Hidden chains of optical vortices generated using a corner of phase wedge

In the framework of paraxial approximation we consider evolution of a monochromatic Gaussian beam diffracted by a corner formed by three verges of the phase wedges of different types and the pi -phase plate. We have found that the edges of the phase wedge generate macroscopic chains of identical optical vortices that disappear at the far field zone. At the same time, the pi -phase plate can reproduce a very complex wave field whose structure depends on the scale of observation. At large scales there appear two pi -cuts resembling broken edge dislocations with perpendicular directions. At small (some microns) scales two short vortex chains consisting of alternating-sign optical vortices are nucleated near the corner of the wedge. The analysis shows that the sizes of the chains decrease quickly when approaching the wedge surface. This enables us to assume that the pi -phase plate can create so-called optical quarks in the evanescent waves of the edge field.