矽核光纖與玻璃光纖熔接方法之改善及矽核光纖在中紅外波段的折射率感測應用

Abstract

在本論文中，我們將矽粉填入玻璃管內，並以垂直抽絲法來製作矽核光纖(Silicon-Cored Fibers)。藉由優化抽絲的相關參數後，可以成功製作出約長1~2公尺長的矽核光纖，其纖衣與纖核的直徑誤差值分別控制在200±10μm與20±5μm左右，具有良好的均一性。由拉曼頻譜分析可知製作出的矽核光纖有著高純度和高度結晶的特性。 在本實驗室經由光纖抽絲塔抽出矽核半導體光纖後，在製作元件的過程中，半導體矽核光纖在連接一般單模光纖中本身會有熔接上的損耗，所以在併接的過程和方式是主要的關鍵，在此篇論文中就是利用我們所開發的一種新穎的熔接方式稱之為三環式電弧的熔接方法來連接單模光纖和矽核光纖，以降低熔接時所產生的熔接損耗，並同時與一般傳統的商用熔接機進行比較，證明此種三環電極放電式熔接法確實可以有效的降低異質光纖的熔接損耗。其中在同樣尺度的矽和光纖下，以三環式放電所得出之平均熔接損耗(Splicing Loss)為0.15~0.26dB，而相對用一般商用熔接機之平均熔接損耗為2.5~3dB左右。 最後應用方面，由於矽材料本身可以傳導到中紅外波段，故希望除了日後可以藉由我所製作的三環式放電結構來改善在中紅外傳輸時的熔接損耗外，還可以進一步得知在中紅外波段的感測效果，所以先以矽晶圓作為一個平台，作為未來可以在D型矽核光纖或矽核端面的前導，在實驗量測上，頻譜量測之共振位置和模擬有高度相似處，而其頻譜共振位置確實能隨著環境改變而飄移，穿透頻譜在折射率感測方面亦有良好的表現，其共振位置之靈敏度為1.61 nm / wt%。

Silicon-cored fibers were made by using a combined techniques of powder-in-tube and vertical-drawing. By optimizing the drawing parameters, 1~2 meters long silicon-cored fibers were successfully produced, and resultant silica cladding and Si core diameters being in the range of 200±10μm and 20±5μm. According to Raman spectrum analysis, the fabricated Si core is of high purity and high crystalline. Silicon-cored fibers, silicon-cored fiber usually suffered from large losses when spliced with a single mode or multi-mode fiber to make an optical device. Therefore, splicing method is crucial. We developed a new way called Tricyclic Fusion Method to splice a silicon-cored fiber and a silica fiber, which could lower the splicing losses. In addition, we compared to the normal commercial fusion splicer to prove that Tricyclic Fusion could effectively reduce the splicing losses between two different kinds of fiber. With the same diameter of silicon-cored fibers, the Tricyclic Fusion Method resulted in an average splicing loss 0.15~0.26dB, and the commercial fusion splicer with average splicing loss about 2.5~3dB. In the last application, because the silicon material can conduct to the mid-infrared range, we hope not only improve the splice loss by tricyclic fusion method in Mid-IR range but also can have a sensing application in Mid-IR range. By using silicon chip as a platform, it can as a precursor to D-shaped silicon-cored fiber and silicon end surface in the future. In the measurement, the resonance position of the spectrum is highly similar to the simulation, and its spectral resonance position is shift with the environment. The spectrum also performs well in refractive index sensing, and the sensitivity of the resonance position is 1.61 nm / wt%.