LiNbO3光纤型行波光调制器的有限元分析与设计

文中提出一种新型的LiNbO3行波光调制器——LiNbO3矩形光纤型行波光调制器，它用LiNbO3晶体光纤代替传统的LiNbO3波导，耦合效率高，调制带宽达500GHz，能保证很好的阻抗匹配和小驻波比。文中采用有限元法对调制器的尺寸形状进行模拟分析，并进行了优化设计，得到了最优化尺寸及其主要性能指标。最后，探讨了双电极LiNbO3矩形光纤型行波光调制器的制作工艺。

The Finite Element Analysis and Design of a Travelling-wave Optical Modulator Based on LiNbO3 Fibers

A novel type of LiNbO3 rectangular fiber travelling-wave optical modulator is presented in this paper, which replaces the traditional optical waveguides with specially-produced LiNbO3 rectangular fibers. It can not only greatly promote the coupling efficient with exterior fibers, but also make the velocity matching more easily to implement and expand the modulating bandwidth in result which reaches as far as 500GHz approximately, at the same time, the impedance of the modulator can also be perfectly matched with the microwave source and the load with an acceptable voltage standing wave ratio. The size of the structure is analyzed and designed by FEM, and the infinite boundary condition is approximated with far-field elements, which is proved to be more accurate than the direct truncation method. Then the electrodes are modified by adding two dielectric overlays on them, which is verified to be more efficient. In the end, the arts and crafts of the modulator are discussed.