光子晶體光纖是由空氣孔洞在光纖纖殼部份做週期性的排列所組成，當它被製作完成之後，就很難再利用外在因素去調變其光學特性。利用在光子晶體光纖的空氣洞中填充液體，可以製作可調式光纖元件，但是液體層會增加光纖的傳播損耗。在本論文中，我們提出了一個簡單的選擇性封孔技術，並且結合真空吸引的步驟，成功地製作了內層液體填充的光子晶體光纖。藉由液體層外的空氣孔洞，傳播損耗可以有效地被減小，並且保有溫度調變的特性。我們同時也製作內層液晶填充的光子晶體光纖，除了保持損耗降低的特性之外，電場跟溫度調變的能力也還是存在。
另外，我們也提出了在光子晶體光纖中以非對稱的方式填充液體，製作可調式的雙折射性液體填充光子晶體光纖。對該光纖我們分別作了遠場以及極化相依損耗的量測。因為其不對稱結構，量測到的模態場形是橢圓形狀。而相較於傳統的極化維持光纖，我們提出的雙折射性液體填充光子晶體光纖在波長1547.8nm時，可達到 2.89×10-3的高雙折射性，並且極化相依損耗也明顯大於傳統極化維持光纖。此外，我們將此雙折射性液體填充光子晶體光纖結合光學干涉迴路，應用在溫度的感測，可以成功得到-2.12 nm/°C的高靈敏度，這個值是大於由傳統雙折射光纖組成的干涉感測器。

Photonic crystal fibers (PCFs) are fabricated in silica with air holes running along the entire fiber in the fiber cladding. The geometric parameters of the PCFs are fixed and it is hard to modulate their optical properties. By infiltrating index-tunable liquids into the air holes of the PCFs, we can obtain liquid-filled PCFs which can function as tunable optical devices. But the losses become large due to the lossy liquid-hole layers. In this thesis, we use a simple selectively blocking technique and the vacuum filling method to fabricate internally liquid-filled PCFs. From the measured results, the propagation losses of the internally liquid-filled PCFs can be efficiently reduced, and the thermal tunability is still maintained. Besides, we also fabricate internally liquid-crystal-filled PCFs. Not only the thermal tunability but also the electrical tunability can be retained of the loss-reduced internally LC-filled PCFs. The electrical tunability can be induced by applying an external electric field. As the applied voltage reaches 200 V, we can obtain the splitting effect of the transmission band.
By using the selectively blocking technique, we also fabricate birefringent liquid-filled PCFs by asymmetrically infiltrating the liquid into the unblocked air holes. An elliptical far field can be observed for our sample. In addition, the measured polarization dependent loss (PDL) is larger than 2 dB. Compared with traditional PMFs, our fabricated sample has larger PDL values and birefringence. The measured birefringence is as high as 2.89×10-3 at 1547.8 nm. Besides, a temperature sensor consisting of a Sagnac loop interferometer (SLI) and our fabricated birefringent liquid-filled PCF is demonstrated. The linear sensitivity is -2.12 nm/°C which is larger than that of other PMF-based SLI sensors.

1 Introduction 1
1.1 Photonic Crystals ................................................................................... 1
1.2 Photonic Crystal Fibers.......................................................................... 2
1.3 Liquid-Filled Photonic Crystal Fibers.................................................... 3
1.4 Chapter Outline ...................................................................................... 5
2 Fabrication of Selectively Liquid-Filled Photonic
Crystal Fibers 13
2.1 Overview.............................................................................................. 13
2.2 Internally Liquid-Filled PCFs .............................................................. 13
2.2.1 Selectively Blocking Technique.................................................. 14
2.2.2 Vacuum Filling Method............................................................... 16
2.3 Birefringent Liquid-Filled PCFs .......................................................... 17
3 Measurement of Internally Liquid-filled Photonic
Crystal Fibers 28
3.1 Measurement Setup.............................................................................. 28
3.2 Thermal Tunability of Internally Liquid-Filled PCFs.......................... 29
3.3 Thermal and Electrical Tunability of Internally LC-Filled PCFs ........ 31
4 Measurement of Birefringent Liquid-Filled Photonic Crystal
Fibers 43
4.1 Overview.............................................................................................. 43
4.2 Sagnac Fiber Loop Interferometer ....................................................... 44
4.3 Birefringent Liquid-Filled PCFs .......................................................... 45
4.4 Temperature Sensing............................................................................ 48
5 Conclusion 62
Bibliography 64

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