改良式脊形電光調變器之研究

Abstract

本文提出一種新型的電極結構，此結構適用於X-cut鈮酸鋰基板上之脊形電光調變器，其優點為可增加重疊積分值、降低驅動電壓。經模擬分析，相較於傳統電極結構的脊形結構電光調變器，其驅動電壓可以降低15%以上，而且操作頻寬並未因而減少。且由模擬結果可以證明，將此結構應用在脊形側面傾斜的電光調變器，此優勢依舊存在。實驗上，亦應用此新型電極結構於脊形馬赫任德電光調變器之製作，量測結果顯示該元件訊熄比為18.5 dB，驅動電壓則由3.4V降至2.5V，極有應用價值。

A novel electro-optical (EO) modulator with ridge on the X-cut lithium niobate substrate is proposed. Its simulated driving voltage can be decreased more than 15% in comparison to that of a conventional one. The improvement of driving voltage and overlap integral is noticeable even when the side wall of ridge is tilted. For comparison, a Mach-Zehnder modulator with the improved EO modulator is successfully fabricated, whose measured extinction ratio is 18.5 dB and measured driving voltage is decreased from 3.4V to 2.5V. That is useful for practical application.