利用太赫兹时域光谱技术(THz-TDS)测试向列相液晶E7 和5CB 在磁场、电场和光场作用下的太赫兹光学性质，较为全面地总结向列相液晶在不同场强下的折射率变化。实验观察到E7和5CB 在磁场下的负磁致折变效应和在电场下的正电致折变效应。磁致折射率变化最大达到-0.087，电致折射率变化最大达到0.051，而光致折变与电致折变的物理本质相同，在7.961 W/cm²的532 nm 激光泵浦下折射率变化最大达到0.015。这些研究结果为液晶材料在太赫兹波段的可调相移器、滤波器和空间光调制器等重要功能器件中的应用打下基础。

Abstract Terahertz time domain spectroscopy (THz-TDS) is used to investigate the optical properties of nematic liquid crystals E7 and 5CB under the external magnetic field, electric field and optical field in the THz range. It is systematically summarized that the optical property changes of nematic liquid crystals under different external fields. It is experimentally observed that a negative magneto refractive index change under the magnetic field and a positive refractive index change under the electric field. The maximum values of magneto and electric refractive index changes reach - 0.087 and 0.051, respectively. The physical mechanism of photorefractive effect is the same as electric refractive effect, and the maximum value of photorefractive coefficient is 0.015 under the power of 532 nm laser with 7.961 W/cm² output. These research results are significant for the key THz devices such as tunable phase shifters, filters and the spatial light modulator in THz technology and applications.