External-cavity designs for phase-coupled laser diode arrays

Both configurations have been extensively studied theoretically as well as experimentally. We have obtained a stable coherent operation of the laser arrays, on a single transverse array mode. The main advantage of the angular filtering cavity is here that it is perfectly adapted to the high filling-factor laser bar, and then provides directly a nearly diffraction-limited output beam; nevertheless these bars have limited output powers because of the strong heating of the array. On the other hand, Talbot external cavities may be used with very different kind of bars, in simple extended-cavity designs. Finally, the use of the filtering properties of VBG has been demonstrated to efficiently control the laser emission.