An antiguide laser diode array has been fabricated which radiates a predominantly single lobe far field with a full-width at half-maximum of 1.5 times the diffraction limit at a continuous wave output power of 500 mW with a differential quantum efficiency of 50%. By spectrally resolving the far field of the device at high operating powers it is shown that the two longitudinal modes correspond to adjacent lateral modes of the array. The operation of the second lateral mode is the result of spatial hole-burning of the first optical mode.