Laser induced spatial self-phase modulation of nano-suspension

The far-field diffraction pattern of laser beam through negatively polarized nano-suspension is studied. Based on the Fresnel-Kirchhoff diffraction integral formula, the relationship between the nanoparticle suspension sample’s placement location, different incident light intensity, different sample length and the far-field diffraction pattern change are compared and analyzed through numerical simulation. The simulation results prove that a perfect hollow beam is obtained by changing the wavefront curvature of the incident light beam. Different from the past, increasing the incident light intensity can not increase the number of far-field diffraction rings. The wavefront curvature is no longer the only factor that affects the far-field intensity distribution of a laser beam passing through a nonlinear medium. With the increase of incident light intensity, the far-field diffraction light intensity distribution tends to be uniform. Increasing transmission distance in nano-suspensions leads to the increase of the number of far-field diffraction rings. The research results of this paper provide a new phenomenon for the study of the nonlinear characteristics of nano-suspensions, which has many critical practical applications and significance in the self-converging waveguide of nano-suspensions, micro-optical field regulator, atom capture, generation of hollow beams, nonlinear control of light field and so on.