Cascaded wavelength conversions based on sum-frequency generation and difference-frequency generation

A novel wavelength conversion scheme based on cascaded sum-frequency generation (SFG) and difference-frequency generation (DFG) is proposed and demonstrated in a MgO-doped LiNbO3 quasi-phase-matched waveguide. In this scheme, two pump wavelengths are set outside the communication band. It is shown that the same conversion efficiency can be achieved by use of two pump sources with lower output power (P1, P2) in this scheme compared with the conventional cascaded wavelength conversion technique based on second-harmonic generation and DFG with a single higher-power pump beam (P = P1 + P2) that is due to the use of a larger SFG nonlinear coefficient. The results significantly influence the selection of a suitable nonlinear interaction scheme for practical applications.