摘要 : We report the observation of the nucleation oi pairs of screw dislocations of opposite topological charges in second-harmonic generation processes in quadratic nonlinear media. The observation provides evidence about the conservat... 展开 We report the observation of the nucleation oi pairs of screw dislocations of opposite topological charges in second-harmonic generation processes in quadratic nonlinear media. The observation provides evidence about the conservation and evolution of the topological charge of light waves parametrically interacting in the nonlinear medium in the dynamical regime explored. [S1063-651X(98)12111-6]. [References: 23] 收起