Measurement of single-mode fibre core-cladding concentricity

Single-mode fibre core-cladding concentricity has been measured by using a fibre splicing technique. In this technique a short length of fibre is broken in two and one length is rotated about its own axis ¿ degrees with respect to the other length and then the two lengths are spliced together. The splice loss when ¿ = 180° is a direct measure of the fibre butt-joint offset and hence also of the concentricity of the core and the cladding. A submicrometre sensitivity for this measurement has been achieved.