提出了一种基于光子晶体和纳米线波导的马赫-曾德尔型调制器.该调制器由硅基光子晶体平板波导、纳米线波导和光子晶体多模干涉耦合器(MMI)构成。在光子晶体与纳米线波导连接处采用了锥型结构，用于减少模式失配造成的损耗。利用时域有限差分法(3D-FDTD)进行仿真分析，结果表明，该调制器在工作波长1550 nm下的插入损耗为0.3 dB，消光比为15.1 dB，器件尺寸仅46 μm×8 μm×0.22 μm，调制带宽可以达到68 GHz，且工作区域覆盖了以1551 nm为中心波长20 nm的通信波段。该调制器结构紧凑，易于集成，可应用于高速光通信系统。

A Mach-Zehnder modulator based on photonic crystal and nanowire waveguide is proposed. The modulator consists of silicon-based photonic crystal slab waveguides, nanowire waveguides, and two photonic crystal multimode interference couplers (MMI). Designed tapered structures are working at the junction of the photonic crystal and the nanowire waveguide to reduce the loss caused by the mode mismatch. The simulation analysis by time-domain finite difference method (3D-FDTD) shows that the insertion loss and extinction ratio of the modulator with a compact size of only 46 μm × 8 μm × 0.22 μm at the operating wavelength of 1550 nm are 0.3 dB,15.1 dB,respectively. The operation with a wavelength range of 20 nm are obtained at a center wavelength of 1551 nm.The 3dB bandwidth can reach 68 GHz,which allows high speed optical communication systems.