The mathematical modelling of capillary drawing for holey fibre manufacture

The original publication can be found at www.springerlink.comMicrostructured optical fibres (i.e. fibres that contain holes) have assumed a high profile in recent years, and given rise to many novel optical devices. The problem of manufacturing such fibres by heating and then drawing a preform is considered for the particularly simple case of annular capillaries. A fluid-mechanics model is constructed using asymptotic analysis based on the small aspect ratio of the capillary. The leading-order equations are then examined in a number of asymptotic limits, many of which give valuable practical information about the control parameters that influence the drawing process. Finally, some comparisons with experiment are performed. For a limited set of experiments where the internal hole is pressurised, the theoretical predictions give qualitatively accurate results. For a much more detailed set of experiments carried out with a high-grade silica glass where no hole pressurisation is used, the relevant asymptotic solution to the governing equations is shown to give predictions that agree remarkably well with experiment.Fitt A.D., Furusawa K., Monro T.M., Please C.P. and Richardson D.J