分析了厚電極厚緩沖層的共面波導Mach-Zehnder行波電極LiNbO3光調制器，討論了電極厚度和緩沖層厚度對調制器特性參數的影響，得到了調制器的有效折射率、特征阻抗、半波電壓及損耗系數等參數。通過對比分析，選擇合適的電極厚度和緩沖層厚度，優化調制器性能，近似滿足速度和阻抗匹配，實現了圖寬帶調制。
關 鍵 詞 共面波導; 保角變換; 速度匹配; 阻抗匹配; 寬帶光調制

Abstract The Mach-Zehnder traveling wave LiNbO3 optical modulator with thicker electrodes and relatively thicker SiO2 buffer layer have been analysed using conformal mapping, taking into account the dependence of the modulation characteristics on the thickness of electrodes and buffer layer at the same device. The relation between the parameters and the modulation characteristics, such as effective index, characteristic impedance, half-wavelength voltage and conductor loss, have been obtained to select the proper thickness of the electrodes and buffer layer to optimize the performance of the modulator. By using the calculation results, the velocity matching and impedance matching are achieved approximately to realize the broadband modulation.
Key words coplanar waveguide; conformal mapping; velocity-matching; impedance-matching; broadband optical modulation