Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
1999-08-25
2001-02-27
Ngo, Hung N. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C385S137000, C385S062000
Reexamination Certificate
active
06193421
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an optical connector for connecting optical fibers to each other, and also to a method of attaching the optical connector.
2. Description of the Related Art
Conventionally, a connecting method is employed in which a short optical fiber is previously attached to a ferrule of an optical connector and an optical fiber to which the optical connector is to be connected is then connected to the short optical fiber. In the method, since the short optical fiber is previously attached to the ferrule, the front end of the ferrule can be previously polished under a state where an optical fiber is attached. Therefore, it is not required to conduct a polishing work during a work of attaching the optical connector to an optical fiber, thereby producing an advantage that the work of attaching the optical connector can be completed in a short time.
In each of optical connectors disclosed in Japanese patent publication (Kokai) No. SHO 63-186205, Japanese patent publication (Kokoku) No. HEI 7-69498, and Japanese patent publication (Kokai) No. SHO 64-72105, a short optical fiber of a ferrule is connected to an optical fiber to which the connector is to be attached, by means of fusion or adhesion. The connection due to fusion has a problem in that a fusing apparatus is required, and that due to adhesion has a problem in that a prolonged time period is necessary for conducting the adhesion work. In the case where an ultraviolet-setting resin is used in adhesion, there is another problem in that an ultraviolet irradiator is necessary. When a fusing apparatus or an ultraviolet irradiator is used, there arises a further problem in that a place for installing such an apparatus and a power source must be ensured. Consequently, such methods are not always suitable for a work in the field.
Japanese patent publication (Kokai) No. SHO 63-8613 discloses an optical connector having a cylindrical ferrule consisting of two capillaries. The optical connector is assembled while a short optical fiber is previously fixed to one of the capillaries, and the fixed optical fiber is inserted to the other small bore. The optical fibers are contacted with each other in the small bore. Also an optical connector disclosed in Japanese patent publication (Kokai) No. HEI 6-337325 employs a method in which an optical fiber to which the optical connector is to be connected is contacted with a short optical fiber in a small bore of a capillary. In the case where a capillary is used as described above, since two optical fibers are not fixed in the coupling portion, there is a problem in that variation of the ambient temperature or an operation of handling the optical connector may easily cause misalignment and a gap between the cores of the optical fibers, which are main factors of variation of the optical loss.
By contrast, an optical connector proposed in Japanese patent application No. HEI 7-283420 has a configuration in which a semispherical space is formed at a center portion of a ferrule ,a short optical fiber and an optical fiber to which the optical connector is to be attached are butted together on the ferrule and in the space, and a holding member is fixed to the space, thereby pressing the optical fibers. In the optical connector, fusion and adhesion are not conducted, and hence a fusing apparatus is not necessary and a time period of conducting an adhesion work is not required. Therefore, the proposed optical connector has an advantage that the work of connecting optical fibers together can be completed in a short time. Since the coupling portion of the two optical fibers is pressed by the holding member, moreover, there is an advantage that the coupling state can be ensured. However, the optical connector has the following problem. since a ferrule of a special structure is used, a groove in which optical fibers are butted together is a half-round groove having a shape which is formed b splitting an optical fiber hole into halves. Consequently, the axial misalignment is larger in degree as compared with the case where a V-groove is used.
SUMMARY OF THE INVENTION
The invention has been conducted in view of the above-mentioned circumstances. It is an object of the invention to provide an optical connector which can be easily attached to an optical fiber and in which the attaching work can be completed in a short time and the optical fiber can be surely coupled with a short optical fiber.
According to the invention, an optical connector comprises: a ferrule which incorporates a short optical fiber in a small bore which is formed along a center axis, the short optical fiber being projected from a rear end of the ferrule, the ferrule having a polished front end face; a base member having a holding portion which holds the rear end of the ferrule, and an optical fiber positioning and fixing groove which is formed in an upper face to be continuous with the small bore; a cover member which presses an optical fiber against the optical fiber positioning and fixing groove; and a clamp member which presses the cover member toward the base member, the connector further comprising a wedge insertion portion into which a wedge for pressingly separating the cover member and the base member from each other can be inserted.
According to the invention, in the optical connector of the first aspect, the cover member presses an optical fiber to be attached to the optical connector, toward the base member and against the optical fiber positioning and fixing groove at two portions, i.e., a portion where the short optical fiber is connected with the optical fiber to be attached, and a coated portion of the optical fiber to be attached.
According to the invention, the wedge insertion portion is disposed so as to pressingly separate the cover member and the base member from each other at the two portions, i.e., the portion where the short optical fiber is connected with the optical fiber to be attached, and the coated portion of the optical fiber to be attached.
According to the invention, the optical fiber positioning and fixing groove formed in the base member has a V-like section shape.
According to the invention, the optical fiber positioning and fixing groove formed in the base member has a trapezoidal section shape.
According to the invention, the sort optical fiber has a mirror-finished rear end.
According to the invention, the front end face of the ferrule is polished into a spherical shape.
According to the invention, the front end face of the ferrule is obliquely mirror-polished.
According to the invention, the front end face of the ferrule is mirror-polished in a direction perpendicular to an optical fiber axis.
According to the invention, the base member is made of a substance having a coefficient of linear expansion which is substantially equal to a coefficient of linear expansion of the optical fiber.
According to the invention, an outer periphery of the short optical fiber is coated by a metal or carbon.
According to the invention, a space in which the optical fiber is free is formed between a rear end of the small bore of the ferrule and a front end of a fiber presser which presses the short optical fiber and which is disposed on the base member.
According to the invention, a housing which can be fitted with an SC type optical connector is attached to the optical connector.
According to the invention, the wedge can be inserted or detached under a state where a housing is assembled.
According to the invention, an outer periphery of a rear end face of the short optical fiber is chamfered.
According to the invention, a size of the chamfer of the short optical fiber is not smaller than 10 &mgr;m.
According to the invention, a work of chamfering the short optical fiber is conducted by an electric discharge.
According to the invention, a method of attaching an optical connector uses the above-mentioned optical connector, and comprises the steps of: inserting the wedge into the wedge insertion portion, thereby forming a space into which the optical fiber can
Furukawa Shin-ichi
Hogari Kazuo
Tamekuni Yoshikyo
Ueda Tomohiko
Ngo Hung N.
Pillsbury Madison & Sutro LLP
Sumitomo Electric Industries Ltd
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