使用矽核光纖製作矽微米球與其在溫度與折射率感測之應用

Abstract

在本論文中，我們將粉末填入玻璃管內，並以垂直抽絲法來製作矽核光纖(silicon-cored fibers)。我們使用成本便宜許多的多晶矽粉取代成本高昂的單晶矽棒或晶種來製作矽核光纖。藉由優化抽絲的相關參數後，可以成功製作出長達數公尺的矽核光纖。最後抽出來的矽核光纖玻璃層直徑100-300微米、矽核心直徑10-30微米。由能量散佈分析儀可知製作出的矽核光纖有著高純度的特性。由拉曼、X光散射儀可知矽核光纖有著高度結晶的特性。由背向散射電子繞射儀分析得知其單晶的長度可維持超過100微米。 我們將矽核光纖以電弧平移台拉絲來進行二次抽絲，可製作出矽核椎狀光纖，已成功將原尺寸約20μm的矽核直徑抽細至2.9μm。 我們使用電弧加熱一段矽核光纖並同時控制緩慢進出料以製作一連串矽微米球，並將矽微米球置入單模光纖和中空光纖熔接後的空腔中製作光纖探針感測器，其感溫靈敏度約80pm/℃，最高感溫到700℃。除此之外，該開放式的架構也能進行酒精濃度的折射率液體量測，藉由快速傅利葉轉換分析得其靈敏度為-5.326±0.223/RIU。

Silicon-cored fibers were made by using a combined techniques of powder-in-tube and vertical-drawing. Much cheaper polycrystalline Si powders substituting expensive single-crystal Si powders or seed rods were packed into a fused silica tube. By optimizing the drawing parameters, several meters long silicon-cored fibers were obtained. The silicon-cored fibers were drawn with resultant silica cladding and Si core diameters being in the range of 100-300 m and 10-30 m, respectively. According to energy-dispersive x-ray spectroscopy, the fabricated Si core is in high purity. From Raman spectrum and X-Ray diffraction analysis, the silicon-cored fiber is high crystalline. The single crystalline property of silicon-cored fibers could continue for more than 100 m long according to electron backscatter diffraction analysis. We also demonstrated a fiber drawing system for fabricating tapered silicon-cored fiber. A fiber drawing system equipped with arc discharges and motorized translation stage was used. We successfully fabricated tapered silicon-cored fibers with diameter of 2.9 μm in the waist section from an original SCF with diameter of 20 μm. We heated a silicon-cored fiber to produce silicon microspheres sequentially by arc discharges. By tuning the splicing current parameter, SCF was slowly heated by arc discharging. And a silicon microsphere thus obtained was put in a hollow core fiber spliced with a single mode fiber to form a temperature fiber sensor. The measured thermal sensitivity was ~80pm/℃ for temperature range up to 700℃. The thermal sensitivity was about five times higher than those of silica fiber based. The structure could allow direct contact with an external environment, the fiber probe could also serve as a refractive index sensor with a sensitivity about -5.326±0.223/RIU.