利用拉伸光纖製作光學可調低通濾波器之實驗與模擬

Abstract

在本論文中，我們說明有關用拉伸光纖作為光學可調的低通濾波器之模擬與實驗。在實驗上，我們利用單模的拉伸光纖(SMF-28:Corning)，並在其拉伸部份覆蓋厚厚的一層折射率匹配油(色散材料)。之後，利用溫度控制器去調光纖周圍折射率匹配油的溫度。我們觀察到，波長可調的範圍為1250 nm ~1650 nm，而其濾波效率為1 dB/nm，對溫度敏感程度為50 nm/□C，拒波程度可高達 50 dB。在模擬實驗上，我們利用R-Soft公司出版的BeamPROP 5.1這套軟體進行模擬。我們觀察到波在拉伸光纖中的傳播特性，並且討論波經過拉伸光纖後的功率、電場分佈型態、電場的等高線圖…等。最後，我們比較模擬上和實驗上的結果，並作結論。

In this thesis, we demonstrate both experimental and simulation results for optical tunable short-pass tapered fiber filters. In experiments, we use a single mode tapered fiber (SMF-28: Corning) coated with a dispersive optical material (Cargille index-matching liquid with the index nD=1.456 and dnD/dT of -3.74 □ 10-4/□C), which is either heated or cooled by a TE-cooler to achieve wideband tunable (1250 nm ~1650 nm) short-pass fused-tapered fiber filters with high cutoff efficiency (1 dB/nm slope) and to produce tuning slope and the optical rejection efficiency as high as 50 nm/□C and 50 dB, respectively. In simulation, we use the software called “BeamPROP 5.1” by “RSoft Design Group” to study the wave propagation in the tapered fiber and calculate the monitored power, mode profile, contour map…etc. Finally, we compare the experimental results with simulation results, and give a conclusion.