| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 103 === Single-crystal silicon-cored fibers were made by using a combined techniques of powder-in-tube and vertical-drawing. Much cheaper polycrystalline silicon powders substituting expensive single-crystal silicon powders or seed rods were packed into a fused silica tube. By optimizing the drawing parameters, meter-long silicon-cored fibers were obtained with ultralow transmission losses because the entire lengths of silicon cores were single crystalline. The Si-cored fibers were drawn with resultant silica cladding and Si core diameters being in the range of 100-300 microns and 10-30 microns, respectively.
We also demonstrated a fiber drawing system for fabricating Si cored tapered fiber. A fiber drawing system equipped with oxy-hydrogen flame and transition stage was used. According to the previously accumulated knowledge in fabrication of silica microfiber, we successfully fabricated Si cored tapered fibers with diameter of 2.6 microns in the waist section from an original Si-cored fiber with diameter of 20 microns.
Silicon microsphere resonators which exhibited high quality factor (Q) whispering-gallery-modes (WGMs) could be rapidly fabricated from Si-cored fibers using CO2 laser reformation. WGMs were excited by using the tapered silica fiber coupling technique, and a record resonant Q as high as 4 x 10^5 was obtained. The shift of resonant wavelength caused by thermo-optic effect of Si material was also observed.
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