Diode arrays, phase conjugation, and array mode control

Many applications of diode laser arrays require maximizing the spectral power density ofthe output beam in the far field. For an evanescently coupled array, which usually produces a double-lobe far field pattern, many elaborate experiments have been performed during the last decade to produce the more desirable single-lobe pattern. In the first part of this paper, we propose and demonstrate a new technique for achieving this goal. It is based upon incoherent superposition of far-field lobes, and can be implemented by means of simple external optics. Although simple, the technique achieves single-lobe intensity which is 23% higher than that achievable by any techniques previously developed. In the second part, we report the results of our experimental study of the effects of phase conjugate feedback on the operational characteristics of a gain-guided diode array