Observation of a triangular-lattice pattern in nonlinear wave mixing with optical vortices

Preparation, control, and measurement of optical vortices are increasingly important, as they play essential roles in both fundamental science technology applications. Spatial light modulation is the main approach behind control strategies, although there limitations concerning controllable wavelength. It therefore crucial to develop approaches that expand spectral range modulation. Here, we demonstrate by nonlinear interactions identification topological charge vortices. A triangular-lattice pattern observed beams resulting from spatial cross between an vortex a triangular shaped beam undergoing parametric interaction. Both up- downconversion processes investigated, far-field image converted exhibits lattice. The number sites lattice orientation determined beam. In process, can also be affected phase conjugation. works for large variety field structures. Our results show used at wavelengths which solid-state devices not yet available.