Efficient frequency conversion by amplitude modulation

An efficient wavelength conversion scheme based on amplitude modulation is proposed, and it demonstrated by mathematical formulate in an MgO-doped LiNbO3 quasi-phase-matched waveguide. This method is based on the adiabatic physical process of two-state systems. By nonlinear modulate the overlap of waveguide modes to achieve the purposes of phase-matching and modulate the coupling coefficient. Under the adiabatic constraints condition, we simulate numerically difference frequency generation process. The results shown that this scheme can lead to almost complete transfer of energy from near-IR (~1064 nm) to mid-IR (~3.53 µm) in a stable manner. Furthermore, we also present two analytically exactly soluble models, in which the coupling coefficient is a linear function of propagation distance and the phase mismatch is a constant.