基于直线法分析设计的新型Mach-Zehnder型GaAs高速行波光调制器

New Designed Mach Zehnder GaAs Traveling wave Interferometer Modulators Based on the Analytical Numeral Results of the Method of Line

本文首次提出利用ｎ＋ 重掺杂层的慢波效应研制 Ｍａｃｈ Ｚｅｈｎｄｅｒ 干涉型行波光调制器，并通过在介电常数εｒ 中引入与电导率有关的虚部σ／ωε０，拓展了直线法对介质损耗的计算，从而就该调制器的各结构参数对其微波特性的影响进行了详细的理论分析计算。由此我们确定了可以同时达到光波与微波速度匹配且损耗最小的器件设计参数，其理论带宽可达３０ Ｇ Ｈｚ。然后在理论分析结论的基础上提出了改进的优化结构，通过在 Ｍ Ｚ型调制器的两个光波导之间挖槽，突破了传统 Ｍ Ｚ结构中电极间距的严格限制，达到缩小电极间距，减小光波导层厚度的目的，进而使理论带宽大幅提高，为研制工作奠定了基础。

A new design of Mach Zehnder traveling wave interferometer modulator based on the slow wave effect of the n +heavy doped epitaxial layer are proposed the first time in this paper.When applying the method of line to finite conductivity structure,the permittivity of semiconductor is assumed to be complex.The influences on the microwave characteristics of the structural parameters of the modulator are analyzed in details by means of the method of line.Based on the analytical results,we get the structural parameters which is needed so as to obtain velocity match and the minimum loss.Its 3dB bandwidth is estimated around 30 GHz.We also propose a new optimal grooved structure,which can reduce the gap of electrodes and the thickness of waveguide,so as to make the modulator's 3 dB bandwidth to be expanded largely.