Analysis of Capillary Instability in Metamaterials Fabrication Using Fiber Drawing Technology

Plasmonic metamaterials are composites containing metal structures imbedded within a dielectric matrix. Their nanoscale structure gives them optical properties that can be nonexistent in naturally occurring materials. However, the requirement for a subwavelength structure creates difficulties when fiber drawing technology is used to fabricate such metamaterials due to Plateau-Rayleigh instability effects. This paper addresses the instability issues by combining classic linear stability analysis with scaling considerations for the drawing of a fiber containing a concentric metal core. In terms of the amplitude growth of radial fluctuations, the key operational parameters that influence metal core instability are identified as a function of the metal/dielectric combination, while instability growth is correlated with three dimensionless numbers. To verify these theoretical predictions, a numerical fiber drawing model, developed using a commercial software package (PolyFlow), is employed to simulate the nonisothermal drawing of a polymer preform containing an indium metal core in a cylindrical furnace. Together, these theoretical predictions and numerical simulations provide key insights into conditions that minimize the instability of drawn fiber-based metamaterials for optical applications.