本論文主要研究利用光調控的液晶材料作為氮化矽環形共振腔的包覆層，利用照光的方式讓環形共振腔包覆層折射率改變，使共振波長位移，在使用上能做為可調式光開關的應用，內容分為兩個部分探討，第一部分研究氮化矽環形共振腔的基本光學特性，藉由量測環形共振腔的穿透頻譜結合數值擬合的分析方法，得到環形共振腔的能量耦合係數及光學損耗，我們可以分析不同的波導寬度隨著耦合間隙漸增，共振腔的品質、能量耦合係數、光學損耗如何變化，藉由實驗的結果有助於提升製作光學被動元件的品質。第二部分利用摻雜偶氮染料向列型液晶作為環形共振腔的包覆層，利用特定411nm波長的光引致偶氮染料的Trans-cis同素異構化效應，使得向列型液晶產生相轉變，從原來的液晶相轉變成同均相，進而導致包覆層的折射率變大，使共振波長移動，此外利用532nm波長的光可引致Cis-trans同素異構化而相轉變回原來的液晶態，並且讓共振腔的共振波長回到原來的位置。因此，利用此液晶的相態轉變特性，搭配環形共振腔可做為非易失性光開關的應用，我們也利用數值擬合法分析液晶環形共振腔的耦合係數、光學損耗以及探討液晶在光場下的行為表現。

This thesis is to study the effect of utilizing an optically tunable cladding material to externally change the resonance wavelength of a silicon nitride micro-ring device- thus produces an externally controlled/tunable optical switch. It is separated into two parts. The first part of the thesis will describe the fundamental optical properties of silicon nitride based (SiN based) ring resonator. The coupling coefficient and the optical loss in different gaps have been obtained by numerical fitting the transmission spectrum of the resonator. These properties are very useful to design the passive integrated photonics devices.
In the second part, we are going to discuss the ring resonator with azo dye-doped liquid crystal(LC) cladding. Azo dyes comprise two molecular configurations, the trans and cis forms. Upon purple irradiation (411nm), the trans isomers will transform to the bent cis isomers, at the same time, nematic liquid crystal will transform to isotropic state. On the other hand, a fast back-isomerization can be induced by applying green light (532nm), and at the same time, the state of the liquid crystal will return back to the nematic state. The phenomena is so-called photo-induced isomerization. Therefore, the refractive index of the cladding layer can be tuned by exposing the device to different lights.
The hybrid SiN- LC micro-ring resonator possesses the characteristics of a nonvolatile optically controlled switch. For a micro-ring in the add-drop multiplxer configuration and using a signal whose wavelength is at the resonance of the NLC state, the signal is directed to the drop port. When the device is illuminated by purple light, the device is turned to the PHI state and the signal is turned off from the drop port and this off state will last for hours without any sustain light (nonvolatile). The signal can be turned on to the drop port at any time by illuminating with a green light. It exhibits the potential to be used in signal processing elements with the advantages of ease of switching, long memory, and low power consumption. It therefore can be utilized as an optically activated nonvolatile switching element in optical integrated circuits.

第一章 緒論 1
1.1簡介 1
1.2論文概述 1
第二章 環形共振腔基本原理 3
2.1 環形共振腔簡介及特性 3
2.2光學損耗 5
2.2.1吸收損耗 5
2.2.2散射損耗 5
2.2.3輻射損耗 6
2.3 品質因子 8
2.4理論公式推導 9
2.4.1數值擬合公式推導 11
2.4.2臨界耦合 14
第三章 液晶基本原理 16
3.1液晶簡介 16
3.1.1何謂液晶 16
3.1.2液晶的分類 17
3.2液晶物理 18
3.2.1秩序參數 18
3.2.2液晶的光學異向性 19
3.2.3連續彈性體理論 22
3.2.4介電常數異向性 23
3.2.5液晶折射率與溫度關係 24
3.3 賓主效應 25
3.4 偶氮染料之光化學機制 26
第四章 實驗樣品裝備與量測方法 29
4.1 材料介紹 29
4.2 量測系統架設 34
4.2.1 量測流程 36
第五章 實驗結果與討論 40
5.1環型共振腔以空氣當包覆層的量測分析 40
5.1.1共振腔半徑40 於不同波導寬度與不同耦合間隙下以TM極化入射量測結果 40
5.1.2半徑40 於不同波導寬度與不同耦合間隙下以TE極化入射量測結果 51
5.2環形共振腔以摻雜染料液晶當包覆層的量測分析 59
5.2.1在R-POM下觀察光控試片的配向情形 60
5.2.2 光控試片照射雷射光後量測 61
5.2.3 光控試片於不同照射強度、時間下量測 64
5.2.4 光控試片回復時間量測 66
5.2.5光控試片穩定度測試 68
5.2.6環型共振腔以空氣當包覆層和以摻雜染料液晶當包覆層的能量耦合係數及光學損耗比較 71
第六章 結論 72
參考文獻 75

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