Manipulation of the orbital angular momentum via four-wave mixing in Rb vapor

Abstract

The manipulation of the orbital angular momentum (OAM) contributes to understand the OAM multiplexing, is significant in free-space optical communication and information processing. We theoretically simulate and experimentally demonstrate the regularity of the OAM transfer, including the angular and radial modes, of Laguerre–Gaussian beam via four-wave mixing process in 85Rb vapor. The 420 nm coherent blue light output field inherits the phase characteristic of 780 nm and 776 nm beams with different OAM modes. The output field OAM modes show the transfer as a typical arithmetic operation of the input field OAM modes with equal-handed angular indice l, while, the conversion between angular and radial modes occurs with the opposite angular indice l. Such rules of the OAM transfer and manipulation have implications on the research of high-capacity information transfer and quantum communication.

Effect of relaxation on the transfer of orbital angular momentum via four-wave mixing process in the four-level double lambda atomic system

“…The non-degenerate FWM process is used for mode transfer in the case of non-diffracting beams [43]. Transfer of OAM is studied experimentally in Rb vapor by several authors [44][45][46][47]. Atom-based optical vortex transfer has attracted attention in recent years because it is based on all-optical methods, and the presence of coherently prepared media can lead to sizeable nonlinear conversions [48].…”