半导体调制器是光纤通信系统的核心器件之一，在高速率、大容量的光通信领域中起着举足轻重的作用。调制器的性能衡量指标包括插入损耗，半波电压及调制带宽等。减小调制器的插入损耗对于提升调制器在光通信系统中的应用性能有着至关重要的作用。调制器损耗的相当一部分来自调制器波导的模场与光纤的模场不匹配造成的耦合损耗。解决调制器与波导耦合的较好的方案是引入模斑变换器（Spot-size converter, SSC），以实现调制器波导与光纤的之间的模场匹配。本论文针对应用于III-V族半导体电光调制器模斑变换器的结构设计及制作工艺进行了研究。论文首先进行了两种基于导引层结构模斑变换器的设计。通过仿真优化确定了导引层的结构参数，并确定了两种优化模斑变换器的几何参数。同时同时对最优设计的光场，耦合损耗，对准容差进行了评估，确定基于混合型结构的模斑变换器（II型模斑变换器）具有更加优越的性能。为了实现II型模斑变换器，确定了基于模斑/衬底移动技术的光刻胶掩模制作方案。我们自行搭建了用于模斑/衬底移动技术的步进电机系统，以此实现了制备纵向结构的光刻胶掩模。据此我们初步确定了II型模斑变换器完整的制作工艺。

As essential devices in optical communication systems, semiconductor modulators are key ingredients when applied to high-speed，large bandwidth optical communication systems. General figure of merits to characterize the performance of a semiconductor modulator are insertion loss (IL), half-wave voltage and bandwidth. To reduce the insertion loss of modulators is of great importance in the improvement of figure of merits related to the modulators. In application, coupling loss between modulators and fibers contributes as a major part in the total insertion loss of semiconductor modulators. The coupling loss is caused by the mode mismatch between the waveguides of modulators and fibers. It is preferred to introduce spot-size converters (SSC) to reduce the mode mismatch between waveguides and fibers. The article is specified in the design and fabrication of SSCs for semiconductor modulators.We propose two kinds of spot-size converters based on guiding layer structure in this essay. Optimization of design parameters on guiding layer structures by simulation and calculation of optical field, coupling loss and alignment tolerance show that type II SSC exhibits better performance. We also build up a stepper motor controlling platform for the fabrication of photoresist mask. We succeed in fabricating photoresist mask for vertical structure, and propose a complete fabrication process for such SSCs.