Optimization of laser intracavity second-harmonic generation by a linear dispersion element

Changing the relative phase Δφ between the fundamental and harmonic waves produces periodic power modulation of a laser intracavity second-harmonic generated wave. The periodic power modulations of the two counterpropagating second-harmonic waves are at exactly opposite phases. This behavior is different from that in the case of intracavity second-harmonic generation in a passive cavity. A phenomenological numerical model developed for a laser consists of double-pass second-harmonic generation. The steady-state plane-wave model incorporates second-order nonlinear interaction, laser gain, and linear dispersion that contribute to the phase difference Δφ. The model predictions are in good agreement with the experimental results. The model is useful for optimization of laser intracavity second-harmonic generation, and it may be applied to different types of intracavity nonlinear interaction.