The transformation of nonplanar periodic laser array modes from weakly locked out‐of‐phase to locked in‐phase operation is investigated. A comparison study of near‐field and far‐field patterns is made for devices with differing mesa widths and heights. Data are presented which show that the mesa height and width can be adjusted to force in‐phase operation. An array of 19 elements shows an essentially single‐lobed far‐field pattern centered at 0° with full width at half maximum of 1.6°, to output powers of more than 500 mW/uncoated facet.