The impact of capillary instability and furnace operating conditions on the fabrication of drawn metamaterials

Abstract

Metamaterials are composites containing metal structures imbedded within a dielectric matrix. Their nanoscale structure gives them optical properties that don’t exist in naturally occurring materials. This paper focuses on the issue of Plateau-Rayleigh instability when fibre drawing technology is used to manufacture such metamaterials. Linear stability analysis can identify the key operating parameters that influence the instability of the metal core as a function of the metal/dielectric combination used in the drawn fibre. To verify these theoretical predictions, a numerical fibre drawing model, developed using commercially available software, is used to examine the non-isothermal drawing of a polymer preform containing a concentric metal core in a cylindrical furnace. All heat transfer modes are included. To determine the external radiative heat flux across the preform surface, a Monte Carlo Ray-Tracing method is coupled with the drawing model to calculate the view factors between the furnace walls and the deforming preform. The impact of the key operating parameters on the drawing instability is numerically investigated with a simplified version of this heat transfer model. Optimized operating conditions that minimize drawing instability are proposed.