We report experimental results on the dynamics and synchronization of a 19‐broad‐area semiconductor laser array in an external cavity containing a lens array, projection optics, and a diffractive grating. All lasers are locked to single longitudinal mode. Significant improvement of the spatial profile of the entire laser array output beam has been observed. Laser coupling is investigated through the radio‐frequency (RF) spectrum and temporal correlation of coupled laser emitters. Such coupling is found to exert certain effects on the frequency locking of the laser array. © 2004 American Institute of Physics