Fiber optic coupling device and method of constructing such a device

A process for manufacturing a fiber optic coupler having a most 2.sup.n inputs (n being an integer greater than zero) and one output, comprising the steps of:

• providing a solid part symmetric with respect to two orthogonal midplanes and formed with 2.sup.n -1 convex identical parallel grooves symmetrically distributed with respect to one of said midplanes;
• securing a fiber length in each of said grooves;
• cutting said part and the fiber length along a plane transverse to said midplanes at such a depth to remove half of the cross-section of the fiber length in the other of said midplanes, which is orthogonal to the grooves, for forming a flat abutment surface;
• cutting said part into halves along said midplanes orthogonal to the grooves and locating said halves with two halves of said abutting surface in mutual contact;
• providing an auxiliary part formed with 2.sup.n -1 grooves having the same distribution as the grooves in said solid part;
• locating an output fiber within the central groove of said auxiliary part;
• forming a loop with 2(2.sup.n -1)-2.sup.n end portions of said fiber lengths originating from the end portion of said halves opposed to the cut into the other grooves of said auxiliary part;
• holding the auxiliary part and said two halves in contact with adjacent ends of said fiber lengths in a symetrical end-to-end arrangement for constituting elementary 2-to-1 cascaded couplers.

A fiber optic coupler for coupling 2.sub.n inputs to one output, n being an integer greater than zero, comprising:

• two solid part halves each formed with 2.sup.n -1 identical convex grooves parallel to a common midplane of said part halves which is orthogonal to a front planar surface;
• a plurality of optical fiber lengths each located in one of said grooves, said halves and fibers lengths being cut along a plane transverse to said midplane and to said front planar surface at a depth selected for eliminating substantially half of the cross-section of said fiber lengths in said midplane and for forming respective planar abutment surfaces on said halves;
• and
• an auxiliary part formed with 2.sup.n -1 grooves having the same distribution as the 2.sup.n -1 grooves in said halves,
• said two halves being in mutual contact through their respective abutment surfaces and symetrically located with respect to said abutment surfaces and said auxiliary part being retained in abutment against said front planar surface of said halves,
• and distal end portions of said fiber lengths being located in said grooves of said auxiliary part for coupling each of said distal end portions with the proximal end surfaces of two of said lengths, whereby 2.sup.n -1 elementary 2-to-1 couplings are achieved.