双折射晶体微粒光致旋转受其半径影响分析

Analysis of radius effect on optical rotation of birefringent crystal particles

利用双折射晶体微粒在具有自旋角动量的光束作用下可产生围绕自身光轴旋转的特性,在光镊实验平台上实现了双折射晶体微粒的光致旋转。为了提高晶体微粒的旋转频率,从理论和实验上对双折射晶体微粒的旋转频率受其半径的影响进行了分析。用MATLAB模拟出CaCO3晶体微粒和SiO2晶体微粒的旋转频率与其半径的三次方成反比的关系曲线,并测得相应的实验关系曲线,其结果与理论分析相吻合。在相同的激光功率下,CaCO3晶体微粒的最高旋转频率可达15.1 Hz,SiO2晶体微粒的最高旋转频率可达11.4 Hz。该结论可用于光致旋转在实际应用中晶体微粒大小的选择和其旋转频率的优化控制。

The principle of optical rotation due to the transfer of spin angular momentum from light to particles was discussed by analyzing the interaction between beam of light and birefringent crystal particles.The optical rotation of birefringent crystal particles was realized by using the equipment of the optical tweezers in experiment.For increasing the rotation frequency of crystal particles,the relation between rotation frequency of crystal particles and radius was analyzed in the experiment and theory research.The relation curve between calcium carbonate and silicon dioxide particles′ rotation frequency and radius was simulated with MATLAB,and the result showed that the rotation frequency was inversely proportional to the cube of radius,in addition,the experimental data was in agreement with the theoretical simulation.Rotation frequency was measured in experiment with the same laser power,the result showed the maximum frequency of calcium carbonate was 15.1 Hz,and the maximum frequency of silicon dioxide particles was 11.4 Hz.The rationality of the experiment was testified compared with theoretical analysis.The conclusion can be used to the choice of crystal particles and the optimization control of rotation frequency in actual application.