Study of fundamental wave depletion in intracavity second harmonic generation.

In this paper, a novel approach to modelling intracavity second harmonic generation (SHG) in periodically poled MgO-doped lithium niobate (PPLN) is presented and verified against experimental results. This approach involves combining the coupled nonlinear wave equations with a rate equation model for a diode-pumped solid-state Nd:YVO₄ laser, taking into account both the depletion of the fundamental wave due to the energy conversion from the fundamental wave to the SHG wave and the reduction of the fundamental wave within a laser cavity due to the loss as a result of the SHG nonlinear process. It was shown that the theoretical simulation matched the experimental results well, while also providing physical insight into the importance of the fundamental wave depletion in the intracavity SHG nonlinear processes. The resulting model is computationally simple and has the potential to generalize to the other nonlinear processes such as three-wave mixing and optical parametric oscillation.