Second harmonic generation in a YAG laser with selflocking of longitudinal modes

A theory is developed of intracavity second harmonic generation in multimode continuously pumped lasers with a homogeneously broadened gain profile. An analysis is made of the amplitude distribution and phase relationships between the generated modes. A theoretical and experimental study is reported of the spontaneous establishment of frequency modulation of the output radiation of a YAG laser with self-locking of longitudinal oscillation modes and intracavity frequency doubling. The conditions for the occurrence of this effect are determined. Spectral and time characteristics are given for the fundamental frequency radiation and for the second harmonic emitted by the YAG laser.