Generating high-fidelity ultraviolet Laguerre–Gaussian mode using four-wave mixing

Abstract

The rapid developments in orbital-angular-momentum-carrying Laguerre–Gaussian (LG) modes in recent years have facilitated progress in optical communication and quantum information. However, it is still challenging to efficiently generate the high-fidelity LG laser modes. We propose a scheme to generate the high-fidelity ultraviolet (UV) LG mode via four-wave mixing (FWM) in a five-level atomic system. It is found that the output FWM field transferred from a probe beam carrying orbital angular momentum (OAM) can be efficiently controlled. Interestingly, by appropriate choices of the system parameters, the FWM field can be significantly enhanced and the maximum FWM conversion efficiency is more than 60%, which is several orders of magnitude larger than many previous investigations. More importantly, the fidelity of the output FWM field is studied and find that the generated LG laser mode has the fidelity approximately 100%. As we known, any light beam can be decomposed as a linear combination of LG beams and we can expand the theoretical approach to the case of an arbitrary LG probe beam. Thus, our work may be exploited for generation of the high-fidelity UV LG mode in a compact, efficient, and robust way.