Abstract: Techniques for increasing the spatial and spectral brightness of laser arrays such as laser diode arrays are provided. Passive cavity designs are described that produce wavefront phase locking across the face of large arrays. These designs enable both spatial and spectral selectivity in order to coherently link the individual emitters that make up the diode array. Arrays of customized micro-optics correct aberrations of the individual apertures of the arrays while highly spectrally selective partial reflectors overcome the deleterious effects of inhomogeneities in local thermal environments of the individual emitters that are being phase locked together. Using these two technologies, along with intracavity diffractive beam coupling, solves two long standing problems that have prevented effective and robust phase locking of laser diode arrays.