Reactive molten core fabrication of silicon optical fiber

Silicon optical fibers fabricated using the molten core method possess high concentrations of oxygen in the core [Opt. Express 16, 18675 (2008)] due to dissolution of the cladding glass by the core melt. The presence of oxygen in the core can influence scattering, hence propagation losses, as well as limit the performance of the fiber. Accordingly, it is necessary to achieve oxygen-free silicon optical fibers prior to further optimization. In this work, silicon carbide (SiC) is added to the silicon (Si) core to provide an in situ reactive getter of oxygen during the draw process. Scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and powder x-ray diffraction (P-XRD) are used to verify that the glass-clad silicon optical fibers possess very low oxygen concentrations and that the SiC is consumed fully during the reactive molten core fabrication. Optical measurements indicated a reduction in light scattering out of the silicon core as expected. However, the measured attenuation of about 10 dB/cm, which is consistent with existing low-oxygen-content silicon fibers, implies that scattering might not be the dominant source of loss in these molten core-derived silicon fibers. More generally, this work shows that the high temperature processing of optical fibers can be an asset to drive chemical reactions rather than be limited by them. (C) 2011 Optical Society of America