鈮酸鋰藍光波導元件之研製

Design and Fabrication of Lithium Niobate Blue-Laser Waveguide Devices

李牧家(Mu-chia Lee)

指導教授 ： 王維新

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01456

摘要

由於半導體技術的進步，使得本來並不常見的藍光雷射可以成它a積體化而製作在晶片上，也使得釵h本來受限於波長因素的元件應用得以實現。在其中，藍光波段下的光通訊系統也有在軍事和商業上的應用價值，因此其光通訊元件之研究與製作亦為重要之課題。
在本論文中，重點即在於將原本應用在光纖通訊系統上的積體光學元件如光波導以及電光調變器，推廣到藍光波段的光通訊系統上；其中，使用鈮酸鋰晶體作為元件的材料可以有效的應用其光穿透範圍，電光效應以及耐用性。在此情況下，對於波導的單模態考慮，短波長時容易產生的外擴散問題，以及光折效應，本論文中都將加以探討；並對此分別提出以鈮酸鋰粉末搭配溫度控制來抑制外擴散，以及使用元件為馬赫任德形式，而非方向耦合形式來避免光折效應的方式解決。
本論文的實驗成它a製作出藍光波段下的單模態光波導和馬赫任德式電光調變器，與模擬的結果相互比較，發現波導線寬實際上略大於模擬結果。馬赫任德調變器在藍光波段之下的調變效果為：在電極長度8mm之下，操作電壓為9伏特，訊熄比約為8.5dB，此亦為目前鈮酸鋰馬赫任德電光調變器在藍光波段作調變的首次結果。

關鍵字

鋰離子外擴散 ； 馬赫任德調變器 ； 鈮酸鋰 ； 單模態 ； 光波導 ； 藍光

並列摘要

Blue laser can now be successfully integrated on a chip because of the great advance on semiconductor fabrication technology. Devices for potential application at this wavelength can thus be realized. Among them, optical communication system at blue laser wavelength is quite unique for both military and commercial uses. The study of devices in this system is then becoming important.
In this thesis, optical waveguides and electrooptic(EO) modulators at blue laser wavelength, instead of commonly used 1.55µm are studied. Lithium niobate was used as waveguide material because of its durability, optical transparency, large electrooptic coefficients, and strong nonlinearity. Moreover, the problems of narrower single mode waveguide width, more serious lithium outdiffusion, and stronger photorefractive effect are carefully studied and solved.
Single-mode waveguides were first fabricated to obtain appropriate process parameters. Then, Mach-Zehnder modulators are fabricated for studying EO modulation. Upon comparison, it is found that the linewidth of single mode waveguide is wider than that simulated using the index extrapolated from the long-wavelength model. The lithium niobate Mach-Zehnder modulator was modulated at blue laser region, and is found to have a halfwave voltage of 9V and an extinction ratio of 8.5dB. To our knowledge, those are the first reported data, so far.

並列關鍵字

Mach-Zehnder ； lithium niobate ； waveguide ； single mode ； EO modulator ； blue laser ； lithium outdiffusion

參考文獻

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