- 學位論文
提昇鈮酸鋰微碟形元件共振特性之研究
Enhancement of Resonant Properties of LiNbO3 Microdisk Devices
摘要
本論文研製具有縱向高折射率對比、高品質因子之鈮酸鋰微碟形元件，並量測分析其共振特性。在元件製作上，使用離子佈植與濕式蝕刻在鈮酸鋰-z面上製作出具有底切結構之微碟形元件，此結構具有橫向與縱向高折射率對比，使光場能完全侷限在共振腔中，降低光傳播時所造成的散射與輻射損失。實驗中使用表面熱流處理製程，以接近物質熔點的高溫使材料表面具流動性，藉由表面張力而達到自然修飾表面結構之目的，如此可減少由於蝕刻過程所造成的粗糙表面與不平整圖樣邊緣，降低元件表面的散射損耗，提昇元件的共振特性。微碟形元件的量測使用錐形光纖耦合法進行光耦合，極細的錐形可使得光纖中的傳輸光場具有延伸至自由空間程度較大的衰逝場，提昇耦合的效率。實驗中使用錐形光纖分別對未熱流與熱流3小時之直徑20μm微碟形元件進行耦合傳輸頻譜量測，未熱流之微碟形元件的FSR約為15.9nm、品質因子為4565；而熱流3小時之微碟形元件的FSR約為15.6nm、品質因子為18601。實驗結果顯示，所製作的鈮酸鋰微碟形元件具有高達104的品質因子，未來可進一步結合鈮酸鋰優良的電光與非線性光學效應，製作高效能的鈮酸鋰微碟形共振元件。
並列摘要
In this work, we fabricated LiNbO3 microdisk devices, which have high refractive index and quality factor, we also measure and analyze the characteristic of resonance. The –z face under-cut structure is fabricated by using ion implantation and wet etching techniques to achieve, its horizontal and vertical high index contrast, making it a more effective limititation of the light field in the resonator, reducing the scatter and radiation loss when light transmission. In the experiment, we can enhance the resonantor’s characteristic and lower the scatter loss of the device by use the surface thermal reflow process, approaching the melting temperature of the lithium niobate, making the surface more smoothly. In this way, we can reduce the roughness surface and irregularity pattern boundary, which is cause by wet etching. The thin region of the fiber taper is, the strong the evanescent field extend, which can elevate the coupling efficiency. By using the strong evanescent field in the tapered region we can couple it to micro disk. In the thesis, coupling to micro disk with 20μm diameter, thermal reflow non-thermal reflow and three hours separately, in non-thermal reflow we can get the FSR about 15.9nm, quality factor 4565,in thermal reflow three hours we can get FSR about 15.6nm, quality factor 18601.As shown the result, our lithium niobate micro disk have quality factor high as 104. In the future we will combine the electro-optic and nonlinear optic effect, fabricating high effective lithium niobate micro disk resonance device.