傳統的光子晶體光纖在製作完成後，便難再利用外在因素調變其光學特性，因此有人提出在光子晶體光纖的空氣孔洞內填入可調性材料，如：液體與液晶，來製作可調式光子晶體光纖元件。在本論文中，我們利用液體填充光子晶體光纖與光控液晶光子晶體光纖來製作新型可調式光子晶體光纖元件。首先，我們利用真空注入技術將兩小段液體填充至光子晶體光纖孔洞內，成功地製作出一種新穎且不需破壞光纖外在結構的液體引致馬赫-任德光子晶體光纖干涉儀。量測結果發現可以得到明顯的干涉條紋，並且干涉儀的消光比在波長1525 nm時約為-15 dB。此外，我們所製作的馬赫-任德干涉儀對溫度與彎曲敏感度分別為：-176 pm/oC和15.5 nm/m，其溫度和彎曲的高敏感度顯示了此液體引致馬赫-任德光子晶體光纖干涉儀具有應用在光纖感測器的能力。
另外，我們將向列型液晶與光控染料4MAB所組成之光控液晶混合物填注入光子晶體光纖中形成光控液晶光子晶體光纖。將光控液晶光子晶體光纖串聯一般液晶光子晶體光纖可以製作出光調控帶通濾波器。利用照射5秒藍光雷射，可以看到兩個可調控傳輸頻帶各自有115 nm與110 nm之頻寬變化，而傳輸頻帶中心波長的位移變化量分別為48 nm和43 nm。接著，我們在光控液晶光子晶體光纖內摻雜銀奈米粒子以改善其反應時間，量測結果顯示，上升時間與下降時間分別可以減少38%和42%。
最後，我們也利用選擇性封孔技術將光控液晶混合物選擇性地填注入光子晶體光纖之兩側空氣孔洞，製成可調式光控液晶光子晶體光纖衰減器。利用照射藍光雷射，在波長為1100 nm處可得到-26 dB的傳輸衰減。我們所製作的光控液晶光子晶體光纖衰減器也可以藉由照射綠光雷射來回復其傳輸特性，形成有用的光調控元件。

As the photonic crystal fibers (PCFs) are fabricated, it is hard to modulate their optical properties to function as tunable optical devices. To introduce tunable optical properties into the PCFs, one can infiltrate tunable-index materials, such as liquid and liquid crystals (LCs), into the air holes of the PCFs to form tunable optical devices. In this dissertation, we employ liquid-filled PCFs and photoresponsive PLCFs to form novel tunable optical devices. First, we utilize a vacuum pumping machine to infiltrate two liquid sections into the PCFs. A novel Mach-Zehnder interferometer (MZI) with two liquid sections can be successfully fabricated. Unlike other PCF-based MZIs, no damage is made to the PCF structure during the fabrication of our proposed MZI structure. The experiment results show that very clear interference patterns can be obtained, and a extinction ration (ER) of -15 dB can be achieved at λ = 1525 nm. Besides, the temperature and bending sensitivities of our fabricated PCF-based MZI are -176 nm/oC and 15.5 nm/m, respectively. As a result, our fabricated PCF-based MZIs can be utilized in temperature and bending sensing applications.
We have also fabricated photoresponsive PLCFs by infiltrating a LC mixture consisting of E7 LCs and the photoresponsive 4MAB into PCFs. By seriesly connecting a photoresponsive PLCF and a PLCF filled with E7 LCs, an optically tunable bandpass filter can be realized. After 5-second blue-laser irradiation, the bandwidth variations of two pass bands are 115 nm and 110 nm, respectively, and the center wavelengths of the transmission bands are shifted about 48 nm and 43 nm. In addition, we dope the Ag NPs into the photoresponsive PLCFs to improve the response time. The measurement results show that the rise time and decay time can be reduced about 38% and 42%, respectively.
Finally, a selective blocking technique is used to infiltrate the photoresponsive LC mixture into both-side air holes of the PCFs to from optically tunable PLCF attenuators. By irradiating a blue laser, a maximum attenuation tunability about -26 dB can be obtained at λ = 1100 nm. Our fabricated optically tunable PLCF attenuators possess reversible properties by green-laser irradiation and can be applied in optical tunable devices.

1 Introduction 1
1.1 Photonic Crystal Fibers……………………………………………1
1.2 Liquid-Filled Photonic Crystal Fibers……………………………4
1.3 Photonic Liquid Crystal Fibers……………………………………7
1.4 Mativations and Organization of the Dissertation………………10
2 Basic Properties of Nematic Liquid Crystals 28
2.1 Optical Properties of Nematic Liquid Crystals…………………28
2.1.1 Birefringence……………………………………………29
2.1.2 External Electric Field Effects for NLCs…………………31
2.1.3 Order Parameter and Temperature Effects for NLCs………32
2.2 Photoresponsive Azobenzene-Doped Nematic Liquid Crystals…33
3 Sample Preparations 44
3.1 Overview…………………………………………………………44
3.2 Fabrication of Photonic Crystal Fiber Devices…………………44
3.2.1 PCF-Based MZI (Used in Chapter Four) …………………44
3.2.2 Photoresponsive PLCFs (Used in Chapter Five) …………47
3.2.3 Photoresponsive PLCFs Doped with Ag NPs
(Used in Chapter Five) ………………………………49
3.2.4 Selectively Blocking Technique (Used in Chapter Six) …51
4 Mach-Zehnder Interferometer Based on Selectively
Liquid Infiltration in Photonic Crystal Fibers 68
4.1 Operation Machanism of PCF-Based MZIs………………………69
4.2 Optical Properties of PCF-Based MZIs………………………72
4.3 Measurement for Temperature Sensitivity………………………76
4.4 Measurement for Surrounding Refractive Index Sensitivity……77
4.5 Measurement for Bending Sensitivity………………………79
4.6 Liquid Length Effect for Temperature Sensitivity………………80
5 Photoresponsive Photonic Liquid Crystal Fibers 101
5.1 Optical Properties of Photoresponsive PLCFs………………102
5.1.1 Irradiation Effects of Photoresponsive PLCFs……………102
5.1.2 Temperature Effects of Photoresponsive PLCFs…………103
5.1.3 Thermal Recovery of Photoresponsive PLCFs……………105
5.2 Optically Tunable Bandpass Filter Using Series-Connected
PLCFs……………………………………………………………106
5.3 Response Time of Photoresponsive PLCFs Doped with
Ag NPs…………………………………………………………108
6 Optically Tunable Selective-Filled Photoresponsive Photonic
Liquid Crystal Fiber Attenuators 128
6.1 Fabrication of Optically Tunable PLCF Attenuators……………128
6.2 Optical Tunable PLCF Attenuator………………………………131
6.3 Polarization Properties of Optically Tunable PLCF
Attenuators………………………………………………………133
7 Summary and Conclusions 147

References 150
Publication

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