Investigation of linear and two-dimensional arrays of semiconductor laser diodes in an external cavity

Linear and two-dimensional arrays of semiconductor laser diodes were investigated in an external cavity with mirrors of various curvatures. The principle characteristics of the output radiation were determined and feedback optimisation of the investigated system with a mirror (focal length F = 1 cm) was carried out. This mirror made lasing possible for 6 diodes in a linear array and for 6 × 5 diodes in a two dimensional array. A mirror with F = 20 cm ensured lasing of 14 × 15 diodes. A study was made of the spatial coherence effects in the external cavity. These effects were accompanied by the appearance of an interference pattern in the far-field zone. An experimental confirmation was obtained of theoretical estimates of the dimensions of a linear array in which phase locking is possible.