太赫兹波调制器是太赫兹波通信系统中关键的一环，同时，可调谐光子晶体作为一种新兴材料，被广泛地用于制作光通信系统中的调制器、光开关和滤波器等功能器件。光子晶体技术和太赫兹波技术相结合为设计太赫兹波调制器提供了新的思路。提出了一种基于二维硅光子晶体的新型太赫兹波调制器。该光子晶体采用点、线缺陷组合的结构，通过在点缺陷处填充5CB液晶，使其成为可调谐光子晶体。当在点缺陷处外加电场时，此太赫兹光子晶体的缺陷态频率发生动态迁移。基于这种机制，此器件可对太赫兹波的通、断状态进行调制。仿真结果表明，调制器的调制深度大于30 dB，调制速率为10 kHz，具有体积小巧、易于集成的优点。

Terahertz (THz) wave modulator is a key element in future terahertz communication systems. Meanwhile, as a new kind of material, the tunable photonic crystal is widely used to fabricate modulators, switches, filters, and other functional devices in optical communication systems. The combination of THz technology and photonic crystal technology provides a new approach to design the novel THz wave modulator. A novel THz modulator based on the twodimensional silicon photonic crystals is presented. The structure of photonic crystals is consisted of the combination of line defects and point defects, and is designed to be the tunable photonic crystals by filling the point defect with 5CB liquid crystal. By applying the external electrical field on the point defect, the frequency of the defect mode of the THz photonic crystals dynamically shifts. Based on this mechanism, the device can modulate the onoff state of the THz wave propagating. The numerical simulating results show that the THz modulator has a modulation depth of more than 30dB, modulation rate of 10 kHz, and a small size, ease to integrate.