Phase locking of short-pulse Q-switched lasers

The effects of frequency mismatch on phase locking of two passively Q-switched lasers have been studied. Stable phase locking with a high degree of spatial coherence can be obtained for frequency mismatches that are less than the spectral linewidth of the laser pulses. As the frequency mismatch increases, the transition from the phase locked to the unlocked states is characterized by a gradual loss of coincidence of the pulses from the individual elements and a reduction in the fringe contrast in the combined laser beam. An explanation for observed phenomena based on the dynamics of the transverse modes of the laser array is provided.