Analysis of radius effect on optical rotation of birefringent crystal particles

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.