Two-step manufacturing of hundreds of meter-long silicon micrometer-size core optical fibers with less than 0.2 dB/cm background losses

International audience; This work reports on the fabrication and the characterization of hybrid optical fibers with silicon core and silica cladding. Adopting a two-step manufacturing technique derived from the stack-and-draw method, silicon-core fibers with core dimensions ranging from about 0.8 mu m to 3.5 mu m have been successively drawn into hundreds of meter-long fibers. A 3.3 mu m diameter core fiber has been more extensively characterized and background losses for this as-drawn fiber are less than 0.2 dB/cm between 1250 nm and 1650 nm, with a minimum of 0.12 dB/cm around 1600 nm. The crystalline state of the core and the limited impact of oxygen contamination were confirmed by Raman scattering, x-ray diffraction, HR-STEM, and ToF-SIMS analysis. Transmission peaks associated with specific modal distributions are evidenced under certain injection conditions and their positions are shown to be in good accordance with mode cut-off wavelengths of a step-index silicon-core fiber.