|Abstract: ||近年來,採用對稱型共面波導電極之鈦擴散 鈮酸鋰光調變器,已廣泛地被討論.此類光調變 器的調變頻寬及驅動電壓主要係受限於共面波 導電極的導體損失及微波與光波間的速度不匹 配.換言之,於鈮酸鋰光調變器中,共面波導電極 扮演一個非常重要的角色.另一方面,非對稱型 共面波導電極,於設計積體光學元件時,除能提 供額外的彈性,並能改善其性能.於本研究計畫 中,將針對具異向性基座、緩衝層及覆蓋導體之多層式非對稱型共面波導電極的各種微波特 性.換言之,推導所得解析式,將可做為鈮酸鋰光 調變器之電腦輔助設計工具.此外,針對具非對 稱型共面波導電極、緩衝層及覆蓋導體之鈮酸 鋰光調變器,將先解電場分布及電場與光場間 之重疊積分因數,接著探討其各種調變特性.於 分析過程中,將獲致設計鈮酸鋰光調變器之最 佳化條件,以改善其調變性能.|
Recently, the broadband optical modulator plays an important role in an ultracapacity and high-speed optical transmission system. The bandwidth of the optical modulator is restricted mainly by the conductor losses of the electrodes and the mismatch in velocity between microwaves and optical waves. In this project, the optical modulators with buffer layer, overlaid conductor and asymmetrical coplanar waveguide electrodes are studied to reduce the conductor loss and improve the phenomenon of velocity mismatch, and further providing low driving power and broadband operation. For the above optical modulators, the analytical formulas for the characteristic parameters are derived firstly and then used to study their microwave and optical modulation characteristics, including microwave effective index, characteristic impedance, conductor loss, driving voltage, modulation bandwidth, and figure of merit etc. The analysis results obtained in this project could be used as the guidelines in the design of optical modulators.