Single-mode operation of a broad-area semiconductor laser with an anamorphic external cavity: experimental and numerical results

The emission of high-power broad-area semiconductor lasers inherently conta ins many lateral modes that increase the beam divergence and reduce the spa tial coherence. Elimination of higher-order lateral modes from the output b eams of commercially available broad-area lasers will be beneficial in many applications of these lasers. Experimental results obtained with a broad-a rea laser coupled to an anamorphic external cavity are presented and are co mpared with the predictions from our numerical model. We have predicted and observed with the anamorphic external cavity a greatly improved discrimina tion against high-order lateral modes. The measurement of the spectrally re solved near-field intensity patterns provides much more comprehensive infor mation on their longitudinal- and lateral-mode content than do observations of mar-held and far-field beam intensity profiles. With a broad-area laser of 100-mW nominal power, it has been possible to extract 40% of the maxima l power in a stable single-lateral and single-longitudinal mode regime. (C) 2000 Optical Society of America OCIS codes: 140.5960, 140.3570, 140.3410.