Intracavity second harmonic generation in actively mode-locked lasers

An investigation is made of intracavity second harmonic generation in activity mode-locked lasers. It is shown theoretically and experimentally that the process of frequency conversion inside a laser resonator strongly influences the duration and shape of the fundamental-frequency radiation pulses. An improvement in the radiation conversion in an intracavity system compared with an eztracavity one is only obtained if the nonlinearity parameters of a frequency doubler are small or its length is short.