Abstract

High-spectral-purity pulse and cw coherent output have been obtained from a linear array of five discrete external-cavity diode lasers by placing in the cavity a spatial filter at the Fourier plane of the lens system between the AR-coated diodes and the feedback mirror.^1,2 Results are reported on the intensity and phase distribution of the near field of the ensemble. Two modes of operation are shown to exist: in one, the outputs from adjacent diodes are in phase; in the other they are 180° out of phase. These modes of operation are switched by moving the filter laterally by half of the spacing between the centers of its slits. Limited tuning of the output wavelength has been accomplished by tilting the filter and thereby, in effect, varying this center-to-center spacing. The experimental results are compared with those predicted by theory and clearly validate the model of ensemble operation used to explain previous results.

© 1987 Optical Society of America