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提出用纳米光学透镜替代传统光镊装置中的大数值孔径几何光学透镜来捕获瑞利粒子的设想,基于电磁场时域有限差分方法计算了平面波经过纳米透镜后的衍射光场,并结合点偶极子近似计算了瑞利粒子在透镜衍射光场中的受力。研究结果表明,与传统光镊最好的情况(焦斑接近衍射极限)相比,本方案的捕获效率、稳定捕获区长度和光镊的品质因子都有很大程度的改善,尤其是出现在纳米透镜两侧的捕获区,对瑞利粒子的捕获效率和品质因子可提高2～3个量级,而且捕获粒子的受力具有强偏振相关性(不同于传统光镊),可用来实现粒子的旋转操作。
The idea of replacing the Rayleigh particles with a large numerical aperture geometrical optical lens in a conventional optical tweezers device is proposed. A diffractive optical field after the plane wave passes through the nanoscopic lens is calculated based on the finite difference time domain method of the electromagnetic field. The approximation of Rayleigh particles in the lens diffraction field is given. The results show that the capture efficiency, the length of the stable capture zone and the quality factor of the optical tweezers are greatly improved compared with the best case of the traditional optical tweezers (focal spot close to the diffraction limit), especially in the nano Capture zones on both sides of the lens increase the capture efficiency and quality factor of Rayleigh particles by two to three orders of magnitude, and the forces on the captured particles have strong polarization dependence (unlike conventional optical tweezers) that can be used to achieve particle Rotate operation.