超高雙折射差光子晶體光纖研究

光子晶體光纖作為新一代的光波傳輸介質，其應用涵蓋各重要領域，如光纖通訊、光纖感測、光顯示及生物醫學方面的應用。本論文主題一針對我們所提出之四種不同型態之光子晶體光纖，以有限元素法進行數值模擬分析，諸如調整缺陷周圍橢圓空氣孔長、短軸之比例關係、孔心距、纖衣之圈數與雙折射率間之關係。根據模擬結果顯示模型結構case A(纖核四周橢圓空氣孔尺寸相同)與case B(纖核上下2個橢圓孔面積為其它氣孔之0.5倍)之雙折射率差可達和。因橢圓形光子晶體光纖纖衣強烈的非對稱性，使其雙折射能達到10-2量級。主題二的部份針對長方形、橢圓形、菱形和圓形空氣孔，採矩形晶格排列的光子晶體光纖進行模擬分析。經模擬計算結果表明，採矩形晶格排列長方形空氣孔光子晶體光纖，有超高的模式雙折射，在λ=1.55μm達到8.1×10-2和損耗小於5×10-3(dB/km)。

關鍵字

雙折射；光子晶體光纖；有限元素法

並列摘要

Photonic crystal fibers (PCFs) have attracted a lot of research attention due to many possibilities and promising applications in communication and sensing. This thesis presents a numerical study of high birefringence induced by four types (Case A-B) of different sizes of elliptical air holes in tetragonal lattice photonic crystal fibers (PCFs). The numerical simulation is carried out by using the finite element method. The statistical correlations between the birefringence and the various parameters are obtained. Based on our results, two of our suggested structures, Case A and Case B, can considerably enhance the birefringence in PCFs, leading to values as high as 4.9×10-2 and 3.5×10-2, respectively. Because of elliptical air holes PCFs with cladding is to destroy the symmetry of the structure, and show that the birefringence can be as high as 10-2. Secondary, numerically investigate the rectangular lattice photonic crystal fibers (PCFs) with rectangular, elliptical, rhomboidal and circular air holes using a full-vector finite element method. Numerical results show that an extraordinarily high modal birefringence of proposed rectangular lattice PCF with rectangular air holes at λ= 1.55μm reaches 8.1×10-2 (which is the highest value to our knowledge) and the confinement loss is less than 5×10-3 dB/km, respectively.