Huntington, Shane TAshby, SElias, Merrill FLove, John2015-12-132015-12-130013-5194http://hdl.handle.net/1885/93989The geometrical shape and refractive index profile of the cores of fused-taper fibre couplers made by the heating, fusing and tapering technique have been measured to an accuracy of better than 10 nm. This approach involves precision cleaving, hydrofluoric acid etching and atomic force microscope (AFM) measurement. Results reveal that the core profile and cross-sectional geometry along the taper differ significantly from the normal assumption of scaled circular cores.Keywords: Atomic force microscopy; Etching; Hydrofluoric acid; Refractive index; Fused taper fiber couplers; Optical fiber coupling200010.1049/el:200001882015-12-12