熔拉參數和色散機制對波長可調短通光纖濾波器之影響研究

Abstract

在本論文中我們利用熔拉技術來製作光纖濾波元件，透過將熔拉的區域浸於折射率匹配油(色散材料)內來完成波長可調短通光纖濾波器的實驗製作。利用溫度控制器控溫,可觀察到此濾波器對溫度的調變率為50nm/oc，濾波效率-1.2dB/nm，拒波效率達50dB。我們也使用模擬軟體模擬出各種熔拉參數對濾波器的影響，包括熔拉直徑、熔拉均勻長度、熔拉漸變長度等。根據實驗和模擬的對照，我們歸納了一組最佳的熔拉參數範圍。最後，我們將原先的單模光纖換為雙被覆層光纖來製作出新的光纖濾波器。由於雙被覆層光纖的外被覆層具有較低的折射率，根據色散機制可得知此濾波器可以有更佳的濾波效率，而我們在實驗和模擬上也都一致地證實這個效應的存在。

In the thesis, we demonstrate a new type of thermo-optic tunable short-wavelength-pass fiber filters (SPF) based on tapering standard single-mode fibers (SMF-28) to form fiber tapers, which are immersed in index matching liquids. Some of the significant results are the tuning efficiency can be 50nm/oc, the cut-off efficiency can be -1.2dB/nm and the rejection efficiency can be 55 dB. The effects of various taper parameters on SPF have also been investigated by simulation to determine the optimum parameter range. We have also demonstrated a new structure of widely tunable LP01-C tapered fiber filters with an even higher cutoff slope based on the tapered depressed-index outer ring fiber made from the double cladding fibers (DCLFs). The observed experimental results are explained by the dispersion mechanism and confirmed by theoretical simulation.