鎳擴散式鈮酸鋰脊型光波導之研製

Abstract

本論文主要是研究脊型光波導，以質子交換濕式蝕刻法，在鈮酸鋰基板上製作，此脊型結構適合用來製作各種光波導元件，因其表面非常平整光滑，而且可增加調變電場與光場的重疊積分值、改善光波與微波間相位不匹配的問題、降低波導與波導之間的耦合等優點。本實驗使用自動對準脊型蝕刻製程，此製程具有先擴散再蝕刻製程的特性，亦即只需對一道光罩；同時又具有先蝕刻再擴散製程的特性，即訊號傳輸時能量損耗較低。經由這樣的方法，相較於其他兩種製程製作出的脊型結構，其側壁會比較垂直。本論文對整個製作流程與原理提供完整的推導說明，且對脊型波導的蝕刻機制做深入研究，並提出可能遭遇的問題與解決方法。

This research is carried into ridge optical waveguide, which is produced on lithium niobate substrate in the way of proton exchange wet etching. Such ridge structure can well produce waveguide devices. Because its surface is smooth, and the way of production can increase overlap integral of electrical field modulation and optical field, hence to improves the problem of phase mismatch between microwave and optical wave, and to decrease coupling between waveguides. The experiment possesses the features of both diffusion prior to proton exchange wet etching fabrication process and proton exchange wet etching prior to diffusion fabrication process. In other words, self-aligned ridge optical waveguide fabrication process is employed by combing align one-time mask and low energy-losing in transparency. In this way, compared to the other two productions, the sidewall of ridge structure will be more vertical. To sum up, this article will provide complete introduction to whole production process, and make great efforts in the mechanism of ridge structure etching, also raises possible problems and practical solutions.