Elementary treatment of second-harmonic generation. The treatment of second-harmonic generation presented in the text is in many ways too mathematically complicated to allow for a simple conceptual understanding of the process. As an alternative, simpler approach, carry through the suggestion presented the sentence that follows Eq. (2.7.12). In particular, solve Eq. (2.7.11) in the un deplated pump limit and then use this result to express the intensity of the generated field in terms of the intensity of the fundamental field, the length L of the interaction region, and the value k of the wave vector mismatch.