鈮酸鋰微碟形共振元件之研製

Fabrication of Microdisk Resonator on Lithium Niobate

范智彬(Chih-Bin Fan)

指導教授 ： 王子建

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2011年)

摘要

本論文在鈮酸鋰晶體上製作出具有底切碟形結構共振元件，藉由其橫向與縱向之高折射率對比，使其具更有效的光場侷限性，以降低光傳播時所造成的損失。底切蝕刻結構的製作是使用離子佈植與濕式蝕刻的技術來達成，製程上首先製作特定圖樣的鉻膜與光阻分別作為濕式蝕刻遮罩與離子佈植遮罩，然後佈植氦離子在鈮酸鋰晶體上，於特定深度產生晶格破壞，經由濕式蝕刻鈮酸鋰，可將鈮酸鋰下方的晶格破壞區移除而產生底切結構，利用此製程於實驗上製作出具有底切結構的微碟形共振元件。
濕式蝕刻鈮酸鋰-z面所產生的蝕刻面相當的粗糙，本論文使用了質子交換後短蝕刻及高溫熱處理方式改善晶片表面的平整度，前者是以質子交換增加鈮酸鋰晶格破壞以加快蝕刻速率，使基板表面粗糙部份優先蝕刻；後者以接近鈮酸鋰熔點溫度使表面鈮酸鋰輕微流動，藉由表面張力做自然修飾。高溫下鈮酸鋰鈮酸鋰會有氧化鋰外擴散發生，於熱處理時放置鈮酸鋰粉末來抑制氧化鋰外擴散。量測微碟形元件時使用錐形光纖來將雷射光耦合至共振腔中，本論文使用電熱法製作錐形光纖，利用電弧放電產生高熱使光纖軟化，並配合步進馬達拉伸使光纖拉細，量測時應用光場衰逝耦合至微碟形共振腔。

關鍵字

微碟形 ； 錐形光纖 ； 鈮酸鋰 ； 離子佈植 ； 濕式蝕刻

並列摘要

This thesis on the research of micro-disk resonator on lithium niobate with under-cut structure. With its horizontal and vertical high refractive index contrast, making it a more effective limitation of the light field in order to reduce light transmission caused by the loss.Under-cut structure is fabricated by using ion implantation and wet etching techniques to achieve, the process produced a specific pattern on lithium niobate. The chromium film and photoresist are used to wet etching and ion implantation mask respectively.By using helium ion implantation in lithium niobate crystal, it caused the lattice damage in particular depth. Then the wet etching of lithium niobate can remove the damaged area. Experimentally, we use this process to produce the micro-disk resonator device with under-cut structure.
It has certain amount roughness of surface in traditional wet etching. In this study,we use two technique a short etching of proton exchange and high-temperature heat treatment. The former is the proton exchange which increase lithium niobate crystal lattice damage. To increases the lattice damage will help to accelerate the etching rate, and the roughness of substrate is first etched. The latter is close to the melting temperature of lithium niobate. The surface of lithium niobate will reflow, so the surface tension help to do some modification. If lithium niobate with high temperature the lithium oxide will out-diffusion, we have to suppress it. We placed some powder of lithium niobate to suppress lithium oxide out-diffusion in heat treatment process. We use the tapered fiber to replace optical waveguide. In this paper, taper fiber produce as electro-heating method, heat generated by arc discharge soften the fiber and it will stretch by step motor.

並列關鍵字

micro-disk resonator ； lithium niobate ； ion implantation ； wet etching ； taper fiber

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