Spin-based second-harmonic generation by metal nanoparticles

The interactions between polarized Laguerre-Gaussian beams and clusters of metallic nanoparticles have been investigated by means of the nonlinear multiple scattering method. The near-field phase singularities and vorticity in the longitudinal component of the second-harmonic field have been discussed. We have found that the phase profile of the second-harmonic field is twice as many helicities as that of the fundamental frequency field. The spin-based second-harmonic generations - spatial splitting of spin states and spin-Hall effect of the second-harmonic field - have been observed. A class of spin-based second-harmonic generation devices is anticipated.