Optical vortex transfer via four-wave mixing in an electromagnetically induced transparency system

A single photon in an optical vortex can encode more than one bit of information, which holds great promise for significantly enhancing the capacity of optical communications and data storage. Additionally, research based on electromagnetically induced transparency (EIT) and four-wave mixing (FWM) provides powerful tools for applying vortex light. Therefore, various application requirements can be met by utilizing the FWM process within the EIT system to adjust properties related to the orbital angular momentum (OAM). Here, we propose a theoretical scheme to achieve vortex FWM in a five-level atomic system. This model can significantly enhance FWM in optically thick media. In such media, an EIT window can be opened in the system through an externally applied strong coherent field to suppress the absorption of the weak probe field and achieve efficient FWM. Meanwhile, we introduced vortex light carrying the OAM in the nonlinear FWM process. Our research demonstrated that the helical phase of the vortex beam is effectively transferred to the generated FWM field, and the vortex FWM field can be manipulated by adjusting the relevant parameters. We also explain the corresponding changes based on the dispersion relation, which closely aligns with simulation results.