Interaction Between Laser Light and Helical Structure of Chiral Polar Nematic Liquid Crystal

采用平行于向列型向列型液晶螺旋轴的方法，对聚(γ-L-谷氨酸苄酯)手性向列型液晶进行激光辐照。当光学节距对应于二次谐波(SH)光波长时，在LC中产生二次谐波(SH)光。结果表明，PBLG形成了一种特殊的手性向列相，它由分子偶极矩与分子长轴平行排列的极性向列层组成，应命名为“手性极性向列相LC”。LC中产生的倍频强度和极性依赖于入射光的极性。当线偏振基波光照射到LC上时，产生了线偏振SH光和左圆偏振SH光。另一方面，当左圆基波偏振光照射到液晶时，产生右圆偏振SH光。右圆偏振基光不能诱导SH光。

Nd : YAG laser was irradiated to the chiral nematic liquid crystal (LC) of poly(γ-benzyl-L-glutamate) (PBLG) in parallel to the helical axis of the LC. The second harmonic (SH) light was generated in the LC when the optical pitch corresponded to the SH light wavelength. It leads to the significant conclusion that PBLG forms an unusual chiral nematic mesophase that should be designated as "chiral polar nematic LC", which consists of polar nematic lamellae where the dipole moment of molecule as well as the long axis are parallel aligned. The SHG intensity and polarity generated in the LC depended on the polarity of the incident light. When linearly polarized fundamental light was irradiated to the LC, linearly and left circularly polarized SH light were generated. On the other hand, when left circularly fundamental polarized light was irradiated to the LC, right circularly polarized SH light was generated. Right circularly polarized fundamental light did not induce SH light.