中文摘要：

各向异性吸收的菌紫质（BR）分子可以看作一个电偶极子。由大量随机取向的BR分子构成的聚合物薄膜在宏观上呈现光学各向同性。在线偏振光照射下,电偶极矩取向与激发光的偏振方向一致或接近的BR分子被激发到中间态,产生光致异构,而电偶极矩与激发光偏振方向垂直的BR分子大部分仍处于基态。分子结构的改变导致其折射率和吸收系数发生变化,从而使BR薄膜呈现出宏观的光学各向异性。利用抽运探测法测量了BR薄膜的光致双折射特性,并通过BR分子光循环的二态模型对实验结果进行了理论模拟。实验与理论计算结果符合较好。

英文摘要：

The anisotropically absorbing bacteriorhodopsin（BR） molecules can be approximated by linear oscillators.BR film is isotropic in its initial state because of the random distribution of the BR molecules.Upon excitation by a linearly polarized light,those molecules with the dipole moment aligned closed to the polarization direction of the excitation light are dominantly pumped to the intermediate state and produce photoisomerization.However,those with the dipole vector in the perpendicular direction of the pumping beam have a little probability occurring the above change.Due to the change of molecular structure,the refractive index and absorption coefficient of the BR molecules change,then the macroscopic anisotropy was induced as a result.The photoinduced birefringence of the BR film is measured by the orthogonal polarization detection,the experimental results are basically consistent with the simulated results,which are obtained by utilizing the two-state model of BR molecule photocycle.