Micron-sized gold-nickel alloy wire integrated silica optical fibers
in: Optical Materials Express (2016)
Hybrid fibers are an emerging class of optical devices which allow integration of increasingly sophisticated functionality into fibers. Fibers containing metallic micro- and nanowires are particularly attractive considering their electro-optic functionality and their applicability in plasmonics. However, the use of pure metals intrinsically limits the available parameter space in terms of optical properties, mechanical stability, and chemical reactivity. In contrast, alloys can display synergistic properties of their metallic constituents, and can be tuned in terms of both optical and chemical properties. However, traditional alloy wire drawing processes yielding high aspect ratio alloy micro-wires are limited to wire diameters of the order of several tens of micrometers, and little is known about their optical properties. Here, we use pressure assisted melt filling to produce gold-nickel alloy micron sized wires with aspect ratios of 105 and diameters of 1.3 μm in silica optical fibers. We measure the modal loss of the hybrid fiber containing confined alloy wires, and show that it is comparable to the loss predicted by the alloy bulk permittivity. We also show that the alloy remains stable within the highly confined wire state even though, the bulk alloy exhibits a miscibility gap at room temperature. The fabrication technique and characterization procedure is a first step towards hybrid optical fibers containing longitudinal micron sized gold-nickel alloy wires and can be extended to a wide range of other alloys.