A Theoretical Description of Integrated OAM Beam Emitters Using Conical Wave Model

A theoretical model, suitable for multiple structures of integrated vortex beam emitters, is proposed, developed and verified. Using the interference superposition of multiple plane waves in the far-field plane, which have the same wavevector in the z-direction, the expressions of the orbital angular momentum (OAM) beam field emitted from integrated devices are obtained. The results are applicable to OAM beams with larger or fractional topological charges, and consider different initial polarization states, which means different structures. Especially, when ϑ = 0, p = 0, the result is the same as those derived from the dipole model and is consistent with the previous experimental results. The calculated results show that it can obtain more accurate far-field light field with topological charge l increasing gradually and gain the same Ex and Ey with different initial polarization states. By constructing this model, the generation mechanism of the integrated OAM beam emitters can be easily understood and the beam vortex can be generated naturally and flexibly.