High-Performance Red Lasers With Low Beam Divergence

We report the design and fabrication of high-performance 650-nm lasers using a novel wafer structure that offers substantially independent control of the vertical far field and of the optical confinement factor. By incorporating a graded V-shaped layer into the epitaxial structure, a low divergence can be realized while retaining high optical overlap with the quantum wells and, therefore, a low threshold current. Broad-area lasers (BALs) were fabricated for a range of designs, and close agreement was obtained between the modeling and the experiment.