在传统的基于全内反射原理的低折射率比介质波导所构建的相位移调制型光学器件中，调制区域的长度通常在毫米到厘米量级.由于器件横向尺寸保持在微米量级，因此狭长结构成为了传统光波导器件的典型特征，这限制了光学器件集成度的提高，严重制约了集成光路的进一步发展.光子晶体的出现为高密集成光路的发展提供了一条新的途径.本文使用平面波展开方法计算了光子晶体线缺陷波导中的色散曲线.研究发现: 在色散曲线下边缘处，材料折射率的一个微小变化可以引起传输常数的较大变化，如果工作频率点选择在带下边缘附近，则可以大幅度减小相位移调制型器件调制区域的长度.本文使用时域有限差分方法进一步验证这种增强效应，计算结果表明，对于0.46%的折射率变化，光子晶体线缺陷波导中的相位调制长度仅为均匀媒质中相位移调制长度的11.7%.通过以进一步研究，这种增强效应有望应用与高密度集成光路.

In the phase shift modulation type optical components constructed by traditional dielectric waveguides with the low refractive index constant based on the total inner reflection mechanism, the length of the modulation region is usually millimeter or centimeter order of magnitude, while their horizontal size is micrometer of order of magnitude, therefore, the most typical characteristics of optical waveguide devices are long and narrow. Reducing the size of optical waveguide devices is a hard problem in the development of highly dense integrated optical circuits. The emergence of photonic crystals provides a new approach to develop highly dense integrated optical circuits. The plane wave expansion method is used to calculate the dispersion curves of the line-defect type photonic crystal waveguides. It is observed that there is a large change of wave prorogation constant near the guided-wave band edge, corresponding to a little change of refractive index of the material. If the work frequency is selected near the guided-wave band edge, the phase shift modulation length is expected to largely reduce. The finite-difference time-domain method is used to demonstrate the results above. Calculated results indicate that there is strong enhancement effect of refractive index phase shift modulation near guided-wave band edge: for the refractive index change of 0.46%, the phase shift modulation length in these waveguides is only 11.7% of that in conventional uniform dielectric material. This enhancement effect is originated from the special flat dispersion properties near the guide-wave band edge, and it is expected to be applied to high dense photonic integrated circuits after further research.