Broad bandwidth, single mode fiber optic coupler and method of manufacture
AssigneeE-Tek Dynamics, Inc.
InventorsJing-Jong Pan, Donna Yu
Life of this patent
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Abstract
The present invention provides for a fiber optic coupler of first and second optic fibers formed by a length of the two fibers. The first optic fiber along the length has a different core diameter than that of the second optic fiber. At the both ends of the length the first and second optic fibers are twisted about each other with a central portion in which said first and second optic fibers are fused substantially parallel to each other. The resulting coupler is such that an input light signal is split into output light signals in a predetermined power ratio on the two optic fibers with the coupled power ratio relatively insensitive for a predetermined range of signal wavelengths.
Claims25
A fiber optic coupler of first and second optic fibers, each optic fiber having a core and a cladding, said coupler comprising:
- a length of said first and second optic fibers, said first optic fiber along said length having a different propagation constant than that of said second optic fiber, said length having two ends, said first and second optic fibers twisted together at each end and substantially parallel to each other between said two ends;
- a portion of said length of said first and second optic fibers fused between said first and second ends, said fused portion disposed between and separated from said first and second twists;
- whereby an input light signal to said coupler is split into output light signals in a predetermined coupled power ratio on said first and second optic fibers, said power ratio relatively insensitive for a predetermined range of wavelengths of said input light signal.
A method of manufacturing a fiber optic coupler comprising:
- providing first and second optical fibers, said optical fibers having mismatched propagation constants;
- forming said fibers into two twists separated by a substantially parallel section of said fibers;
- heating a portion of said parallel section to fuse said heated portion of said fibers, said heated portion being disposed between said two twists and separated from said two twists;
- pulling said fibers as said heated portion of said fibers are fused;
- and
- stopping said fusing and pulling steps when a predetermined coupled power ratios is reached;
- whereby a fiber optic coupler having a coupled power ratio relatively insensitive for a predetermiend range of signal wavelengths.
A method of manufacturing a fiber optic coupler comprising:
- providing first and second optical fibers having mismatched propagation constants;
- forming said fibers into two twists separated by a parallel section;
- heating a portion of said parallel section disposed between said two twists;
- pulling said portion while heating said portion of said section so as to vary a coupling length extending along said portion, said heated portion being separated from said two twists so as to inhibit variation in coupling co-efficients along said twists when said portion is pulled;
- placing a light signal into an end of one of said fibers;
- and
- monitoring said light signal on any one of said fibers opposite said end during the heating and pulling steps.
Dependencies are inferred from the claim text.