A BiCore fibre (BCF) has been drawn and tested experimentally as a model for studying evanescent mode coupling to be used for single-mode passive fibre components made in the Fused-Head-End technique and in planar optics. The coupling coefficient K is shown to be linearly related to wavelength A. Polarization effects are manifested in the constant term only. Given the variation in core shapes good agreement with existing theory is found. A 167 mm long BCF forms a fibre polarization-splitter. For a BCF filter the figure of merit is the bandwidth length product, typically about 1.2 nm.m FWHM. Bending a BCF over a certain length and radius satisfies well straightforward theory so that the device can be fine-tuned in a controlled way. Some practical applications are indicated.
P. J. Severin,
"Evanescent-Mode Coupling In A Bicore Fibre: Experiments And Applications", Proc. SPIE 0949, Fibre Optics '88, (21 September 1988); doi: 10.1117/12.947538; https://doi.org/10.1117/12.947538