以混合酸質子交換濕式蝕刻法研製鈮酸鋰脊形光波導

Fabrication of Lithium Niobate Optical Ridge Waveguides Using Mixed-Source Proton-Exchange Wet-Etching

曾瑋驊(Wei-Hua Tseng)

指導教授 ： 王維新

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.00821

摘要

本論文以探討焦磷酸混合己二酸在鈮酸鋰基板上進行質子交換，再配合濕式蝕刻方式在鈮酸鋰上製作脊形光波導元件。在製程方面，先嘗試不同的質子交換溫度和時間，再用氫氟酸和硝酸的混合液進行濕式蝕刻，以製作出脊形結構。
接著用掃描式電子顯微鏡觀察脊形的斷面，量測脊形的高寬比。此外，再用原子力顯微鏡對蝕刻後的平面進行掃描，以確認本文提出的質子酸源所造成的表面粗糙度仍適用於製作光通訊元件。
光學量測方面，則先製作具有脊形斷面的S 形彎曲波導，量測其傳輸率，觀察脊形結構對光的侷限性，以證明所製作的脊形能增加光的傳輸能力。此外，亦針對直波導使用逆切法，來量測波導的傳輸損耗，並將量測結果與表面粗糙度、傳輸率作比較，以確認其關聯性。

關鍵字

鈮酸鋰 ； 脊形光波導 ； 積體光學 ； 質子交換 ； 溼式蝕刻

並列摘要

Mixed pyrophosphoric acid and adipic acid are used as the solution for protonexchange in LiNbO3. For testing, the proton exchanged areas are obtained by using various temperatures and times. Then, the exchanged areas are wet etched with mixed hydrofluoric acid and nitric acid to reveal ridge structures for optical waveguide devices.
Scanning electro microscopy is then used to investigate the end faces of the ridge structures and measure the aspect ratios. Moreover, the etched surfaces are scanned by atomic force microscopy to make sure if the overall roughness is small enough for the fabrication of devices for optical communication.
For optical characterization, ridge-type S-bend waveguides are fabricated for measuring the transmission ratios to confirm the optical confinement of ridge structures, experimental results show that the steeper ridge structure fabricated by the proposed proton-exchange source can give rise to larger optical transmission ratio.Moreover, the optical transmission loss is measured by the cut-back method to study the effect of surface roughness on the transmission ratio.

並列關鍵字

lithium niobate ； optical ridge waveguide ； integrated optics ； proton exchange ； wet etching

參考文獻

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