Study of optical fibre structures by Atomic Force Microscopy

A novel method using atomic force microscopy (AFM) to study optical fibre structures at the fibre end-face has been successfully developed. The doping concentration profiles of fibres revealed by differential etching speeds in a saturated solution of ammonium bifluoride at room temperature (25°C) were obtained from AFM topographic images. The superior spatial resolution of AFM made it possible to resolve concentric structures a hundred times smaller than the feature, due to the difference in the known refractive index (?n) of 1 × 10-3. Fibres with small core diameters and anisotropic structures, such as polarization-maintaining fibres, were studied with ease. © 1996 Chapman & Hall.