为提高太赫兹（THz）波的产生效率，研究了飞秒激光与铌酸锂晶体的相互作用。分析了块状铌酸锂晶体中抽运光与THz波间的相位匹配，结果显示抽运光的群折射率曲线与THz波的折射率曲线不存在交点，表明了块状晶体结构中相位失配问题的存在。设计了4种不同尺寸的波导结构，根据波导理论计算了波导结构在0.1~6 THz波段的折射率。研究结果表明，铌酸锂波导结构能够有效增大飞秒激光与THz波的相位匹配程度，甚至实现二者间的完全相位匹配，从而提高飞秒激光与晶体耦合过程中THz波的产生效率。另外，还对晶体中THz波的传输距离进行了分析。研究对飞秒激光与非线性晶体耦合过程中的相位匹配增强作用提供了理论依据。

The interaction between femtosecond laser and LiNbO3 crystal is studied in order to improve the terahertz (THz) generation. The phase matching in bulk LiNbO3 crystal between femtosecond laser pulse and the generated THz wave is analyzed, the result shows that phase matching cannot be achieved in this structure, thus the THz generation efficiency in this structure is poor. Four waveguide structures with different sizes are proposed to probe the possibility to overcome this problem. The refractive index curves in the range of 0.1~6 THz are calculated. This result proves the phase matching degree is enhanced in the waveguide structure. Especially, one of the changed refractive index curves is intersectant with the group index curve of femtosecond laser pulse, which illustrates that the phase matching is achieved in this waveguide structure. In addition, the best transmission distance is analyzed in the waveguides. The results serve the phase matching enhancement study during the interaction process of femtosecond laser and nonlinear crystals.