Optical waveguides – With optical coupler – Particular coupling structure
Reexamination Certificate
1998-06-29
2001-10-09
Bovernick, Rodney (Department: 2874)
Optical waveguides
With optical coupler
Particular coupling structure
C385S043000
Reexamination Certificate
active
06301412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an apparatus and method for making a multi-branching optical coupler.
2. Description of the Related Art
With the rapid progress of optical fiber transmission technology, optical data links, which utilize optical fibers for transmitting data between computers or between a computer and a terminal, have been the subject of much research and development. In configuring such an optical data link, a multi-branching optical coupler, which is capable of mixing light signals from multiple input optical fibers and distributing the mixed light signals evenly and with a low loss to multiple output optical fibers, is an essential device. The method for making such optical star couplers is disclosed in Japanese patent applications, Laid-Open No. 60-24505 and Laid-Open No. 63-205616.
The optical star coupler disclosed in Japanese Patent Application Laid-Open No. 60-24505 is made by inserting an optical fiber bundle into a glass tube, and heating and drawing the glass tube so that the optical fibers are substantially evenly arranged with respect to the center of the coupler. The optical star coupler disclosed in Japanese Patent Application Laid-Open No. 63-205616 is made by coupling multiple 3 dB optical couplers in multi-stages, realizing many branch points.
In the case of the former optical coupler, the optical fibers are arranged symmetrically about the center of the coupler. However, in this case, since no fiber exists at the center, the symmetry with respect to the injection port is poor. As a result, it is difficult to achieve equi-branching characteristics. In the case of the latter optical coupler, unlike a batch fuse type coupler, several couplers have been coupled in multi-stages to form the optical star coupler. As a result, the overall size of the optical star coupler is significantly increased.
Another optical fiber type star coupler disclosed in Japanese Patent Application Laid-Open No. 63-70208 is made by twisting, fusing, and drawing an optical fiber bundle, and covering the optical fiber bundle with a glass tube. However, in this optical fiber type star coupler, the initial arrangement of the fibers is not preserved after the twisting, fusing, and drawing process. As a result, the variance of the intensities of the light output from the fibers is hard to control Therefore, in this case, it is difficult to achieve equi-branching characteristics.
In addition, a multi-branching optical coupler having four branches disclosed in OEC 1994 pp364 is made arranging five fibers on a plane taking symmetry into consideration. In this case, one of these fibers does not contribute to the outputs. This fiber is difficult to produce. Moreover, since the five fibers are arranged horizontally in a row, the width of the coupler is increased. As a result, the size of the coupler case is increased significantly also.
In addition, a method for making a fiber optic coupler and a 1×N fiber optic coupler is disclosed in Japanese Patent Application Laid-Open No. H7-140346. According to this method, N fibers are first inserted into a glass tube. The glass tube is then heated and drawn, collapsing the entire glass tube. This method involves a process for putting the fibers into the glass tube, and a process for collapsing the entire glass tube. It is not easy to make these couplers due to these making processes. In addition, it is extremely difficult to collapse the entire glass tube without distorting the fibers. Moreover, the collapsed fibers are deformed, in which case, the light transmission properties of the fibers, for example, the polarized wave dependency, can be adversely affected.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an apparatus and method capable of easily making the multi-branching optical coupler.
According to a first aspect of the present invention, the apparatus for making a multi-branching optical coupler has a mask including a center hole for passing through a center fiber selected from the plurality of fibers, and a plurality of surrounding holes for passing through surrounding fibers that are remainder of the plurality of fibers, such that the surrounding holes are arranged around the center hole and are separated from each other by an equal distance. The apparatus for making a multi-branching optical coupler further has a rotation stage for rotating the mask so as to twist the surrounding fibers about the center fiber, a heating apparatus for heating the center fiber and the surrounding fibers that have been twisted by the rotation stage about the center fiber; and a drawing stage for drawing the center fiber and surrounding fibers that have been heated with the heating apparatus.
According to a second aspect of the present invention, the apparatus for making a multi-branching optical coupler further has a stress adjusting unit for holding stresses, which are generated in the center fiber and each of the surrounding fibers, when the center fiber and surrounding fibers are twisted with the rotation stage, respectively. According to a third aspect of the present invention, the apparatus for making a multi-branching optical coupler, further comprises a clamp installed between the stress adjusting unit and the heating apparatus, for fixing the center fiber and surrounding fibers. According to a fourth aspect of the present invention, the mask has seven or more surrounding holes and the diameter of the center hole is larger than the diameters of the surrounding holes.
According to a fifth aspect of the present invention, the apparatus for making a multi-branching optical coupler, which branches light injected to one fiber into a plurality of fibers, has: a rotation stage for twisting the plurality of fibers; a stress adjusting unit for holding a stress, which is generated in each of the plurality of fibers when the fibers are twisted with the rotation stage; a heating apparatus for heating the plurality of fibers that have been twisted with the rotation stage; and a drawing stage which shifts for drawing the fibers that have been heated with the heating apparatus.
According to a sixth aspect of the present invention, the apparatus for making a multi-branching optical coupler further has a clamp installed between the stress adjusting unit and the heating apparatus for fixing the fibers. According to a seventh aspect of the present invention, the stress adjusting unit has elastic holding units for elastically holding the plurality of fibers independently from each other.
According to an eighth aspect of the present invention, the apparatus for making a multi-branching optical coupler further has a mask including a center hole for passing through a center fiber selected from the plurality of fibers, and a plurality of surrounding holes for passing through surrounding fibers that are remainder of the plurality of fibers, such that the surrounding holes are arranged around the center hole and are separated from each other by an equal distance. The stress-adjusting unit holds the center fiber that has passed through the center hole and the surrounding fibers that have passed through the surrounding holes.
According to a ninth aspect of the present invention, the apparatus for making a multi-branching optical coupler further has a monitor light outputting apparatus for injecting a monitor light to a light input end of the center fiber; and a light receiving apparatus for monitoring a light output from an output end of the center fiber and another light output from one of the surrounding fibers.
According to a tenth aspect of the present invention, the apparatus for making a multi-branching optical coupler further has a stopping means for stopping the shift of the drawing stage when the intensity of the light output from the output end of the center fiber becomes substantially equal to the intensity of the another light output from the one of the surrounding fibers.
According to a eleventh aspect of the present invention, the mask has seven or more surround
Abe Jun
Ejima Seiki
Koya Kazuo
Maeda Sayuri
Mori Tsuneo
Bovernick Rodney
Pillsbury & Winthrop LLP
Shin-Etsu Chemical Co. , Ltd.
Stahl Michael J
LandOfFree
Apparatus and method for making multi-branching optical coupler does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for making multi-branching optical coupler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for making multi-branching optical coupler will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2605265