Gooch and Housego Plc

Adrian Norman

Norman Fisher

Thomas Legg

A method of free space fiber-to-fiber coupling includes providing a first optical fiber and a second optical fiber spaced apart from one another by a free space distance having a pair of spaced-apart achromatic collimating lenses within the free space distance. Essentially single mode light is launched from the first fiber at a wavelength &#x3bb; or a range of &#x3bb;s that provides at least a portion of its light at wavelength(s) below a cut-off wavelength for the first fiber. The first optical fiber and second optical fiber are both &#x3c;50 m and sufficiently short to provide essentially single mode operation. The essentially single mode light after the launching propagates as free space light through said free space distance and is received by and propagates in the second optical fiber as essentially single mode light.

Free space fibre-to-fibre coupling using optical fibres below cut-off

An optical fiber device includes a first optical element for transmitting light. An output fiber includes an output fiber core having a light receiving end optically aligned to receive light from the first optical element, and includes at least a first outer cladding on a clad portion. The output fiber includes a mode stripper adhesive with a first adhesive composition and a structural adhesive with a second adhesive composition thereon. The mode stripper adhesive is positioned closer to the first optical element than the structural adhesive to strip a majority of power of cladding guided mode(s) light before reaching the structural adhesive. The mode stripper adhesive has a lower hardness as compared to the structural adhesive, and is substantially indexed matched to an outermost layer of the output fiber that it is in direct contact with.

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Plymouth, United Kingdom

Adrian Norman