瑞利粒子在贝塞尔光束中的横向受力

Transverse trapping force on a Rayleigh particle in Bessel beam

为寻找捕获瑞利粒子的最佳光场,利用电磁模型推导了贝塞尔光束捕获粒子的最小半径的表达式,并数值计算了瑞利粒子在贝塞尔光束和高斯光束中所受的横向力和势阱的深度。结果表明:当激光功率为4 W时,贝塞尔光束仅能在光轴处稳定地捕获瑞利粒子;当激光功率达到6 W时,贝塞尔光束能够在光轴和次极大位置捕获瑞利粒子。在相同的激光参数条件下,高斯光束无法克服布朗运动的影响稳定地捕获瑞利粒子,贝塞尔光束更有利于捕获瑞利粒子。

In order to obtain the most suitable optical fields to trap the Rayleigh particles, the expression of the minimum particle radius for Bessel beams capture was deduct through the electromagnetism model, and transverse forces and potential depths were calculated for Rayleigh particles in Bessel and Gaussian beams respectively. The results indicate that Rayleigh particles can be stably trapped under an incident power of 4 W only at the maximum of the optical fields, and the positions of trapping particles in the optical fields are the maximum and the secondary maximum for an incident power of 6 W. With similar laser parameters, Gaussian beams can not overtake the influences of Brownian motion to capture the Rayleigh-particles as Bessel beams do. Therefore, Bessel beams are better to trap the Rayleigh particles.