Optical trapping of metallic Rayleigh particles by using coherently and incoherently combined beams
相干和非相干合成光束对金属瑞利粒子的光学俘获

The effect of two beam combination schemes,i.e.combination of coherent and incoherent beam,on the radiation force and stability in trapping metallic Rayleigh particles is studied,where the dependences of the radiation force on beam combination scheme, off-axis distance,coherence parameter and particle radius are stressed and illustrated by numerical examples.It is shown that there exist critical values d_c andα_c for different combination schemes.For 0 < d ^ dc or 0 < a ^ qc the Gaussian-like intensity profile takes place in the geometrical focal plane,so that the transverse gradient force can act as a restoration force to provide stable equilibrium point.For d > do,c orσo >σo,c the transverse gradient force can not trap metallic Rayleigh particles.For 0 < d≤dc the intensity, the radiation force,the trapping stiffness,and the longitudinal trapping range of coherently combined beam are larger than those of incoherently combined beams.Therefore,a suitable choice of combination scheme,smaller off-axis distance and coherence parameter is beneficial to trapping metallic Rayleigh particles in the use of combined beams.