光梯度力在光镊技术中起着非常重要的作用。数值模拟了螺旋相位调制双曲余弦高斯光束在焦平面上光梯度力的变化。研究结果表明:双曲余弦高斯光束的偏心参数、螺旋相位的拓扑数可以显著地调节光梯度力分布,并且会出现一些新奇的光梯度力分布,如构成圆环形光陷阱、矩形光陷阱、阵列光陷阱等;另外,对于不同数值孔径、不同拓扑数,光梯度力随双曲余弦高斯光束的偏心参数的演化规律也显著不同。

Optical gradient force plays a very important role in the optical tweezers.The focusing properties of the cosh-Gaussian beam induced by spiral phase plates are investigated numerically.The phase plate may alter the wavefront phase of the cosh-Gaussian beam by topological charge which results in spiral optical vortex.Results show that the topological charge of the spiral phase plate affects focal intensity distribution significantly.Some novel focal patterns appear in focal evolution with different topological charge.And the gradient force distribution can be altered significantly by decentered parameters of cosh-Gaussian beam and topological number of the spiral vortex.Many novel gradient force patterns occur,which means corresponding optical trap including ring optical trap might become rectangle trap pattern,array optical trap,and so on.In addition,as for different numerical aperture and different topological numbers,the evolution law of the optical gradient force is also different from the centrifugal parameter of the cosh-Gaussian beam.