Manipulation of OAM spectrum in four-wave mixing with perfect Laguerre-Gaussian beams

The manipulation of orbital angular momentum (OAM) is a cutting-edge field in modern photonics. However, in four-wave mixing (FWM) processes, the generated OAM mode usually suffers from spectrum broadening. In order to achieve high-fidelity frequency conversion, we investigate the distribution of the OAM spectra generated in the FWM process under different pump beams. Theoretical simulations and experimental results show that using perfect Laguerre-Gaussian pump beams achieves higher mode purity and a narrower OAM spectrum. This scheme has potential applications for constructing frequency interfaces in optical communication and enhancing the resolution of OAM-based nonlinear imaging.