material having a high hardness for the first adhesive material51.

Next, as shown inFIG. 8D, a multi-fiber optical connector30is assembled. Specifically, a spring37and a rear housing33of the multi-fiber optical connector30are moved toward the ferrule31, and a front housing32is inserted from an opposite side of the ferrule31to those components. The ferrule31, the front housing32, and the rear housing33are incorporated with each other by engagement of the flange portions31A of the ferrule31with the protrusions32A of the front housing32and engagement of the elastic hooks33A of the rear housing33with the engagement holes32B of the front housing32. Furthermore, the springs38and a coupling35are attached around the front housing32. The tube housing34is moved toward the ferrule31and attached to an end of the rear housing33.

Next, as shown inFIG. 8E, a second adhesive material41is filled into between an rear end of the tube housing34and the tubes14. The location where the second adhesive material41is filled may not be at the rear end of the tube housing34but should be farther away from the ferrule31than the bare fiber fixing portion50. It is preferable to fill the second adhesive material41into the rear end of the tube housing34in order to reduce forces applied to the buffered optical fibers10at the root of the multi-fiber optical connector30.

Thereafter, the second adhesive material41is hardened to form a tube fixing portion40. Thus, the tubes14of the buffered optical fibers10are fixed to the tube housing34(the connector housing). For example, it is preferable to use an adhesive material that is relatively elastic, such as “Super X” sold by Cemedine Co., Ltd., for the second adhesive material41. If the tube fixing portion40is formed of such an elastic adhesive material, the tube fixing portion40is also bent when the buffered optical fibers10are bent. Accordingly, any deflection is unlikely to be caused within the bare optical fibers12, and breakage of the bare optical fibers12can be prevented.

Next, as shown inFIG. 8F, a protective boot36is moved toward the ferrule31. The protective boot36is attached to a rear end of the rear housing33so that the rear ends of the tube housing34and the rear housing33are covered with the protective boot36. Then single-fiber optical connectors20are respectively attached to the other ends of the buffered optical fibers10by using any conventional known method. With the above steps, an optical connector with optical fibers1as shown inFIG. 3is completed.

Before the respective tubes14of the buffered optical fibers10are moved toward the ferrule31, ends of the tubes14of the buffered optical fibers10may be aligned with each other, and, in this state, the tubes14may be fixed and integrated with each other by an adhesive material (third adhesive material) or the like. When a plurality of tubes14are integrated with each other, those tubes14can collectively be moved toward the ferrule31and fixed. Accordingly, the manpower required to move and fix a plurality of tubes14can be reduced.

INDUSTRIAL APPLICABILITY

One or more embodiments of the present invention is suitably used for an optical connector with optical fibers that includes a multi-fiber optical connector from which a plurality of buffered optical fibers are branched.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

1Optical connector with optical fibers

10Buffered optical fiber

12Bare optical fiber

41Second adhesive material

50Bare fiber fixing portion

51First adhesive material