A semiconductor laser structure having the same advantages as a channeled substrate planar laser, but without the difficulties of fabrication associated with this structure. The structure includes a substrate (10), a planar first cladding layer (14), a planar active layer (16), and a second cladding layer (18) in which a mesa region (22) is formed. A blocking layer (24) is formed over the second cladding layer (18) and electrical contact (26) is made through the blocking layer (24) in the region of the mesa (22). The blocking layer (24) functions to confine current flow in the mesa region (22) and to provide index-guiding of light in the mesa region (22). Because of its simple geometry, the structure can be conveniently formed using a desirable fabrication process, such as metalorganic chemical vapor deposition (MOCVD). In one disclosed embodiment of the invention, the mesa (22') is broadened to include at least one intermediate ledge (28) on each side of a central pedestal. This reduces the abruptness of the change in effective index of refraction encountered by the laser light, and reduces astigmatism in the resultant beam.
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