Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
1999-09-13
2001-12-18
Sikder, Mohammad (Department: 2872)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S086000, C385S087000, C385S051000, C385S052000, C385S053000
Reexamination Certificate
active
06331081
ABSTRACT:
This application is the national phase of international application PCT/JP98/01019 filed Mar. 11, 1998 which designated the U.S.
TECHNICAL FIELD
The present invention relates to an optical transmission component optically connected, at an end face thereof, to another optical component; and, in particular, to an optical transmission component such as optical connector or optical module utilizing an optical fiber.
BACKGROUND ART
In optical transmission, for relaying, amplification, and the like, it is necessary to optically connect optical fibers together or an optical fiber to a light-emitting device, a light-receiving device, an amplifier, or the like. Such an optical connection is realized by butting the end faces of optical fibers together or the end face of the optical fiber and the light-receiving (or light-emitting) face of such a device against each other.
For example, regarding optical connectors, various kinds of techniques have been proposed concerning the method of processing and fixing the front end face of an optical fiber. The method of making an optical connector disclosed in Japanese Patent Application Laid-Open No. 7-306,333 describes a method for rounding corners in a front end portion of an optical fiber by heat treatment, the chemical processing with an acid or the like, and physical processing with abrasive grains. Also, the method of processing an end face of an optical fiber disclosed in Japanese Patent Application Laid-Open No. 55-138,706 is a method in which the end face of the optical fiber is heated by discharge such as to yield a roundness with a radius not smaller than the radius of the optical fiber. These documents, however, do not disclose any specific technique for fixing an optical fiber to an optical connector.
The method of making an optical connector disclosed in Japanese Patent Application Laid-Open No. 58-108,507 employs a technique in which, after a front end face of a cut optical fiber is melted so as to become smooth, the optical fiber is inserted into the core of the connector and secured therein with an adhesive. Here, the position to secure the optical fiber is where the tip of the optical fiber and the tip of the core substantially match each other. In the matching process, the optical fiber is moved and positioned such that the tip of the optical fiber is disposed at the same position as the front end face of the core or slightly inside thereof, while being observed through a microscope or by placing a planar jig made of a material softer than the optical fiber at the tip of the core.
On the other hand, the optical connector disclosed in “Fiber PC Optical Connector” in NTT R&D vol. 45, No. 6 (1996), pp. 95-100 employs a method in which an optical fiber subjected to end-face processing for chamfering the cleavage plane thereof is fixed such as to project from an end face of a ferrule. The amount of projection is a value at which, in a connected state, the optical fiber is buckled by a pressure. It aims at maintaining a contact pressure by buckling. Consequently, a space for allowing the optical fiber to flex is secured within the ferrule.
DISCLOSURE OF THE INVENTION
In the conventional techniques mentioned above, the grinding process in the end-face processing is disadvantageous in that it takes time to process. Also, the chemical processing is hard to yield a form suitable for so-called PC (Physical Contact) in which front end faces of optical fibers are butted together for establishing an optical connection, and thus is disadvantageous. The techniques of Japanese Patent Application Laid-Open Nos. 7-306,333 and 55-138,706 disclosing, instead, heat treatments by discharge aim at eliminating burrs of optical fibers upon a discharging process, and none of them takes account of making a PC-suitable form.
It can be concluded that considerations have conventionally been insufficient for carrying out the end-face processing of an optical fiber in view of PC and, further, for placing and fixing the optical fiber into an optical connector in view of PC.
In particular, in the case where an optical fiber ribbon including a plurality of optical fibers is cut and fixed to a connector, a fluctuation of about 8 to 20 &mgr;m inevitably occurs at the front end position of the optical fiber. In the technique disclosed in the publication “Fiber PC Optical Connector” mentioned above, the fluctuation in length is absorbed while establishing the PC by buckling the optical fiber, whereby the possibility of the optical fiber being broken or connection loss being enhanced due to the buckling would certainly increase. Hence, it is disadvantageous in that there is a risk of the reliability thereof becoming insufficient.
In view of the above-mentioned problems, it is an object of the present invention to provide an optical transmission component having a connecting end face capable of connecting at a high accuracy, and a method of making the same.
In order to overcome the above-mentioned problems, the method of making an optical transmission component is a method of making an optical transmission component in which one or a plurality of optical fibers are fixed to a main body of an optical transmission component with one end face of each optical fiber being exposed, and thus exposed end face is used as a connecting end face to be optically connected to another optical transmission component, the method comprising: (1) a step of removing a coating of each optical fiber so as to expose a predetermined length of an optical fiber; (2) a step of processing thus exposed end face of the optical fiber by spark discharge processing for a short period of time; and (3) a process of inserting thus processed optical fiber into the main body of the optical transmission component and fixing the optical fiber to the main body while adding a predetermined pressure to the optical fiber along the optical axis thereof from the end face side.
In the optical transmission component made according to these steps, burrs are eliminated from the connecting end face of each optical fiber due to the discharge processing, whereby the end face is processed into a PC-suitable form. Also, since the processed optical fibers are secured while a predetermined pressure is being added thereto along their optical axis direction from the end face side, their front ends on the end face side align with each other. Hence, PC can securely be established in the case of multi fibers as well.
Preferably, the predetermined pressure is less than the buckling load of the optical fiber. In this case, the optical fiber is prevented from buckling upon fixing, whereby its quality can be maintained.
Preferably, the optical fibers are inserted into the main body of the optical transmission component such that their respective end faces project from the connecting end face of the main body by a predetermined amount. As a consequence, the tip positions of the end faces can securely be aligned with each other. Preferably, the amount of projection is not greater than 0.2 mm.
The optical fibers can be fixed with an adhesive. At least a part of the main body may be made of a UV-transmitting material, and a UV-curable adhesive may be used as the adhesive and solidified upon irradiation with ultraviolet rays, so as to secure the optical fiber. Alternatively, the adhesive may be a thermosetting adhesive.
Also, the optical fibers may mechanically be fixed into the main body. The main body may have an optical fiber positioning portion and an optical fiber fixing portion, and the optical fiber fixing portion may hold the optical fiber by utilizing a deformation of a member. Further, it is preferred that the optical fiber fixing portion be constituted by at least two holding members for holding the optical fiber from both directions across the optical fiber, and a pressing member. More preferably, at least one of these holding members is made of aluminum or a plastic.
Further, in the case where, in the step of fixing the optical fiber, a wedge-shaped member is inserted into a recess formed at a juncture between the holding me
Kakii Toshiaki
Ohtsuka Kenichiro
Ueda Tomohiko
Sikder Mohammad
Sumitomo Electric Industries Ltd.
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