Investigation of optical vortices and hexagonal patterns in the interference of three plane waves

We demonstrated that optical vortices can be created by means of interference of three waves from a common laser source. Different intensity patterns can be generated starting from common two wave interference fringes up to regular hexagonal structures. The created vortices exist throughout the transition from two wave to complete three wave interference and have been shown to move along predictable lines in space under perturbations of contrast of waves. The law of conservation of topological charge was fulfilled for the interference of three waves.