Fiber optic waveguide termination and method of forming same

An optical waveguide comprising:

• a glass fiber core possessing at least one polished end surface and a substantially cylindrical exterior surface;
• a polymeric cladding disposed on and around said exterior surface of said core, said cladding having a refractive index numerically lower than the refractive index of said exterior surface of said core;
• a first polymeric sleeve having a refractive index numerically lower than the refractive index of said exterior surface of said core, and possessing an inner surface disposed around and directly bonded to a portion of said exterior surface of said core adjacent said at least one polished end surface from which the surrounding portion of said polymeric cladding has been removed, an outer surface and a pair of annular end surfaces one of which abuts the unremoved portion of said polymeric cladding and the other of which is substantially flush with said at least one polished end surface;
• and
• a second polymeric sleeve of greater longitudinal length than said first sleeve, said second sleeve possessing an inner surface, a portion of which is telescopically disposed around and bonded to said outer surface of said first sleeve, an outer surface and a pair of annular end surfaces, one of which is substantially flush with said at least one polished end surface and the other of which is disposed around said polymeric cladding, said second sleeve comprising a length of heat shrink tubing which has been heat recovered around said core and said first sleeve, wherein the junction between the first sleeve and the unremoved portion of the polymeric cladding is strain relieved and the polished end surface is substantially centered and mechanically restrained from any motion relative to the outer surface of the second sleeve, all without substantial degradation of the light propagating capability of the waveguide.

An environmentally sealed optical waveguide comprising:

• a glass fiber core possessing a substantially cylindrical exterior surface and a pair of polished end surfaces;
• a polymeric cladding disposed on and around said exterior surface of said core, said cladding having a refractive index numerically lower than the refractive index of said exterior surface of said core;
• a tubular, environmentally protective jacket coaxially disposed around said cladding and said core;
• a first pair of polymeric sleeves each having a refractive index numerically lower than the refractive index of said exterior surface of said core and each possessing an inner surface disposed around and directly bonded respectively to a portion of said exterior surface of said core adjacent each one of said pair of polished end surfaces from which the surrounding portions of said cladding and said jacket have been removed, an outer surface and a pair of annular end surfaces, one of which abuts a corresponding unremoved portion of said cladding and the other of which is substantially flush with the corresponding one of said pair of polished end surfaces;
• and
• a second pair of polymeric sleeves each being of greater longitudinal length than a corresponding one of said first pair of sleeves and each possessing an inner surface, a portion of which is disposed around and bonded to said outer surface of the corresponding one of said first pair of sleeves, an outer surface and a pair of annular end surfaces, one of which is substantially flush with the corresponding one of said pair of polished end surfaces and the other of which is adjacent another portion of said inner surface of said second sleeve which surrounds and is sealingly bonded to a selected portion of the exterior surface of said jacket whereby, the optical waveguide is environmentally sealed, the junctions between the cladding and the first pair of sleeves are strain relieved and each polished end surface is substantially centered and mechanically restrained from any motion relative to the outer surface of its corresponding second sleeve, all without substantial degradation of the light propagating capability of the waveguide.

A method for terminating an optical waveguide of the type formed with a glass fiber core possessing at least one terminal end and a substantially cylindrical exterior surface coated with a polymeric cladding having a refractive index numerically lower than the refractive index of said exterior surface of said core, which method comprise the steps of:

• removing a portion of said cladding adjacent said at least one terminal end thereby exposing a cylindrical portion of said exterior surface of said core;
• disposing a first sleeve about the exposed portion of said exterior surface of said core such than an annular end surface on said first sleeve abuts the unremoved portions of said cladding, said first sleeve being fabricated from a heat fuseable polymeric material having a refractive index numerically lower than the refractive index of said exterior surface of said core;
• positioning a second sleeve of heat shrinkable polymeric material telescopically over said first sleeve and a portion of said cladding;
• heating said first and second sleeves thereby causing said first sleeve to soften and fuse and said second sleeve to shrink radially urging said at least one terminal end of said core and said first and second sleeves into a contiguous bonded structure;
• allowing said contiguous bonded structure to cool;
• polishing said at least one terminal end of said core and said surrounding sleeves in a plane substantially perpendicular to the longitudinal axis of said core at said terminal end whereby, the junction between the first sleeve and the unremoved portion of the polymeric cladding is strain relieved and the polished end surface of the core is substantially centered and mechanically restrained from any motion relative to the outer surface of the second sleeve, all without substantial degradation of the light propagating capability of the waveguide.

A method for terminating an optical waveguide of the type formed with a glass fiber core possessing at least one terminal end and a substantially cylindrical exterior surface coated with a polymeric cladding having a refractive index numerically lower than the refractive index of said exterior surface of said core, which method comprises the steps of:

• removing a portion of said cladding adjacent said at least one terminal end thereby exposing a cylindrical portion of said exterior surface of said core;
• disposing an article comprising a first sleeve and a second sleeve prebonded together, the first sleeve being about the exposed portion of said exterior surface of said core, such that an annular end surface on said first sleeve abuts the unremoved portions of said cladding, said second sleeve being telescopically disposed over a portion of said cladding, said first sleeve and said second sleeve being fabricated from a heat fuseable polymeric material having a refractive index numerically lower than the refractive index of said exterior surface of said core, and said second sleeve being fabricated if heat shrinkable polymeric material;
• heating said first and second sleeves thereby causing said first sleeve to soften and fuse and said second sleeve to shrink radially urging said at least one terminal end of said core and said first and second sleeves into a contiguous bonded structure;
• allowing said contiguous bonded structure to cool;
• and
• polishing said at least one terminal end of said core and said surrounding sleeves in a plane substantially perpendicular to the longitudinal axis of said core at said terminal end.